Urticaria (Hives) & Angioedema (Swelling of the Face)
Holly Frisby, DVM
Veterinary Services Department, Drs. Foster & Smith, Inc.
Urticaria and angioedema are hypersensitivity (or allergic) reactions to drugs, chemicals, something eaten, or even sunlight.
What are the symptoms of urticaria and angioedema?
In urticaria, small bumps occur within the skin. Often, the hair will stand up over these swellings. Sometimes, they itch. In angioedema, we see swelling of the face, especially the muzzle and around the eyes. Sometimes, the swelling is so severe, the animal cannot open its eyes. Angioedema often results in itching. Angioedema and urticaria generally develop within 20 minutes of being exposed to the allergen (substance to which the animal is allergic).
In general, both urticaria and angioedema are not life-threatening and will go away by themselves. Rarely, the swelling in angioedema can affect the throat and make breathing difficult.
How are urticaria and angioedema treated?
Antihistamines are generally the best treatment for angioedema and urticaria. If severe, steroids are sometimes given. If respiration is affected, epinephrine is administered.
Can urticaria and angioedema be prevented?
In general, there is no way to predict which animals may develop urticaria or angioedema as a result of exposure to a certain substance. If a pet has already had a reaction, such as anaphylaxis, angioedema, or hives, to a substance, the substance should be avoided. If your dog has ever had a reaction to a vaccine or medication, be sure your veterinarian knows and the information is placed in your pet's medical record.
If your dog has ever had a reaction to a vaccine, subsequent vaccinations should be given by your veterinarian. Your veterinarian will probably administer an antihistamine prior to vaccination and have you remain in the office for 20-30 minutes after the vaccination, so you are right there if your pet has a reaction. In some cases, certain vaccines may be excluded from your dog's vaccination regimen, or a different type of vaccine will be used.
Many vaccines contain antibiotics as preservatives. If your dog is allergic to an antibiotic, be sure to check all vaccines for the presence of that antibiotic before use.
If your pet has developed urticaria or angioedema from an insect bite, you may want to discuss various options with your veterinarian. Your veterinarian may give you a prescription for an 'epi-pen.' An 'epi-pen' is a special syringe and needle filled with a single dose of epinephrine. If your pet has an anaphylactic reaction or severe angioedema, inject the epinephrine using the 'epi-pen' and seek emergency veterinary assistance immediately. Be sure to take the 'epi-pen' with you on any trips or hikes.
