Anemia is a relatively common finding in avian and exotic pet medicine. Anemia is defined as a reduction in the number of red blood cells in the circulation. A veterinarian may suspect anemia by noticing pale mucous membranes, however blood tests such as a compete blood count (CBC) or packed cell volume (PCV) are required to determine the actual degree of anemia. These tests may also be the only way to detect anemia in mild to moderate cases in which pale color may not be apparent. Red blood cells are critical for carrying oxygen to every cell of the body. Low levels of red blood cells can lead to weakness, lethargy, fainting and in severe cases death.
Anemia is not truly a diagnosis in and of itself. There are many possible causes of anemia, some of which are easily diagnosed and some of which are much harder to diagnose.
Broadly speaking anemia can occur one of three ways:
- Loss of red blood cells: The most obvious of which is blood loss (bleeding) following trauma, however blood can also be lost in less obvious ways through the bowel and urogenital system.
- Destruction of red blood cell: Animals may eat certain toxins such as lead (common in older household paint), zinc (found in some bird toys and household items), or onions which can cause red blood cells to rupture within the bloodstream. It takes time for these ruptured cells to be replaced, and in the meantime anemia can develop. Another type of destructive anemia can occur when an animal’s immune system targets red blood cells and destroys them. Fortunately this type of anemia is very rare in avian and exotic pet medicine. Diagnosis of this last form is difficult and may require advanced diagnostic tests.
- Decreased production of red blood cells: One relatively common cause of decreased production of red blood cells is iron deficiency. This can occur when pets are on substandard diets. Diagnosis and treatment of this condition must be made by a veterinarian since excess iron supplementation may be toxic. Chronic inflammatory or infections disease may also lead to this type of anemia.
If an animal is found to have anemia, a thorough physical examination and discussion of the pet’s dietary and housing history must be undertaken. Additional tests are often required to determine the source of the blood loss, or the cause of red cell destruction.
Such tests may include:
- Fecal occult blood test: Sometimes blood loss in the stool is not apparent to the naked eye. This test is performed at a laboratory and involves chemical tests to determine if microscopic amounts of blood are present in the stool. Even microscopic loss of blood from the bowel may be significant, especially if it occurs for a prolonged period of time.
- Urinalysis: A microscopic examination of a patient’s urine may allow for the detection of small amounts of blood in an animal’s urine. Additionally, this test may allow us to determine the cause of blood loss in the urine such as evidence of a bladder stone or severe bladder infection. While not traditionally performed in birds, this test can be used, particularly in larger avian species.
- X-rays: One or two views may be required. This test can be very useful in cases of anemia secondary to foreign material, such as metal. Metal can cause anemia two ways: by directly damaging the bowl and causing bleeding, and by leading to red cell destruction within the bloodstream due to toxic damage to the cells. Unfortunately not all foreign objects will be revealed with regular X-rays, and more advanced tests such as contrast enhanced X-rays, ultrasound or endoscopy may be required.
- Chemistry panel: This test will allow for evaluation of the animal’s organ function and may allow the veterinarian to determine the underlying cause of the anemia. For example the chemistry panel may detect liver disease, which can explain anemia since the liver is responsible for the production of many clotting factors.
- Lead test: A small amount of blood can be drawn and submitted to the laboratory to determine the amount of lead within the bloodstream. Lead can cause a wide variety of clinical signs ranging form severe seizures and neurological disease through milder signs such as anorexia. Anemia can occur alone or in conjunction with any of these signs. There are many different sources of lead in the home. Almost all apartments and houses older than 30 years will have some lead based paint. Even if the house has been repainted it is unlikely that complete lead removal was performed. Lead is also found in some imported toys, antique toys and cages, leaded glass and mirrors and curtain weights.
- Zinc testing: As with lead, a small amount of blood can be used to diagnoses zinc toxicity. Also as with lead, zinc can cause anemia alone or a variety of other clinical signs such as altered urine production, altered bowel habits, weakness and lethargy. Zinc can be found in some cheaper bird toys, certain types of bird cages and many household metals such as staples, paperclips, and zippers.
In addition to the above tests, your veterinarian may need to consider more advanced and less common tests such as advanced clinical pathology tests or a referral for a CT scan.
In conclusion, anemia is a relatively common finding among avian and exotic patients. The condition can range from mild, and relatively incidental to severe and potentially life threatening. The decision upon how to proceed with achieving a diagnosis of the underlying cause of a pet’s anemia will be made by the owner and veterinarians by considering the degree of anemia and the pet’s clinical signs.