Stan Wood, DVM, Diplomate ABVP

Specialist in Canine & Feline Practice

Flea Allergy in Dogs

One of the most common conditions affecting dogs is allergy. In the allergic state, the dog's immune system "overreacts" to foreign substances (allergens or antigens) to which it is exposed. These overreactions are manifested in three ways. The most common is itching of the skin, either localized (one area) or generalized (all over the dog). Another manifestation involves the respiratory system and may result in coughing, sneezing, and/or wheezing. Sometimes, there may be an associated nasal or ocular (eye) discharge. The third manifestation involves the digestive system, resulting in vomiting or diarrhea. The specific response that occurs is related to the type of allergy present.

Types of Allergy

There are five known types of allergies in the dog: contact, flea, food, bacterial, and inhalant. Each of these has some common expressions in dogs, and each has some unique features.

In spite of common belief, a normal dog experiences only minor skin irritation in response to flea bites. Even in the presence of dozens of fleas, there will be very little itching. On the other hand, the flea allergic dog has a severe, itch-producing reaction to flea bites. This occurs because the dog develops an allergic response to the flea's saliva. When the dog is bitten, flea saliva is deposited in the skin. Just one bite causes intense itching.

Clinical Signs

The dog’s response to the intense itching is to chew, lick, or scratch. This causes hair loss and can lead to open sores or scabs on the skin, allowing a secondary bacterial infection to begin. The area most commonly involved is over the rump (just in front of the tail). This is probably because fleas find this part of the dog more desirable. Many flea-allergic dogs also chew or lick the hair off of their legs.

Treatment

The most important treatment for flea allergy is to get the dog away from all fleas. Therefore, strict flea control is the backbone of successful treatment. There are many products available for flea control, and many work in entirely different manners. In some cases, multiple products may be needed. Some are used on the dog and some in the dog’s environment. Unfortunately, complete flea control is not always possible for dogs that live outdoors in warm and humid climates, where a new population of fleas can hatch out every 14-21 days.

Some dogs can be desensitized to the adverse effects of fleabites. Flea saliva extract (flea antigen) is injected into the dog in tiny amounts over a prolonged period of time. This is an attempt to reprogram the dog’s immune system so it no longer over-reacts to fleabites. If successful, itching no long occurs or is less intense when the dog is bitten. However, this approach is only successful about 50-75% of the time.

When strict flea control is not possible, corticosteroids (or "cortisone" or "steroids") can be used to block the allergic reaction and give relief. This is often a necessary part of dealing flea allergy. Some dogs respond best to long-acting injections and other to oral medication. Dogs are more resistant to the side effects of steroids than humans, but significant side effects can occur. For this reason, the goal is to administer the smallest amount of steroid needed to keep the dog comfortable.

Some dogs develop a secondary bacterial infection in the skin. When this occurs, appropriate antibiotics must be used.

INSTRUCTIONS: Those instructions that are specific for your dog have been checked:

___ 1) An injection of steroids was given. Relief should be apparent within 12-24 hours. If not, please call. Your dog should feel better and itch less for about one month. It is important that you immediately institute appropriate measures of strict flea control.

If an increase in water consumption or urination occurs, please report this to us for future reference. These side effects are common with steroid administration and will go away in a few days without treatment. They may be avoided in the future by giving a lower dose. Return for further evaluation when the first signs of itching recur.

___ 2) Begin oral steroids when the first signs of itching return. Give ____ tablets every other morning. Adjust the dosage upward or downward to the lowest effective dose, with a maximum dose of __________ permitted. Stop giving the medication every 4-6 months to see if there are times of the year when therapy is not needed. Report any increase in water consumption to us at once.

___ 3) We have dispensed oral steroid tablets. Prednisone is most commonly used. The specific drug being dispensed for your dog is labeled on the bottle. Give ____ of the ____ mg tablets every other day for 3 doses (6 days), then ____ tablets every other day for 3 more doses (6 more days). Continue this downward progression (___________________________) until the first signs of itching recur. At that time, go back to the next higher level and report that level to us (so we can be sure it is a safe level).

Stop giving the tablets every 4-6 months to see if there are periods of the year when they are not necessary. When itching returns, begin immediately at the maintenance dose. If that does not stop the itching, increase the dosage slightly (to a maximum of ___ tablets) for a few doses, then return to the lower dose. Report any increase in water consumption to us at once. (This may occur at the initial dose but should stop on the maintenance dose.)

___ 4) Flea control is very important and should include treating the dog and its environment. The following products are recommended for your situation:

_________________________________________________________________

Bear in mind that flea allergy often accompanies other types of allergy, especially inhalant allergy. If your dog itches when fleas have been eliminated, notify us of that so that we can modify the treatment approach.

___ 5) Your dog has a bacterial skin infection secondary to its flea allergy. The following are recommended:

___a) Antibiotics are to be used for the next _____ days. If the infection is not gone by the time the medication is completed, call for a refill or for a change in medication.

___b) The medicated shampoo,_____________________, is to be used every _____ days. Allow the shampoo to stay in the haircoat for a few minutes before thoroughly rinsing the dog.

___c) The topical medication,_____________________, is to be used ______ times daily for __________ days.