Fungal Toxicosis (Aspergillus flavus, A. parasiticus, Penicillium puberulum Fungi) in Dogs

Aspergillus flavus, Aspergillus parasiticus, and Penicillium puberulum are varieties of fungus that produce a potent classification of mycotoxin called an aflatoxin. Dogs are most often exposed to the toxin through foods made with contaminated grains or vegetables, although aflatoxins can also be transmitted through dairy and egg products if the animals that produced them ate infested grains. Aflatoxins cause severe damage to the liver, and prognosis is generally poor even with early and aggressive treatment.

Aspergillus flavus, Aspergillus parasiticus, and Penicillium puberulum are varieties of fungus that produce aflatoxins, a class of mycotoxin that can cause severe damage to the liver if ingested.

Symptoms of aflatoxicosis are caused by the damage to the liver and are identical to liver failure from other sources such as drug toxicity or heavy metal poisoning. 

• Cancer of the liver
• Confusion
• Diarrhea
• Excessive need to urinate
• Excessive thirst
• Internal hemorrhage
• Jaundice
• Lethargy
• Lesions on liver
• Loss of appetite
• Reduced clotting factor in blood
• Secondary infections
• Vomiting
• Weakness
• Weight loss
• Sudden death

Types

There are four major aflatoxins caused by these fungi; B1, B2, G1, and G2. Of the four, B1 is the most hepatotoxic and has the most potential to induce cancer of the liver. Depending on the volume and duration of contamination ingested the effects of aflatoxicosis can be diverse in severity and duration. Larger concentrations of ingested contaminates can cause symptoms to develop within 24 hours, whereas lower concentrations can take much longer for symptoms to emerge.

Aspergillus flavus, Aspergillus parasiticus, and Penicillium puberulum are varieties of fungus that can infect improperly stored staple foods. Once they have invaded the crops they often produce a potent classification of mycotoxin called an aflatoxin. Aflatoxins, once ingested, are rapidly metabolized in the liver, causing damage to the liver. The swiftness and severity of the damage done to the liver depends on the volume of contamination and the duration of exposure.

Although aflatoxins are a byproduct of a fungus that blights mainly plants, they can also contaminate the milk or eggs of farm animals that are exposed to them and be transferred that way as well.

In order to make a diagnosis your veterinarian will ask for a full history of the animal, as well as a general physical exam. A complete blood count, biochemistry profile, and urinalysis are likely to be ordered to discover the underlying cause of the symptoms. Your veterinarian will likely see liver activity and bilirubin concentrations elevated and cholesterol and albumin concentrations lowered, and may request a sample of your dog food to submit to a veterinary diagnostic toxicologist. A large sample is recommended, and it is helpful to have the package label with the product code and use-by date. When the liver breaks down aflatoxin the resulting metabolites can sometimes be detected in the urine, liver, kidney or milk of the infected animal as well if they have ingested any of the tainted food within the last 48 hours. If histologic lesions are found on the liver during either necropsy or biopsy they may help to confirm an aflatoxin diagnosis. Further confirmation would be obtained by submitting liver tissue samples or serum samples to test for aflatoxins.

There is no specific antidote to aflatoxins to date, so treatment is aimed at supportive care and the management of specific symptoms. An IV with fluids and electrolytes is likely to be set up to counteract dehydration and lower serum and ammonia concentrations and whole blood may be administered if there is internal hemorrhaging. An antiemetic may also be administered to reduce instances of vomiting as well as an antacid to decrease acid in the gastrointestinal tract. There are some medications and supplements that might augment your pet’s metabolism to facilitate the excretion of the toxins. Some possibilities that your veterinarian may recommend are:

• L-Carnitine – An amino acid derivative manufactured mainly in the liver that assists in fatty acid transportation
• Milk thistle – This natural supplement enhances GSH production and prevents some toxins from being bioactivated
• N-acetylcysteine – Beneficial for liver blood flow, oxygen extraction and is thought to replenish stores of an important natural antioxidant, Glutathione (GSH)
• S-adenosylmethionine (SAMe) – A super nutrient that increases the availability of the precursors required for GSH synthesis
• Vitamin E – A fat-soluble vitamin that may counteract the formation of the lipid peroxides that cause damage to the cell membranes

When you first bring your pet home it is best to have a comfortable and quiet space for your companion to recuperate with plenty of access to unpolluted food and clean water. It is important not to give your pet any medications without the approval of your veterinarian as some medications may interfere with the function of the liver and slow the excretion of the toxin, which may remain in the bloodstream for one to two weeks. Even with aggressive treatment aflatoxicosis is often fatal, and dogs that do recover will need to have their liver function monitored as they are more prone to developing neoplastic hepatic disorders and chronic liver disease.