Causes of Scratching & Licking
Holly Frisby, DVM, MS
Veterinary Services Department, Drs. Foster & Smith, Inc.
In addition to allergies, there are other diseases which can cause your cat to scratch, lick, or pull on her hair. A short description of these conditions such as mange, cancer, behavioral problems, and infections, along with their diagnosis and treatment, are shown in the list below. Many of the more uncommon conditions are included as well. This large number of conditions 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; and 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.
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, Pyoderma-deep)
Description: Often occurs as a result of another condition such as a parasite, allergic, or hormonal conditon.
Bee, wasp, hornet stings
Description: Skin reactions can vary dramatically in severity.
Symptoms: Immediately after the bite, see swelling, redness, pain, possibly itching; subsequently may develop extensive ulcers with draining; may develop hives or anaphylaxis.
Diagnosis: History, physical exam.
Treatment: Antihistamines, steroids; wet dressings if ulcerated; protect the area from self-inflicted trauma.
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.
Chiggers (harvest mites)
Description: Seasonal disease caused by larvae of the chigger.
Symptoms: Itching, bumps usually on feet, abdomen, folds at base of ears.
Diagnosis: Visualization of mite larvae or microscopic examination of skin scraping.
Treatment: Pyrethrin.
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.
Ear Mites
Description: Infection with Otodectes.
Symptoms: Intense itching of ears, redness, dark crumbly discharge in ears.
Diagnosis: Direct visual or microscopic examination of ear discharge.
Treatment: Clean ears and apply medication containing pyrethrin (Ear Miticide.)
Eosinophilic plaques
Description: Part of the common eosinophilic allergic syndrome in cats which includes eosinophilic granulomas, miliary dermatitis, and rodent ulcers.
Symptoms: Intense itching; raised, oval, oozing, and possibly ulcerated lesions; may be single or multiple; often on abdomen and thighs.
Diagnosis: Microscopic examination of swab from lesion, biopsy, CBC (find increased eosinophils); look for underlying cause, e.g., parasites, food allergy, atopy.
Treatment: Treat underlying cause if found; corticosteroids; fatty acid supplements; immunosuppressive drugs in severe cases.
Epitheliotropic lymphoma (mycosis fungoides)
Description: Rare cancer of T lymphocytes seen in older cats; may be associated with FeLV.
Symptoms: Redness, itching, scales, ulcerated nodules.
Diagnosis: Needle or other biopsy.
Treatment: Poor response to treatments which include chemotherapy, surgical removal, retinoids, fatty acids.
Feline acne
Description: Skin condition of unknown cause which may occur as single episode or continue as chronic condition; most commonly seen on the chin; can develop into a more serious, deep infection if not treated.
Symptoms: Comedones (black heads) on lips and chin, later developing pustules and small nodules; may itch - especially in chronic cases; chin may become swollen; can become secondarily infected.
Diagnosis: Physical exam; tests to rule out underlying causes or diseases with similar symptoms; skin biopsy.
Treatment: Mild: antiseborrheic shampoos, antibacterial creams, topical Vitamin A; Severe: antibiotics, fatty acids, retinoids (use with caution, can be irritating).
Feline pox
Description: Viral disease; outdoor cats more commonly affected; presumably transmitted by bite wounds.
Symptoms: Nodule at the site of a previous bite wound; progresses to multiple nodules which may ulcerate and have crusts; may itch.
Diagnosis: History, physical exam; biopsy; specialized testing to identify the virus.
Treatment: Lesions usually resolve in 3-4 weeks; anitbiotics for any secondary infection; antihistamines for itching; NO steroids; in some cats, lesions progress and do not respond to treatment.
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.
Hookworms
Description: Infection with the larvae (immature forms) of hookworms.
Symptoms: Red bumps, usually on feet, rough foot pads, abnormal nail growth, itching.
Diagnosis: Physical exam, history of poor sanitation.
Treatment: Treat for intestinal infection; move cat to different environment.
Hot spots (acute moist dermatitis)
Description: Result from allergies, flea bites, mange, anal gland disease, poor grooming, ear infections, plant awns or burs, arthritis.
Symptoms: Hair loss; red, moist, oozing skin; constant licking or scratching.
Diagnosis: Physical exam and history.
Treatment: Treat underlying condition; clean area; apply Domeboro solution; topical and/or oral antibiotics and steroids.
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.
Miliary dermatitis in cats
Description: Part of the common eosinophilic allergic syndrome in cats which includes eosinophilic granulomas, eosinophilic plaques, and rodent ulcers; may also be associated with infections, autoimmune diseases, hormonal disorders, and nutritional deficiencies.
Symptoms: Multiple small crusty bumps, usually over hips, neck, and back of thighs; moderate to severe itching.
Diagnosis: Microscopic examination of swab from lesion, biopsy, CBC (find increased eosinophils); look for underlying cause, e.g., parasites, food allergy, atopy.
Treatment: Treat underlying cause if found; corticosteroids; fatty acid supplements.
Notoedric mange
Description: Infection with the Notoedres mite.
Symptoms: Intense itching and self-trauma, skin thickening, gray crusts develop.
Diagnosis: Skin scraping and microscopic examination.
Treatment: Lime sulfur dips, ivermectin (off-label use*.)
Pemphigus foliaceus
Description: The most common form of pemphigus in the cat; an autoimmune disease.
Symptoms: Often affects feet and head; starts with pustules and progresses to severe crusting; depigmentation of the nose is common; itching may occur; if footpads and nails affected often see lameness; symptoms wax and wane; severely affected cats may have fever and loss of appetite.
Diagnosis: History, physical exam, skin scraping and biopsy.
Treatment: Corticosteroids, other immunosuppressive therapy, gold injections.
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.
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.
Tick bites
Description: Ticks cause a local inflammation in the skin, even when the entire tick is removed.
Symptoms: Nodule and redness at site of the bite; may itch and develop crusts; may last several months.
Diagnosis: History.
Treatment: Remove the tick; use a tick preventative; allow nodule to resolve on its own.
Urticaria (hives)
Description: Reaction, often allergic, to insect bite, drug, vaccine, sunlight, etc.
Symptoms: Multiple swellings, with hair standing up over swellings; may itch.
Diagnosis: History, physical exam.
Treatment: Often resolves on its own; in the case of allergic reactions, antihistamines, epinephrine or corticosteroids depending upon severity.
Xanthoma
Description: Result of abnormality in lipid metabolism; can be a result of diabetes mellitus or due to hereditary affecting lipid metabolism (hyperlipidaemia)
Symptoms: White or yellow nodules, usually on head, extremities, and bony prominences; often painful and itchy.
Diagnosis: Physical exam and history; biopsy.
Treatment: Treat underlying disease; change diet; lesions often recur if surgically removed.
* 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.
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