I was at a veterinary clinic recently with a dog I was dog-sitting; he had a foxtail (grass seed awn) in his ear. I overheard someone responding to the vet tech’s questions regarding another patient.
“Is he on heartworm prevention?”
“No, it lapsed.”
I shivered involuntarily. Where I live, heartworm is rife in the local dog population. And it not only affects the lives of many dogs – especially because in this relatively poor area, many owners can’t afford to treat dogs who get infected with heartworm – but also greatly affects the number of dogs that my local shelter can save. The shelter receives many heartworm-positive dogs, and can’t possibly afford to treat them all. Instead, they have to triage the heartworm cases – how severe is the infection, how old is the dog, how is the dog’s overall health, how adoptable does he seem?
Many dogs can live with a mild heartworm infection, especially if they are kept on heartworm preventatives afterward, so they don’t become infected with any more worms than they originally developed.
But in the cases where the infection is severe – well, there are few worse sights. The dog gets extremely exercise intolerant; he may start coughing and wobbling from the exertion of getting up from a nap and walking to his water bowl. The problem is two-fold: his heart can’t work efficiently to pump oxygen throughout his body, due to the mechanical blockages of the worms residing in his heart and major blood vessels; because his heart is compromised, the lungs become congested and full of fluid.
Heartworm preventatives are expensive, especially if you own more than one dog; I get it. But I dare anyone who lives in an area with a lot of heartworm to visit with a dog with a heavy infection. Spend five minutes with a middle-aged dog who is swollen with edema, coughing and gasping for breath, and you’d never let your dog’s prescription lapse.
There is a good interactive map that shows the average prevalence of heartworm infections in the United States. You can click on your state, and then click county-by-county for further breakdowns. In some states (mine and maybe yours), varied terrain and weather/moisture conditions mean that the infection rate may be zero in some areas and quite high in others.
Past in-depth articles in WDJ about heartworm prevention: