Parasites have to make a living too, you know. Virtually all of us would prefer, however, that they never set foot on our pets. Parasites deal in misery: itching, scabbing, scaly skin, weight loss, weakness, liquid stools. They’re the embezzlers of the animal world—unobtrusive, but oh, so greedy.

In developed nations with good sanitation and reasonable health care, parasitism is no longer much of a risk to humans. Accepting a non-human animal into our homes, however, opens the door to individuals who eat crickets or crayfish, lick their paws after dancing through the grass, snuffle vigorously under the tails of others, and occasionally (only occasionally!) nibble (lightly, I say!) at carrion and feces. That same individual is licking your fingers, rubbing his body against your furniture, and huddling between your knees on chilly nights. It’s in everyone’s best interest to protect this individual from himself and his own casually considered actions.

Cat owners, did I lose you? Don’t wander off! Intestinal worms can be ferried across your threshold by crickets, cockroaches, houseflies, rodents, and the potting soil used in your houseplants. Does your cat ever scratch and munch in the houseplants? Did you know that 25-30% of cats diagnosed with heartworms spend all their time indoors?

Because it poses the greatest danger to your pet, the heartworm resides at the hub of our parasite intervention efforts. Diethylcarbamazine (DEC) was the first medication capable of preventing heartworm infections, and it needed to be given every single day of every summer. Administration of DEC had to be meticulous: just two missed doses left an unacceptable gap in protection. In 1987, a monthly pill was unveiled, and it completely revolutionized heartworm control by safely condensing the entire year’s medicine into twelve tablets. A further advancement was the incorporation of ingredients to curtail commonplace pests like hookworm, roundworm, mange mites or fleas, and that’s how we got the products we have today. Different brand names boast different kill profiles, but the goal is always the same—to provide continuous protection against the widest possible array of parasites. It’s ridiculously easy and effective compared with the days of DEC, and very safe, especially when compared with early parasite therapies calling for substances such as cigar stubs, dry cleaning fluid, and burned motor oil.

Heartworm preventative is now given year-round. The heartworm itself is limited somewhat by outdoor temperatures, but most of those secondary parasites are conducting business as usual, regardless of the weather. Did you know that some of them can also infect humans?

It’s so easy and inexpensive to protect your pets, your children, and yourself from parasites these days. You probably can’t stop your cat from snatching houseflies or your dog from eating grass, but you can stop putting out the welcome mat for worms and bloodsucking bugs. It’s simple and painless, and it’s only once a month. Parasites do have to make a living somehow, but they don’t have to do it in your home.

 Dr M.S. Regan