Urinary tract obstruction in small animals Flashcards
intra-urethral causes
calculi
tumours
infl disease
foreign body (rare)
extra-urethral causes
bladder/pelvic masses
prostatic disease
trauma
bladder displacement
retroflexion - perineal rupture
due to abdominal wall rupture/pelvic fractures
bladder torsion
neurogenic causes of urine retention - LMN (lower motor neurone)
flaccid, overdistended bladder, urine leakage can't voluntarily urinate congenital cauda equina syndrome lumbo-sacral disease vertebral fractures
neurogenic causes of urine retention - UMN (upper motor neurone)
firm, tense bladder that is hard to express
lesions cranial to sacral nerve segments
intervertebral disc disease
functional urethral obstruction
aka reflex dysynergia
pass small spurts of urine + have large residual volume
want to urine but can’t coordinate nervous stimulation
treat medically
clinical signs
inability/difficulty passing urine - anuria, dysuria, stranguria, tenesmus
may have - vulval/penile bleeding, haeaturia, vomiting
if collapse can be mistaken for other diseases
clinical findings
full bladder - unless ruptures
can’t pass catheter - not reliable
possible palpable mass
abdo pain, depression, unproductive straining, abdo distension
pathophysiology - obstructive uropathy
incr ureteral + tubular pressure
incr pressure in bowmans space
GFR falls
decr renal blood flow keeps GFR low
ischaemic nephropathy - effect
may result in permanent nephron loss
effects on bladder
overdistension
incr intravesical pressure stops ureteral emptying - ureteral reflux
ischaemia, oedema, haemorrhage + mucosal sloughing
systemic effects - biochemical changes
hypovolaemia, hypotension
azotaemia, hyperglycaemia, acidaemia, hyperphosphataemia, hypocalcaemia , hyperkalaemia (life threatening)
hyperkalaemia - effects on the heart + eCG
prolonged PR interval, tall or peaked T wave
bradycardia, sino-ventricular rhythm
ventricular arrythmias
emergency management
treat hyperkalaemia
blood sample
place IV catheter + start IVFT
ECG if hyperkalaemic or if K+ unknown
treating hyperkalaemia
fluid therapy - decr conc of K+
calcium gluconate - stabilises myocardium, improves arrythmias
relieve obstruction
cystocentesis - cons
risk of urine leaking to abdominal cavity
can result in septic peritonitis + death
cystocentesis - pros
allows stabilisation of patient - temporary relief of obstruction
decr hydrostatic pressure in the bladder facilitates catheterisation
cats have sterile urine - low risk of septic peritonitisf
urethral catheter - how to place
sedate/GA lubrication penile massage flushing try avoid cather with a stylet
after unblocking - what next?
save urine for urinalysis
bladder lavage - warm saline, flush until clear
when removing catheter express bladder and check urine stream
can place indwelling catheter + closed collection system
indwelling catheters
not always needed never well tolerated retained by suture/inflateable bulb placed aseptically no antibiotics until catheter removed
therapeutics after obstruction relieved
fluid therapy
biochemistry/blood gas/electrolyte measurement
investigate/further management
what to monitor for
post obstruction diuresis urinary tract infection detrusor atony bladder outflow obstruction secondary to blood clot/sloughed mucosa stricture
pharmacological therapy
smooth + skeletal muscle relaxants phenoxybenzamine prazosin dantrolene diazepam
retrograde hydropropulsion
flush urethral calculi into bladder - then removed by cystotomy/laparoscopic cystotomy
can combine with urethrography
if can’t pass catheter - cystocentesis
surgical management choices
remove calculi - cysto/urethrotomy
urinary diversion - cystotomy tube, urethrotomy
re-establish urethral patency - end-to-end anastomosis
urethrotomy
only when hydropropulsion not effective
more complications than cytotomy
primary closure best
cystotomy tube
tube in bladder across the body wall
allows urine to drain - by-pass urethra
can be used for short + long term
cystotomy tube - indications
to drain urine if catheter can’t be placed
protect the urethra
palliative treatment for severe urethral disease
urethrostomy
permanent opening in urethra
to pass obstruction/pass stones/sediment
must be done cranial to obstruction
modern techniques
urethral stenting - strictures/tumours
balloon dilation - strictures
endoluminal lithotripsy - calculi
endoluminal resection/ablation - tumours
surgery options for kidney
nephrotomy
pyelolithotomy
