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Chew 1987). Observing up to eight white blood cells per high-powered field is considered normal when cytologically examining urine collected when the horse urinates. Inability to identify bacteria during cytological examination of urine does not preclude the presence of bacteria in the urine. Pyuria can
Fig 2: An endoscopic view of the urethra of a gelding with terminal haematuria is shown. A urethral rent is seen in the 8 o’clock position.
presence of a vascular anomaly (Schott et al. 1996), and angiography performed during computed tomographic imaging was helpful in identifying a vascular abnormality in a 5-week-old colt, indicating that contrast-enhanced, cross- sectional imaging of the abdomen might be valuable in facilitating an accurate diagnosis of a renal vascular anomaly (Nogradi et al. 2013). Gross and cytological examination of the urine of horses
with haematuria often identifies the probable site or cause of haemorrhage. Urinalysis is occasionally helpful in determining the cause of haematuria. Urine for cytological examination should be collected midstream and end-stream, so that nondiagnostic cellular debris in the urethra is eliminated before collection. Cells associated with disease of the bladder settle in the bladder so are more likely to be found in an end-stream sample, whereas cells indicative of disease of the upper portion of the urinary tract are more likely to be found in urine collected midstream. Pyuria is usually defined as a WBC of at least 10 WBCs/
mm3 or more than five WBCs per high-powered field, when examining urine collected by catheterisation (Kohn and
be caused by infectious or sterile inflammatory conditions, but finding clumps of WBCs increases the probability that infection is the cause of pyuria (Kohn and Chew 1987). Pyuria and associated haematuria may be associated with primary cystitis or pyelonephritis, and either of these conditions may be secondary to another condition, such as urolithiasis. Neoplastic cells have been found in urine of horses with haematuria caused by cystic neoplasia (Fischer et al. 1985; Sweeney et al.1991), and a nematode may be found during urinalysis of horses with haematuria caused by the presence of Halicephalobus gingivalis in the kidney (Mayhew 1989). Eosinophils can be found in the urine of horses with haematuria caused by migration of larvae of Strongylus vulgaris through the kidney (Mahaffey and Adam 1963). Pyelonephritis may be a cause of haematuria (Kisthardt
et al. 1999; Schott and Woodie 2012), and bacterial culture of renal tissue obtained by biopsy and testing of isolates for antimicrobial susceptibility may facilitate selecting an appropriate antimicrobial drug for treatment; culture of pathogenic bacteria provides supporting evidence that haematuria is caused by bacterial pyelonephritis. Renal biopsy can be performed using ultrasonographic guidance, or it can be performed blindly, after ultrasonographically measuring the distance from the skin to the kidney’s capsule. The left kidney is more difficult to biopsy than the right kidney, because the left kidney is further from the abdominal wall and because, when biopsying the left kidney, the spleen must sometimes be penetrated to obtain renal tissue. Haematuria resulting from renal biopsy may be evident for several days. Renal biopsy is usually a safe procedure. The most common complications are haematuria, pain and fever; death caused by exsanguination is rare (Tyner et al. 2011). Biopsy of a mass within the bladder obtained using an endoscopic cut biopsy forceps is often nondiagnostic, because of the small size of harvested specimens (Hurcombe et al. 2008). A mare uterine biopsy instrument can easily be passed into the bladder of a mare to obtain tissue for histological examination; this instrument can be passed into the bladder of a male horse through a perineal urethrotomy (Fischer et al. 1985).
Authors’ declaration of interests No conflicts of interest have been declared.
Ethical animal research
No ethical review was required as this paper was merely a review of case reports.
Source of funding None.
Fig 3: Polyethylene tubing passed through the biopsy port of an endoscope has been inserted into a ureter.
© 2017 EVJ Ltd
Authorship The authors shared equally in the preparation of this manuscript.
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