Hives on dogs: lumps, bumps and swelling
Hives are raised, itchy welts caused by an allergic reaction, and they often come up fast — within minutes to hours of whatever triggered them. Most cases settle with treatment, but a swollen face or any sign of breathing difficulty needs a vet immediately.
Get this seen
This is worth a call to your vet rather than waiting to see how it goes, particularly if it has lasted more than a day or your pet is otherwise off-colour.
When it is an emergency
Swelling of the face, muzzle, eyes or throat, any difficulty breathing, vomiting alongside the hives, weakness or collapse — ring a vet straight away. A reaction that involves the airway can worsen quickly.
A reaction shortly after a vaccination, an insect sting, or a new medication is worth ringing about even if the dog seems comfortable, because the vet will want to know and may want to see them.
Do not give human antihistamines without veterinary advice. Doses are not interchangeable, several human formulations contain additional ingredients that are unsafe for dogs, and the wrong product does real harm.
What causes them
Insect stings and bites are among the most common triggers, especially in spring and summer and in dogs who chase bees.
Plants, chemicals and contact irritants — a new cleaning product, a treated lawn, a plant brushed against on a walk.
Food and medication reactions are both possible, and vaccination occasionally produces a mild reaction that resolves quickly.
In many cases the trigger is never identified, which is frustrating but does not usually change the treatment.
What to do
Photograph the hives when you see them. They often fade before the appointment, and a photo saves the vet guessing.
Note what changed in the last few hours — new food or treat, a walk somewhere different, a new product used in the house, any medication or a recent vaccination.
Keep the dog cool and calm; heat and excitement make itching worse. Stop them scratching or rubbing the area where you can, since broken skin invites a secondary infection.
A cool rinse can be soothing if the skin is intact, but do not apply creams, ointments or human treatments without asking your vet first.
What can help
Things we stock that owners commonly use alongside a vet’s advice — not a substitute for it.
MPS Head Cover — Breathable Dog Head & Ear Protector
A comfortable, breathable alternative to the cone of shame — protects head and ear wounds or bandages while letting your dog move freely.
From£5.99
Leucillin Antiseptic Skincare Spray for Cats & Dogs
A versatile, alcohol-free antiseptic spray that cleans, soothes, and helps protect your pet's skin from bacteria, viruses, and fungi.
From£7.99
Absorbent Cotton Gauze Swabs for Pets – Pack of 100
Highly absorbent, low-lint cotton gauze swabs produced in clean conditions — a practical first-aid essential available in three size and ply combinations.
From£4.49
Wahl Competition Series Clipper Blades
High-precision, chrome-plated clipper blades with a rust-resistant finish, available in 17 sizes for every coat type and clipping style.
From£37.99
Common questions
- How long do hives last on a dog?
- With treatment they often settle within a day or so. Hives that keep returning, or that are still present after a couple of days, need a vet visit to work out why.
- Can I give my dog Piriton for hives?
- Not without veterinary advice. Doses are not interchangeable with human ones, and several human antihistamine products contain additional ingredients that are unsafe for dogs.
- When are dog hives an emergency?
- Swelling of the face, muzzle, eyes or throat, any breathing difficulty, vomiting, weakness or collapse. Ring a vet immediately, as airway involvement can worsen fast.
- What causes hives in dogs?
- Insect stings, plants, contact irritants, foods, medications and occasionally vaccinations. In many cases the trigger is never identified, which does not usually change treatment.
- Should I photograph my dog’s hives?
- Yes. They often fade before the appointment, and a clear photo is far more useful to a vet than a description of something that is no longer visible.
Related
Sources
Written against guidance published by UK veterinary and welfare organisations. Always confirm specifics with your own vet.
Written by Matt Garnett, who runs Giddy Pets and is a lifelong pet owner — not a vet. This is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your animal. How we write these guides.