Borax is not safe for pets to ingest, but it is used in many topical treatments, including flea killers. Borax, or sodium borate, is commonly used as a detergent and pesticide, but it can be extremely harmful to pets and humans if it is swallowed.
Pets that ingest borax might exhibit gastrointestinal symptoms, such as vomiting, diarrhea and abdominal discomfort. Owners who believe their pets have ingested borax should take the animal to a veterinarian immediately for treatment.
Borax can also cause skin irritation. Pets with dry, red or inflamed skin might be suffering from borax poisoning, but these symptoms can be caused by many other irritants. An official diagnosis from a veterinarian is the best course of action.