Sonographic features of drug‐induced splenic congestion

Abstract

Drug-induced splenic congestion has been reported in dogs secondary to barbiturate administration. This research attempted to verify and quantify size changes associated with drug-induced splenic congestion in dogs. Transverse plane ultrasound images of the spleen in normal dogs were collected to determine the maximum diameter in the minimum dimension prior to, and 15 min after, administration of acepromazine, thiopental, or propofol. Significant splenic enlargement was seen after administration of acepromazine (P<0.01) and thiopental (P=0.02), but no enlargement was seen after administration of propofol. Significantly increased attenuation (P<0.01) and a trend of increased backscatter (P=0.09) were measured after administration of acepromazine. These results indicate that measurable splenomegaly occurs after acepromazine and thiopental administration. This represents the first report of a condition causing measurable diffuse increased attenuation in the spleen. Propofol does not cause measurable splenic enlargement under the conditions of this research.

Congestão esplênica associada a aplicação de acepromazina em cães

“…Th e data obtained in the study confirm those described by O'Brien, Waller and Osgood (2004), who described splenic dilation after acepromazine administration. Disagreeing with these authors, Baldo et al (2012) found no difference in spleen volume by computed tomography after acepromazine use (0.03 mg/kg).…”

“…This sequestration can be detrimental to some animals (WILSON; EVANS; CARPENTER, 2004), especially those that are hematological impaired prior to surgery. Mechanism of splenomegaly associated with the acepromazine administration is not known but may be related to the α1-adrenergic blockade leading to smooth muscle relaxation and vasodilatation with consequent passive congestion; these changes allow stretching of the spleen capsule's smooth muscle fibers, with enlargement and the increased number of cells (LANG;EGLEN;HENRY, 1979;O´BRIEN;WALLER;OSGOOD, 2004;PARRY;ANDERSON, 1983;WILSON;EVANS;CARPENTER, 2004).…”

“…Splenomegaly is associated with many causes, including the administration of phenothiazine tranquilizers, which are extensively used in veterinary medicine (O'BRIEN;WALLER;OSGOOD, 2004). Among the phenothiazines, acepromazine is frequently used to tranquilize animals (LEMKE, 2007), it is relatively safe (HALL;CLARKE, 1987) and is low in cost.…”

Radiografia quantitativa hepática de cães tranquilizados com acepromazina

“…Entretanto, esses fármacos não são seletivos para os receptores dopaminérgicos, interagindo também com receptores alfa-1 adrenérgicos periféricos. O bloqueio de receptores alfa-1 adrenérgicos vasculares resulta em vasodilatação periférica, redução na pressão arterial (MONTEIRO et al, 2007) e aumento da perfusão cutânea (BROCK, 1994) e visceral (O'BRIEN et al, 2004). Foi demonstrado também que a acepromazina reduz o hematócrito em cães, sugerindo o sequestro de células vermelhas no baço com consequente esplenomegalia (LANG et al, 1979;O'BRIEN et al, 2004;MONTEIRO et al, 2007).…”

“…O bloqueio de receptores alfa-1 adrenérgicos vasculares resulta em vasodilatação periférica, redução na pressão arterial (MONTEIRO et al, 2007) e aumento da perfusão cutânea (BROCK, 1994) e visceral (O'BRIEN et al, 2004). Foi demonstrado também que a acepromazina reduz o hematócrito em cães, sugerindo o sequestro de células vermelhas no baço com consequente esplenomegalia (LANG et al, 1979;O'BRIEN et al, 2004;MONTEIRO et al, 2007). Por outro lado, existe pelo menos um estudo na literatura que relata a inexistência de correlação entre as alterações no hematócrito promovidas por agentes anestésicos (incluindo a acepromazina) e o volume do baço (WILSON et al, 2004), sugerindo o sequestro de células vermelhas em outros locais além do baço.…”