Methemoglobinemia (MetHg)

LABOKLIN Service ID: 8870

A variant in the CYB5R3 gene was found in Pomeranians to cause methemoglobinemia (MetHg). Methemoglobinemia is characterized as increase in the concentration of oxidized hemoglobin in the blood. Methemoglobin impairs the normal transport of oxygen to tissues, leading to cyanosis and exercise intolerance. Physical examination of affected dogs showed a bluish discoloration of dog’s oral mucous membranes, tongue, and lower abdominal skin, while no cardiac or pulmonary abnormalities were detected on auscultation. Blood examinations showed a notably lower b5R (NADH-cytochrome b5 reductase) level and the colour of the blood was much darker red to brownish compared to healthy dogs. During surgery, one affected dog’s percutaneous oxygen saturation fell to 90% (reference range, 96–100%), which could not be explained by surgical or anaesthetic complications.

Method	sequencing
Breed list	Pomeranian
Heredity	autosomal recessive
Duration	1 - 2 weeks after arrival of the sample