The Importance of Pre-Surgical Bloodwork

Why Should I Do Pre-Surgical Bloodwork?

Based upon an article by Fred Metzger, DVM, Dipl. ABVP

1. Renal failure can occur in young pets. Geriatric pets are prone to renal disease, which can adversely affect anesthesia. But what about young animals? An investigation revealed that the cocker spaniel, Norwegian elkhound, Doberman pinscher, Lhasa apso, Shih Tzu, Samoyed, standard poodle, soft-coated wheaten terrier, and bull terrier are predisposed to familial renal disease. The onset of renal failure varied from age 2 months to 5 years. Some patients showed no abnormalities, but others showed lethargy, vomiting, polyuria and polydipsia. Young cats also may develop renal disease. This research makes a strong argument for screening young cats and dogs undergoing such routine surgeries as castration, ovariohysterectomy, and declawing.

2. Hypoglycemia can complicate anesthesia, surgery, and recovery. Poor glucose reserves and reduced gluconogenic abilities predispose a young pet to hypoglycemia, particularly when fasted before anesthesia or surgery. Toy breeds, such as Yorkshire terriers, are susceptible to juvenile hypoglycemia. Other conditions causing hypoglycemia in young pets include portosystemic shunts, sepsis, and hyperadrenocorticism. Hypoglycemia at any age can make anesthesia risky.

3. Dehydration can cause serious complications. Hypotension, coupled with anesthetics and blood loss, may result in postoperative hypoperfusion and renal failure. Fluid administration isn’t mandatory for surgery in healthy animals, but is recommended for dehydrated patients. Hydration can be evaluated for by using such physical exam findings, such as skin turgor and mucus membrane moistness. However, such routine laboratory tests as total protein, hematocrit, and urine specific gravity provide more detailed information.

4. Liver disease can occur in young pets. Hepatic diseases can occur in pets 6 months to 1 year old. Portosystemic shunts, hepatic cysts, biliary atresia, and gall bladder anomalies are reported in most cat breeds, including Persians, Himalayans, Siamese, and domestic shorthairs and longhairs. Portosystemic shunts occur most frequently in dogs and cats younger than 1 year. The Yorkshire terrier, miniature schnauzer, Irish wolfhound, and mixed-breed dogs have the highest liver disease incidence. Anesthesia is avoided in pets suspected of having portosystemic shunts.

5. Many anesthetic agents shouldn’t be used in patients with liver or kidney disease. Several common anesthetic and sedative agents shouldn’t be used when liver or kidney disease is present. These agents may induce renal or hepatic failure in a compromised patient. Pre-anesthetic screens include tests that shed light on hepatic and renal functions.

6. If you or I would be scheduled for surgery, our doctor would perform pre-anesthetic tests to make sure we are as healthy as we can be before the procedure. This helps put patients in a low-risk area. Why should we do anything less for our pets?

7. We can establish normal baseline values at an early age. Patient values vary, so we follow trends in test parameters to determine the significance of abnormal results. We can compare future test results with the baselines established during pre-anesthetic testing. This helps us to monitor your pet’s health. When we detect a problem early, we can treat the disease before it becomes serious. In essence, pre-anesthetic testing serves as a wellness profile.

8. Pre-anesthetic testing will detect abnormalities. Think about “when” and not “if” pre-anesthetic testing will pay off. The results will benefit everyone—it boosts your confidence in us and it helps us to keep your pet healthy.