Management and outcome of five cases of crystalluria and urolithiasis in male zoo-housed giraffes (Giraffa spp.)

Early diagnosis and intervention for crystalluria and urolithiasis in male ruminants is vital, as it can progress to obstruction leading to severe metabolic derangements, bladder or urethral rupture, and even death. Like other ruminants, male giraffes (Giraffa spp.) have a fibroelastic penis with a sigmoid flexure, narrow urethra, and a urethral process that increase their risk for urethral obstruction with urolithiasis. Additionally, zoo-housed giraffe diets have historically contained a high proportion of concentrates that can be high in phosphorus. This can result in imbalances in serum calcium:phosphorus ratio and increased risk of crystalluria and urolith formation. The first reported case of obstructive urolithiasis in a giraffe was in 2000 and was fatal. Over the past twenty-six years, additional cases have been anecdotally reported at zoological institutions but have not been described in the literature. This case series describes the diagnosis, management, and outcome for five adult male giraffes who were diagnosed with crystalluria or urolithiasis. Four of the five individuals presented with urinary obstruction necessitating surgical intervention. Of those individuals, only one survived surgery but died from a second obstructive event two months later. The other three died or were euthanized intraoperatively due to anesthetic complications. The fifth individual presented with recurrent episodes of stranguria, anuria, and crystalluria that were medically managed with diet changes and urine acidifiers. This case series provides relevant clinical information on recent cases of urolithiasis in zoo-housed giraffes and emphasizes the importance of early diagnosis and intervention given the poor prognosis once obstruction occurs.