Do you even know how susceptible cats are to heartworm?
If there’s mosquitoes in dogs where you live, there’s mosquitoes in cats – it’s kind of that simple. One difference is that dogs can at least be treated for heartworm (which isn’t cheap); there is no treatment for cats. Some cats die of heartworm (second cause of sudden death in cats) and others can get sick (heartworm associated respiratory disease) and some cats appear fine, but are they really? They may suffer respiratory damage and not show symptoms.