Heartworm disease is on the rise in Colorado and now Veterinarians are changing the recommendations for treating dogs.

There's no way for dog owners to know if their pets have heartworm disease.

Veterinarians, like Dr. Jed Rogers at the Firehouse Animal Hospital, are now recommending year-round treatment rather than just a 6-month period.

"Mainly because we're seeing more mosquitoes, and that's what transmits heartworm disease," Rogers said.

Infected mosquitoes bite a dog, mosquito larvae grows in the dog's bloodstream, and eventually worms as long as 14 inches multiply and suffocate their heart and lungs.

"Once you see the symptoms it's not necessarily too late, but by the time you see the symptoms, the disease has progressed a long way," Rogers said.

Treating heartworm disease can cost $1,000 and treatment alone can be deadly; while medicine to prevent the disease costs $80 to $100 to treat the average size dog for a whole year

"When we can spend a small amount of money to prevent a disease, that's the way to go," Rogers said.

The disease is deadly 100 percent of the time if left untreated. And when detected, treatment is almost always successful.

Symptoms of heartworm disease are coughing and shortness of breath. The preventive treatment also kills other parasite-borne illnesses like roundworm and ring worm. Those can be passed on to humans and can even become deadly in people with compromised immune systems.