Feline Health Topics for veterinarians October- Volume 13, Number 4 The Greasy, Flaky, or Crusty Cat William H. Miller, Jr., VMD, DACVD Editors Note: This article is excerpted from Dr. cat. It is recognized most commonly in Persian cats William Miller's presentation at the Tenth Annual as a hereditary disease with an autosomal recessive Fred Scott Feline Symposium on July 17-19, 1998 at mode of inheritance. Signs are present at or near the Veterinary Education Center on the Cornell Uni­ birth; some kittens are more severely affected than versity campus in Ithaca, New York. The seminar others. The coat is greasy and unmanageable, and was sponsored by the Cornell Feline Health Center, ceruminous otitis and multiple comedones are present. Cornell University College of Veterinary Medicine The diagnosis of primary seborrhea is made by his­ Continuing Education Department, and several cor­ tory and skin biopsy. There is no cure for the porate sponsors. underlying skin disease, but frequent bathing is help­ ful in maintaining a more normal coat. The effective­ Visible flakes or grease, be they localized or general­ ness of retinoids is unproven. ized, indicate that the normal process of keratiniza- tion has been disrupted. If the cause of the disruption Localized Disease can be found and corrected, the problem will disap­ Feline Acne: A common problem, feline acne can be pear without additional treatment in approximately a one-time disorder, a chronically relapsing condi­ 45 days. tion, or a permanent problem. Comedones develop PRIMARY KERATIN IZ ATI ON DISORDERS around the lips and on the chin. Simple cases may require no treatment, but if they do, the response to Generalized Disease topical treatment is usually satisfactory. Cats with Unlike in the dog where primary seborrhea is fairly more severe or resistant disease should be examined common, generalized primary seborrhea is rare in the carefully for secondary bacterial or M alassezia infec­ tion. Fatty acid supplements (e.g., DermCaps®) can be of some benefit in chronic cases. Treatment with retinoids shows promise but very few cases have been reported. Inside this issue... Stud Tail: Stud tail, an accumulation of The Greasy, Flaky, or Crusty Cat pagel keratosebaceous debris along the entire dorsal sur­ face of the tail, is an uncommon problem seen most Subject Index page 5 commonly in intact males but also in neutered males ACVIM Medical Forum page 8 and altered and unaltered females. Castration does not resolve the problem but may slow its progression. Frequent cleaning with a degreasing shampoo (e.g., Feline Health Topics 2 those that contain benzoyl peroxide) helps keep the fe lis; infection indicates that the cat has some serious condition under control. underlying immunosuppressive disease (e.g., FIV infection). Diagnosis is made by microscopic exami­ SECONDARY KERATINIZATION DISORDERS nation of skin scrapings. Endocrine Disease The incidence of Cheyletiella infestation appears Hyperthyroidism, diabetes mellitus, and hyperadreno- to have decreased in recent years, probably as a result corticism are endocrine disorders that may affect of increased use of flea control products that kill this normal skin keratinization. Improvement in the skin mite as well. With the popularity of Program® and condition accompanies correction of the underlying Advantage®, the incidence may increase again. disorder. Cheyletiellosis has a caudodorsal distribution with variable pruritus. Diagnosis is difficult, especially Infectious Disease when the cat is itchy. The best way to demonstrate the mite is with a flea comb or vacuum cleaner; the mass Generalized disease as a result of Microsporum canis of hair and scale that is collected is then evaluated by infection is uncommon except in longhaired kittens. means of flotation techniques. At best, these tech­ When generalized disease is recognized, especially niques yield positive results in 65% of infected cats. in an adult cat, a search for some underlying cause The ultimate test is response to treatment. Ivermectin should be undertaken. (0.3 mg/kg ql0-14d) receives widest use. Use of a Malassezia infection is a well known cause of topical insecticide at the first treatment can accelerate skin disease in the dog. Infection occurs in cats as the response in a very itchy cat. wel 1, but so few cases have been described that details Lice and fur mites cause scaly lesions but their on underlying causes or treatments are sketchy. size (lice) or numbers (fur mites) make diagnosis Parasitic Disease straightforward. Ectopic ear mites can cause disease on the body and are difficult to find in this location. Seborrheic demodicosis is usually caused by Demodex However, these cats invariably have otitis externa in addition to the disease present on other parts of the body. Ectopic infestation is best treated with topical insecticides or ivermectin. The ultimate purpose o f the Cornell Feline Health Center is to improve the health of cats everywhere by developing methods to prevent or Metabolic Disorders cure feline diseases, and by providing continuing education to veteri­ narians and cat owners. All contributions are tax-deductible. Director: James R. Richards, D.V.M. Cats with liver or pancreatic disease usually will Administrator: Iva Heim develop a generalized greasy coat, generally occur­ Secretaries: Gwendolyn M. Frost Kathleen M. Mospan ring late in the course of the disease. The prognosis Pamela E. Sackett for these cats’ skin disease is dependent on the Sheryl A. Thomas outcome of treatment of the underlying condition. ©1998 by Cornell University on behalf of the Cornell Feline Health Center, College of Environmental Disorders Veterinary Medicine, Ithaca, NY 14853. Phone: (607) 253-3414 Fax: (607) 253-3419 All rights reserved. Permission to reprint se­ Low humidity will dry a cat’s coat. This is especially lected portions must be obtained in writing. true for cats that are heavy groomers, because with Cornell University is an equal opportunity, af­ firmative action educator and employer. grooming, water is put on the hair and skin but will Printed on recycled paper. evaporate rapidly when the relative humidity is be­ low 40%. If one cat in a multiple cat household is 3 dryer than the others, it would be appropriate to (e.g., pustules, erosions, or ulcers) occur, but are determine if the cat has an underlying skin condition rarely recognized because they are hidden by the cat’s that is increasing its grooming. If the flakiness is fur. As the lesions mature, crusting occurs. The crust strictly due to low humidity, topical skin moisturizers by itself offers few diagnostic clues, but the distribu­ will work, but most cats fail to tolerate prolonged use. tion of the lesions and exudative cytology of a freshly crusted lesion helps define the disease process. Since THE CRUSTY CAT these disorders are very serious, the tentative diagno­ Miliary Dermatitis sis should be confirmed by skin biopsy and appropri­ ate blood testing. The most common crusting skin disorder of the cat is miliary dermatitis. In the early era of feline dermatol­ True Autoimmune Diseases ogy, miliary dermatitis was thought to be a specific In cats, the most common true autoimmune disease is disease entity. Today, we know that miliary derma­ pemphigus foliaceous. Lesions are typically general­ titis is a reaction pattern in the cat and not a specific ized, but those on the face, ears, and feet are most disease. Diseases seen within this reaction pattern noticeable. Careful clipping usually will uncover include: unnoticed lesions. Treatment is life-long and in­ Bacterial folliculitis Dermatophytosis Otodectes volves the use of corticosteroids (e.g., prednisolone at 4.4 mg/kg/day, or dexamethasone at 0.4 mg/kg/ Cheyletiella infestation Feline scabies Pediculosis day), cytotoxic agents (e.g., chlorambucil at 2-6 mg/ Demodicosis Trombiculosis Fur mite infestation m2 BSA q24h), or gold injections. Antibiotics are needed at the onset of treatment and must be consid­ Nutritional deficiency Flea allergy Atopy ered at any “flair” in the pemphigus. The lesions of Food allergy Insect allergy Pemphigus bacterial folliculitis are impossible to differentiate Lupus erythematosus Drug reaction EM/TEN from those of pemphigus in the cat receiving corti­ costeroids. Mast cell disease Idiopathic Immune-mediated Diseases With the high quality of today’s cat foods, nutri­ tional causes are very rare but all other causes are seen With the exception of systemic lupus erythematosus, with some regularity. The history, distribution of the most immune-mediated disorders in cats are curable. lesions, and exudative cytology helps trim the list but If the antigen triggering the reaction can be found and rarely leaves only one disease to investigate. By eliminated, the disease progression should halt and systematic elimination of the appropriate differen­ the cat’s need for immunosuppressive treatments tials, the primary disease will be found and the should be eliminated or short-lived. number of idiopathic cases should be nonexistent. Drug reactions are the most common immune- Immune-mediated Disorders mediated disorders in cats, and can occur with any drug. Reactions can occur any time after an initial Immune-mediated skin diseases are far less common period of sensitization (7 to 14 days). They usually in the cat than in the dog. True autoimmune dis­ occur within the first 3 weeks of drug administration; eases—disorders where the body attacks normal self— if the drug was used before, reactions can appear very appear to be less frequent than immune-mediated quickly. If the cat is receiving multiple drugs, all are disorders where the body is attacking altered self, or suspect, but the last drug incorporated is the most the skin is accidently destroyed in an immune com­ plex disease. In both disease categories, skin lesions (continued on next page) Feline Health Topics 4 suspect. Skin biopsy often confirms the diagnosis, or noma which remains in the epidermis for long peri­ at least eliminates other potential causes.