Methemoglobinemia (Anemia) is a genetic disease of dogs characterized by increased circulating methemoglobin.
The aim of hemoglobin in the blood is to carry oxygen from the lungs to other parts of the body. 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. Under normal conditions, methemoglobin is converted back to hemoglobin, and a balance is maintained. But when there is too much methemoglobin in the blood, inadequate oxygenation of bodily tissues ensues. A visible sign of methemoglobinemia is when the blood becomes brownish in color, instead of the normal oxygen rich red color. Methemoglobinemia can be the result of a genetic disorder, or it can be caused by later exposure to certain chemical agents.
Methemoglobin reductase has been recognized in the Beagle, Chihuahua, Borzoi, English Setter, Poodle, Corgi and Pomeranian
- Rapid breathing
- Discoloration of skin and mucous membranes
- Swelling of face or jaw
Topical anesthetics such as benzocaine
Your veterinarian will want to know whether your dog has ingested acetaminophen or ibuprofen, or whether you have applied a topical medication. Blood tests may also be done at a laboratory to examine the levels of methemoglobins. If the methemoglobinemia is chronic, it is likely that the blood test will reveal a high volume of red blood cells. On the other hand, if the anemia is severe, or the cause is exposure to drugs such as acetaminophen, ibuprofen, or a topical medication, the veterinarian will look for evidence of organ injury.
A spot test may be performed where a drop of the dogs blood will be placed on an absorbent white paper and a drop of normal blood will be placed next to it. If the animal is suffering from methemoglobinemia, its blood will be noticeably browner than the bright red of the normal blood spot.
Mild to moderate no treatment necessary
If drug-induced, discontinuation of the drug
Acetaminophen or ibuprofen overdose vomiting induced immediately
Inherited animals have normal life expectancy and do not require treatment
Severely anemic blood transfusions
Electrolyte imbalances resulting from vomiting, diarrhea, kidney injury, or impending shock may be treated with IVs
In cases of severe anemia, methylene blue may be administered intravenously to reduce the methemoglobin count
Methemoglobinemia Living and Management
Exercise extreme care when using acetaminophen and ibuprofen medications. If your pet has ingested them by accident, induce vomiting and take it to the veterinarian immediately. If you are giving your pet ibuprofen for pain, be alert for symptoms of anemia. Color should return to the skin and mucous membranes once the amount of methemoglobin in the blood has returned to a level that is not critical, and blood on the spot test appears bright red. If methylene blue treatment has been given, the proportion of red cells in the blood should be monitored closely.