Page 973 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

948 CHAPTER 7

VetBooks.ir atrophy, penile prolapse and perineal sensory defi- is indicated in recumbent animals, if urinary tract
infection is suspected or if frequent urinary cath-
cits are most commonly associated with UMN
disease. Haematuria may be observed if second-
IU/kg i/m q12 h) or trimethoprim/sulphadiazine
ary infection or urolithiasis has developed. Less eterisation is required. Procaine penicillin (20,000
commonly, signs of systemic infection may be (24–30 mg/kg p/o q12 h) is a good initial choice.
present if upper urinary tract infection has devel- Intravenous fluid therapy, if required because of con-
oped. Bladder dysfunction is often associated with current disease or dysphagia, should be used conser-
the accumulation of large amounts of sabulous or vatively, particularly if UMN bladder dysfunction is
mucoid urinary sediment, especially so in myogenic present.
bladder dysfunction and, less often, in LMN dis- It is important to consider whether UMN or
ease. Severe and chronic dysfunction of the bladder LMN lesions are present. Phenoxybenzamine
wall can lead to permanent dysfunction. Ammonia (0.7 mg/kg p/o q6 h) can be used in cases of UMN
accumulation in the bladder lumen causes constant disease to decrease urethral sphincter tone although
irritation that further damages the bladder wall and the effectiveness of this treatment is unclear.
musculature. Bethanecol chloride (0.025–0.075 mg/kg s/c or
0.2–0.4 mg/kg p/o q8 h) can be administered to
Differential diagnosis improve detrusor muscle tone and strengthen blad-
Differential diagnoses include urolithiasis, cystitis, der contraction. The response to bethanecol is usu-
neoplasia, renal failure, cantharidin toxicosis, ecto- ally poor with long-standing disease, and it should
pic ureter and various neurological diseases. be discontinued if there is no response within 3–5
days. Bethanecol has no effect when the bladder
Diagnosis is completely atonic or areflexic. Acepromazine
A detailed neurological evaluation is essential to (0.02–0.05 mg/kg i/m q8 h) and diazepam (0.02–0.1
localise the lesion and identify the primary cause. mg/kg; slow i/v administration) may decrease ure-
An LMN bladder is flaccid and easily expressible, thral tone and help to void urine.
while exaggerated sphincter tone in a UMN blad-
der results in firm distension. Sabulous urolithiasis Prognosis
may also be palpable p/r. Transrectal and/or trans- The prognosis is guarded and depends on the abil-
abdominal ultrasonography and cystoscopy are help- ity to treat the primary disease and prevent compli-
ful for eliminating other causes of incontinence and cations such as urinary tract infection or sabulous
urine dribbling. Specific diagnostic testing for indi- urolithiasis.
vidual neurological diseases is covered elsewhere (see
Chapter 10). NON-NEUROGENIC AND
Haematology is typically unremarkable unless NON-MYOGENIC INCONTINENCE
there is bladder rupture or secondary upper urinary
tract infection is present. Urinalysis is normal unless Cystitis and chronic urethritis can cause apparent
secondary infection or urolithiasis has developed. incontinence through irritation of stretch receptors
Urine culture should be performed in all cases. in the bladder wall. In cases of urine retention, bac-
teria can break down urea to ammonia, which acts as
Management an irritant on the bladder mucosa and musculature,
Management of the underlying disease should be causing incontinence. Ectopic ureters, urethral or
instituted promptly. The bladder should be regu- vaginal injury and vaginal polyps have been asso-
larly evacuated, which will help prevent exacerba- ciated with incontinence. Hypo-oestrogenism in
tion of bladder atony and development of sabulous mares has also been reported as a possible cause of
urolithiasis. Nursing care, including daily cleaning incontinence.
of the perineum and hindlimbs, is required to reduce The pathophysiology, clinical signs and man-
skin irritation. Prophylactic antimicrobial treatment agement of non-neurogenic and non-myogenic