Topical Insecticides for flea control in dogs

A variety of insecticide products are available to control fleas, but there are differences in safety and effectiveness. Be sure to read the label to make sure the product is specifically intended to control fleas on dogs. Better yet, consult your veterinarian and use the products he or she recommends. Do not use flea products made for dogs on cats or rabbits!

Flea shampoos kill only when they are on the pet. Once rinsed off, they have no residual effect. They are best used for mild to moderate flea infestations when the environment has also been thoroughly treated. In general, pyrethrin-based shampoos are safest, especially on puppies.

Powders and dusts have more residual killing activity, but must be worked thoroughly through the hair coat down to the skin. They tend to leave the coat dry and gritty. Dusting must be repeated two to three times a week, or as recommended by the manufacturer. Dogs who lick or chew on themselves may swallow toxic doses of these chemicals.

Sprays, foams, and dips have the most effective killing action and are the best choices for severe flea infestations and for dogs with flea allergy dermatitis if you are not using a topical preventive such as Advantage or Frontline. Sprays and foams work best on dogs with short coats. Sprays come in pressurized cans and trigger-activated bottles. The hiss of the pressurized can may frighten some dogs, in which case the foam is preferable. Most sprays have a residual killing action that lasts up to 14 days.

Water-based sprays are preferable to alcohol-based sprays, which are flammable and can dry the coat. When using a spray, begin near the back of the dog’s head and work toward the tail. This prevents fleas on the body from escaping the treatment by moving up onto the face.

Sprays and foams should not be used on puppies under 2 months of age, unless the manufacturer’s label says it is safe to do so. Always use these chemicals exactly as directed, because some can be toxic if the dog licks or chews them off the hair.

Insecticide flea dips applied to the coat and allowed to dry are extremely effective in getting rid of fleas. Dips penetrate the hair coat and have the most immediate killing action and the longest residual activity. They also have the greatest potential for toxicity. Before using a dip, read the instructions care- fully. Use according to the manufacturer’s recommendations. If your dog shows signs of toxicity, bathe or rinse her right away. Excess drooling, weakness, or instability in walking are all signs of mild toxicity. For information on how to use a flea dip, see Insecticide Dips.

Flea collars aid in flea control but do not eradicate all fleas. Most collars contain dichlorvos, which turns onto a vapor that surrounds the dog. If the dog sleeps outdoors, the collar will not be as effective. Flea collars lose their potency over time and must be changed every two months, or as recommended by the manufacturer. Dog flea collars should never be used on cats.

Dogs can become sensitive to the chemicals in flea collars and develop contact dermatitis. This can be prevented to some extent by airing the collar for 24 hours when you first take it out of the package and applying it loosely. The collar should fit so that you can get at least two fingers between it and the dog’s neck.

Using a dichlorvos flea collar along with a dichlorvos-containing dewormer could result in the dog absorbing a toxic concentration of dichlorvos. Remove the collar one week before deworming and replace it one week after deworming. Also, do not allow the dog to eat or chew on her collar, as it can be toxic. Initial signs of toxicity may include excess drooling, ataxic gait, and diarrhea.