32 min

We Asked A Vet Everything About Pet Allergies, Symptoms & Treatments

Pawp asked Dr. Laura Robinson, DVM all your questions about dog and cat food, environmental, and flea allergies, symptoms, and treatments.


Updated August 04, 2023 • Published June 03, 2020

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We Asked A Vet Everything About Pet Allergies, Symptoms & Treatments

In our Ask A Vet series, Pawp interviews Dr. Laura Robinson on Instagram Live about pet allergies, symptoms, treatments, and more. The questions we asked came from the Facebook group Ask A Vet. If you’d like a vet to answer your questions, join the group and post or tune into the Instagram Live on Mondays at 1 pm. This interview has been transcribed and edited for length and clarity.

What Are The Most Common Allergies in Cats And Dogs?

I'm really glad we did this topic today because it's probably a conversation that I have with owners every single day at work. It's like the most common thing probably that we deal with, especially in California, where it's hot and we're outside all the time around all these different things. So there are basically three different causes of allergies, and those are food allergy, environmental allergy, and flea allergy. So dogs and cats can have just one of those, none of those, all three of those. But yeah, and it comes out with itching and things like that.

How Can You Determine Whether Your Pet Has A Food, Flea, Or Environmental Allergy?

That's a tough question. So you kind of just have to go through one at a time. So by far the most common one is environmental allergies. Flea and food are a little bit less so, but about 20% of all cats and dogs have some sort of allergy to something. So you've got to go down the list. Flea is the easiest thing to take off the list by getting them on a flea preventative and things like that. So you can totally eliminate that being a potential.

And then if they're still having itchiness, they probably have one of the other two. So food, it can look similar in their symptoms and such, so to really eliminate food as being a potential, you have to get them on a diet trial where you put them on, it has to be a prescription diet that's made specifically so that they don't have a reaction to the food. And you have to only feed them that, I usually say for three months. Some people say two. And then see if their skin gets better. So you're basically eliminating flea and food being a potential allergy that way.

And then at the end, if you're really strict with that diet trial and you have them on a flea preventative, and they're still ... You might notice they get a little bit better, but not all the way better. So maybe they have a little bit of food allergy, but also environmental. So then if you eliminate those two things as an option, then you're left with, okay, most likely they have environmental allergies.

Food allergy is probably only 10 to 15% of allergies that I see. So, they should be on a flea preventative anyways. There are fleas everywhere. So I usually will eliminate that as an option and then just treat it as like it's environmental and see what food they're on and try to get them on something different. And if I'm kind of doing everything with the environmental part of it and they're still having the same issues, then I'll try to put them on a prescription diet for three months.

How Can You Identify What Food Allergy Your Pet Has?

So the most common types of food allergy, a lot of people think that it's grain, but it's actually not. The most common ones are actually the foods that have been around the longest, funny enough. So the immune system is basically identifying these proteins that they shouldn't be reacting to, they are reacting to them. They react most commonly to the protein source of the food. So in cats and dogs, actually, the most common food allergies are chicken and beef, dairy, eggs, fish in cats, a lot of the time. So things that you think they wouldn't have an allergy to, those are the most common ones.

There are a couple different options for switching. The goal is to have them on something that they've probably never had before in their life, so that means usually a prescription diet because these companies process their food differently. They clean all their equipment off really well before making these bags of food that are for food allergies so that there's 0% chance that there's even a tiny bit of chicken or beef in that kibble. So you have to go the prescription food route, unfortunately. You can't just go pick up something, you have to get it from your vet. So oftentimes I'll switch them to something that you wouldn't think of them having like venison or duck. Those are kind of the most common ones.

In the last couple of years, a couple companies have come out with these hydrolyzed protein foods, which basically means that they've broken down the proteins so much so that the animal can't react to the protein. It's not really one specific meat or another, it's just basically these proteins broken down so small that your body can react to them. So that's another option. It's called hydrolyzed protein. Usually I'll switch to venison, hydrolyzed protein, duck. They used to have kangaroo, funny enough, but now we can't get kangaroo in the US. But the goal is to have them on something they've never had before.

What Are The Symptoms Of Food Allergies In Your Dog Or Cat?

They can have skin issues or digestion issues. Either one or both. If they're itching, vomiting, have diarrhea or chronic, loose stool that's not really formed. That makes it a little bit more likely that it's a food allergy. They can get chronic ear infections. Time and time again, skin infections. All those kinds of things. So it looks similar to the other allergies, unfortunately, but they will be itchy and you might notice if you switch foods that they get extra itchy. Oftentimes I see that too.

Same thing with cats. So cats will itch themselves all over. They'll excessively groom. They can also have GI issues as well. So yeah, kind of same for both.

How Do You Identify Which Environmental Allergy Your Dog Has?

For the environment, the best way to know what that is usually a skin test, kind of like with people. If you're allergic, you'll go to your doctor and they'll inject little amounts of the allergen into your skin and see if you have a reaction. So that's the best way to do it with dogs. Sometimes they're not 100% and there can be some false positives and such, but that's really the only way to do it. Kind of just managing their symptoms, you can do immunotherapy where you take your dog in and they get allergy shots and stuff too. There's also blood tests that you can get. The vet dermatologists in general, I think recommend the skin testing a little bit moreso. It's slightly more accurate than blood, but you can do either or both.

What Are The Most Common Environmental Allergies In Dogs And Cats?

Just like people, some dogs will have environmental allergies and it's kind of the same thing as the food. Their body's reacting to something that it shouldn't. It's a genetic thing that's more breed specific, like in bulldogs, those are your poster children for allergy issues. It's just their immune system overreacting.

The most common ones are things like grass, dust mites are a big one. So I tell people, maybe get your carpets cleaned and up your vacuum cleaning at home, too. They can be allergic to ragweed. They can also be allergic to fleas. Those are the common ones, but pollens, any type of plant out there. If you go get a test, they'll test them for like 60 different types of plants.

Is There A Cure For Environmental Allergies In Pets?

Environmental allergies are probably the most frustrating of the three to treat because they're not curable. Allergies are tough. I always tell people like, "Good news is they have allergies. It's nothing that's life-threatening. But bad news is they're always going to have allergies. There's no cure for environmental allergies." So like I was saying, you can do that immunotherapy where you go into a dermatologist to get little amounts of all these allergens injected into the skin and do that over time so the body stops reacting to it. So that can decrease the severity of the signs a lot of the time. It's not 100% curative, but it can help. Unfortunately, usually it's just a management process.

Hopefully it's more of a seasonal thing for that pet. For instance, if they're allergic to dust mites, that's a little bit more common in the winter time or whatever they're allergic to that time of the year, that they're blooming. Some dogs get really bad allergies in the spring. Some dogs get really bad allergies in fall. So hopefully, you're just dealing with it a couple times a year, but oftentimes anti-histamines can help. I tell people to get on supplements. I know Pawp has a really good skin supplement with fish oils that help the skin barrier. Try to get on a skin supplement for sure. Up your bathing a little bit. Aloe oatmeal baths are really good for allergic dogs. You're trying to avoid a skin infection. Try to do that every other week. That kind of thing.

Anti-histamines can help. I tell people to get on supplements. I know Pawp has a really good skin supplement with fish oils that help the skin barrier. Try to get on a skin supplement for sure. Aloe oatmeal baths are really good for allergic dogs. You're trying to avoid a skin infection.

But unfortunately, a lot of it is just trying to have it not to get to the point where it turns into a skin infection. And I don't know if you've heard of it, there's stuff called like Apoquel and Cytopoint. Those are two big medications that we use that help manage the itching part of it. So you're just managing the symptoms. You're not really treating the allergy, unfortunately, except with the tests.

You can do blood tests or skin tests from your dermatologist. That's the only way to really know what they're allergic to, otherwise you try to just manage their symptoms, because a lot of people can't afford that.

How Can You Prevent Your Dog Or Cat From Flea Infections?

Yeah. So dogs and cats can both get flea allergy and that's the third type of allergy. They're basically having a reaction to the saliva of the flea from the bites. So even one bite from one flea can set off this cascade of itching and skin issues. So I tell everyone, cat, dog, even if your cat's indoor only, I've seen cats come in with parasites from indoor only. I've seen cats have fleas when they're indoor only. So I tell everyone all the time, have your dog and cat on a flea preventative. I know Pawp has an online pharmacy that you can go on there and they have really good options. There's so many flea and tick medications out there. I prescribe Nexgard a lot. That's a big one. Bravecto, Trifexis, all of those are kind of ... There's a lot of other ones. Simparica, that's another one.

But yeah, getting them on a flea preventative, not just for the flea allergy component, but also if dogs and cats ingest fleas from kind of trying to bite at themselves, that's how they get tapeworm. They can also get different bacterial infections from fleas. Fleas can also bite you and cause issues. So just get them on it. Usually that means once a month. Some of these medications are every three months now. You just have to follow what the label says and do that.

How Do You Treat Flea & Tick Allergies? Which Is The Best Method?

My favorites are probably the oral chewable tablets for dogs. And then cats, I probably like the topical stuff a little bit more, just because a lot of the chewable stuff for cats I've seen them have a reaction to, like vomiting and stuff. So those are the ones I found most effective. There's so many different options out there. There's good topical ones for dogs too, if you prefer that. And then there's also the different collar options, as well.

Unfortunately, a lot of the products that do not require a prescription, the ones you can just buy over the counter at like Petco and PetSmart without your vet having to write a prescription, unfortunately, a lot of those don't work that great anymore. Fleas have kind of grown genes that are ... they're immune to them now. So I always tell people, talk to your vet, just get whatever it is from your vet, whatever type you prefer. But all of them can be effective. It's not necessarily the type, moreso the brand. And the different ones that I found to be effective or not, because a lot of them have lost their effectiveness.

Canva - Scared dog at home

How Do Flea Collars Work?

So the collars kind of release these general medications topically, same thing with the topical medications. There's so many, again, out there, the orals and stuff, but a lot of them have different properties. And then they basically the fleas' kind neurologic functions. They interfere with their body, basically, their nervous system and cause them to die and fall off. So that's how most of them work, but each one works a little bit differently.

What Are Flea Allergy Symptoms?

It can mimic either food allergy or environmental allergy symptoms. Usually with dogs, it's kind of on the back half of their body, like around their tail, that kind of thing. Cats, they're also kind of back there, but they just will start grooming themselves excessively all over, which is kind of what they do with environmental and food too. So it's a little bit hard.

If you see a flea, obviously that's easier, but you can also see evidence of fleas too. Like sometimes if you see what looks like little tiny specks of dirt, that's actually flea poop. And if you take it and put it on a wet paper towel, it'll actually come out red, because that's blood from their digestive system. So it's called flea dirt, but it really is their poop. So that's another way to know if you might have fleas or not.

How Long Do Fleas Live? How Do You Get Them Out Of Your House?

So the life cycle of the flea, because they lay eggs and then oftentimes those eggs will fall off and they'll become like pupae and then larvae and then fleas, so they have a full life cycle. So a lot of the flea allergy is also, they can kind of hibernate in that form of the pupae in your carpet and stuff for a while. So the goal is you also want to decontaminate your house and such, too. So there's different kind of ... I know like Fleabusters is one coming to mind, but there's like powders and stuff that you can put on your carpet to make sure that you're not going to have another wave of fleas erupting in a couple months. So you need to keep them on flea control consistently for like six months, a year to really break that cycle is what he's talking about. So, you're not just killing the live ones, but you're continuing to treat your dog for the ones that might come up in a month or two or three.

What Are The Symptoms Of Flea Allergies?

So they just pretty much scratch themselves like crazy. It's just this crazy itching sensation. So you'll notice them chewing up I said like the back half of their body, so around their tail a lot of the time. But it drives them crazy, because it's just this crazy itchiness they feel all the time. And then licking themselves so much and chewing at themselves so much they can give themselves a secondary skin infection. So I always tell people, any of these allergies it goes for too, but you come in, you're, one, trying to stop their itching, whether that's getting them on a flea preventative, switching their food. And then two, you're also trying to treat the infection. So you're treating the itching and you're treating the infection. So both of those are different.

Sometimes the dogs and cats just come in and it hasn't gotten to the point yet where they have a skin infection, so I'm just treating the itching at that point. But when they come in and they're red and there's pustules or scabs or skin flaking, blood sometimes, anything like that, or they're really red and inflamed, then that means they have a secondary infection. So then you have to get them on antibiotics and sometimes injectable stuff, upping their bath, all those kinds of things.

I put a reminder on my phone every month to ... I do my dog's Nexgard once a month, so I just know on the 15th is when I do it. But Pawp makes it really great, because you can get the skin supplement delivered and then also the flea and tick preventative. So it helps you to remember to do it, when it's getting delivered every so often too. So that's really great also.

How Do You Prevent Second-Degree Skin Infections In Cats And Dogs?

So I tell people, just don't wait. First signs of itching, get your dog into the vet so you're trying to not get to that point when it's that bad, where there's an infection there. So, it's really good to bathe them every so often. Aloe oatmeal shampoo works really good. That's usually the one I prescribe. Unless they have a really bad infection, then I'll do more like medicated shampoo and such. So I usually tell people bathe them. Cool water is kind of the best, so not hot because that would make the skin even more irritated and red. And then let the shampoo sit on them for about 10 or 15 minutes to soak in before you start rinsing it off. There's also medicated wipes that you can use on their paws and their skin.

Oftentimes they can get ear infections, too. That's super common. So with those, you have to usually get some medicated ear flush or ear cleaner, and then also some drops, unfortunately, to treat that. And sometimes you need oral antibiotics for the ears as well. But I always tell people, don't wait because the longer you wait, the worse it's going to get. And it's going to be a lot cheaper if you go in the first signs before it gets really bad, because then you're just over your head doing so many different things and coming in even more often. So anti-histamines help a little bit, too. Like you can give Zyrtec or Benadryl, sometimes that'll help. Not a ton, but it may help a tiny bit.

What Medicines Treat Allergies? How Often Should You Give Them?

Dogs and cats can take Benadryl. It's a little tough with that because, just like us, it can make you a little sleepy. So sometimes its hard to tell, are they just not itching themselves because they're a little bit more sleepy, or is it actually working and they're not itching themselves? So I think that's confused a lot, but that's an easy way to try it out too. If your dog also ever has hives or anything like that, Benadryl works really great for that. Kind of like with people, you're having a reaction to something, you can take Benadryl. Usually the dose for dogs and cats is about half of their weight in milligrams. So you have a 50 pound dog, they would get a 25 milligram Benadryl. Then same thing with cats. You can do that once or twice a day. So about every 12 hours, is fine. And oral. Oral is the best way.

What Other Things Cause Skin & Coat Issues In Cats And Dogs?

So, yeah, stress can do a lot of things with dogs, just like people. I see it also a lot of times cause GI issues. A lot of people will come in and be like, "Yeah, I left her," or, "I boarded my dog," or, "I left for a couple of days and then they got diarrhea and there was blood in it." So they can get stress colitis, it's called. We see that a lot when they're in the hospital for the day, because they just get so stressed out that they get diarrhea. But yeah, other ailments can come up too. Stress in general decreases your immune system over time, so it makes other things more likely to come to surface. So things like if your dog has separation anxiety, that can take it on. If you move to a new place, new situations, new people, you have a new baby, something like that. All of those can bring on skin issues for sure.

Canva - Dog Scratching Itchy Ears.

How Do You Treat Skin Issues?

Those are kind of the main ones. Like supplements are a big one. I know I mentioned that, but Pawp has a really great skin supplement on their website. If you can get that consistently, that's great. There are different foods too. If your dog doesn't have a food allergy, there are foods that are for skin sensitivities and they have added fish oils and stuff in there too. So you can get them on a skin-specific diet. And giving them consistent baths, like I was saying, every ... I like to do it once a month in general, just with my dog who doesn't have allergies. If you have a longer hair dog, you might want to do every couple months. But if they have really bad skin issues, you can do it every week, every other week.

Anti-histamines, like I was saying. You could do Benadryl or Zyrtec. That'll sometimes help. But yeah, a lot of the times you need more hard-hitting medications. Sometimes we'll use steroids, if they have really bad skin irritation. That'll kind of bring down the redness and inflammation while you're treating the infection. So that's an option. And then there's newer stuff like Cytopoint, which is an injectable medication that helps itching. It lasts about one to two months. So that's really easy for a lot of people. And then Apoquel is a big one too that's an oral anti-itch medication that you give every day to help with the itching too. So dogs that are just kind of allergic to everything, you do have to usually have them on something longterm like that.

Can Dogs Or Dogs Give Humans Fleas?

Flea allergy is not zoonotic, but humans can get bit by fleas, also. And it can transfer to other animals in your house. All of that type of thing. So definitely had a flea or two jump on me at work. It happens.

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