Page 971 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

946 CHAPTER 7

VetBooks.ir Diagnosis cystotomy are commonly performed (Fig. 7.26).
Subischial urethrotomy can be performed in a
Urinalysis, haematology and serum biochemistry
should be performed to document accompanying
diverticulum formation at the incision site is a dis-
problems of the proximal urinary tract. The urine standing horse but the potential for stricture or
should be concentrated. Proteinuria, microscopic advantage of this procedure. In mares, manual
haematuria and pyuria are common. A catheterised distension of the urethra may permit removal of small
urine sample should be submitted for bacteriologi- stones. Urethrosphincterotomy can be performed
cal culture, with identification of >10,000 CFU/ml to aid the passage of fingers or a small hand into
indicating concurrent urinary tract infection. No the bladder. Some stones may be crushed with for-
haematological abnormalities should be present with ceps placed within the bladder to facilitate removal.
uncomplicated cases. Sedation and epidural anaesthesia are required for
Calculi and/or a thickened bladder wall may be the procedure. Fragmentation and removal of cys-
palpable p/r. If the bladder is urine filled, it should tic calculi by electrohydraulic lithotripsy, ballistic
be decompressed to allow for thorough palpation. shock lithotripsy and laser lithotripsy have also been
Depending on the degree of concurrent bladder-wall reported. Pararectal cystotomy (Gökel operation)
inflammation, pain may be noted during palpation can aid successful removal of calculi although there
of the bladder. Sabulous urolithiasis consists of an are significant postoperative complications.
accumulation of sand-like debris in the bladder that Antimicrobial therapy, as described for cystitis,
may feel ‘doughy’ on palpation. Ultrasonographic should be initiated if evidence of bacterial infection
examination of the urinary tract should be per- is present on urinalysis and urine culture, and always
formed to exclude the presence of calculi in other when the procedure of calculi removal is performed.
locations. Cystoscopy can be used to further evalu- Urinary acidification is used in other species to
ate cystoliths (Fig. 7.25) or sabulous urolithiasis. reduce urolith formation, but it has proven to be
of minimal use in horses. Oral administration of
Management ammonium chloride (25–50 g/horse/day) or vitamin
Several techniques have been described for removal C (2 g/kg/day) has had inconsistent effects. Higher
of cystic calculi. Laparocystotomy or laparoscopic doses of ammonium chloride (520 mg/kg/day)

7.25 7.26

Fig. 7.25 Solitary cystolith in the bladder of a horse Fig. 7.26 Laparocystotomy: surgical removal of a
with dysuria. Note the roughened surface of the cystolith. (Photo courtesy A Cruz)
cystolith and the bloody urine.