Laboratory testing is not only important for determining why a pet is sick, but is a vital part of pre-anesthetic screening as well.  Periodic screening in apparently healthy pets is also important as some disorders are well advanced before outward symptoms become evident.  Here is a brief summary of what those tests tell us.

The Complete Blood Count is an evaluation of the red blood cells, white blood cells and the platelets.

  • The Red Blood Cells carry oxygen to the body and the brain, important for regular activity, but especially during anesthesia.
    • Decreases in the RBC count indicate anemia and results in weakness and increased anesthetic risks.  This may be an indication of undetected internal bleeding or chronic illnesses like kidney & liver disease or even cancer.
    • Elevated RBC numbers typically signify dehydration.
    • During times of illness, both conditions could be present and actually counteract each other enough to “appear normal”.
  • The White Blood Cells are made up of Neutrophils, Lymphocytes, Monocytes, Eosinophils and Basophils. They represent the body’s immune defense mechanisms.
    • Elevations are suggestive of infections, inflammation, hormonal disorders and some forms of cancer. Mild changes cans simply be a response to the stress of the hospital visit or even normal fluctuations.
    • Low counts can occur with overwhelming infections and bone marrow problems.
    • Some localized infections may not trigger a dramatic change in the WBC count if the body does not feel overly threatened or the infection is isolated from the circulating blood stream.
  • Platelets are the body’s first defense against hemorrhage from trauma and surgery.  It is important to know that there are sufficient platelets incirculation prior to invasive surgical procedures.

The Chemistry Profile evaluates the composition of the plasma in which the blood cells float. Chemicals from the internal organs are released into the plasma during metabolism and are indications of the general health of those organs. Normal levels help rule out conditions like kidney disease, liver disease, diabetes, pancreatitis, electrolyte imbalances and dehydration. Subtle fluctuations may require more specific tests to determine their significance in relation to particular organ dysfunctions. 

Urinalysis evaluates the ability of the kidneys to maintain proper water balance in the body.  The presence of crystals, glucose, bacteria, cells and casts may indicate other problems in the body that are manifested in the urine.

Thyroid Screening tests are often combined with the above tests in senior pets since many pets develop thyroid-related illnesses as they age.  Dogs tend to lose the ability to produce adequate levels of the thyroid hormones, while cats develop enlarged glands that produce excessive hormones.  It is important to keep these properly balanced. 

The Pet Health Network has additional information on the importance of pre-surgical blood tests.