Why Is My Pet Losing Hair? Endocrine vs. Skin Causes Explained
You are giving your dog their usual belly rub when you notice it: a patch of skin where there used to be fur. Or maybe your cat’s once-luxurious coat is looking thin and dull, and you have been finding more hair on your furniture than seems normal. Hair loss in pets is one of those problems that starts small and slowly becomes impossible to ignore. The good news is that most cases of alopecia, the medical term for hair loss, improve significantly once we figure out what is causing it and address the problem at its source.
The challenge is that hair loss can stem from many different causes: allergies, parasites, skin infections, hormonal imbalances, stress, or nutritional deficiencies. The pattern of hair loss, its location on the body, and whether your pet is itching all provide important clues. At Boca Midtowne Animal Hospital in Boca Raton, Florida, we use digital cytology and comprehensive diagnostics to pinpoint the underlying cause quickly and accurately. As a Fear Free certified practice, we prioritize keeping your pet comfortable throughout the evaluation process. If your pet’s coat is changing, please request an appointment so we can help restore their healthy, comfortable coat.
What Is Alopecia, and How Is It Different from Normal Shedding?
Alopecia simply means partial or complete hair loss. It is not a disease itself but a symptom indicating something else is affecting the skin, hair follicles, or internal systems.
Here is how to tell the difference between normal shedding and abnormal hair loss:
| Normal Shedding | Abnormal Alopecia |
| Even thinning across the body | Bald patches or localized loss |
| Seasonal patterns | Can occur any time of year |
| No skin changes | Redness, scaling, or irritation |
| Hair regrows normally | Hair does not regrow or grows abnormally |
| No excessive scratching | Often accompanied by itching or licking |
The pattern, texture, and accompanying symptoms all guide diagnosis. Our vet services include thorough skin evaluations to distinguish normal shedding from conditions that need treatment.
Can Allergies Cause Hair Loss in Pets?
Allergies are among the most common causes of hair loss and skin discomfort in pets. When the immune system overreacts to environmental or food triggers, inflammation and itching lead to scratching, licking, and eventually bald spots.
Pet allergies can be triggered by:
- Environmental allergens: Pollen, grass, mold (seasonal patterns)
- Dust mites: Year-round symptoms
- Food proteins: Chicken, beef, dairy, wheat
- Flea saliva: Even one bite can trigger intense reactions
General environmental allergies tend to cause more widespread itching and hot spots. In many parts of the US, environmental allergies are “seasonal”- but Florida’s tropical climates mean allergies can happen all year. Long-term allergy management often involves identifying specific triggers through testing, prescription diets for food allergies, and medications that control itching and inflammation. Our team can help develop a plan that keeps your pet comfortable.
Do Parasites and Skin Infections Cause Bald Patches?
External parasites cause hair loss by irritating the skin or damaging hair follicles directly. Mites and other parasites have characteristic patterns:
- Fleas: Flea allergies typically cause hair loss on lower back, tail base, and inner thighs with intense itching and visible flea dirt.
- Demodex mites: Patchy loss affecting face and paws with mild itching and red skin
- Sarcoptes mites (scabies): Ears, elbows, and abdomen with severe itching and crusting (can spread to humans)
Puppies and immunocompromised pets are more susceptible to parasitic skin conditions like mange mites. South Florida, our warm, humid climate means parasites are present year-round, making year-round parasite prevention essential.
Bacterial and yeast infections can also cause hair loss when intense itchiness leads to excessive scratching. Ringworm, a fungal disease, causes circular bald spots with scaly edges- and can spread to humans. Diagnosing these conditions requires skin scrapings, cytology, or fungal cultures. Our in-house digital cytology allows us to identify many causes during the same appointment, so treatment can begin right away.
How Do Hormonal Imbalances Affect Coat Health?
Internal hormone imbalances frequently cause gradual, symmetrical hair loss that typically is not itchy or painful. These changes may go unnoticed initially but can dramatically shift coat texture and color over time.
Thyroid and Adrenal Disorders
Hypothyroidism occurs when the thyroid gland does not produce enough hormones. It commonly affects dogs and causes:
- Weight gain and lethargy
- Cold intolerance
- Symmetrical hair loss on the trunk and tail (“”rat tail”” appearance)
- Dull, brittle coat
In cats, hyperthyroidism (the opposite problem, too much thyroid hormone) causes a patchy, unkempt coat along with weight loss despite increased appetite.
Cushing’s disease results from excess cortisol production and causes:
- Pot-bellied appearance
- Fragile skin
- Increased thirst and urination
- Hair loss along the sides of the body
It’s most common in dogs, but cats can also develop Cushing’s disease with similar symptoms.
Sex Hormone Imbalances
Testicular tumors in intact male dogs can produce excess estrogen, leading to symmetrical hair loss on the flanks, chest, and genital area. Intact females may develop similar issues related to ovarian cysts or tumors. Spaying or neutering often resolves hormone-related alopecia in these cases.
Watch for Human Hormone Product Exposure
An often-overlooked risk: if you use topical hormone creams or gels (estrogen, testosterone, or other hormone replacement therapies), your pet can absorb these hormones through skin-to-skin contact or licking. This can cause hair loss and other symptoms. Apply topical hormones to areas pets cannot reach, wash hands thoroughly, and cover application sites with clothing.
Why Routine Blood Work Matters
Routine blood work can reveal hormone imbalances long before symptoms become obvious, making regular testing crucial for early detection. Our veterinary wellness care visits include bloodwork screening that helps catch these conditions early.
Are Some Breeds Prone to Hair Loss?
Some breeds are genetically predisposed to certain forms of alopecia that cannot be cured but can be managed:
- Color dilution alopecia: Affects dogs with diluted coat colors (blue, fawn, silver). Common in Dobermans, Weimaraners, and Italian Greyhounds.
- Flank alopecia: Seasonal bald patches on the sides that typically regrow. Common in Boxers, Bulldogs, and Airedales.
- Pattern baldness: Gradual thinning in specific areas. Common in Dachshunds and Chihuahuas.
- Sebaceous adenitis: Immune-mediated destruction of oil glands causing hair loss. More common in Poodles.
While genetic conditions cannot be eliminated, supportive skin care, targeted nutrition, and sometimes light therapy can improve coat quality and comfort.
Can Stress Cause Hair Loss in Pets?
Pets, especially cats, often express emotional distress through overgrooming, a behavior called psychogenic alopecia. This leads to smooth bald patches without redness or irritation, typically on the belly, inner thighs, or legs.
Common feline life stressors that trigger overgrooming:
- New pets or family members
- Moving to a new home
- Changes in routine or schedule
- Loud noises or construction
- Conflict with other household pets
Dogs may show similar symptoms by licking or chewing repetitively at one spot, known as an acral lick granuloma.
Treatment involves addressing the underlying stressor through environmental enrichment, behavioral strategies, pheromone therapy, and sometimes anti-anxiety medication. Our team takes a holistic approach to stress-related conditions, focusing on both the emotional and physical aspects of your pet’s wellbeing.
Does Nutrition Affect Coat Quality?
Healthy coats require proper nutrition. Diets lacking essential fatty acids or high-quality proteins lead to dull, brittle hair that breaks or falls out more easily.
Nutritional factors affecting coat health:
- Omega-3 and omega-6 fatty acid deficiency
- Inadequate protein intake
- Zinc deficiency, especially in Huskies and Malamutes or giant breed puppies
- Poor-quality commercial diets
Overbathing or using harsh shampoos strips the coat’s natural oils, making hair more fragile. Regular grooming improves circulation, removes debris, and keeps coats glossy.
During wellness exams, we provide personalized nutrition advice and may recommend omega-rich supplements when appropriate.
How Do We Diagnose the Cause of Hair Loss?
Every case of alopecia is unique, requiring a systematic approach. Typical diagnostic steps include:
- Comprehensive physical exam: Noting hair loss pattern, location, color, and texture
- Skin scrapings: Checking for mites or parasites under microscopy
- Cytology: Examining cells for bacterial or yeast infections
- Fungal cultures: Testing for ringworm (results take 7-14 days)
- Bloodwork: Evaluating thyroid, adrenal, and metabolic function
- Allergy testing or diet trials: Identifying environmental or food sensitivities
Our veterinary care in Boca Raton includes full-service diagnostic capabilities that provide a clearer picture of what is causing your pet’s hair loss.
What Are the Treatment Options?
Because hair loss stems from many different sources, treatment is highly individualized:
| Cause | Treatment Approach |
| Allergies | Antihistamines, medicated shampoos, omega supplements, immunotherapy |
| Parasites | Prescription preventives, environmental cleaning, medicated treatments |
| Hormonal disorders | Daily medication, hormone therapy, regular blood monitoring |
| Skin infections | Antibiotics (bacterial) or antifungal medications |
| Stress/anxiety | Behavior modification, environmental enrichment, calming therapies |
| Nutritional deficiencies | Diet improvement, supplements |
Our AAHA-accredited hospital offers comprehensive and affordable treatment options, including integrative therapies that reduce inflammation and boost healing.
FAQs
How quickly will hair grow back after treatment?
It depends on the cause. Parasite-related loss typically improves within 4-6 weeks. Hormonal conditions may take 3-6 months once medication is stabilized. Some genetic conditions may not regrow completely.
Is hair loss contagious to humans?
Most causes are not contagious, but ringworm and sarcoptic mange can spread to people. If your pet has circular bald patches with scaly edges, seek prompt evaluation and practice good handwashing.
When should I be concerned about hair loss?
Seek evaluation for bald patches (versus just thinning), excessive scratching or licking, red or scaly skin, spreading or worsening loss, or accompanying symptoms like lethargy, weight changes, or increased thirst.
Can food allergies cause hair loss?
Yes. Food allergies typically affect the face, ears, paws, and rear end. Diagnosis requires an 8-12 week strict elimination diet trial.
Is seasonal hair loss normal?
Some shedding increases in spring and fall during coat transitions. However, bald patches, excessive thinning, or hair that does not regrow is not normal and should be evaluated.
Restoring Your Pet’s Healthy Coat
Most cases of alopecia improve significantly once the underlying cause is identified and treated. Whether hair loss stems from allergies, parasites, stress, or internal disease, a personalized care plan makes all the difference. Do not wait for symptoms to worsen when you notice coat changes.
At Boca Midtowne Animal Hospital, we blend compassionate, Fear-Free care with exceptional diagnostic capabilities to restore your pet’s comfort and healthy coat. Ready to address your pet’s hair loss? Contact us or request an appointment today.
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