Symptoms of Dermatophytosis in Dogs

Dog's tend to develop ringworm on their face, paws and tail first.
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Skin infections aren't fun for you or your pet. Dermatophytosis is a contagious disorder caused by various parasitic fungal species. It's also known as ringworm, because it creates distinct circular lesions on the skin. Infections spread and escalate quickly, so dog owners should check for symptoms regularly during grooming sessions.

Balding Skin

An active infestation of dermatophytes creates patches of inflamed skin, which damages the follicles and makes fur fall out. The fungal infection spreads outward in a ring from a small spot, so the patches are often round. Hair may grow in the center of a lesion once the ring has spread out enough. It takes one to two weeks for dogs to develop hair loss after exposure to ringworm, according to The Drake Center for Veterinary Care. Ringworm can spread quickly across your pet's entire body, so bald patches may emerge anywhere form his face to rear.

Relentless Scratching

While most cases of ringworm aren't uncomfortable for your pet, some lesions can become itchy and painful, according to VCA Animal Hospitals. This can make the infection much worse. Your dog's gleeful scratching may spread the fungus to his nails, and eventually to the rest of his body, even to you. Ringworm lesions can bleed and develop scabs, which makes them even more itchy. Dermatophytes are opportunistic parasites that often develop as secondary infections on animals who have existing skin problems, so the minor skin irritation may compound with other issues.

Breaking Nails

The fungi responsible for ringworm survive consume a substance called keratin, which is a building block for hair and nails. Dermatophytes can infect the beds of your dog's claws, causing a condition called onychomycosis. The fungus making the hard claws brittle, weak and uneven. You also may notice brown or yellow discoloration of the nails, as well as balding patches on paw itself.

Hiding in Plain Sight

While ringworm is a common cause of skin issues in dogs and humans alike, it does not always successfully infect its host. While this may seem like good news for the dog, it can be frustrating for the other residents of the home. Dogs and cats can harbor active dermatophytes on their skin and fur without becoming infected or showing any symptoms. They can transfer the disease to their owners and fellow pets without showing any clinical signs. Fungal cultures in a laboratory are the only way to identify ringworm carrier animals.


Ringworm is rarely serious, but it usually warrants a trip to the vet's office. There are several prescription treatments to fight fungal infections, including topical ointments and tablets. Your vet will recommend the one he believes suits the severity of your pet's infection. While the bald patches and other symptoms may disappear quickly, your pet's infection will remain contagious for at least three weeks after treatment begins, according to Quarry Hill Park Animal Hospital.