Age, breed and seasonal patterns in the occurrence of ten dairy cow diseases: a case control study.

A total of 5,990 occurences of the diseases abomasal displacement, cystic graafian follicles, endometritis, hypocalcemia, ketosis, mastitis, metritis, ovarian hypofuction, pyometra and retained placenta were included in a case control study. The study was based on a hospital population of Holstein, Ayrshire, Guernsey and Jersey cows who were at least two years of age. The data were retrieved from computer storage of material abstracted for the Veterinary Medical Data Program. The transcription of data from original case records to these abstracts was examined as a source of error. An attempt was made to define each of the diseases by reference to random samples of the clinical records. Using the log-odds method, trends were noted for the youngest cows to be at increased risk of the reproductive diseases and for the Guernsey cows to be at increased risk of the uterine diseases. There was a tendency for peaks in disease occurrences in the winter (as opposed to summer) months.