Seroprevalence of an Endometriotropic Bovine Herpes Virus-4 in a Georgia Dairy
DOI:
https://doi.org/10.21423/aabppro20025057Keywords:
postparturient dairy cows, metritis, economic losses, endometritisAbstract
The University of Georgia Veterinary Diagnostic Laboratory has now confirmed more than 60 cases of suppurative, ulcerative endometritis associated with Bovine Herpesvirus-4 (BHV-4) in postparturient dairy cows. These cases have a clinical pattern of metritis that occurs 3 to 28 days postpartum. Beginning at 3 to 7 days postpartum, the uterus is characterized by necrotic, ulcerated endometrial mucosa with only mild inflammation in the lamina propria and submucosa. Over the ensuing 21 days, the ulcers become confluent/diffuse and epithelium is replaced by fibrinonecrotic, suppurative mats resulting in severe bacterial pyometra by day 24, usually involving Arcanobacterium pyogenes or Escherichia coli. In addition to the gross pathology, histopathologic evidence demonstrates viral inclusion bodies and virus detection techniques yield positive results for BHV-4.3 Before 1999, BHV-4-associated endometritis had rarely been recognized in the United States,4 but a syndrome of epizootic metritis similar in timing, course and outcome attributed to BHV-4 was reported in Europe in the 1980s.1,2,6 Significant seroconversion to BHV-4 occurs in affected herds. The viral sequence of this endometriotropic strain of BHV-4 differs from the BHV-4 strain that is associated with mild respiratory disease (DN599).3 Herds affected by this endometriotropic strain of BHV-4 have experienced high morbidity and mortality rates.3 One endemic dairy herd had a period mortality rate of 70% due to BHV-4- associated metritis (7 of 10 dead in one two-week interval). Due to concurrent or subsequent bacterial metritis associated with this viral infection, large economic losses are incurred from death, delayed breeding and infertility, discarded milk from antibiotic therapy, and decreased milk production from systemic effects of the metritis. Similar reports from other diagnostic laboratories indicate BHV-4 appears to be an emerging cause of endometritis in cattle throughout the southern and midwestern United States.