Page 976 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Urinary system 951

VetBooks.ir 7.31 7.32

Fig. 7.31 Urethrolith (arrowed) in the urethral Fig. 7.32 Stranguria in a horse with urethrolithiasis.
orifice. Urethrolithiasis is usually associated with
urinary calculi in the bladder or proximal urinary
tract. (Photo courtesy VK Kos)

more distally and completely obstruct the urethra, thorough palpation of the intestinal viscera should
causing signs of renal colic. If not treated, bladder be performed. An inability to pass a urinary cath-
rupture, uroperitoneum and post-renal AKI may eter is suggestive of urethral obstruction although
develop. urethral spasm can also inhibit advancement of a
catheter. Urethroscopy usually provides a definitive
Clinical presentation diagnosis.
Frequent posturing to urinate, pollakiuria, strangu- Urinalysis, if urine can be obtained, is consistent
ria (Fig. 7.32) and non-specific signs of abdominal with signs of post-renal AKI. Urethral defects result
pain are common signs of urethrolithiasis. Blood in haematuria noted at the end of urination. Bacterial
may be seen at the end of the urethral orifice. The culture of the urine should be performed. Initially,
severity of clinical signs depends on whether com- haematology should be unremarkable. If bladder
plete urethral obstruction is present. With complete rupture ensues, then the horse becomes depressed
obstruction, signs of severe abdominal pain will and anorexic because of acid–base alterations and
develop as bladder distension progresses. If the blad- azotaemia. The rest of the urinary tract should be
der ruptures, signs of uroperitoneum develop. examined for the presence of other uroliths.

Differential diagnosis Management
Differential diagnoses include urethral trauma, neo- Calculi that are present in the distal urethra may be
plasia, urethritis, cystitis, sabulous urolithiasis, blad- removed with haemostats (Fig. 7.33). Calculi lodged
der paralysis and colic. further up the urethra can be removed via a ure-
throstomy (Fig. 7.34). Those lodged at the ischial
Diagnosis arch can be removed through a perineal urethros-
The penis should be extended and carefully palpated. tomy (ischial urethrostomy, subischial urethros-
Blood may occasionally be seen on the end of the tomy). Calculi can be crushed and then removed
urethra on examination of the penis. Urethroliths from the urethra. However, trauma can be sustained
may be palpable, depending on the location. The by the urethra and bladder during such procedures.
bladder should be palpated p/r to assess bladder Calculi lodged in less accessible parts of the urethra
size. The bladder may be turgid and distended. If may require a urethrotomy performed under general
signs consistent with abdominal pain are present, anaesthesia.