Mensuration of the rabbit pituitary gland from computed tomography

Abstract

The aim of this retrospective reference interval observational study was to determine the mensuration of the pituitary gland (hypophysis cerebri) by analyzing CT studies in rabbits without clinical evidence of pituitary disease or central neurologic signs. Though diseases of the rabbit pituitary gland are uncommon, the pituitary gland is essential in regulation of the rabbit's endocrine system, as in other species. Currently, there are minimal published studies that detail the rabbit head anatomy on cross-sectional imaging, and even less specifically examining the pituitary gland. The pituitary gland was measured by one observer at a single time point from transverse and reconstructed sagittal CT images in a soft-tissue algorithm in 62 rabbits for a total of 66 rabbit head CT studies. The rabbits ranged from 0.84 to 14 years in age (mean ± SD: 5.46 ± 3.05 years) and 0.92 to 4.95 kg in weight (2.21 ± 0.83 kg). Linear pituitary measurements were performed using electronic calipers. The mean ± SD pituitary height was 4.22 ± 0.57 mm, width was 4.48 ± 0.71 mm, and length was 6.02 ± 0.70 mm. The pituitary gland height-to-brain area ratio was 1.10 ± 0.16 mm −1 , which is much higher than the values reported in normal dogs and cats. The age, weight, and sex of the rabbits were not found to have a significant impact on pituitary gland mensuration. These measurements could be useful as a reference range for future rabbit head CT studies and to rule out pituitary enlargement or disease when evaluating rabbit pituitary glands. K E Y W O R D S

Examination of the Topography and Morphometry of Hypophysis (Glandula pituitaria) by Computed Tomography in New Zealand Rabbits

“…In the study, mean height and width values of the hypophysis of New Zealand Rabbit were found as 2.78 ± 0.31 mm and 2.13 ± 0.23 mm, respectively. In their study, Kwan et al (14), found the height of the gland as 4.22 ± 0.57 mm and its width as 4.48 ± 0.71 mm in the measurements taken from the CT images of the rabbits, while Müllhaupt et al (20), examined the height and width of hypophysis of New Zealand rabbit by using MRI and found them as 3.5 ± 0.26 mm and 3.5 ± 0.59 mm, respectively. It is thought that such differences between morphometric data may be caused by the variation in population sizes and the differences in the principle and modality of the imaging systems.…”

“…It is important to determine the detailed characteristics of hypophysis due to the presence of surrounding vital structures and its anatomic location. There are various studies about hypophysis via advanced imaging techniques (14)(15)(16)(17)(18)(19). However, in the literature, no study was found in which the topography of the gland was detected in cavum cranii.…”

Sonography of the pituitary gland in pet rats

“…1,11 As in rabbits and humans, a prolactin-producing pituitary adenoma induces diffuse mammary hyperplasia and dysplasia and may lead to cystic mammary adenocarcinoma. 12 Ovariectomized Sprague-Dawley 90-day-old rats had a significantly lower incidence of mammary tumors (4%) than intact rats (47%), and also a significantly lower incidence of pituitary adenomas (4% vs. 66%). 13 Most pituitary tumors compress brain tissue, leading to clinical signs typical of central vestibular diseases, such as head tilt, ataxia, proprioceptive deficits with normal muscle strength, wide-based stance, knuckling, and an abnormal gait, depression or hydrocephalus, seizures, and paresis.…”

“…Mammary tumors tend to be prolactin‐responsive and may develop in the presence of a functional pituitary adenoma 1,11 . As in rabbits and humans, a prolactin‐producing pituitary adenoma induces diffuse mammary hyperplasia and dysplasia and may lead to cystic mammary adenocarcinoma 12 . Ovariectomized Sprague–Dawley 90‐day‐old rats had a significantly lower incidence of mammary tumors (4%) than intact rats (47%), and also a significantly lower incidence of pituitary adenomas (4% vs. 66%) 13…”

Computed tomographic features of the normal spleen in rabbits (Oryctolagus cuniculus domesticus)

“…Being a prey species, rabbits often hide signs of disease and therefore the initial clinical examination can be limited in diagnostic accuracy. Computed tomography has been developed as an excellent diagnostic tool for rabbits, allowing the diagnosis of many conditions such as dental disease, otitis, pituitary neoplasia, liver lobe torsion, and sacculitis 1–5 . CT examination of rabbits can be performed without sedation in a designated restraining device (VetCatTrap™), and with the administration of intravenous contrast medium via a catheter in the marginal ear vein 6 .…”