Why do older dogs shed big clumps of hair?

Updated November 21, 2016

As dogs get older their skin and coat changes, and sometimes results in the shedding of hair. Some of this shedding is normal and to be expected, but serious hair loss could be the sign of a serious issue, such as a dietary deficiency, infection, stress, allergies or a hormonal imbalance.

Canine Cushing's Disease

In addition to seasonal shedding, some older dogs acquire canine Cushing's disease, which can cause them to shed large clumps of hair. The disease strikes the older dog's pituitary gland. Symptoms include increased appetite and thirst, frequent urination and hair loss in clumps. The hair loss begins around the elbows, flanks and stomach. Veterinarians can diagnose canine Cushing's disease with urinalysis and a blood test, and can prescribe treatment.

Skin and Hair of an Aging Dog

Dogs, like people, get grey hair as they get older. The dog's hair becomes more brittle, breaks easier and therefore can shed more. Skin circulation is not as good as it was in a dog's younger years, which can contributed to poorer hair health. A good grooming routine can improve the skin circulation and can reduce shedding.


Issues with a dog's thyroid glands can cause increased hair loss. Hypothyroidism is a common problem with older dogs and can manifest itself in excessive shedding, a dry coat and hair coming out in clumps. In addition, the condition can make the dog more susceptible to infections and can cause it to gain weight. Medications can improve thyroid function and as a result can reduce hair loss.

Hot Spots

All dogs can acquire "hot spots," but they can be more prevalent as a dog ages. A hot spot is a bald patch of skin where the hair has been shed. It is sometimes caused by a rash or allergy, but most likely, the dog pulled the hair out itself. Sometimes the hot spot can be infected. If your dog has a bald patch, clean the area with hydrogen peroxide and apply an antibiotic ointment, which can be found at pet stores or through a veterinarian. Hot spots can grow if left untreated, with the dog pulling out more hair when biting at the affected skin.

Dietary Needs

As a dog ages, its nutritional needs change. Feeding your dog the same food as when it was younger can contribute to skin problems and can cause it to shed more hair, including in clumps. Foods that are specifically tailored to senior canines can bolster a dog's health and thereby improve its coat. A healthier coat is less likely to come out in clumps.

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About the Author

Jean Rabe has worked in journalism since 1979, serving as a reporter, bureau chief and magazine editor. She has written 27 novels, including "The Finest Creation" and "The Finest Challenge," while her true-crime book, "When the Husband is the Suspect," was written with F. Lee Bailey. Rabe has a Bachelor of Science in journalism from Northern Illinois University.