Renal scintigraphy in veterinary medicine.

Renal scintigraphy is performed commonly in dogs and cats and has been used in a variety of other species. In a 2012 survey of the members of the Society of Veterinary Nuclear Medicine, 95% of the respondents indicated they perform renal scintigraphy in their practice. Renal scintigraphy is primarily used to assess renal function and to evaluate postrenal obstruction. This article reviews how renal scintigraphy is used in veterinary medicine and describes the methods of analysis. Species variation is also discussed.

Estimation of feline renal volume using computed tomography and ultrasound.

Renal volume estimation is an important parameter for clinical evaluation of kidneys and research applications. A time efficient, repeatable, and accurate method for volume estimation is required. The purpose of this study was to describe the accuracy of ultrasound and computed tomography (CT) for estimating feline renal volume. Standardized ultrasound and CT scans were acquired for kidneys of 12 cadaver cats, in situ. Ultrasound and CT multiplanar reconstructions were used to record renal length measurements that were then used to calculate volume using the prolate ellipsoid formula for volume estimation. In addition, CT studies were reconstructed at 1 mm, 5 mm, and 1 cm, and transferred to a workstation where the renal volume was calculated using the voxel count method (hand drawn regions of interest). The reference standard kidney volume was then determined ex vivo using water displacement with the Archimedes' principle. Ultrasound measurement of renal length accounted for approximately 87% of the variability in renal volume for the study population. The prolate ellipsoid formula exhibited proportional bias and underestimated renal volume by a median of 18.9%. Computed tomography volume estimates using the voxel count method with hand-traced regions of interest provided the most accurate results, with increasing accuracy for smaller voxel sizes in grossly normal kidneys (-10.1 to 0.6%). Findings from this study supported the use of CT and the voxel count method for estimating feline renal volume in future clinical and research studies.

Determination of testicular blood flow in camelids using vascular casting and color pulsed-wave Doppler ultrasonography.

We describe the vasculature of the camelid testis using plastic casting. We also use color pulsed-wave Doppler ultrasonography to measure testicular blood flow and compare the differences between testicular blood flow in fertile and infertile camelids. The testicular artery originates from the ventral surface of the aorta, gives rise to an epididymal branch, and becomes very tortuous as it approaches the testis. Within the supratesticular arteries, peak systolic velocity (PSV) was higher in fertile males compared to infertile males (P = 0.0004). In addition, end diastolic velocity (EDV) within the supratesticular arteries was higher for fertile males when compared to infertile males (P = 0.0325). Within the marginal arteries, PSV was also higher in fertile males compared to infertile males (P = 0.0104). However, EDV within the marginal arteries was not significantly different between fertile and infertile males (P = 0.121). In addition, the resistance index was not significantly different between fertile and infertile males within the supratesticular (P = 0.486) and marginal arteries (P = 0.144). The significance of this research is that in addition to information obtained from a complete reproductive evaluation, a male camelid's fertility can be determined using testicular blood flow measured by Doppler ultrasonography.

Estimated operator exposure for hand holding portable X-ray units during imaging of the equine distal extremity.

Hand holding of portable X-ray units is common in large animal ambulatory veterinary practice. Portable X-ray equipment manuals, veterinary teaching institutions, and state regulations discourage, or prohibit, hand holding of portable X-ray units. Our goal was to quantify surface radiation leakage of a typical portable X-ray unit and to measure operator exposure at simulated hand and collar positions during imaging of the equine distal extremity. Each exposure for the study was performed at 80 kVp and 7.5 mAs and repeated 10 times. Measurement of tube radiation leakage was performed along each surface of the portable X-ray unit. To determine the operator exposure more accurately, an equine cadaver limb was used to generate scatter radiation for the following views: lateral carpus, lateral foot, palmaroproximal-palmarodistal, and dorsal 60° proximal-palmarodistal obliques of the navicular region. A Pancake Ion Chamber was placed at the handle and at simulated collar position to record estimated occupational exposure. To estimate the effect of lead shielding, exposure measurements were performed within the primary beam and behind a 0.5 mm lead equivalent apron and within an >0.5 mm lead equivalent glove. The average hand and collar dose was 0.471 and 0.327 mR/exposure, respectively. The lead apron and glove attenuated the primary beam 96.9 and 99.2%, respectively. This reduced average hand and collar exposures to 0.0038 and 0.0101 mR/exposure, respectively. Theoretical occupational limits are reached for the collar (whole body) before the hand (extremity).

Dynamic computed tomography of the normal feline hypophysis cerebri (Glandula pituitaria).

The purpose of this study was to describe normal feline hypophyseal mensuration and contrast enhancement characteristics using dynamic computed tomography (CT) imaging. An intravenous bolus of an ionic iodinated contrast medium was administered to eight cats using a pressure injector while dynamic CT images were obtained every 5 s for five cats and every 7 s for three cats for a total imaging time of 5 min. Each pituitary was measured at its maximum height and width on the peak contrast medium enhancement image. A hand-drawn region of interest was placed around each hypophysis cerebri and time attenuation curves were generated. The specific enhancement pattern of the hypophysis cerebri for each cat was recorded. The mean width and height of the hypophysis cerebri was 5.2 +/- 0.4 (average +/- SD) mm and 3.1 +/- 0.3 mm, respectively. The mean time to maximum contrast enhancement was 28.6 +/- 14.8 s (range 14-50 s) from the onset of contrast medium injection. Four cats had initial dorsal and peripheral contrast enhancement patterns of the hypophysis cerebri, while four cats had an initial central contrast medium enhancement pattern. The hypophysis cerebri had a homogenous appearance in all cats, 28-50 s after contrast medium injection. The average (+/- SD) clearance half-time was 292 (+/- 87) s. Normal hypophysis cerebri mensuration and contrast medium enhancement characteristics will help in clinical evaluation of the feline hypophysis cerebri.

Skeletal atavism in a miniature horse.

An 8-month-old miniature horse filly was presented for evaluation of severe rotational and angular limb deformities of the thoracic and pelvic limbs. On radiographic examination, complete ulnas and fibulas were identified. These findings are consistent with a condition previously described as a form of atavism. The term atavism is used to describe the reappearance of a trait or character that was seen in all earlier evolutionary specimens of a particular species, but has not been seen in recent ancestors. The atavistic traits of complete ulnas and fibulas have previously been described in Welsh and Shetland Ponies, all of which had severe rotational and angular limb deformities. In this horse, bilateral osteochondritis dissecans of the medial trochlear ridge of the talii were also identified. To the authors' knowledge, this is the first report of the atavistic traits of complete ulnas and fibulas seen in the miniature horse.