Anaphylaxis in Dogs: Signs and Treatment

Anaphylactic shock in dogs is, thankfully, rare. It is a life-threatening reaction that can progress rapidly over minutes. Triggers can include foods, insect venom, or medicines, including vaccinations.

Recognising the symptoms is essential so that treatment can be sought immediately. With a prompt response, signs can be quickly reversed.

As anaphylaxis can be fatal if not quickly treated, it is something that we always take very seriously.

What is Anaphylaxis in Dogs?

Anaphylaxis is a sudden and severe allergic reaction. It is an immune response to something that the body thinks it is ‘under attack’ from.

The dramatic release of histamine leads to reduced blood flow to the heart and decreased oxygen delivery to the heart.

The liver and gastrointestinal tract are the ‘shock organs’ in dogs. Conversely, the lungs are the ‘shock organs’ in cats, so they react with narrowed airways and difficulty breathing.

What Are Common Causes of Anaphylaxis in Dogs?

There is a range of potential triggers, and some dogs may be allergic to more than one thing.

Insect Stings and Bites

The most common insects we think of in the UK, when it comes to canine anaphylaxis, are the bee and the wasp. Other culprits include hornets and ants.

Food Allergies

Usually, when we say a dog has a food allergy, we are talking about a non-IgE allergy that causes signs like itchy skin and diarrhoea.

However, very rarely, a dog may have an anaphylactic allergy to an ingredient like milk, peanut or beef.

This is different to a toxic food, such as chocolate or onions. These foods are poisonous to all dogs, not just a small number.

Medications and Vaccines

Sudden reactions to medicines like antibiotics and vaccines are also possible. Sometimes, the reaction is to the adjuvant within the vaccine, rather than the active ingredient.

While anaphylaxis can occur at the first exposure, it is often seen the second time the animal receives the drug.

What Are Signs of Anaphylaxis in Dogs?

As signs are dramatic and progress rapidly, they are hard to miss.

Early Warning Signs to Watch for

Initially, your dog may be acting lethargic, quiet or unsteady. You may notice that they start to develop skin swelling or hives and seem itchy.

Drooling, vomiting (which may be bloody), and diarrhoea are not uncommon and can be profuse.

Severe and Life-Threatening Symptoms

As the reaction progresses, blood circulation volume decreases, and dogs may collapse. They can experience difficulty breathing and blue or grey mucous membranes.

How Quickly Symptoms Can Appear

For most, symptoms are going to begin within minutes of contact with the trigger. Delayed reactions are possible but less common.

Is Anaphylaxis in Dogs an Emergency?

There is no doubt that anaphylaxis is always a true emergency.

When to Seek Immediate Veterinary Care

If you suspect your dog is experiencing signs of anaphylaxis or if they’ve had a previous episode and have had exposure to their trigger, contact an emergency vet right away.

What Can Happen if Anaphylaxis Is Left Untreated

Without intervention, dogs that go into anaphylactic shock can suffer with hypoxia (low blood oxygen levels) and their heart are no longer able to pump sufficient blood volume. This can quickly lead to organ failure and death.

Related emergencies to be aware of

There are other medical emergencies that may present similarly to anaphylaxis, which can be confusing.

Some other considerations include heat stroke, toxin exposure, GDV, an asthmatic flare-up, a vasovagal event, or an episode of acutely low blood sugar.

What Should You Do If You Suspect Anaphylaxis in Your Dog?

At the first suspicion of anaphylaxis, call your closest open vet clinic and start transporting your dog there. This is a condition where time is of the essence.

Immediate Steps to Take at Home

Initially, remove any potential trigger. For example, if your dog has been eating something, take it away before more can be ingested. If they’ve been stung, carefully remove the stinger using the credit card method.

Consider giving a dose of canine safe antihistamine, as long as your dog is coping well and not vomiting or collapsed.

What Not to Do During an Anaphylactic Reaction

Do not attempt to induce vomiting. This is true even if your dog has ingested something they are allergic to; trying to make them sick afterwards will not help.

How to Transport Your Dog Safely to the Vet

To help your dog cope with the shock, it is best if your dog is lying down; encourage this as much as possible. Try to keep them at a comfortable temperature, still and calm.

If your dog is too heavy to carry to the car, it may help to have them lying on a duvet, and to carry them with one person on each side of them.

How Vets Diagnose Anaphylaxis in Dogs

Much of the diagnosis will be based on the dog’s recent history and the vet’s clinical suspicion.

Physical Examination and Symptom History

Your vet will be on the lookout for several criteria, including low blood pressure, skin involvement, a change in breathing and/or gastrointestinal signs.

Ruling Out Other Emergencies

It can be difficult to definitively rule out other medical causes initially, but this can be done with screening tests, including patient-side blood tests, temperature checks, and possibly chest and/or abdominal imaging.

What Are Treatment Options for Anaphylaxis in Dogs?

The goal is to stabilise the patient rapidly and to counteract the shock. Airways, breathing, and circulation are the focus.

Emergency Medications Used by Vets

Injectable adrenaline is the mainstay of therapy for those presenting in anaphylactic shock. Patients often also receive antihistamines, bronchodilators if they are wheezing, and/or steroids.

Supportive Care and Monitoring

Fluid therapy is commonly provided to increase blood pressure when needed. Those with hypoxia can be given oxygen via a facemask. If the patient needs to be intubated, the oxygen would be delivered through their ET tube.

As patients may experience ongoing symptoms or biphasic reactions (a further anaphylactic event several hours after the initial episode), they will be kept in the clinic and monitored until fully recovered.

Recovery Time and Prognosis

For those who respond to therapy, recovery is rapid, and prognosis is excellent. However, owners must be aware that there is a possibility of death if treatment is not begun rapidly.

What Are Possible Complications After Anaphylaxis?

For most patients, once the anaphylactic episode has been treated, they make a full recovery.

Organ Damage and Shock

If a dog has been seriously unwell and experienced prolonged shock or episodes of very low oxygen, there is the potential for permanent organ damage.

Ongoing Allergic Sensitivity

Dogs will likely remain allergic to their trigger, requiring ongoing vigilance on the part of the owner.

How to Prevent Anaphylaxis in Dogs

It is not always going to be possible to prevent an anaphylactic episode, especially the first one, which will occur out of the blue.

Avoiding Known Triggers

If you know your dog reacts to certain triggers, you must diligently avoid them. Always make your vet aware of any previous reaction to a medicine or vaccine. If outside, keep your dog away from bees or wasps, or bring them back indoors.

Managing Dogs With Known Allergies

For those pets who have had very severe or life-threatening reactions in the past, discuss with your vet if it may be appropriate to carry a vial of adrenaline and needle, or an EpiPen.

Ensure you know your vet’s out-of-hours details, and find out where the nearest emergency clinic is whenever you are travelling with your dog.

If your pet is being looked after by someone else, be sure to discuss their allergic triggers and how to recognise a reaction.

Get Emergency Vet Care for Your Dog

Contact us whenever you need us, if you require emergency vet care and suspect your dog may be having a serious allergic reaction.

What Are the Signs of Anaphylaxis in Dogs?

Signs of anaphylaxis can appear suddenly and may include facial swelling, hives, vomiting, diarrhoea, difficulty breathing, weakness, pale gums, or collapse. Some dogs show restlessness or excessive drooling. Because anaphylaxis is life-threatening and progresses quickly, immediate veterinary care is essential.

How is Anaphylaxis Diagnosed in Dogs?

Diagnosis is usually based on the sudden onset of symptoms and recent exposure to a trigger, such as insect stings, food, medication, or vaccines. Vets assess clinical signs, medical history, and response to emergency treatment. Blood tests or additional investigations may be used later to identify underlying allergies or rule out other conditions.

What Should I Do If My Dog Has an Allergic Reaction?

Seek veterinary care immediately, especially if symptoms are severe or worsening. Keep your dog calm, remove any known trigger if safe, and monitor breathing and gum colour. Do not give human medications unless advised by a vet. Rapid treatment greatly improves outcomes.

Are Certain Breeds More Susceptible to Anaphylaxis?

Any dog can experience anaphylaxis, but some breeds may be more prone to allergic conditions overall, including Labrador Retrievers, Golden Retrievers, Boxers, and Bulldogs. Individual sensitivity varies, so previous allergic reactions are a stronger predictor than breed alone. Regular vet guidance helps manage risk.