Fungal Toxicosis Related To Fusarium Fungus in Dogs

Infestation in crops by fungi in the Fusarium family can lead the development of a mycotoxin in the grain. If this grain is used to prepare your dog’s food it can lead to dermatophytosis and mild to severe gastric distress. Exposure to mycotoxins caused by Fusarium fungi can be difficult to diagnose, but the prognosis is quite good once the contaminated food is removed from the diet.

Fungal toxicosis, or mycotoxicosis, is caused by the ingestion of mycotoxins produced by a fungus in the genus Fusarium. it can lead to dermatophytosis and mild to severe gastric distress.

The most common response to the Fusarium fungus for dogs is a refusal or reluctance to eat the contaminated food and vomiting, but any or all of the following may indicate a Fusarium infection.

• Dermatophytosis (skin condition similar to ringworm)
• Diarrhea
• Excessive drooling
• Irritation to mucous membranes
• Kidney lesions 
• Low blood pressure
• Paronychia (inflammation of nailbed) 
• Refusal or reluctance to eat
• Secondary infections
• Vomiting 

Types

There are at least two varieties of Fusarium fungus that are known to cause a pathogenic response in canines:

• Fusarium sporotrichioides – a strain of fungal plant pathogen in the Fusarium family that infects grain crops and is known to produce Trichothecenes mycotoxins
• Fusarium solani – a soil borne fungus strain in the Fusarium family with a broad range of substrates and habitats

The fungal genus of Fusarium is widely distributed in soil and plants. Most of the species have no discernable effect on us or on our pets. A few species produce mycotoxins called trichothecenes. In many cases animals will refuse the tainted food, and if no alternative is offered they will eat only reluctantly. If ingested the mycotoxins can present as skin lesions that are similar to the lesions found in ringworm and other irritations to the skin and mucous membranes, but it more often causes digestive upsets such as excessive drooling, vomiting, and diarrhea. Deoxynivalenol (DON) is a trichothecene associated with fusarium infections of crops and is subject to regulatory limits by the FDA. Limits of five to ten parts per million (PPM) are imposed on animal feeds and just one part per million on foods for human consumption.

Fusarium infection is challenging to diagnose as the symptoms are somewhat non-specific. The toxic nature of the fungus also reduces immune function, leading to secondary infections. These secondary infections can easily mask the symptoms of the reaction to the mycotoxin which further complicates the development of an accurate diagnosis. The clinical history of the patient can be instrumental in selecting the appropriate tests to determine whether or not mycotoxins are present, and diagnostic tests such as x-rays, urinalysis, and complete blood count may be required. Investigations of possible mycotoxicosis should include a thorough examination of any areas of dermatophytosis that have developed. If contamination of the food is suspected a change to different food should reduce or eliminate the symptoms quickly. This would support the idea that the feed is contaminated but does not by itself prove mycotoxicosis. Your veterinarian may want to inspect and possibly test the food for mycotoxins, however, the mycotoxins are often distributed unevenly throughout the food which makes the collection of useful samples of food very difficult.

The first course of action in any treatment plan involving contamination of food is to stop the exposure to the mycotoxin by removing access to the contaminated feed and replacing it with untainted feed. In many cases, this by itself will be enough to reduce or eliminate the symptoms. When symptoms are severe or when dermatophytosis is present an azole antifungal drug such as itraconazole (ITZ) will likely be prescribed as well. Depending on the severity of the symptoms other supportive measures may be indicated. Fusarium infestations are also known to suppress the immune system and additional treatments may be required to eliminate any secondary viral or bacterial infections that may have developed. Intravenous fluids may be given to replace lost fluids and nutrients from vomiting and diarrhea, and in some cases, your veterinarian may want to keep your pet in the hospital to monitor their blood pressure and body temperature.

In most situations recovery from mycotoxin is fairly rapid once the contaminated food is removed from the diet. During the recovery period 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. In cases where the mycotoxicosis has led to a secondary viral or bacterial infection additional steps may be required to dispel the additional illness. Any antifungal or antibiotic medication prescribed should be given for the full treatment period as instructed by your veterinarian 

As Fusarium is a fungus that infects mainly grains feeding your canine a grain-free food option can also reduce the risk of exposure to mycotoxins.