Diagnosis of Milk Fever by a Water Hardness Test Kit in Ewes

The aim of the study was to evaluate the measurement of total calcium levels in sera of sheep with and without milk fever by using a commercial water hardness test kit. Thirty sheep with findings of milk fever from 9 different farms were used in the present study. Total serum calcium concentrations were determined by using a commercial water hardness test kit and a laboratory automated biochemical analyzer. Results of the test kit and laboratory methods were significantly (P < 0.001) correlated (Spearman’s p = 0.896). In conclusion, it has been determined that total calcium levels in sheep sera may be determined with a water hardness test kit as used in this study, and that data are in concordance with the clinical findings and the other laboratory results. INTRODUCTION Milk fever parturient paresis or hypocalcaemia is a metabolic disorder that occurs around the time of parturition or during early lactation in sheep (1). The disease commonly occurs in outbreaks, in groups of ewes exposed to forced exercise, long-distance transport, and sudden deprivation of food and grazing on oxalate-containing plants or green cereal crops (2). Although it is may be seen occasionally as epidemic in the herd where up to 25% of the herd may be affected, its course is mostly sporadic and generally affects less than 5% of the herd (1, 2, 3, 4). The disease is characterized by a low serum calcium (Ca) level (2, 5, 6). As a result of inadequate calcium intake during the last periods of pregnancy or first periods of lactation, the body may meet the required need of calcium through calcium mobilization from bones. If hormonal mechanisms are inadequate, for example in the case of an inactive parathyroid gland, mobilization is delayed and blood calcium concentration is reduced with the resultant development of milk fever. In small ruminants, hypocalcaemia may develop secondarily during the course of other periparturient diseases, particularly in pregnancy toxemia (7). The diagnosis of the disease is based on clinical or laboratory methods or based on the presence of risk factors which have been reported (8). Therefore, monitoring the calcium level in sheep during periparturient period may be useful for the identification of the development risk of both milk fever and other hypocalcaemia related periparturient diseases. The definitive diagnosis is made through measurement of total and /or ionized serum calcium concentration (7). Serum total or ionized calcium levels may be measured by laboratory and/or portable biochemical analyzers. In veterinary practice chemistry analyzers are often unavailable in the field. Therefore, the aim of the present study was to measure the total calcium levels in sheep sera with and without milk fever using a commercial water hardness test kit (wHTK) compared to a routine laboratory method. MATERIAL AND METHODS Animals Thirty ewes were used in this study had at least one clinical findings of milk fever such as depression, increased respiration, muscular tremor, weakness, sternal recumbence and extended or twisted head. Clinical examinations were made by the same veterinarian. The sheep were 3.3±1 years of age (range 2 and 5 years) were taken from 9 different farms. Fifteen sheep were pregnant and 15 sheep were lactating. Approximately 20 ml blood was collected from the jugular vein. Blood samples were allowed to clot for minimum 30 minutes at ambient temperature. The samples were then centrifuged and sera were collected. The sera were kept at -20°C until the analysis was performed. All samples were analyzed within 4 weeks. Serum calcium analyses Total serum calcium concentrations were determined by spectrophotometric method using an automatic biochemical analyzer (Cobas 6000 analyzer, Roche, Switzerland). All samples were analyzed at the same time. Based on the results obtained with the automatic chemical analyzer the values were found to be in the range of 6.1 to 10.1 mg/dl. Total calcium concentrations in the sera samples of all sheep were determined using a commercial wHTK which was designed for measurement of calcium carbonate concentrations in water samples (cHEMetrics. Inc Cat. No: K-1705. Calverton, VA, USA). The test was carried out as follows: Calcium in the test sample was allowed to react with a zinc salt in the presence of a color indicator. The determined blue and blue