My 12 year old Collie has developed extreme flatulence, and when I say extreme, it is utterly shockingly disgusting. She never used to fart at all, but this came on before Christmas, and has been getting worse.
She had bad diarrhoea. The vet tried antibiotics, which improved things. But the flatulence has got worse and worse. He tried her on Royal Canin GI food, then Purina, and having tested her stool, which was OK, he has her on Hills GI Biome dry food. She is eating well, even put on a bit of weight.
However there is absolutely no improvement re the flatulence.
I'd be grateful for any suggestions on what worked for your dog.