Fleas are not only a source of irritation and frustration, but they also pose a serious health threat to animals. These tiny external parasites can carry a variety of diseases, including bubonic plague, and severe infestations may cause deadly levels of blood loss in very small or young pets, according to national animal welfare organizations. Owners must therefore employ every preventative measure to keep these creatures off of their beloved pets, including the use of topical or oral medications.
The first line of defense is prevention. Prevention can be as simple as removing fleas and their eggs from your household by cleaning, vacuuming, and applying pet-safe pesticides to the yard. Keeping your grass mowed and removing excess sources of shade can rob fleas of their preferred environmental conditions, discouraging them from breeding in the yard. But no matter how scrupulously you keep your indoor and outdoor environments under control, at some point your pet is likely to need some form of flea treatment. These treatments may take topical ("spot-on") or oral forms.
Topical or "spot-on" flea treatments are readily accessible to pet owners. These products can be highly effective at eliminating flea infestations or preventing new ones from occurring. Veterinary organizations point out, however, that while approved flea preventatives are generally considered safe, owners must follow the instructions on the label with great care to prevent a possible toxic or otherwise adverse reaction to the chemicals in the product. Animal welfare organizations also warn owners never to give cat flea treatments to their dogs or vice versa, because the results could prove fatal.
Oral flea medications also have their pros and cons. In addition to topical treatments widely available, veterinary clinics also prescribe oral products such as Comfortis. Typically, regular monthly doses of such drugs aim to kill fleas before they have a chance to lay eggs, stopping infestations before they start. You may find that the oral delivery method creates less of a mess than the topical route, while also eliminating concerns over skin reactions to the active ingredients. But oral medications may also cost more than topical treatments, and prescriptions will need to be refilled regularly to maintain constant protection.
AVMA, “Flea and Tick Treatments: EPA’s Investigation of Spot-On.”
Comfortis, “Controlling Fleas in Your Home.”
Cruz, Bernadine, DVM; Mesenhowski, Shannon, DVM, “Save Use of Flea and Tick Preventative Products.” AVMA, Dec 2012.