When this blog post was originally published (2009), hereditary conditions were excluded from coverage by some pet insurance companies. Today, virtually every company covers these conditions, but some have extended waiting periods for certain conditions like hip dysplasia. Be sure to read a sample policy to see if there are any restrictions.
To realize why I think this is an important factor to consider when choosing a company to insure your pet, take a look at these lists of conditions that are considered hereditary for each breed. The length of the lists may surprise you.
Also listen to this explanation by Laura Bennett, CoFounder of Embrace pet insurance company: