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Written by Administrator
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Sunday, 14 September 2008 20:54 |
Liver disease has not been widely recognized in camelids (alpacas and llamas). Although fatty liver disease is often discussed or observed during necropsy examination, primary liver diseases have been infrequently diagnosed. Recent clinical data suggest that the cause of fatty liver disease may have been overlooked in many camelids. Because camelids are not used for intensive meat or milk production in North America and they usually are not overworked by riding or carting, theories postulated for onset of liver disease in other livestock species may not apply to camelids. Historical informationSick camelid syndrome refers to a camelid that demonstrates depression, lethargy, increased periods of recumbency, and decreased appetite. Occasionally diarrhea or abdominal discomfort are observed. The results of physical examination fail to reveal any abnormalities except that the animal may be more tender to palpation of the abdomen than normal. In my opinion, laboratory testing of these animals is obligatory because of the stoic nature of these patients. A camelid may not show clinical signs of severe disease in a desperate attempt not to be singled out from the herd as a "weakened" animal by potential predators. The most important information to be gained is a detailed account of the animals recent lifestyle. Any changes should be discussed (nutrition, herd mates, feed bags, traveling to shows / sales / new farm, breeding activity, importation and quarantine, de-worming and vaccines or lack thereof, obesity, heat stress, emaciation, etc). Most cases of liver disease are found to be caused by or exacerbated by stress. Physical examination and clinical signsA thorough physical examination is required to rule-out common causes of illness in camelids: parasites, GI disturbance, C3 ulcer, starvation or malnutrition, social hierarchy, dental problems (tooth root abscess, malocclusion, etc), neurologic disease (meningeal worm, trauma, infection), pneumonia, etc. Rectal temperature, heart rate and rhythm, respiratory rate and pattern, C1 motility frequency and pattern, fecal consistency / color, urine color / clarity, peripheral lymph node palpation, and oral examination are the minimum veterinary data base. I routinely perform a complete blood cell count and serum biochemistry profile. Although viral and bacterial hepatitis are occasionally diagnosed in camelids, secondary bacterial infection is most common. Of particular concern is invasion of clostridia. Therefore, the complete blood cell count is evaluated for evidence of bacterial infection and the PCV and total protein examined. I have found that a rising PCV in the presence of a falling T.P. is a grave prognostic indicator. Also, I use blood immunoglobulin concentration as a screening tool to evaluate immune system status. Etiologic investigations: diagnosis?Diagnosis of the cause of liver disease in camelids can be an exercise in frustration. Histopathology (microscopic examination of liver tissue by means of liver biopsy) usually is not specific: hepatic lipidosis, biliary hyperplasia, lymphocytic plasmacytic hepatitis are common findings. Occasionally cholangiohepatitis (infection of the bile ducts) or cholestasis (obstruction to bile flow) is diagnosed from biopsy. Although histopathology often does not provide a definitive diagnosis, the information gained is well worth the effort. Because few specific liver diseases have been described for camelids, differential diagnoses should be broad in range: metabolic (e.g., fatty liver, cirrhosis), parasitic (e.g., liver flukes), toxic (e.g., mycotoxin, endotoxin, clostridium spp), bacterial (e.g., Salmonella spp, Clostridial spp, E coli), viral (e.g., adenovirus), fungal (e.g., Coccidioides imitis), and tumors or cancer (e.g., adenocarcinoma). Treatment strategyTreatment is directed at supportive care unless a more specific diagnosis can be determined. Antibiotics, anti-inflammatory drugs, fluid therapy (I prefer oral fluids when possible), glucose supplementation, and pain therapy are useful for treatment of severe liver disease. Insulin therapy must be used judiciously so that a harmful decrease in blood glucose does not occur. When used, intravenous fluids must be administered cautiously because camelids readily develop low blood protein with liver disease. Anti-ulcer prophylaxis is critical to prevent clostridial overgrowth. Clostridial antitoxins or vaccination may be useful to bolster immunity. The most critical factor for treatment of camelids with liver disease is to keep them eating. If appetite is suppressed, transfaunation (administration of the rumen fluid from a cow into the stomach) is a potent appetite stimulant. Other options include bacterial supplements products (such as probios), yogurt, B-complex vitamins, use of a companion animal, and offering a variety of feeds including frequent grazing. Camelids may lay down and refuse to get up if isolated in a stall. These animals should be walked, grazed, and a companion animal kept with them to prevent this cycle from starting. Reversing liver disease in camelids by increasing the energy density of the diet is the most successful part of treatment. A glucose enriched electrolyte water should be available at all times. Energy density may be increased in the diet by supplementing sweetfeed, dried molasses, syrup, etc. These supplements should be made available until liver enzymes have returned to normal. Prevention of liver diseaseMost cases of liver disease can not be readily explained. Therefore, recommendations for prevention are difficult. Probably, the most significant factor in the prevention of liver disease is to prevent sustained stress. Hepatic lipidosis is the most common consequence even in relatively thin animals. To prevent the development of these adverse effects, the environment in which the animals are moved should be as free from stress as possible, animals should be vaccinated with 7-way or 8-way clostridial vaccines, high quality grass hay or grass should be available at all times, and a trace mineral mix should be available. If the feed source has changed recently, a feed analysis is indicated to determine if the feed is low in digestible energy. The best indicator of the adequacy of the diet is to analyze mineral content in liver biopsies.
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