Alopecia in pets

What It Is

Alopecia is hair loss beyond normal shedding, ranging from a single small bald patch to widespread thinning across the trunk. Vets distinguish self-induced alopecia, where a pet's own licking or scratching wears the coat away, from spontaneous alopecia, where hair falls out without obvious self-trauma. Symmetrical hair loss on both flanks often suggests a hormonal cause, while patchy, irregular loss points more toward infection or parasites. Cats with alopecia frequently have normal-looking skin underneath, since overgrooming is often responsible.

Common Causes

Ringworm, a fungal infection despite its name, causes patchy hair loss with scaling and spreads easily to people and other pets. Mites or fleas can trigger enough itching to cause self-induced loss through chewing. Hypothyroidism and Cushing's disease typically cause symmetrical thinning without itching. Allergic skin disease leads to hair loss indirectly through scratching. Some breeds carry inherited pattern baldness in predictable areas, and stress or an underlying painful condition can trigger compulsive overgrooming in cats.

When It Is an Emergency

Alopecia on its own is almost never an emergency. It becomes more urgent alongside sudden weight loss, lethargy, increased thirst, or a rapidly spreading area of hair loss with redness and discharge, any of which suggest a more serious internal process. Ringworm, while not urgent, should be addressed promptly given how easily it spreads through a household.

What the Vet Will Do

A careful look at the pattern and location of hair loss guides the workup. Skin scrapes check for mites, and a fungal culture or specialized light examination can identify ringworm. If a hormonal cause is suspected based on symmetry, bloodwork will check thyroid and adrenal function. In less clear cases, a skin biopsy can identify rarer causes that scrapes and bloodwork miss.

Home Care and Prevention

Consistent flea and parasite prevention removes one common trigger for self-induced hair loss. If ringworm is suspected, isolating the affected pet and washing hands after contact limits spread while awaiting results. Addressing any underlying allergy or hormonal disease according to the vet's plan is the only reliable way to get hair to regrow. Gentle grooming products help avoid adding further irritation to compromised skin.