The first thing you notice is hair loss along your dog’s neck, spine and thighs. The skin is flecked with scabs and hot to the touch. Then there’s the scratching: automatic, back-foot-reaching, irrepressible. You may—or may not— see live fleas, or only scant flea dirt (specks of digested blood).
Often, a client will say to me, “But my other cat/dog is just fine.”
That’s just it, though—not all pets are allergic to fleas. But for the ones who are, the suffering can be extreme. Itching causes a distinct distress; as Dante wrote in his 14th-century epic poem Inferno: “As every one was plying fast the bite/Of nails upon himself, for the great rage/Of itching which no other succor had.”
Flea allergy dermatitis (FAD) arises when a dog’s immune system overreacts to flea saliva. The severity of the itching doesn’t necessarily correlate to the number of flea bites the dog’s dealing with; sometimes, it only takes a few to generate a whole lot of scratching. Many dogs will also have secondary bacterial and yeast infections as well as environmental allergies, all of which aggravate the itch.
William Oldenhoff, DVM, DACVD, is a dermatologist at LeadER Animal Specialty Hospital in Cooper City, Fla. He prefers to attack FAD from several different directions. The first step is the year-round use of a flea preventive, which takes a while to resolve the infestation because the flea life cycle ranges from one to two months, depending on environmental conditions, and pupa can survive for up to a year before becoming adults.
Oldenhoff also advocates thorough house cleaning. “Vacuum all surfaces, paying particular attention to the areas just adjacent to walls and corners, and under furniture. Be sure to clean the furniture as well, and launder any bedding the dog sleeps on.” He does not recommend having the house itself sprayed or otherwise treated, since flea preventives and meticulous environmental cleaning are usually adequate.
Oldenhoff’s third treatment tier includes a systemic such as oclacitinib or steroids to relieve the itching. However, he cautions, the fact that the dog stops his mad scratching doesn’t mean the fleas are gone. “When these therapies are prescribed, the owner must be made aware that the pet will be feeling much more comfortable, but the flea infestation is still present, and thus flea control must still continue.”
Other FAD treatment considerations include medications for secondary bacterial and yeast infections, and a dewormer for tapeworms. Fleas harbor Dipylidium caninum larvae, aka the flea tapeworm. If an infected flea is ingested—for example, as the dog grooms himself—the larvae develop into adult tapeworms in the dog’s intestines. According to the Center for Disease Control, the risk of a Dipylidium infection is rare in humans, and the infection rarely causes harm to either humans or animals; treatment with oral praziquantel is simple and effective.
If flea control depends on flea products, and these have been used for many years, do fleas develop resistance? Hypothetically, they could, or the problem may be one of perception. As Michael W. Dryden, DVM, PhD, notes in Clinician’s Brief, “The continued emergence of fleas in a home and the presence of fleas on pets for several weeks after treatment [are] actually quite normal. In fact, the problem often worsens before it improves, depending on the number of eggs deposited and survivability of larvae.”