Methemoglobinemia is a genetic disease of dogs characterized by increased circulating methemoglobin.
This condition can be caused by:
- Acetaminophen toxicity
- Genetic deficiency in methemoglobin reductase enzyme
Methemoglobinemia causes reduced oxygen carrying capacity of the blood because methemoglobin cannot bind oxygen. If methemoglobin content reaches high values (> 50% of total hemoglobin), various organs may suffer hypoxic injury.
Diagnosis is based on enzyme assays for assessment of methemoglobin reductase enzyme levels.
Emergency treatment of affected dogs may require methylene blue, given slowly over several minutes as a 1% solution (1 mg/kg IV). A dramatic response should occur during the first 30 minutes after treatment.
- Srivastava S et al (2002) Methemoglobin reductase activity and in vitro sensitivity towards oxidant induced methemoglobinemia in swiss mice and beagle dogs erythrocytes. Mol Cell Biochem 232(1-2):81-85
- Fine DM et al (1999) Cyanosis and congenital methemoglobinemia in a puppy. J Am Anim Hosp Assoc 35(1):33-35
- Harvey JW et al (1974) Methemoglobin reductase deficiency in a dog. J Am Vet Med Assoc 164(10):1030-1033
- Harvey JW (1996) Congenital erythrocyte enzyme deficiencies. Vet Clin North Am Small Anim Pract 26(5):1003-1011