Adrenal response to adrenocorticotropic hormone in dogs before and after surgical attenuation of a single congenital portosystemic shunt.
BACKGROUND
Dogs with single congenital portosystemic shunts (CPSS) often develop postoperative hypoglycemia and prolonged anesthetic recovery. These abnormalities could be attributable to inadequate adrenal response. However, adequacy of adrenal response after CPSS surgery is unexplored.


OBJECTIVE
Dogs with CPSS have inadequate postoperative adrenal response.


METHODS
Eight nonoperated, 8 ovariohysterectomy (OHE), and 16 CPSS dogs.


METHODS
Consecutive day ACTH stimulation tests were performed on nonoperated healthy dogs, healthy dogs before and after OHE, and CPSS dogs before and after surgery. Adequate response was defined as >50% or >30 ng/mL increase in cortisol after ACTH administration. Blood glucose (BG) was monitored before and after surgery. Prolonged anesthetic recovery and refractory hypoglycemia episodes were recorded.


RESULTS
Results of consecutive day ACTH stimulation tests did not vary in normal dogs. Results of preoperative ACTH stimulation tests of CPSS and OHE dogs were not significantly different. Dogs with CPSS had higher postoperative baseline cortisol concentrations (median, 329 ng/mL) than OHE dogs (median, 153 ng/mL). Postoperative cortisol increase after ACTH in CPSS was < or =50% in 10/16 and < or =30 ng/mL in 6/16. After surgery, BG was < or =60 mg/dL in 7/16 CPSS dogs. Cortisol concentrations were not correlated with BG. Two CPSS dogs had refractory hypoglycemia and 4 had delayed recovery; all improved with dexamethasone administration (0.1-0.2 mg/kg/IV).


CONCLUSIONS
Contrary to previous reports, baseline cortisol concentrations in CPSS and healthy dogs are similar. Many CPSS dogs have postoperative hypercortisolemia. Response to ACTH does not correlate with postoperative hypoglycemia or prolonged anesthetic recovery.
Holford
A L
AL
Department of Small Animal Clinical Science, University of Tennessee Veterinary Teaching Hospital, Knoxville, TN 37996, USA. aholford@utk.edu
Tobias
K M
KM
Bartges
J W
JW
Johnson
B M
BM
D000311:Adrenal Glands / Q000187:drug effects* / Q000502:physiology; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D000818:Animals; D000013:Congenital Abnormalities; D004283:Dog Diseases / Q000378:metabolism / Q000601:surgery*; D004285:Dogs; D005260:Female; D008297:Male; D011168:Portal System / Q000002:abnormalities* / Q000601:surgery
D000324:Adrenocorticotropic Hormone