# Hair Loss in Dogs With Cushing's or Addison's Disease Hair loss in dogs with Cushing's disease happens because chronically high cortisol damages the hair follicles and suppresses normal hair growth. Addison's disease, the opposite problem, causes low cortisol and often low aldosterone, and it can also leave a dog with a thin or dull coat. The two conditions look alike in some ways and very different in others, so testing matters. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Cushing's disease (hyperadrenocorticism) is a common endocrine disease in adult and older dogs, and it usually comes from a pituitary tumor (85% to 90% of cases) or, less often, an adrenal tumor (10% to 15%) [1]. - The classic Cushing's coat change is a dull, dry, thinning coat that often spares the head and legs, plus a pot belly, panting, and increased drinking and urination. - Addison's disease (hypoadrenocorticism) is far less common and often shows up as vague waxing and waning illness, weight loss, vomiting, and weakness, sometimes with a poor coat. - Hair loss alone rarely points to an adrenal disorder. Your veterinarian needs blood work, and often an ACTH stimulation test, to tell these conditions apart. - Most endocrine hair loss improves only after the underlying hormone problem is controlled, and regrowth can take months. ## What Cushing's Disease and Addison's Disease Actually Are Your dog has two adrenal glands, one sitting on top of each kidney. They make cortisol, which helps the body handle stress and controls many metabolic jobs, and aldosterone, which manages sodium and potassium balance. In Cushing's disease, also called hyperadrenocorticism, the body is flooded with cortisol for a long time [1]. The most common cause is a tumor in the pituitary gland at the base of the brain. That tumor makes a hormone that pushes the adrenal glands to overgrow and overproduce cortisol [1]. Less often, a tumor in an adrenal gland itself pumps out cortisol directly [1]. Long-term use of corticosteroid drugs, such as prednisone for allergies or immune disease, can also create the same picture [1]. In Addison's disease, also called hypoadrenocorticism, the adrenal glands fail to make enough cortisol, and often not enough aldosterone either. This is the mirror image of Cushing's. It tends to be less common and can be harder to spot because the signs come and go. For a deeper comparison of these two adrenal conditions, see [Canine Adrenal Gland Disease: Hyperadrenocorticism and Hypoadrenocorticism](/knowledge/veterinary-medicine/clinical-methods/canine-adrenal-gland-disease-hyperadrenocorticism-hypoadrenocorticism). ## Signs Owners Notice, Including Hair Loss in Dogs With Cushing's Disease ### Cushing's dog hair loss and skin changes Hair loss is one of the most visible signs of Cushing's disease. The coat becomes thin, dry, and dull, and hair falls out in a fairly symmetric pattern. Many dogs lose coat over the trunk and flanks while keeping hair on the head and legs. The skin itself often thins, feels papery, and may darken or become prone to infections. Other common signs include a pot-bellied appearance, heavy panting, increased appetite, and drinking and urinating far more than usual. Some dogs become restless, anxious, or irritable. If behavior changes are part of your dog's picture, [Cushing Disease Dog Behavior Problems](/knowledge/veterinary-medicine/behavior/cushing-disease-dog-behavior-problems) covers that side of the disease. ### Addison's disease dog hair loss and other clues Hair loss in dogs with Addison's disease is less dramatic and less predictable than in Cushing's. Some dogs develop a thin, poor coat, and some show no coat change at all. The bigger clues are systemic. Dogs may vomit, have diarrhea, lose weight, act weak or depressed, and have episodes that seem to improve and then return. Addison's disease often strikes younger dogs. In one study of 141 cases, dogs with the classic form (low sodium and/or high potassium) were diagnosed at a median age of 5.1 years, while dogs without those electrolyte changes were older, at a median age of 8.3 years [2]. A crisis can develop suddenly, with severe weakness or collapse, and that is a medical emergency. ## Causes and Risk Factors Cushing's disease is common in adult and aged dogs [1]. Pituitary tumors account for the large majority of spontaneous cases, and adrenal tumors account for the rest [1]. Certain breeds, including small terriers, poodles, dachshunds, and boxers, are overrepresented in general veterinary practice, though any breed can be affected. Iatrogenic Cushing's, caused by steroid medication, can happen in any dog receiving long-term corticosteroids [1]. Addison's disease has no single known trigger. It is thought to involve immune destruction of the adrenal tissue in many dogs, and it can also be caused by medication. In the same study, 16 of 141 dogs had iatrogenic hypoadrenocorticism, meaning their Addison's disease was caused by treatment for Cushing's disease [2]. That is a reminder that treating one adrenal problem too aggressively can create the opposite one. Rarely, the problem starts higher up in the hormonal chain. One report described a dog with central hypoadrenocorticism, where the pituitary did not signal the adrenal glands properly, and the dog was stabilized long term with prednisolone alone [3]. Hair loss itself has many causes beyond the adrenal glands, including hormonal, immune, genetic, infectious, allergic, parasitic, and behavioral problems [4]. Endocrine disease is one category among many, which is why a veterinarian has to sort out the cause before treating. ## How Veterinarians Diagnose the Cause of Hair Loss Your veterinarian starts with history and a physical exam, then moves to laboratory testing. The goal is to confirm or rule out an adrenal disorder and to exclude other causes of hair loss. | Feature | Cushing's Disease | Addison's Disease | |---|---|---| | Cortisol level | Chronically too high [1] | Too low | | Most common cause | Pituitary tumor (85% to 90%) [1] | Adrenal failure, often immune-related | | Typical age at diagnosis | Adult to aged dogs [1] | Median about 5 years for the classic form [2] | | Signature coat sign | Symmetric thinning over the trunk, dry dull coat | Thin or poor coat, sometimes no coat change | | Signature body signs | Pot belly, panting, heavy drinking and urination | Vomiting, weakness, weight loss, waxing and waning illness | | Key screening clue | High cortisol on testing | Electrolyte changes (low sodium, high potassium) in many dogs | Screening tests for Cushing's include blood work, urine testing, and an ACTH stimulation test or a low-dose dexamethasone suppression test. Your veterinarian chooses based on your dog's signs and other health issues. Imaging such as ultrasound can help identify an adrenal tumor. For Addison's, the ACTH stimulation test is the standard confirmatory test. Baseline blood work often shows characteristic electrolyte abnormalities, though not every dog has them, as the age data above shows [2]. If the diagnosis is unclear, referral to an internal medicine specialist may help. Because hair loss has so many possible causes, your veterinarian may also check thyroid function, skin scrapings, and skin cytology. A skin biopsy is occasionally needed when the pattern is unusual. One case report described a rare form of alopecia called follicular mucinosis in a golden retriever, with hair loss favoring the face, neck, and limbs, confirmed by biopsy [5]. That is uncommon, but it shows why not every bald dog has an adrenal problem. ## Treatment Options and What They Do to the Coat ### Treating Cushing's disease Treatment depends on the cause. Pituitary-dependent Cushing's is usually managed with medication that reduces cortisol production. Adrenal tumors are often removed surgically when possible. If a steroid medication caused the problem, your veterinarian will taper it carefully, because stopping suddenly can be dangerous. Your veterinarian calculates every dose from your dog's weight, test results, and overall health. Doses are not something to adjust at home. Over-treatment is a real risk, and it can push a dog into Addison's disease, which is exactly what happened in 16 of the 141 dogs in that case series [2]. ### Treating Addison's disease Addison's disease is managed with hormone replacement. Many dogs receive a mineralocorticoid injection given on a schedule, plus daily glucocorticoid pills. Some dogs do well on prednisolone alone, as in the central hypoadrenocorticism case [3]. Your veterinarian sets the exact regimen and adjusts it based on electrolyte checks and how your dog feels. For a full look at diagnosis and long-term care, see [Addison's Disease in Dogs: Clinical Diagnosis, Treatment & Management](/knowledge/veterinary-medicine/endocrine-diseases/addisons-disease-in-dogs). If your dog is in or near a crisis, [Addison's Disease in Dogs: Hypoadrenocorticism Crisis Electrolyte Balance](/knowledge/veterinary-medicine/internal-medicine/addisons-disease-in-dogs-hypoadrenocorticism-crisis-electrolyte-balance) explains what happens and why it is urgent. ### What happens to the hair Hair regrowth follows hormone control, not the other way around. Once cortisol levels are back in a healthier range, or replacement hormones are steady, the follicles can start producing normal hair again. This takes time. Many dogs need several months before the coat looks noticeably better, and some never fully return to their original coat. Veterinary management of alopecia centers on finding and correcting the underlying disorder [4]. Coat supplements and shampoos may support skin health, but they do not fix an adrenal problem. One case report described coat improvement in a dog with suspected alopecia X after combined nutrient supplementation, but that condition is different from Cushing's and Addison's, and the report involved a single dog [6]. ## Recovery, Outlook, and Long-Term Management With treatment, most dogs with Cushing's disease improve in energy, appetite, drinking, and urination within weeks to a few months. The coat is usually the slowest thing to recover. Expect a shabby look for a while even when your dog feels much better. Addison's disease has a good long-term outlook with consistent treatment. In the 141-dog study, survival was tracked over the period when a long-acting mineralocorticoid injection became widely used, and glucocorticoid side effects were also recorded [2]. Your veterinarian will monitor electrolytes and adjust treatment over time. Both conditions need lifelong veterinary care. Plan on regular blood work, dose adjustments, and check-ins. Keep a simple log of your dog's drinking, appetite, energy, and any vomiting or weakness. That record helps your veterinarian fine-tune treatment. ## Prevention You cannot prevent most cases of Cushing's or Addison's disease, because they usually stem from tumors or immune-related adrenal damage. What you can do is reduce the risk from medication. If your dog needs long-term corticosteroids, ask your veterinarian about the lowest effective dose and regular monitoring, since prolonged steroid use can cause Cushing's signs [1]. Keep routine wellness visits, especially as your dog ages. Early detection of an adrenal disorder makes management easier and lowers the chance of a crisis. If you notice coat changes along with drinking, appetite, or energy changes, bring it up at your next visit instead of waiting. ## Limitations and When to Contact a Veterinarian No article can diagnose your dog. Hair loss has many causes, and adrenal disease is only one of them [7]. Your veterinarian needs to examine your dog and run tests to know what is going on. Contact your veterinarian the same day if your dog has sudden heavy drinking and urination, a rapidly expanding belly, new weakness, or a coat that is falling out quickly. Go to an emergency clinic now if your dog collapses, cannot stand, has severe vomiting or diarrhea, seems confused, or has a slow or irregular heartbeat. An Addisonian crisis can be fatal without immediate treatment. Call poison control if you suspect your dog ate a medication or toxin. The ASPCA Animal Poison Control Center is available at (888) 426-4435, and the Pet Poison Helpline is available at (855) 764-7661. A consultation fee may apply. Schedule a routine visit if you notice gradual coat thinning, patchy hair loss, itching, or a change in skin color or texture. Itching should be investigated first when it is present [7]. ## Frequently Asked Questions ### Does Cushing's disease always cause hair loss in dogs? No, but it is one of the most common and most visible signs. Some dogs show mainly drinking, urination, appetite, and belly changes, with only mild coat thinning. If your dog has several of these signs together, testing is worthwhile. ### Can Addison's disease cause hair loss in dogs? It can, but coat changes are usually milder and less consistent than in Cushing's. Many dogs with Addison's disease have normal-looking coats, and the diagnosis is made from blood work and ACTH stimulation testing. The systemic signs, such as vomiting and weakness, are often the main clue. ### Will my dog's hair grow back after treatment starts? Usually it improves, but regrowth is slow and depends on how long the hormone problem went on. Some dogs regain a full coat, and some stay thinner than before. Your veterinarian can track progress with exams and lab work over the first several months. ### How long does it take to see coat improvement? It often takes months, not weeks. Energy and appetite usually improve first, and the coat follows later. If the coat is not improving after the hormone problem is well controlled, ask your veterinarian to look for other skin or hormonal causes. ### Is hair loss in dogs with Cushing's disease painful? The hair loss itself is typically not painful. The skin underneath can become thin, dry, and prone to infection, which may cause discomfort or itching. If your dog seems uncomfortable, that needs its own evaluation, because itching should be investigated first [7]. ## Related Articles - [Cushings Disease in Dogs: Pituitary vs Adrenal Hyperadrenocorticism Guide](/knowledge/veterinary-medicine/internal-medicine/cushings-disease-in-dogs-pituitary-vs-adrenal-hyperadrenocorticism-guide) - [Cushing Disease Dog Behavior Problems](/knowledge/veterinary-medicine/behavior/cushing-disease-dog-behavior-problems) - [Addisons Disease in Dogs: Hypoadrenocorticism Crisis Electrolyte Balance](/knowledge/veterinary-medicine/internal-medicine/addisons-disease-in-dogs-hypoadrenocorticism-crisis-electrolyte-balance) - [Addison's Disease in Dogs: Clinical Diagnosis, Treatment & Management](/knowledge/veterinary-medicine/endocrine-diseases/addisons-disease-in-dogs) - [Canine Adrenal Gland Disease: Hyperadrenocorticism and Hypoadrenocorticism](/knowledge/veterinary-medicine/clinical-methods/canine-adrenal-gland-disease-hyperadrenocorticism-hypoadrenocorticism) - [Why Is My Dog Losing Hair?](/knowledge/veterinary-medicine/parasitic-diseases/why-is-my-dog-losing-hair) ## References 1. [Disorders of the Adrenal Glands in Dogs - Dog Owners](https://www.merckvetmanual.com/dog-owners/hormonal-disorders-of-dogs/disorders-of-the-adrenal-glands-in-dogs). Merck Veterinary Manual. 2. [Clinical characteristics, treatment, and outcomes of hypoadrenocorticism in dogs](https://pubmed.ncbi.nlm.nih.gov/40237295/). The Journal of small animal practice, 2025. 3. [A dog with suspected hypothalamic hypoadrenocorticism classified by corticotropin-releasing hormone (CRH) testing](https://pubmed.ncbi.nlm.nih.gov/42604803/). The Journal of veterinary medical science, 2026. 4. [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. 5. [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. 6. [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. 7. [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. ## 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)