Aspectos ultrassonográficos abdominais em camundongos hígidos

Abstract

Mice (Mus musculus) are rodents widely used as experimental models in research due to their short lifespan, small size, ease of handling and reproduction, and anatomical and genetic similarities to humans. Despite their frequent use in science and also as pets, there is a lack of data in the literature regarding abdominal ultrasonography in this species. This study aimed to describe the qualitative and quantitative abdominal ultrasonographic features of healthy mice. Twenty animals (10 males and 10 females), aged between 5 and 12 months and weighing 25 to 36 g, were selected from the certified animal facility of UFFS, Realeza campus. Chemical restraint was performed using midazolam (5 mg/kg, IM) in the quadriceps femoris muscle, combined with physical restraint via dorsal skinfold. Trichotomy was performed from the xiphoid to the pubic region, followed by complete abdominal ultrasonographic evaluation using a commercially available portable ultrasound system with a multifrequency linear transducer (8–17 MHz). Parameters such as organ positioning, morphology, margin definition, echogenicity, echotexture, vascularization, anatomical relationships, wall layering, number of peristaltic contractions in 15 seconds, and echogenicity of biliary, urinary, and gastrointestinal contents were recorded. Quantitative measurements (in millimeters) included adrenal gland length and thickness (cranial and caudal poles), kidney length and width, ovarian and testicular dimensions, uterine horn and body thickness, seminal gland thickness, and wall thickness of the stomach, small and large intestines, spleen, urinary bladder, and pancreas. Images were acquired in longitudinal and transverse planes; for kidneys, a dorsal plane was also included. After ultrasonographic evaluation, animals were euthanized with an isoflurane overdose in a customized inhalation chamber. Four specimens (two males and two females) had their thoracic and abdominal cavities filled with 10% formaldehyde and were submerged in formalin for 48 hours. Organ measurements were then performed using a digital caliper, following the same ultrasonographic parameters. Additional specimens were fixed in 10% formalin for anatomical sectioning and photographic documentation. Comparisons between sexes and between ultrasonographic and anatomical data were conducted using statistical tests in GraphPad Prism® 8.0.2. Ultrasonographic measurements were consistent with anatomical findings, with no statistically significant differences between methods or sexes. The results provide a reference atlas of mouse abdominal ultrasonography, which may support veterinary sonographers, clinicians, and researchers in experimental and diagnostic applications.