Urinary Tract Obstruction in Small Animals Flashcards
Where in the UT is the most common place for obstruction? What are the likely causes?
Urethra
+ Uroliths
+ Urethral lesions
+ Organ displacement
What can cause UUT obstruction? When do the clinical signs occur?
Calculi
Trauma
Clinical signs when bilateral
If calculi are seen on radiographs, how can you confirm they are obstructive?
Additional imaging - US, contrast radiography
Give 4 examples of intraurethral causes of obstruction
Calculi
Tumours
Inflammation
FB (v rare)
Give 4 examples of extraurethral obstructions…
Bladder mass
Pelvic mass
Prostatic disease
Trauma, surgery
What changes happen to the bladder as a result of obstruction?
Retroflexion
Displacement
Bladder torsion
What causes LMN urine retention? Where is the lesion found/
Cauda equina syndrome
Lumbosacral disease
Vertebral fractures
L5 and caudal
What are the clinical signs of LMN urine retention?
Flaccid, overdistended bladder
Easy to express
Urine leakage (esp when picked up)
What can cause UMN retention of urine? Where is the lesion found?
IVDD Neoplasia Luxations Fractures Cranial to L5
What are the clinical signs of UMN urine retention? How can it be expressed?
Firm, tense bladder
Difficult to express
Relaxation of urethral sphincter
Outline functional urethral obstruction (reflex dsynergia)
D > C but rare
Pass small spurts of urine, large residual vol
Dysnergia between detrusor contraction and urethral relaxation
Are M or F more likely commonly affected by obstruction?
Male
What are the clinical signs of urinary obstruction?
Anuria, dysuria, stanguria
Apparent constipation
Vulval/penile bleeding/haematuria
V+
What are the clinical signs of urinary obstruction on PE?
Full bladder Inability to pass cath Palpable mass in pelvic region Abdo pain Depression Unproductive straining Abdo distension
Outline the pathophysiology of urinary obstructions
Urine not excreted fully > increase urethral pressure > increased tubular pressure > increased pressure in bowmans capsule > Decreased GFR> reduced renal blood flow > ischaemic nephropathy > permanent nephron loss
How do UT obstruction affect the bladder?
Increased pressure in bladder > ureters dont empt properly > ureteral backflow
Ischaemia, oedema, haemorrhage and mucosal sloughing
How does urinary obstruction result in system hypovolaemia?
Local vasodilation
Fluid loss in V+, faeces, sensible losses
What biochemical changes are expected with obstructions? Are these changes reversible?
Azotaemia Hyperglycaemia Acidaemia Hyperphosphataemia Hypocalaemia Hyperkalaemia
What cardiac effects does hyperkalaemia have?
Prolonged PR interval, tall/peaked T waves
Bradycardia
Ventricular arrhythmias
What level of hyperkalaemia becomes a life threatening emergency?
K 8mEq/L
How is hyperK treatment? What is the aim of treatment?
IVFT
Ca gluconate
Relieve obstruction
Stabilise the myocardium so condition is no longer life-threatening
What are the dis/advantages of decompressive cystocentesis?
+ Temporary relief and stabilisation
+ Facilitate catheterisation
+ Risk of infection in cats v low
- Risk of urine leaking into the abdo cavity -> septic peritonitis
Outline how a urinary obstruction might be relieved…
- Patient is stable GA/sedation
- Lubricate catheter
- Stay sutures or allis forceps hold back prepuce
- Flush well with warm saline
- Float catheter into bladder
Why shouldn’t ABs be used with an indwelling catheter?
Don’t prevent infection and only cause resistence
