We see a huge number of patients with atopy in the Houston area. It is a frustrating disease to treat and manage but help is available. First we’ll go over some basic information on atopy, what we can do diagnosis and then finally treatment.
Who can get atopy? Atopy can affect both dogs and cats but for the purpose of this discussion, we will be focusing on dogs. Any breed can be affected but we see a lot of atopy in Westies, French Bulldogs, Golden Retrievers, Bull Terriers, Boxers and finally Labrador Retrievers. Age of onset is usually early, around 1-3 years of age. Dogs will present for itching, chewing and rubbing and will commonly have hair loss on the ears, armpits, around the mouth, eyes and sometimes the legs as well. Most dogs will also have secondary skin infections due to all the scratching. Dogs with atopy respond to steroids but unless the underlying infection is cleared, they may continue to itch. It’s important to realize that atopy is a diagnosis of exclusion which means all other causes of itch must be eliminated before a dog can truly be considered atopic. This brings us to our next section, how to diagnose.
What tests will my vet want to run? Skin scrapes are extremely important to rule out an itch secondary to mites. There are two common ones we worry about. The first is sarcoptic mange. Sarcoptic mange is very itchy and is also contagious to people and other pets. Demodectic mange is the second mite to consider. On its own, demodex isn’t usually itchy but a dog can itch with demodex if there is a secondary skin infection. Skin cytology is also a very important tool to help your vet know if either bacteria, yeast or both are colonizing the skin. When fleas and mites have been excluded and your vet is strongly considering atopy as a possibility, the next step is to do a food trial in order to rule out a food allergy. As a side note, we see a large number of dogs with allergies that are eating Beneful and Alpo. Even if we are not at the point of doing a food trial, we always recommend pets be switched to a higher quality food.
How to do a proper food trial: First of all, every member of the family must commit 100% to doing the food trial. If everyone isn’t on board, it will fail. A food trial is best performed with a hypoallergenic diet and the food trial can last anywhere from 4-16 weeks. These are prescription-only foods that are specifically formulated to be hypoallergenic. It is impossible to conduct a food trial with any over-the-counter food. One of the reasons is due to the fact that dog food manufacturers, even high quality ones, cannot completely clean the machines between each batch of food. This means that cross contamination between protein sources will happen and can cause an allergic reaction. Once it is determined that your pet has an allergy food, a food challenge can be conducted to determine what your pet can eat. The other alternatives are to continue feeding the hypoallergenic food or consider having a homemade diet formulated by a veterinary nutritionist.
Common pitfalls when doing a food trial:
1) Pet getting into garbage.
2) Family members feeding something other than special food (Especially toddlers and babies dropping food).
3) Giving any flavored medications or supplements including heartworm preventative. We recommend Advantage Multi for heartworms in dogs undergoing a food trial which can be ordered through VetSource on our website.
4) Pet eating feces of another pet eating different food.
5) Pet eating other pets food.
6) Giving treats (We recommend giving dry kibble as a treat or slices of baked canned food in the hypoallergenic diet being fed).
A word about blood tests for food allergies: These test are not accurate and not reliable. Frankly, they are a waste of owner’s money and can actually muddy the waters concerning what owners perceive their dog is allergic to. The only way to determine what your dog is allergic to is to perform a STRICT food allergy trial followed by a challenge diet.
What can be done to help your pet? Assuming a food allergy has been ruled out, the next step would be to allergy test your pet. This is commonly done by either a blood or skin test (sometimes both). Depending on the lab used to run the allergy test, your pet will need to be off steroids for at least 1 month prior to running the test. Once we discover what your pet is allergic to, the antigen can be given either sublingually (under the tongue) or by injection. The important thing to remember is that a response to the antigen is not typically seen until the pet has been on the medication for at least 4 months. A pet should be on the antigen for a minimum of a year before a failure to respond is considered. It is common for pets that do respond to antigen to have an occasional flare up.
Drug therapy:
1) Prednisone, Prednisolone, Temaril P (steroids): Pros-Works quickly in atopic dogs Cons: Numerous negative side effects when used chronically which is usually required in cases of atopy.
2) Cyclosporine (Atopica): Pros-If pet can tolerate medication, very few side effects. Works well for atopy. Cons-Expensive, commonly causes digestive upset, takes about a month to start working.
3) Apoquel (oclacitinib): Pros-Works quickly, few if any side effects, relatively inexpensive, can be used long term. Cons-At this writing, currently no cons to report. 2% or less of dogs had vomiting, diarrhea or lethargy which was self-limiting. Can’t be used in dogs less than 12 months.
4) Antihistamines: Not very helpful for most cases.
Apoquel is a brand new class of drug to fight itch. It’s development has been 10 years in the making. With this new drug, we now have a wonderful new alternative to steroid use.
This is a very frustrating disease for veterinarians, owners and pets. Please let us know if we can help in any way. 281-486-1509