It all comes down to replacement cost of the animal. Only high value animals will even get biopsies because many times it is cheaper to replace the animal than to go through a workup. A good horse is expensive to start with and then you put a lot of money into training them so it makes sense to biopsy them. Other than that and house pets, there is not a high demand for vet pathology.
This isn't true in the least.
I'm a veterinary pathologist, and there is more than adequate demand for us both in academia and industry (not to mention research and gov't), both anatomic and clinical (AP and CP are completely separate specialties in vet med because there is simply too much species variation to be able to combine them into one three-year residency, although I do know of several double-boarded veterinary pathologists who just did one and later, the other).
Biopsy, necropsy, histo, IHC, etc. are done all the time on all sorts of animals, not just special/expensive ones and certainly not just house pets. Our academic hospital takes well over a thousand necropsies a year (this year has been especially nuts, we're up to over 700 since January so far), which we usually do full histology of relevant tissues on as well as, if warranted, bacteriology, molecular diagnostics, tox, you name it. Many more biopsies a year as well, I'd have to check the log. May not seem like that much to a large human hospital - I have no idea of your caseload - but it keeps us pretty busy.
Money isn't too bad, either. Vet med usually pays pretty ****ty (starting salary for a general practitioner is about 60-65K, with 150-200k of debt) but with residency, board certification, and usually an additional research fellowship if you want to go academia/professor track under your belt, you can make anywhere from 100-150k in pathology depending on if you go into academia or industry. It's a small specialty compared to surgery and IM and such, but we tend to not have issues finding jobs anyways.
I love my job. You wouldn't believe the crazy species and lesions we see. Of course, animals get a lot of the same diseases as humans do, but it is the species variety on top of the disease variety that keeps me interested. We do everything. Companion animals, food animals, equines, exotics, wildlife, camelids, swine, avian species, laboratory animals, you name it.
