I saw two pit bulls today.
Both had been off their heartworm preventive for quite a long time.
One’s heartworm test came up positive, the other was negative.
“Why?” you ask. Several factors are probably in play.
The biggest is probably mosquito population in the vicinity of where each dog lives. Proximity to a swamp, lake, pond, wetland or river tends to increase the mosquito population. We have had low rainfall for much of the year here on the Mississippi Gulf Coast. Still, there are always places where water stands and mosquitos will thrive.
In the last two weeks we have had abundant rainfall, and the mosquito population has blossomed proportionately.
All mosquitos are not created equal. Some species carry and transmit heartworms better than others. If the environment around your home supports some species of mosquito to the detriment of other species, it can influence your pet’s likelihood of contracting heartworms.
Red Boy, the dog with a positive heartworm test, is primarily an outdoor dog. Rosko, whose test was negative, is primarily indoors.
That, alone, however, is not anything to depend on. The mosquito that carries heartworms best also likes the indoor environment. One’s pet need never even go outdoors to contract heartworms. Some mosquitos are happy to deliver at no extra charge.
Some dogs and some cats may have a natural, partial immunity to heartworms. Further illumination of that process may lead to a vaccination for heartworms one day. Still, natural immunity is not even a proven process and certainly cannot be depended upon to keep your pet free from heartworms.
Neither of these dogs should ever have been off heartworm preventive. Just because Rosko’s heartworm test was negative today doesn’t mean he can skip doses of heartworm preventive safely.
We’ve said it many times, but it bears repeating: Every dog and every cat need and deserve to be on heartworm preventive.See you tomorrow, Dr. Randolph.