More serious NSAID complications include stomach or intestinal ulceration and bleeding, kidney injury, and less commonly concerning liver enzyme changes. Black, tar-like stool, repeated vomiting, or sudden collapse are urgent signs because they can reflect bleeding or severe dehydration. Kidney stress can look like increased thirst and urination at first, then reduced urination and marked lethargy if it progresses.
Rare but severe intestinal complications have been reported in dogs after meloxicam, including colonic perforation, which is why persistent abdominal pain, straining, or a suddenly very ill dog should never be watched at home “to see if it passes” (Longley, 2022). Owners do not need to diagnose the cause; they only need to recognize that these are emergency patterns. When in doubt, the safest move is contacting an emergency clinic with the medication name, dose timing, and symptoms.