A retrospective study published in JAVMA by a veterinary specialty hospital in collaboration with University of Pennsylvania selected 71 cats (mostly domestic shorthairs) to help determine whether using ultrasonography could show there was a ureteral obstruction and help determine the cause and location of the problem.
The results showed that ultrasonography was quite good for identifying ureteroliths (stones in the ureter causing blockage). It was less helpful for cats with ureteral strictures, such as a blood clot partially blocking a ureter.
Currently, x-rays and contrast dyes are used. Radiologists try to evaluate cats without any sedation, but that can mean studies are sensitive to movement of the cat while being evaluated. Fat in the abdomen along with intestinal loops can all interfere with a clear look at the ureters, plus feline ureters are quite small to begin with. In many cases, though, the ultrasound results were able to help veterinary surgeons develop their treatment plan.
The researchers noted that these ultrasounds were done by experienced board-certified veterinary radiologists and had many cases available to them via the referral nature of the hospitals. In routine practice, a veterinarian may not get much experience doing these studies. Still, more research into this area could lead to faster, safer ways to diagnose ureteroliths in cats and to differentiate them from strictures of various types.
JAVMA 3/15/2019 Vol 254 #6