Epidemiology of feline urethral plugs: 1981-2005

Of 593 urethral plugs submitted to the Minnesota Urolith Center by veterinarians in 2005, the mineral composition of almost 87 percent were primarily struvite (Figure 2). Less than 1 percent were composed of calcium oxalate. Since 1981, struvite has consistently been the most common mineral in feline urethral plugs; the prevalence of calcium oxalate in urethral plugs always has been infrequent (Table 2). The explanation as to why there have been significant shifts in the prevalence of calcium oxalate and struvite in feline uroliths during the past 25 years while the prevalence of struvite and calcium oxalate in feline urethral plugs has not significantly changed is not obvious. However, the high prevalence of struvite in urethral plugs is of clinical significance in terms of dietary strategies to prevent their formation.

Dr. Osborne, a diplomate of the American College of Veterinary Internal Medicine, is professor of medicine in the Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Minnesota.