Mosquito Bite Allergies in Dogs

Although bees and wasps are the most commonly blamed insects when it comes to allergic reactions, mosquitos cause their fair share of allergy symptoms for both humans and canines. Most bites by the mosquito cause at least a small allergic reaction to the mosquito’s saliva, which is why the bites tend to itch and swell at the site. In some individuals the reaction can be more severe, causing the itching and swelling to extend to other parts of the body. Among dogs who are critically allergic to mosquito bites, a life-threatening reaction called anaphylactic shock can occur.

Allergic reactions to mosquito bites are usually mild, but in some cases, the reaction can quickly progress into anaphylactic shock, a potentially fatal condition.

The allergic reaction to mosquito bites can range from mild to critical. 

Mild reaction

• Bumps
• Obsessive licking
• Pawing at the face
• Localized swelling
• Vocalizations

Moderate reaction

• Chewing of feet
• Fever
• Hives
• Lethargy
• Loss of appetite
• Pronounced localized swelling
• Rash on the face or paws
• Swelling of the face 

Critical reaction (anaphylactic shock) 

• Cold limbs
• Coma
• Difficulty breathing
• Elevated heart rate
• Excessive drooling
• Low blood pressure
• Pale gums
• Seizures
• Sudden diarrhea
• Sudden vomiting

If your pet’s symptoms progress from mild to moderate, contact your veterinarian and take your dog to the nearest veterinarian or emergency animal clinic right away. In some cases, symptoms of insect allergy can move from moderate to lethal in less than five minutes. 

Types 

In most cases, the allergic response is the immune system’s reaction to anticoagulant that is in the saliva of the mosquito itself. Mosquitos are also known to transmit other substances to the organism that they bite as well. This means that even an individual without a severe allergy to the saliva can have a serious allergic reaction. This sort of response is usually due to the introduction into the bloodstream of something that the mosquito made contact with shortly before biting the patient, such as pollen, or the blood of an animal that your dog is allergic to.

Allergies in canines are the aggressive response of specialized immune cells in the dog’s body to a protein that it has wrongly identified as a threat. The specialized cells the body uses to protect the body from these threats are called mast cells, and they release histamine when the immune system is stimulated by specific allergens. Histamine has an inflammatory effect on the tissues it comes into contact with, which can result in the itchy and inflamed skin conditions characteristic of most allergic reactions in canines.

As the allergen is injected directly into the body, the allergic reaction to a mosquito bite is usually rather rapid, and the bites can often be identified on sight. The timing of the symptoms combined with the results of a physical evaluation by your veterinarian will usually result in a preliminary diagnosis of allergy. Although there is no blood test to directly detect the antibodies that are present in the mosquito saliva, tests can be done to check for the presence of enterocytes, a specific type of white blood cell that is indicative of an immune response to an allergen. Confirmation of an allergy will generally be followed up with an intradermal skin test to determine which allergen is responsible for the reaction. To complete an intradermal skin test, also known as a patch test, tiny amounts of the suspected antigen are injected under the skin to induce a localized reaction for identification.

If your pet is showing signs of anaphylactic shock, treatment is likely to begin before a definitive diagnosis is received. Epinephrine will be administered upon your arrival to the veterinarian’s office and supportive therapies such as IV fluids and oxygen are likely to be offered as well. In less critical reactions, hydrocortisone or antihistamine shampoos and salves are often applied to relieve the swelling and irritation, but caution should be employed during application as ingestion of hydrocortisone can cause your pet gastric distress. Medications such as corticosteroid injections or oral tablets are usually very efficient in reducing the signs and symptoms of allergy, but they are only recommended when other treatments have failed as they have some serious side effects. 

Injected immunotherapy may be another option for dogs that are allergic to insects like mosquitoes, especially with reactions that are present for at least four to six months of the year and are resistant to antihistamines. After the intradermal test verifies the active allergens that are affecting your pet, an injection is prepared with altered antigens specifically designed for your pet. This personalized formula is injected on a weekly or monthly basis, desensitizing them to the offending allergen or allergens. This method of treatment is time consuming and expensive, however, it has a very high success rate, especially in younger dogs.

As reactions to allergens tend to get more aggressive over time, it may be wise to get a prescription for an epi-pen if your dog has even a moderate response to a mosquito bite. This device has an appropriate dose of epinephrine for your dog. Dogs over 45 pounds are generally prescribed a standard adult EpiPen, dogs between 20-45 pounds will use the EpiPenJr amount and animals smaller than 20 pounds will generally be given a syringe with the right sized dose. Use of an EpiPen should be followed by a trip to the emergency room, even if your dog appears fully recovered. Epinephrine is a short-acting drug, and the allergic reaction may resume without proper medical treatment.