Allergic Symptoms in Dogs

Dogs suffer from as many allergies as humans, but the pet can't explain its symptoms to the owner. When owners first note their pet's symptoms or behavior changes they should consult a veterinarian. A veterinarian has the diagnostic skills needed to determine if their dog's symptoms represent allergy problems, or more serious illnesses that share symptoms similar to allergies.

  1. Itching Skin

    • Flea allergies--usually because of the flea's saliva--are the most common cause of itching skin that dogs try to relieve by scratching and biting. Allergies to food also cause severe skin itching. A pet may also be allergic to materials or plants in their environment that they only encounter occasionally. If the itching is constant, the problem may be food or fleas. If the pet is flea-free and the itching symptoms are sporadic, the pet may only occasionally come in contact with the allergen. Flea itching is worst on the dog's rump and tail, although it can be everywhere on the dog. Contact allergies with plant pollen especially cause itching around the nose, mouth and eyes. Food allergies also affect the dog's muzzle. Owners and veterinarians must experiment to identify the allergen.

    Hair Loss

    • Hair loss results from the dog's chronic scratching and biting at the itchy red bumps produced by flea bites and food allergies. Bacterial and yeast infections may result from the constant irritation of the skin and also produce hair loss. The rump and the end of the tail tend to show the most hair loss because of flea infestations. Food allergies cause generalized alopecia.

    Skin Eruptions

    • Flea bites and food allergies both cause the dog's skin to break out with hard, red bumps. The pet can develop the red, flaky skin of seborrhea. The irritated skin can develop bacterial and yeast infections that cause more inflammation and red areas on the skin, leading to sores and lesions.

    Hacking Cough

    • Chronic allergic bronchitis causes a harsh, hacking, dry cough. It doesn't cause signs of a cold such as fever. The dog coughs after any exertion. Veterinarians can diagnose it by applying light pressure on the trachea that will trigger the coughing, and by testing bronchial mucous. The symptoms can be sporadic or continuous. Veterinarians are rarely able to identify the responsible allergen, but can treat the symptoms with medications that loosen the mucous and antihistamines to reduce the allergic reaction.

    Eye Problems

    • Food allergies and contact allergies, such as pollen or the leaves of certain plants, particularly affect the dog's eyes and muzzle. The eyelids can become red and swell, a condition known as blepharitis. The eyes may develop conjunctivitis, which is a sticky, white to yellow discharge from the eyes.

    Nausea and Diarrhea

    • Nausea and diarrhea are symptoms of food allergies. The most common problem foods are chicken, eggs, beef, corn, wheat, milk and soy. The veterinarian must first rule out other allergies and diseases. If the vet suspects food allergies, then she recommends feeding a test diet to the dog for 90 days. If the allergy symptoms improve or disappear during the test, the pet owner can reintroduce the suspected foods one at a time. The problem food can make symptoms reappear in one hour or take up to 14 days. Dogs can develop food allergies as they age.