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Cats - Skin, Mouth & Ear problems

 

Cat with stethoscope

Atopy

Atopy is a skin hypersensitivity (allergy) reaction common in cats. The most common sign is hair loss with or without dermatitis. Diseases of the eosinophilia granuloma complex are thought to be allergic manifestations. Head and neck itching is common. Less common manifestations include self-mutilation, foot chewing, and recurrent ear infections. Because of excessive licking, cats may have an increased number of hairballs or constipation caused by hair ingestion.

Diagnosis of this problem can be carried out buy using intradermal skin testing. However your vet will probably be strongly suspicious of atopy on the basis of clinical examination and may be able to diagnose the problem on the basis of response to treatment.

Hyposensitisation is the treatment of choice but perfectly adequate responses may be seen with corticosteroid therapy. Addition of fatty acid supplements to the diet, and antihistamines may also be of use.

The prognosis is excellent if there is good response to treatment.

Dermatophytosis

Frequently called ringworm, is a fungal infection affecting the skin and nails. About 95% of feline cases are caused by Microsporum canis. The cat is also infected by Trichophyton species. Direct exposure to a fungus does not necessarily result in an infection, and an infection does not always cause clinical signs. Long-haired cats are more likely to have symptomatic infections. The typical incubation period is 1-4 weeks, but some cats remain asymptomatic carriers for long periods of time. Lesions may have the typical appearance of circular areas of hair loss, but their appearance can be diverse.

Diagnosis is carried out by a Wood's lamp examination which is an ultraviolet light that causes some strains of ringworm to fluoresce. Positive confirmation is by fungal culture from areas affected by the disorder. this may take 7-14 days to perform.

Treatment can be carried out with both topical shampoos or oral medication. It is extremely important to isolate any affected animals and clean and disinfect the environment as thoroughly as possible.

The prognosis is generally good if aggressive therapeutic measures are taken.

This infection can spread easily to other animals and people. The organism can remain in the environment for up to one year.

Ear Mites

Infestation with ear mites (Otodectes cynotis), is common in cats. The mites live on the skin surface; they are non-burrowing but irritate the ear, filling the canal with wax, blood, and mite exudate. Some cats develop intense irritation with the presence of only a few mites. The immune system appears to limit infestations in most mature cats. Infested cats will often shake the head and twitch or rub the ears. Brownish-black debris is usually evident in the external canals. The presence of a brownish ear discharge and evidence of scratching at the ears is highly suggestive of ear mites. Under ear examination the white mites are often seen moving. Although some cats have an extreme response to the presence of ear mites, others are relatively asymptomatic. 

Topical ear drops can be used for treatment of ear mites and selamectin can be applied to the skin.

The prognosis is good with appropriate treatment.

Eosinophilic Granulomas

Eosinophilic granulomas is a form of skin reaction that develops in response to underlying allergy (insects, food, atopy) or other immune-mediated factors; bacteria, viruses, and stress are proposed to play a role in some cases. The three forms of the syndrome are eosinophilic plaque, linear (collagenolytic) granuloma, and indolent (rodent) ulcer.

Linear granulomas commonly present as balding, well-circumscribed bands of tissue on the caudal thighs. Related lesions may also occur on the footpads, in the pharynx, and on the tongue. Some cats have a swollen lower chin or lip. Lesions of eosinophilic plaque are well demarcated raised areas of hair loss and ulceration, usually on the ventral abdomen and medial thighs. Associated lesions are extremely itchy and remain moist because of constant licking. Indolent ulcers are usually well, circumscribed areas of ulceration on the upper lip; lesions may be bilateral or unilateral.

Biopsy of the skin offers the most valuable tool for accurate diagnosis.

The most commonly used treatment is corticosteroid therapy, other immunomodulating and hormonal drugs may be used but tend to generate more side effects.

Prognosis

The prognosis is good in most cats, although continuous or repeated therapy may be needed. The prognosis is better if an underlying condition can be identified and treated.

Fight Wound Infections

Cats are very territorial animals, bite and fight wounds are common occurrences. Most bite wounds penetrate to substantial depth within the tissue without leaving large skin wounds. Closure of the skin wound occurs rapidly and the bacteria are trapped in the underlying tissues. The wound then becomes swollen and painful and develops lameness (if on a leg). Abscess formation occurs about 3 to 5 days after the bite. If not lanced, it will usually rupture by 7 days. Some cats develop chronic draining tracts due to resistant bacteria or the presence of foreign bodies within the wound, or immunosuppressive states usually associated with the feline immunodeficiency virus (FIV) or the feline leukemia virus (FeLV).

If a bite wound occurs in a location that does not have loose skin, such as a distal extremity, the infection will dissect through tissues, resulting in diffuse swelling instead of an abscess. Lethargy, inappetance, fever, and lameness are the early signs. Areas of swelling anywhere on the body of a cat showing the appropriate clinical signs should arouse suspicion.

Outdoor cats or cats in multicat households with a history of fighting are at highest risk. Because of the high incidence of this disease, a bite wound infection should be suspected first for draining tracts, especially if fever and a history of fighting are present.

Treatment is with appropriate antibiotic therapy and surgical drainage of abscesses. In intact tom cats castration may help to reduce the incidence of this problem by mollifying aggressive behaviour.

The prognosis for fight wound infections is excellent with proper diagnosis and antibiotic therapy. The FIV and FeLV viruses make the cat susceptible to repeated and resistant infections and should be tested for if there is difficulty in resolving the problem.

Food Allergies

Food hypersensitivity, or food allergy, is an adverse reaction to a component of the diet; protein is the most consistent offender. 

Feline food allergy most commonly presents as hair loss and severe non-seasonal skin irritation of the face and neck; classic miliary lesions may be present. Some cats will self-mutilate, leading to ulcerative lesions. Occasionally, generalized skin irritation may be found. 

Elimination diet testing remains the only reliable method for confirming food allergy in the cat. Some improvement is noted in most cats after 6 weeks of a food trial. 

Skin scraping and fungal culture should be performed to eliminate parasites and ringworm as the cause of irritation. 

Intradermal skin testing and blood testing are generally considered unreliable for diagnosis of food allergy. With these tests, a cat may have a positive reaction to foods it has never eaten. Many lamb-based commercial diets contain potentially allergenic substances, including other sources of protein. Lamb is not inherently hypoallergenic. Most cats with food allergy are poorly responsive or non-responsive to corticosteroids. Lack of response should raise one's index of suspicion. Atopy and flea allergy frequently coexist with food allergy

Avoidance of the offending foodstuff is the most appropriate treatment.

The prognosis is good as long as the offending allergen can be identified and avoided. 

Flea-Allergy Dermatitis

The most common allergic skin disease of cats is due to hypersensitivity reactions to flea saliva. These produce clinical signs of itching, excessive licking, and scratching. Some cats are secretive in these activities, so many owners are unaware of their occurrence. Papular, crusty eruptions, known as miliary dermatitis, and varying amounts of hair loss often result. The pattern may be generalized, localized to the head and neck, the back of the rear legs, or to the tailhead region. Flea-allergy dermatitis is one of the causes of eosinophilic plaques and eosinophilic ulcers.

The presence of itching, hair loss, and miliary dermatitis in cats with fleas or flea feces (flea dirt) should cause one to suspect flea allergic dermatitis.

This disease is very common in climates that are warm enough to support a flea population.

Treatment involves good flea control (see Fleas page) and anti-inflammatory drugs such as prednisolone or injectable corticosteroids. If skin damage is severe then antibiotics to control secondary infection may be required. Only a few fleas are required to produce marked clinical signs.

This is not a fatal disease. However, the goal of therapy is to restore quality life to the cat. The prognosis for doing so is good with either good flea control or the use of corticosteroids.

Gingivitis/Stomatitis/Pharyngitis

Lymphocytic-plasmacytic gingivitis is a common disease causing inflammation, ulceration, and proliferation of the soft tissues of the mouth. Middle-aged cats are usually affected. The area of the mouth most commonly affected is the back of the mouth around the entrance to the pharynx. The gums, pharynx, soft palate, lips, and tongue are also commonly affected. The cause is unknown but is felt to be multifactoral with an immune-mediated component, possibly representing a hypersensitivity to oral bacterial antigens. However, it is unlikely that bacterial infection is the primary cause, as antibiotic therapy does not eliminate the disease and immunomodulating therapy is often helpful in improving lesions. Dental disease is also a likely contributing factor.

Clinical signs vary depending on the severity of the lesions. Cats may demonstrate no clinical signs; the disease is noted incidentally at the time of physical examination. Clinical abnormalities present may include drooling saliva, bad breath, pain on opening of the mouth, difficulty eating food, change in food preference from a dry to a soft diet, inappetance, and weight loss.

Diagnosis can be achieved by biopsy of the affected tissue. Affected cats should be tested for FeLV and FIV infection

Treatment involves good dental care since periodontal disease can be a major contributing factor. Antibiotics to clear or prevent secondary bacterial infection and potent antiflammatory drugs such as corticosteroids

Cats with this problem will rarely achieve total resolution of the lesions. Response to therapy is poor, and relapses are common. The goal of therapy should be the best possible control of clinical signs.

Otitis

Otitis is inflammation of the ear, otitis externa is inflammation of the outer ear canal, otitis media is inflammation of the middle ear, and otitis interna is inflammation of the inner ear.

Otitis Externa

Inflammation of the external ear canal occurs frequently in response to infection with various forms of bacteria, parasites (mites), and yeast. Foreign bodies such as grass seeds also commonly become lodged in the ear canal. The normal clinical presentation is scratching and head shaking, the ear may have a waxy or purulent discharge.

Treatment can be carried out with topical anti-inflammatories, insecticides, antibiotics or antifungal drugs as required. Most cases will be treated with a product containing a combination of drugs such as 'Surolan' or 'Otomax'.

Those cases which respond poorly to treatment should have the ears swabbed and bacterial and yeast culture carried out to identify the offending organism and allow specific tailored therapy based on the sensitivity of that organism. Sedation and flushing of the ear canal to remove debris may be appropriate in some cases.

Otitis Media and Interna

Inflammation of the middle or inner ear can produce head shaking and pawing/scratching at the ear, and occasionally a head tilt, with no obvious inflammation or discharge visible in the outer ear canal. The inflammation can also affect some of the adjacent nerves causing drooping of the lip or ear and protrusion of a membrane across the eye called the 3rd eyelid. In cases of inner ear involvement balance and coordination can be affected.

X-rays may be required to diagnose the problem since ear examination may reveal only a normal outer ear canal. Treatment with antibiotics to clear underlying infection should be instituted. Flushing of the middle ear under sedation can be carried out but does involve some risk of damage to the structures within the middle and inner ear.