Pet health insurance can definitely be worth the investment if you take the time to select the right policy. Pet health insurance helps to cover all of your pet's medical costs including ongoing checkups and shots as well as emergency medical care. As your pet gets older and becomes more likely to get ill, you may find that you make more use of your pet health insurance. However even young pets can require a lot of medical care (for example, dogs that frequently chew things up may need surgery for getting items lodged in their stomachs). If you're the kind of person who regularly takes your pet in for the care that they need (which good pet owners do) then the insurance investment can definitely be worth it.
I've got a hub that outlines four reasons to get pet insurance (http://hubpages.com/hub/Four-Reasons-for-Pet-Healt... It explains that there are soooo many different reasons a pet may need to go to the vet and each time this costs you money. Each visit can be cheaper with pet insurance.
As with any other type of insurance, though, it's important to look at all of the different plans and their costs to make sure that you get the right amount of pet insurance coverage at a fair and affordable price.