Everything You Wanted to Know About Pets and Allergies 2020 Edition
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Everything You Wanted to Know About Pets and Allergies 2020 Edition This article is a gathering of information and experiences I have gained over the years of clinical practice. Your veterinarian’s experiences and opinions may differ than my own. –Dr. Amy Walton Allergies are extremely common in dogs and cats. When we think of allergies, we usually think about runny noses, itchy eyes, congestion, and sneezing. While some of our pets may display signs of upper respiratory inflammation, this is actually an uncommon presentation of allergies. Both environmental and food allergies often manifest as skin disease! In this article, we will be discussing how allergies affect our pets, clinical presentations, diagnosis, and treatment options. Environmental (Inhalant) Allergies Environmental allergies typically manifest as signs of “hay fever.” These allergens in people typically manifest as runny nose and itchy eyes but in our pets they penetrate the skin barrier leading to a reaction at that location. Symptoms of allergies include licking feet/limbs, shaking the head, recurrent ear infections, itchy backs, and sometimes licking around the bottom. Redness can often be found on the feet, belly, ears, mouth, and anus. Depending on the severity, it may be present in only one or two of these locations. Some pets do experience sniffling, sneezing, reverse sneezing, ocular discharge, and increases in upper respiratory noise. If you observe these, your pet still may have allergies and should see their veterinarian. Symptoms may be seasonal or yearlong which is referred to as atopy. Allergies often appear in a typical pattern but may be variable depending on the severity of the disease. Some dogs and cats may only have recurrent ear infections as a sign of allergies!
Cats are slightly different. In cats, allergies often result in itching around the head and neck region. However more severely affected cats may experience overgrooming to where hair loss is observed along the limbs, belly, tail, and even up the sides of the body! Allergies can also present in other strange ways such as “rodent ulcers” or eosinophilic granuloma complexes. Asthma in cats is also a true allergic-type reaction and must be managed as such (and is a life long condition). Scabs and redness in temporal regions. Generalized. Often referred to as fur mowing. 1 2 1. Rodent Ulcers- may also present on tongue or elsewhere in mouth. 2. Eosinophilic granuloma. These often present on the belly but may be seen elsewhere on the body.
Food Allergies
Food allergies are actually quite uncommon, if not rare. It appears similar to environmental
allergies and most commonly manifests as skin inflammation. While environmental allergies
often start when the animal is young (> 1 year of age), most animals with food allergies do not
show clinical signs until they are over 5-6 years old. In fact, these animals have usually eaten
the same food their entire lives with no issue. Sometimes food allergies will also present in very
young animals less than 6 months of age. Remember that these are general statistics and your
pet could still have food allergies diagnosed at 2-3 years of age.
A few other unique characteristics:
• The problem usually occurs year long. NOTE: Pets with Atopy (environmental allergies)
that are reactive to indoor allergens (example: dust mites) often have year long allergies
as well. Atopy is more common than food allergies.
• No response to treatment for sarcoptic mange. Note: Sarcoptic mange can be difficult to
diagnose so often we treat if it is suspected regardless of test results.
• Little to no response to environmental allergy control drugs such a steroids, Apoquel®,
etc. We’ll discuss therapy options later in this article.
• Itching and skin inflammation may be more concentrated around the anal area. Often
these animals may be mistaken for having chronic anal gland issues even when no
problems are found when expressed. This does not rule out environmental allergies;
however, in my experience pets with food allergies often seem to have more issues
around their anal region.
Food allergies can also manifest in other unique manners besides skin inflammation. These
include:
• Gastrointestinal tract disturbances- vomiting, diarrhea, poor appetite.
• Poor doer- Difficultly gaining weight, rough hair coat.
• Seizure activity- NOTE Food allergies are quite uncommon and it is even more rare for it
to present in this manner. If your pet has seizures, it should be worked up and managed
for common causes and not initially with a dietary trial.
Owners often assume that food allergies are caused by grains. This is the result of heavy
marketing from pet food companies that have NO scientific evidence that grain free is “better.”
This will not be discussed in this article but I encourage you to research scientific literature and
consult board certified veterinary nutritionists with your questions.
Food allergies are most commonly attributed to animal-based proteins such a chicken, beef,
and pork. Grains are an uncommon cause but some pets are allergic to corn, wheat, etc.
Diagnosis and treatment of food allergies will be discussed later in this article.
Flea Allergy Dermatitis
Fleas are one of the most common causes for redness
and itching! Some animals may be so sensitive to flea
saliva only 1 or 2 can incite hair loss and extreme
redness. Fleas can also make animals that have
allergies have more severe reactions. Flea allergy
dermatitis often follows a very common skin pattern in
both dogs and cats. Fleas like to bite around the tail
head area, inner thighs, and hind limbs. You will most
commonly see hair loss, redness, and itching in these
areas; however, severely affected or very sensitive
animals may display more dramatic patterns. Hot spots,
rodent ulcers, and secondary skin infections can also be
caused by fleas.
IF YOUR PET IS NOT ON A GOOD FLEA PREVENTATIVE,
FLEAS CANNOT BE RULED OUT AS A CAUSE OF YOUR
PET’S CLINICAL SIGNS. It is recommended that all pets
(including indoor only cats) be on year around monthly
flea preventatives. If allergies are suspected, it is even
more important that your pet be on a good
preventative, not only for diagnostic purposes, but also
to keep fleas from making the symptoms worse.
Note: Cats will often scratch around their head and neck with fleas,
too. You may see areas of inflammation, scabbing, and excoriation.
Contact Allergies
Contact allergies are what we typically associate with “hay fever” type symptoms. These can
happen to our pets. When a pet comes in contact with an allergen, a reaction occurs at the
point of contact. This is typically seen along the belly or thinly haired areas. Common contact
allergens are often chemicals such as lawn sprays, topical medications, fabric detergents, wool,
etc. Removing and/or washing off the offending material typically results in the resolution of
the lesion in a day or two.
Other Problems Associated with Allergies
Secondary skin infections: Inflammation associated with allergies leads to the breakdown of the
skin’s protective barrier and excessive to production of oils (sebum). Normal skin flora, such as
bacteria and yeast, often flourish unchecked. This results in pyoderma, or skin infection.
Pyoderma is inherently itchy and will make your pet
feel even more miserable. Treatment of these
conditions along with the underlying cause (allergies) is
needed to provide relief to you pet. Animals with
allergies may not always have pyoderma and animals
with pyoderma may not always have allergies.
Bacterial infections often result in rashes, papules, or
pustules. Yeast often creates a thickened almost
elephant skin appearance. Often infections are yeast
and bacterial combinations and may have a range of
appearances. Skin can also become hyperpigmented, or
darkened, due to chronic inflammation or infection
(bacterial or fungal).
Skin infections are often treated with systemic and/or
topical antibiotics and/or antifungals. This may be in
the form of oral medications, injections, and/or topical
shampoos, creams or sprays.
To make things more complicated, dogs can actually be allergic to their own normal skin
bacteria!!! It’s called Staphylococcal Hypersensitivity. These dogs are often afflicted by constant
reoccurrence of pyoderma that returns quickly after treatment is stopped. These dogs typically
require long term antibiotic therapy (systemic and topical) and may receive staphylococcal
bacterin injections. These injections are a form of desensitization therapy. This treatment may
not always be successful and the pet still may require intermittent topical or systemic therapy.
Otitis Externa
Ear infections are commonly seen with allergies. Inflammation occurs inside of the ear canal
resulting in redness, swelling, and itching. Dogs will often scratch their ears, shake their heads,
and/or act tender when touched. Due to the inflammation, many of these dogs experience
concurrent infections which need addressed. Not all ear infections are a result of allergies but
many pets with allergies have recurrent ear infections and/or inflammation.
Hives Hives, also referred to as urticaria, is characterized by raised red lesions on the skin that appear as welts or wheels. Lesions are not hairless unless they arise in an area that already lacks hair. They’re typically ¼ inch in diameter but this can vary. In the case of several, they can often merge together. These are a result of an allergic reaction and hives are often very itchy (but not always). As to what results in this allergic reaction, it can be many things. It can be the result of an environmental allergen (such as pollen), chemical exposure, ingesting any kind of substance (food or otherwise), insect/animal bite or sting, vaccinations, or medications. While anti-histamines such as Benadryl® can help, treatment with steroids are typically required to treat this condition. Even if your pet resolves spontaneously on its own, it is still important to report this incident to your veterinarian especially if it was associated with vaccination or a medication. Pets that have had episodes may have other allergic reactions or the episodes may worsen in the future. In some situations, hives can be life threatening. Swelling of the face or muzzle may also be associated with this condition. If it spreads, then it can lead to the airway being cutoff. If your dog has facial swelling, it is important to remove the collar to help avoid this. These kinds of reactions can also preclude a full anaphylactic reaction. Anaphylaxis is deadly as difficultly breathing and death can result. There are also incidences where the hyperactivity of the immune system can also result in damage or failure of internal organs. If your pet is experiencing hives, it is imperative you get them to a vet as soon as possible to stop the allergic reaction from continuing. Not only does your pet feel awful (really itchy) it can turn into an anaphylactic event. Conjunctivitis and Blepharitis Because allergies can lead to itchy eyes, we may often see redness, excessive mucus production, and/or swollen eyelids. This can result in secondary bacterial infections or trauma of the eyelids from rubbing. Your veterinarian may prescribe special eye drops or other medications to provide relief to your pet. Changes to your pet’s eyes are considered an emergency until proven otherwise. If you see squinting, excessive tearing, swelling, cloudiness, etc. your pet should be seen right away.
Hot Spots (Pyotraumatic Dermatitis) These are red, wet, painful, and sometimes bloody. As they resolve, they may appear dry or scabbed over. They can manifest as a discreet lesions or cover large expanses of the pet's skin. More than one can arise at a time. Hot spots are caused by a pet licking or chewing in that location. The cause of the licking/chewing is often related to fleas, allergies, pain, etc. Hypothyroidism Hypothyroidism is a condition that most commonly affects dogs (it is very rare in cats). In this disease, the cellular metabolism and response is slowed due to the lack of thyroid hormone being produced. Because of this, the body has trouble clearing infections or maintain the skin barrier. Dogs with hypothyroidism may experience recurrent skin infections, unresolving skin infections, development or worsening of allergies. Hyperadrenocorticism Hyperadrenocorticism, or Cushing’s Disease, is the overproduction of steroids in the body. This results in immunosuppression and breakdown of tissues. Recurrent skin infections and hairloss are common presentations. Diagnosing Allergies Allergies are a clinical diagnosis, meaning there isn’t a simple quick test to say “yes your pet definitely has allergies.” Your veterinarian will first conduct an exam to determine if there are any obvious problems such as fleas. They may then request to perform tests such as skin scrapes or impression cytologies. These look for parasites and secondary bacteria/yeast growth respectively. An ear cytology may be requested if the ear canals are inflamed or if they act like the ears bother them. An ear cytology helps determine if there is bacteria or yeast present. Ear inflammation without those present almost always is a result of allergies. A biopsy may also be recommended in situations where an auto-immune disease or cancer is suspected. Some diseases such as pemphigus or cutaneous lymphoma may look similar in some presentations. Allergies are diagnosed by the presence of clinical signs, history, and response to therapy. Allergies may be highly suspected if clinical signs are seasonal (spring, fall). Things get more difficult to discern between atopy and food allergies. It gets even more difficult if a pet has both! If allergies are still suspected after the initial evaluation, then there are a few different pathways a veterinarian can choose from this point.
Response to Medications Because environmental allergies are quite common, a veterinarian may elect to pursue diagnostic therapy. This is a test and treatment rolled into one. If the animal responds well to medications, it can be presumed the pet has allergies. Trouble arises if an animal has particularly severe environmental allergies and/or concurrent problems. I find that pets with severe environmental allergies take 6-8 weeks of consistent and aggressive treatment to see significant improvement. Choice of medications will also make a difference in response. Some medications work better than others. Steroids are typically a diagnostic treatment of choice however newer options such as Apoquel® and Cytopoint® have diminished their use. However, steroids should not be overlooked, particularly in cats. We will discuss therapeutic options later in this article. Secondary infections or underlying issues such as hypothyroidism should also be addressed. Little improvement will be seen even if the allergies are treated as skin infections are itchy and cause continued breakdown of the skin barrier while hypothyroidism results in delayed healing. Allergy Testing First, understand this is not an actual diagnosis of allergies. Allergy testing provides a specific diagnosis in approximately 80% of cases. It defines that the body reacts to a particular allergen i.e. what is causing the allergies. Allergy testing is often done if desensitization or avoidance therapy is pursued. There are two types of allergy tests- intradermal skin testing and blood testing. Intradermal skin tests are considered the gold standard as a visual reaction to the allergen is documented. Allergy blood testing measures IgE antibody titers to different allergens. If it contains a high number of IgE antibodies to a substance, an allergy is presumed to exist. This type of test is considered not as accurate as intradermal tests as an antibody response doesn’t necessarily correspond to an allergic reaction. However, in my experience these tests do provide useful, particularly when a client can not seek referral and testing with a veterinary dermatologist. Dietary Elimination Trial This test is done to rule in or out food allergies. It is the only true diagnostic test for food allergies. While allergy testing can be helpful, it is not definitive and only a handful of ingredients are checked. The goal of a dietary trial is to eliminate the allergen that is causing the reaction. When symptoms have resolved, the patient is rechallenged with the old diet and monitored for reoccurrence of symptoms. A positive response tells us this patient does indeed have food allergies. The downsides of a dietary trial are duration and strictness. A dietary trial lasts 8-12 weeks before a decision is made. An appropriate diet must be fed and isn’t as simple as switching to a different protein type. While this may work in some instances, in most cases this typically
results in confusion for both the veterinarian and owner. A pet may be allergic to multiple protein sources and/or ingredients and preservatives used. Because of the length of a dietary trial, simply switching between protein sources are typically not effective and create a prolonged period of continued symptoms. It is more time and cost effective to utilize a prescription elimination diet for these trials. These diets are also referred to hydrolyzed protein diets. The ingredients in these diets are broken down so small that the body cannot recognize it (no allergic response). Prescription diets included: • Royal Canin Ultamino • Royal Canin Hydrolyzed Protein Diet • Science Diet z/d • Purina HA There is more that goes into a dietary elimination trial than food. It is imperative that the pet receive no table scraps or treats during this time. Preventative medication should be topical or non-flavored (ex. topical heartworm prevention). Even chew toys that are flavored should not be given!!! It is important during the dietary trial that secondary infections and other underlying problems be addressed. Current Therapeutic Options Hydrolyzed Protein and Select Protein Diets These types of diets are utilized in pets with known food allergies as diagnosed via dietary elimination trial. The means of testing is often a means of treatment. The only way to effectively treat food allergies is to practice avoidance. Food allergies do not respond to medications. Some owners may pursue dietary trials to narrow down offending proteins while others may choose to feed a blanket-type food allergy diet. Your veterinarian can help you select the most appropriate food for your pet. Desensitization Therapy This involves allergen-specific immunotherapy which we commonly refer to as allergy shots in people. Desensitization therapy involves giving injections of very small amounts of allergens (as defined by allergy testing) in order to build up their immune tolerance. Some companies have now made nasal drops instead of injections! Response to treatment is not typically apparent for 3-12 months of treatment. Most allergy medications cannot be given to calm symptoms during treatment otherwise the immune system’s response is hindered. The statistics for improvement with allergen-specific immunotherapy are similar to the results seen in humans: approximately 50% of pets show
dramatic improvement in their clinical signs, 25% show some improvement, and 25% show little to no improvement. Antihistamines This class of drugs includes diphenhydramine (Benadryl®), loratadine (Claritin®), cetirizine (Zyrtec®), etc. Unfortunately, these aren’t always great medications to use in our pets. In dogs, less than 25% have an adequate response to the use of an antihistamine alone. They typically must be combined with other forms of therapy. Cats are known to be more responsive to antihistamine use. I have also found in my experience that patients that do exhibit upper respiratory symptoms (sniffling, sneezing) seem to have a better response to this class of drug vs dermal presentations. Steroids Medications such as prednisolone, depomedrol, dexamethasone, etc. are steroids. These were classically our go-to medications for management of environmental allergies. While typically affordable, these medications do have side effects and should not be used for long term management of allergies. Increased hunger, thirst, and urination are common side effects. Because of these side effects, a higher dose is used at first but this is quickly tapered down once the condition is controlled. The medication will then be given at the lowest effective dose. Long term use can result in organ changes and immunosuppression. Higher doses result in complete suppression of the immune system which can result in urinary tract and respiratory infections. They also influence blood pressure and heart function. Long term steroid use can also result in diabetes as steroids lead to insulin resistance. Cyclosporine Brand Name: Atopica® This is an immunosuppressant that is warranted in long term management of atopy cases. It does not lead to organ changes and lacks side effects often seen with steroid use. However, it does cause overall immunosuppression and can be quite costly depending on the size of the animal. It may be combined with ketoconazole, an antifungal, to help reduce its dosage and increase effectiveness. Ketoconazole alters liver metabolism of cyclosporine. Oclacitinib Brand Name: Apoquel® This is a newer generation allergy medication that is both highly effective and specific in how it works. It can be used for seasonal allergies and pets that require lifelong medication. It begins stopping the itch within 4 hours of taking the first dose. Patients are started with a loading dose and then it is tapered down for further use. Patients taking this medication do not experience overt immunosuppression as the action point of this drug is highly specific. Patients taking
Apoquel® can take other medications that may be contraindicated with other types of therapeutics (example: steroid combined with NSAID pain medication is a huge NO NO). Side effects are few and far between and are typically limited to digestive disturbances. Patients at high risk or have certain types of cancer should not take this medication as the specific part of the immune system it suppresses may allow this cancer to grow unchecked. This medication is only labelled for dogs. Dermatologists have experimented with its use in cats and have not seen great results at this time. Cytopoint® This is a very unique compound used in the battle against allergies. It’s not actually a medication but an immunotherapeutic! Cytopoint® is an injection of canine antibodies that specifically attack the protein that results in the itch caused from environmental allergies. If the protein has been neutralized, there is no reaction. This is an injection that is given every 4-8 weeks and starts working within 24 hours. It may take up to 72 hours to see a full effect. In very itchy patients, I often prescribe a week’s worth of Apoquel® for symptom relief while the injection goes to work. In severely affected patients, an earlier second dose may be required or improvement may not be seen until the second injection is given 4 weeks later. Remember this is an antibody that neutralizes the “itch” protein. If a dog is overly reactive and produces a large amount of protein or its allergy pathway is slightly different, this medication may not be completely effective. I have found it to be highly successfully treating canine patients with atopy or seasonal allergies with the majority having an excellent response. Patients that are particularly severe, or if finances dictate otherwise, are placed on Apoquel® to manage symptoms. Cytopoint® has been found to be incredibly safe with very limited side effects. It is only labelled for dogs and cannot be used in cats. Adjunctive Therapies Bathing Even just bathing in cool (not cold) water can help relieve itchy pets. This helps soothe inflamed skin and rinse away allergens (if environmental). There are specific shampoos that can be used that also aid in further relief and healing. Some of these may be soothing but others may actually help restore the skin barrier (Douxo Calm®). Your veterinarian may also prescribe bathing products that help treat secondary skin infections. Harsh soaps should be avoided. Omega 3 Fatty Acid (OFA) Supplementation OFAs disrupt the production of inflammatory chemicals within the skin. By using these supplements, it may be possible to postpone the need of medications or reduce the dose of needed to control symptoms. It may take 6-12 weeks to see a response through
supplementation. It is also important to choose a supplement heavy in Omega 3s as these reduce inflammation. Omega 6 fatty acids are pro-inflammatory and should be avoided. Welactin® is one of my preferred brands. Salmon and sardine oils can also be considered but thorough research should be used prior to administration. Not all supplements have strict processing guidelines nor are they FDA regulated. Frustrating Cases Allergies can be extremely frustrating and expensive for many pet owners. What if a pet has both environmental and food allergies? What if they have a particularly severe case? This is where things get even more frustrating and tough. It is imperative that your veterinarian has a clear and decisive plan of action when one path leads to a dead-end or the desired level of improvement is not achieved. Even pets with only environmental allergies can be difficult to treat. If your pet is taking some of the most effective medications on the market and complete resolution has not occurred, then a dietary food trial should be considered while maintaining current therapy. If no improvement is seen with a high-quality prescription elimination diet and you AND your family have strictly followed elimination guidelines, then your pet may require additional testing, referral to a dermatologist, and/or combination therapies may need to be considered. If a dietary trial was pursued first and no resolution of symptoms were seen, then stopping and attempting environmental treatment may be warranted. If there is no response to environmental treatment, it may be worth instituting both at the same time. It is imperative that other underlying causes are addressed. Pets that have inappropriate responses or recurrent issues should be tested for underlying diseases such as hypothyroidism or hyperadrenocorticism (Cushing’s Disease). Those diseases cause alterations of the immune system and healing, and until they are addressed problems will often persist. Cutaneous lymphoma or autoimmune diseases can also make lesions similar to those seen in allergies. Biopsy is required for diagnosis and should be instituted in cases of high suspicion or show a lack of response to treatment. I have seen some pets with allergies require a combination of medications, food, and desensitization therapy. Some allergies are incredibly difficult to manage and have unfortunately resulted in quality of life decisions. Allergies require lifelong management. There is NO cure for allergies. Also, not all pets respond equally to treatment protocols. While we have a general variety of effective medications and regimens, some pets require treatment regimens that are specifically designed for them. It’s important to realize that response to treatment is not an overnight occurrence. Many pets that have moderate to severe allergies may take 4-8 weeks to see significant changes. Animals with more complicated cases may take longer to see resolution or acceptable management of clinical signs.
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