SOUTH BEND, Ind. (AP) — Veterinarians are warning that the mosquito swarms that followed Indiana’s recent spate of heavy rains threaten to spread diseases to pets and farm animals.

The blood-sucking insects transmit the heartworm parasite and other illnesses that can sicken cats, dogs, horses and other animals.

South Bend veterinarian Chris Payton says the biggest challenge that animal owners face is that there’s “no magic” spray that keeps mosquitoes at bay.

Payton tells the South Bend Tribune that pets should be tested for heartworms each year and it’s important to catch the parasites before they grow big and costly to treat.

Horses can pick up diseases through mosquito bites, including the West Nile virus and Eastern and Western equine encephalitis.