No attempt has been made so far to record the hospital incidence of obstructive urolithiasis in sheep under temperate agro climatic conditions of Kashmir valley. The present study on occurrence of obstructive urolithiasis in sheep appears to be the I
st attempt made in this regard. During the period from December 2014 to December 2015, a total of 225 ovine surgical cases were brought to the Veterinary Clinical Complex, F.V. Sc. and A.H., SKUAST-K for the treatment. Of these cases, a total of 61 cases were diagnosed with obstructive urolithiasis disease, thereby giving an overall incidence of 27.11%. All the cases were male rams with different age groups, weights and of different breeds. Clinical and ultrasonographic examinations were found sufficient to diagnose the cases of uolithiasis during this study, thus substantiating the findings of
Riedi et al., (2018). The incidence is very high as compared to that of large ruminants which accounts for only 15.79%
(Parrah et al., 2011). Sheep usually don’t receive individual attention; therefore there remains every chance of missing the diseased ones in big flocks. Moreover, there is a general notion among the local public and veterinarians that sick sheep is half dead. Sick sheep are usually disposed off in the local market without treating them. These conditions could be responsible for lower incidence of obstructive urolithiasis which otherwise would be very high.
Obstructive urolithiasis can occur in all the animals of every age and weight category and any sex. During the study, obstructive urolithiasis was observed only in intact male animals. The anatomical disposition of the male animals could be responsible for the uroliths lodgment and consequent development of obstructive urolithiasis. The lower urinary tract in male animals is long, tortuous and inflexible. Obstruction due to uroliths lodgment does not occur in females as their urethra is short with flexible lumen (
Larson 1996;
Radostitis et al., 2007). Castration affects the urethral development and testosterone production in the animals making the situation ideal for the uroliths lodgment. Reduction in the levels of testosterone decreases the hydrophilic colloids in the urine thus predisposing the animal to calculus formation (
Williams, 1955). Reduction in urethral diameter induced by castration predisposes the animals for urethral obstruction (
Larson, 1996). The disease is considered of high significance in fattening steers and in castrated lambs
(Radostitis et al., 2007). Very surprisingly, no male sheep suffering from obstructive urolithiasis recorded during the study was castrated.
The incidence of obstructive urolithiasis has been reported to be influenced by the season and period of the year. The harsh winter of Kashmir valley called locally as
Chilia Kalaan ranges from December 21st to ending February. This is a period when sheep and other animals develop uroliths because of excessive feeding of concentrates, lack of water and green fodders. The disease is then manifested mostly in the month of March. The results of the present study substantiate these view points as the highest number of the cases 27 (44.26%) were presented during the month of March (Table 1). Likewise, the highest (78.68%) incidence of ovine obstructive urolithiasis was recorded during winter season (Table 2). The finding of the study is in total consonance with that of
Amarpal et al., (2004), who also recorded higher incidence in ovine and caprine during extreme winter. Feeding of more concentrates, lower water consumption and deficiency of green fodder (vitamin A deficiency) are considered important contributing factors towards the development of disease
(Parrah et al., 2011). During winter animals are totally confined in their sheds with total concentrate feeding, no provision of green fodder and non-availability of luke warm water
ad lib. Feeding of concentrate induces antidiuretric hormone (ADH) release which causes a marked but transient decline in urine output and an increase in urine concentration (
Bailey 1981;
Hoffmeyer 1987). Concentrates are rich in phosphates content and may predispose the animals to urolithiasis (
Hay, 1990;
Larson 1996;
Van metre 2004). During summer, sheep are migrated to high land pastures for grazing green succulent forages. No concentrates are provided during this season. Water is provided
ad lib. Chance of uroliths formation during these conditions becomes very remote. Even transportation of a sick sheep from these pastures is impracticable. These could be the reasons that not a single case of ovine obstructive urolithiasis was recorded during summer.
The highest occurrence (31.14%) of the ovine obstructive urolithiasis cases was recorded in age group of 2-6 months and lowest in the age group of 26-30 months (3.27%) (Table 3). The incidence of the disease decreased with increase in the age of the lambs. It appears that the younger animals are unable to expel even the small calculi from the urethra ensuing in the urethral obstruction. The urethral diameter and strength of urethralis muscle are controlled by testosterone hormone, which is lower in the young males
(Radostitis et al., 2007). Findings of our study are also substantiated by the observations of
Videra and van Amstel (2016), who reported that male small ruminants were commonly affected because of their particular anatomy, which includes long, narrow, tortuous urethra with a thin urethral process. Findings of this study are also in consonance with those of
Mahajan et al., (2017), who also observed maximum number of cases in the age group of <6 months.
Cross Bred Kashmir Merino ovine were mostly affected, constituting (73.77%) followed by Cross Bred Corridale (18.03%) (Table 4). There appears no genetic predisposition to the formation of uroliths in animals. However, the Saanen breeds of sheep are reported to excrete high levels of phosphorus in urine thus making them apparently more susceptible to uroliths formation. The study area on and around VCC comprises the parts of district Ganderbal. As per the policy of Sheep Husbandry Department, J&K Government district Ganderbal has been exclusively earmarked for rearing of cross bred Kashmir Merino. The highest incidence of obstructive urolithiasis in this breed, thus commensurate with the highest population of the breed in that area. Perusal of the data again points towards another fact that cross bred animals are more affected with obstructive urolithiasis than local ones. This observation justifies the findings of the previous researchers
(Parrah et al., 2011), also recorded highest number of obstructive urolithiasis in cross bred calves than local ones in the same study area.
Highest number of ovine obstructive urolithiasis cases (60.65%) were brought for treatment at 48-96 hours after the onset of disease and lowest 4.91% at 96-120 hours (Table 5). Lack of definitive diagnostic facilities in the field like USG, vague symptoms exhibited by the urolithiasis cases, attempts to treat the cases with medicines at initial stages, non- availability of trained veterinarians to handle the cases and to give proper advice to the owners for referral of the cases to university clinics and other adjoining polyclinics and lack of transportation causes the delay in bringing the animals to the VCC for treatment. This is why the highest (60.65%) cases were brought to the clinics 48-96 hours after the onset of the disease. However, a good percentage of cases (21.31%) were brought to the clinics for treatment purposes during the initial stages of the disease (24-48 hours). The cases from far flung areas and hilly terrain were usually received as late as 120-144 hours of illness, when the cases were considered difficult to be treated locally. Contrast observations have been reported in other studies, where, maximum number of cases were presented in early phase of the disease (
Tiruneh, 2000;
Riedi et al., 2018).
At the time of admission, urinary bladder was found intact in majority of the cases 38 (62.29%) and ruptured only in 23 (37.70%) (Table 6). Complete obstruction to the urinary flow in the animals usually results in the rupture of either urinary bladder or urethra. During this study, no case with urethral rupture was recorded. Rupture in urinary bladder was found in most of the cases 23 (37.7%). Complete obstruction to the urine flow, delayed presentation of the cases for treatment and inadvertent administration of diuretics could be the cause of rupture of urinary bladder
(Parrah et al., 2011).
A mixture of feeds and fodders were given to ovines depending upon the season and availability of feed and fodder (Table 6). Mixture of rice bran, maize fodder and crushed maize formed the feeding schedule 1, being provided to the highest number of cases and combination of rice bran and tree leaves formed schedule 6 being provided to the least number of animals. Several risk factors predispose the formation of uroliths in ruminants, chief among which diet plays a significant role
(Jones et al., 2009), with concentrates reported to be always associated with urolithiasis (
Mathews, 2009). Season, feed and water intake have direct relationship with one another. During summer, sheep are fed exclusively on grazing pastures with no provision of concentrates but plenty of water available to take
ad lib. During harsh winter sheep are usually fed on concentrates with little forages and limited quantity of water. Feeding of concentrate instead of roughage diets results in reduction of water intake, reduced urine volume (
Hay, 1990), induces ADH release causing decline urine output (
Bailey, 1981;
Hoffmeyer, 1987). Low water intake, both direct as well as indirect results in super saturation of urine. Low urine production allows the concentrated urine to stay longer in urinary bladder and thus provides time for the crystallization of minerals that otherwise could have been flushed out
(Parrah et al., 2011).
