In spite of common belief, a normal dog experiences only minor skin irritation in response to flea bites. There will be very little itching, even in the presence of dozens of fleas. A dog, which has become allergic to fleas on the other hand, has a severe, itch producing reaction to flea bites. This occurs because the dog develops an allergic response to the flea's saliva. In the allergic state, the dog's immune system "overreacts" to foreign substances, in this case proteins in the flea's saliva. This overreaction is manifest as itching. When the dog is bitten, flea saliva is deposited in the skin. Just one bite causes intense itching that will last for 3-4 weeks.
The dog's response to the intense itching is to chew, lick or scratch. This self trauma causes hair loss and can lead to open sores or scabs on the skin, allowing secondary bacterial infection to begin. The areas most commonly involved are the lower back, base of the tail and back and insides of the hind legs. These are the sites most favoured by fleas.
Flea allergy is strongly suspected in itchy, young adult dogs (1-6 years) with the characteristic distribution on the body, especially if there is evidence of fleas and/or flea faeces ("flea dirt"). However, in very sensitive animals where only 1 or 2 fleas may be involved, these may escape notice. Flea allergy tends to occur mostly in late spring, summer and early autumn. Often, flea allergy will have to be differentiated from other allergies, and a therapeutic trial will be necessary to confirm the diagnosis.
To achieve the best results, it is important to understand the flea's life cycle. A female flea can lay up to 50 eggs per day! These eggs drop off the pet into the environment, especially carpets, pet bedding. After hatching they develop through larval stages, then spin a cocoon before hatching as young adults to start the cycle again. You can see why a heavy population can build up very quickly during the warm summer months! It is important to realise that only 5% of the total flea population is found on the pet. The other 95% are in the environment.
Although less rigorous treatment protocols may be adequate to keep flea infestation controlled in non-allergic animals, in the case of flea allergy the aim is to prevent any flea from biting the affected animal during its life.
Total elimination of the flea population within the household is the best way to avoid the symptoms of flea allergy, which involves the following 3 steps:
1. Eliminate the flea population from all dogs and cats in the household.
2. Protect them from continued infestation from adult fleas in the environment.
3. Eliminate from the environment the reservoir of eggs, larvae and pupae.
An integrated approach to flea control using a combination of products is generally required for effective flea control for the flea allergic pet. The most appropriate and cost effective programme must be formulated, aiming at all in-contact pets and the environment. Your veterinarian will recommend the most appropriate programme for you, following careful consideration of the number of in-contact pets in your household, the environment in which they live, climatic conditions, budget restraints, and convenience. The most effective flea control programme is not likely to be the cheapest, but time and money will be saved in the long run by adopting an effective strategy.