Heartworm disease in cats, dogs and ferrets is fatal if untreated, but it is also preventable. And prevention is much easier and safer than treatment — if you know the facts.

Many dogs are on heartworm prevention medication, but owners of cats and ferrets may not know their pets are at risk too. And because heartworms are usually transmitted by mosquitoes, pet owners may be tempted to avoid preventative medication for an indoor pet or stop treatment when mosquito season is over. But mosquitoes can get indoors and you can’t be certain of exactly when their life cycle begins and ends, so year-round heartworm prevention medication is the safest treatment.

One more thing: As worthwhile as preventative medication is, no medication is 100 percent effective. And because heartworm disease is so devastating, even pets on year-round medication should be checked annually for infection.