What is Tresaderm for Dogs?

By Shelley Moore

Produced by the animal health company Merial, Tresaderm is a medication to treat bacterial ear infections, and bacterial or fungal skin infections in dogs and cats. Tresaderm requires a prescription from a veterinarian. It comes in liquid drops and must be refrigerated.

Active Ingredients

The active ingredients are thiabendazole, neomycin sulfate and dexamethasone. Thiabendazole is a fungicide and also kills certain parasites. Neomycin sulfate is a broad-spectrum antibiotic and kills a wide range of bacteria. Dexamethasone is a synthetic adrenocorticoid steroid; it is included in Tresaderm as a potent anti-inflammatory.

Infection Causes

Common causes of skin disorders in dogs include the bacteria Staphylococcus aureus, Proteus vulgaris and Pseudomonoas aeruginosa. A dog may be more susceptible to these bacteria because of a pre-existing undetected fungal skin disorder. Also, a dog with ear mites may be more susceptible to a bacterial ear infection.


The amount and frequency of Tresaderm application depends on the severity of the condition, which is determined by the veterinarian. Generally, you would moisten each skin lesion with about two to four drops twice a day, while ears may need up to 15 drops twice a day. Tresaderm should be used only for a week or less.


The ear drops cannot be applied with a cloth or applied just outside the ear. They must go into the canal. If a dog rebels, the owner may need to ask somebody to help hold the dog or wrap it in a towel for restraint (a technique commonly used with cats).


Rarely, dogs can be sensitive to neomycin and will show redness and swelling of the treated area for a day or two. Also, dexamethasone can cause rare side effects involving electrolyte and fluid imbalance. Symptoms include increased thirst and urination, vomiting or diarrhea, and weakness and lethargy.