Kirby went in this morning for his first heartworm treatment, which consists of a shot of an arsenic-based compound that kills the heartworm. The shot, which was given in his lower back, is painful, I'm told, based on the location. That seems pretty consistent with Kirby's reaction so far -- he keeps biting and licking at the injection site. The vet has him on prednisone for a while, I guess to reduce inflammation.
Other than the injection site irritation, Kirby is a bit low energy, but otherwise OK. He's on strict "no jumping" orders, and so far he hasn't even attempted to leave the ground. He's asleep under my desk.
Now we just wait and watch for any signs of difficult breathing or other reactions. As I've noted before, I'm told the most dangerous part of this is if a worm breaks off and goes through the blood stream it can cause a blockage somewhere. So let's hope those worms hang on until Kirby's body can eliminate them micro-bit by micro-bit.
So far so good.