Before this valuable fluid can be analyzed, it must first be collected. In most cases, venous blood is used for testing, while arterial blood provides different information for specific conditions. As a general rule, veterinary technicians—similar to nurses—perform the blood draw.

Several veins may be used for collection. The most commonly accessed are the jugular veins (on either side of the neck), the lateral saphenous veins (on the hind legs), and the cephalic veins (on the front legs). If only a small sample is required, peripheral veins may be used; however, collecting from the jugular vein is often preferred to minimize artifacts such as early clotting of the sample. Rest assured, the risks associated with these collection sites are minimal, and every effort is made to ensure your pet remains as comfortable as possible during the procedure.

There is often some confusion surrounding the term “blood test,” as it refers both to the collection technique and to the laboratory analysis itself. It’s also important to understand that a single blood test does not evaluate everything. For example, heartworm screening does not measure blood components directly, but rather detects specific markers related to the parasite.

Depending on the reason bloodwork is needed, your veterinary team will recommend one panel over another. The number of variables that can be measured from a blood sample is extensive. To simplify interpretation, certain tests are grouped into specific “panels” based on what needs to be evaluated for the individual patient. With hundreds of possible tests and combinations available, your veterinary team will recommend the most appropriate option for your pet.

Depending on the parameters being measured, some tests require your pet to fast beforehand or to have the sample collected at a specific time of day to ensure accurate results. Other analyses may require multiple samples to assess changes throughout the day or to monitor response to treatment over time.

Additionally, some test results are available quickly and can be performed directly at the veterinary hospital, while others must be sent to an external laboratory. As a result, turnaround times may range from a few days to several weeks.

Although many blood tests exist—including those used to screen for parasites such as heartworm—certain panels are more commonly performed. Generally, when your veterinarian recommends bloodwork, they are referring to a complete blood count (CBC) and a chemistry profile.

Hematology (Complete Blood Count)

This analysis provides important information about the cells circulating in the blood. A complete blood count evaluates red blood cells, white blood cells, and platelets, measuring their numbers, proportions relative to one another, average size, and morphology.

Hematology includes automated laboratory analysis as well as a microscopic examination of a blood smear performed by a veterinary technician.

In summary, red blood cells transport oxygen throughout the body, along with certain proteins, hormones, and other molecules. White blood cells are primarily involved in the immune system and play a key role in defending the body against infections. Platelets are essential for blood clotting and, along with other clotting factors, help control bleeding.

Chemistry Profile

This portion of the analysis measures the levels of various chemical substances in the blood, such as enzymes, electrolytes, lipids, hormones, glucose (sugar), proteins, vitamins, and minerals.

Abnormal levels of these components may indicate dysfunction in a related organ. For example, certain parameters are associated with liver function (e.g., AST, ALP, GGT), while others provide information about kidney function (e.g., blood urea nitrogen [BUN], creatinine). Interpreting these values helps the veterinarian assess how well the organs responsible for producing, processing, or eliminating these substances are functioning.

D’autres tests sanguins peuvent complémenter un bilan sanguin tel que la T4 (Thyroxine) et la TSH (Thyréotropine) qui évaluent la fonction thyroïdienne. Outre les tests sanguins pour connaître le statut des organes de l’animal, il existe également une multitude de tests sanguins encore plus spécifiques qui peuvent être proposés pour détecter certaines maladies. Les possibilités sont infinies, et ce, avec quelques millilitres de sang seulement.

Using sophisticated equipment, blood test results are compiled into a report and made available to your veterinarian. Values that fall outside the normal range are clearly flagged, but it is your veterinarian who determines whether they are clinically significant.

The results must be analyzed and interpreted in the context of the clinical information gathered during the consultation (medical history, physical examination, and any additional tests performed). Your veterinarian will then discuss their conclusions with you—whether that involves a diagnosis and treatment plan or the recommendation for further testing.

Bloodwork may be recommended if your pet shows changes in overall health or behavior. A pet that suddenly becomes restless, lethargic, experiences vomiting, diarrhea, or any other symptoms will often benefit from blood testing as a primary diagnostic tool to help identify the problem or rule out certain conditions.

In addition, annual preventive blood testing is an excellent practice to help monitor your pet’s health and detect potential issues early. Keep in mind that one year in the life of a dog or cat represents several “human years,” and many medical conditions can develop over time. As pets age, routine blood panels become increasingly important.

If you have any questions or concerns, your veterinary team can guide you toward the best decisions for your companion.