Effect of Intravenous or Perivascular Injection of Synthetic Adrenocorticotropic Hormone on Stimulation Test Results...

Standard protocols for adrenocorticotropic hormone (ACTH) stimulation testing (ACTHst) often involve intravenous (IV) injection of corticotropin. ACTH might be unintentionally injected into the perivascular (PV) space.

To compare stimulation test results after IV and PV injections of ACTH.

Twenty privately owned dogs were studied: 10 healthy and 10 with trilostane-treated naturally occurring hyperadrenocorticism (HAC).

Prospective study. Each of 20 dogs underwent 2 ACTHst not <4 nor more than 14 days apart. Five healthy and 5 HAC dogs had an IV ACTHst first and PV second; 5 healthy and 5 HAC dogs had a PV ACTHst first and IV second. Blood samples for measurement of serum cortisol concentration were collected before and 1 hour after ACTH administration.

No significant difference in results was demonstrated when comparing serum cortisol concentrations after IV and PV ACTH administration in all 20 dogs (median μg/dL; interval μg/dL: 8.2; 1.4-17.4 versus 7.8; 0.9-16.9; P = .23). No significant difference in results was demonstrated when comparing serum cortisol concentrations after IV and PV ACTH administration in the 10 healthy dogs (median μg/dL; interval μg/dL: 10.9; 7.3-17.4 versus 10.6; 7.1-16.9; P = .54) or in the 10 HAC dogs (median μg/dL; interval μg/dL: 6.3; 1.4-8.6 versus 5.2; 0.9-8.7; P = .061).

Perivascular administration of ACTH does not significantly alter stimulation test results in healthy dogs or in dogs with HAC undergoing therapy with trilostane.