Gave My Puppy Too Much Wormer. Use care when administering dewormers to your pet. Common signs associated with excessive ingestion of most paste wormers include lack of appetite, drooling, diarrhea, vomiting, lethargy, and weakness.
While it is unlikely a horse will become ill or suffer harmful effects from being dewormed too often, in the long term, all horses ' health can be compromised by the development of parasite resistance to dewormers. You can call your vet or, in the states, the aspca's animal poison control hotline (there's usually a fee. Too much of certain types of wormers can also bring about organ problems—even organ failure—and potentially even death.