Medical records of 68 horses with urolithiasis were examined. Calculi were in the bladder in 47 horses, urethra in 11 horses, kidneys in 15 horses, and ureter in two horses. They occurred at several sites in six horses. Common clinical signs included hematuria, altered micturition (pollakiuria, dysuria, urinary incontinence), and tenesmus. Weight loss, possibly attributable to chronic renal failure and colic, was associated more commonly with renal and ureteral calculi. Weight loss also occurred in 13% of horses with cystic calculi only. In male horses, most cystic calculi were removed by perineal (ischial) urethrotomy under epidural anesthesia. Although there were few surgical complications with urethrotomy, seven of 15 horses with follow-up suffered recurrent urolithiasis.

Selected information was compiled from canine urinalyses and urine cultures conducted between January 1969 and December 1995. Eight thousand three hundred fifty-four microbial isolates (bacteria and fungi) included 4,873 isolates from females and 3,481 from males. Ten bacterial genera accounted for 96.3% of the urinary isolates, including Escherichia coli (44.1%), Staphylococcus spp. (11.6%), Proteus spp. (9.3%), Klebsiella spp. (9.1%), Enterococcus spp. (8.0%), and Streptococcus spp. (5.4%) as the 6 most common isolates in both genders of dogs. Among these 6 genera, female dogs were generally predisposed over males, although males had more urinary tract infections (UTIs) caused by Klebsiella spp. Distributions of ages at UTI diagnosis tended to be similar between genders. Infection with a single microbial species was responsible for >72% of UTIs in both genders. Among females, 40 breeds and a mixed-breed group represented 90.2% of all positive urine cultures, 88.4% of the individual dogs with UTIs. and 88.2% of the microbial isolations. Among males, these same 41 breed groups represented 87.9% of all positive urine cultures, 87.6% of the individual dogs, and 88.2% of the microbial isolations.

An increase in the proportion of CaOx uroliths submitted over time was detected. Reasons for long-term changes in this trend were likely multifactorial and could have included alterations in diet formulations and water consumption and possibly the fact that people favor ownership of breeds more prone to developing CaOx-containing uroliths. The decrease in metabolic uroliths could have been related to better breeding practices and increased awareness of results of genetic studies.

The increasing proportion of calcium oxalate uroliths was in accordance with findings from other studies and could be a result of alterations in cats' diets. However, the decreased percentage of calcium oxalate calculi and increased percentage of struvite calculi observed in the last 3 years may portend a change in the frequency of this type of urolith.

Laboratory records of bacterial urine cultures from 383 dogs with recurrent or persistent urinary tract infections (UTI) diagnosed at the University of California Veterinary Medical Teaching Hospital (VMTH) between 1969 and 1995 were reviewed retrospectively to characterize the bacteria involved and their association with age, gender, and breed of dogs affected. Sixty-eight breeds and a mixed-breed group were represented. Escherichia coli was the most common isolate, although mixed-bacterial infections were seen in 58% of the female and 55% of the male dogs. Recurrent and persistent UTI were most prevalent in middle-aged to older German shepherd dogs, miniature/toy poodles, and Labrador retrievers, with no apparent sex predilection. Criteria fitting recurrent and persistent UTI were present in 0.3% of all dogs seen at the VMTH during this 26-year period.