There is a concept in medicine gaining in popularity and power. I first started hearing about "One Medicine" probably 3 years ago at veterinary conferences. Now I am hearing about it pretty much anywhere I go in veterinary circles. And in medical circles. It is the simple concept that we should not think of things as "veterinary medicine" and "human medicine." There is one medicine, and it applies to all of us.
Researchers have known this for quite some time, as the crossover between animal and human medicine is quite astounding. The sad fact is that many therapies are developed in animals (yes, some of them dogs), approved for humans, and then never taken through the regulatory hoops to be approved for the very animals in which they were developed. Vets use such therapies "off label" (meaning without official approval).
Mostly, the dogs used for such studies are actually suffering from the diseases being studied. They are not laboratory dogs, but owned dogs living in regular homes like yours and mine, but suffering from some disease that has a current study. Dog owners living close enough to the researcher, or able to conduct trials long distance, or willing to travel enroll in the studies. The dogs generally receive the therapy under study, plus some variety of tests.
The very first cancer vaccine was developed in dogs. The last I heard it was in human clinical trials.
The drug Restasis, for humans who don't produce enough tears, was developed in dogs, particularly the University of Georgia mascot, Uga (I forget which number Uga).
A therapy restoring sight to blind individuals was developed in dogs (Briards, I think) and has been used with a small number of humans.
Cancer researchers in particular are very prone to using canine study subjects, as our dogs share nearly all of our cancers with us.
The human and canine genomes are being constantly compared to find genetic markers for a wide variety of diseases.
So if, heaven forbid, your dog should ever develop some dire health problem, inquire if there might be a study that suits your circumstances. You never know who you might be helping in the long run.