Direct intra-abdominal pressures and abdominal perfusion pressures in unsedated normal horses.

Objectives: To determine whether direct intra-abdominal pressures (IAP) and calculated direct abdominal perfusion pressures (APP) are location dependent within the abdomen of standing horses. We hypothesize that IAP will be increased and calculated APP will be decreased at a ventral abdominal location (V) when compared to values obtained from the left (LFl) or right flank (RFl).

Design: Prospective experimental design.

Setting: University-based equine research facility.

Animals: Seven healthy adult horses, 4 geldings and 3 mares.

Interventions: Measurements of direct IAP obtained from the RFl, LFl, and V locations via abdominal cannulation and direct arterial blood pressures obtained via catheterization of the transverse facial artery were obtained in fasted, standing, unsedated horses. APP was calculated for each location by the subtraction of IAP from the mean arterial pressure. Differences between sites of measurement for IAP, APP, and their gradients were calculated and compared by ANOVA and t-tests.

Measurements And Main Results: Mean flank IAP measurements were subatmospheric and negative compared to ventral IAP values (LFl = -3 mm Hg, RFl = -5 mm Hg, V = 25 mm Hg; P < 0.001 between each flank and the ventral location). Ventrum APP was lower than flank APP (V = 82 mm Hg; LFl = 106 mm Hg; RFl = 108 mm Hg; P = 0.029 between each flank and the ventral location). Gradient calculations between sites showed the IAP increased and APP decreased from dorsal to ventral (P < 0.05) and from right to left (P = 0.004) within the abdomen.

Conclusions: IAP and calculated APP are location dependent. These data provide new information regarding abdominal pressure profiles in standing healthy adult horses.