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Fungal Culture in Dogs

Learn how and when to do a fungal culture in dogs.

A fungal culture is an easy lab test to help diagnose skin problems in dogs. If it's positive, it indicates the presence of dermatophytosis, which is also called ringworm. The two most common types of fungi in dogs are Microsporum canis and Trichophyton spp.

How Is a Fungal Culture Performed?

When a veterinarian wants to do a fungal culture, they first collect a sample of hairs in the area of skin the doctor is concerned about. They place the hairs on a Petrie dish or in a small jar containing special agar called DTM (dermatophyte test medium).

Once the culture is set up, the dish or jar should go in a dark place like a closet or cupboard, and every day, someone should check to see if there is growth, which shows up as fuzzy and white or light gray.

If whatever grows is another color, it is probably contamination.

Fungal growth can show up as quickly as 5 days, but the culture shouldn't be deemed negative until 14 days have passed.

Once fungus grows on the Petrie dish, the veterinarian can take a tiny sample of the fuzz and place it on a microscope slide with a drop of blue dye. Then, the doctor can confirm the presence of dermatophytes.

Most of the time, a fungal culture can be performed in a regular veterinary clinic but sometimes it is sent to a laboratory. Alternatively, come clinics perform the initial test in-clinic and then send a sample of any growth that comes up to the lab for final identification.

A fungal culture is an easy, fairly cheap, non-invasive test that can help diagnose fungal skin conditions in dogs.

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