Familial Congenital Methemoglobinemia (MetHg)
Methemoglobinemia (Methaemoglobinemia) is an inherited disease affecting the Pomerianian breed. It is characterized by an increase in the concentration of oxidized hemoglobin in the blood.
A variant in the CYB5R3 gene was found in Pomeranians to cause methemoglobinemia (MetHg).
Methemoglobin impairs the normal transport of oxygen to the tissues, leading to cyanosis (bluish-purple hue to the skin) and exercise intolerance. Other symptomps seen include coughing, shortness of breath and increased heart rate. 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.
Prevalence, we currently don't have information about the prevalence of this variant in the breed.
