Objective—To evaluate the effects of exogenous
insulin on clearance of exogenous glucose in alpacas.
Animals—7 adult castrated male alpacas.
Procedure—Prior to each of 2 trials, food was withheld
for 8 hours. Glucose (0.5 g/kg of body weight)
was then administered by rapid IV infusion. During 1
of the trials, regular insulin (0.2 U/kg, IV) was also
administered 15 minutes later. Blood was collected
immediately before (0 minutes) and 15, 20, 25, 30,
45, 60, 90, 120, 180, and 240 minutes after glucose
administration. Plasma concentrations of glucose and
lactate were determined, and glucose fractional
turnover rate and plasma half-life were calculated.
Results—Insulin treatment caused a significant
increase in fractional turnover rate of glucose and
plasma lactate concentration. Plasma glucose concentrations
were less in insulin-treated alpacas from
30 minutes after glucose administration (15 minutes
after insulin administration) until the conclusion of
each trial, compared with nontreated alpacas. In addition,
plasma glucose concentration in insulin-treated
alpacas returned to baseline values 1 hour sooner
than in the nontreated group.
Conclusion and Clinical Relevance—Glucose
uptake in alpacas improves after insulin treatment,
suggesting that administration of exogenous insulin
will increase the therapeutic and decrease the pathologic
effects of exogenous glucose administered to
hypoglycemic alpacas. However, alpacas and other
New World camelids should be monitored carefully
during treatment with glucose or insulin, because
these species appear to be partially insulin resistant.
(Am J Vet Res 2001;62:1544–1547)
Objective—To evaluate effects of hydrocortisone
administration, with and without concurrent administration
of insulin, on intermediary metabolism in
Animals—8 adult castrated male alpacas.
Procedure—On each of 2 consecutive days, food
was withheld from alpacas for 8 hours. Alpacas then
were administered 1 mg of hydrocortisone sodium
succinate/kg, IV (time 0). On 1 of the days, randomly
assigned alpacas were also administered regular
insulin (0.2 U/kg, IV) 120 minutes after hydrocortisone
administration. Blood samples were collected at 0,
120, 135, 150, 165, 180, 210, 240, 300, and 360 minutes.
Plasma concentrations of glucose and lactate
and serum concentrations of triglycerides, cholesterol,
nonesterified fatty acids, and β-hydroxybutyrate
were determined. Data were compared between
days. Additionally, serum insulin concentrations
before and after hydrocortisone administration were
determined for selected samples.
Results—Hydrocortisone administration induced
hyperglycemia, hyperinsulinemia, a reduction in concentrations
of triglycerides and cholesterol, and a
reduction in triglyceride-to-cholesterol ratio. Subsequent
insulin administration temporarily negated
the hyperglycemic effects of hydrocortisone, induced
temporary hyperlactemia, and augmented the reduction
in blood triglycerides.
Conclusion and Clinical Relevance—A single dose
of a short-acting corticosteroid does not increase
blood lipid fractions in healthy alpacas, probably
because of a competent endogenous insulin
response. Corticosteroids may induce differing
responses in camelids with depleted glycogen stores
or an ineffective insulin response. Administration of
insulin can effectively negate the hyperglycemic
effects of hydrocortisone and augment lipoprotein
clearance. Hence, insulin administration may be therapeutic
for alpacas with hyperglycemia, hyperlipemia,
or hyperketonemia. (Am J Vet Res 2002;63:1269–1274)