by Michael Dryden, DVM, MS, PhD – Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas
Fleas and ticks are more than mere nuisances. They cause distress in dogs and cats and, more important, they cause disease. On-again, off-again preventive programs are not the optimal way to safeguard the health of pets and their families.
By the time a pet owner notices fleas on a pet, the fleas have injected salivary proteins, transmitted infectious agents and begun laying eggs. Ticks can transmit disease agents to a dog or cat before the pests are found and removed.
Clearly, reactive treatments are insufficient to prevent disease in pets and their owners. That’s why I support the Companion Animal Parasite Council (CAPC) guidelines, which call for year-round, lifelong prevention of common external parasites, including fleas and ticks. The guidelines recommend using parasite control methods that consider the lifestyle and health of the pet, managing the pet’s environment, and working closely with owners to prevent infestation and protect the health of the entire family.
Stopping flea reinfestation key to preventing disease
Most residual insecticides, including selamectin, fipronil, imidacloprid and nitenpyram, effectively eliminate existing fleas from dogs and cats within 4 to 24 hours after application. While this helps relieve pet discomfort, reinfestation is common.
Administering a residual insecticide will kill many newly acquired fleas within 24 hours. However, in that brief interim period, fleas may transfer disease agents, trigger flea allergy or produce enough eggs to reestablish infestation. Repeated applications often are necessary to bring this problem under control, and long-term control methods should be used to prevent reinfestation.
Topical or oral IGRs(insect growth regulators) such as lufenuron, methoprene, selamectin, or pyriproxyfen kill flea embryos or larvae within the egg. These products turn the treated dog or cat into a “flea vacuum.” As it moves through an infested environment, the pet acquires emerging fleas, which are killed rapidly by topical or systemic insecticides and their eggs are rendered nonviable by the ovicidal action of the compounds. Once all life stages have developed and emerged, the flea problem is over. This system works well to eliminate an infestation, but may require four to eight weeks or longer to eradicate all fleas. During this interval, both pets and owners can suffer. Avoiding initial infestation altogether by placing pets on life-long prevention programs is the best option for pets and their owners.
Trickier tick control
Tick control is vital, since these bloodsucking parasites can transmit disease to pets and owners. Nearly a dozen tick species are encountered by U.S. dogs and cats. Most are potential disease carriers, transferring diseases as prevalent and concerning as Rocky Mountain spotted fever (Rickettsia rickettsii) and Lyme disease (caused by Borrelia burgdorferi).
Several studies have evaluated the efficacy of acaracides against ticks that infest dogs, but only a few have considered how well acaracides prevent tick-transmitted diseases. In one study, Lyme disease infection was halted by amitraz-impregnated collars, fipronil spray and a permethrin- imidacloprid spot-on treatment. Another study found fipronil spot-on significantly reduced transmission of E. canis by R. sanguineus.
While these studies provide valuable data, no product can completely prevent all tick-transmitted diseases, and successful control depends on pet owner compliance. Owners may miss a few ticks on their pets for a day or two—enough time for disease agents to be transmitted from tick to pet. While not a perfect solution, disease transmission can be reduced by keeping pets on effective tick control programs.
Seasonal prevention may be inadequate
While seasonal flea and tick control seems appropriate in many regions of the U.S., sporadic treatment makes it difficult to prevent initial infestations. Due to changing climatic conditions, flea and tick “seasonality” also is changing. Experience over the past 10 years shows every year has the potential to differ from the previous year. Determining start and stop dates for seasonally timed applications may be impossible, and geographic differences affect flea and tick prevalence and seasonality.
In addition, many pets receive broadspectrum macrolide heartworm preventives. Heartworm and intestinal nematode transmission seasons occur at different times than flea and tick seasons. If veterinarians find it difficult to reconcile and respond to these shifting seasons, how can we expect clients to manage pest control timing? Year-round prevention is simply the most practical and medically sound approach.
The best prevention for flea- and tickborne disease is clear: year-round prevention of flea and tick infestation. Simplify your client’s lives and enhance the health of your patients and their owners with comprehensive 12-month parasite control.
Editor’s note: For more comprehensive information about prevening transmission and treatment of parasites, visit http://www.capcvet.org<./p>