Understanding Cat and Dog Allergies, and What You Can Do to Help Your Pet

One of the most frustrating conditions for pet owners is having an itchy pet.

There is nothing more simultaneously exasperating and heartbreaking than having an animal that is constantly licking, chewing, and scratching. On top of that, chronic ear and skin infections secondary to allergies lead to foul odors, further discomfort, and costly veterinary bills.

The key to solving these issues lies not only in treating the secondary conditions but in getting to the root of what is happening in the pet’s body to allow them to occur.

Here are some ways to figure out if the itching and scratching are because of your cat or dog’s allergies, and if so, how you can help them.

Allergy-Related Symptoms

For pets, there are 10 very common symptoms of allergic skin disease that you can look out for.

  • Chronic ear infections
  • Licking of feet/other areas of body
  • Odor of yeasty bread
  • Fishy smelling odor
  • Redness of skin
  • Yellow exudate on skin
  • Open sores or scabs on skin
  • Scratching often
  • Shaking head and scratching at ears often
  • Thin and/or greasy feeling haircoat

If you notice any one or more of these symptoms on your pet, it’s best to contact your vet and schedule a visit as soon as possible.

What Your Vet Wants to Know

Any examination by one of our mobile vets that involves a complaint about a pet’s skin or ears begins with what may to some like an endless list of questions. Each of these history questions helps your veterinarian drill down to the cause of your pet’s symptoms.

To get to the origins of the current symptoms your vet must have a clear picture of what you are seeing, when you are seeing it, how any previous treatments have or have not worked, and where you feel your cat or dog is currently in his severity.

The great news is that we have compiled a “quiz” of sorts below to walk you through the questions we usually ask during one of our mobile vet visits. If you ever need to have your pet examined by us for a skin irritation, you can think about how you’ll answer these questions beforehand and give thorough answers so that we can recommend the best solution to this historically discouraging problem.

  • Do your pet’s symptoms occur seasonally?
  • Do your pet’s symptoms occur year-round?
  • Is your pet on flea control?
  • Does your pet keep you up at night scratching or licking?
  • Has your pet had more than 2 ear infections within a year?
  • Does your pet lick any part of its body incessantly?
  • Does your pet chew at his/her feet?
  • Does your pet have a yeasty or fishy odor?
  • Is there any yellow flaky or gooey material on your pet’s skin?
  • Does your pet have open sores or scans on his/her skin?
  • Does your pet scratch his/her ears and cry?
  • Does your pet shake his/her head often?
  • Have you changed your pet’s food recently?
  • Has your pet ever been treated successfully with a steroid type medication (examples: Prednisone, “anti-itch” shot, triamcinolone, dexamethasone)?
  • Has your pet ever had raised welts on his/her skin?

Types of Cat and Dog Allergies

Once it has been determined that your pet is likely suffering from allergic skin disease, the search begins for the root cause.

Cat and dog allergies can be generally categorized into two types: food based and environmental. It is always ideal if we can manage the allergies from the underlying cause as much as possible, although sometimes it becomes impossible to determine the specific allergen.

It is important to note that we believe that allergies are cumulative in their effect on a patient’s immune system. For example, if a pet is allergic to the chicken in their diet, they have fleas, and they are exposed to an environmental allergen such as a pollen, they begin to have a reaction. The combination of all of those stimuli lead to symptoms when only one or two of those on their own may not have caused such.

For this reason, we always talk to clients about an analysis of an allergic pet’s diet, even if the cat or dog’s allergies are seasonal in nature and they do not exhibit some of the classic distribution of lesions for food allergy.

Food Allergies and Treatments

Some pets can be allergic to proteins from the ingredients in their foods. Pets can also develop allergies to food over time, so just because a pet begins having problems later in life and has been on the same food, it does not mean that food may not play a role in the symptoms.

Despite what the very effective marketing campaigns of pet food companies have convinced most pet owners, grain-free food is in no way hypoallergenic. A pet can be allergic to potato protein just as easily as to a protein found in corn.

Pets are often allergic to the meat source of protein as well. There are some protein sources that are purported to be more highly allergenic, such as chicken, but there is little reliable data to back this up.

So how do we determine what a pet may be allergic to in their food? There are several ways, some more practical than others, depending on the pet and the dedication of their owner to the process.

Elimination Diets

The first way we can test for food allergies is an elimination diet. The pet is put on a very restricted diet with only one or two protein sources that they have never eaten before for at least 16 weeks. If symptoms subside during that time, then a food allergy is the suspected cause and the owner can slowly start adding in other proteins and watch for symptoms to return.

The pros to this process are it is inexpensive for the owner and effects a change in symptoms in a short amount of time. The cons are that it may be difficult to assess response to treatment if there are multiple sources of allergic response for the pet as discussed above. It is also a very difficult thing for owners to stick to and can be extremely hard to effect in homes with multiple pets or small children (think how often the dog sneaks into the cat’s food dish or scoops up a toddler’s abandoned Cheerios).

Hydrolyzed Protein Diets

The second way we can test for food allergies (and simultaneously treat them) is by putting the pet on a hydrolyzed protein diet. These diets have had the proteins contained in them broken down into smaller molecules that have nutritional value but do not cause the same immune reaction in the body. In this way, they become somewhat “hypoallergenic.” These diets do not eliminate all allergenic proteins so a negative result to changing to one of these diets cannot completely rule out food allergy.

The pros to this method are that it tends to be ultra-convenient for the client as these diets are made in kibble form and are readily available from veterinary offices, or pharmacy websites. If an owner has multiple pets, these complete diets are often appropriate for all the dogs or cats in the household (species-specific) so the logistics of keeping one animal away from a potentially allergenic food become much easier.

The first major con to a diet like this tends to be the cost! They can be very expensive to maintain, especially for a larger dog. They also tend to be less palatable for pets since they do not have the fully formed proteins in them. These diets are also readily digestible since the proteins are already partially broken down and this can cause pets who are prone to obesity even more vulnerable to staying overweight.

Novel Protein Diets

A third option to manage food allergies is a novel protein diet. This means that a protein the animal has never eaten before is identified (like buffalo, venison, or duck) and the pet is switched to a pet food that contains this protein.

The pro to this method is its ease of implementation and relatively low cost. However, it can have major holes in its accuracy; although you may have changed the source of the main meat product in the food, the pet may be allergic to milk or soy and these ingredients may still be present.

There are blood testing methods that can help us to get around this problem. These blood tests search for antibodies within the bloodstream to a myriad of foods and report those that are present. We can then use this list to choose which protein sources to avoid and which novel protein diet to begin.

There is some controversy surrounding this method as there may be false positives to the test (ie: there may be circulating antibodies in the bloodstream for beef, but the animal is not actually having a clinical reaction to beef). One argument to employ here is that as long as you follow the list and keep your pet away from the foods they are allergic to if you happen to keep them away from a few that they aren’t, then so be it—no harm is done.

With any of the diet change options above it is extremely important that all food, treats, medication and even toys are analyzed to be sure they do not contain an ingredient that may perpetuate the problem.

For example, if your dog is allergic to beef and you change his food to a duck-based diet but continue to give him beef rawhide bones or treats that contain beef, then you are negating all the good work you are doing with the main diet.

The necessary duration of these trials is also extremely important. It is recommended that any food trial is done for 16 weeks to truly determine if it is effective.

Parasitic Infection Allergies

Parasitic infections must also be addressed when confronting any skin issues in pets. The most common infestation is fleas. Fleas may cause little to no skin reaction in one patient, while another will have major dermatitis from just a few flea bites.

Whenever we are dealing with an allergic skin disease in an animal, we are always going to recommend monthly flea control to rule out parasites as a potential underlying cause for the reaction. If a skin condition can be cleared up simply by putting a pet on flea control it will save money and prevent unnecessary medications. The investment in a good flea control product will save money in the long run.

There are many common myths about fleas that we encounter far too often when discussing them with pet owners. Here are the main flea myths we hear, and what the truth behind them actually is.

  • Fleas are only present in the summer or cannot attack a pet when it is cold outside – False! Your home never falls below freezing, so even if fleas are dormant outside, they are still able to thrive in a climate-controlled home.
  • Flea prevention products harm pets – Although there are sometimes mild side effects to some flea products, veterinary recommended products are exceedingly safe. The potential health hazards of a flea infestation far outweigh the likelihood of a significant reaction to a control product
  • I don’t see any fleas, so we don’t have them – Fleas can be exceedingly hard to see and can often be groomed off by a pet before they are noticed. Just because you have not visually detected them does not mean an allergic pet should be left unprotected.
  • I have 3 pets, but I only need to treat the one with the skin problem – Also false! All pets in a household must be treated with a preventative method otherwise they will serve as a reservoir for the fleas to continue to live in the environment.
  • I gave my pet flea control two weeks ago and now I am seeing fleas again, clearly it isn’t working – It’s hard to see your pet itching and suffering, so not seeing immediate results can be discouraging. But it takes up to three months of consistent treatment, as well as active cleanup of your pet’s environment, to get to a 99% reduction in flea population numbers. This has to do with the lifecycle of the eggs and immature stages that are already in the environment.

If you suspect your pet has fleas, you should contact your vet for an examination as soon as possible. Vets can confirm or deny the fleas and give you our recommendation for a solution, whatever the cause of irritation.

Environmental Allergies and Treatments

Once these two primary causes are addressed, we turn to attempting to control environmental allergens.

However, keeping pets away from common environmental pathogens such as grass, dust mites, and plant pollens can prove impossible. This is when we must consider either trying to desensitize a pet to the allergens or give them a medication that mitigates the reaction they are having to them.


Desensitizing your cat or dog to their allergens requires first identifying what the pet is allergic to and then slowly exposing them to very tiny but increasing amounts of that allergen via allergy injections or oral administration. The initial allergy testing can be done via either a skin or blood test.

Once the offending allergens are identified, a customized allergy serum is produced for that animal in progressively more potent formulas in hopes of slowly getting the body used to exposure to the allergen. Pets often require once monthly maintenance therapy for life after an initial treatment period of 8-12 months. This method is as close to a cure as we can get for an allergic disease but is often very difficult for owners to stick with and comes with a significant up-front cost.

If a pet cannot be desensitized to the allergens, then we must find a way to control the symptoms of the allergies utilizing medications. There are several common medications and often pets must have a combination of treatments to keep their allergies well managed.


The efficacy of antihistamines in pets is questionable, but anecdotally some animals seem to respond to these medications. They also have few side effects and are relatively inexpensive, which makes them an attractive choice for pet owners.

The general rule of thumb is to try each antihistamine for at least two weeks before determining if it is helpful or not.


Steroid medications are extremely effective in managing the symptoms of cat or dog allergies. They are very safe when used judiciously and for short time frames. Steroids do have unwanted side effects in the short term, such as increased thirst and urination, but these are dose-dependent.

Steroids often get a bad reputation because they are used inappropriately or for long periods of time which can cause long-term side effects. They also interact with some other common medications, so always make sure your veterinarian knows all the medications your pet is taking and do not administer any new ones until you notify them.

Steroid medications are very inexpensive and combined with their efficacy they are the usual first choice in itchy animals. Sometimes a short course of therapy or injection of one of these medications is all that is needed to get through a season or buy some time for a food change. If an animal responds but relapses continually then it is appropriate to start looking at other medications that are safer long-term to manage the symptoms.

Alternatives to Steroids

Apoquel is a relatively new medication that has helped veterinarians drastically improve the lives of many allergic animals. It is very effective in controlling symptoms and the side effects seem to be relatively rare. Animals tolerate the medication well and owners report drastic differences in skin health.

The major downside to Apoquel is its relative cost compared to other medications. However, we always discuss with owners the overall cost of continuous veterinary visits to treat an unmanaged allergy patient in comparison to the monthly cost of the medication.

Apoquel can be used year-round or seasonally depending on the animals’ needs. Currently, Apoquel is only licensed for use in dogs.

Atopica (cyclosporine) has been available as an alternative to steroids for many years. Atopica is an immune modulating drug that quiets the immune response that is occurring in the allergic patient. It can be very effective in some animals.

The major side effect that keeps some patients from being able to take this medication is vomiting. This medication is also relatively expensive and must be continued long-term, or at least through the offending season.

Secondary Infections

Many perceived treatment failures related to medications designed to control allergic symptoms happen because of concurrent secondary infections that are not adequately addressed.

When the skin is compromised due to the inflammation present from allergic disease and/or the animal is continually traumatizing the skin, the normal bacteria and fungi that live there can cause an infection. The two most common skin infections associated with allergies are a staph infection and yeast infections.

It is imperative that these infections are cleared in conjunction with any medications that are given to control the allergies. These therapies can last between one week and several months, depending on what is being treated. They may include oral antibiotics and antifungals as well as topical ointments, sprays, or shampoos.

If your veterinarian recommends treatments for secondary infection, please be sure to heed their advice. Failure to treat will often result in chronic or resistant infections in the future and extended discomfort for the pet.

Getting Help with Cat and Dog Allergies

Cat and dog allergies are a major concern and can have lasting effects on a pet’s quality of life and overall health.

If you think your pet is suffering from allergies please call Vet’s Here today at 1-888-838-2738 to both assess your pet and their environment so you and your pet can get some relief from the itching, scratching, and licking!

Schedule your mobile vet visit

Call Now ButtonCall Now Skip to content