Fleas are tiny, wingless, blood-sucking insects that are an annoyance to people and their pets. They also can carry and transmit serious diseases. Adult fleas are dark brown to black, fairly flat, about 2 to 3 millimeters in length and can be seen with the naked eye. Although they cannot fly, fleas have powerful back legs that give them extraordinary jumping capabilities. They are known for their rapid rate of reproduction. There are many species of fleas. Different species gravitate toward different hosts, especially cats, dogs, rabbits, rodents, horses, birds and humans. However, if fleas are hungry enough, they will feed on almost any available animal. The fleas that affect domestic dogs are Ctenocephalides canis and Ctenocephalides felis. Despite its name, the ordinary cat flea - Ctenocephalides felis – is by far the most common flea species that bothers pet dogs. Ctenocephalides canis is fairly uncommon in the United States.
Causes of Flea Infestation
Dogs become infested with fleas when they live in an area that is conducive to the flea life cycle, and when appropriate flea preventative steps are not taken. Fleas thrive in warm, damp climates. An average temperature in the range of 70 to 85 degrees Fahrenheit, in a moist environment, is optimal for these parasites. From a flea's perspective, the hotter and damper, the better. Accordingly, dogs living in hot, humid areas tend to develop more severe complications from flea infestation than do dogs living in cold, dry climates. Dogs can also get fleas by coming into contact with other animals that have a flea problem.
Fleas only spend a small part of their lives on the skin of a host animal. Adult fleas mate after they eat a large blood meal. Females lay their eggs within 1 to 2 days; they can produce upwards of 2000 eggs during their short 4-month lifespan. Flea eggs fall off of the host shortly after they are laid and incubate wherever they land. The eggs hatch into larvae in about 10 days. Flea larvae can survive for a long time in the environment – reportedly up to 200 days. Fleas tend to like deep pile and shag carpeting, floor cracks, furniture and bedding. They eventually spin a cocoon and enter a pupal stage, which can last anywhere from days to months. This is considered to be a resting phase, during which the pupae do not eat. Once the temperature and humidity are right, the pupae hatch from their cocoons and emerge as immature adults. They have one to two weeks to find a host, or else they will die. Adult fleas can live up to 4 months on a dog, but they cannot survive very long in the environment. Only about 1% of the total flea population, at any given time and in any given area, is comprised of adults. Most fleas are free in the environment in egg, larval or pupal forms.
Prevention of Flea Infestation
Fortunately, there are many things that dog owners can do to keep fleas under control. Some of the most effective ways to manage fleas are to keep a dog's living environment clean and to use veterinarian-recommended flea preventatives. Regular grooming will give owners an opportunity to inspect their dogs' skin and coat for fleas and other external parasites. If open wounds or suspicious "salt-and-pepper" particles are present, whether or not adult fleas are actually seen, a trip to the veterinarian is probably worthwhile. The salt-like particles are flea eggs; the "pepper" particles are flea feces.
Fleas from dogs can and do bite people, which means that flea infestation has zoonotic potential. Fleas have an unparalleled ability to jump great distances and to great heights. Adults will jump onto a host animal and begin feeding as quickly as they can. A single adult flea typically feeds for at least 8 hours a day, ingesting about 15 microliters of blood during that time. Fleas need to feed on blood before they are able to reproduce.
How Fleas Affect Dogs
Fleas are more than just annoying insects. They are the leading cause of itchiness (pruritis), scratching and skin irritation in companion dogs. Fleas cause some degree of irritation simply by crawling around on a dog's skin. Inevitably, once they settle on a host, they quickly begin to dine. Fleas survive by biting into their host's skin and feeding on its blood. Some dogs have fairly mild reactions to flea bites. Others, however – especially young puppies and small-breed dogs – become severely anemic and gravely ill from the blood loss caused by heavy flea infestations.
Symptoms of Flea Infestation
One of the most common problems caused by fleas is a hypersensitivity reaction. In a nutshell, this is a severe allergic reaction to certain substances that are found in flea saliva. Dogs that are hypersensitive to flea saliva can have horrible reactions from only a few flea bites. They become intensely itchy. The most frequently affected areas are the rump, thighs, tail base, belly, flanks and upper arms (especially under the arm pits). Owners of dogs with fleas may notice one or more of the following signs in those or other areas:
Skin abrasions (sores) - often red, raw, weeping and/or bloody
Pus oozing out of skin sores (pyoderma) – caused by secondary bacterial infection
Patchy areas of hair loss (alopecia)
Tapeworm segments on or around the dog's anus and in the stool
Tapeworm larvae on or around the dog's anus and in the stool (look like rice)
A dog's self-mutilation in reaction to flea bites sets the stage for potentially devastating secondary bacterial skin infections, which can be fatal. Many dogs that do not have flea allergies still develop severe flea bite dermatitis as a result of the mechanical skin irritation caused by these biting bugs.
In addition to causing skin damage, fleas can carry and transmit a number of potentially serious diseases. Fleas are intermediate hosts for Dipylidium caninum tapeworms. Dogs that ingest adult fleas during their licking and chewing episodes are at high risk for becoming infected with these tapeworms. Children can also develop tapeworm infections if they get fleas into their mouths through any route.
Fleas act as carriers of other infectious microorganisms, including those that cause plague (the bacteria Yersinia pestis), tularemia (the bacteria Francisella tularenis), typhus (Rickettsia bacteria) and myxomatosis (Leporipoxvirus, which causes severe generalized disease in rabbits).
Dogs at Increased Risk
Dogs living in hot, damp climates in close quarters with other dogs are at increased risk for becoming infested with fleas. Fleas thrive in such environments and, because of their remarkable jumping abilities, they frequently leap from one animal to another.
While prevention is the best cure for fleas, quick treatment of flea-related medical conditions is the next best thing. There are many ways to control flea populations. The affected dog and all other animals in the household should be treated. A flea comb can be used to remove fleas, especially from short-haired dogs and cats. The fleas should be killed immediately; this can be accomplished by putting them into a sealable container with a bit of liquid detergent or rubbing alcohol. Topical on-spot liquids, foams, shampoos, dips, powders, dusts, sprays and collars are available to treat dogs infested with fleas. Some of these products only kill adult fleas, while others kill their larvae and/or prevent their eggs from maturing and hatching. Some flea treatments also control other parasites, such as lice, mites, ticks, roundworms, hookworms, whipworms and/or heartworms. Steroids and antihistamines may be prescribed to help relieve the itchiness and other bothersome symptoms of flea infestation.
One of the most important aspects of flea control is to eliminate the reservoir of fleas that are not on a dog but instead are living and maturing in the house and yard. Thorough mechanical cleaning of all floor surfaces by sweeping, mopping and/or vacuuming is a good place to start. Insecticidal carpet shampoos, sprays, powders and foggers are widely available over-the-counter. Professional exterminators offer a number of services to eliminate fleas and may be especially appropriate in cases of heavy infestation. The yard should be treated as well, including any kennels, runs, pens, dog houses and preferred pet napping spots.
Owners should consult with their pet's veterinarian before using flea-control products, because they can vary widely in safety, method of action and effectiveness. For example, some products should not be used on puppies under a certain age, on pregnant bitches or on specific breeds, depending upon their particular formulations. Some flea control products are toxic if ingested in large amounts, which can happen when a dog licks or chews at its fur after the products are applied. Other flea treatments are not recommended for use in homes with young children.
The outlook for most dogs with fleas is good to very good, if effective flea control is established and maintained. This requires diligence, patience and tenacity on the part of owners.