Page 969 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

944 CHAPTER 7

VetBooks.ir tract catheterisation, urinary tract trauma, cystic cal- The selection of the antimicrobial agent should be
supported by the sensitivity of isolated bacteria, as
culi or neoplasia. E. coli, Proteus spp., Pseudomonas spp.,
Klebsiella spp., Enterobacter spp., Streptococcus spp. and
penicillin (20,000 IU/kg i/m q12 h) or trimethoprim/
Staphylococcus spp. are the most commonly identified well as the drug kinetics in the urinary tract. Procaine
pathogens. Dystocia predisposes mares to the devel- sulphadiazine (24–30 mg/kg p/o q12 h) is a good initial
opment of cystitis. If the flushing action of the voided choice. If renal failure accompanies cystitis, trime-
urine cannot clear pathogenic bacteria from the blad- thoprim/sulphadiazine should not be used. Other anti-
der mucosa, infection and inflammation can develop. microbials should be reserved for resistant infections.
Cystitis requires a prolonged period of antimicrobial
Clinical presentation treatment. Repeated urinalysis should be performed
Dysuria, stranguria and pollakiuria are the most to assess response to treatment. Antibiotic treatment
common presenting complaints. Signs of gener- should continue for 1 week after urine bacterial cul-
alised disease such as fever, depression or weight loss ture is negative. Relapses are common.
should not be present with uncomplicated cystitis, Adding 50 g of table salt daily to the diet will
as opposed to pyelonephritis. Urine scalding may be encourage horses to drink more, which will cause
observed on the perineum or hindlimbs. diuresis and an increase in the elimination of harm-
ful bladder content. Free access to water is essential.
Differential diagnosis Bladder irrigation (0.9% NaCl) is beneficial in cases
Differential diagnoses include urolithiasis, blad- with cystic calculi or excessive amount of sediment.
der paralysis, neoplasia, renal failure, colic and This is best performed using endoscopy to minimise
pyelonephritis. traumatic bladder irritation.

Diagnosis Prognosis
Physical examination findings typically suggest uri- The prognosis is good for primary cystitis. Chronic
nary tract disease but are not specific for cystitis. cystitis, recurrent cystitis, ascending infection into
Haematology is usually unremarkable. Diagnosis is the proximal urinary tract and neoplasia have a less
based on urinalysis. Pyuria (more than 5 WBCs/ favourable long-term prognosis.
hpf) is usually associated with cystitis. Bacteria may
be evident on cytological analysis of urine sediment, BLADDER TUMOURS
but absence of visible bacteria does not rule out an
infectious cause. Microscopic or macroscopic haema- Definition/overview
turia may be present. Urine is usually concentrated Bladder tumours are rarely diagnosed in horses and
(SG >1.020). Bacterial culture should be performed. are associated with a very poor prognosis.
A catheterised sample is preferred to avoid contami-
nants. Quantitative culture should be requested, Aetiology/pathophysiology
where available, with identification of >10,000 colony Bladder tumours are usually identified in older horses
forming units (CFU)/ml in a catheterised sample although fibromatous polyps are more common in
indicating infection. Palpation p/r should be per- younger horses. Bladder squamous cell carcinoma is
formed to evaluate the bladder wall and determine the most common followed by transitional cell car-
whether uroliths may be present. Endoscopy of the cinoma. Non-epithelial primary bladder tumours
bladder via cystoscopy or ultrasonography may be include tumours of muscle, vascular and fibroblastic
helpful for investigation of primary disease. tissues and lymphomas. Metastases from other com-
mon neoplasias can occasionally involve the bladder.
Management
The inciting cause should be identified and treated, Clinical presentation
if possible. The use of an appropriate antimicrobial Clinical signs of disease are not usually evident
agent is essential for successful management of cystitis. until the disease is well advanced. Weight loss and