Heartworm is ONLY spread through infected mosquitoes.
So even though your dog doesn't go outside (which it should for walks/bathroom/ and play time) whenever you open a door a mosquito is bound to come inside one time or another.
Your just rolling the dice having yoru dog unprotected and an infected mosquito comes in a bites your pup.
Here, we have already had a few Positive results come back and its a LONG and drawn out recovery period(depending on how infested the dog is).
For a test, we only do it one way and its a simple blood draw from either a leg or the jugular. Fairly painless as well and very very quick. Its sent out to the lab and then we usually get the results back within 24 hours, sometimes less.
We dont dispense prevenative here unless the dog has HAD a Heartworm test, as some of the prevenative can cause more harm IF the dog is positive.
My dog Riot, is on year round prevenative. From December to April he is on Interceptor and from May to November he is on Revolution.
It all depends on what you'd like to protect your dog from as well. Usually if cost is a factor its Interceptor which covers all intestinal parasites(minus tape worm) and including heartworm.
Definately get your dog checked..
Its better to be safe then sorry...
IF, by chance your dog is positive and you keep procrastinating it might be too late to treat.
Let us know how things go!!