Monitor for cyanosis and methemoglobinemia (chocolate-brown mucous membranes, dark-brown blood), which can occur within a
few hours after exposure. Also monitor for delayed myelosuppression and thrombocytopenia by performing a baseline complete
blood count and serum chemistry profile and then repeating these tests on days 3 and 7 after treatment is initiated. In addition,
monitor the patient's hematocrit and liver and kidney function.
Acute hydroxyurea toxicosis in animals can result in serious and life-threatening clinical signs of methemoglobinemia and
myelosuppression. Prompt and aggressive treatment is indicated to help ensure a successful outcome.
"Toxicology Brief" was contributed by Safdar A. Khan, DVM, MS, PhD, DABVT, ASPCA Animal Poison Control Center, 1717 S. Philo
Road, Suite 36, Urbana, IL 61802. The department editor is Petra Volmer, DVM, MS, DABVT, DABT.
1. Wray JD. Methaemoglobinaemia caused by hydroxycarbamide (hydroxyurea) ingestion in a dog. J Small Animal Pract 2008;49:211-215.
2. Plumb DC. Veterinary drug handbook. 5th edition. Ames: Iowa State University Press, 2005;401-402.
3. Hydroxyurea. In: POISINDEX System [intranet database]. Version 5.1. Greenwood Village, Colo: Thomson Reuters (Healthcare)
4. Hydroxyurea. AHFS Drug Information 2008. American Society of Health-System Pharmacists, American Hospital Formulary Service, 2008;1083-1089.
5. Marconato L, Bonfanti U, Fileccia I. Unusual dermatological toxicity of hydroxyurea in two dogs with spontaneously occurring
tumours. J Small Animal Pract 2007;48:514-517.
6. AnTox Database. Urbana, Ill: ASPCA Animal Poison Control Center, 2003-2010.