Toxicology Brief: The critical care of aflatoxin-induced liver failure in dogs - Veterinary Medicine
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Toxicology Brief: The critical care of aflatoxin-induced liver failure in dogs


VETERINARY MEDICINE


The recommended dosage in dogs is 17 to 20 mg/kg given orally once a day as needed for weeks to months.29,30 Denosyl (Nutramax Laboratories) and Zentonil (Vétoquinol) are SAMe veterinary products that each offer three tablet sizes. Ideally, these products should be given on an empty stomach to increase absorption.31,32

  • Milk thistle (silymarin). The silybin-phosphatidylcholine complex in silymarin enhances GSH production and prevents bioactivation of certain toxins. Silymarin may also protect normal hepatocytes, promote the regeneration of hepatocytes, and act as a free-radical scavenger and antioxidant.33 Specifically, silymarin has been reported to have hepatoprotective effects against aflatoxicosis in chickens and rats.34,35

A standard therapeutic dosage for silymarin has not been established in dogs; recommendations range from 7 to 15 mg/kg/day (based on human data) to 50 to 150 mg/kg/day (based on Amanita phalloides hepatotoxicoisis in dogs).30 Nutramax Laboratories offers the oral veterinary product Marin (silybin/vitamin E/zinc) in two tablet sizes that contain either 24 or 70 mg silybin. The product information for Marin indicates a low mg/kg dose of silybin; instructions are given for weight ranges with doses varying from about 1.5 to 4.5 mg/kg once a day depending on a dog's size.36 If a higher dose is desired, Marin would have to be administered extra-label. Although Marin also contains zinc and vitamin E, the zinc content in the product is low and the safety margin for vitamin E is high.

Denamarin (Nutramax Lab o ra tories) is also available and contains a combination of SAMe and silybin.

  • Vitamin E. Vitamin E is a fat-soluble vitamin that may have a protective effect in aflatoxin exposure by counteracting the formation of lipid peroxides. Vitamin E supplementation in rabbits fed aflatoxin resulted in fewer and less severe changes in liver enzymes and other biochemical parameters as compared with a control group.37 Because of biliary obstruction, oral absorption of vitamin E may be decreased in aflatoxicosis.

The recommended dosage is 100 to 400 IU given orally twice a day.38 Marin contains vitamin E and comes in two tablet sizes that contain 105 or 300 IU vitamin E.36
  • L-carnitine. L-carnitine is an amino acid derivative synthesized primarily by the liver. It is involved in fatty acid transportation and mitochondrial function. A study of chronic aflatoxicosis in quail found enhanced antioxidant effects with L-carnitine supplementation.39 L-carnitine helps mobilize fatty acids in cats with hepatic lipidosis, but it is unknown whether it has similar activity in dogs with aflatoxicosis.40 The recommended dosage in cats is 50 to 100 mg/kg given orally once a day for two to four weeks.41
  • Others. Other nutraceuticals that may be beneficial in aflatoxin-induced liver disease include zinc, ursodeoxycholic acid (contraindicated in patients with biliary obstruction), phosphatidylcholine, and vitamins C and A.37,42

Fluid support

Patients with liver failure often require fluid therapy to treat dehydration from fluid loss, correct electrolyte and acid-base imbalances, lower serum ammonia concentrations, and reduce the risk of DIC. Hypovolemia and hypoperfusion are common in liver failure; contributing factors include hemorrhage from coagulation abnormalities, reduced colloidal osmotic pressure, peritoneal effusions, and water loss from vomiting or diarrhea. Initial resuscitation with colloids may be advisable (e.g. dextran-70, hetastarch, or fresh frozen plasma). Continuing fluid therapy in patients with acute liver failure may consist of isotonic crystalloids supplemented with electrolytes and dextrose as needed. Monitor the patient's acid-base status and electrolyte and blood glucose concentrations regularly, and adjust fluids accordingly. If hypernatremia is present, one-third to one-half strength saline solution is recommended.43


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Source: VETERINARY MEDICINE,
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