The first thing you will notice is hair loss along your dog’s neck, spine, and thighs. The skin is speckled with crusts and feels hot. Then there is scratching: automatic, reachable with the back foot, cannot be suppressed. You may or may not see live fleas or very little flea debris (stains from digested blood).
Often a customer says to me, “But my other cat / dog is fine.”
But that’s it – not all pets are allergic to fleas. But for those who are, the suffering can be extreme. Itching causes significant stress; as Dante wrote in his 14th century epic poem inferno: “Since everyone quickly pressed the bite / the nails on themselves, for the great anger / the itching that no other support had.”
Flea allergy dermatitis (FAD) occurs when a dog’s immune system overreacts to flea saliva. The severity of the itching does not necessarily correlate with the number of flea bites the dog has to deal with. Sometimes it only takes a few to create a fair amount of scratches. Many dogs also have secondary bacterial and yeast infections, as well as environmental allergies, which make itching worse.