5%

Shelby knows that something's wrong.

When her heart rate goes up -- when she gets excited because I've just come home, or she's finished pulling me up the last of the three flights of stairs to our condo -- she starts coughing, a horrible hacking wheeze that usually ends in a brutal, desperate attempt to spit out the obstruction in her chest. It's a frightening sound. It's the sound of the dead heartworms trying to kill her, even after they themselves have been dead for weeks.

I try to keep her calm. She isn't allowed to play; she can never be off leash, even inside the house. Most of her days are spent in the crate. Her walks are slow and dull affairs, although I've tried to enliven them a little by taking her to places where there are lots of interesting new smells. It helps, but not much. Shelby is a vibrant young dog: she's clever and curious and athletic. She wants to live, and she doesn't understand that all these restrictions are meant to help her do just that.

But even within the confines of her temporarily boring and limited life under treatment, sometimes her heart rate goes up. Then she coughs. And I get scared, and she gets scared.

I don't think she's picking it up from me. I think Shelby knows, in some wordless doggy fashion, that something is very seriously wrong in her body. And she comes to me, and buries her head in my lap and curls her chest around my legs, expecting that I will somehow make it okay.

And I stroke her neck and scratch her where she likes it, under her ears on the corners of her chin, and tell her that she's a good dog and I know she's scared but it's all right, it really is, everything will be okay. She wags her tail, listening. Eventually she relaxes. The coughing stops.

And I think: the vet told me there was a 95% chance Shelby would pull through treatment. She has a 95% chance of living a full, healthy, normal life once this month of confinement is over.

Those are good odds. They're very good odds.

But sometimes I think, while telling this dog she doesn't need to be afraid, that everything will be fine and the choking feeling in her chest will soon melt away: there's a 5% chance that I'm lying.