We purchased an impulse puppy, but we wanted to have everything just right for him. At $33/month, we figured insurance was a good idea. He jumped off the couch and face planted on day one, after all.
When diagnosed with luxating patella just after his first birthday, we were aghast (one strike against impulse buy!). And then... We learned that the best fix was surgery. The surgery was $2000, complete with medication and X-rays. That's per leg.
Both surgeries were done, less my $500 deductible, and a cheque in the mail covering 90% of the remaining cost. All done quickly and electronically. The people are so pleasant to deal with too!