Post by organizinlady on Aug 14, 2010 21:21:25 GMT -5
ENTERIC DISEASES OF CATTLE
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ENTERIC DISEASES OF CATTLE
Lecturer: Dr. Donal O'Toole
Enteric diseases are those that affect the intestinal tract. Enteritis means inflammation of the intestines, specifically, the small intestine. Colitis is inflammation of the major portion of the large intestine (colon). The suffix –itis means inflammation, so typhlitis means inflammation of the cecum, rumenitis inflammation of the rumen, and so on. Enterocolitis is the term for inflammation of the small intestine and colon. Such inflammation leads to diarrhea (“scours”). Different infectious agents affect specific parts of the digestive tract. For example, rotavirus tends to affect the small intestine, coronavirus both large and small intestine, and pathogenic coccidia the large intestine primarily (in ruminant species).
Neonatal diarrhea (“calf scours”)
A “neonate” is a newborn infant. "Neonatal” generally refers to animals up to 1 month of age. Calf scours are among of the most common and costly diseases of cattle. It is the number 1 killer of dairy calves and the number 2 killer of beef calves (after respiratory infections, and when dystocia death loss is excluded).
Enteric disease, which includes diarrhea, is a major killer of diary calves, accounting for more than 40% of death loss in medium size (100 - 499 cow) operation.
Enteric disease accounts for 13% of death loss in beef cattle, ranking second to respiratory disease (primarily pneumonia) as a major cause of death.
About 10% of all dairy calves and 5% of all beef calves die of scours from all causes. Most cases are due to infectious agents, often occurring in combination. Indigestion, fever, heart failure and other non-infectious disease processes can also result in diarrhea as a clinical sign. Calves that have diarrhea have deficits in water and electrolytes. If diarrhea continues unchecked, calves become glucose deficient (hypoglycemic) and their blood becomes excessively acid (acidosis, due to loss of bicarbonate). These must be reversed if the animal is to survive.
Age: Most fatal cases of calf scours occur within the first 2 - 3 weeks after birth. Although outbreaks occur after 2 - 3 weeks of age, such calves are larger and better equipped to deal with the dehydration and survival rates go up dramatically. After ~3 months of age, diarrhea outbreaks are uncommon except for coccidiosis, a protozoan infection that is common as a clinical disease in weaned calves in late fall and winter months.
Infectious agents: Numerous viral, bacterial and protozoal agents that can cause scours in neonatal calves, lambs and foals. We will deal with calves, but realize that similar disease agents occur in lambs and foals. Those agents are:
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Viral: rotaviruses and coronaviruses
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Bacterial: E. coli, especially with K99 pili, Campylobacter jejuni, Salmonella spp., Clostridium perfringens, especially type C and D
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Protozoal: Eimeria spp. coccidia ("coccidiosis"; usually older calves; generally not a neonatal disease) and cryptosporidia.
In northern plains states, rotavirus, coronavirus, K99 E. coli, and cryptosporidia are the main agents that cause large scour outbreaks. The first 3 are more commonly associated with high death rates. Some of these pathogens are zoonotic (Salmonella spp., Cryptosporidium spp., and some enteropathogenic E. coli strains). Take care to protect yourself when handling calves with diarrhea or contaminated bedding.
Clinical signs:
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Diarrhea. The color of the stool is of little diagnostic importance. The presence of blood and mucus may help determine the site of inflammation. Blood that is bright red suggests hemorrhage is in the lower bowel (primarily large intestine). Dark red to black blood (= partly digested) indicates bleeding higher up the digestive tract, since it has opportunity to be degraded in the digestive process. The cause of diarrhea ranges from damage to the intestinal lining (mucosa), which prevents water absorption and fluid leakage into the lumen of the gut, to toxins (e.g. the exotoxin of K99 E. coli) that stimulate water excretion into the gut.
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Dehydration. As the animal loses fluids, they become dehydrated. The circulatory system begins to fail from lack of volume. This leads to:
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Shock (inadequate perfusion volume in the circulation) and hypothermia, and finally:
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Death, and the welcoming arms of God.
Calf Severity % Dehydration Features What to do
Mild <5% body weight - Calf can stand
- Skin tents for <4 sec
- Calf sucks from bottle - Leave cow on cow
- Alternate milk electrolyte feedings via bottle or stomach tube; at least 2 milk feedings + 2 electrolyte feedings daily for 80-100 lb calf
Moderate 5-7% body weight - Calf lying down (sternal)
- Skin tents for 5 sec
- Limbs cold
- Mouth warm & sticky
- Eyes slightly sunken - Move calf to warm area
- Stomach tube and feed 1/2 gallon warm high energy electrolyte solution (e.g. Entrolyte) every 2-4 hours
Marked >9% body weight - Calf lying down (lateral)
- Semi-comatose
- Eyes markedly sunken
- Mouth dry & cold - Veterinary care
(needs I/V fluids to survive)
With most of these agents, a low-grade fever may be present early on. As the calves dehydrate, they can no longer maintain core body temperatures and they become hypothermic (below normal). The degree of dehydration can be estimated by the skin tent test (above)
Transmission: Spread is by the fecal-oral route, i.e. from infected fecal material being ingested, usually during nursing from contaminated udders and teats. Adults in the herd are the initial source of most agents, with some exceptions. As more calves become infected, the level of contamination and rate of spread increases. Scours are usually seen in the latter half of the calving season due to a buildup of organisms in manure, barns, sheds, corrals and bedding.
Factors that increase the odds of calf scours:
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Management. Crowding, housing and poor sanitation (esp. wet or damp bedding and lying on manure).
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Failure of passive transfer (FPT) of colostrum. This is especially true of first calf heifers due to poor mothering instincts plus they give less milk. These animals may have not been exposed to the agents sufficiently and have less antibody to that agent. Poor nutrition = less colostrum. Cold stress decreases absorption of antibodies. Dystocia reduces the calf's interest in feeding, and delays nursing. If you decide to use commercial sources of colostrum, be aware that they differ markedly in quality. For example, a comparison between feeding with natural colostrum and two commercial sources (Land O'Lakes colostrum replacement, Land O'Lakes Inc; Immu-Start 50 - Imu-Tek Animal Inc.) found the following:
Group Serum IgG (mg/dL) Percent calves with adequate immunity
Colostrum 2,720 ± 1,020 90%
Land O'Lakes 1,160 ± 290 81%1
Immu-Start 700 ± 220 10%
1: Note: 95% of calves fed two rather than one package of this product had adequate immunity
Source: Foster et al: 2006, JAMVA 229 (8): 1282 - 1285
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Weather. Stress from severe cold, overcrowding or wet conditions may increase cortisol levels and lead to suppression of the immune system.
Human error is a big factor in many outbreaks, due to concentration of livestock creating many of the above factors.
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Common causes of diarrhea in calves
Coronavirus: Common and deadly, resulting in losses of up to 10%. It causes severe loss of cells covering villi of the small intestine and the surface of the large intestine, resulting in inability to absorb fluids and nutrients. It is generally seen in calves 1-2 weeks. It occurs as early as 3 days and as late as 1 month.
Rotavirus. It is a common cause of scours. Rotaviruses cause diarrhea in man, foals and other animals, but each is species-specific so the calf agent doesn’t infect people. Generally, rotaviral diarrhea is milder than coronavirus infection. It is not highly fatal unless mixed infections with more than one agent occur. It is destroys cells in the small intestine only, and then only at the tips of villi. It can occur up to about 3 months of age. It is a big problem in first week of life. Such calves are small and vulnerable to the complications of diarrhea. Rotaviral diarrhea tends to occur for a shorter period and earlier in a calf’s life than coronavirus, but they do overlap temporally, often in one outbreak. This is a hardy virus that survives well in the environment.
Bovine viral diarrhea virus. On its own, in healthy calves, it causes transient illness with fever and mild diarrhea. It is a more serious problem when calves are born persistently infected. BVDV is covered in a separate lecture.
Escherichia coli. This genus-species contains hundreds of different strains of bacteria. Most are not pathogenic. Many are beneficial, like those that colonize the intestinal tract. The pathogenic ones come in three forms:
- K99+ and other enterotoxigenic E coli strains. It is specific for calves and lambs. The K99 antigen is a pilus on the bacterium which allows the organism to attach and colonize the mucosa of the small intestine, so that we see dense mats of bacteria adhering to the surface microscopically. The K99 strains have plasmids that code for a potent exotoxin (enterotoxin) that increases water secretion into the lumen of the gut, resulting in diarrhea. Incidence varies from year to year, but is can be controlled with vaccination. This is seen in calves <1 week old. This is the most common cause of “white scours.”
Attaching and effacing E. coli. (= AEEC). These are rare but becoming more of a problem. Most cases in calves older than 1 week.
Septicemic strains. Some strains of E. coli can penetrate the gut and spread via the blood to other organs where they cause pneumonia, joint infections, and encephalitis. The term colisepticemia is applied to these strains. They also may cause navel infections when they enter via the navel at the time of birth. Depending on the strain involved, calves can die quickly (~6 hours) of onset – often they are just found dead. These animals are difficult to save and require intensive veterinary treatment (I/V fluids; glucose; systemic antibiotics; bovine immunoglobulin).
Cryptosporidia. See parasitology notes. “Crypto” is a coccidian protozoal agent, although when we refer to coccidiosis in calves we are talking about the Eimeria genus of protozoa, and not crypto. It causes mild enteritis and is rarely fatal by itself. Mixed infections with other agents are common. Because of its life cycle, it is not seen in calves <5 days of old. It is zoonotic.
Coccidiosis. See parasitology notes. A protozoan agent that affects older calves, especially weaner calves in late fall and winter. Rarely a problem in the first month of age, although we have seen it cause fatal blood diarrhea and/or straining (tenesmus) in calves as young as 2 weeks.
Salmonellosis. This ubiquitous disease affects practically all species of vertebrates. It is mostly a problem in dairy operations, but we see it every year in Wyoming beef herds. It affects all ages. Clinical signs are most common in young, old, and debilitated animals, and in people. The CDC reports approximately 40,000 confirmed cases of salmonellosis annually; the estimated number of human cases of gastroenteritis due to salmonellosis in the US annually is 1.4 million, with ~300 deaths. The most commonly identified agent causing human salmonellosis is linked to poultry, poultry products, and eggs (Salmonella enterica serovar Enteritidis). Salmonella serovar Typhimurium, which infects cattle, is the second most common isolate from human cases. One strain of this organism is called Salmonella ser Typhimurium PT DT104. DT 104 has become an important food safety concern because of the increased incidence in both human and animal infections in the United States, as well as its resistance to multiple antimicrobials, including chloramphenicol, its veterinary analog florfenicol, as well as streptomycin, the sulfonamides, and ampicillin. When we get an isolate we send it to the public health laboratory in Cheyenne for typing so it can be compared to salmonellosis isolates from people – we’d had several hits where isolates match up. The most common sources of infection are contaminated food and water. Approximately 40% of all animal-origin feed additives (bone and fish meal) are contaminated with Salmonella spp. A survey of cattle feeding states in the United States for Salmonella spp in cattle feed lots revealed that 6.3% of 10,417 fecal samples were positive - another good reason, if you need one, why children (and adults) should treat fecal material with respect. Human sewage has also been tracked down as a source of infection in some herd outbreaks. Rodents, birds, and other animals spread infection through their feces and their carcasses.
There are two clinical forms of the disease in ruminants:
Enteric: Adults primarily show the enteric form. It is a big deal in horses, particularly when crowded and stressed. It is addressed in this course under enteric diseases of horses. In cattle it tends to remain an enteric disease and not get into the bloodstream. It is most often seen in cows at term. Horses by contrast can become septicemic. Cattle and horses can both be persistent, chronic carriers either with or without clinical signs of ill thrift.
Septicemic: Calves, lambs, and goat kids are especially vulnerable to septicemia. Failure of passive transfer, crowding, chilling, transport, and poor nutrition make young animals more susceptible to the disease. It generally occurs in calves 1 – 12 weeks old. Often they start with enteric signs (often with blood and mucus in stool), progressing to systemic disease with pneumonia, multiple joint infections (polyarthritis) and encephalitis-meningitis. Morbidity and mortality rates are high.
Veterinary treatment is required to save animals. In beef calves the simplest and safest practice may be to euthanize calves with clinical salmonellosis since it is difficult to know when a recovering animal has cleared the infection. The carrier state in cattle persists for as long as 10 weeks. Please DON’T knowingly sell calves that have had salmonellosis.
Clostridium perfringens type C and D. This rarely causes scour outbreaks. In most situations it is a problem that affects a small number of individuals (<5% death loss). We have seen situations where a herd of pregnant cows that have never been vaccinated for C and D are moved onto a new property, and a wreck with ~25% mortality in young calves ensures. More typically, losses occur in older (1 – 3 month old) calves, often the best in the bunch. Once calves show clinical signs, it is generally late to save them. The clinical course is rapid and calves are found dead. Less commonly, bloody scours are seen and calves exhibit abdominal pain (colic) and convulsions; you may see feces with what looks like pieces of wet paper in it. This is fibrin passed from necrotic guts. It may occur in vaccinated herds. The toxin produced by the organism causes severe necrosis and hemorrhage of the surface of the small intestine and proximal part of the large intestine, hence the common term for the disease, purplegut. You may hear the term enterotoxemia, but this should be reserved for type D Clostridium perfringens enteritis. The organism is a normal inhabitant of the calf’s small intestine. Factors triggering proliferation are poorly understood. Some properties in Wyoming have recurring problems with the disease, so we assume it is cycles between soil and gut/teats. Heavy feeds of milk or colostrum appear to precipitate disease. C. perfringens proliferates in the presence of starches and sugars in the small intestine. In mature cattle these are predominantly digested in the rumen, and not available to the C. perfringens. In pre-ruminant calves, nearly all feed bypasses the rumen and is digested in the abomasum (true stomach) and the small intestine, so starches are available. This, coupled with a normal intestinal flora that has not yet developed, provides a suitable environment for the C. perfringens to proliferate. Several factors contribute to this rapid proliferation. Primary among these are abrupt changes in feeding patterns, physical or environmental stress, nutritional deficiencies, and conditions that impair movement of the intestine (such as diarrhea due to other causes).
Purple gut in a calf. The intestines that are dark purple on right are necrotic (dead tissue). The pink tissues on left are more normal. Calves with this amount of damage in their intestines typically exhibit colic. Damage of this severity cannot be corrected even with prompt antibiotic treatment.
Control is obtained by vaccinating dams with C and D toxoid on two occasions, the last given ~2 weeks before parturition; vaccinate the dams annually thereafter. If you haven't done this, and start losing calves that are confirmed to be due to Clostridium perfringens C or D, your options are to give antibodies ("antitoxin") either orally or subcutaneously at birth, or to vaccinate the calves at birth. Calves should be re-vaccinated at 2 - 4 months.
Review of enteric clostridial diseases in cattle, from South Dakota State University
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Diagnosis of agents of scours: This requires laboratory assistance. Knowing the cause helps determine the best course of action, including what type of vaccine to use the following year. If you use a product and have seen a disease break, talk to your veterinarian about going to a different product.
Treatment: If a calf is scouring, regardless of the cause, rehydration is the most important treatment (see above):
Oral fluids/electrolytes: There are many oral fluid/electrolyte products on the market. They are mixed with warm water and given via esophogeal ("stomach") tube. Oral electrolyte solutions are formulated to replace lost water, replace electrolytes (potassium, sodium, chloride, bicarbonate), alkalinize the recipient, and provide nutritional support by giving dextrose. Bicarbonate is the best alkalinizing agent. An energy source (glucose, dextrose, glycine) is added to facilitate small intestinal uptake of electrolytes and to correct the hypoglycemia. The energy level in commercial formulations is insufficient to meet calves’ caloric demands and they can starve to death if food is withheld for over 48 hours. Commercial products vary in cost and quality. If an 80 lb calf is 5% dehydrated, it needs those ~4 lb back as fluid (1 lb approximately = 1 pint) so the deficit is 4 pints (~ 1 liter). This should be split about equally between milk and electrolytes. It is difficult to over-hydrate a calf, but be careful not to give it inhalation pneumonia by feeding too fast – split the feedings. OK, so a 100 lb calf that is 5% dehydrated needs how much fluid replacement?
Antimicrobials: Most cases will be viral or protozoal, agents that are not affected by them. So, these are not recommended unless you know you are dealing with specific bacteria, or suspect septicemia (very rapidly progressive collapse of the calf). Don’t kill remaining good bacteria in the gut unnecessarily.
Probiotics: These are microbial replacements to aid the gut. In nursing animals, those with Lactobacillus spp. may be helpful in reestablishment of normal gut bacteria. Can’t hurt, but may not help.
Warmth: Hypothermia is an important complicating factor in Wyoming. Warm water baths are best. Warming rooms, hair dryers and heating lamps also work if calves are not too cold.
Prevention:
1. Good management
Adequate nutrition of the dam
Good hygiene and sanitation
Reduce crowding
Decrease weather stress if possible
May want to change calving season if possible
2. Adequate colostrum.
This is tied to the cows’ nutrition and genetics. Don’t interfere too early with the bonding between the cow and her calf. The biggest problem will be with first-calf heifers. If the cow dies for some reason or will not allow the calf to nurse, giving natural or commercial colostrum will be required within the first few hours.
3. Vaccinate dams to increase specific antibodies. Several companies produce vaccines for this purpose and they contain rotavirus, coronavirus and K99 E. coli. If you have a problem with one or more of these agents, vaccinate twice the first year and then give annual booster shots just before the cows start calving to increase specific colostral antibodies. Scourguard 3K is an older vaccine with which most producers are familiar. Scour Bos is a new line of scour products. There are products to vaccinate calves with at birth (e.g., Calf Guard). Historically they have not been effective. If you have a choice, vaccinate the cows in late pregnancy. Calves should be vaccinated for Cl. perfringens C and D when they are 1 – 4 months old (note: vaccines may cause lumps at injection sites).
4. Oral or systemic antibodies. You can purchase oral antibodies specific for K99 E. coli and/or coronavirus. There are several manufacturers of K99 antibodies and one producer of a K99 + coronavirus antibody preparation. Give when the calf is born to supplement or enhance the colostral antibodies. You must have a specific diagnosis for these to be of value. It is expensive but effective if you have a diagnosis of one of these two agents. Clostridium perfringens C and D antibodies (= “antitoxin” since that is what the antibodies are neutralizing) are commercially available, and can be immediately administered subcutaneously to symptomatic animals. The dose can be repeated in sick animals until clinical signs resolve or they die. Susceptible animals on the farm should be given a dose of C and D antitoxin for prophylaxis. Use of C+ D antibodies is questionable unless there is a recurring problem and you are good at spotting affected animals early, or there is a large, laboratory-confirmed episode.
If you have a scour outbreak of calf scours
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Consult a veterinarian.
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Get a laboratory diagnosis on 2-3 fecal samples from untreated calves to find out what you are dealing with. If a calf dies and many others are sick, get fresh (ideally, untreated) carcasses to the laboratory for a workup.
* Isolate and treat affected animals - hydration and nursing is #1. Antibiotics may help, but only if the underlying cause is bacterial
* Revaccinate the cows that have not calved if the cows were previously vaccinated against the offending agent to boost their immunity and thus the colostral antibodies.
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Colostral supplements/enhancers to calves at birth if the agent is K99 or coronavirus.
* MLV vaccine to calves at birth if you are dealing with coronavirus or rotavirus AND the cows were not vaccinated for these agents. It will be better than nothing.
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Disperse newborns and their mothers as soon as possible.
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Clean, clean, clean, clean the pens, barns, etc.
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Special care to insure that calves nurse and get colostrum
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Causes of diarrhea in adult cattle
Outbreaks of diarrhea in adult cattle are uncommon, with two major infectious exceptions (salmonellosis, Johne's disease) and several related to nutrition (change in feed; grain overload) or other diseases (abomasal torsion; peritonitis; winter dysentery). Only the major ones will be covered here.
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Salmonellosis - see above
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Johne's disease (pronouned "Yo-nees") - This is a major headache in the dairy industry, and considered of minor import in the beef industry. It occurs in beef herds in Wyoming. USDA is taking an increasing interest in the disease in part because the agent can be found in milk, it infects various other species (sheep, goats, bison and occasionally horses), been linked to (but not proved to cause) a chronic idiopathic inflammatory bowel disease of people, Crohn's disease. Johne's is caused by a hardy bacterium belonging to the mycobacterial group that contains avian, human and bovine tuberculosis (TB), named Mycobacterium paratuberculosis, as well as the agent that causes human leprosy. These agents can live inside cells without being killed. This makes them less accessible to antibiotics. The ability to live inside cells is a property shared by other troublesome organisms, such as Salmonella, Brucella spp. and Rhodococcus equi. The mycobacteria are an especial problem since they have a peculiar waxy coat that make it hard for inflammatory cells and many antibiotics to kill them. Johne's is also called paratuberculosis, due to the similarities to TB (para = in comparison with; tuberculosis = well, you know. About 20% and 9% of dairy and beef herds in the US have infected carriers. The disease causes chronic insidious progressive weight loss and diarrhea. It is difficult to diagnose since the organism is hard and slow to grow in the laboratory. Serology and molecular techniques have improved our ability to make a diagnosis. Eliminating the disease requires:
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Protecting newborn animals from infection by being born and raised in a clean environment and fed milk free of M. paratuberculosis - in dairy operations this means separating calf from the dam and her feces at birth.
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Identifying and culling infected adult animals and - in beef herds - their most recent calf since they too are likely to be infected. Infected animals cannot be treated successfully, and most of the costs of the disease are due to clinically affected animals (which tend to test strongly positive). Tests for Johne's are imperfect, but with persistence the incidence of the disease in a herd can be made manageable. A report in 2006 in the J Am Vet Med Assoc outlined consensus recommendations for testing herds to eliminate Johne's disease. The USDA recently released a report of the incidence of Johne's disease nationally - the agent was found on almost 70% of all properties sampled (see below).
A vaccine is available but it causes bad injection site reactions - its use is controversial. The University of Wisconsin has the best laboratory in the country for diagnosis and advice on control, and has an excellent web site on the disease (for interest and gunners - information on these links will not be tested for).
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Winter dysentery - This is an apparently infectious disease of cattle most commonly seen in winter. It usually occurs as explosive outbreaks of diarrhea in adult cattle with up to 40% affected. It is purported to be due to coronavirus. Animals generally recover with or without treatment.
Some other important digestive tract diseases of cattle:
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Jejunal hemorrhage syndrome - This is a "new" disease which is important in some parts of the country, esp. in the dairy industry (Midwest; WA, ID, CA, WI, CO). It is also called 'bloody gut syndrome', 'dead gut' and 'enterotoxemia.' We had our first case of this in 2006, but don't have much experience of it since there are so few dairy cattle in WY. Cows colic acutely and die. Often they are found dead. Some pass blood clots in their stool as they go into shock. It does not appear readily transmissible in a herd. There is usually a 1 - 3 foot segment of lower bowel (jejunum) that is necrotic and in which the lumen is full of blood. The cause is being actively researched. Clostridia may be involved. Given the high case fatality rate (>70%) and our ignorance about cause, it is difficult at this time to suggest preventative measures.
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Bloat - The term means abdominal distension of the forestomach (almost always the rumen). There are various forms of the disorder (frothy, usually due to taking in excessive legumes [seen on leguminous pastures, such as alfalfa or clover]; grain bloat due to excessive intake of grains [in feedlots]; and obstructive or free gas bloat due to obstruction or holding an animal down so long that it cannot eructate). If marked and not relieved, the bloated rumen puts pressure on the lungs, animals can't breath and die in part of asphyxiation. Treatment is to pass a stomach tube to release gas or, failing that, to use a tube introduced into the left flank and rumen. Avoidance involves no sudden dietary changes, and adequate dietary fiber.
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Hardware disease - This is more correctly called traumatic reticuloperitonitis - inflammation of the reticulum and peritoneal lining of the abdominal cavity by sharp foreign bodies (nails, wire and needles) that are trapped in the reticulum. Cattle are indiscriminate feeders and often ingest sharp objects left lying around on the pasture or in pens. The anatomy of the reticulum causes them to become trapped there, and if they become lodged in the mucosa they can slowly work their way forward and through the wall of the abomasum. Prevention: don't be a slob; avoid leaving nails, wire and needles in pastures; ingested magnets help keep the metal in the lumen; large magnets on feed-handling equipment can get it out of processed feed. Treatment: surgery. A thorough necropsy also works, and guarantees no recurrence.
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Study guide
1. In addition to dehydration, there are at least two important physiological changes that occur when animals develop severe diarrhea, which are corrected with appropriate rehydration solutions. What are they?
2. Name an important difference between calfhood diarrhea due to rotavirus and that due to coronavirus?
3. How common is Johne's disease, and what does it cause?
4. When is the best time to vaccinate to avoid/minimize viral calf scours?
5. What is jejunal hemorrhage syndrome?
6. What complications occur as a result of salmonellosis in calves?
7. In one sentence, explain what you understand by the term "shock"
8. List 6 things you can do to minimize the risk of calf scours, other than vaccination.
9. What is the main difference between BVD in neonatal calves, and salmonellosis in the same age group, in terms of ability to cause diarrhea?
10. There is a higher morbidity rate due to enteric disease in dairy than in beef calves. Yet they have approximately the same rates of pneumonia. Why the difference in enteric disease?
NOTE: There are 2 graphs and 1 photo not seen in this post. Click on the link at the top of this page to view.
Dr. Donal O'Toole
Last updated: 02/01/2010
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ENTERIC DISEASES OF CATTLE
Lecturer: Dr. Donal O'Toole
Enteric diseases are those that affect the intestinal tract. Enteritis means inflammation of the intestines, specifically, the small intestine. Colitis is inflammation of the major portion of the large intestine (colon). The suffix –itis means inflammation, so typhlitis means inflammation of the cecum, rumenitis inflammation of the rumen, and so on. Enterocolitis is the term for inflammation of the small intestine and colon. Such inflammation leads to diarrhea (“scours”). Different infectious agents affect specific parts of the digestive tract. For example, rotavirus tends to affect the small intestine, coronavirus both large and small intestine, and pathogenic coccidia the large intestine primarily (in ruminant species).
Neonatal diarrhea (“calf scours”)
A “neonate” is a newborn infant. "Neonatal” generally refers to animals up to 1 month of age. Calf scours are among of the most common and costly diseases of cattle. It is the number 1 killer of dairy calves and the number 2 killer of beef calves (after respiratory infections, and when dystocia death loss is excluded).
Enteric disease, which includes diarrhea, is a major killer of diary calves, accounting for more than 40% of death loss in medium size (100 - 499 cow) operation.
Enteric disease accounts for 13% of death loss in beef cattle, ranking second to respiratory disease (primarily pneumonia) as a major cause of death.
About 10% of all dairy calves and 5% of all beef calves die of scours from all causes. Most cases are due to infectious agents, often occurring in combination. Indigestion, fever, heart failure and other non-infectious disease processes can also result in diarrhea as a clinical sign. Calves that have diarrhea have deficits in water and electrolytes. If diarrhea continues unchecked, calves become glucose deficient (hypoglycemic) and their blood becomes excessively acid (acidosis, due to loss of bicarbonate). These must be reversed if the animal is to survive.
Age: Most fatal cases of calf scours occur within the first 2 - 3 weeks after birth. Although outbreaks occur after 2 - 3 weeks of age, such calves are larger and better equipped to deal with the dehydration and survival rates go up dramatically. After ~3 months of age, diarrhea outbreaks are uncommon except for coccidiosis, a protozoan infection that is common as a clinical disease in weaned calves in late fall and winter months.
Infectious agents: Numerous viral, bacterial and protozoal agents that can cause scours in neonatal calves, lambs and foals. We will deal with calves, but realize that similar disease agents occur in lambs and foals. Those agents are:
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Viral: rotaviruses and coronaviruses
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Bacterial: E. coli, especially with K99 pili, Campylobacter jejuni, Salmonella spp., Clostridium perfringens, especially type C and D
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Protozoal: Eimeria spp. coccidia ("coccidiosis"; usually older calves; generally not a neonatal disease) and cryptosporidia.
In northern plains states, rotavirus, coronavirus, K99 E. coli, and cryptosporidia are the main agents that cause large scour outbreaks. The first 3 are more commonly associated with high death rates. Some of these pathogens are zoonotic (Salmonella spp., Cryptosporidium spp., and some enteropathogenic E. coli strains). Take care to protect yourself when handling calves with diarrhea or contaminated bedding.
Clinical signs:
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Diarrhea. The color of the stool is of little diagnostic importance. The presence of blood and mucus may help determine the site of inflammation. Blood that is bright red suggests hemorrhage is in the lower bowel (primarily large intestine). Dark red to black blood (= partly digested) indicates bleeding higher up the digestive tract, since it has opportunity to be degraded in the digestive process. The cause of diarrhea ranges from damage to the intestinal lining (mucosa), which prevents water absorption and fluid leakage into the lumen of the gut, to toxins (e.g. the exotoxin of K99 E. coli) that stimulate water excretion into the gut.
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Dehydration. As the animal loses fluids, they become dehydrated. The circulatory system begins to fail from lack of volume. This leads to:
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Shock (inadequate perfusion volume in the circulation) and hypothermia, and finally:
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Death, and the welcoming arms of God.
Calf Severity % Dehydration Features What to do
Mild <5% body weight - Calf can stand
- Skin tents for <4 sec
- Calf sucks from bottle - Leave cow on cow
- Alternate milk electrolyte feedings via bottle or stomach tube; at least 2 milk feedings + 2 electrolyte feedings daily for 80-100 lb calf
Moderate 5-7% body weight - Calf lying down (sternal)
- Skin tents for 5 sec
- Limbs cold
- Mouth warm & sticky
- Eyes slightly sunken - Move calf to warm area
- Stomach tube and feed 1/2 gallon warm high energy electrolyte solution (e.g. Entrolyte) every 2-4 hours
Marked >9% body weight - Calf lying down (lateral)
- Semi-comatose
- Eyes markedly sunken
- Mouth dry & cold - Veterinary care
(needs I/V fluids to survive)
With most of these agents, a low-grade fever may be present early on. As the calves dehydrate, they can no longer maintain core body temperatures and they become hypothermic (below normal). The degree of dehydration can be estimated by the skin tent test (above)
Transmission: Spread is by the fecal-oral route, i.e. from infected fecal material being ingested, usually during nursing from contaminated udders and teats. Adults in the herd are the initial source of most agents, with some exceptions. As more calves become infected, the level of contamination and rate of spread increases. Scours are usually seen in the latter half of the calving season due to a buildup of organisms in manure, barns, sheds, corrals and bedding.
Factors that increase the odds of calf scours:
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Management. Crowding, housing and poor sanitation (esp. wet or damp bedding and lying on manure).
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Failure of passive transfer (FPT) of colostrum. This is especially true of first calf heifers due to poor mothering instincts plus they give less milk. These animals may have not been exposed to the agents sufficiently and have less antibody to that agent. Poor nutrition = less colostrum. Cold stress decreases absorption of antibodies. Dystocia reduces the calf's interest in feeding, and delays nursing. If you decide to use commercial sources of colostrum, be aware that they differ markedly in quality. For example, a comparison between feeding with natural colostrum and two commercial sources (Land O'Lakes colostrum replacement, Land O'Lakes Inc; Immu-Start 50 - Imu-Tek Animal Inc.) found the following:
Group Serum IgG (mg/dL) Percent calves with adequate immunity
Colostrum 2,720 ± 1,020 90%
Land O'Lakes 1,160 ± 290 81%1
Immu-Start 700 ± 220 10%
1: Note: 95% of calves fed two rather than one package of this product had adequate immunity
Source: Foster et al: 2006, JAMVA 229 (8): 1282 - 1285
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Weather. Stress from severe cold, overcrowding or wet conditions may increase cortisol levels and lead to suppression of the immune system.
Human error is a big factor in many outbreaks, due to concentration of livestock creating many of the above factors.
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Common causes of diarrhea in calves
Coronavirus: Common and deadly, resulting in losses of up to 10%. It causes severe loss of cells covering villi of the small intestine and the surface of the large intestine, resulting in inability to absorb fluids and nutrients. It is generally seen in calves 1-2 weeks. It occurs as early as 3 days and as late as 1 month.
Rotavirus. It is a common cause of scours. Rotaviruses cause diarrhea in man, foals and other animals, but each is species-specific so the calf agent doesn’t infect people. Generally, rotaviral diarrhea is milder than coronavirus infection. It is not highly fatal unless mixed infections with more than one agent occur. It is destroys cells in the small intestine only, and then only at the tips of villi. It can occur up to about 3 months of age. It is a big problem in first week of life. Such calves are small and vulnerable to the complications of diarrhea. Rotaviral diarrhea tends to occur for a shorter period and earlier in a calf’s life than coronavirus, but they do overlap temporally, often in one outbreak. This is a hardy virus that survives well in the environment.
Bovine viral diarrhea virus. On its own, in healthy calves, it causes transient illness with fever and mild diarrhea. It is a more serious problem when calves are born persistently infected. BVDV is covered in a separate lecture.
Escherichia coli. This genus-species contains hundreds of different strains of bacteria. Most are not pathogenic. Many are beneficial, like those that colonize the intestinal tract. The pathogenic ones come in three forms:
- K99+ and other enterotoxigenic E coli strains. It is specific for calves and lambs. The K99 antigen is a pilus on the bacterium which allows the organism to attach and colonize the mucosa of the small intestine, so that we see dense mats of bacteria adhering to the surface microscopically. The K99 strains have plasmids that code for a potent exotoxin (enterotoxin) that increases water secretion into the lumen of the gut, resulting in diarrhea. Incidence varies from year to year, but is can be controlled with vaccination. This is seen in calves <1 week old. This is the most common cause of “white scours.”
Attaching and effacing E. coli. (= AEEC). These are rare but becoming more of a problem. Most cases in calves older than 1 week.
Septicemic strains. Some strains of E. coli can penetrate the gut and spread via the blood to other organs where they cause pneumonia, joint infections, and encephalitis. The term colisepticemia is applied to these strains. They also may cause navel infections when they enter via the navel at the time of birth. Depending on the strain involved, calves can die quickly (~6 hours) of onset – often they are just found dead. These animals are difficult to save and require intensive veterinary treatment (I/V fluids; glucose; systemic antibiotics; bovine immunoglobulin).
Cryptosporidia. See parasitology notes. “Crypto” is a coccidian protozoal agent, although when we refer to coccidiosis in calves we are talking about the Eimeria genus of protozoa, and not crypto. It causes mild enteritis and is rarely fatal by itself. Mixed infections with other agents are common. Because of its life cycle, it is not seen in calves <5 days of old. It is zoonotic.
Coccidiosis. See parasitology notes. A protozoan agent that affects older calves, especially weaner calves in late fall and winter. Rarely a problem in the first month of age, although we have seen it cause fatal blood diarrhea and/or straining (tenesmus) in calves as young as 2 weeks.
Salmonellosis. This ubiquitous disease affects practically all species of vertebrates. It is mostly a problem in dairy operations, but we see it every year in Wyoming beef herds. It affects all ages. Clinical signs are most common in young, old, and debilitated animals, and in people. The CDC reports approximately 40,000 confirmed cases of salmonellosis annually; the estimated number of human cases of gastroenteritis due to salmonellosis in the US annually is 1.4 million, with ~300 deaths. The most commonly identified agent causing human salmonellosis is linked to poultry, poultry products, and eggs (Salmonella enterica serovar Enteritidis). Salmonella serovar Typhimurium, which infects cattle, is the second most common isolate from human cases. One strain of this organism is called Salmonella ser Typhimurium PT DT104. DT 104 has become an important food safety concern because of the increased incidence in both human and animal infections in the United States, as well as its resistance to multiple antimicrobials, including chloramphenicol, its veterinary analog florfenicol, as well as streptomycin, the sulfonamides, and ampicillin. When we get an isolate we send it to the public health laboratory in Cheyenne for typing so it can be compared to salmonellosis isolates from people – we’d had several hits where isolates match up. The most common sources of infection are contaminated food and water. Approximately 40% of all animal-origin feed additives (bone and fish meal) are contaminated with Salmonella spp. A survey of cattle feeding states in the United States for Salmonella spp in cattle feed lots revealed that 6.3% of 10,417 fecal samples were positive - another good reason, if you need one, why children (and adults) should treat fecal material with respect. Human sewage has also been tracked down as a source of infection in some herd outbreaks. Rodents, birds, and other animals spread infection through their feces and their carcasses.
There are two clinical forms of the disease in ruminants:
Enteric: Adults primarily show the enteric form. It is a big deal in horses, particularly when crowded and stressed. It is addressed in this course under enteric diseases of horses. In cattle it tends to remain an enteric disease and not get into the bloodstream. It is most often seen in cows at term. Horses by contrast can become septicemic. Cattle and horses can both be persistent, chronic carriers either with or without clinical signs of ill thrift.
Septicemic: Calves, lambs, and goat kids are especially vulnerable to septicemia. Failure of passive transfer, crowding, chilling, transport, and poor nutrition make young animals more susceptible to the disease. It generally occurs in calves 1 – 12 weeks old. Often they start with enteric signs (often with blood and mucus in stool), progressing to systemic disease with pneumonia, multiple joint infections (polyarthritis) and encephalitis-meningitis. Morbidity and mortality rates are high.
Veterinary treatment is required to save animals. In beef calves the simplest and safest practice may be to euthanize calves with clinical salmonellosis since it is difficult to know when a recovering animal has cleared the infection. The carrier state in cattle persists for as long as 10 weeks. Please DON’T knowingly sell calves that have had salmonellosis.
Clostridium perfringens type C and D. This rarely causes scour outbreaks. In most situations it is a problem that affects a small number of individuals (<5% death loss). We have seen situations where a herd of pregnant cows that have never been vaccinated for C and D are moved onto a new property, and a wreck with ~25% mortality in young calves ensures. More typically, losses occur in older (1 – 3 month old) calves, often the best in the bunch. Once calves show clinical signs, it is generally late to save them. The clinical course is rapid and calves are found dead. Less commonly, bloody scours are seen and calves exhibit abdominal pain (colic) and convulsions; you may see feces with what looks like pieces of wet paper in it. This is fibrin passed from necrotic guts. It may occur in vaccinated herds. The toxin produced by the organism causes severe necrosis and hemorrhage of the surface of the small intestine and proximal part of the large intestine, hence the common term for the disease, purplegut. You may hear the term enterotoxemia, but this should be reserved for type D Clostridium perfringens enteritis. The organism is a normal inhabitant of the calf’s small intestine. Factors triggering proliferation are poorly understood. Some properties in Wyoming have recurring problems with the disease, so we assume it is cycles between soil and gut/teats. Heavy feeds of milk or colostrum appear to precipitate disease. C. perfringens proliferates in the presence of starches and sugars in the small intestine. In mature cattle these are predominantly digested in the rumen, and not available to the C. perfringens. In pre-ruminant calves, nearly all feed bypasses the rumen and is digested in the abomasum (true stomach) and the small intestine, so starches are available. This, coupled with a normal intestinal flora that has not yet developed, provides a suitable environment for the C. perfringens to proliferate. Several factors contribute to this rapid proliferation. Primary among these are abrupt changes in feeding patterns, physical or environmental stress, nutritional deficiencies, and conditions that impair movement of the intestine (such as diarrhea due to other causes).
Purple gut in a calf. The intestines that are dark purple on right are necrotic (dead tissue). The pink tissues on left are more normal. Calves with this amount of damage in their intestines typically exhibit colic. Damage of this severity cannot be corrected even with prompt antibiotic treatment.
Control is obtained by vaccinating dams with C and D toxoid on two occasions, the last given ~2 weeks before parturition; vaccinate the dams annually thereafter. If you haven't done this, and start losing calves that are confirmed to be due to Clostridium perfringens C or D, your options are to give antibodies ("antitoxin") either orally or subcutaneously at birth, or to vaccinate the calves at birth. Calves should be re-vaccinated at 2 - 4 months.
Review of enteric clostridial diseases in cattle, from South Dakota State University
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Diagnosis of agents of scours: This requires laboratory assistance. Knowing the cause helps determine the best course of action, including what type of vaccine to use the following year. If you use a product and have seen a disease break, talk to your veterinarian about going to a different product.
Treatment: If a calf is scouring, regardless of the cause, rehydration is the most important treatment (see above):
Oral fluids/electrolytes: There are many oral fluid/electrolyte products on the market. They are mixed with warm water and given via esophogeal ("stomach") tube. Oral electrolyte solutions are formulated to replace lost water, replace electrolytes (potassium, sodium, chloride, bicarbonate), alkalinize the recipient, and provide nutritional support by giving dextrose. Bicarbonate is the best alkalinizing agent. An energy source (glucose, dextrose, glycine) is added to facilitate small intestinal uptake of electrolytes and to correct the hypoglycemia. The energy level in commercial formulations is insufficient to meet calves’ caloric demands and they can starve to death if food is withheld for over 48 hours. Commercial products vary in cost and quality. If an 80 lb calf is 5% dehydrated, it needs those ~4 lb back as fluid (1 lb approximately = 1 pint) so the deficit is 4 pints (~ 1 liter). This should be split about equally between milk and electrolytes. It is difficult to over-hydrate a calf, but be careful not to give it inhalation pneumonia by feeding too fast – split the feedings. OK, so a 100 lb calf that is 5% dehydrated needs how much fluid replacement?
Antimicrobials: Most cases will be viral or protozoal, agents that are not affected by them. So, these are not recommended unless you know you are dealing with specific bacteria, or suspect septicemia (very rapidly progressive collapse of the calf). Don’t kill remaining good bacteria in the gut unnecessarily.
Probiotics: These are microbial replacements to aid the gut. In nursing animals, those with Lactobacillus spp. may be helpful in reestablishment of normal gut bacteria. Can’t hurt, but may not help.
Warmth: Hypothermia is an important complicating factor in Wyoming. Warm water baths are best. Warming rooms, hair dryers and heating lamps also work if calves are not too cold.
Prevention:
1. Good management
Adequate nutrition of the dam
Good hygiene and sanitation
Reduce crowding
Decrease weather stress if possible
May want to change calving season if possible
2. Adequate colostrum.
This is tied to the cows’ nutrition and genetics. Don’t interfere too early with the bonding between the cow and her calf. The biggest problem will be with first-calf heifers. If the cow dies for some reason or will not allow the calf to nurse, giving natural or commercial colostrum will be required within the first few hours.
3. Vaccinate dams to increase specific antibodies. Several companies produce vaccines for this purpose and they contain rotavirus, coronavirus and K99 E. coli. If you have a problem with one or more of these agents, vaccinate twice the first year and then give annual booster shots just before the cows start calving to increase specific colostral antibodies. Scourguard 3K is an older vaccine with which most producers are familiar. Scour Bos is a new line of scour products. There are products to vaccinate calves with at birth (e.g., Calf Guard). Historically they have not been effective. If you have a choice, vaccinate the cows in late pregnancy. Calves should be vaccinated for Cl. perfringens C and D when they are 1 – 4 months old (note: vaccines may cause lumps at injection sites).
4. Oral or systemic antibodies. You can purchase oral antibodies specific for K99 E. coli and/or coronavirus. There are several manufacturers of K99 antibodies and one producer of a K99 + coronavirus antibody preparation. Give when the calf is born to supplement or enhance the colostral antibodies. You must have a specific diagnosis for these to be of value. It is expensive but effective if you have a diagnosis of one of these two agents. Clostridium perfringens C and D antibodies (= “antitoxin” since that is what the antibodies are neutralizing) are commercially available, and can be immediately administered subcutaneously to symptomatic animals. The dose can be repeated in sick animals until clinical signs resolve or they die. Susceptible animals on the farm should be given a dose of C and D antitoxin for prophylaxis. Use of C+ D antibodies is questionable unless there is a recurring problem and you are good at spotting affected animals early, or there is a large, laboratory-confirmed episode.
If you have a scour outbreak of calf scours
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Consult a veterinarian.
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Get a laboratory diagnosis on 2-3 fecal samples from untreated calves to find out what you are dealing with. If a calf dies and many others are sick, get fresh (ideally, untreated) carcasses to the laboratory for a workup.
* Isolate and treat affected animals - hydration and nursing is #1. Antibiotics may help, but only if the underlying cause is bacterial
* Revaccinate the cows that have not calved if the cows were previously vaccinated against the offending agent to boost their immunity and thus the colostral antibodies.
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Colostral supplements/enhancers to calves at birth if the agent is K99 or coronavirus.
* MLV vaccine to calves at birth if you are dealing with coronavirus or rotavirus AND the cows were not vaccinated for these agents. It will be better than nothing.
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Disperse newborns and their mothers as soon as possible.
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Clean, clean, clean, clean the pens, barns, etc.
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Special care to insure that calves nurse and get colostrum
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Causes of diarrhea in adult cattle
Outbreaks of diarrhea in adult cattle are uncommon, with two major infectious exceptions (salmonellosis, Johne's disease) and several related to nutrition (change in feed; grain overload) or other diseases (abomasal torsion; peritonitis; winter dysentery). Only the major ones will be covered here.
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Salmonellosis - see above
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Johne's disease (pronouned "Yo-nees") - This is a major headache in the dairy industry, and considered of minor import in the beef industry. It occurs in beef herds in Wyoming. USDA is taking an increasing interest in the disease in part because the agent can be found in milk, it infects various other species (sheep, goats, bison and occasionally horses), been linked to (but not proved to cause) a chronic idiopathic inflammatory bowel disease of people, Crohn's disease. Johne's is caused by a hardy bacterium belonging to the mycobacterial group that contains avian, human and bovine tuberculosis (TB), named Mycobacterium paratuberculosis, as well as the agent that causes human leprosy. These agents can live inside cells without being killed. This makes them less accessible to antibiotics. The ability to live inside cells is a property shared by other troublesome organisms, such as Salmonella, Brucella spp. and Rhodococcus equi. The mycobacteria are an especial problem since they have a peculiar waxy coat that make it hard for inflammatory cells and many antibiotics to kill them. Johne's is also called paratuberculosis, due to the similarities to TB (para = in comparison with; tuberculosis = well, you know. About 20% and 9% of dairy and beef herds in the US have infected carriers. The disease causes chronic insidious progressive weight loss and diarrhea. It is difficult to diagnose since the organism is hard and slow to grow in the laboratory. Serology and molecular techniques have improved our ability to make a diagnosis. Eliminating the disease requires:
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Protecting newborn animals from infection by being born and raised in a clean environment and fed milk free of M. paratuberculosis - in dairy operations this means separating calf from the dam and her feces at birth.
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Identifying and culling infected adult animals and - in beef herds - their most recent calf since they too are likely to be infected. Infected animals cannot be treated successfully, and most of the costs of the disease are due to clinically affected animals (which tend to test strongly positive). Tests for Johne's are imperfect, but with persistence the incidence of the disease in a herd can be made manageable. A report in 2006 in the J Am Vet Med Assoc outlined consensus recommendations for testing herds to eliminate Johne's disease. The USDA recently released a report of the incidence of Johne's disease nationally - the agent was found on almost 70% of all properties sampled (see below).
A vaccine is available but it causes bad injection site reactions - its use is controversial. The University of Wisconsin has the best laboratory in the country for diagnosis and advice on control, and has an excellent web site on the disease (for interest and gunners - information on these links will not be tested for).
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Winter dysentery - This is an apparently infectious disease of cattle most commonly seen in winter. It usually occurs as explosive outbreaks of diarrhea in adult cattle with up to 40% affected. It is purported to be due to coronavirus. Animals generally recover with or without treatment.
Some other important digestive tract diseases of cattle:
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Jejunal hemorrhage syndrome - This is a "new" disease which is important in some parts of the country, esp. in the dairy industry (Midwest; WA, ID, CA, WI, CO). It is also called 'bloody gut syndrome', 'dead gut' and 'enterotoxemia.' We had our first case of this in 2006, but don't have much experience of it since there are so few dairy cattle in WY. Cows colic acutely and die. Often they are found dead. Some pass blood clots in their stool as they go into shock. It does not appear readily transmissible in a herd. There is usually a 1 - 3 foot segment of lower bowel (jejunum) that is necrotic and in which the lumen is full of blood. The cause is being actively researched. Clostridia may be involved. Given the high case fatality rate (>70%) and our ignorance about cause, it is difficult at this time to suggest preventative measures.
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Bloat - The term means abdominal distension of the forestomach (almost always the rumen). There are various forms of the disorder (frothy, usually due to taking in excessive legumes [seen on leguminous pastures, such as alfalfa or clover]; grain bloat due to excessive intake of grains [in feedlots]; and obstructive or free gas bloat due to obstruction or holding an animal down so long that it cannot eructate). If marked and not relieved, the bloated rumen puts pressure on the lungs, animals can't breath and die in part of asphyxiation. Treatment is to pass a stomach tube to release gas or, failing that, to use a tube introduced into the left flank and rumen. Avoidance involves no sudden dietary changes, and adequate dietary fiber.
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Hardware disease - This is more correctly called traumatic reticuloperitonitis - inflammation of the reticulum and peritoneal lining of the abdominal cavity by sharp foreign bodies (nails, wire and needles) that are trapped in the reticulum. Cattle are indiscriminate feeders and often ingest sharp objects left lying around on the pasture or in pens. The anatomy of the reticulum causes them to become trapped there, and if they become lodged in the mucosa they can slowly work their way forward and through the wall of the abomasum. Prevention: don't be a slob; avoid leaving nails, wire and needles in pastures; ingested magnets help keep the metal in the lumen; large magnets on feed-handling equipment can get it out of processed feed. Treatment: surgery. A thorough necropsy also works, and guarantees no recurrence.
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Study guide
1. In addition to dehydration, there are at least two important physiological changes that occur when animals develop severe diarrhea, which are corrected with appropriate rehydration solutions. What are they?
2. Name an important difference between calfhood diarrhea due to rotavirus and that due to coronavirus?
3. How common is Johne's disease, and what does it cause?
4. When is the best time to vaccinate to avoid/minimize viral calf scours?
5. What is jejunal hemorrhage syndrome?
6. What complications occur as a result of salmonellosis in calves?
7. In one sentence, explain what you understand by the term "shock"
8. List 6 things you can do to minimize the risk of calf scours, other than vaccination.
9. What is the main difference between BVD in neonatal calves, and salmonellosis in the same age group, in terms of ability to cause diarrhea?
10. There is a higher morbidity rate due to enteric disease in dairy than in beef calves. Yet they have approximately the same rates of pneumonia. Why the difference in enteric disease?
NOTE: There are 2 graphs and 1 photo not seen in this post. Click on the link at the top of this page to view.
Dr. Donal O'Toole
Last updated: 02/01/2010
