Causes of Hair Loss (Alopecia)
Holly Frisby, DVM, MS
Veterinary Services Department, Drs. Foster & Smith, Inc.
There are many diseases and conditions which can cause a cat to lose hair. Some of these may be considered normal, others can indicate a serious disease is present. Most of the conditions which result in hair loss are included below, though some of them may be rare. This extensive list helps you understand why a quick diagnosis may be difficult to make, and various diagnostic tests may need to be performed.
Allergic and irritant contact dermatitis
Description: An allergic reaction following exposure to antibiotics applied to the skin; metals such as nickel; materials such as rubber, wool, and plastic; chemicals such as dyes and carpet deodorizers; or inflammation caused by irritating substances such as poison ivy. Generally requires multiple exposures.
Symptoms: Red skin and small bumps or blisters on the areas of skin that are sparsely haired and directly exposed to the offending substance; itching; hair loss in chronic conditions.
Diagnosis: Patch test, exclusion trials.
Treatment: Restrict exposure to the allergen or contact irritant in the cat's environment; steroids, antihistamines.
Alopecia areata
Description: Thought to be an autoimmune disorder.
Symptoms: Patches of hair loss especially on head, neck, and body; no itching.
Diagnosis: Microscopic examination of hairs; biopsy.
Treatment: Usually recover spontaneously.
Apocrine sweat gland cyst
Description: Rare in cats.
Symptoms: Single, round, smooth nodules with no hair; may appear bluish; usually filled with a watery liquid; most common on head, neck, and limbs.
Diagnosis: Physical exam; biopsy.
Treatment: Surgical removal is optional.
Atopy (allergic inhalant dermatitis)
Description: Allergic reaction to something the cat inhales such as pollen, house dust mites, and mold.
Symptoms: Licking of feet, inflamed ears, itching, redness, and hair loss; sometimes development of infection or hot spots.
Diagnosis: Intradermal or serologic (blood) testing for allergies.
Treatment: Reduce exposure to allergen (what the cat is allergic to), steroids, fatty acid supplements, biotin, antihistamines, shampoos, immunotherapy.
Bacterial infection (pyoderma)
(See Folliculitis)
Description: Often occurs as a result of another condition such as a parasitic, allergic, or hormonal conditon.
Chemotherapy
Description: Loss of hair due to chemotherapy is a concern for cat owners.
Symptoms: Cats lose guard hairs so coat becomes soft and fuzzy; may lose whiskers.
Diagnosis: History.
Treatment: None, hair will regrow after chemotherapy discontinued; may regrow in a different color or texture.
Cheyletiella (rabbit fur mite) mange
Description: Infection with the Cheyletiella mite.
Symptoms: Itching, scaliness; some hair loss, if severe.
Diagnosis: Skin scraping and microscopic examination — the mite is often very difficult to find.
Treatment: Pyrethrin.
Congenital hypotrichosis
Description: Congenital lack of hair.
Symptoms: Kittens born with little or no hair; any hair they are born with is lost by 4 months of age.
Diagnosis: Physical exam; biopsy.
Treatment: None.
Cushing's disease (hyperadrenocorticism)
Description: Caused by an increase in corticosteroids in the body — either due to increased production by the body or as a side effect of high doses or prolonged therapy with corticosteroids.
Symptoms: Hair loss, thinning of skin, hyperpigmentation, easy bruising, seborrhea, comedones (black heads); lethargy, increased thirst and urination, pot-bellied appearance.
Diagnosis: Adrenal gland function tests, urinalysis, chemistry panel, CBC.
Treatment: If due to glandular tumors, selegiline, o,p-DDD (Mitotane), or surgical removal of tumor; if due to high steroid doses, withdraw use of steroids slowly.
Demodectic mange
Description: Infection may be localized or generalized; the generalized form occurs in cats who have a deficient immune system.
Symptoms: Hair loss, scaliness, redness, sometimes itching.
Diagnosis: Skin scraping and microscopic examination.
Treatment: NO Steroids! Rotenone, dilute Amitraz (Mitaban) dips, lime sulfur dips, ivermectin (off-label use*).
Drug or injection reaction
Description: Rare skin reaction to a drug which is inhaled, given orally, or applied topically; more common with penicillins, sulfonamides, and cephalosporins; usually occurs within 2 weeks of giving the drug.
Symptoms: Can vary widely and may include itching, hair loss, redness, swelling, papules, crusts, ulcers, and draining wounds.
Diagnosis: History of being treated with a drug, symptoms, biopsy.
Treatment: Discontinue offending drug; treat symptomatically.
Erythema multiforme
Description: Hypersensitivity reaction to infections or drugs; may also be caused by cancer or other diseases.
Symptoms: Hair loss, 'bull's eye' lesions and vesicles often around mouth, ears, groin, and axilla; in some instances, ulcers develop; depression, fever.
Diagnosis: History, clinical signs, rule out other diseases causing similar signs; skin biopsy.
Treatment: Treat or remove underlying cause.
Facial (preauricular) alopecia; normal hair loss above the eye
Description: Normal decreased density of hair between the eye and ear.
Symptoms: This decreased density of hair starts when cats are 14 to 20 months old; more prominent in short-haired, dark colored cats.
Diagnosis: No diagnostics necessary unless signs of skin disease are present such as redness or scaling.
Treatment: None — normal.
Feline acquired symmetrical alopecia
Description: Rare; originally called 'feline endocrine alopecia'; cause unknown.
Symptoms: Symmetrical hair loss on back of thighs, abdomen, and genital areas; hair easily pulls out; no itching.
Diagnosis: Skin biopsy; tests to rule out other causes of hair loss.
Treatment: None.
Flea allergy dermatitis (flea bite hypersensitivity)
Description: Severe reaction by the cat to the saliva of the flea.
Symptoms: Intense itching, redness, hair loss papules, crusts and scales; sometimes development of infection or hot spots.
Diagnosis: Presence of fleas; reaction to intradermal testing.
Treatment: Flea Control in the environment and on the cat; steroids and antihistamines for the itching.
Folliculitis
Description: Infection of the hair follicles; symptoms usually appear on face, neck, and head.
Symptoms: Pustules develop in the hair follicles and open and form crusts; may itch and develop hair loss.
Diagnosis: Skin scraping; culture; biopsy; look for underlying condition such as allergy or FIV.
Treatment: Antibiotics, usually for 3-4 weeks; treat any underlying condition.
Food allergies
Description: Allergic reaction to something in the diet.
Symptoms: Licking of feet, inflamed ears, itching, redness, and hair loss; sometimes development of infection or hot spots.
Diagnosis: Food elimination trials.
Treatment: Change in diet.
Granulomas
Description: May be due to infections; the body's reaction to foreign material such as plant material (e.g., foxtail) and suture material; other constant irritation; or unknown causes.
Symptoms: Solid, firm nodules of varying sizes; those due to foreign bodies often have draining tracts; may develop hair loss, ulcers, and secondary infections.
Diagnosis: History, clinical signs, biopsy, surgical exploratory.
Treatment: Surgical removal of the foreign body (in the case of plant material, tracts may be extensive and require major surgery); antibiotics if infected; treat any other underlying cause.
Hair loss during pregnancy and nursing ('blowing her coat,' telogen effluvium)
Description: Excess shedding that can also occur in other stressful circumstances such as illness or surgery.
Symptoms: Sudden and widespread hair loss.
Diagnosis: History, clinical signs.
Treatment: Treat any underlying condition; hair will grow back.
Hyperthyroidism
Description: Approximately 1/3 of cats with this disease will have skin lesions; caused by excess secretion of thyroid hormone.
Symptoms: Hair loss; hair easily pulled out; seborrhea; cats may overgroom and cause 'hot spots.'
Diagnosis: Physical exam; blood testing for thyroid hormones.
Treatment: Remove part of thyroid; radioactive iodine therapy; methimazole.
Injection site alopecia
Description: Hair loss at the site of an injection of a medication or vaccine; skin may become thickened; in cats, ulcers may develop.
Symptoms: Hair loss occurs several months after injection; area may become hyperpigmented.
Diagnosis: History and physical examination.
Treatment: None; the condition is permanent.
Lice
Description: Infection with several species of lice.
Symptoms: Variable: itching, hair loss, crusts, rough hair coat.
Diagnosis: Finding lice or nits on skin or hair.
Treatment: Pyrethrin, ivermectin (off-label use*.)
Malassezia
Description: Usually follows some other underlying disease.
Symptoms: Itching, redness, hair loss, greasy scales; if chronic develop hyperpigmentation.
Diagnosis: Skin scraping/smear and microscopic examination, culture.
Treatment: Treat underlying disease; oral ketoconazole; miconazole shampoos.
Psychogenic (neurogenic) dermatitis
Description: Self-licking in cats results in self-trauma; possible causes include anxiety, boredom, stress (e.g., new member in household.)
Symptoms: Symmetrical hair loss, sometimes ulcers, on abdomen, groin, along the back.
Diagnosis: Exclude other causes; history important.
Treatment: Relieve underlying cause e.g., anxiety; restrict licking; behavior modifying medication may be necessary.
Pyoderma-superficial
(see Folliculitis)
Ringworm
Description: Infection with several types of fungus.
Symptoms: Hair loss, scaliness, crusty areas; some itching.
Diagnosis: Culture.
Treatment: Miconazole, lime sulfur dips; oral griseofulvin or itraconazole; ringworm vaccine.
Sebaceous adenitis
Description: Sebaceous glands are destroyed, cause unknown; very rare in cats.
Symptoms: Circular areas of crusts and scales on head, ears, and neck; hair pulls out easily, leaving skin exposed.
Diagnosis: Clinical signs, skin biopsy.
Treatment: Antiseborrheic shampoos, fatty acid supplements; in more severe cases, steroids, retinoids.
Seborrhea
Description: Can be primary (inherited) or secondary (resulting from other disease processes such as FeLV, FIP, FIV, ringworm, and parasites.)
Symptoms: Scales; depending upon the type, may have a dry or oily coat; odor; some scratching; may see hair loss.
Diagnosis: Blood tests, skin scrapings, etc. to find underlying cause.
Treatment: Treat underlying cause if present; antiseborrheic shampoos; fatty acid supplements.
Solar dermatosis
Description: Skin reaction to sunlight; more common in cats with white ears.
Symptoms: Redness, hair loss, and scaling on nose and ears, later crusts and ulcers.
Diagnosis: History, breed, physical exam, skin biopsy.
Treatment: Must avoid further sun exposure, especially from 9 am to 3 pm; sunblock, steroids.
Stud tail (tail gland hyperplasia)
Description: A sebaceous gland (on the top of the tail near its base) enlarges; most often occurs in confined, unneutered males.
Symptoms: Oily area, hair loss, and crusts on area over gland; may become hyperpigmented.
Diagnosis: Clinical signs.
Treatment: Castration usually does not resolve the condition; antiseborrheic shampoos, retinoids; if confined, allow cat more freedom.
* off-label use: medication used to treat a condition for which it was not developed (or licensed). A large number of medications fall under this category. Research has almost always been performed to determine the effectiveness and safety of the product, but the manufacturer has not undertaken the lengthy process required for licensure.
References
Birchard, SJ; Sherding, RG (eds) Saunders Manual of Small Animal Practice. W.B. Saunders Co. Philadelphia, PA; 1994.
Greene, CE (ed). Infectious Diseases of the Dog and Cat. W.B. Saunders Co. Philadelphia, PA; 1998.
Griffin, C; Kwochka, K; Macdonald, J. Current Veterinary Dermatology. Mosby Publications. Linn, MO; 1993.
McKeever, PJ; Harvey, RG. Skin Diseases of the Dog and Cat. Iowa State University Press. Ames, Iowa; 1998.
Paterson, S. Skin Diseases of the Cat. Blackwell Science Ltd. London, England; 2000.
Paterson, S. Skin Diseases of the Dog. Blackwell Science Ltd. London, England; 1998.
Scott, D.; Miller, W.; Griffin, C. Muller and Kirk's Small Animal Dermatology. W.B. Saunders Co. Philadelphia, PA; 1995.
|
|
|
