Zinc oxide ointment can cause clinical signs quickly, but it is typically something that can be managed at home. Ointments typically contain 10-40% zinc oxide, and if ingested typically cause GI irritation and vomiting.
The ASPCA Animal Poison Control Center reports that rarely a hypersensitivity reaction (erythma, urticaria, facial edema) to the zinc can be seen secondary to ingestion of the zinc oxide.
These ointments typically contain emollients that can cause a laxative effect as well, resulting in a greasy, oily diarrhea. It is uncommon, though possible, to see zinc toxicosis in large ingestions, though emesis is often very productive at removing this from the GI tract, and the zinc is often not well absorbed in the ointment form.
Any pets who ingest zinc oxide ointment should be monitored for GI upset. Fluids may be required if pets have GI upset that is significant enough to cause dehydration. Hypersensitivity reactions may require treatment with antihistamines and corticosteroids.