Feline Allergy Testing: Identifying and Addressing Your Cat’s Allergic Triggers
Does your cat suffer from relentless itching, overgrooming, or mysterious skin issues? Allergies could be the culprit! In this episode of Your Vet Wants You to Know, we explore how veterinarians use allergy tests in cats to identify and manage feline allergies, helping your cat live a more comfortable, itch-free life.
🎧 Listen to the full episode below:
How Do Allergies Affect Cats?
Unlike dogs, cats tend to show allergies in unique ways, such as:
✅ Overgrooming (leading to bald patches, like Otto, the “pantsless” cat)
✅ Head and neck itching (like Tinta, who struggled with severe discomfort)
✅ Skin reactions such as scabs (miliary dermatitis)
✅ Plaques or ulcers known as eosinophilic granuloma complex.
To effectively treat allergies, it’s crucial to identify the specific trigger(s) behind your cat’s symptoms.
What Are the Main Allergy Triggers in Cats?
Cats can have one or more allergic triggers, falling into three main categories:
Even a single flea bite can trigger intense itching in allergic cats. Since allergic cats groom excessively, fleas may be difficult to spot. The best way to rule out flea allergies? Consistent prescription flea prevention for all pets in the household for at least 8–12 weeks.
Food allergies in cats are often caused by common proteins like chicken, beef, or fish. However, unlike in humans, there’s no reliable blood, saliva, or hair test for food allergies. Instead, veterinarians diagnose food allergies through an elimination diet trial with a prescription hypoallergenic or novel protein diet for 8–12 weeks.
3. Environmental Allergies (Feline Atopic Skin Syndrome)
Just like humans, cats can be allergic to:
🌿 Pollen
🏡 Dust mites
🦠 Mold spores
… and even human dander!
Because you can’t eliminate environmental allergens, long-term management is necessary.
How Vets Use Allergy Tests in Cats: A Step-by-Step Approach
Veterinarians use a process of elimination to pinpoint the cause of your cat’s allergies:
🔍 Step 1: Rule Out Flea Allergies – Even if you don’t see fleas, prescription flea prevention for at least 8–12 weeks is essential.
🍗 Step 2: Food Elimination Trial – A strict prescription diet for 8–12 weeks helps determine if food allergies are to blame. If symptoms improve and return after reintroducing the old diet, a food allergy is confirmed.
🌎 Step 3: Environmental Allergy Testing – If flea and food allergies are ruled out, your vet may perform intradermal skin testing or serum allergy testing to identify environmental triggers.
Treatment Options: Can Allergy Tests in Cats Help?
Once environmental allergies are diagnosed, allergy testing can help guide allergen-specific immunotherapy (ASIT)—also known as allergy shots or drops. This treatment gradually desensitizes the immune system, reducing the severity of allergic reactions.
⏳ Immunotherapy takes 6–12 months to show results but can provide long-term relief, reducing the need for medications and improving your cat’s quality of life.
What’s Next?
In the next episode, we’ll dive into treatment options for feline allergies and how Otto, the “pantsless” cat, regrew his fur!
📌 Want to learn more?
✔️ Browse related episodes on food allergies and allergy immunotherapy.
✔️ Keep reading for full transcript and images of allergic cats.
✔️ Need a veterinary dermatologist? Check our resources page to find a specialist near you!
Table of Contents
Full Transcript:
Dr. Lancellotti: Welcome, everyone, to today’s episode of Your Vet Wants You To Know. In the last episode, I talked about the different ways that allergies can show up in cats, such as loss of fur from over grooming (as was the case with my friend Otto, a very allergic young cat who came to see me at Veterinary Skin and Ear in Los Angeles, after he had groomed off all of his pants). I also talked about my patient, Tinta, (whose head and neck was incredibly itchy) and how she improved with treatment of her allergies. We can also see problems like miliary dermatitis, which are little scabs all over the cat’s body, as well as large red plaques called eosinophilic granulomas.
Cats can develop any of these reaction patterns, in response to their allergic trigger(s). The three main allergy triggers in cats are flea allergies, food allergies, and environmental allergies. Figuring out the pet’s trigger really helps us, not just in terms of improving their quality of life, but also in minimizing the amount of medications that a pet needs to be comfortable, as well as minimizing the number of vet visits throughout that cat’s life. Because unfortunately, allergies are a lifelong disease. This is something that we don’t cure. It’s something that we manage.
Does My Cat Have Ringworm or Allergies?
What’s important to keep in mind is that cat allergies can look like a number of other health conditions. While it may seem frustrating to do multiple tests, to check for different diseases, this ultimately allows us to make sure we’re giving the pet the best chance at relief. Especially, when it comes to allergies, which are lifelong, and they require management to give the pet a good quality of life. Ringworm, which is a fungal infection, is a good example of a disease that your vet may suggest testing for, if we’re worried about allergies. Sometimes, this can look similar, and is generally fairly easy to diagnose with the lab tests that we have available these days.
Autoimmune Disease Can Look Like Allergies in Cats
For cats that have problems on their face, herpes virus can cause problems around the eyes and the eyelids. An autoimmune disease called pemphigus foliaceus can cause significant crusting and scabbing of the ears, the face, and the chin. These cats may need a biopsy to get a diagnosis. We typically recommend biopsy be performed by a veterinary dermatologist, if that’s possible, as dermatologists have advanced training in picking which areas to biopsy, as well as interpreting the results. These diseases, while they may look like allergies, are treated much differently, which is why we want to know exactly what the underlying problem is.
Parasites Can Look Like Allergies in Cats
Parasites, such as scabies and demodex mites, can be looked for using a simple test called a skin scrape, which your veterinarian may do to look under the microscope for mites. Sometimes, mites are tough to find, so many common flea and tick products actually treat for mites.
By giving your cat a prescription flea and tick prevention, we can often address any possible mites that may make them itchy, as well as start addressing the first of the three allergy triggers. If we want to not just treat the allergies, but rather work on getting them better managed so that we’re not stuck in the cycle of the pet getting better with medication, and flaring back up as soon as the medications are finished, we need to figure out what their triggers are.
Flea Allergies in Cats
We’re going to talk about the three main allergic triggers and how we can identify which triggers a specific cat will react to. Those triggers are insects (primarily fleas), food proteins, and environmental allergens.
Even a single flea bite can cause a severe allergic reaction in cats. This causes intense itching and inflammation, most often on the cat’s rump and belly, but it can happen anywhere. Fleas are a common issue, but the good news is that they’re also one of the easiest to manage with consistent flea prevention.
Food Allergy Tests in Cats
Our second trigger is food allergies. Cats can develop allergies to specific proteins in their diet (chicken, beef, or fish). Food allergies might also cause gastrointestinal signs like vomiting, loose stool, or diarrhea. There are no saliva, hair, or blood tests that are accurate in the diagnosis of food allergies, so identifying a food allergy often involves a strict elimination diet trial, using a prescription hydrolyzed or novel protein diet, under the guidance of your veterinarian.
I know that it seems like you may be able to just change things up, on your own, at home, but trust me- you really want your veterinarian to give you good guidance on how to do an elimination diet trial, to truly know whether food allergies are causing a problem for your animal.
Environmental Allergy Testing in Cats
Finally, cats can be allergic to substances in their environment (pollen, dust mites, or mold spores). Anything that causes hay fever-like symptoms, in people, can cause allergic skin disease, on cats, as well. And just like how we can be allergic to cats, they can be allergic to humans.
Environmental allergies are also, technically, referred to as feline atopic skin syndrome. This disease is a diagnosis of exclusion. That means that in order to diagnose environmental allergies, you have to exclude all of the other diseases first- things like ringworm or mites, as well as other allergic triggers like fleas and foods. Environmental allergies tend to be more challenging to manage because unlike flea allergies or food allergies, you can’t eliminate the cat’s exposure to the environmental allergens.
Testing for Allergies in Cats - Start with Fleas
So how do we figure out what’s causing your cat’s allergies? It’s a process of elimination and collaboration between you and your veterinarian.
Step 1: Rule out flea allergies. We start by ensuring that your cat is on an effective flea prevention regimen. Even if you don’t see fleas, we can’t rule them out until we eliminate that possibility. And that’s because there is a crazy amount of overgrooming that happens, when a flea-allergic cat gets bitten by a flea. They will groom that flea right off of their body and into their mouths, which can actually lead to tapeworms that fleas often carry.
A parasite treatment trial typically requires all pets in the household to have prescription-level flea prevention for 8-12 weeks. Here, in Los Angeles, where I practice, the over-the-counter flea medications are no longer reliably effective against the flea population. It is a very aggressive flea population, so you really want to make sure that your pets are on a prescription flea prevention that is going to eliminate the possibility of fleas sneaking a bite here and there, and triggering ongoing allergic reactions. If you remember Otto, from the last episode, his family vet had him on a great parasite prevention plan to make sure that fleas were not making his allergies worse.
Testing for Allergies in Cats - Elimination Diet Trial
Step 2: Perform a food elimination trial. If the symptoms persist despite good flea control, we often move next to an elimination diet trial. An elimination diet trial involves feeding your cat a prescription diet for 8-12 weeks and avoiding all other foods, treats, or table scraps. Anything else needs to be cut out.
This can be complicated, especially with cats. Episode 2 on food allergies, and episode 17 on diet trials, will be really helpful for you to understand this at-home diagnostic test and come up with a plan in partnership with your veterinarian.
If your cat improves during the diet trial when they come off medications and their disease returns (or flares) in the first week or two, either when their old diet is reintroduced (when the challenge feeding occurs), then voila! We’ve identified a food allergy.
Otto also did a strict eight week elimination diet trial, using a prescription hydrolyzed protein diet, under the supervision of his family vet, before coming to see me. And because his signs continued, at the end of the diet trial, his vet then referred Otto and his family to come see me for management of his environmental allergies.
Testing Cats with Environmental Allergies for Immunotherapy
If addressing fleas and addressing food has not solved the issue, then environmental allergies are the likely culprit. As I mentioned before, these are more challenging for us to manage long-term. Once we’ve diagnosed environmental allergies by excluding other diseases and triggers, we may perform intradermal skin testing, or blood testing (or both), to figure out which environmental allergens are causing problems for your cat.
Allergy testing is not helpful in telling you which allergens your pet needs to avoid, as they will likely be exposed to pollens that are coming from miles and miles away. Even if they are an indoor only cat. And many allergens exist indoors- things like human dander and dust mites. And while these tests don’t provide a perfect answer, they can help us identify the key allergens that we need to target, with our treatment, known as allergy immunotherapy.
I will mention again- there is no diagnostic test that is accurate, for food allergies, other than the elimination diet trial, so please do not submit allergy testing that is looking at what foods your animal should avoid. This is not accurate.
Allergy Immunotherapy in Cats
Allergy immunotherapy is a holistic approach to allergies. It helps retrain your pet’s immune system, to not overreact to the allergens that are triggering their problems, by giving the pet very small doses of pollens or dust mite extracts, as injections or drops under the tongue.
Allergy immunotherapy takes about 6-12 months to start working. If your pet is one of the 65-75% of pets that improves with immunotherapy, it’s continued long-term, to help manage the disease, so that we don’t have to use as many medications to treat the clinical signs of the disease, because the disease is less severe over time.
Immunotherapy is very helpful in establishing a safe long-term management plan. I’ll talk more about immunotherapy, in the next episode, when I dive into different treatment options that are available, and the current research behind each option, so that you can talk with your veterinarian about what might be right for your cat.
If you’re local to Los Angeles, you can make an appointment for your allergic cat with me, or the other fabulous dermatologists, at Veterinary Skin and Ear. But if you’re looking for a veterinary dermatologist in your area, check out the resources tab on the website. There’s a link to find a specialist.
Scratching the Itch
I like to end each episode with a segment that I call Scratching The Itch. This is designed to highlight something- a product, a website, a human interest story- that provides relief or just makes you feel good. Hence, scratching the itch.
Today’s ‘scratching the itch’ is an organization called Pride VMC. The mission of Pride VMC is to create a better world for the LGBTQ veterinary community. Their vision is an empowered LGBTQ veterinary community that embraces well-being by being their authentic selves. Pride VMC has a lot of resources for veterinary students and veterinarians, as well as allies. There’s mental health support, DEI education, and also a job board if you’re looking for employment. They also offer mentorship opportunities for students and new graduates. You can check out their website and consider becoming a PRIDE VMC member, which is open to the entire animal health and veterinary community, regardless of role, race, color, religion, national origin or citizenship status, sex, gender identity or expression, sexual orientation, age, disability, or military status. And allies are welcome, as well. Please consider donating. Pride VMC is a 501c3 organization and all membership dues are tax deductible. You can check out that link, in the show notes, if you’d like to support their mission.
Thank you all for listening, and be sure to join me again for the upcoming episode, where I will talk about treatment of allergies in cats, and you’ll hear about how Otto regrew his pants. I look forward to your next visit with Your Vet Wants You To Know.
References:
- Santoro, D., Pucheu-Haston, C.M., Prost, C., Mueller, R.S. and Jackson, H. (2021), Clinical signs and diagnosis of feline atopic syndrome: detailed guidelines for a correct diagnosis. Vet Dermatol, 32: 26-e6. https://doi.org/10.1111/vde.12935
