Urinary Calculi of Small Ruminants

Urolithiasis is a multifactorial disease of male ruminants causing significant economic loss and compromise of animal welfare. Known risk factors include anatomic factors, urine pH, water intake, dietary composition, and genetic factors. Clinical cases of obstructive urolithiasis may be treated using a variety of medical and surgical interventions, including tube cystostomy, perineal urethrostomy, urinary bladder marsupialization, and modifications of these procedures designed to optimize patient outcome.

Imaging of the Urinary and Reproductive Tract in Small Ruminants

Ultrasound imaging is the mainstay of urinary and reproductive imaging in small ruminants, assisted by the relatively superficial location of the urinary and reproductive tracts in these species. Radiography can provide an excellent overview of the abdomen, but is often limited by a lack of adequate penetration. Computed tomography scans provide summation-free imaging of the urinary and reproductive tracts in addition to information about the excretion of contrast agent by the kidneys, but can be limited by availability and cost.

A pilot study to assess the feasibility of endoscopic placement of a transurethral urinary balloon catheter in male sheep cadavers

Surgery of obstructive urolithiasis in small ruminants is often unsatisfactory due to postoperative development of strictures. The present study aimed to establish an endoscopic technique for the placement of a transurethral urinary catheter into the bladder of rams. This catheter was used as a removable stent-like drainage. The procedure was performed in three sheep rams that were euthanized and placed for surgery in 45° Trendelenburg position. In one ram, cystotomy was performed via right paramedian laparotomy. A 3 mm flexible fiberscope was introduced into the urinary bladder and advanced via urethra to the tip of the penis. Placing a guide wire through the endoscopic working channel into the urethra enabled the retrograde insertion of a transurethral urinary catheter into the bladder. In two rams, retrograde insertion of a fiberscope was performed. Again, a guidewire was used to insert a balloon catheter into the bladder. Paramedian right laparotomy was performed to ascertain the correct position of the balloon. Both techniques, antero- and retrograde endoscopy, were possible and could be successfully performed. Mucous membranes and urinary microliths were easily observed. Repeated advancing of the endoscope or the catheter resulted in marked damage of the mucous membranes. The patency of the urethra may be restored by means of endoscopic placement of a transurethral catheter in male small ruminants. The applicability and clinical outcome of this procedure as well as the effects on stricture formation should be further examined with controlled clinical studies.

Variables of initial examination and clinical management associated with survival in small ruminants with obstructive urolithiasis

BACKGROUND

Obstructive urolithiasis is a common disease associated with a guarded prognosis in small ruminants.

HYPOTHESIS/OBJECTIVE

The results of physical examination, laboratory analyses, and clinical management of male small ruminants presented to 2 referral clinics were investigated to identify variables significantly associated with disease outcome, so as to provide better recommendations to animal owners regarding the management of these patients.

ANIMALS

Two-hundred ten small ruminants (130 sheep and 80 goats) with confirmed diagnosis of obstructive urolithiasis.

METHODS

Clinical findings (including diagnostic imaging) and laboratory results of the 210 animals were reviewed, and relevant information regarding clinical and laboratory variables recorded upon admission and clinical management was retrieved. The association of the different variables with nonsurvival was investigated by univariable and multivariable logistic regression models.

RESULTS

Only 39% of all patients considered for treatment and 52% of those undergoing tube cystostomy survived to be released from the clinic. Nonsurvival was strongly associated with a very poor clinical condition upon presentation, obesity, castration, and evidence of uroperitoneum. Among blood variables, abnormal PCV, severely increased serum creatinine concentrations, and increased activity of the creatine kinase were associated with increased risk of nonsurvival. Presence of signs of colic or macroscopic appearance of urine was not significantly associated with outcome.

CONCLUSIONS AND CLINICAL IMPORTANCE

The prognosis of obstructive urolithiasis was guarded with survival rates of 39% (overall) to 52% (after tube cystostomy). Intact young males with normal body condition presented early in the course of disease had the best chances of survival.