How do you treat an allergic reaction on a dog

By Isabella Storyclaire

last updated September 16, 2024

Contributions sourced from

Types of Dog Allergies and How to Treat Them

Have you heard someone tell you that their dog has allergies? Has your veterinarian suggested that allergies could be a problem for your dog? Do you suspect that your dog has allergies? If so, then youve probably realized that allergies in dogs are not quite as simple as we might wish. For starters, there are several different types of allergies that could be causing your dogs symptoms.

Allergies are a misguided reaction to foreign substances by the bodys immune system, which, of course, people and pets can suffer from. There are quite a few different types of allergies in dogs. Skin allergies, food allergies, and environmental allergens all pose challenges for dogs and their owners, and to make things more complicated, the symptoms of all these different types of allergies can overlap.

Symptoms of Allergies in Dogs

The symptoms of allergies in dogs may vary depending on the cause. A dog that goes into anaphylactic shock, for instance, will have a drop in blood pressure followed by shock, which is very different from a skin condition.

In general, however, the following symptoms could be a sign of an allergic reaction.

Itchiness
Hives
Swelling of the face, ears, lips, eyelids, or earflaps
Red, inflamed skin
Diarrhea
Vomiting
Sneezing
Itchy ears
Chronic ear infections
Itchy, runny eyes
Constant licking

Some of these symptoms could also be a sign of another condition. Make an appointment with your veterinarian if you notice changes in their behavior to get an accurate diagnosis.

Types of Allergic Reactions in Dogs

Allergic Dermatitis in Dogs

Skin allergies in dogs, known as allergic dermatitis, is the most common type of allergic reaction in dogs. Skin allergies in dogs are mainly caused by one of three things: fleas, food allergies, and atopicor environmentalallergies.Flea allergy dermatitis is an allergic reaction to fleabites, and some dogs are allergic to flea saliva, which can cause their skin to become red, inflamed, or scabbed because their skin will feel extremely itchy. Its the easiest type of allergic dermatitis to treat, since you can apply flea medication for dogs to help heal their skin.

Another cause of skin allergy in dogs is from food allergies and sensitivities. Just like humans can be allergic to certain foods or ingredients, dogs can be allergic, which can cause itchy skin. Dogs with food allergies usually have itchy ears or paws, sometimes along with gastrointestinal symptoms. Dr. Klein, Chief Veterinary Officer for the AKC, says that food allergies are not as common as you might think. True food allergies result in an immune response, which can range in symptoms from hives, facial swelling, and itchiness to gastrointestinal signs like vomiting and diarrhea or a combination of both.

Environmental allergens can also affect the skin and be the cause of allergic dermatitis. Things like dust, pollen, fungus, and mold can cause these reactions, but in most cases, these allergies are seasonal. As with food allergies that affect the skin, the most commonly affected areas are the paws and ears (but also include the wrists, ankles, muzzle, underarms, groin, around the eyes, and in between the toes).

All skin allergies pose the risk of secondary infection. As your dog scratches, bites, and licks at his skin, he risks opening up his skin to yeast and bacterial infections that may require treatment.

Urticaria, or Hives, in Dogs

Also known as urticaria, hives on dogs are very itchy but are not life-threatening. Hives appear as a reaction anywhere from 6 to 24 hours after exposure to allergens. This consists of itchy, swelled skin, that usually looks like a red rash. Its easiest to spot hives on dogs that are hairless or have short coats. Dogs with longer hair can get them too, but its more likely that youd be able to fee the hives rather than see them. Your vet will prescribe an antihistamine in order to treat urticaria in dogs.

Edema of Face or Throat

Swelling of the throat or face looks severe, but its actually almost never fatal. This area of swelling, which can also include swelling of the eyelids or ear flaps, is known as angioneurotic edema. Its actually pretty easily treated, and despite how it looks, its a good sign in terms of allergic reactions.

If your dog has edema of any of these areas, the time for a fatal allergic reaction has most likely passed, and they arent in as much danger. Angioneurotic edema occurs anywhere from 30 minutes to a few hours after exposure to an allergen, and can also come with hives.A veterinarian will often give dogs with this reaction an antihistamine injection. Untreated, it may take a day or two for the swelling to subside.

Anaphylactic Shock

Perhaps the most alarming of all the types of allergic reactions in dogs is anaphylactic shock. Like people, dogs can go into anaphylactic shock if they have a severe reaction to an allergen. This happens when antibodies produced by the host react negatively to the allergen, dropping your dogs blood pressure rapidly and sending them into shock. This can be fatal if not treated, but luckily, anaphylactic reactions are rare in dogs.

This can be a response to any allergen, most commonly bee or wasp stings, or vaccine reactions. Because of this, your vet will always recommend keeping a close eye on your dog after theyve been given any new vaccine, drug, or food item, as they might be allergic.

If a dog has had a past incident and survived, the owner may carry an epipen, but sometimes the first occurrence can lead to death. Fortunately these reactions are very rare in dogs.

In some rare cases, a severe food allergy reaction resulting in anaphylaxis can occur, similar to severe peanut allergies in humans. The best way to diagnose and treat a food allergy is to work with your veterinarian to manage your dogs symptoms and discover the ingredient causing the reaction.

Diagnosing Allergies in Dogs

Flea allergy dermatitis is typically the easiest allergy to diagnose. It is usually diagnosed by identifying fleas on your dogs body and applying a product that kills fleas before they can bite to see if that solves the issues.

The first thing your veterinarian will do in allergy testing is rule out any other condition that could be causing your dogs symptoms. If your veterinarian feels that an allergy is a likely cause, they may propose allergy testing to try and determine the cause of the allergen that is causing the reaction. However, keep in mind it may not always be possible to determine the cause of an allergy with testing.

If you have ever undergone allergy testing, then you know that diagnosing allergies is often complicated. Its the same for dogs, but its worth it to understand what to stay away from when it comes to your dog.Food allergies are often diagnosed using an elimination diet. A food trial consists of feeding a dog one source of protein and carbohydrate for 12 weeks.

Treating Allergies in Dogs

The best way to treat an allergy is avoidance of the cause and allergen, which may not always be possible. They type of treatment depends on the type of allergy your dog has. For example, the best way to treat flea allergy dermatitis is to kill the fleas, whereas the best way to treat a food allergy or food intolerance is a change in diet.

Depending on the cause and severity of your dogs allergic reaction, your veterinarian will prescribe different things. For hives, they might suggest antihistamines, cortisones, medicated shampoos, whereas with food allergies they might suggest fish oil or other Omega-3 fatty acid supplements. For skin allergies, they might prescribe dog-safe anti-inflammatory wipes or shampoo on skin to provide irritation relief.

In addition to any lifestyle changes that might be necessary, your veterinarian may also prescribe an allergy relief medication for your dog that will help control the signs associated with the allergic reaction, such as itching and any secondary skin infections that might have developed as a result of the irritant.

If your dog has a severe allergic reaction, your best course of action is to get them to an emergency veterinary hospital as quickly as possible.

Allergic reactions in dogs

Types of reaction

Bee stings

Most dogs stung by a bee, or another insect, develop redness, pain, and swelling around the site, but recover well (on their own, or with the help of an antihistamine medication). However, just like us, some dogs are allergic to insect stings and suffer much more serious symptoms. Call your vet for advice if an insect has stung your dog.

Medication and vaccine reactions

Although its extremely rare, just like us, some dogs are allergic to certain medicines and vaccinations. Fortunately, most medication and vaccinationreactions are mild, for example developing itchy skin after a flea treatment, or feeling slightly off-colour after a vaccination. However, severe reactions do sometimes happen and cause serious symptoms that require immediate veterinary attention.

Fleas, food, pollen and other allergic skin disease

Allergic skin disease (often caused by fleas, food and/or pollen) is a different type of allergy that causes a low-level, ongoing problem, (not a sudden, acute reaction). Follow the link for more information.

Does Your Dog Have a Flea Allergy?

What Is Flea Allergy Dermatitis in Dogs?

Fleas take their first blood meal on the host (your dog) within minutes of contact.² When a flea feeds, it injects its saliva into your dogs skin. This saliva contains enzymes, peptides, and amino acids. It also contains histamine-like compounds that trigger a release from the dogs immune system.

Flea saliva can cause an inflammatory reaction in animals that are sensitive to it. Some dogs have an immediate hypersensitivity to it within 15 minutes, while others have a delayed reaction that takes 24-48 hours.

Dogs with atopic dermatitis are more likely predisposed to developing flea allergy dermatitis (FAD).¹

What if I Dont See Fleas on My Dog?

Just because you dont see the fleas, it does not mean they arent there.

A common misconception is that fleas are only a concern during warmer months. This is not true. Another misconception is that fleas cant come inside your house. Fleas can live indoors as eggs, larvae, and pupae, and pets and humans can also bring fleas inside.

Signs of a Flea Allergy in Dogs

You may not see the fleas right away, but you will see the evidence of the allergic reaction. Even one flea bite can cause this allergic reaction.

When dogs feel flea bites, they often chew and bite at their rear by their tail and/or jump up from a resting position. If you see itching in your dog, and it leads to hair loss on the middle of the back to the tail base, you need to think flea allergy dermatitis. The hair loss can spread all over the body, up to the head and neck if left untreated.

When a dog scratches, licks, and chews, it breaks the skin barrier and can cause open sores and scabs. The licking and chewing can also cause ongoing moisture that can lead to yeast and bacterial infections.

Photo By: Sandra Mitchell, DVM

How Does the Vet Diagnose a Flea Allergy in Dogs?

It is important to get a true diagnosis when a dog is itching severely.

Your vet will first look for any evidence of fleas or flea dirt (which is the flea excrement), sometimes using a fine-tooth comb.

It is common that a pet parent may not see the fleas at home on the pet, but veterinary staff are trained flea detectives who work hard to find them.

Tests can also be done to determine the underlying cause of the allergic reaction. Vets use blood tests and skin tests for flea allergies.

Skin testing, called intradermal testing, is usually performed by a veterinary dermatologist. A wheal (bump on the skin) forms on the skin, usually within 15-20 minutes of injected a small amount of an allergen into the skin.3

Blood testing can also be done in most general veterinary practices to test the IgE directed against the flea-specific salivary antigens.

Diagnosing the Secondary Skin Infections in Dogs

There is often a secondary infection that develops on a dogs skin with FAD. Your vet can use cytology to diagnose any secondary skin infections.

Cutaneous cytology is a valuable diagnostic tool. Using a piece of tape to collect a surface sample from a skin lesion helps determine the type of microbial population as well as the inflammatory component present.⁴

It is quick and inexpensive. This helps guide the doctor to prescribe the most appropriate and effective treatment for the patient.

How Do You Treat Flea Allergy Dermatitis in Dogs?

The number one priority in FAD treatment is to kill the fleas! This means to kill them not only on your dog, but on all pets in the household and killing fleas in the environment.

Oral Flea Medications

Oral flea medications are going to provide the quickest demise of the fleas.

You can use a product containing Spinosad to kill all fleas on your dog within 30-60 minutes to give the quickest relief. Then you can follow up with a product that lasts 30-90 days.

Once the fleas are dead, it is a good idea to bathe the dog to get off all of the dead bugs and their excrement. You can get a medicated shampoo prescribed by your vet to soothe the skin, or you can find over-the-counter dog shampoos that contain oatmeal and pramoxine to help soothe the itch.

Skin Treatment

After the fleas are eradicated, you still need to treat the skin irritation caused by the allergic dermatitis.

In mild cases, you can treat your dog with Benadryl at home to stop the allergic reaction and provide relief from the itch.

Always check with your veterinarian for dosing instructions and to make sure this medication is safe for your pet.

Most dogs with FAD need more help, and you can talk to your veterinarian about the need for steroids or other allergy meds such as Apoquel or Cytopoint.

How to Prevent Flea Allergies in Dogs

As the saying goes, an ounce of prevention goes a long way. Preventing, reducing, and eliminating flea infestations is crucial to preventing recurring FAD.

Treat the Environment

Just treating your pet without treating the environment is only 50% of the problem. Indoor flea eradication measures include vacuuming (carpets, cushioned furniture, cracks and crevices on floors, and baseboards) and washing pet bedding in hot soapy water.

Treat Your Yard

Outdoor areas need attention, such as shaded areas around the house or your dogs kennel or favorite sleeping area. You can use premise sprays for fleas indoors and out. For both the house and yard, you may need to contact an exterminator for the best method of flea removal.

Use Monthly Flea and Tick Preventatives

There are many flea prevention products on the market. Work with your veterinarian to pick the one that is best for your dog.

The oral medications in the isoxazoline category have been the most recent group that has been extremely effective and safe for most dogs. Talk to your vet to make sure your dog doesnt have any contraindications such as seizures.

If you keep the flea population under control, you can spare your pet pain and suffering. It can take three months to rid your house of an infestation. It is time-consuming and expensive.

Prevent what you can to keep your dog flea-free!