Understanding the protocols around pre-testing preparation for our animal patients is crucial to ensure the accuracy of the results. One of these preparations is fasting, i.e., restraining the animal from consuming food for a specified period before testing. While not all tests require this, there are a few that do. Below is a guideline outlining the diagnostic tests that typically involve a fasting period of 10 to 12 hours:
Fasting NEEDED for these Tests:
- Blood Chemistry Panel: Fasting is necessary for tests involving glucose, liver enzymes, kidney function markers, lipids, and other components of the blood chemistry panel. Fasting helps minimize the potential influence of recently consumed food on these parameters.
- Thyroid Testing: Fasting helps prevent lipemic blood and allows proper interpretation of thyroid levels.
- Phenobarbital Testing: This test is typically performed to monitor patients after starting treatment for epilepsy or other seizure disorders. Fasting helps prevent lipemic blood and allows proper interpretation of phenobarbital levels. HOWEVER, patients must take their morning dose of phenobarbital with a small amount of food. This test doesn’t have to be performed within a certain period of the morning phenobarbital, but a patient must be on phenobarbital for at least two weeks before scheduling this test.
- Low-Dose Dexamethasone Testing: Fasting helps prevent lipemic blood and allows proper interpretation of cortisol levels. If patients are on daily prescribed medication, they can take this medication with a small amount of food.
- ACTH Stimulation Testing: This test is typically performed to monitor patients after starting treatment for Cushing’s disease. Fasting helps prevent lipemic blood and allows proper interpretation of cortisol levels. HOWEVER, patients must take their morning dose of Vetoryl with a small amount of food 4 to 6 hours before the test.
- Pancreatic Function Tests: Measurement of substances such as canine pancreatic lipase (cPL) and feline pancreatic lipase (fPL) are sensitive to food intake and hence require fasting.
- Abdominal Ultrasound: An empty stomach allows better imaging of the abdominal organs. This is particularly relevant when scanning the intestinal tract, gall bladder, stomach, small intestinal tract, and pancreas.
- Abdominal X-Rays (Radiographs): An empty stomach allows better imaging of the abdominal organs - especially the stomach and small intestinal tract.
Fasting NOT NEEDED for test Tests:
- Blood Glucose Curve: Patients need to eat a normal amount of food before they receive their morning insulin injection (always done at home before the glucose curve at the hospital).
- Chest Xrays (Radiographs)
- Echocardiogram
- EKG
- CBC
It's important to remember these guidelines apply to most routine cases. However, they might not be suitable for all animals, especially those with certain health conditions like diabetes, kittens, puppies, or very small breeds that might be prone to hypoglycemia. If in doubt, please consult with the supervising veterinarian.
Also, always ensure to communicate clearly with our clients about the need for their pet to fast, the duration of fasting, and when they should resume feeding after the test.