Urethral obstruction in a ram with a periurethral abscess: clinical findings, diagnostic imaging and pathology

Urethral obstruction is a common and life-threatening condition in male small ruminants.

This case report describes a 3-year old 103 kg Zwartbles breeding ram, presented with the complaint of straining, suspected to have an urethral obstruction. The work-up included clinical examination, laboratory analyses, ultrasound imaging, (contrast) radiography and urine examination. At presentation, blood analysis revealed a respiratory alkalosis, hyperkalaemia and mild azotaemia. On transabdominal ultrasound an enlarged bladder (diameter 11 cm) and free fluid surrounding the right kidney were observed. Treatment of the animal included tube cystostomy, intravenous perfusion, antimicrobial treatment, ammonium chloride and NSAIDs. No indications for urolithiasis were found on ultrasound, radiography, or urine examination. As no improvement was seen despite 16 days of therapy, a contrast radiograph of the urinary tract, as well as reproductive exam were conducted. Positive anterograde urethrogram showed a contrast filled cavitary lesion at the caudal aspect of the pelvic urethra. The reproductive ultrasonography revealed the same large urethral distention or abscess compressing the pelvic urethra, as well as severe testicular degeneration in both testis. The results of the contrast radiograph and the reproductive exam lead to the decision to euthanize the animal, as the animal would not be capable of breeding. Computed tomography was performed post-mortem, which showed close relation between the cavitary lesion and the left bulbourethral gland. Pathology revealed a lymphoplasmacytic to suppurative infection at the level of the urogenital tract, chronic interstitial nephritis and a perirenal to cortical abscess of the right kidney as well as a periurethral abscess. As for the reproductive system, multifocal interstitial inflammatory infiltrates were seen on the entire system. Marked fibrosis and atrophy was seen at the level of the testes and both epididymides.

A periurethral abscess should be included in the differential diagnosis for an urethral obstruction in small ruminants. The extensive medical imaging, together with the ante-mortem and post-mortem findings, makes this a good reference case for diagnosticians confronted with urethral problems in a ram.