Veterinary Medicine - October 2007 - (Page 646)

Toxicology Brief PEER-REVIEWED metal toxicosis, infectious diseases (e.g. Clostridium species infection, infectious canine hepatitis, systemic fungal infections), and massive ischemia (e.g. arterial or venous occlusion). HEPATIC HISTOLOGIC LESIONS Histologic examination of liver biopsy samples reveals hepatocellular fatty vacuolation, hepatic necrosis, periportal necrosis, portal fibrosis, and perivenular necrosis and inflammation. Bile duct proliferation is present, and bile canaliculi may be plugged with bile casts.4,13,15-18 /mc/page.do?sitePageId=33930. Aflatoxins can be identified in urine, but metabolites are quickly cleared from the body, making postexposure detection difficult.19 TREATMENT Because no specific antidote for aflatoxins is available, treatment is aimed at supportive care and the management of specific hematologic and biochemical derangements (Table 1). CBC, SERUM CHEMISTRY, AND CLOTTING PROFILE FINDINGS Patients may have mild to moderate anemia and, in cases of disseminated intravascular coagulation (DIC), may be thrombocytopenic. Hematologic parameters are otherwise unremarkable. Liver enzyme activities (alanine transaminase, alkaline phosphatase, aspartate transaminase, gamma-glutamyltransferase) and total bilirubin concentrations are elevated, and cholesterol and albumin concentrations are decreased. Coagulation profiles are often markedly abnormal, with prolonged activated partial thromboplastin times and prothrombin times and decreased antithrombin and protein C concentrations.4,13,18 FOOD OR TISSUE ANALYSIS Consider aflatoxicosis in any dog presenting with signs of acute liver failure, especially when the history is suggestive of a toxin (e.g. multiple dogs in same household affected, recent change in food). Since clinical signs are nonspecific for aflatoxicosis, a definitive diagnosis requires analyzing suspect food or identifying toxins in tissue samples. Several veterinary diagnostic laboratories offer qualitative or quantitative tests for aflatoxin in feed. Tissue analysis is less available. A list of accredited diagnostic laboratories is provided online by the American Association of Veterinary Laboratory Diagnosticians at www.aavld.org Detoxification Aflatoxins typically do not produce signs of toxicosis until after they have been absorbed from the gastrointestinal tract. So unless the dog has a recent history of ingestion of a known aflatoxin-contaminated food (which is rarely the case), emetics and other gastrointestinal decontamination methods are not indicated. Once absorbed, aflatoxins are rapidly metabolized in the liver. Interaction with cytochrome p450 results in toxic metabolites that are then conjugated with glutathione (GSH). TABLE 1 Treatment Considerations in Dogs with Aflatoxicosis Therapeutic Goal Detoxify to augment aflatoxin metabolism and excretion Treat hydration, correct electrolyte and acid-base imbalances, and lower serum ammonia concentrations Control hemorrhage Form of Treatment Administer agents such as N-acetylcysteine, S-adenosylmethionine, silymarin, and vitamin E. Administer colloids initially, and continue fluid therapy with isotonic crystalloids supplemented with electrolytes and dextrose as needed. Administer fresh whole blood or fresh frozen plasma, vitamin K, packed red blood cells, and bovine hemoglobin glutamer-200 as needed. Administer metronidazole in combination with amoxicillin, ampicillin, cephalexin, or cefadroxil. Administer an antiemetic such as metoclopramide or dolasetron and gastrointestinal protectants such as sucralfate and famotidine. Administer lactulose, neomycin sulfate, metronidazole, or flumazenil. Feed a balanced diet; avoid protein-restricted diets except in cases of hepatoencephalopathy. Continued on page 647. Prevent bacteremia or sepsis Stop vomiting, treat ulcers, and decrease acid in the gastrointestinal tract Control hepatoencephalopathy Provide adequate nutrition 646 October 2007 VETERINARY MEDICINE http://www.aavld.org/mc/page.do?sitePageId=33930 http://www.aavld.org/mc/page.do?sitePageId=33930

Table of Contents Feed for the Digital Edition of Veterinary Medicine - October 2007

Veterinary Medicine - October 2007 Contents Leading Off The Veterinary Medicine Interview: Dr. Kevin Fitzgerald Toxicology Brief Idea Exchange Animal Sheltering in the United States: Yesterday, Today, and Tomorrow The Euthanasia Problem Offer Basic Behavior Counseling for Every Pet at Every Visit Promote and Perform Early Spaying and Neutering Assist Owners in Selecting the Best Pets for their Lifestyles Champion Animal Welfare in Your Community CE Form Product Review Advertiser Index Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - October 2007

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