1. Why does my pet need such a high dose of antibiotics for such a long time to treat his skin infection?

Most pets, especially dogs, with skin infections have what is called bacterial folliculitis, meaning the bacteria have colonized the hair follicles. This is in contrast to the classic "hotspot" a flea-allergic dog may create after an hour of scratching its rump, where the infection is usually very superficial. One of the most important reasons topical therapy alone is not adequate for pets with bacterial folliculitis is because their infections aren't entirely on the skin surface.

For a pet with a standard bacterial folliculitis, at least three weeks of antibiotics are needed, and the general rule is to treat until the pet's clinical signs have been resolved for one week.

Allergies, whether they are due to fleas, food, or environmental agents, are caused by the immune system overreacting, NOT a weakened immune system, a common client misconception. Studies have shown that animals with flea allergic dermatitis cannot be desensitized for fleas, so the only treatment is avoidance. The same is true of animals with food allergies.

Animals with environmental allergies, or atopic dermatitis, can be desensitized to what they are allergic to through the use of allergen-specific immunotherapy. Immunotherapy "retrains" the body's immune system, but, even when it works, animals usually require it for the rest of their lives to control the disease. In extremely rare cases and usually after years of therapy, immunotherapy can switch the body's immune response, and the animal no longer needs to be treated.

3. Is my pet's condition contagious?

Both canine and feline sarcoptes mites--canine Sarcoptes scabiei and feline Notoedres cati--can cause lesions in people. The canine Demodex mites are not contagious to people, but Cheyletiella mites can be. Some dermatophyte infections are transmissible to people, with the most common being Microsporum canis.

4. How do I decontaminate my environment while treating my pet for ringworm?

The environment should be addressed in every case of dermatophytosis. This is most important in cases of M. canis infection, since the spores can live in the environment for up to 18 months.

Clients should vacuum, disinfect, and steam clean the affected environment and discard infected bedding. Specifically, they should thoroughly vacuum and disinfect all nonporous surfaces, including floors, walls, countertops, windowsills, and transport vehicles. The cleaner of choice is bleach at a 1:10 dilution (13 oz/gallon). Advise clients to clean a test area to make sure the bleach won't damage the surface. Undiluted bleach cannot be used safely in homes or catteries as it is corrosive and irritating.

If possible, clients should destroy all contact bedding, rugs, brushes, combs, toys, etc. Rugs that cannot be destroyed or removed should be washed with an antifungal disinfectant, such as bleach or chlorhexidine. Advise clients to test the colorfastness of items before using these agents.

Steam cleaning carpets is recommended to kill spores; the temperature of water forced into the carpets must be at least 110 F. For this reason, recommend that clients use a professional steam cleaner because rental machines do not reach high enough temperatures. Also, recommend that clients vacuum and disinfect all their heating and cooling vents.

5. How do I perform a proper food trial?

Currently, there's no accurate blood or skin test that can diagnose whether a pet has a food allergy. The only way a veterinarian can make a diagnosis is to change the pet's food to an appropriate elimination food-trial diet for eight to 12 weeks. This is done by feeding an elimination diet containing an unusual protein and carbohydrate source that the pet hasn't been exposed to, or by feeding a diet in which the proteins are hydrolyzed (made smaller) so the immune system won't recognize them. During this eight- to 12-week period, the food-trial diet must be fed without the addition of table scraps, treats, or chewable supplements, including flavored heartworm preventives. The only way to successfully perform a food trial is for clients to be strict about what the pet is allowed to eat.

The reason the trial must last so long is that some pets won't show improvement until up to three months after being off their original food. It is always recommended to gradually switch to the new diet during a three- to five-day period. Fresh water should never be withheld and always available free choice. The veterinarian in charge of the case will determine if treats are allowed and, if so, which ones.