Clinical and epidemiological assessment of obstructive urolithiasis in buffalo calves

Introduction

Obstructive urolithiasis is an important urinary tract disorder of male buffalo calves and is characterized by the formation of urinary calculi that interfere with normal urine outflow, resulting in partial or complete obstruction of the urinary tract (Van Metre et al., 1996; Constable et al., 2016) [6,2] . The condition is frequently encountered in intensively reared buffalo calves and is associated with considerable economic losses owing to treatment costs, mortality, and reduced growth performance (Ewoldt, et al., 2006) [4] . In buffaloes, a hospital incidence of 12.66% has been documented (Singh et al., 2008) [9] . Urolithiasis is a significant urinary tract disorder with an overall incidence of approximately 5.04% in India. Among different animal species, the highest occurrence has been reported in goats (49.83%), followed by cattle (32.87%), dogs (14.53%), horses (1.38%), and sheep (1.04%), (Amarpal et al., 2004) [1] . Young buffalo calves between 3 and 12 months of age are particularly susceptible because they are commonly maintained under intensive feeding systems that utilize concentrate-rich rations containing cereal grains, wheat bran, and oilseed cakes (Singh et al., 2010; Makhdoomi et al., 2013) [9,5] . These feeds are characterized by high phosphorus concentrations and often result in an inverted calcium-to-phosphorus ratio, thereby predisposing animals to phosphatic urolith formation ( Van Metre et al., 1996) [6] . Male calves are affected more frequently than females because of the greater length, narrower diameter, and anatomical curvature of the male urethra. The distal sigmoid flexure and penile urethra represent the most common sites of obstruction due to their relatively narrow lumen (Rakestraw et al., 1995; Constable et al., 2016) [8,2] . Seasonal variation has also been reported, with a higher prevalence during winter months. Reduced water intake during cold weather may increase urine concentration and facilitate precipitation of urinary minerals (Van Metre et al., 1996) [6] . Phosphate-containing calculi, particularly struvite (magnesium ammonium phosphate) and calcium phosphate calculi, are commonly reported in concentrate-fed ruminants maintained under intensive production systems (Makhdoomi and Ghazi, 2013) [5] . Despite advances in diagnosis and surgical management, obstructive urolithiasis continues to be a major cause of morbidity in buffalo calves. Therefore, the present retrospective study was undertaken to evaluate the epidemiological characteristics, clinical findings, risk factors, and treatment outcomes of buffalo calves presented with urolithiasis during a six-month period.

Materials and Methods

Study design and case selection

A retrospective study was conducted using medical records of buffalo calves presented to the Referral Veterinary Polyclinic between November, 2025 and May, 2026. Cases diagnosed with obstructive urolithiasis based on history, clinical examination, ultrasonography, catheterization findings, and surgical confirmation were included in the study.

Data collection

Information regarding age, sex, breed, feeding practices, season of occurrence, duration of illness, clinical signs, ultrasonographic findings, treatment methods, and outcomes was extracted from hospital records. Animals were categorized according to age: Less than 3 months, 3-9 months, 9-12 months, more than 12 months. Seasonal occurrence was categorized into winter, spring, and summer.

Statistical analysis

Data were analyzed using SPSS version 25.0. Descriptive statistics were used to calculate frequencies and percentages. Chi-square (χ²) analysis was employed to evaluate associations between feeding practices and occurrence of obstructive urolithiasis. Significance was considered at p < 0.05.

Result and Discussion

Overall occurrence and age distribution A total of 138 buffalo calves were diagnosed with obstructive urolithiasis during the six-month study period. All affected animals were males. Age-wise analysis (Table 1) revealed that calves between 3 and 6 months constituted the largest group with 48 cases (34.78%), followed by 6-9 months (42 cases; 30.43%). Together, calves between 3 and 9 months represented 65.21% (90/138) of all cases, indicating that rapidly growing calves receiving supplemental concentrate feeding were the most susceptible group. Only 12 calves (8.70%) were younger than 3 months, whereas 10 calves (7.25%) were older than 12 months. The predominance of young calves is consistent with earlier reports in buffalo calves, where intensive feeding during the post-weaning growth phase was considered an important predisposing factor. Similar age-related susceptibility has been reported by Singh et al. (2010) [9] and Makhdoomi et al. (2013) [5] , who observed that rapidly growing buffalo calves receiving concentrate-rich diets were more frequently affected than older animals.

Seasonal prevalence

Seasonal distribution (Table 2) showed a marked winter predominance. Seventy-two cases (52.17%) occurred during winter (November-February), compared with 38 cases (27.54%) in spring and 28 cases (20.29%) in summer. Thus, more than half of all cases were presented during the colder months. Reduced voluntary water intake during winter likely resulted in increased urine concentration and enhanced precipitation of urinary minerals, thereby favoring calculus formation. Similar seasonal trends have been described in bovine urolithiasis under intensive management systems (Van Metre et al., 1996) [6] . Seasonal variation in disease occurrence has also been observed, with a higher prevalence during winter months. This increased incidence may be associated with reduced water consumption and vitamin A deficiency resulting from limited availability of green fodder during this period (Radostits et al., 2000) [7] . Vitamin A plays a crucial role in maintaining the integrity of the urinary tract epithelium and regulating vitamin D metabolism. Conversely, increased exposure to sunlight and elevated vitamin D activity during summer may contribute to the development of urinary calculi by influencing mineral metabolism and urinary crystal formation.

Feeding practices and risk factors

Feeding history (Table 3) indicated that 98 of 138 calves (71.01%) were maintained on concentrate-rich rations containing wheat bran, calf starter, crushed cereal grains, and oilseed cakes. Mixed feeding was recorded in 30 calves (21.74%), whereas only 10 calves (7.25%) received predominantly roughage-based diets. Wheat bran is characteristically rich in phosphorus and, when fed excessively, may reduce the dietary calcium-to-phosphorus ratio below the recommended level for growing ruminants. Such an imbalance promotes phosphaturia and favors formation of phosphate-containing calculi, particularly struvite and calcium phosphate uroliths (Van Metre et al., 1996) [6] . Chi-square analysis (Table 7) demonstrated a highly significant association between concentrate-rich feeding and obstructive urolithiasis (χ² = 16.84, p = 0.00004), confirming the major role of nutritional management in disease occurrence. The significant association observed between concentrate feeding and occurrence of obstructive urolithiasis in the present study further supports the importance of nutritional factors in disease pathogenesis

Clinical findings

Clinical manifestations are summarized in Table 4. Stranguria was present in all 138 calves (100%), making it the most consistent diagnostic sign. Tenesmus was observed in 122 calves (88.41%), tail switching in 110 calves (79.71%), restlessness in 103 calves (74.64%), and abdominal distension in 87 calves (63.04%). Complete urine retention occurred in 74 calves (53.62%), while 59 calves (42.75%) showed varying degrees of depression and anorexia. These findings indicate progressive urethral obstruction leading initially to painful urination and later to bladder distension and systemic illness. Comparable clinical signs have been reported in buffalo calves with obstructive urolithiasis (Singh et al., 2010; Makhdoomi et al., 2013) [9,5] .

Site of urethral obstruction

As shown in Table 5, the distal sigmoid flexure was the most common site of obstruction, accounting for 64 cases (46.38%). Obstruction of the penile urethra was identified in 39 calves (28.26%), while 25 calves (18.12%) had calculi lodged near the ischial arch. Multiple obstruction sites were recorded in 10 calves (7.24%). The predominance of the distal sigmoid flexure reflects the anatomical narrowing and sharp curvature of this segment, which favors lodgment of even small calculi. Similar observations have been reported in bovine and buffalo urolithiasis (Rakestraw et al., 1995; Constable et al., 2016) [8,2] .

Treatment outcome

Treatment outcomes are presented in Table 6. Twenty-eight calves responded to medical management, of which 22 recovered (78.57%). Tube cystostomy was performed in 82 calves and achieved the highest success rate, with 72 recoveries (87.80%). Combined tube cystostomy and urethrotomy was required in 28 advanced cases, resulting in 22 recoveries (78.57%). Overall, 116 of 138 calves recovered, giving an overall survival rate of 84.06%. The superior outcome of tube cystostomy likely reflects restoration of urine flow while allowing time for urethral inflammation to resolve. Similar outcomes have been reported in previous studies where tube cystostomy effectively restored urine flow and facilitated urethral healing (Ewoldt et al., 2006; Makhdoomi et al., 2013 and Tamilmahan et al., 2014) [4,5,10] . Before surgical procedure, it is must to stabilise the animal as metabolic derangements like hyperkalemia, hyponatremia and hypocalcemia exists (Makhdoomi and Ghazi, 2013) [5] . This is generally been done by giving fluid therapy. Maintaining an appropriate calcium-to-phosphorus ratio, ensuring unrestricted access to water, and limiting excessive wheat bran supplementation may reduce disease incidence (Van Metre et al., 1996) [6] .

Conclusion

The present retrospective study demonstrated that obstructive urolithiasis is predominantly a disease of male buffalo calves between 3 and 9 months of age. Winter season, concentraterich feeding, and excessive use of wheat bran were important risk factors. The distal sigmoid flexure was the most common site of obstruction. Early diagnosis and prompt surgical intervention, particularly tube cystostomy, resulted in favorable treatment outcomes. Adoption of balanced mineral nutrition, adequate roughage supplementation, unrestricted access to clean water, and urinary acidification strategies may help reduce disease incidence.

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