Mark Hale, DVM
All Creatures Animal Clinic, Ltd.
THE ITCHY DOG
One of the most common reasons that pets visit their veterinarian is due to itching. Many disorders can cause this to occur, but there are a few that account for the vast majority of these cases. While I will not be able to go in depth about these causes here, I will try to briefly discuss some of them. Warmer weather seems to increase the incidence of some of these, so hopefully this will be a timely topic.
EXTERNAL PARASITES are by far the most common underlying cause of pruritus (itching) in dogs.
The common dog flea is the most common external parasite of dogs. Studies have shown that for every one flea found on your dog, there are nine more in the environment. One female flea can produce as many as 20,000 eggs. Fleas are present in this area year round, but can reproduce quicker in warmer weather (as quickly as 16 days). Because they can reproduce so quickly, it is important to treat pets all year with a safe effective insecticide, preferably one that kills the egg, larvae as well as adult stages. Dogs can become so sensitized to flea saliva that just one bite can initiate a severe allergic skin condition. Treating the environment is instrumental in their control.
Ticks are a close second to the flea. Ticks can cause local irritation, more widespread allergic reactions, and can transmit serious diseases such as Ehrlichiosis, Lymes, and Rocky Mountain Spotted Fever. Keeping areas frequented by pets mowed and treated can help lower your pet's exposure. Dips, topicals, and tick collars are available to kill these ticks once they are on your pet. Read and follow all label instructions carefully as some of these can be fatal if applied to the wrong species or if ingested. (I have witnessed several cats severely poisoned by some of the "bargain" products, so be especially careful with these.) Our office will be able to recommend safe, effective products specifically formulated for your pet.
Sarcoptic mange is caused by a mite that can be transmitted from one dog to another. It can also produce bites and itching on exposed family members. This mite causes a sudden onset of severe itching as it burrows into the skin. Common areas affected include the chest, legs, abdomen, and ears. This mite lives deeply within the skin so it can be hard to find for a diagnosis.
Cheyletiella mites can cause intense itching and hair loss. This mite is more common in puppies. The scaling that it produces appears to be in motion giving it the nickname "walking dandruff." This mite can also temporarily infect people.
Demodectic mange, or demodicosis, is not considered to be contagious. This mite usually affects puppies due to their immature immune system. It can require long-term treatment to eliminate completely. Relapses or cases in older animals often point to an underlying problem with the immune system.
All three of these mites are diagnosed by a method called "skin scraping" where a scalpel blade is used to "scrape" the outer layers of skin. This sample is then examined under a microscope where the mites can be identified. Each mite requires a different treatment, so proper identification is a must.
DOGS CAN ALSO HAVE ALLERGIC SKIN DISEASES from food allergies, contact allergies, or inhaled allergies. Finding the cause (or causes) of these individual hypersentivities can take some time. Diagnosing food allergies, for instance, can take a food elimination trial of eight to sixteen weeks. This requires an exclusive hypoallergenic diet be fed with no exposure to any previous ingredients. Simply changing food brands or types seldom benefits food allergies since most commercial foods contain similar ingredients.
THE LAST CLASS OF PRURITIC SKIN DISEASES COMMONLY SEEN IS DUE TO BACTERIAL INFECTIONS. These are called pyoderma and often occur secondarily to another disease. These bacterial infections can cause intense scratching and sometimes become severe almost overnight. Antibiotics are used to control these skin infections, but if the underlying cause is not identified and addressed, the infection most likely will soon return. Often a mild allergy will not even be noticed until it weakens the skin to the point a pyoderma develops. Certain yeasts can also be involved (especially in the skin of the ears), so antifungal medications are sometimes also necessary.
Keeping your pet clean and properly groomed, using effective flea and tick control, and feeding a good quality diet can help prevent many of these undesirable conditions. If your pet begins to scratch more than normal, check it thoroughly for problems and have it examined by his or her favorite veterinarian. Early treatment can usually stop these problems before they become severe.