What is My Pet Allergic To? Part 2 – FOOD

Yesterday, I saw one of my favorite patients – a super-sweet, chocolate Labrador Retriever. He had yet another ear infection and constant licking and scratching. Grandma and grandpa were over last weekend and they just can’t resist sneaking some of their dinner left-overs when those sad eyes stare longingly at them. Problem is… our sweet Labrador is allergic to chicken so now we have started the cycle of itching and infection all over again.

Today, we will discuss food allergies that cause chronic skin and ear problems. (Sensitivities to food that cause signs such as vomiting and diarrhea or conditions, such as inflammatory bowel disease, will be saved for a later post.)

So how do you know if your pet is allergic to a specific food?

If your pet has chronic skin and/or ear problems, your veterinarian will likely be suspicious of an underlying allergy. But what is your pet allergic to? First, as discussed in the previous post, make sure to rule out the possibility of a flea allergy. You don’t want to spend a lot of time, money, and energy chasing down a difficult to determine allergen, only to find that a flea allergy was the problem all along.

Next, your veterinarian may suggest a food trial to determine if there is an allergy to an ingredient in your pet’s food. This does not mean that there is a problem with the quality of your pet’s current food. It is just that your individual pet may have an allergy to one of the ingredients, such as chicken, beef, corn, wheat, etc.

Pets that have food allergies will usually be itchy year round. This is because they usually eat the same food all the time. If your pet’s problems appear to be seasonal, a food allergy is less likely, and your veterinarian may suggest skipping a food trial and going straight to addressing potential atopic dermatitis – to be discussed in the next post.

To conduct a food trial, your veterinarian will recommend a food that you must feed your pet exclusively for three months without any other food or treats given at any time. There are strict requirements that need to be met when conducting a food trial so it is best to consult with your veterinarian.  Usually, the selected food will be based on either a “novel protein” or “hydrolyzed protein”. A novel protein is one that your pet has not been exposed to before such as venison or rabbit. A hydrolyzed protein is so small that it is unlikely to cause an allergic reaction.

Food can be homemade, but there are also several commercially available pet foods. The important thing to remember is that it must be a novel protein or hydrolyzed protein and specifically designed for food trials. A food simply labeled for sensitive skin is not suitable for a food trial. Many appropriate foods will be by prescription and a bit more expensive, but it is best to do it right the first time and then after determining the specific problem ingredient, search for other options that might work for your pet.

The most important thing during a food trial is that your pet does not receive any other food or treats during the three months of the trial. Remember that once exposed to an allergen it can cause a reaction for up to 6 weeks. So if your dog is allergic to chicken and you feed a dog biscuit treat or rawhide with chicken flavoring, your dog will react for up to six weeks and you are back to square one. Also watch out for any flavored products such as medications (heartworm pills are commonly flavored) and toothpaste that may contain the food allergen.

If your pet has successfully completed a food trial and their allergy signs have resolved, it is assumed that they have a food allergy, but the specific allergy is still not yet identified. At this point, different food ingredients can be introduced one at a time for a week’s duration, and the animal observed for any recurrence of signs. For example, you may feed your pet chicken for 1 week. Then stop feeding chicken and just feed the food trial food for 1 week. If itching, skin, or ear problems develop, it is assumed that your pet has a chicken allergy. If not, chicken is allowed and you go on to test the next possible ingredient.

If your pet’s allergic signs never resolved with the food trial, then it is assumed that it is not a food allergy and we progress to the next step in allergy identification which we will discuss in the next post – What is My Pet Allergic To? Part 3 – Atopic Dermatitis.


What is My Pet Allergic To? Part 1 – FLEAS!

Fleas are itchy and annoying for all pets, but for a pet that is flea allergic, fleas can be intensely itchy and cause secondary skin infections. Yesterday, I saw a cat that was so itchy from her flea allergies that every time you pet her she would uncontrollably chatter and bite at the air or obsessively lick herself. She was just miserable!

Believe it or not, if your pet has allergies, you might hope that the allergy is to fleas rather than some other allergen. This is because compared to most types of allergies, you are more likely to be able to identify and possibly eliminate fleas. However, this does not necessarily mean that it will be easy!

What are the Signs of a Flea Allergy in Dogs and Cats?

Signs of a flea allergy include itching, scratching, licking, hairloss, and/or skin infections. Signs may be concentrated on the lower back, tail, and rear legs, but not necessarily. Cats will frequently get a condition known as miliary dermatitis which appears as many, small, crusty bumps on the skin. Keep in mind that the presence of these signs does not definitively diagnose a flea allergy, but are commonly seen with the condition.

But I Don’t See Fleas…

Often, when I ask an owner, they are confident they have never seen fleas. This is actually not unusual even when an animal has a severe flea infestation. Fleas are notoriously good at hiding. One tell-tale sign, that an animal has a flea problem, even if actual fleas have not been directly seen, is the presence of “flea dirt”. Flea dirt appears as tiny black specs within the hair coat or on the skin when the skin is combed against the grain. Flea dirt is actually flea feces or digested blood and if placed on a white towel and moistened, it will turn a red color.

What do I do to Treat Flea Allergies?

Even if there is no direct evidence of fleas, I still usually recommend taking steps to rule out the possibility of a flea allergy before delving into the often more complicated, time-consuming, and costly task of identifying other allergies. This is because the saliva from a flea bite can cause an allergic reaction for up to 6 weeks, long after the flea is dead and gone. So even if just one flea had the chance to bite, your pet could suffer the consequences for up to 6 weeks.

No flea product is a magic bubble that prevents fleas from biting if the animal is in a flea infested environment so keep this in mind when assessing your pet’s risk to flea exposure. Do you take your pet to the dog park regularly? Do you have stray cats that frequent your yard? These are questions to ask yourself when considering the possibility of potential flea exposure.

My first recommendation is usually to ensure adequate flea control by treating the affected animal, all animals in the household, the house itself, and the yard, as well as avoiding situations in which your pet may come in contact with fleas. Always use flea control products that are safe and effective for your pet. (We will discuss this in more detail in a later post.) If you can ensure that there is no chance of flea exposure for two months, there are no signs of infection, and your dog or cat is still itchy, we usually assume that flea allergy is not the primary problem. Always consult with your veterinarian about your pet’s specific medical conditions and treatment recommendations.

Does My Pet Have An Allergy?

Allergies are itchy, but they are also the most common cause of chronic and recurrent skin and ear infections. Every day, I see several patients with itching, allergies, and related medical conditions. If your dog gets skin or ear infections several times a year, it is very likely that your pet has an underlying allergy. Resolution of these problems cannot be fully accomplished until the underlying allergy is addressed.

Allergies are notoriously frustrating. Most owners should be prepared to deal with them to some extent for the rest of their pet’s life. However, this does not mean you have to resign yourself to constant scratching and licking, infections, or frequent and expensive visits to your veterinarian. You may have to work closely with your veterinarian initially, but once the allergy is identified, it is generally easier to manage them.

Allergies can be classified into three broad categories:

  • Fleas – Fleas are itchy for all animals, but pets that are allergic to fleas will be extremely itchy and frequently lose their hair and develop skin infections.
  • Food – Your pet may be allergic to an ingredient in the food they are eating. This does not mean that the food is not a quality food. Your dog may just have an allergy to an ingredient, much like a person would have an allergy to specific foods.
  • Atopic Dermatitis – This includes environmental allergens, such as dust, pollen, grass, etc.

Exposure to an allergen can cause an allergic reaction for up to six weeks. Ideally, the allergen causing your dog’s itching is identified and avoided. However, often times this is not possible. Either identification of the allergen is difficult or avoiding the allergen is impossible. My next posts will discuss the steps to take to determine which allergen is triggering your dog’s flare-ups, how to treat them, and what options are available if a specific allergen cannot be identified or avoided.

Why is my pet itchy?

Itching, also known as pruritus, is one of the most common presenting complaints I get from pet owners. They are frustrated listening to the incessant scratching and licking which may keep both them and their pet awake at night, and concerned that their dog or cat is uncomfortable.

Itching is a non-specific sign, meaning that there can be many different causes. However, most cases of itching can be attributed to two broad categories: infections and/or allergies. Often times, both infection and allergies may be contributing to the problem. A pet with allergies is more susceptible to secondary infections. Both are itchy and create a cycle of itching, licking, and infection.

The first step to relieving itchiness in your pet is to identify the cause. Your veterinarian will usually start by asking some relevant questions about your dog or cat, other pets and people in your household. Questions will include detailed information about the type and duration of signs and past and current medications.

Your veterinarian will perform a physical examination of your pet to determine if there are any signs of infection, such as hairloss, redness, pustules, crusts, etc. Infections can be bacterial, fungal (yeast and ringworm), or parasitic (demodex and sarcoptic mange). Diagnostic tests, such as skin cytology, fungal culture, or skin scrape, may be performed. If infection is present, it must be treated in order to determine if it is the primary cause of itching or if it is secondary to allergies or another cause.

Allergies are extremely common and are likely the cause of most cases of itchy dogs. My next posts will discuss allergies and how to treat them.