Summertime Blues: Flea and Tick Season

Warm weather brings with it the increased likelihood that pets and pet owners will have to deal with fleas, ticks, and the problems that they can cause. The milder temperatures and increased humidity in the summer provide ideal conditions for survival and increased reproduction rates for both of these problem pests. Also, pet owners and their pets are more likely to encounter fleas and ticks during warm-weather strolls or outdoor events. Fortunately, there are many safe and effective flea and tick preventive products that can help us control these parasites. Here, we discuss the importance of fleas and ticks and review control strategies.

FLEAS

Fleas are insects and are related to ants, beetles, and even butterflies. In fact, their developmental cycle is most like that of butterflies and moths. Adult fleas feed on our pets’ blood, then mate and produce eggs that fall from the pets’ haircoat into the environment. Maggotlike larvae emerge from eggs and shed their outer “skin” twice. Larvae feed on blood particles excreted by adult fleas (flea feces). These particles are dislodged from a pet’s haircoat and fall into the environment during scratching and movement. Eventually, the last larval stage develops into an adult flea inside a resting cocoon (yes, very similar to a butterfly or moth). When it is stimulated by movement, pressure, heat, or carbon dioxide provided by our pets, the adult flea emerges, jumps on the pet, and begins to feed. All of this takes place in as little as two weeks. However, if conditions are not just right, the life cycle can be prolonged for weeks or months.

It is important to remember that adult fleas on the pet comprise just 5% of the total number of fleas. Most fleas (95%) are developing in the environment or are waiting as adults in cocoons. Because of this, complete flea control may take several months from the time that pets are placed on flea control products.

Fleas are important because their bites cause irritation and can induce skin allergies in pets. Fleas can also transmit other parasites (such as tapeworms) and diseases to pets and pet owners. Cat scratch disease is a disease of humans that is caused by a bacteria present in flea feces. The disease is transmitted between cats by fleas. Cats accumulate the bacteria under their claws when they scratch themselves. People are infected when they are scratched by cats whose claws are contaminated with the agent. One way to prevent cat scratch disease is to prevent fleas from transmitting the agent from cat to cat. Successful flea control can help prevent this and other flea-transmitted diseases as well as the irritation caused by these parasites.

TICKS

Ticks belong to a different group of parasites (arachnids) and are related to mites, spiders, and scorpions. The most common ticks in the United States are the brown dog tick, the American dog tick, the Rocky Mountain wood tick, the deer tick, and the Lone Star tick.

The developmental cycle of ticks includes four stages: egg, larva, nymph, and adult. Adult ticks have eight legs, a leathery dorsal covering called a scutum, and imposing mouthparts used for attachment. Adult female ticks have expandable bodies and feed for long periods at one attachment site until they are engorged (full of blood). Adult male ticks have less capability to expand, feed for short periods, and tend to move from site to site.

After engorgement and mating, adult female ticks drop from the host, seek a sheltered site, and lay hundreds to thousands of eggs. Eggs develop in these sheltered sites and release six-legged larvae, which are often referred to as “seed” ticks because of their small size and their role in initiating the tick life cycle. The larvae usually feed on mice or lizards. After feeding to engorgement, larvae drop from the host and molt to the eight-legged nymph. Nymphs resemble adult ticks but are smaller and sexually immature. Nymphs often feed on intermediate-sized mammals such as rabbits, squirrels, opossums, and raccoons, but they will also feed on larger animals, including humans. After engorging on blood, the nymph drops from the host and molts to the adult tick. Like the previous life stages, adults locate and feed on a third host. Hosts for adult ticks are usually larger mammals such as dogs, cats, cattle, horses, deer, and humans.

Ticks that infest dogs and cats in the United States are referred to as threehost ticks because each of the motile, or active, stages (larva, nymph, and adult) attaches to and acquires its blood meal from a different host. For most of the tick species, each host is a different animal. However, larvae, nymphs, and adults of the brown dog tick will all feed on dogs. For this reason, the brown dog tick can become a serious pest in kennels and homes with many pets.

When asked which bug is responsible for transmitting the most diseases in North America, many people would probably answer “mosquitoes.” As it turns out, ticks are actually more important vectors of disease in North America than mosquitoes. Ticks are very good at transmitting diseases for several reasons: They feed for long periods of time, they take in large amounts of blood, they can feed on many different animals, and they are usually distributed over wide areas of the country.

Diseases transmitted by ticks in the United States include Lyme disease, Rocky Mountain spotted fever, anaplasmosis, babesiosis, cytauxzoonosis, ehrlichiosis, hepatozoonosis, and tularemia. Certain of these diseases can occur in dogs or cats and humans. In fact, Lyme disease is the number one vector-borne disease of humans in the United States. (A vector-borne disease is one that is transmitted from one host to another by an insect or arachnid.)

CONTROLLING FLEAS AND TICKS

Flea and tick control is best achieved by placing pets on an available flea or tick preventive product. There are numerous product choices out there, and your veterinarian can determine which is the best option for your pet.

Flea and tick products are available in many forms, including topical spotons, oral tablets or liquids, and injectables. Many products are what we call residual adulticides because they kill adult fleas or ticks (they also kill tick larvae and nymphs) and do so for at least one month. Most of these products work by paralyzing the flea’s or tick’s nervous system, resulting in rapid death.

Some products contain ingredients called insect growth regulators (IGRs) that prevent flea growth and development. A few products contain both adulticides and IGRs. Many of the new flea control products contain new chemical agents that have not been used previously against fleas. It is important to have a choice of different chemical ingredients in these products in case fleas develop resistance to one of the chemicals.

Tick control agents should prevent ticks from feeding or limit their feeding to as little time as possible. Not only will this interrupt the life cycle because female ticks must acquire blood to produce and lay eggs, but it will also decrease the probability of disease transmission. Many products on the market target the nerves and muscles that control the tick’s mouthparts, making it difficult for affected ticks to attach and feed on pets. All the products eventually affect the tick’s general nervous system, resulting in paralysis and death.

Choosing an appropriate flea and tick control product depends on several factors, including numbers and types of pets in the household, their indoor/ outdoor status, the region of the country in which you reside, whether fleas and/or ticks are the problem, the capability of the pet owner to administer products safely and accurately, and other existing pet health conditions.

Many professional veterinary organizations such as the Companion Animal Parasite Council (CAPC) recommend that all pets be on flea and tick control products year-round. The CAPC consumer website, www.petsandparasites.org, contains information on fleas, ticks, and vector-borne disease, as well as information and commentaries on many other parasites. The CAPC year-round recommendation is endorsed by the American Animal Hospital Association and the American Association of Feline Practitioners.

As mentioned earlier, successful flea and tick control can be a challenge. Your veterinarian is your best source of information; he or she can help you decide which flea and tick product is best for your dog or cat. This summer, knowing that your pet is protected against these pests can help you enjoy your time together that much more.

ADDITIONAL CONTROL MEASURES FOR FLEAS AND TICKS

• Vacuum indoor carpets and solid surfaces using a vacuum with a rotating bar.
• Vacuum furniture using appropriate attachments.
• Wash bed linens, pet bedding, and rugs frequented by pets.
• Mow lawns regularly.
• Clear brush, leaves, and tall grass from around houses, gardens, and walls at property margins.
• Stack wood off the ground in a dry location away from the house.
• Clear gardens, including remains of perennial plants after the growing season.
• Consult with your veterinarian and a licensed pest control specialist to assess the need to use pesticides in selected areas in and around your home.