Your Bird's Bill of Health
Dr. Don Harris
Even the most healthy-looking bird can harbor hidden disease, and lab tests are the best way to find out how healthy your bird is. Some procedures provide information about the animal's general condition; others are more specific. It is important that your veterinarian evaluate all major aspects of your bird's health.
If the tests only examine the isolated problem, an underlying and possibly more serious illness may be overlooked. Here's an idea of the tests your veterinarian may order when you bring your bird in for a physical.
Checking the Immune System
The single most important test for almost all avian patients is the Complete Blood Count, or CBC. The test is divided into several parts, detailing the activity of certain parts of the immune system and providing information on blood conditions. The test may uncover many types of infections, anemia, parasitism and other conditions even when a bird appears perfectly normal.
Electrophoresis (EPH, SPE) is a test that examines another part of the immune system, measuring particular proteins in the blood and providing information on certain immune responses. Changes in specific proteins suggest the presence of certain physiologic or pathologic processes, and the test can reveal many conditions that would otherwise go undetected. It also serves to strongly support or contradict diagnoses revealed by other tests. Chlamydiosis, a bacterial infection, is one disease in which the EPH helps tremendously in establishing a diagnosis.
A Look at the Liver
Because the liver is commonly involved in both infectious and metabolic diseases, two tests are quite useful in the avian profile. The AST (also called SGOT) is a measure of liver (and muscle) damage, while the bile acids test assesses liver function. Both are necessary to pinpoint disease since a damaged liver may still function satisfactorily, and a liver may be dysfunctional but not display damage. Many diseases, such as viral infections and Chlamydiosis, damage the liver while other disorders, such as malnutrition, affect liver function.
Several factors can complicate a diagnosis, and several tests may be required to pinpoint the source of a problem. For example, because muscle damage can affect results of the AST, a test for another biochemical – known as CK (or CPK) – is used to discover why AST is elevated. CK (or CPK) is released by damaged muscles and nerves. So, if an AST alone is elevated, the source of the problem is probably the liver; if the AST and CK are both elevated, the source is probably muscular. If the CK alone is elevated the source is likely to be nerve tissue. Note that this is a simplification and that combination problems also occur, further complicating a diagnosis.
There is no blood test that directly assesses kidney damage, but the uric acid test indirectly measures kidney function. Many times, subtle kidney damage is not recognized until so much damage has occurred that the function is compromised. Because of this, most abnormal uric acid findings imply very serious – sometimes terminal – disease. A urine analysis can demonstrate evidence of kidney disease at earlier stages; however technical skill is necessary to extract diagnostic information from avian urine samples, because the urine is usually mixed with feces.
Blood calcium levels can reveal aspects of the bird's diet, vitamin status, husbandry and reproductive status in females. For example, a low calcium level in an African grey often means the bird is not being exposed to enough natural sunlight.
Blood glucose (blood sugar) rises moderately with stress and significantly in diabetes. Critically low blood glucose is usually a grave sign and death is often imminent.
Testing for Parasites
Analysis of a bird's droppings provides varying degrees of information. Tests currently used to screen for parasites, abnormal bacteria, and yeast are highly subjective. The bacterial culture and sensitivity test provides a more accurate picture of the microbiological population within the bird's digestive tract, but much care is necessary in interpreting the information it provides. Negative findings with any of these tests do not conclusively eliminate the possibility of the conditions for which they screen. For example, the absence of parasites in a stool sample does not guarantee that the patient is parasite-free; other tests such as the CBC may however suggest parasites and warrant further investigation.
Psittacosis, polyoma virus infection, and psittacine beak and feather disease can be specifically tested for, in some cases through more than one test. While most of these tests are legitimate, they all share the same problem: neither positive nor negative findings are 100 percent accurate. All findings must be supported with appropriate clinical and laboratory data. Without several kinds of data to illustrate a complete picture, any findings may be misleading.
Many other tests exist to investigate the health of pet birds. Experience is the best guide to knowing which tests are appropriate in a given situation.