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Chapter 28: Guidelines for Postoperative Medical Care of the Neurosurgical Patient 251

A Table 28.3 Pharmacological agents used in bladder management.
Drug Dogs Cats
Phenoxybenzamine 0.25–0.5 mg/kg PO every 2.5–7.5 mg/cat PO every
12–24 hours 12–24 hours
Prazosin 1 mg/15 kg PO every 8 hours 0.25–0.5 mg/cat PO
every 12–24 hours
Diazepam 0.25–1.0 mg/kg PO every 8 0.5 mg/kg IV
hours; 0.5 mg/kg IV
Bethanechol 5–15 mg PO every 8 hours 1.25–7.5 mg PO every 8
hours
Source: Doses modified from Plumb’s Veterinary Drug Handbook [20].

Long‐term Management of the Bladder
In cases of IVD herniation where there is loss of deep pain, return
of voluntary urination can be variable, with some patients never
regaining normal function. In these cases, the owners need to learn
to express the urinary bladder to limit complications from overflow
B including urine scalding, atonic bladder, and recurrent UTIs.
Owners can develop the necessary skills to express the urinary
bladder and also to assist in defecation if desired. Early instruction
in bladder expression is recommended when long‐term urinary
dysfunction is expected.
Pharmacological agents that can be used to assist in bladder
expression and treatment of urethral spasm and atonic bladder
include phenoxybenzamine, prazosin, diazepam, and bethanechol
(Table 28.3).
Phenoxybenzamine is an α‐adrenergic blocker used for detrusor
areflexia that acts by reducing internal urethral sphincter tone, but
can also cause hypotension. Alternatively, prazosin, an α blocker,
1
has been used in both dogs and cats to decrease urethral resistance.
Diazepam has been used as a muscle relaxant for functional ure-
thral obstruction and urethral hypertonus. Use of oral diazepam in
cats is controversial as there is a risk of hepatotoxicity if given orally
over prolonged periods. Bethanechol is a synthetic cholinergic ester
that is used to increase bladder contractility. It has also been used
previously as a general gastrointestinal stimulant. Side effects that
can be seen with its use are secondary to its muscarinic effects and
include salivation, lacrimation, urination, and defecation.
Bethanechol should be used in conjunction with medications that
decrease urethral tone to reduce the risk of bladder rupture [20].
Despite the best efforts to completely evacuate the bladder, in
some cases UTIs can recur. A UTI should be treated early with anti-
biotics based on urine bacterial culture and sensitivity of a sample
obtained by cystocentesis [41]. If there are recurrent UTIs, longer‐
term management using nitrofurantoin or cranberry tablets can be
considered. At low doses, nitrofurantoin is a bacteriostatic antimi-
Figure 28.4 (A) Indwelling male urinary catheter immediately after aseptic crobial that is considered a urinary antiseptic (prophylactic dose
insertion but prior to suturing and installation of the drainage system. (B) 3–4 mg/kg orally every 24 hours) [37]. Approximately 40% of the
Closed sterile urinary collection system attached to an indwelling urinary drug is eliminated in the urine unchanged with no gastrointestinal
catheter. Notice that the collection system is placed in a clean container, not side effects.
on the floor.

polydipsic or polyuric, and no longer on intravenous fluids, Nutritional Requirements
bladder expression can typically be performed at 6–8 hour The need for postoperative nutritional supplementation is influ-
intervals. It is important to monitor the patient for complete enced by the preoperative neurological status, the type of surgery
voiding of the bladder as partial expression or overflow inconti- performed, and the expected time until appropriate nutritional
nence is often mistaken for voluntary urination. If urine is found intake returns. In most cases of IVD disease, the patient was neuro-
in the cage, bed or following voluntary urination, the bladder size logically normal prior to herniation of the disc and the period of
should be verified by manual palpation or ideally using ultrasound perioperative anorexia is short. Nutritional supplementation in
to ensure complete voiding has occurred. these patients is typically not necessary as normal appetite returns