The cat is very likely to have inflammation of the ear canal, and the color of the ear wax could be an inflammation caused by an ear parasite called Otodectes cynotis, which lives and parasitizes in the dogs and cats ear canals. By persistently combing and shaking the head, the cat can do additional damage, such as hairless spots around the ear itself, the wound, the hematoma of the ear.
A visit to the vet is necessary to make an accurate diagnosis. The diagnosis is made by examination of ear canal and microscopic examination of ear wax.
Otodectes cynotis are easily transmitted from animal to animal. Therefore, if you have any other pets, inspect them to prevent possible transmission. Dogs are most commonly infested through cats, and although extremely rare, parasites can also spread to humans.
Cynotis although it will generally feed within the external ear canal, its feeding activity is not confined to the ear. It can be found on the skin adjacent to the ear. Also. they can “travel” all over the body.
Therapy for Otodectes infestation may be topical and/or systemic. Topical cleaners play an important part in any therapeutic regime. The use of a mild ceruminolytic cleaner helps remove wax to facilitate better penetration of a topical miticide and also makes the animal feel more comfortable.
Ear drops that contain tiabendazole have excellent acaricidal activity against all stages of the mite life cycle – offer a good topical option for therapy. Many of the licensed topical ear drops do not contain a specific miticide and are thought by some authorities to work by “smothering” the mites, as most contain an “oily” type of base such as propylene glycol, liquid paraffin or sesame oil. This may be reflected in the fact administration of these products suggests once or twice daily application for up to three weeks. The presence of a topical glucocorticoid in ear drops helps to reduce swelling and inflammation within the ear and aids in the treatment of any hypersensitivity reaction.
Topical therapy does not address the possibility of ectopic infestation with mites at sites distant from the ears. Lesions at these areas are best treated by the use of systemic medication. Many of the spot-on or spray-on flea preparations can be used for this purpose. Where a prolonged course of topical therapy to resolve otic infestation is not possible systemic medication may be the only way the animal can be treated.
Avermectins form the mainstay of systemic therapy when both otic and ectopic disease is to be managed. Although such drugs as ivermectin can be used off licence, there is little indication to use these with the availability of safer licensed preparations. Moxidectin and selamectin are available as licensed topical spot-on preparation in both dogs and cats. Moxidectin has been shown to be 99.6% effective in the therapy of Otodectes in cats when two treatments are applied at 30-day intervals. In dogs, similarly high efficacy rates of 98% have been reported when moxidectin has been used topically twice at 28-day intervals (Bayer studies). Selamectin has demonstrated a 100% efficacy when used to treat O cynotis in cats and dogs.
The manufacturer’s recommendation is a single treatment in cats and two applications at a 30-day interval in dogs.