Question: what medicine can i give my dog for colitis?
Answer: Sulfasalazine is composed of sulfapyridine and 5-aminosalicylic acid (mesalamine) joined by an azo bond. ... 
Metronidazole has fair efficacy against Giardia, and it is also efficacious in some cases of diarrhea in which giardiasis was not definitively diagnosed.