Page 879 - Small Animal Internal Medicine, 6th Edition

CHAPTER 49 Disorders of the Endocrine Pancreas 851

The IV dextrose infusion can be initiated the evening before of fluid therapy during the perioperative period. Severe pan-
surgery, at the time food and water are withheld and con- creatitis occurs most commonly with attempts to remove
VetBooks.ir tinued throughout the perioperative period. Initiating fluid tumors located in the body of the pancreas, where the blood
supply and the pancreatic ducts are located. Tumors located
therapy before surgery helps ensure adequate circulation to
the pancreas thereby minimizing the risk of postoperative
because of the high prevalence of postoperative life-
pancreatitis. in the body of the pancreas should be considered inoperable
Concentrations of dextrose in excess of 5% should be threatening pancreatitis despite appropriate perioperative
avoided to prevent overstimulation of the pancreatic tumor treatment aimed at preventing its development. The reader
and rebound hypoglycemia. If the dextrose infusion is inef- is referred to Chapter 37 for information on the treatment
fective in preventing severe hypoglycemia, a constant-rate of pancreatitis.
infusion of glucagon should be considered. Glucagon is a The development of transient diabetes mellitus after sur-
potent stimulant of hepatic glycogenolysis and gluconeogen- gical removal of a β-cell tumor is not an indication of cure.
esis and is effective in maintaining normal blood glucose It is believed to result from inadequate insulin secretion by
concentrations in dogs with β-cell neoplasia when adminis- “atrophied” normal β cells. Removal of all, or most, of the
tered by constant rate infusion (Fig. 49.20). Lyophilized glu- neoplastic cells acutely deprives the dog of insulin. Until the
cagon USP (1 mg) is reconstituted with the diluent provided atrophied normal cells regain their secretory abilities, the
by the manufacturer (Eli Lilly), and the solution is added to dog will be hypoinsulinemic and may require exogenous
1 L of 0.9% saline, making a 1-µg/mL solution that can be insulin injections to maintain euglycemia. Insulin therapy is
administered by syringe pump. The initial dose is 5 to 10 ng/ initiated postoperatively only if hyperglycemia and glycos-
kg of body weight/min. The dose is adjusted, as needed, to uria persist for longer than 1 to 2 days beyond the time that
maintain blood glucose concentration between 60 and all dextrose-containing IV fluids have been discontinued.
100 mg/dL. When glucagon is discontinued, the dose should Initial insulin therapy should be conservative, that is, 0.25 U
be gradually decreased over 1 to 2 days and the blood glucose of lente or NPH insulin per kilogram of body weight should
concentration monitored for recurrence of hypoglycemia. be given once daily. Subsequent adjustments in insulin
dosage or frequency of administration should be made
POSTOPERATIVE COMPLICATIONS according to clinical response and blood glucose determina-
The most common postoperative complications are pancre- tions. The need for insulin treatment is usually transient,
atitis, hyperglycemia, and hypoglycemia. The development lasting from a few days to a few months. Rarely will a dog
of these complications is directly related to the expertise of remain diabetic for longer than 6 months. Client evaluation
the surgeon in handling pancreas and excising these tumors,
the location of the tumor in the pancreas (i.e., peripheral
limb versus body of the pancreas; Fig. 49.21), the presence
or absence of functional metastatic lesions, and the adequacy

Blood glucose (mg/dL)
150 14
Glucagon stopped
Stomach
100 Sx Glucagon
tapered
50
Glucagon infusion
0
1 3 5 7 9 37
Days 36
Pancreas
FIG 49.20
Blood glucose concentrations in a 13-year-old female
spayed Pomeranian before and after surgical removal of an
insulin-secreting β-cell tumor. Pancreatitis and severe
hypoglycemia developed postoperatively. The hypoglycemia
resolved and euglycemia was maintained after the initiation
of a constant-rate intravenous (IV) infusion of glucagon. The Duodenum
dosage of glucagon was gradually tapered beginning on
day 5, feeding of small amounts of food was begun on day
7, and the IV infusion of glucagon was stopped on day 8. FIG 49.21
Severe hypoglycemia did not recur. Sx, surgery (From Tumor location in 87 dogs with islet β-cell tumors. (Adapted
Feldman EC et al: Canine and feline endocrinology, ed 4, from Feldman EC et al: Canine and feline endocrinology
St Louis, 2015, Elsevier Saunders.) and reproduction, ed 3, St Louis, 2004, WB Saunders.)