How can I tell if my dog has an allergy?

If you have an allergy, you know how much of a pain it is. For some people, avoiding nuts is like walking over a minefield blindfolded. For others, they spend all summer with what’s basically a cold thanks to hay fever. Yeah, they’re not nice.

But at least when they start flaring up we can have a good moan about it. And if it gets bad enough we can go to our doctors for treatment. But when you’re a dog you can’t do that. They can’t talk and tell us what’s making them feel bad.

So it’s up to us as their pawrents to stay on the lookout for any warning signs. Where do you even start though? Let’s take a look at how you can tell if your doggo is suffering from an allergy.

A quick word before we start

For this blog, we’re going to focus mainly on allergies, with a little bit about intolerances and sensitivities. The three terms are often used interchangeably, and while they all lead to a super uncomfortable pup, they aren’t equal.

Allergies are an immune response, and can be potentially fatal. Whereas intolerances are slightly less severe digestive responses. Take hay fever and lactose intolerance, for example. With hay fever, when pollen hits your system, your eyes go all watery and your nose is like a leaky tap. With lactose intolerance, when you eat cheese on toast despite your body not agreeing with it… well, the time spent on the loo speaks for itself. Both systems are fighting hard to remove the unwanted guest from your body, but they do it uniquely in their way. 

A sensitivity, on the other hand, is something that affects your pup, but it’s not necessarily permanent. For example, a weakened immune system from not getting the proper nutrition, or new medication leading to reactions that otherwise wouldn’t bother your dog.

So keep that in mind as we talk about allergies. You can find out more about the distinction in one of our other blogs. If you’re concerned about intolerances, the short version is “look at their poop”. If it’s consistently runny, something likely isn’t right. But we’ll dive into that fun topic shortly.

What can dogs be allergic to?

Just like humans, our doggos can be allergic to pretty much anything. It could be something they ingest, like food, medication, or minerals, or it could be anything their body comes into contact with. 

Some breeds are more susceptible to allergies than others. If you have a Bully breed, you probably already know that they’re more prone to food allergies, intolerances, skin issues, and other problems thanks to them being walking wrinkle machines. For them, their food plays a massive part in reactions, so the good news is most conditions are likely reversible. We’ve put together a list of the dog breeds most likely to suffer from an allergy for you in our blog section, but the reality is that all dogs can suffer, and whatever works for one doesn’t mean it will work for the other. 

When your dog has an allergy, they go through the same uncomfortableness as us. But they affect them slightly differently, though. Our allergy organ, as humans, is our respiratory system. If I get stung by a wasp and don’t have my EpiPen on my (which is alarmingly often), I’ll end up in anaphylactic shock, and I wouldn’t be able to breathe. 

On the other hand, if George eats lamb or carrots, or brushes up against a monkey puzzle tree, or ingests any of his many allergens, he’s likely to have a wild flare-up on his skin, and he’ll be licking, scratching, and chewing at his paws like crazy. That’s because a dog’s allergy organ is their skin.

Allergies, intolerances, or sensitivities in dogs are something that we should take seriously. Left unchecked, they can cause avoidable health issues such as 

  • Secondary skin infections
  • Further allergies
  • Painful, unnecessary symptoms
  • Overall poor quality of life
  • Behavioural changes

That last one’s understandable. You’d be pretty moody too if you were uncomfortable all the time, and who would blame you for lashing out? To give your dog the quality of life they deserve, it’s worthwhile keeping an eye on how they behave. Of course, just having any of these symptoms could be a sign of a different medical condition. However, if your dog has both skin and gastrointestinal symptoms, it’s a good indicator they have an allergy. 

dog allergy 2

What to look out for

Because the skin is their allergy organ, it can be a little easier to spot a reaction. However, it’s important to remember that while there are indicators of what a reaction could be, not every scratch is an allergy, sensitivity, or intolerance. Sometimes a lick of the paw could be precisely that. But there’s always that slim chance that it’s an indicator of something causing them pain.

Or maybe it’s a bacterial infection, a different medical issue, or even just fleas. Continuous, out-of-the-ordinary scratching, however, could mean there is a reaction going on.

Keep in mind that environmental allergies are likely to be seasonal, with pollen count being higher in the summer, for example. If they suddenly start acting better, could it just be that you’re heading into autumn so the allergens aren’t as effective?

These are factors to think about as we run through this long list of symptoms. All 11 are common telltale signs, so keep your eyes open for them. If you can catch these early, take action sooner rather than later to alleviate the cause.

Korma diarrhoea

It’s OK to admit it. As pawrents, we are the weirdos that watch our pups poo to make sure they’re fine. Poo will never smell fresh, but if you’re wrenching your guts out trying to pick it up, that’s a pretty good first clue something is amiss. Note the colour and consistency. Dog poop tells you a lot about their health. It’s like a Dulux colour chart but less glamorous.

Eye-watering farts

Talking of glamorous, let’s face it, farts never smell delightful either. But if your pup is constantly making your stomach churn, it could be a sign of a problem. This is also a symptom of  intolerances, so bear that in mind. It can cause digestive distress, such as bloating and gas. Diarrhoea and flatulence are the outcomes. 

Dog scratching


The odd little scratch behind the ear now and then isn’t a warning sign. We all do it. But incessant scratching that won’t quit is a sign that something isn’t quite right. Especially when your pup is licking and chewing at themselves too. If they disagree with their food, it can cause dry, flaky skin which makes them want to scratch. In addition, environmental triggers, such as pollen, certain soaps, essential oils, or mould, could be causing contact dermatitis – a skin irritation.

Dog licking

Excessive licking

In the animal kingdom, licking can be their way of grooming themselves. So just because your dog licks daily isn’t necessarily a sign of trouble. On the contrary, it can be a good release of feel-good hormones like dopamine and endorphins. Imagine having back tickles or hair strokes? It’s a similar sensation for them. Then there are times where they lick out of boredom or anxiety, like when we bite our nails.

Abnormal licking, however, can be an indicator of an allergy. Your pup often finds an itchy spot easier to reach with their mouths than their paws. Treat licking just as you would with constant scratching. If you notice it happening around the same spot, or hair starts to fall out, that’s your sign something isn’t right. Often you’ll notice stains around the mouth and paws, especially in white-haired dogs. This is from the enzymes in your pup’s mouth.

Dog chewing

Chewing at the feet

As is the case with scratching and licking, some paw chewing can be perfectly normal behaviour. But if you’re noticing it’s happening excessively, the hair is wearing thin, or if the paws are red and swollen, it could be an indicator of an allergy.  

Dog shaking

Head shaking

If we get an itchy ear, we might use a cotton bud or a sneaky finger for scratching away the irritant. Our pups, unfortunately, aren’t blessed with fingers and thumbs, so they don’t have the same way to relieve themselves. So instead, they’ll shake their heads. It could be something as innocent as dirt or grass from all that rolling around in the garden again

But when they have an allergic reaction, it can affect the skin on their ears. In an attempt to get rid of the irritant, your dog may try to shake it off. As with anything, observe their other behaviour. If your dog is shaking their head a lot and you’re noticing they’re in a lot of pain, or there’s a smelly discharge, it’s worth getting to the vets as it could be any number of other conditions. When combined with some of the other symptoms listed here, head shaking can often nod to an allergy. 

Dog hives

Heat spots or hives

AKA annoying, itchy, uncomfortable red patches or bumpy spots that show up on your pooch. Acute moist dermatitis – or heat spots – is tiny red spots that start as little red patches that worsen over time. Hives are recognisable by their raised bumpy appearance and heat spots from their redness. Aggressively red skin is especially noticeable in white-haired dogs. 

Licking, biting, and scratching make both of these worse and can be extremely painful for your pup. From experience, I’ve seen many dogs suffer like this for months because they’re put on treatment courses that prove ineffective. You want to get to the heart of what’s causing it before you try to treat it.

Dog allergy 3


Sometimes dogs are just tired. George will sleep for most of the day by my desk while I’m working and comes alive at night as soon as he knows I’m off the clock. Instead, be mindful when they increasingly become tired from nowhere and start showing disinterest in eating and playing when they’re usually bouncing off the walls. If your pup is generally at your ankles when you’re walking to the bathroom, but now they’re nowhere to be found, it could be worth checking in on them. Allergies don’t cause lethargy, but all that licking, scratching, biting, shaking, and the immune system doing its best to fight the allergens can be exhausting, especially for old-timers or young, growing pups. 

Dog hair loss

Patches of missing hair

When we were looking at dogs to rehome, we saw this beautiful German Shepherd, Sophie. The first thing my boyfriend said was “shotgun not cleaning up all that hair”. Between George and I, there’s already enough moulting going on in our household. Losing hair is perfectly natural. Some dogs are more prone to baldness than others. Typically, these breeds are:

  • Greyhounds
  • Whippets
  • Chihuahuas
  • Dachshunds
  • Italian Greyhounds

They all start to bald around their ears, chest, neck, belly, or thigh in their first-year.

But random patchy hair loss isn’t normal, and allergies can often be the culprit. The hair could be falling out from the reaction or being pulled by excessive licking and scratching.  


Often, sneezing is an indicator of environmental allergies. For example, if they’re inhaling foreign bodies through their nose that don’t belong, they will sneeze to try to naturally get rid of them. This could typically be pollen or grass that’s irritating them. 


As a Shar-Pei pawrent, I learned early on in my journey that there is a distinct difference between throwing up and regurgitation. Throwing up is the actual gut-wrenching process of bringing food back up your tract. It’s painful, it’s noisy, and it’s horrendous. Regurgitation comes from nowhere, and the liquid almost ends up on the floor. Some dogs are prone to regurgitation:

  • Wire Fox Terrier
  • Miniature Schnauzer
  • Great Dane
  • German Shepherd
  • Irish Setter
  • Labrador Retriever
  • Newfoundland
  • Chinese Shar-Pei

Vomiting in a dog isn’t something to overlook. If something your dog has eaten doesn’t agree with them, they’re likely to bring it straight back up painfully. 

Dog allergy 4

What to do next?

Typically, the next step for most dog owners is to go to the vet. But their solution will be to find a cure. But if you don’t know what’s actually wrong, how will you know the right solution?

Instead of an endless cycle, the easy solution is to take an intolerance test. Skip the pills and potions and first get to the root of the problem. Some might argue that tests aren’t 100% accurate.  With blood tests, they would be correct as many factors can affect the results. However, fur tests can be highly accurate and give you a much better idea of what’s wrong than not doing one at all. 

All that’s needed is a small hair sample from your pup and you can have your results in as soon as 48 hours. Swagwags has partnered up with a testing company to help you get the answers you need.

In the meantime, while you wait for your results, it’s worth knowing some of the common dog allergies:

  • Beef (this includes tripe and bones) 
  • Chicken
  • Eggs
  • Dairy
  • Soy
  • Derivatives

These ingredients are found in most dog foods and treats. Just because a brand says it’s organic, hypoallergenic, and all-natural doesn’t make it so. And without knowing your dog’s allergies, it doesn’t make the food right for your dog. For example, Swagwags is hypoallergenic, but George can only have the Super Premium duck and salmon flavours or the grain-free venison. It’s not because there’s anything wrong with the others, he’s just allergic to a lot of ingredients. 

When to seek outside guidance

Our tests work on a traffic light system. Red ingredients you should avoid at all costs as these are the triggers for your doggo’s allergy. Yellow/orange ingredients will end up with some painful and smelly runny poos. And green ingredients will make your pooch one happy dawg. 

Should your test come back with mostly green results, it means various other conditions or infections are likely at play. At this point, it’s essential to consult your vet. For example, Staphylococcal (staph) infections are inflammatory bacterial skin conditions that’ll make your pup itch like mad. Left untreated, the wounds can become fatal. 

Either way, once you know what issues can be harming your pup, you can take steps to eliminate them from their diet or your home. Then, within 4-6 weeks, your dog should start to show signs of increased health.

intolerance tests 2

Don’t take my word for it. One of our clients had the same challenge. With the help of Swagwags and some topical cream, look at how well Reggie improved between June and September! So keep your eyes open for any allergy warning signs and get them tested if you notice any. The more information you have, the easier it’ll be to bring your pooch back to their best.

If your dog is showing any of the symptoms we’ve covered, reach out today to get tested. For only £60 (£100 for two), you can take the first steps towards a healthier, more comfortable life for your pooch. You can contact us here or reach out on Instagram.