Help with sick GP

  
Sampson

743580
 
 
Barked: Wed Nov 28, '12 2:25pm PST 
I have two GP that I love dearly. My male is 6.5 yrs. and has recently stopped eating a lot. He just lays around and gets thinner and thinner. Went from 135 to 104 lbs. Three vet visits, many blood tests, meds and he's still not much better. Vet thinks it's an intestinal problem but whatever is going on isn't getting any better. Vet is the best small animal vet in these parts. Any help?