Methaemoglobinaemia caused by hydroxycarbamide (hydroxyurea) ingestion in a dog.

A three-year-old female neutered greyhound was presented after ingestion of its owner's hydroxycarbamide (hydroxyurea) tablets. The dog was found to be cyanosed, and methaemoglobinaemia was demonstrated by co-oximetry. Therapy included methylene blue, oxygen, packed red blood cell transfusion, N-acetylcysteine and crystalloid fluids. Methaemoglobinaemia resolved within 16 hours. Granulocyte colony-stimulating factor was administered for five days in an attempt to prevent severe neutropenia. Mild delayed transient myelotoxicity was suspected. The dog made a full recovery.