Hives on dogs: symptoms, diagnosis and treatment

Hives - also known as urticaria - appear as bumpy, red, and itchy skin. You might notice them when your dog is excessively scratching or you’ve spotted multiple small bumps on your dog’s skin. Lots of things can cause them, like allergies, insect bites, toxins or medication.

Early diagnosis and treatment for hives is essential. Like with hives on humans, they're very uncomfortable, but more importantly, they can signpost something serious, like a severe allergy.

There's a risk hives can worsen and lead to dangerous swelling, respiratory problems and anaphylaxis.

Below, we discuss what hives look like, what causes them and the dog hives treatment options.

Key takeaways - hives in dogs

• What they look like: Hives show up as itchy, red and bumpy skin patches. When treated, they only last a few hours to a few days.

• Signs of hives: Symptoms of hives include excessive itching, swelling and red skin. Small raised bumps may be seen, which can be more obvious in dogs with short coats.

• Allergies play a big role: Hives are commonly caused by allergic reactions, like food or the environment. Less commonly, mental health problems like anxiety can contribute to them too.

• When to seek emergency care: Facial/muzzle swelling (angioedema), difficulty breathing or heavy wheezing, pale gums, vomiting, weakness, or sudden collapse. These are signs of life-threatening anaphylaxis - you must see a vet ASAP.

What are hives, and what do they look like?

Hives simply mean itchy, bumpy skin. The condition is caused by a reaction to something. You'll usually see hives on a dog's face, legs and back, but they can appear pretty much anywhere.

The main issue with hives isn't necessarily the symptoms - it's what the symptoms are telling you. It's the body's way of saying 'Hey - something's up!'

For example, they can mean your dog has a bigger issue, like severe allergies, which will need prompt treatment.

How long do hives last?

Hives typically last from a few hours to two days. But recovery may depend on you removing the trigger or treating the condition.

Here’s a typical hives timeline:

• 0-2 hours: Bumps appear, and your dog starts itching.

• 2-12 hours: Inflammation is at its worst; antihistamines or treatment can provide relief quickly.

• 12-14 hours: Bumps begin to flatten as the allergen clears.

• 48+ hours: If treated and/or the allergen is removed, hives will go away. If they’re lingering, it’s likely something else causing it.

Symptoms of hives on dogs

You'll see things like:

• A patchy, bumpy coat - most obvious in dogs with short coats

• Excessive itching

• Red skin

• Swelling (Angioedema)

The hives vary in size; they can range from just one or two centimetres to several centimetres in length. You may see them in one localised area, or they may be spread around the body. You’re likely to spot the localised, clustered hives more easily.

An itchy dog can mean many things, though. So never just assume it's hives. It can mean other irritants, like fleas or a skin infection, are causing the symptoms.

That’s why we always recommend speaking to your vet if you're concerned.

Causes of hives in dogs

As mentioned, hives are normally a reaction to something your dog has come into contact with or eaten.

Allergic reactions

Allergies are the number-one reason for hives. These can include allergies due to:

• Food

• Environment (pollen, dust mites, etc.)

• Insect bites and stings

When your dog encounters an allergen, their immune system releases histamines, which cause knock-on effects, creating the itchy, raised bumps on your dog’s skin.

Allergy treatment usually starts with a process of elimination. It begins with finding the allergen and then using a combination of treatment and lifestyle changes to limit your dog's chances of encountering said allergen.

While you and your vet investigate, they can prescribe things to manage the symptoms.

Our article on allergies in pets may be helpful.

Medications and vaccinations

The side effects from common medications and vaccinations can sometimes result in hives in rare cases. Always talk to your vet if this happens after your dog has been given any medication.

Do note, however, that vaccinations are safe, and your vet should chat through the common side effects of medication with you.

When in doubt, always read the documents that come with your pet's medication, especially the parts on side effects, and ask your vet if you have any questions or concerns.

Other triggers

Hives can occasionally mean something else is going on; it's not just a reaction to outside stimulants, and your pet's mental health or behaviour can play a part.

Existing hives or reactions can be made worse by stress. So an anxious dog with skin issues may have a more exaggerated response to triggers.

Diagnosing hives

It's easy to diagnose hives. As mentioned, the symptoms are very distinct.

But finding the cause of hives can be difficult. A vet won't just look at and treat the hives when you bring your dog into the clinic; they'll look at your pet holistically to try and determine what could be causing this problem.

Sometimes, it's part of a dog's ongoing allergic skin disease and may be an acute reaction to something, but other times, it can mean something else. It may also be a one-off reaction, like an insect bite or sting. It’s not always possible to identify the cause for certain in these cases, unless you saw the offending insect on your pet.

Your vet will start with a physical examination, ruling out severe reactions like anaphylactic shock. They'll then ask for some background on your dog, like diet and medication, and if they have come into contact with anything different around the time the hives appeared.

Following that, they may perform an allergy test and blood tests to pinpoint what exactly is causing the hives, especially if this is a recurrent issue.

Dog hives treatment and management

If your vet suspects a food allergy, they may perform an allergy test and prescribe an elimination diet. Elimination diets can get tricky, so you’ll need to make sure you follow your vet’s advice on which prescription diets are safe and suitable for your pet.

You’ll need to be strict at home to make sure your dog doesn’t eat anything else while on the trial, including treats or table scraps. If successful, your dog might need a special diet for the rest of their life.

Some environmental allergens are tricky to pinpoint and can take longer to find. It can also be impossible to avoid some environmental allergens, like pollen.

Allergy testing is useful for many environmental allergens but sometimes no cause is found.

In cases where the owner can't remove the trigger, the vet may prescribe:

• Antihistamines or other allergy medications

• Cold compresses to reduce itching and heat

• Corticosteroids (a type of anti-inflammatory)

• EpiPen in rare cases if reactions are severe

• Immunotherapy can be useful for environmental allergens, where low doses of allergens are given by regular injections, to desensitise pets

For at-home hives recipes, we recommend:

• Aloe vera - just remember aloe vera is toxic to dogs if ingested, and only use 100% pure pet-safe aloe vera gel.

• Oatmeal baths

How to give an oatmeal bath for a dog with hives

Rolled oats can help make a nice soothing bath for itchy dogs. Here's how:

1. Pour a cup of rolled oats into an old nylon stocking and tie a knot in the end.

2. Run a warm bath over the netted oats and then leave the water to cool down to body temperature or lower. Make sure the bath water isn’t too deep.

3. Introduce your dog to the water and use a small jug to gently pour it over his body, for about 5-10 minutes.

4. Remove your dog from the bath and towel dry them

Alternatively, you could try a commercial oat-based dog shampoo. Just take care that you aren’t accidentally diluting any spot-on flea products or other prescribed topical medications by bathing your dog.

Always speak to your vet before using any home remedies on your pet.

How long does treatment take to work?

Veterinary prescribed treatment usually starts working within minutes, and it often only takes a few days to clear up.

Sometimes, if it’s severe, it can take around three days. If it persists, go back and see your vet - there may be something deeper going on.

When to seek veterinary care

There are two clear-cut cases where you need to seek urgent veterinary care. While hives are generally minor, you should escalate to a professional if:

• They're persistent or severe

• Your dog shows signs of anaphylaxis

Anaphylaxis, or an anaphylactic reaction, is very serious and life-threatening. The symptoms are:

• Collapse

• Convulsions and shaking

• Diarrhoea and vomiting

• Difficult breathing

• Pale gums/mucous membranes

• Severe, sudden rashes

• Swelling, especially facial swelling

• Unsteady walking

Go to your vet immediately if your dog is having an anaphylactic reaction.

Preventive measures

Identifying and avoiding triggers

Your vet can help you find the trigger for hives. But, as mentioned, they can't always find what might cause them, especially if it's chemical or environmental. Managing and treating hives and allergies can be a long-term project.

You can help identify and avoid triggers with a few long-term steps, like:

• Keeping a journal of potential allergens - note everything your dog eats, and check to see if hives appear after certain activities, like walking in long grass or when the house is dusty.

• Regularly cleaning your dog's environment - a clean environment is a good proactive step to reduce the number of potential allergens.

• The right diet - continue to feed your dog a consistent, suitable diet and note any symptoms if you feed anything different.

Our article on pet nutrition can help.

Regular veterinary check-ups

Finding the signs of hives early is essential. Sometimes, your vet can see these in their very early stages as part of routine health checks.

That's why preventative pet care should be top of the list.

Strengthening the immune system

A balanced, commercially prepared diet, regular exercise and stress management can all increase your dog's general health. Whilst they won’t stop your dog from getting hives, they're an important part of maintaining your pet's long-term health.

Remember though: it's never a replacement for proper medication, treatment, and veterinary advice.

Conditions that look like hives (but aren’t hives)

Things that look like hives to the untrained eye but aren’t include:

• Allergic dermatitis

• Contact dermatitis

• Pyoderma (bacterial skin infection)

• Fleas, mites and other nasties

• Folliculitis or ringworm

Essentially: if your dog has had red, raised bumps or a skin rash that’s been there for more than two days, it may not be hives.

It’s why seeing a vet is important.

How dog insurance helps hives

Overall, hives in dogs aren't usually a serious condition in isolation. But it can sometimes mean a deeper, serious problem is present.

Always chat with your vet as it's the most important step to rule out and treat underlying causes.

Of course, dog insurance can help treat conditions like this, and can help you and your four-legged friend prepare.