Spring is here for many of us; the season of renewal, of warmer weather, longer days, flowering trees
and shrubs, and bright-colored blooms . . . and fleas.
By late spring, fleas begin to emerge from their pupae as adults and migrate
to the nearest dog or cat for blood meals. An adult flea mates shortly after
emergence and begins laying eggs within 36 hours. In her brief 50-day lifespan,
a single female flea can lay more than 2000 eggs.
Signs of infestation
Fleas are masters of their universe. They can hide in a forest of pet hairs,
especially on long-coated or double-coated dogs, and can zig-zag among and
between hair shafts faster than an Olympic skier on a slalom course. And then
there's the leap. Now you see a black speck with legs, and now you don't.
So, don't depend on seeing the flea to know if he's there. Instead, look for
clues.
If Fido scratches, he may have been bitten, but he may also have dry skin, an
allergy, or mange mites. If he bites at his rear end especially around his tail
or the inside or outside of his thighs, fleas are a possibility. If you find
tiny black particles that turn red when dropped on a damp paper towel, voila! —
flea feces, the damning evidence.
While Fido may be slightly bothered by a flea or two or may play host to a
dozen or more without serious consequences, Rocky may be the unlucky recipient
of a tapeworm infestation courtesy of mama flea and Sassy may be allergic to
flea saliva and develop mild to severe skin reactions to even a single bite. The
tapeworm or the skin bumps may be the only signs that the fleas are present.
Flea bite dermatitis
When flea bites dog, proteins (antigens) in the insect's saliva can cause an
immune system reaction — the release of immunoglobulin that in turn causes
itching. Depending on the type of cell involved (mast cells, basophils, or
T-lymphocytes in the blood) and the type of chemicals released, the irritation
can begin immediately, in five-to-six hours or in 24-48 hours or a combination
of the three — all from a single bite.
Small red raised bumps on the base of the tail and along the outside of the
back legs, self-induced scratches, and thickened skin on the base of the tail
are all signs of chronic flea allergy. The diagnosis can be confirmed with an
intradermal skin allergy test.
Writing in the AKC Gazette, veterinary dermatologist Dr. John Gordon
describes the intradermal test: “With intradermal (skin) allergy tests, a small
amount of a specific concentration of flea antigen is injected into the surface
layers of the skin. The flea antigen binds to immunoglobulin or is absorbed by
T-lymphocytes to create an immediate, late phase, or delayed reaction.
Unfortunately, late phase and delayed skin test reactions are often considered
negative skin tests because the reaction is not documented. Careful observation
will help avoid this problem.”
Gordon described two other allergy tests that rely on drawing blood from the
dog, but said that they are not as reliable as the intradermal test.
Treatment
Dog owners have access to a plethora of flea control products from herbs and
electronics to biological controls. Powerful chemicals such as Dursban and
diazinon and systemic insecticides such as the ingredients in Proban, Prospot,
and Spotton seem to be on the way out. The systemic insecticides can build to
toxic levels in the dog if not used extremely carefully. Some products repel
fleas, some kill adult fleas, some kill larva or eggs, and some prevent fleas
from growing and reproducing.
Garlic and brewer's yeast are popular flea repellents with the natural crowd,
but there are no tests that indicate these diet supplements are effective. Many
dog owners believe they work, however.
Electronic flea traps are sometimes used to attract and kill the pests before
they attack the dog, but they do nothing about fleas in the yard or flea eggs or
larvae in the house.
Flea collars have mixed results depending on the chemical involved, the size
of the dog, and the density of the dog's coat.
The new generation of controls includes natural or genetically engineered
pyrethrum, a daisy; flea-specific growth inhibitors (products containing
fenoxycarb and methoprene); an environmental control that desiccates fleas and
larvae; a once-a-month pill (Program) that prevents the formation of chitin, the
flea's external body covering; and new surface products applied to the dog's
skin or coat (Advantage and Frontline). Unlike the toxic insecticides in
products such as Spotton, Proban, and Prospot, the ingredients in Frontline and
Advantage are not absorbed into the bloodstream and are toxic only to fleas, not
to dogs or their owners. Program, Frontline, and Advantage are available only
through veterinarians; all other flea controls can be purchased over-the-counter
in pet supply stores or catalogs.
The type of control depends on the extent of the dog's problem and the
preferences of the dog's owner. The pill or topical application take less
effort, but they should not be used alone in a heavy infestation because they do
not treat the environment. The pill works when flea bites dog, so may not be
suitable for an allergic dog. The topical solutions kill adult fleas and have
some residual action as long as they remain on the pet's hair — even hair that
has been shed on carpets and furniture.
Pyrethrums kill adult fleas but are short-lived. Permethrins, the genetically
altered form pyrethrum, lasts for 10 days or so. Pyrethrum and permethrin are
often found in shampoos and in pet and premise sprays containing growth
inhibitors.
With mild flea infestations, an occasional bath with a permethrin shampoo or
a Program prescription may do the trick, especially when combined with a premise
spray that contains a growth inhibitor or with application of sodium polyborate,
an insecticide that kills fleas by lethal constipation and desiccation. More
serious infestations may call for the big guns, especially if the dog is
allergic. But whatever combination platter of flea treatments you choose, make
sure you have something on hand for the hot, humid days of summer when fleas can
invade in hordes.
