Poisoning by mold toxins in dogs (Mycotoxicosis)

  • Occurrence: very rare
  • Location of disease: General/Whole body
Author: Dr. med. vet. Gisa Löwe | Last modified: 10.08.2026
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When to visit the vet?

Non-urgent see a veterinarian within 2–3 days

?

If the condition worsens / symptoms persist, consult a veterinarian.

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Definition

Mycotoxicosis in dogs is a condition caused by the ingestion of toxic substances produced by certain fungi. These fungal toxins can cause severe health problems and require immediate medical treatment.

The most important facts at a glance

Mycotoxicosis in dogs is caused by the consumption of mycotoxins produced by fungi such as Aspergillus, Fusarium, and Penicillium. These toxins are often found in spoiled food and feed that has been improperly stored. Ingestion can occur through moldy feed or through food stored in warm, humid environments. Different mycotoxins, such as aflatoxins and trichothecenes, lead to various health problems, ranging from liver damage to neurological symptoms.

Symptoms of mycotoxicosis in dogs include increased salivation, vomiting, diarrhea, loss of appetite, lethargy, tachycardia, polydipsia, jaundice, and polyuria. In severe cases, respiratory distress, ataxia, tremors, and epileptiform seizures may occur. Diagnosis requires a thorough medical history and laboratory tests to detect liver or kidney damage. Specific tests for mycotoxins in blood or urine can confirm the diagnosis, while imaging procedures help rule out other causes.

Treatment should begin immediately and includes stopping the intake of contaminated food, intravenous fluids to treat dehydration, medications for vomiting and diarrhea, and, if necessary, anticonvulsants for neurological symptoms. The prognosis depends on the type and amount of mycotoxins ingested as well as the speed of treatment. Preventive measures include proper storage of feed and food, regular checks for mold, and the use of certified feed. In this way, pet owners can significantly reduce the risk of mycotoxicosis.

Causes

Mycotoxins are secondary metabolites produced by various fungal species. These toxins can occur in many environmental sources, particularly in contaminated food and feed. The most common fungi that produce mycotoxins include Aspergillus, Fusarium, and Penicillium. These fungi can grow on grains, nuts, fruits, and other organic materials.

Ingestion of mycotoxins typically occurs through contaminated food. Dogs can be at risk through consumption of moldy food or food that has been improperly stored. Mold thrives in warm, humid environments, which increases the risk of contamination, especially with improper feed storage.

Another important factor is the type of mycotoxin. There are numerous mycotoxins, including aflatoxins, ochratoxins, trichothecenes, and zearalenone, each with different toxic effects. Aflatoxins, for example, are known for their liver-damaging properties, while trichothecenes can be neurotoxic.

Symptoms

Rare symptoms:

The symptoms of mycotoxicosis in dogs can vary depending on the type and amount of mycotoxins ingested. The most common symptoms include vomiting, diarrhea, lethargy, and loss of appetite. These symptoms can occur acutely and worsen rapidly.

In cases of severe poisoning, neurological symptoms such as tremors, seizures, and coordination disorders may occur. These signs are particularly concerning as they can indicate an impairment of the nervous system. Liver damage is also possible, manifesting as jaundice, increased thirst, and increased urination.

Long-term exposure to mycotoxins can lead to chronic health problems, including liver failure, kidney damage, and a weakened immune system. Early detection and treatment are therefore crucial to avoid permanent damage.

Therapy

Treatment of mycotoxicosis in dogs typically requires immediate medical intervention. The first step is to stop the intake of the contaminated source. This can be done by removing the affected food or by inducing vomiting in the dog if ingestion occurred recently.

Supportive treatment is crucial for recovery. This includes intravenous fluids to treat dehydration and electrolyte imbalances, as well as medications to control vomiting and diarrhea. In severe cases, a blood transfusion may be necessary to support damaged organs.

If neurological symptoms are present, anticonvulsants may be used to control seizures. Hepatoprotective medications and supplements may also be prescribed to support liver function and promote regeneration.

Treatment should be monitored by a veterinarian to track progress and adjust therapy as needed. Continuous monitoring of organ function is crucial to avoid complications.

Prognosis and follow-up care

The prognosis of mycotoxicosis in dogs depends on several factors, including the type and amount of mycotoxins ingested, the speed of treatment, and the dog’s overall health condition. Early detection and treatment significantly improve the prognosis.

In cases of mild to moderate poisoning and timely treatment, the prognosis is generally good. Many dogs recover completely if treatment is initiated quickly and exposure to the mycotoxins is ended.

In severe cases, especially with significant liver damage or neurological symptoms, the prognosis may be more guarded. Long-term damage is possible, and in some cases, the condition can be fatal if action is not taken in time.

Prevention

Prevention of mycotoxicosis in dogs begins with the proper storage and handling of feed and food. Dry food should be stored in airtight containers to prevent moisture and mold growth. Perishable foods should be properly refrigerated and not kept longer than necessary.

Regular inspection of food for signs of mold or spoilage is important. Spoiled or suspicious food should be disposed of immediately. Dogs should not have access to compost, garbage, or other potentially contaminated sources.

The use of high-quality, certified feed can also reduce the risk of mycotoxin contamination. It is important to source feed from trusted manufacturers who perform strict quality controls and testing for mycotoxins.

By implementing these prevention measures, pet owners can significantly reduce the risk of mycotoxicosis in their dogs and protect their health.

Outlook on current research

Mycotoxicosis is poisoning by toxins from molds, not by the fungal infestation itself. Particularly important are toxins such as aflatoxins, ochratoxin A, fumonisins, trichothecenes, and zearalenone. Research and practice have changed significantly in recent years: previously, the focus was mainly on acute poisoning by a single toxin; today, the effects of chronic low-dose exposure and mixed exposure to several mycotoxins are increasingly being investigated. (who.int, efsa.europa.eu)

A central field of research is improved diagnostics. Modern LC-MS/MS methods enable the simultaneous detection of numerous mycotoxins in feed, food, and biological samples. At the same time, researchers are looking for biomarkers in blood, urine, or milk to better record the actual exposure of the individual animal or human. (mdpi.com, frontiersin.org)

A second focus is prevention. Due to climate change, altered storage conditions, and global trade flows, fungal spectra and toxin patterns can shift. Therefore, prediction models, better storage hygiene, as well as binders and biological detoxification processes are being intensively investigated. However, their effectiveness is toxin-dependent and not universally equal. (efsa.europa.eu, frontiersin.org)

Overall, the outlook is good: research is clearly moving toward earlier exposure measurement, more realistic risk assessment, and more targeted prevention instead of merely reacting to poisonings that have already occurred.

Frequently Asked Questions (FAQs)

1. What is mycotoxicosis in dogs?
Mycotoxicosis is poisoning by toxins produced by molds. The toxins are ingested with spoiled food, old leftovers, compost, or damp food. In dogs, tremorgens such as penitrem A and roquefortine C, as well as aflatoxins, are particularly relevant.
2. What are typical sources?
Moldy cheese, old nuts, old bread, moldy dog food, garbage, and especially the compost heap in the garden are classic sources. Dogs usually eat toxic amounts within a short time while roaming free or having access to garbage.
3. What Symptoms occur?
Tremorgenic mycotoxins cause hyperesthesia, muscle tremors, seizures, ataxia, panting, and vomiting within 30 minutes to a few hours. Aflatoxins manifest with a delay through loss of appetite, vomiting, jaundice, and signs of liver failure. Untreated, both forms are potentially life-threatening.
4. How is the diagnosis made?
A medical history involving access to compost or spoiled food is indicative. Specific toxin detection from stomach contents or suspicious material is possible but takes too long for acute therapy. In practice, the presumptive diagnosis is made clinically and treated immediately. In cases of aflatoxicosis, liver enzymes and coagulation are significantly altered.
5. How is acute tremorgenic mycotoxicosis treated?
Rapid decontamination is important: activated charcoal is given, and vomiting can also be induced in conscious patients. Muscle spasms are treated with methocarbamol, and severe seizures with diazepam. Infusion therapy, possibly intravenous lipid emulsion, and monitoring of body temperature supplement the treatment.
6. How is aflatoxin poisoning treated?
Therapy consists of liver protectants such as S-adenosylmethionine and silymarin, vitamin K for coagulation disorders, infusions for circulatory support, and, if necessary, fresh plasma administration. There is no specific antidote; early intensive care is crucial.
7. How quickly must action be taken?
With tremorgens, every minute counts, as untreated seizures can lead to hyperthermia and multiple organ failure within a few hours. Aflatoxins develop their effect more slowly but also require prompt veterinary care as soon as suspicion arises.
8. What is the prognosis for affected dogs?
For tremorgenic mycotoxicosis, the prognosis is good with rapid and consistent therapy; most dogs recover within 24 to 72 hours. For aflatoxin poisoning, the prognosis depends on the extent of liver damage and is guarded to poor in cases of severe liver failure.
9. Can permanent damage occur?
Neurological damage rarely remains after tremorgenic poisoning. After severe aflatoxin poisoning, chronic liver dysfunction or liver cirrhosis can result. Regular monitoring of liver values is sensible after severe cases.
10. How can mycotoxicosis be avoided?
Access to compost heaps, garbage, and spoiled food leftovers must be consistently prevented. Dogs should not roam free on other people's property or in orchards. Feed, especially dry food and treats, should be stored in a dry, airtight manner and checked regularly for mold.

Literature

  • Yang, L., Yang, L., Cai, Y., Luo, Y., Wang, H., Wang, L., Chen, J., Liu, X., Wu, Y., Qin, Y., Wu, Z., & Liu, N. (2023). Natural mycotoxin contamination in dog food: A review on toxicity and detoxification methods. Ecotoxicology and Environmental Safety, 257, Article 114948. https://doi.org/10.1016/j.ecoenv.2023.114948
  • Leung, M. C. K., Díaz-Llano, G., & Smith, T. K. (2006). Mycotoxins in pet food: A review on worldwide prevalence and preventative strategies. Journal of Agricultural and Food Chemistry, 54(26), 9623–9635. https://doi.org/10.1021/jf062363+
  • Boermans, H. J., & Leung, M. C. K. (2007). Mycotoxins and the pet food industry: Toxicological evidence and risk assessment. International Journal of Food Microbiology, 119(1–2), 95–102. https://doi.org/10.1016/j.ijfoodmicro.2007.07.063
  • Barker, A. K., Stahl, C., Ensley, S. M., Jeffery, N. D., & Decus, D. (2013). Tremorgenic mycotoxicosis in dogs. Compendium: Continuing Education for Veterinarians, 35(2), E2.
  • Young, K. L., Villar, D., Carson, T. L., Ierman, P. M., Moore, R. A., & Bottoff, M. R. (2003). Tremorgenic mycotoxin intoxication with penitrem A and roquefortine in two dogs. Journal of the American Veterinary Medical Association, 222(1), 52–53, 35. https://doi.org/10.2460/javma.2003.222.52
  • Braun, V., Kanstinger, A., Hartmann, K., & Dorsch, R. (2024). Mycotoxin poisoning after walnut ingestion in 54 dogs. Tierärztliche Praxis Ausgabe K: Kleintiere/Heimtiere, 52(4), 211–219.
  • Fritz, L., Miklis, A., Bitter, V., & Neiger, R. (2020). Suspected intoxication by tremorgenic mycotoxins in twelve dogs after ingestion of moldy walnuts. Kleintierpraxis, 65(9), 476–481. https://doi.org/10.2377/0023-2076-65-476