Decoding Hair Loss in Pets: From Allergies to Hormones

If your pet’s once-luxurious coat is thinning or bald patches are beginning to appear, it’s time to look beneath the surface. The key is to uncover why it’s happening and address the problem at its source. What causes hair loss in pets? Hair loss (alopecia) in dogs and cats is most commonly caused by allergies, parasites, skin infections, hormonal imbalances, stress, or nutritional deficiencies. The pattern, location, and presence of itching help determine the underlying cause. Most cases improve significantly once properly diagnosed and treated.

At MountainView Veterinary Hospital in Denville, NJ, our team blends advanced diagnostic medicine with a compassionate, family-oriented approach to care. As a Certified Feline Friendly practice, we understand how to handle even the most anxious pets gently and respectfully. From medical management to integrative therapies like acupuncture, laser therapy, and herbal treatments, we provide a complete care path that restores your pet’s comfort, and their coat.

What Is Alopecia in Dogs and Cats?

Alopecia is the medical term for partial or total hair loss. It is not a disease itself but a symptom indicating an underlying condition affecting the skin, hair follicles, or internal systems.

Hair loss (alopecia) differs from normal shedding in several ways:

Normal Shedding Abnormal Hair Loss (Alopecia)
Even thinning across body Bald patches or localized loss
Seasonal pattern Occurs any time of year
No skin changes Redness, scaling, or irritation
Hair regrows normally Hair doesn’t regrow or grows abnormally
No excessive scratching Often accompanied by itching or licking

The pattern, texture, and presence of other symptoms help veterinarians determine the likely cause. At MountainView, our experienced team uses these clues along with diagnostic testing to pinpoint the problem quickly and accurately.

What Are the Most Common Causes of Hair Loss in Pets?

Can Allergies Cause Hair Loss in Dogs and Cats?

Yes. 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 follow, leading to scratching, licking, and bald spots.

Common allergens include:

  • Pollen, grass, and mold (environmental/seasonal)
  • Dust mites (year-round)
  • Food proteins (chicken, beef, dairy, wheat)
  • Flea saliva (even one bite can trigger reactions)

General pet allergies often cause hot spots and generalized itching, while flea allergies typically affect the tail base, lower back, and inner thighs.

The importance of year-round parasite prevention for pets cannot be overstated. Consistent prevention reduces flare-ups and keeps skin healthy. Our veterinarians also offer allergy testing, prescription diets, and long-term management strategies for persistent cases.

Can Parasites and Skin Infections Cause Bald Patches?

Yes. External parasites cause hair loss by irritating the skin or damaging hair follicles directly.

Common parasites causing hair loss:

Parasite Hair Loss Pattern Other Signs
Fleas Lower back, tail base, inner thighs Intense itching, flea dirt visible
Demodex mites Face, paws, patchy areas Mild itching, red skin
Sarcoptes mites (scabies) Ears, elbows, abdomen Severe itching, crusting
Ringworm (fungal) Circular bald spots Scaly edges, can spread to humans

Spotting and treating mites in dogs is essential, as these microscopic parasites burrow into or live on the skin. Puppies and dogs with auto-immune conditions are more susceptible. Ringworm, despite its name, is a fungal infection that forms circular bald spots with red, scaly edges and can spread to humans. Early diagnosis is critical. Other bacterial and yeast skin infections can cause hair loss due to the intense itchiness, leading to excessive scratching.

At MountainView, our diagnostic services include in-house cytology, fungal cultures, and skin scrapings. These quick, painless tests help us identify the exact cause and begin treatment immediately.

Can Hormonal Problems Cause Hair Loss in Pets?

Yes. Internal hormone imbalances frequently cause gradual, symmetrical hair loss that typically is not itchy or painful. These changes may go unnoticed at first, but over time, coat texture and color can shift dramatically.

Key hormonal conditions causing alopecia:

Condition Species Affected Hair Loss Pattern Other Signs
Hypothyroidism Dogs Symmetrical on trunk, tail (“rat tail”) Weight gain, lethargy, cold intolerance
Cushing’s disease Dogs Sides of body, thin skin Pot belly, increased thirst/urination
Hyperthyroidism Cats Patchy, unkempt coat Weight loss, increased appetite
Sex hormone imbalance Dogs, Cats Flanks, rear end, genital area Behavioral changes, enlarged nipples

 

Hypothyroidism in dogs occurs when the thyroid gland doesn’t produce enough hormones, slowing metabolism. Affected dogs often gain weight, become lethargic, and develop dry, thinning coats. Cushing’s disease in dogs stems from excess cortisol production, causing a pot-bellied appearance, fragile skin, and hair loss along the sides of the body.

Sex hormone imbalances can also cause significant hair loss. In intact male dogs, testicular tumors can produce excess estrogen, leading to symmetrical hair loss on the flanks, chest, and genital area, along with enlarged mammary glands and attraction from other male dogs. Intact females may develop hair loss related to ovarian cysts or tumors affecting estrogen levels. Spaying or neutering often resolves hormone-related alopecia in these cases.

Human topical hormone creams pose an often-overlooked risk to pets. When owners use estrogen creams, testosterone gels, or other hormone replacement therapies and pets lick the application site or have skin-to-skin contact, they can absorb these hormones.  If you use topical hormone medications, apply them to areas your pet cannot reach, wash your hands thoroughly, and cover the application site with clothing.

Regular blood work for your dog or cat is crucial. Routine lab testing can reveal hormone imbalances long before symptoms become obvious.

Are Some Breeds More Prone to Hair Loss?

Yes. Some breeds are genetically predisposed to certain forms of alopecia.

Breed-related hair loss conditions:

  • Color dilution alopecia: Affects dogs with diluted coat colors (blue, fawn, silver). Common in Dobermans, Weimaraners, and Italian Greyhounds.
  • Canine flank alopecia: Causes 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: More common in poodles, though it can occur in any pet, causing immune-mediated destruction of sebaceous (oil) glands leading to hair loss.

Although genetic conditions cannot be cured, we can help manage them through supportive skin care, nutrition, and light therapy to maintain coat health.

Can Stress Cause Hair Loss in Pets?

Yes. Pets, especially cats, often express emotional distress through overgrooming. This behavior, called psychogenic alopecia, leads to smooth bald patches without redness or irritation.

Common feline life stressors triggering overgrooming:

  • New pets or family members in the home
  • Moving to a new environment
  • Changes in routine or schedule
  • Loud noises or construction
  • Conflict with other household pets

Dogs may show similar symptoms, licking or chewing at one spot repetitively. We approach these cases holistically, using behavioral strategies, pheromone therapy, herbal calming support, and when needed, anti-anxiety medication. Because our doctors are trained in acupuncture and alternative medicine, we can also offer integrative therapies to reduce chronic stress naturally.

Can Poor Nutrition Affect My Pet’s Coat?

Yes. 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 or biotin deficiency
  • Poor-quality commercial diets

Overbathing or using harsh shampoos also strips the coat’s natural oils, making hair more fragile. Regular grooming improves circulation, removes debris, and keeps the coat glossy. During exams, we provide personalized grooming and nutrition advice, including herbal or omega-rich supplements when appropriate.

How Is the Cause of Hair Loss Diagnosed?

Every case of alopecia is unique, and pinpointing the cause requires a systematic approach. At MountainView, diagnosis typically includes:

  1. Comprehensive physical exam: Noting hair loss pattern, location, color, and texture
  2. Skin scrapings: Checking for mites or other parasites under microscopy
  3. Cytology: Examining cells for bacterial or yeast infections
  4. Fungal cultures: Testing for ringworm (results take 7-14 days)
  5. Bloodwork: Evaluating thyroid, adrenal, or metabolic function
  6. Allergy testing or diet trials: Identifying environmental or food sensitivities

Our full-service hospital offers comprehensive diagnostics to determine the cause of your pet’s hair loss. These tools give us a clearer picture of your pet’s internal balance, helping us address root causes rather than just symptoms.

What Are the Treatment Options for Hair Loss in Pets?

Because hair loss can stem from many different sources, treatment is highly individualized based on the underlying cause.

Cause Treatment Approach
Allergies Antihistamines, medicated shampoos, omega supplements, immunotherapy
Parasites Prescription preventives, environmental cleaning, medicated dips
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, herbal therapy, omega supplementation

Integrative treatment options: We often combine Western medicine with integrative approaches like laser therapy to reduce inflammation, acupuncture to boost healing, and PEMF therapy to improve circulation and cellular repair. These holistic modalities complement medical treatment, accelerating recovery and supporting long-term wellness.

How Can I Prevent Hair Loss in My Pet?

Prevention starts with proactive care. Here’s how to keep your pet’s coat healthy and strong:

  • Parasite prevention: Year-round protection against fleas, ticks, and mites
  • Quality nutrition: High-quality diet tailored to age, breed, and health status
  • Regular grooming: Brushing and coat checks to detect problems early
  • Routine wellness exams: Annual or biannual visits to establish baselines and monitor changes
  • Stress reduction: Stable routines and environmental enrichment

Our wellness visits include diagnostic screenings such as thyroid panels, heartworm tests, and fecal checks to identify early disease. Routine wellness care promotes pet health by catching subtle changes before they progress.

Frequently Asked Questions About Hair Loss in Pets

How quickly will my pet’s hair grow back after treatment? Hair regrowth depends on the underlying cause. Parasite-related hair loss often improves within 4-6 weeks. Hormonal conditions may take 3-6 months to show significant regrowth once medication is stabilized. Some genetic conditions may not regrow hair completely.

Is hair loss in pets contagious to humans? Most causes are not contagious. However, ringworm (a fungal infection) and sarcoptic mange can spread to humans. If your pet has circular bald patches with scaly edges, seek veterinary care promptly and wash your hands after handling.

When should I be concerned about my pet’s hair loss? Seek veterinary evaluation if you notice bald patches (not just thinning), excessive scratching or licking, red, irritated, or scaly skin, hair loss spreading or worsening, or any accompanying symptoms like lethargy, weight changes, or increased thirst.

Can food allergies cause hair loss? Yes. Food allergies can cause itchy skin, ear infections, and hair loss, typically affecting the face, ears, paws, and rear end. Diagnosis requires a strict elimination diet trial lasting 8-12 weeks.

Is seasonal hair loss normal? Some shedding increases in spring and fall as coats transition. However, bald patches, excessive thinning, or hair that doesn’t regrow is not normal seasonal shedding and should be evaluated.

Ready to Restore Your Pet’s Healthy Coat?

Most cases of alopecia improve significantly once the cause is identified and treated. Whether your pet’s hair loss stems from allergies, parasites, stress, or internal disease, a personalized care plan makes all the difference.

If you’ve noticed your pet’s coat changing, don’t wait for symptoms to worsen. Schedule an appointment with our experienced team at MountainView Veterinary Hospital. For sudden or severe cases, our 24/7 emergency triage service connects you with a veterinarian any time of day or night.

Our mission is simple: to blend compassionate care with exceptional medicine, because at MountainView, your pet’s health and happiness are always our top priorities.