Veterinarian injuries associated with bovine TB testing livestock in Michigan, 2001.

Testing all the cattle in an entire state with a uniform procedure for each animal affords an opportunity to relate human injury data to a known number of animals handled while carrying out a standardized procedure. Our objective was to describe the type and incidence density of injuries associated with TB-testing a large number of cattle herds, and to delineate the various factors associated with the risk of injury. A survey was mailed to all veterinarians (N = 259) who had completed at least five official bovine TB (bTB) herd tests in Michigan in 2001. We collected data regarding basic demographics and health status, work experience, veterinary specialty, and practice information. Each veterinarian was also requested to complete a separate injury questionnaire for each injury received while TB testing livestock in 2001. Accurate addresses were found for 247 eligible veterinarians, 175 (71%) of whom returned the survey. Thirty-six veterinarians reported a total of 53 injuries (10 major, 12 minor and 31 self-treated). Hands (29%) and legs (21%) were the anatomic locations most frequently injured, with sprains/strains (30%) and abrasion/contusion (30%) the most common types of injuries sustained. The overall incidence density of injuries was 1.9 per 10,000 animals tested. Female gender (RR = 3.3), being employed by the government (RR = 4.5), and smoking (RR = 6.0) were significantly associated with a higher rate of injury. Significant colliniearities were found between some risk factors associated with an increased rate of injury and participants thought 81% of their injuries could have been prevented. These results are explained by the administrative structure of the bTB testing program in Michigan, and the changing demographics of the veterinary workforce.

Recombinant bovine somatotropin: association with reproductive performance in dairy cows.

A clinical trial was performed to determine the effect of bST on reproductive performance in dairy cows on 4 Michigan dairy farms when bST was used according to labeled directions. Holstein cows (n = 555) at 4 Michigan dairy farms were randomly assigned to receive bovine somatotropin (bST) or to serve as untreated controls. Bovine somatotropin (500 mg, s.c.) was administered every 14 d beginning at 63 to 69 d of lactation and continuing until approximately 21 d prior to the end of lactation or until the producer removed the animal from the herd. A total of 229 (42.57%) animals consisting of 112 (48.91%) controls and 117 (51.09%) bST-treated cows were not diagnosed pregnant and were considered as having reproductive failure by 150 d of lactation and 92 (17.10%) of the animals consisting of 45 (48.91%) controls and 47 (51.09%) bST-treated cows had reproductive failure at the end of their lactation. No significant difference in the incidence of reproductive failure existed between the study treatment groups during either time frame. Cows with cystic ovarian disease had more instances of reproductive failure at 150 d of lactation than cows without this disease. Cows with dystocia, twin births, metritis, displaced abomasum and cystic ovarian disease had more instances of reproductive failure by the end of lactation than cows without these diseases. The bST-treated cows developed more nonspecific off feed conditions during the study lactation and had more twin births at the calving following bST administration compared to control cows. No differences were found between the study treatment groups in calculations of reproductive parameters. Logistic regression analysis found no significant effect of bST on reproductive failure; the odds ratios for the bST treatment effect on reproductive failure at 150 d of lactation and reproductive failure at the end of lactation were 0.95 (95% CI 0.67 to 1.36) and 0.95 (95% CI 0.59 to 1.54), respectively. Overall, bST was not found to have a significant impact on reproductive performance in the herds studied.

The role of epidemiology in public health.

Epidemiology is the study of disease in populations. Veterinarians and others involved in the preventive medicine and public health professions use epidemiological methods for disease surveillance, outbreak investigation, and observational studies to identify risk factors of zoonotic disease in both human and animal populations. Knowledge of these risk factors is used to direct further research investigation and to implement disease control measures. The use of hazard analysis critical control point (HACCP) systems depends greatly on information produced by epidemiological studies. Epidemiological methods are used for disease surveillance to identify which hazards are the most important. Epidemiological studies are also used to identify risk factors which may represent critical control points in the food production system.

Recombinant bovine somatotropin and clinical mastitis: incidence, discarded milk following therapy, and culling.

Holstein cows (n = 555) from four Michigan dairy farms were randomly assigned to receive bovine somatotropin (bST) or to serve as untreated controls. Bovine somatotropin (500 mg) was administered every 14 d beginning at 63 to 69 d of lactation and continuing until approximately 21 d prior to dry-off or until the cow was removed from the herd. Trial objectives were to determine the effect of bST on the incidence of clinical mastitis, number of days that milk was discarded because of therapy for clinical mastitis, and culling for mastitis. A total of 127 (22.9%) cases of clinical mastitis occurred during lactation. In the pretrial period (before 63 to 69 d of lactation), 42 (33.1%) cases occurred, and 85 (66.9%) cases occurred during the trial. Of the 42 pretrial cases, 57.1% occurred in control cows, and 42.9% occurred in treated cows. Of the 85 trial cases 47.1% occurred in control cows, and 52.9% occurred in treated cows. Using logistic regression, the odds ratio for the occurrence of clinical mastitis in treated cows was 1.06 (95% confidence interval = 0.62 to 1.81). The number of days that milk was discarded following therapy for clinical mastitis and the culling rate for mastitis did not differ between study groups.