Science Digest: What are the risk and protective factors for the development of clinical urolithiasis in guinea pigs?

11 September 2025

Urolithiasis is common in guinea pigs and, amongst urogenital disorders, is the main cause of clinical disease in pet guinea pigs. However, there has been little research on the etiopathogenesis and prevention of urolithiasis in guinea pigs, and understanding risk factors might help reduce its incidence and the need for surgical interventions.

A new study, by researchers at the School of Veterinary Medicine, University of California, Davis, published in the Journal of Exotic Pet Medicine, has investigated potential risk and protective factors for the development of clinical urolithiasis in guinea pigs¹.

Online surveys of guinea pig owners were used to collect signalment, dietary and medical history for guinea pigs. The analysis included 70 guinea pigs with uroliths identified via imaging, surgery, or manual expulsion, and 172 guinea pigs that had never been diagnosed with clinical urolithiasis or other urinary tract disease. Prevalence, odds ratios and 95% confidence intervals were evaluated for 82 factors, including age, sex, reproductive status, and individual dietary items (i.e. percentage of pellets and hay, number of fruits/vegetables, and high-calcium dietary items), using unconditional univariate logistic regression analysis.

Guinea pigs older than 24 months were more likely to develop clinical urolithiasis than those less than 4 months of age. Unexpectedly, body weight was a significant protective factor, with animals weighing more than 1300 grams significantly less likely to develop uroliths than those weighing less than 1300 grams. Males were more likely to present for urolithiasis than females, regardless of reproductive status.

Guinea pigs given a greater variety of fruits/vegetables (7-10 types) were less likely to develop uroliths compared with those offered fewer types, which suggests that a diverse diet contributes to maintaining urinary tract health in guinea pigs. Increased fibre content in the diet was also found to be protective, as guinea pigs eating a higher percentage of hay had decreased odds of developing uroliths, while those eating a higher percentage of pellets had increased odds. Food items with higher moisture contents (>50%), such as bell peppers, tomatoes and romaine lettuce, were especially protective against the formation of uroliths, consistent with an American College of Veterinary Internal Medicine consensus statement for urolith prevention in cats and dogs. High calcium (≥50%) diets were associated with 0.76% higher odds of developing urolithiasis, however, this was not significant due to low case numbers. Vitamin C supplementation was not significant in protecting against the development of urolithiasis.

Limitations of the study include a relatively small sample size; the possibility that asymptomatic or subclinical urolithiasis cases may be represented within the control group due to the lack of medical records and imaging; or that using an online survey for the control population may have introduced selection bias.

Further research considering other potential factors, such as water intake and exercise, and with larger sample sizes and more rigorous control selection methods, would be beneficial.

Take home message

Age, body weight, sex and diet are important factors in the development of clinical urolithiasis in guinea pigs and should be considered when tailoring preventative strategies. Diets with a greater variety of fruits/vegetables, increased fibre content, and food items with higher moisture content are protective against the formation of uroliths.

Reference

¹Dadah HJ, Hawkins MG, Munk AW, Westropp JL, Kass PH & Beaufrere H (2025) Risk and Protective Factors Associated with Clinical Urolithiasis in Pet Guinea Pigs (Cavia porcellus). Journal of Exotic Pet Medicine. https://doi.org/10.1053/j.jepm.2025.07.005.