Since we are in South Georgia, I thought this would be a great blog topic. I would guess 70% (or more) of the cases we see are itchy pets. The clinical signs can be mild to severe and range from licking paws to scratching until hair falls out. These pets can be absolutely miserable and often make the owners miserable as well.
So why is my pet itchy? The one single reason most pets are itchy is something called Atopic Dermatitis. Simply put it means itchy skin and is usually due to environmental allergies. It is important to understand that environmental allergies are different than food allergies. Food allergies are much less often the culprit so I will discuss them briefly later on. Environmental allergens can be anything that the pet is exposed to, from pollen to fleas.
Flea allergies are one of the most common and severe presentations of itchy dogs and cats. Pets with flea allergies become itchy when they are bitten. Just like in people some animals are more allergic than others and as little as one bite can cause a reaction. Some pets have such a severe allergy that the owner and vet may not see fleas, but due to the presentation, flea allergy is still determined to be the cause. These pets can even be on a flea preventative and still have a break-out if bitten.
Other environmental allergens can be much more difficult to pinpoint because they can literally be anything in the pets environment. Some dogs may have an itchy belly and feet after being exposed to grass. Others may suffer from pollen. I have even seen cases where certain carpet cleaners and laundry detergents have caused reactions.
Food allergies, while much less common, do also exist. Food allergies are almost impossible to test for with a standard allergy test in an animal hospital. The most common way of diagnosing food allergies is by trial and error. The pet is usually treated for an environmental allergy and if traditional treatments fail, food allergies start to be suspected. Another sign may be loose stool or nausea, however, this is not always the case and not reliable alone to make a diagnosis.
So what can I do?
For environmental allergies or atopic dermatitis, there are several options for treating this disease. Since fleas are commonly associated with allergies and itchy pets in this region, flea prevention is the most important part of management. A monthly flea preventative is the most effective way to control fleas.
Next, these pets have a weakened skin barrier, which makes them more susceptible to allergies. Normal dogs have healthy skin which protects them form this disease. In allergic dogs the skin barrier is defective and allows the allergen to penetrate and cause itch.
This is why my first step in treating this disease is to start a prescription diet like Hill's Derm Defense. This food, and others like it, have been proven to improve the skin barrier and make it less susceptible to the allergens in the environment. Sometimes this diet alone can control allergies.
If diet alone is not enough, the actual itch can be addressed. There are a range of products from steroids to pills (Apoquel) and injections (Cytopoint) that can help control the itch.
Finally, in severe cases of chronic itch, the pet will often have a skin infection. This is a part of the itch cycle that i will describe in just a second. The pet essentially scratches so much that the skin is completely broken and bacteria creates an infection. These pets will need antibiotics as a part of their treatment.
Finally, managing food allergies. If the above treatments were unsuccessful, or food allergies have been diagnosed due to other history and clinical signs, your pet may need a food trial. This means your pet will have to eat a specific food for a period of time and can not be exposed to any other treats or food during this time. It is very important to realize that protein is almost always the source of a food allergy. Although it is a popular trend right now, grains are almost never the source of an allergy. If the pet remains free of clinical signs during the food trial, different proteins can be reintroduced to determine the source, or the pet remains on the special diet to avoid reactions.
The itch cycle and where each treatment fits
I briefly mentioned the itch cycle earlier. This will be a layman's explanation and a more scientific definition can be found here.
As mentioned earlier, most of these pets have a defective skin barrier (this is why the food, Derm Defense, helps). Allergens are able to enter the skin and cause the body to have a reaction. Remember these can be anything from fleas to pollen. Once the skin has been breached and the reaction occurs, cells see the allergen and release components that tell the pet, "you are itchy". Apoquel and Cytopoint help limit these symptoms. Once the pet receives that message, it begins to scratch. As the pet scratches the skin barrier becomes even weaker and more allergens can breach it. Now more signals are sent to tell the pet, "you are itchy". Now the pet scratches, licks or chews more. This leads to more broken skin, more allergen, more itch and eventually infection. This is why we often call atopic dermatitis a viscious cycle. This is also why once started, it can be so hard to gain control.
Every veterinarian may differ in their means of approaching these cases and every pet's needs will vary. As a simple rule, my goal for control in an itchy dog is to try to stop the itch at each step of the cycle. This means fix the weak skin barrier with food, control the itch with medication as needed, and finally treat any skin infections that may be present.