Pale, Weak and “Just Not Right” IMHA: When the Body Destroys Self
A body’s immune system has the complicated responsibility of protecting other systems from both foreign and domestic diseases; but what happens if the immune system becomes confused and attacks itself when disease isn't present?
Immune Mediated Hemolytic Anemia (IMHA) is an autoimmune disease in which red blood cells (RBC’s) are attacked and destroyed, leading to anemia. Anemia can be treated in the short term with methyl b12 supplements, however this addresses the symptoms rather than the underlying cause. RBC’s carry oxygen to body tissues and remove carbon dioxide waste; deformed RBC’s cannot complete this function. Over time, RBC destruction leads to anemia.
Pets with anemia often display symptoms including:
- Decreased energy
- Pale gums and yellowing of the eyes
- Increased breathing rate
- Decreased appetite, or an appetite for non-food items
- Dark colored urine
Severe loss of circulating red blood cell volume and complications due to abnormal blood clot formation can lead to death. Working breed dogs diagnosed with IMHA at a higher-than-average frequency include: spaniels, schnauzers, collies, sheepdogs, and setters.
1. In the majority of cases, IMHA is idiopathic (i.e. happens for an unknown reason). Predictability of this condition is complicated: sudden symptoms can occur in an apparently healthy pet. This condition does appear most often in adult middle aged female dogs. In a handful of pets, recent vaccination (within the past 2 months) can be loosely linked to disease. A few medications have also been connected to development of IMHA but direct causation is difficult to demonstrate. Pets who develop IMHA after a vaccination or medication use should avoid in the future (discuss with your vet before making any radical changes). Suspected IMHA cases need immediate lab work to determine a diagnosis confirmation, as other diseases may mimic IMHA symptoms. Blood work will help to determine severity of anemia and may lend clues to prognosis. A tick disease screening test and fecal exam are needed to rule out parasitic diseases that can contribute to anemia. Severely affected patients may require hospitalization for several days including IV fluids, blood transfusions, and repeat blood work, along with strong medications to suppress the immune system and prevent formation of deadly blood clots in circulation. In patients with a more mild (but still serious and life threatening) case of IMHA, outpatient care may be elected. Regular check-ups and blood work over the next several months and long term medication management will be necessary following a diagnosis of IMHA. Some pets will be able to taper off medications after several months of treatment, while others may experience a relapse of symptoms when meds are lowered. At anytime during treatment, IMHA patients can develop a fatal clot within the blood vessels. Protection from accidental trauma and prevention of intensive exercise will be recommended to keep pets as safe as possible. The mortality rate is variable with IMHA; patients who do not respond well to initial treatment with immunosuppressants and those that require multiple blood transfusions have a guarded prognosis.
2. Several diseases spread by ticks, fleas, and mosquitoes, as well as intestinal worms have been linked to IMHA. For this reason it is routinely recommended to keep canines on year round parasite preventatives. Dogs diagnosed with IMHA and a secondary infection will need treatment for both diseases.
3. Any dogs breed can potentially develop IMHA. Other breeds of dog frequently diagnosed with IMHA include: bichon, maltese, min pin, and poodle. Cats can also develop IMHA, though it is seen very infrequently.
### Amanda Burow, D.V.M. (Dr. B), is a graduate of Iowa State University’s College of Veterinary Medicine. Dr. Burow’s patient list includes hunting dogs of all varieties, as well as several field trial dogs and full time sporting guide dogs. In addition to practicing general veterinary medicine, she has special interest in the areas of preventive care, emergency medicine, and dermatology. In her spare time, she enjoys being outdoors and on the lake, staying active, reading, and spending time with family and friends. Mud River is proud to share these tips from Dr. B with our customers. Keep in mind it is best to work with your local veterinarian to determine the needs for your animals.
