There is no shortage of the machines or diagnostic equipment, in fact the increase in demand for animal testing probably lowers the cost of manufacturing. As long as the individual pet owner is the one shelling out the money for the procedures I don't see how any of it takes away from resources available to humans.
Seriously, who cares? With the amount of stray cats running around any given neighborhood, I find it hard to give a crapola about a kittty who can't remember where it's litter box is. For freak's sake already. More concern should be surrounding those morons who own uteruses and leave newborn babies in trash cans...not psycho kittens or old-timer felines.