Hi, Welcome to JustAnswer. I am a licensed veterinarian and I'll do my best to be of assistance. Since Jasper is a hunter, he could be more prone to getting tapeworms. If by "frontal" you mean Drontal, then he is being dewormed of tapeworms every three months. However, there are other parasites that would not be susceptible to Drontal, so his big belly could be from worms.
Big bellies could also indicate that a cat is overweight, but it also could indicate that there is fluid accumulation in his abdomen which would indicate a systemic disease and not just parasites.
The best for Jasper would be to have your vet there examine him and possibly do a fecal test to check for intestinal parasites. An examination may also lead your vet to further diagnostics depending upon what is found.
Thank you for your response. I'm really glad that Jasper does feel well, but from your description I am concerned about ascites (or fluid accumulation in his abdomen) which could come from several different disease problems.
Fleas also do carry tapeworms, so he is on a great regimen for tapes. Other parasites include round worms, whip worms, hook worms, and coccidia. . .these are the most common but can vary depending upon your location.
Sorry to hear that your vet is ill. Since Jasper is feeling fine, then there really isn't an urgency to see another vet.
Unfortunately, I wouldn't know. . .I'm in California, but even here the parasites vary from region to region.
Your vet will know though for your region.
If Jasper does use a litter box, you could collect a fresh fecal sample and get it down to your vet's office. . .the techs are probably still available?
Yes, the regions do make a difference as far as contagious diseases, but animals are the same world wide.
You are very welcome. It does sound like Jasper has a lovely life! I hope that all is well with him.