Abstract The aim of this study was to measure the nuchal translucency (NT) of canine fetuses to establish reference values for healthy gestational processes and to verify its effectiveness in the diagnosis of congenital abnormalities. On day 34 of gestation, the NT of three fetuses from each of the 26 English bulldog female dogs was measured. The first fetus was the one located immediately cranial to the bladder, the second was selected from the left side of the abdomen, and the third from the right side. The reference values for healthy animals were offset using descriptive statistics. The diagnostic ability of the test to identify fetal malformations was studied using receiver operating characteristic curve analysis. Of the 26 litters, only 18 had healthy fetuses, 4 had fetuses with anasarca, 3 had fetuses with abdominal wall defects, and 1 had both types of abnormalities. The NT was higher in canine fetuses that presented anasarca in the litter than in normal litters (1.8 ± 0.77 mm vs. 1.4 ± 0.48 mm; P = 0.0249), with a cut-off value of NT > 1.45 mm (sensitivity = 61.54%, specificity = 70.18%). NT greater than 1.45 mm seems to be a diagnostic tool for the identification of anasarca during gestation of bulldogs. Considering the unprecedented use of this parameter in canine species and the limitations found during the study, further studies will be needed in order to use it on clinical practice.

RESUMO: O objetivo do presente estudo foi obter valores ecobiométricos para os tecidos materno-fetais caninos, usando a ultrassonografia de alta definição (HDUS), desenvolvendo fórmulas para prever a idade gestacional das cadelas. Doze cadelas saudáveis de raças braquicefálicas pesando 7-13kg e com idades entre um e quatro anos foram incluídas. Os fetos foram analisados diariamente com ultrassonografia convencional e de alta definição, do oitavo dia após a inseminação artificial até o dia do parto, utilizando o equipamento de ultrassom ACUSON S2000/SIEMENS e software específico. Estruturas embrionárias e fetais; diâmetro da vesícula embrionária; comprimento do embrião; diâmetro biparietal, comprimento abdominal e altura renal; comprimento do fêmur, úmero, escápula, rádio e tíbia; espessamento da parede do estômago; comprimento adrenal; e tamanho cardíaco foram medidos. Essas variáveis foram correlacionadas com o teste gestacional e ajustado de acordo com os modelos de regressão. Os resultados obtidos (P<0,001) para: diâmetro lateral do saco gestacional (R2=81,8%); comprimento do embrião (R2=85,7%); diâmetro biparietal (R2=99,1%) e abdominal (R2=97,2%); espessura da parede gástrica (R2=86,9%); comprimento do fêmur (R2=96,6%), rádio (R2=97,5%), úmero (R2=96,5%), escápula (R2=95,8%) e tíbia (R2=97,3%); comprimento do rim (R2=95,8%) e altura (R2=96,0%); comprimento adrenal (R2=89,6%); o comprimento do coração (R2=93,0%) e a altura (R2=91,5%) dos fetos caninos apresentaram correlação significativa com os dias gestacionais. Isso permitiu monitorar o crescimento fetal e estimar a idade com alta precisão em diferentes períodos gestacionais.

ABSTRACT: The objective of the present study was to obtain echobiometric values for the most important canine maternal-fetal tissues using high-definition ultrasonography (HDUS) trying to update the formulas for predicting gestational age. Twelve healthy bitches of brachycephalic breeds weighing 7-13kg and aged one to four years were included. The fetuses were analyzed every day using conventional and high-definition ultrasonography from the eighth day after artificial insemination until the day of delivery, using the ACUSON S2000/SIEMENS ultrasound equipment and specific software. Embryonic and fetal structures; diameter of the embryonic vesicle; length of the embryo; biparietal diameter, abdominal length and kidney height; length of the femur, humerus, scapula, radius, and tibia; thickening of the stomach wall; adrenal length; and cardiac size were measured. These variables were correlated with gestational and adjusted tested according to regression models. The results obtained (P<0.001) for: lateral diameter of the gestational sac (R2=81.8%); length of the embryo (R2=85.7%); biparietal (R2=99.1%) and abdominal diameter (R2=97.2%); thickness of the gastric wall (R2=86.9%); length of the femur (R2=96.6%), radius (R2=97.5%), humerus (R2=96.5%), scapula (R2=95.8%) and tibia (R2=97.3%); kidney length (R2=95.8%) and height (R2=96.0%); adrenal length (R2=89.6%); heart length (R2=93.0%) and height (R2=91.5%) of the canine fetuses showed significant correlation with gestational days. This allowed monitoring fetal growth and estimation of age with high accuracy in different gestational periods.