Normal Abdominal Ultrasonography of the Horse

The cecum extends from the right paralumbar fossa to the ventral midline. It is sacculated and motility is usually more apparent than in the colons. Wall thickness is less than 4 mm and gas in the lumen precludes imaging the contents and far wall.

Gas in the cecum, right dorsal colon, or lung sometimes obscures visualization of the right kidney which can normally be found in the rostral right paralumbar fossa to the sixteenth intercostal space.8,9 The height (slightly oblique transverse plane) of the right kidney is 13 to 18 cm; its length (dorsal plane) and thickness are 13 to 15 cm and 5 cm, respectively.9 Normally it is difficult to image the ureter, though the proximal right ureter can sometimes be seen as a hyperechoic circular structure in the hilus. The right kidney architecture is similar to that described for the left kidney.

The urinary bladder, nongravid uterus, and ovaries are best imaged in the adult horse transrectally. When full, the urinary bladder may be found ventrally at the caudal most aspect of the abdomen near the pelvic brim. Owing to the presence of mucous and calcium, urine in the adult horse often appears very echogenic.

References

1. Barton MH. Equine Compendium. Submitted 2009. 2. Freeman S et al. Equine Vet J 33:570, 2001. 3. Mitchell C et al. Canadian Vet J 46:134, 2005. 4. Reef VB in Equine Diagnostic Ultrasound, Philadelphia, PA, 1998, WB Saunders. 5. Rantanen N. Vet Clin of North Amer 2:67, 1986. 6. Hendrickson E et al. Canadian Vet J 48:289, 2007. 7. Cannon J et al. Annual AAEP Convention 1995, page 39. 8. Kiper M et al. Comp Contin Educ Pract Vet 12:993, 1990. 9. Hoffman K et al. Am J Vet Res 56:1403, 1995. 10. Kirkberger R et al. Vet Rad 36:50, 1995.

Author:
Michelle Henry Barton DVM, PhD, DACVIM
University of Georgia, Athens, GA, 30602