A thinner, grayer coat can come with age, but bald patches or hair loss on both sides of the body are not. See the common causes, from hypothyroidism and Cushing's to mites, and when to see a vet.
A slightly thinner or grayer coat can come with age, but bald patches, hair loss on both sides of the body, or thinning with itching, redness, a pot belly or extra thirst needs a vet visit (AKC, Merck). Common causes in older dogs are hormone diseases like hypothyroidism and Cushing's disease, skin infections, mites, allergies and pressure sores. Vets usually start with a skin exam, skin scrapings and blood work.
Quick take: Note where the hair is missing, whether your dog itches, and whether they drink more than before. Our free water intake calculator shows if drinking is high. Photograph bald areas weekly to track spread.
| What you see | Possible causes | Other clues |
|---|---|---|
| Thinning on both sides, little itch | Hypothyroidism or Cushing's (Merck) | Weight gain, low energy (thyroid); thirst, pot belly, panting (Cushing's) |
| Itchy, red, scabby or smelly skin | Allergies, fleas, bacterial or yeast infection (Merck) | Licking, chewing, scratching |
| Round, scaly or crusty patches | Ringworm or Demodex mites (Merck, AKC) | Confirmed by culture or skin scraping |
| Bald, thick skin on elbows or hips | Pressure sores (AKC) | Big dogs lying on hard floors |
| Bald strip under a collar | Friction from a poorly fitted collar (Merck) | Rubbing in one spot |
A gray muzzle and seasonal shedding are usually normal (AKC). See your vet for:
Most common in dogs 4 to 10 years old and in medium to large breeds. Signs include low energy, weight gain without eating more, seeking heat, a dry coat, heavy shedding and hair loss on both sides. Vets test thyroid hormone (T4); treatment is a daily hormone replacement, usually for life, judged after 4 to 8 weeks (Merck). See our hypothyroidism guide.
Affects middle-aged and older dogs; Miniature Poodles, Dachshunds, Boxers, Boston Terriers and Beagles are at higher risk. Signs include more thirst and urination, a bigger appetite, a potbelly, panting, thin skin, bruising and hair loss. Diagnosis takes special blood and urine tests, and medicines such as trilostane lower cortisol (Merck).
Some thinning can come with age (AKC), but bald spots or hair loss on both sides of the body needs a vet check.
Yes. Hair loss and thin skin are listed signs, along with more thirst and urination, a bigger appetite, a potbelly and panting (Merck).
It depends on the cause. With hypothyroidism, vets judge the response after 4 to 8 weeks of treatment (Merck).
Sources: AKC, Merck: hair loss, Merck: thyroid, Merck: Cushing's.
Related guides: Senior dog drinking a lot of water, Skin lumps on senior dogs.
Educational only, not veterinary advice. As an Amazon Associate, SILVERPAW earns from qualifying purchases.
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