Can I Feed My Dog Watercress?

Can I Feed My Dog Watercress? Although watercress itself is not particularly toxic to your pet, it can cause nausea, vomiting, and diarrhea in large doses. Is watercress poisonous to cats? Nasturtium watercress is only mildly toxic to felines as the symptoms associated with poisoning are limited to gastrointestinal upset. Are dogs allowed salad cress?