Page 964 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Urinary system 939

VetBooks.ir 7.21 7.22

Fig. 7.21 Pyelonephritis and renal hyperaemia in Fig. 7.22 Transabdominal ultrasonogram of the
the right kidney. Note the purulent debris in the renal right kidney in a horse with pyelonephritis. Note the
medulla (arrow). hyperechogenic debris located in the distended renal
pelvis (arrow).

of renal failure in the mature horse and most often nephroliths or ureteroliths have formed and
develops as a consequence of urolithiasis, trauma, caused obstructions.
neurogenic incontinence or bladder paralysis, which
predisposes to ascending infection. Diagnosis
Urinalysis is essential. Microscopic or macroscopic
Aetiology/pathophysiology haematuria is usually present, along with pyuria.
Ascending infection from the lower urinary Bacteria may be evident microscopically; however,
tract is the usual source of bacterial colonisation. an absence of visible bacteria does not rule out
Haematogenous spread of infection to the kidneys infection. Urine culture must be performed, ide-
can also occur, although rarely. Corynebacterium spp., ally from a catheterised urine sample. A neutro-
E. coli, Proteus mirabilis, Klebsiella spp., Enterobacter philic leucocytosis is often present, as is an increase
spp., Actinobacillus spp., Salmonella spp., Pseudomonas in plasma fibrinogen. Urine is usually concentrated
spp. and Streptococcus spp. are commonly implicated (SG >1.020) unless renal failure is present, at which
in ascending infections. Haematogenous infection point isosthenuria will be identified. Azotaemia
with Leptospira spp., Salmonella spp., Actinobacillus should not be present unless renal failure has devel-
equuli and Streptococcus equi, among others, can occur. oped. Ultrasonographic examination of the bladder
With long-standing pyelonephritis, progressive and kidneys should be performed, with particular
damage of all renal structures occurs. attention paid to identification of nephroliths and
changes in renal architecture, which may be pres-
Clinical presentation ent with pyelonephritis (Fig. 7.22). Palpation p/r
Horses with pyelonephritis usually show signs of should be performed. Possible inciting causes should
a systemic disease. Weight loss, fever, PU/PD, be evaluated.
generalised weakness and depression or lethargy
are frequent presenting complaints. Concurrent Management
renal or post-renal failure may be present depend- Appropriate antimicrobial treatment is essential to
ing on the severity of renal damage and whether treat pyelonephritis and should be based on bacterial