Disease overview

Methemoglobinaemia is a blood condition in which too much methemoglobin is in the body. Hemoglobin is the essential oxygen carrier in the blood; it has iron, which acts as the binding side for oxygen. Methemoglobinaemia occurs when the iron-binding sites are oxidized, which creates methemoglobin and prevents oxygen from attaching to the site. This leads to deficient oxygen supply for the body.

Gene name

CYB5R3

Inheritance

Autosomal recessive

Signs and symptoms

Clinical signs of respiratory distress may include rapid respiratory rate, increased heart rate, and exercise intolerance. Since the blood is not carrying enough oxygen, the gums may appear blue or blueish-purple (cyanotic). These signs usually manifest with other diseases such as a respiratory infection that may exacerbate the condition into showing signs.

How is it diagnosed

A veterinarian will conduct a thorough exam, including a review of health history and any clinical signs. Laboratory tests, such as blood gas analysis, will aid in diagnosis. There are certain toxins that can cause this condition; therefore, genetic testing may need to be conducted to rule out a genetic cause.

Breeds at higher risk

Citations

Jaffey JA, Harmon MR, Villani NA, Creighton EK, Johnson GS, Giger U, Dodam JR. Long-term Treatment with Methylene Blue in a Dog with Hereditary Methemoglobinemia Caused by Cytochrome b5 Reductase Deficiency. J Vet Intern Med. 2017 Nov;31(6):1860-1865. doi: 10.1111/jvim.14843. Epub 2017 Sep 29. PMID: 28963729; PMCID: PMC5697180.

Disclaimer

Disease diagnosis and treatment should always be performed by a veterinarian. The following information is for educational purposes only.