Methemoglobinemia in Cats

Ingesting an onion or inhaling an empty Tylenol bottle can cause Methemoglobinemia--a potentially deadly condition in cats. Be careful of what you expose kitty to, and do not let her play with empty pill bottles.

  1. Definition

    • Methemoglobinemia occurs when large amounts of methemoglobin collect in the cat's blood. When the level of methemoglobin gets higher than hemoglobin, organs become oxygen-deprived and hypoxic injury occurs. Methemoglobinemia also results in Heinz body anemia.

    Causes

    • Ingesting or inhaling toxic substances like Acetaminophen, pain medication for headaches, will kill cats. Also potentially fatal to cats are Benzocaine, an analgesic in topical creams and sprays; Phenazopyridine, a pain reliever for the urinary tract; Naphthalene and paradichlorobenzene, found in toilet-bowl cleaners; moth balls, moth crystals and moth cakes; and Thiosulfates found in raw, cooked or dehydrated onions. Methemoglobinemia may also be caused by an inherited condition called methemoglobin reductase deficiency.

    Symptoms

    • Symptoms include vomiting, anorexia, diarrhea, seizures, subcutaneous edema (especially in the face), salivating, brown or blue gums, loss of appetite, lethargy, coma and death. Cats with Heinz body hemolytic anemia will also have hemoglobinuria, in which hemoglobin appears in the urine.

    Treatment

    • Remove the toxin or medication and always consult your vet. No treatment may be necessary if methemoglobinemia is mild or moderate. If kitty has an inherited methemoglobin reductase deficiency, no treatment is necessary. Methylene blue can be given for severe cases, and blood transfusions should be given to cats with severe anemia.

    Prognosis

    • When caught early, kitty can recover and live a long life. Coma and death will occur when methemoglobin reaches 80 percent; this can happen with just one acetaminophen pill.