# Why Is Your Senior Dog Losing Hair on the Tail and Ears? Senior dog losing hair is common, and the tail, ears, and flanks are the classic spots owners notice first. Sometimes it is just the normal thinning that comes with age, but often it points to a hormone problem, parasites, or skin disease that a veterinarian can diagnose and treat. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Symmetric hair loss on the tail, rear, and flanks without itching or redness is a common pattern in older dogs and often points to an endocrine (hormone) cause such as an underactive thyroid or Cushing's syndrome. - Hair loss on the ears is frequently linked to scratching, head shaking, or ear infections, so check the ear canal for redness, discharge, or odor. - Alopecia is a sign, not a diagnosis. The underlying cause must be identified before the condition can be treated successfully [1]. - If your dog is also itchy, the itching should be investigated first, because self-trauma can cause the hair loss [1]. - Any rapid, patchy, crusty, or painful hair loss, or hair loss with weight loss, vomiting, or lethargy, needs a veterinary visit soon. ## What Senior Dog Hair Loss on the Tail and Ears Looks Like Hair loss, or alopecia, means a partial or complete lack of hair in areas where hair is normally present [1]. In older dogs, owners often describe a few distinct patterns. On the tail, you may see the plume thin out, or a "rat tail" where the hair thins along the length of the tail and over the rear end. On the ears, the hair can thin on the ear flaps, or you may notice bald patches around the base of the ear where your dog scratches. The flanks, belly, and neck often thin at the same time. ### Normal aging changes Some coat thinning in senior dogs is simply part of getting older. Hair follicles become less active over time, and the coat may look duller, thinner, and slower to regrow. This normal change tends to be gradual, symmetric, and not itchy or inflamed. The skin underneath looks normal, not red, crusty, or greasy. ### When it is not just aging The pattern matters. Hair loss that is symmetric on both sides of the body, that spares the head and legs, and that comes with skin darkening or a dull coat is more suspicious for a hormone problem. Hair loss that is patchy, crusty, or itchy points more toward infection, parasites, or allergy [1]. ## Main Causes of Hair Loss on the Tail and Ears Acquired hair loss means your dog was born with a normal coat and lost hair later [1]. Most senior dog coat loss falls into this group. Here are the causes veterinarians consider most often. | Cause | Typical clues | How urgent | |---|---|---| | Normal aging | Gradual, symmetric thinning, no itching, normal skin | Routine visit | | Hypothyroidism | Symmetric hair loss on tail, rear, flanks, dull coat, weight gain, low energy | Routine to soon | | Cushing's syndrome | Potbelly, thinning coat, skin darkening, increased drinking and urination | Soon | | Alopecia X | Non-inflammatory hair loss in double-coated breeds, no other signs | Routine | | Parasites (mites, fleas) | Itching, scaling, crusts, patchy loss | Soon | | Skin infection (bacterial, fungal) | Redness, odor, pustules, crusts | Soon | | Allergy | Itching, redness, recurrent ear problems | Soon | | Rare follicular disease | Hair loss favoring face, neck, limbs | Routine to soon | ### Hormone problems: thyroid and Cushing's An underactive thyroid is a leading suspect when a senior dog loses hair symmetrically on the tail, rear, and flanks. Hypothyroidism has been documented in older dogs and can cause signs beyond the coat, including episodes of collapse in some breeds [2]. Treatment with thyroid hormone replacement improved or resolved those signs [2]. Cushing's syndrome (too much cortisol) causes a thin coat, a potbelly, and skin changes. Your veterinarian can test for both conditions with blood work. ### Alopecia X Alopecia X is a non-inflammatory hair loss seen most often in dogs with double coats and dense undercoats [3]. The cause is not known, and it can be challenging to manage [3]. In one reported case, an 8-year-old Chihuahua with significant hair loss improved markedly after 66 days of nutritional supplementation, with near-full coat coverage on the back, sides, and abdomen [3]. That is a single case report, so it does not prove the supplement caused the regrowth. Your veterinarian will help you decide whether any supplement is worth trying. ### Parasites and skin infections Mites, fleas, and fungal infections can all cause hair loss, especially when the dog is itchy. If your dog has hair loss and is scratching the area excessively, the itching should be investigated first [1]. That is because scratching itself damages hair and skin, and treating the itch often reveals the true cause. ### Allergy and ear disease Allergies frequently show up as recurrent ear infections and hair loss around the ears. If your dog shakes its head, scratches its ears, or has discharge or odor, the ear canal is likely involved. You can read more about that pattern in [Dog Ear Infection with Hair Loss: What's Going On?](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/dog-ear-infection-hair-loss). ### Rare causes Some uncommon conditions cause alopecia in specific patterns. Follicular mucinosis is a rare form of alopecia in dogs that favors the face, neck, and limbs [4]. It has been successfully treated in at least one reported case [4]. These conditions are diagnosed by skin biopsy, not by appearance alone. ## Red Flags That Mean Emergency or Same-Day Care Most hair loss is not an emergency. These signs are different. - Sudden, widespread hair loss with open sores, bleeding, or severe pain. - Facial swelling, hives, or difficulty breathing (possible severe allergic reaction). - Collapse, fainting, or episodes of losing consciousness. In older Boxers, this has been linked to hypothyroidism, and treatment improved or resolved the episodes [2]. - Non-healing wounds, deep skin infections, or a foul smell with fever. - Extreme lethargy, vomiting, or not eating, especially with rapid coat loss. If you see any of these, call your veterinarian right away or go to an emergency clinic. ## Safe Things You Can Do at Home While You Wait You cannot diagnose hormone disease at home, but you can protect your dog's skin and gather useful information. - Take dated photos of the tail, ears, flanks, and belly every two weeks. Patterns over time help your veterinarian. - Note changes in drinking, urination, appetite, weight, and energy. These clues point toward or away from hormone causes. - Do not start or stop any medication, supplement, or shampoo without veterinary guidance. Some products can interfere with testing. - Use only flea and mite products prescribed or recommended for your dog's weight and health status. - Keep the skin clean and dry. Gently wipe discharge from the ear flap, but do not push anything into the ear canal. - Prevent scratching with an Elizabethan collar or a soft cone if your dog is damaging the skin. - Do not use human hair loss products. Treatments approved for people, such as minoxidil and finasteride, are not approved for dogs, and veterinary management depends on finding and correcting the underlying disorder [5]. If your dog's hair loss is patchy instead of symmetric, see [Why Is My Dog Losing Hair in Patches? Common Causes and Next Steps](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/dog-hair-loss-patches-causes-next-steps) for more on that pattern. ## What Your Veterinarian Will Check and Test Your veterinarian will start with a full history and physical exam. Expect questions about diet, flea prevention, itching, and any changes in thirst, urination, or energy. ### Skin and coat examination The veterinarian will map where the hair is missing, check for symmetry, and look at the skin for redness, scaling, crusts, and darkening. A Wood's lamp, skin scraping, or tape preparation may be used to look for mites and infections. ### Blood and urine testing If hormone disease is suspected, your veterinarian will recommend blood work. Thyroid testing and a cortisol test (often called a low-dose dexamethasone suppression test) are common. A urinalysis and a general health panel help rule out other problems. ### Ear examination If the ears are involved, the veterinarian will look inside the ear canal with an otoscope and may take a sample of discharge to check for bacteria, yeast, or mites. ### Skin biopsy When the diagnosis is still unclear, a small skin sample can identify rare conditions such as follicular mucinosis [4]. This is usually done after simpler tests. Treatment depends on the diagnosis. Thyroid disease is managed with thyroid hormone replacement, and the dose is calculated by your veterinarian based on your dog's weight and test results [2]. Cushing's syndrome, infections, and parasites each have their own specific treatments. No single shampoo or supplement treats all causes. ## Prevention and Monitoring for Senior Dogs You cannot prevent every cause of coat loss, but you can catch problems earlier. - Schedule a wellness exam at least once or twice a year for senior dogs. Ask your veterinarian to check the coat and skin at every visit. - Keep parasite prevention current year-round. - Feed a complete and balanced diet. If you want to try a coat supplement, ask your veterinarian first. In the reported alopecia X case, improvement was seen after 66 days of supplementation, but that was one dog and not proof of cause and effect [3]. - Track water intake and urination. A sudden increase can be an early sign of hormone disease. - Treat ear infections promptly. Recurrent ear problems often signal allergy or another underlying issue. - Weigh your dog monthly. Unexplained weight gain or loss is worth a call. If the hair loss is mainly on the tail, see [Dog Hair Loss on Tail: Causes and Treatment](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/dog-hair-loss-tail). If it is mainly on the ears, see [Dog Hair Loss on Ears: Causes and Treatment Options](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/dog-hair-loss-on-ears). For a broader overview, see [Why Is My Dog Losing Hair?](/knowledge/veterinary-medicine/parasitic-diseases/why-is-my-dog-losing-hair). ## Limitations and When to Contact a Veterinarian This article cannot tell you what is causing your dog's hair loss. Only a veterinarian who examines your dog and runs tests can do that. Individual cases need a veterinarian. Call for an emergency visit now if your dog is struggling to breathe, has collapsed, has sudden severe skin wounds, or has facial swelling. Call the same day if you see rapid hair loss, open sores, a bad smell from the skin or ears, severe itching that keeps your dog awake, or a head tilt with ear pain. Schedule a routine visit within a week or two if the hair loss is gradual, symmetric, and your dog otherwise seems well. Do not wait months. Early diagnosis of thyroid disease or Cushing's syndrome makes management easier. ## Frequently Asked Questions ### Is it normal for a senior dog to lose hair on the tail? Some gradual thinning on the tail can be a normal part of aging, especially if the skin looks healthy and your dog is not itchy. Symmetric hair loss on the tail and rear, with a dull coat or weight gain, is more suspicious for a hormone problem such as hypothyroidism. A veterinarian can tell the difference with an exam and blood work. ### Why are my older dog's ears losing hair? Ear hair loss is often caused by scratching, head shaking, or an ear infection. Check the ear canal for redness, discharge, or odor. If the ear looks normal and the hair loss is on both ear flaps, a systemic cause such as a hormone imbalance or allergy may be involved. ### Can thyroid problems cause hair loss in dogs? Yes. Hypothyroidism is a well-recognized cause of symmetric coat loss in older dogs. It can also cause weight gain, low energy, and in some breeds, episodes of collapse. Treatment with thyroid hormone replacement has resolved or improved these signs in reported cases [2]. ### Will the hair grow back after treatment? Often it does, but it takes time. Hair regrowth follows the hair growth cycle, so you may wait weeks to months to see a full coat. In one reported alopecia X case, coat coverage improved markedly after 66 days of supplementation [3]. Your veterinarian will set expectations based on the diagnosis. ### Should I try a supplement for my dog's coat? Ask your veterinarian before starting any supplement. Some nutrients support skin and coat health, and one case report described improvement in a dog with suspected alopecia X [3]. However, a single case does not prove a supplement works, and supplements do not treat infections, parasites, or hormone disease. ## Related Articles - [Why Is My Dog Losing Hair?](/knowledge/veterinary-medicine/parasitic-diseases/why-is-my-dog-losing-hair) - [Dog Hair Loss on Tail: Causes and Treatment](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/dog-hair-loss-tail) - [Dog Hair Loss on Ears: Causes and Treatment Options](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/dog-hair-loss-on-ears) - [Dog Ear Infection with Hair Loss: What's Going On?](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/dog-ear-infection-hair-loss) - [Why Is My Dog Losing Hair in Patches? Common Causes and Next Steps](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/dog-hair-loss-patches-causes-next-steps) - [Dog Losing Lots of Hair: Is It Normal Shedding or a Problem?](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/dog-losing-lots-of-hair) - [Hair Loss in Dogs and Thyroid Disease: What the Link Means](/knowledge/veterinary-medicine/endocrine-diseases/dog-hair-loss-thyroid) - [Hair Loss in Dogs With Cushing's or Addison's Disease](/knowledge/veterinary-medicine/endocrine-diseases/dog-hair-loss-cushings-addisons) - [Dog Hair Loss: Causes, Home Care, and Diet Fixes](/knowledge/veterinary-medicine/skin-allergy-and-ear-care/dog-hair-loss-home-remedies) ## References 1. [Hair Loss (Alopecia) in Dogs - Dog Owners](https://www.merckvetmanual.com/dog-owners/skin-disorders-of-dogs/hair-loss-alopecia-in-dogs). Merck Veterinary Manual. 2. [Transient loss of consciousness in boxer dogs with hypothyroidism: 3 cases (2015-2018)](https://pubmed.ncbi.nlm.nih.gov/41398279/). BMC veterinary research, 2025. 3. [Improvement in coat condition observed in dogs with suspected alopecia X through combined supplementation with nutrients for the coat and skin: A case report](https://pubmed.ncbi.nlm.nih.gov/42376514/). Open veterinary journal, 2025. 4. [Successful Treatment of Idiopathic Follicular Mucinosis in a Golden Retriever: Clinical, Dermoscopic and Histopathological Findings](https://pubmed.ncbi.nlm.nih.gov/41906864/). Veterinary dermatology, 2026. 5. [Alopecia management from a comparative perspective: pharmacological and pharmaceutical insights in humans, dogs, and cats](https://pubmed.ncbi.nlm.nih.gov/42713429/). Frontiers in veterinary science, 2026. ## Further Reading - [Merck Veterinary Manual: Dog Owners](https://www.merckvetmanual.com/dog-owners) - [Cornell Richard P. Riney Canine Health Center: Canine Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-information) - [American Veterinary Medical Association: Pet Care](https://www.avma.org/resources-tools/pet-owners/petcare)