SIGNALMENT

Tommy, 3 year old neutered male domestic short hair

PRESENTING COMPLAINT

Concern for constipation – owner reports patient has been acutely vocalizing in litter box for ~1 hour with no bowel movement

PHYSICAL EXAMINATION

• QAR
• TPR: 102.7F / 185 bpm / 36 rpm
• ~5% dehydration
• Turgid, painful urinary bladder upon palpation – palpation elicits vocalization from patient
• No palpable feces in descending colon
• BP: 114 mmHg systolic via Doppler

LABORATORY TESTS RESULTS

• PCV/TS: 39% / 7.8 g/dL
• iSTAT CG8+ profile: Na⁺ 154 mmol/L, K⁺ 5.9 mmol/L, iCa 1.32 mmol/L, glucose 172 mg/dL, HCT 37%, pH 7.34, HCO₃ 22 mmol/L, BE -2 mmol/L
• POCUS (aFAST³): 0/4 abdominal fluid score; urinary bladder markedly distended with no gravity-dependent acoustic shadowing

INTERVENTIONS

• Placement of peripheral intravenous catheter to infuse a balanced electrolyte solution (e.g.: pHyLyte) at a rate to provide daily requirements (50 mL/kg/day) and correct dehydration over 12 hours
• Methadone @ 0.2 mg/kg IV
• Coccygeal epidural
• Decompressive cystocentesis

You pre-medicate with midazolam (0.2 mg/kg IV). After 5 minutes of pre-oxygenation, you induce sedation with alfaxalone (3.5 mg/kg IV to effect) to allow intubation. Sedation is maintained with alfaxalone, and the patient is provided F_iO₂ 100%. In dorsal recumbency with hips flexed, the perineum is shaved and aseptically prepared in standard fashion. Using sterile technique, the penis is extruded caudally to ensure a straightening of the S-curve of the penis. A 3.5Fr open-ended Tomcat catheter with sterile 0.9% NaCl is used to retrohydropulse the urethra in standard fashion without success.

CLINICAL ISSUE

You are unable to relieve the Tommy’s urethral obstruction.

CLINICAL QUESTION

What is the next BEST/EFFECTIVE step to relieve Tommy’s urethral obstruction?

A. Use a 5 Fr red rubber catheter to attempt de-obstruction

B. Place Tommy under general anesthesia with isoflurane or sevoflurane

C.Take into the operating room for a perineal urethrostomy

D. Infuse the urethra atracurium

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CORRECT ANSWER:

B. Place Tommy under general anesthesia with isoflurane or sevoflurane

RATIONALE 

Urethral catheterization in male cats should be performed with 3.5 Fr catheters since the use of 5 Fr urethral catheters has been associated with significantly higher rates of obstruction recurrence. Atracurium may facilitate ease of de-obstruction in some cats, but this drug is not commonly stocked in the majority of veterinary hospitals. General inhalant anesthesia induces complete relaxation of the urethral musculature, thus frequently facilitating ease of urethral catheterization. Perineal urethrostomy should not be considered until all viable modalities of urethral catheterization have proven unsuccessful.