Inflamed Issues
The impact of allergies on skin, ear and gut health on pets.
Pet allergies are more than a seasonal nuisance. They can significantly impact a pet’s skin, ear and gastrointestinal (GI) tract health, leading to chronic discomfort, repeat veterinary visits and increased demand for effective treatment solutions.
Understanding allergies’ widespread effects is key to supporting veterinary professionals with innovative products and therapies that address these complex cases. With complications from intense itching and chronic ear infections to dietary sensitivities and gut inflammation, pet allergies often require a multimodal approach for effective management.
This article explores how allergies affect different body systems and the various products veterinarians use to help manage allergy-related conditions.
Understanding pet allergies
Allergies are a widespread and complex issue for pets, causing signs such as red, inflamed skin, incessant itching, hair loss, recurrent ear and skin infections, and GI upset (e.g., vomiting, diarrhea, flatulence, bloating). Identifying the underlying cause is necessary to determine the most effective management plan for affected cats and dogs.
Flea allergies
Flea allergy dermatitis (FAD) is the most common skin disease in U.S. dogs and cats. Affected pets are allergic to proteins in the flea’s saliva, and only a few flea bites can trigger a response. In some cases, no fleas are found because the pet removes them through grooming. Although a pet’s entire body can be affected, common areas include the lower back, abdomen and inner thighs.
An FAD diagnosis is usually based on clinical signs, history and response to treatment. If a pet exhibits signs and has fleas or evidence of fleas (i.e., flea dirt), they likely have FAD. Complete elimination of fleas from the pet and their environment is necessary to
manage the condition.
Environmental allergies
Atopic dermatitis (AD) is triggered by an abnormal immune response to environmental allergens, such as grass, tree and weed pollen, dust mites, mold spores and animal dander. All pets are susceptible to AD, but certain breeds, such as golden retrievers, Labrador retrievers, French bulldogs, boxers, and cocker spaniels, are genetically predisposed and at increased risk.
Diagnosing AD involves ruling out other potential causes for the pet’s signs. Once a diagnosis has been made, the veterinarian can perform allergy testing to identify the environmental substances that triggered the response. This information can then be used to create customized allergy medications to desensitize the pet’s response to the allergens.
Food allergies
Pets can be allergic to any food ingredient, but the most common culprits are proteins, such as chicken, beef, dairy and eggs. Pets may also be allergic to more than one ingredient, which can complicate the diagnosis.
Affected pets can develop skin issues, such as year-round itchiness, or GI signs, and about 20% have both. Most pets start exhibiting signs when they are less than 6 months of age or older than 6 years, and in some cases, they have been eating the triggering food for an
extended period with no trouble.
Intradermal and serum allergy testing can’t accurately diagnose a food allergy. The only way to determine if a pet has a food allergy is through a strict elimination diet. This involves feeding a hypoallergenic diet, such as a novel protein diet or one with hydrolyzed protein, for 8 to 12 weeks.
If signs improve, the initial diet can be reintroduced to see if signs return. If the problem recurs, the hypoallergenic diet is then restarted to confirm the diagnosis. To identify the specific ingredient a pet is allergic to, individual ingredients from the previous food can be introduced in small amounts while watching for a return of signs. This helps determine which foods should be avoided in the future.
Allergies and skin
When an allergic pet is exposed to a trigger, such as an environmental allergen, food or fleas, their body releases inflammatory chemicals, such as histamines, which cause inflammation, intense itching and skin barrier dysfunction.
Common skin reactions include:
▶ Itching. Many allergic pets are excessively itchy and exhibit signs such as persistent scratching, licking, chewing and rubbing of affected areas. In severe cases, this can damage the skin, leading to scratches or open wounds.
▶ Redness. The pet’s skin may look red and inflamed, which may be most noticeable on the belly, paws, face and ears.
▶ Hair loss. The excessive scratching and chewing can lead to hair loss in affected areas.
▶ Miliary dermatitis. Affected cats may have multiple red skin lesions covered by small scabs, typically around their neck.
▶ Seborrhea. Dogs may develop seborrhea, which is characterized by excessive scaling,
greasiness and flaking, often accompanied by a strong odor.
▶ Lichenification. Chronic allergic conditions can lead to thick, leathery skin.
▶ Eosinophilic granuloma complex. Cats may develop red, raised and sometimes raw areas of skin on their skin and lips, and inside the mouth.
▶ Secondary skin infections. Allergic pets are prone to secondary bacterial and yeast infections, resulting in crusting, odor and worsening irritation.
Allergies and ears
Allergies are the most common cause of chronic ear infections, or otitis externa, in pets. Approximately 75% of chronic otitis externa cases are caused by environmental allergies, and ear inflammation may be the only sign. Pets with food allergies are also prone to ear infections. When triggered, the pet’s immune system causes inflammation in the ear canal, which increases ear wax production and disrupts the normal skin barrier, making the ear canal more vulnerable to infections.
Pathogens most commonly associated with otitis externa include Staphylococcus, Pseudomonas and Malassezia. Signs of otitis externa include redness, head shaking, scratching at the affected ear and odor or discharge from the ear.
The condition can be extremely painful for pets and can cause complications such as:
▶ Ear canal narrowing. Chronic inflammation can lead to thickening of the skin lining the ear canal, causing the canal to progressively narrow.
▶ Aural hematomas. Excessive head shaking and scratching can cause a blood vessel in the ear flap to rupture, leading to a swollen, fluid-filled blood clot that may require surgery.
▶ Otitis media and interna. Untreated otitis externa can spread to the middle and inner ear.
▶ Neurological signs. If the middle or inner ear is affected, neurological signs, including a head tilt, difficulty walking and facial nerve paralysis, may develop.
▶ Hearing loss. Long-term inflammation and scarring can lead to hearing loss.
The impact of allergies on the gut
While allergic conditions in pets most commonly cause skin issues, affected pets, especially those with food allergies, can experience GI upset as their primary symptom or in conjunction with skin problems. GI signs include vomiting, diarrhea, flatulence, bloating and abdominal pain.
Allergies disrupt the GI tract through:
▶ Inflammation. When an allergic pet ingests a triggering ingredient, the immune system releases cells that cause inflammation in the gut lining.
▶ Altered gut microbiome. Food allergies can cause microbial imbalances, reducing beneficial bacteria and allowing harmful bacteria to proliferate. Studies have also shown that atopic dogs have a significantly lower gut microbiome diversity than healthy dogs.
▶ Increased GI permeability. Inflammation caused by allergies can damage the tight junctions between cells that normally seal the intestinal wall, disrupting the gut’s natural barrier function. This results in a “leaky gut,” which can potentially cause inflammation and other health problems.
Managing pet allergies
Effectively managing pet allergies requires a multimodal approach to address skin, ear and GI issues. Veterinary distributor representatives can help veterinarians to successfully manage allergic patients by ensuring they have access to the right products.
Prescription anti-inflammatory and allergy medications
These products reduce inflammation and itching, improving the pet’s comfort and helping to prevent self-induced skin trauma and secondary infections.
Specific products include:
▶ Apoquel (oclacitinib). This fast-acting oral medication can provide relief for allergic dermatitis and itching.
▶ Cytopoint (lokivetmab). An injectable monoclonal antibody therapy, this medication can provide long-term itch relief.
▶ Corticosteroids. A short-term course of a steroid, such as prednisone, dexamethasone or triamcinolone, is often used to manage an allergy flare-up.
Veterinary prescription diets
For pets with food allergies, novel protein and hydrolyzed diets are necessary for elimination trials and long-term allergy management.
Specific products include:
▶ Hydrolyzed protein diets. Hill’s Prescription Diet z/d, Royal Canin Hydrolyzed Protein, Purina Pro Plan HA
▶ Novel protein diets. Duck, venison, rabbit or kangaroo-based diets (e.g., Hill’s Prescription Diet d/d, BLUE Natural Veterinary Diet N/P)
▶ Limited ingredient diets (LID). Natural Balance Limited Ingredient, Royal Canin Selected Protein
Medicated topical treatments
These products help restore the skin barrier, reduce inflammation and control secondary infections.
Key products include:
▶ Antimicrobial and antifungal shampoos. These products typically include active ingredients such as chlorhexidine, miconazole or ketoconazole.
▶ Moisturizing shampoos. Phytosphingosine, ceramide and oatmeal-based products are often used.
▶ Medicated sprays, wipes and mousses. Examples include Duoxo S3 products, Mal-A-Ket products and Vetoquinol Vet Solutions products.
Flea prevention
Strict year-round flea prevention is crucial for pets with allergies. Key products include:
▶ Oral flea preventives. Simparica (sarolaner), NexGard (afoxolaner), Bravecto (fluralaner), Credelio (lotilaner)
▶ Topical flea control. Advantage Multi (imidocloprid, moxidectin), Revolution Plus (selamectin, sarolaner), Frontline Gold (fipronil, (s)-methoprene, pyriproxyfen)
Ear medications and cleaners
Routine ear cleaning and treatment are essential to prevent chronic ear infections in allergic pets.
Commonly used products include:
▶ Medicated ear cleaners. Chlorhexidinebased or antifungal solutions (e.g., Epi-Otic [salicylic acid], MalAcetic Otic [acetic acid, boric acid])
▶ Prescription ear treatments. Claro (florfenicol, terbinafine, mometasone furoate), Osurnia (florfenicol, terbinafine, betamethasone acetate), Mometamax (gentamicin sulfate, mometasone furoate monohydrate, clotrimazole), Tresaderm (thiabendazole, dexamethasone, neomycin sulfate)
Probiotics and supplements
Supplements can support digestive health and reduce inflammation.
Specific products include:
▶ Probiotics and prebiotics. FortiFlora, Proviable, Visbiome Vet
▶ Omega-3 fatty acids. Reputable products containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)
Allergies have a significant impact on dogs and cats, and especially on their skin, ears and GI tract. With the appropriate medications and products to manage their condition, allergic pets can get relief and enjoy a good quality of life.
