Because I am a stickler for accuracy in language: If they’re a mix, then they aren’t purebred. The word “purebred” means an animal bred from parents of the same breed or variety. Because you have two different breeds involved, they are a mix.
That said…do they go outside? Have you taken a fecal sample to the vet annually? I give heartworm preventative 4x a year – my old man cat doesn’t go outside, and I get annual fecal and blood testing done for him. Get fecals and blood panels done, at the very least, to make sure everything’s good. Without a full picture of your cats’ health, you cannot make an educated decision on how to handle medications and the like.
Hello,
Yes hookworms can be a bugger to eradicate. Ask your vet for help with either someone from the lab services company they use to send diagnostics to, or help from the vet at the manufacturers company you buy your Heartworm prevention from (if it is labeled for hook worms). After rhat a second opinion with an internal medicine person might be helpful just to make sure it isn’t anything else. Or being exacerbated by something else. Often it isn’t just one problem. It can be others too. I hope this helps.