Updated: Sep 22
Oh, pup — what have you gotten yourself into this time? If your dog suddenly develops raised, swollen bumps on their skin, you’re probably wondering: Why does my dog have hives - and is this an emergency?
Hives in dogs (also called urticaria) are raised welts caused by an allergic reaction. They can vary in size and typically appear and disappear quickly - causing itchy discomfort to your pet. Mild cases only affect the skin, but severe allergic reactions can progress quickly. A reaction in dogs can shift from mild to severe in a short period of time, so when in doubt, call VEG ER For Pets immediately.
Here’s how to tell the difference between mild and severe - and when to seek emergency veterinary care.
What do hives look like on dogs?
Hives typically appear suddenly - often within minutes to hours of exposure to a trigger.
Red, swollen welts
These raised bumps or welts can appear anywhere on your dog’s body and vary in size.
Sudden swelling under the fur
Hives can cause swelling around the eyes, ears, and muzzle.
In short-haired dogs, you may see red, puffy patches. In thick-coated dogs, hives are often easier to feel than see. Your dog may frequently scratch or bite at the affected areas, or pant excessively due to discomfort and anxiety.
Why does my dog suddenly have hives?
Hives in dogs can be triggered by many different factors. And when your dog BFF feels itchy and uncomfortable, you want to find the reason immediately.
Insect bites or stings. Bites from fleas, ants, or mosquitos and stings from bees or wasps can cause hives in dogs.
New medications. Some dogs may develop hives as a reaction to specific medications.
Vaccines. Occasionally, vaccinations can cause an allergic reaction which may result in hives.
Food allergies. Certain ingredients in your dog’s diet may cause an allergic reaction.
Environmental allergens. Pollen, mold, dust mites, and other environmental factors can trigger hives.
Heat or sun exposure. Overexposure to sunlight or high temperatures can cause hives in some dogs.
Stress. Just like their people friends, dogs can develop hives due to stress or anxiety.
Pressure or friction. Ill-fitting collars or harnesses can cause hives. Be sure the collar or harness you use on your dog is not too tight, as too much pressure can cause skin irritation or hives. Conversely, collars and harnesses that are too loose can rub the skin, and create friction that can lead to hives.
Grooming tools. Just like people can get razor burn, a dog can get clipper burn. If a dog groomer’s clipper is too sharp or too dull, it can cause irritation to your dog’s skin. Your pup could even be allergic to the clipper itself, as certain metals can cause an allergic reaction of red bumps.
Underlying health issues. In rare cases, hives may signal a more serious condition like an autoimmune disorder or infection. Keep an eye on your dog and consult your primary care vet to rule out serious health problems.
Sometimes the trigger for dog hives isn’t obvious. Even a quick outdoor walk can result in an insect sting or environmental reaction in dogs. What matters most is watching for signs that the reaction is progressing.
What to do if your dog has hives
If your dog develops hives, here are some steps you can take to keep your pooch comfortable while you wait for further guidance from your primary care vet:
Place cool compresses. Gently apply cool, damp cloths to the affected areas to soothe itching and reduce swelling. Avoid placing ice directly on your dog’s skin.
Stay calm. Keep your dog in a calm, stress-free environment, as anxiety can make the symptoms worse.
Avoid scratching. Discourage your dog from itching or biting the hives, as this can cause further irritation or infection. If needed, use an Elizabethan dog collar to prevent your dog from scratching their hives.
Remember, seeking professional care from a vet ensures that your dog gets a proper evaluation and the right treatment. It's always best to seek veterinary care because hives can quickly lead to facial swelling, trouble breathing, and an anaphylactic reaction.
Can I give my dog Benadryl?
While diphenhydramine (Benadryl) is sometimes used in dogs, it is NOT universally safe for every dog and must be dosed carefully by a vet based on weight and medical history.
Some over-the-counter allergy medications also contain additional ingredients (like decongestants or xylitol) that are dangerous for dogs. Do not give your pup any medication unless a veterinarian specifically instructs you to do so.
When hives in dogs become an emergency
Although hives can go away on their own, you should seek veterinary care quickly to make sure the hives do not get worse or your pet does not have a more severe allergic reaction. However, if any of the following symptoms associated with dog hives appear, bring your dog to your nearest VEG immediately:
Most mild hives are uncomfortable but not life-threatening. However, hives can also be an early sign of anaphylaxis in dogs, a severe, body-wide allergic reaction. If your dog’s face is swollen and they’re struggling to breathe, this is an emergency - it’s imperative that you seek emergency veterinary care to make sure your dog’s condition doesn’t worsen.
Vet treatment for dog hives
Once your primary care vet diagnoses the cause of your dog’s hives, they can recommend appropriate treatments. Do not take it upon yourself to treat your dog’s hives. The veterinary team will evaluate your pup’s airway and breathing, monitor for signs of shock, and check heart rate, gum color, and blood pressure. Treatment may include:
Antihistamines. Medications that can help reduce allergic reactions.
Corticosteroids. In severe cases, steroids may be prescribed to reduce inflammation and itching.
Topical treatments. Your vet can let you know which ointments or sprays might help soothe the affected areas.
IV fluids. These can help stabilize blood pressure and support circulation.
Oxygen therapy. Provides respiratory support if swelling or anaphylaxis affects your dog’s ability to breathe comfortably.
Some dogs need observation because allergic reactions can flare in waves. Even if swelling improves initially, delayed symptoms can occur.
How fast do dog hives go away, and can they come back?
Mild hives can resolve within a few hours. More significant allergic reactions may require treatment and monitoring. The key factor isn’t how dramatic the bumps look - it’s whether your dog is stable. If your dog is alert and responsive, breathing comfortably, and not vomiting or lethargic, you may be able to monitor after speaking with a veterinarian.
Unfortunately for your poor pup, some allergic reactions in dogs can come back after initial improvement. But the good news is that identifying and avoiding the allergen or trigger can help prevent future occurrences of hives in your dog. To help reduce your dog’s risk of hives, consider these tips:
Monitor your dog. Keep a close eye on your dog's environment and behavior. Regularly monitor their diet, exposure to potential allergens, and reactions to new food, products, or medications.
Manage your dog’s allergies. If your dog has known allergies, work with your primary care vet to create a management plan. This may involve a special diet, reducing environmental allergens through regular cleaning and air filtration, or using prescribed medications.
Safeguard your dog’s outdoor activities. Your doggo loves the great outdoors? Great! Just make sure outdoor time is a safe time. Avoid areas where insect bites or excessive sun exposure is likely. Use dog-safe insect repellents and sunscreens, as needed.
When in doubt - call VEG
Allergic reactions can be unpredictable. What starts as a few raised bumps can progress quickly in some dogs. If your dog has sudden hives, facial swelling, or signs of an allergic reaction, don’t wait to see what happens.
The emergency veterinarians at VEG are equipped to treat severe allergic reactions, airway swelling, and anaphylaxis - and early intervention can make all the difference in getting your dog back to their happy care-free self.
