I am the proud owner of 3 dogs and a cat. Shortly after I adopted my pug puppy, he jumped off a step and broke his growth plate, requiring surgery. It cost me over $3,000 out of my own pocket. I decided then and there to purchase insurance from ASPCA.
About 10 months later, my cat got sick and it turned out she had a golfball sized struvite stone in her bladder. For a 4 pound cat, that was giant. We had her surgery, and made the claim to ASPCA. Within 4 weeks, we were reimbursed and the entire incident only cost us about $150 out of pocket. Not 6 months later, my border collie required surgery for struvite stones.
If you love your pet and plan to provide good medical care for them, you're asking for trouble by not carrying insurance.