Virginia Simpson and Chance


by Elizabeth Gigis, DVM, West Chester Veterinary Center

The sun is shining and the temperatures moderate. It’s a great time to take man's best friend out for a day at the park. You put Buddy’s leash on and head down to the local dog park. It’s a great way to spend the afternoon. There is nothing better than watching Buddy making new friends at the dog park. A few days later, however, you notice Buddy seems irritated. He can't sit still! He is biting all off the hair off his back end and scratching like crazy. You inspect closer... little black things are climbing all over him...what in the world? Oh no, Buddy has Fleas!

The foe of all dogs and dog owners and the most common external parasite of dogs is the flea. How do we rid Buddy of this common infestation? First we need to know our enemy.

The most common flea that we find on our pets is the actually the cat flea, Ctenocehpalides felis. Most people think of fleas as a nuisance, however in some cases, fleas can actually be deadly. Fleas cause several diseases, such as tapeworms, flea allergy dermatitis, and even can transmit the bubonic plague! Severe flea infestations in young, old or debilitated animals can lead to life-threatening anemia (low red blood cell count).

There are four stages of the flea life cycle, and it is important to break the life cycle in more than one place. The more stages of the life cycle you can affect, the more effective you will be at getting rid of and preventing flea infestations. One single adult female flea lays up to forty eggs per day. These eggs fall off of the pet and land in the pet’s environment-your carpet. Eggs incubate best at temperatures above 65 degrees and in high humidity (like Ohio in the summertime). Eggs hatch anywhere from two days to two weeks, depending on the environmental conditions. As the eggs hatch, they become larva, resembling little caterpillars, crawling around. The larva feed on everything they find in the carpet-such as digested blood from adult flea feces, dead skin, hair, and feathers. This is the stage that fleas can pick up tapeworm eggs, which can later be transmitted to your pet. The next stage is the pupal stage, where the little flea caterpillar spins itself a cocoon, where it will develop into the adult flea. Fleas in cocoons are very hardy, and can last several months, including over a hard winter, to emerge and hatch in the spring. Pupae are especially protected in carpet, and will remain there, hidden, until stimulated by a nearby pet to emerge and feed. The mature pupae will be stimulated by movement, light, and even carbon dioxide from your nearby pet. Then it will emerge, ready to eat.

A common history may be that you take your dog to a boarding facility and go on vacation for two weeks. You come home, and after a day or so, you find your dog eaten up by fleas. You think, ”That boarding kennel gave my dog fleas!” Actually, what happened was the pupae, stimulated by a returning host, quickly emerged, hungry and ready to feed. This is why pets need constant and continual flea protection, not just spot treatments when adult fleas are seen. It’s for the part of the flea life cycle which lays in wait, hibernating for months, protected until they decide to emerge. The adult flea will emerge, find its host, feed, and then begin to produce eggs 24 hours after feeding. The adult flea will lay eggs continuously until dying. The lifespan of the adult flea is four to six weeks. On average, it takes three weeks from egg to adult flea.

Flea control products are a billion dollar industry! How do you know which product is most effective? First, let me explain one small difference between flea control products and other medications you may get from your veterinary clinic. Many flea control products are classified as pesticides and are regulated by the EPA not the FDA (Food and Drug Administration). Thus, you can buy lots of flea control products over the counter. However, it is important to discuss your choice with your veterinarian, because these chemicals are not all benign. In fact, some can be very toxic to small dogs and especially cats. Some can cause local reactions on the skin surface, and some may not really be that effective at all. As discussed before, it is important to break the life cycle in multiple places. Products that kill adult fleas are called adulticides, and contain pesticides such as imiticloprid, permethrin, and fipronyl. Thus, when newly hatched adult fleas jump on your pet, from the home or another animal, they will be quickly killed before they can produce a lot of eggs. Many developments have also been made in the way of breaking the flea life cycle, and this is done with an IGR, or insect growth regulator. Eggs and pupae are quite resistant against insecticides, so other products such as as pyriproxyfen or methoprene are used to target these stages. Lufenuron is another IGR which sterilizes the adult female flea, not allowing her to produce eggs.

Since three quarters of the flea’s life is actually spent off the host, it’s crucial to treat the home and outdoor environment. This is where the eggs, larvae and pupae can live. A study done by UC noted that vacuuming can rid the home of up to 96% of adult fleas. It is important to also pay close attention to your pets sleeping area. Wash all bedding in hot water at least once per week. Since fleas survive in a warm humid environment, adding a dehumidifier and running the air conditioning should also help eliminate fleas. After vacuuming, you can use sprays, foggers and carpet powders containing insecticides and IGRs that can be used to treat the carpet for flea infestation. There are also several products that can be used outdoors to control flea infestation. It can be nearly impossible to kill all fleas in the environment. The most important point is to keep treating your pet for at least six months with an adulticide and an IGR (flea sterilizer). If some fleas left are able to hatch, they are quickly killed after jumping on your pet and are not allowed to reproduce.