We have a jackrussel/collie/whippit and he always looks reallt thin we worm him every 3 moths and he always has beef and buiscuits help please

Whippets are very thin! I suspect that he got the thin gene from that side of the family.
Why worm him every 3 months? Just because he's thin?

What does your vet say? Which breed does he most look like? Like mentioned whippets are thin, lean dogs. It could just be her genetic makeup. As long as she is on a quality food and healthy by any other standards, I wouldn't worry too much.

I have a boxer mix and she is very lean. People always comment about how thin she is. With a leaner breed it's commen to see their ribs, this is how they are SUPPPOSED to look. If your dog isn't starving and otherwise healthy, I wouldn't stress too much, leaner dogs usually end up being healthier dogs and are at a lesser risk for developing joint/muscle pain.