No abstract

Path analysis was used to model the direct and indirect relationships among age, previous lactation yield or estimated transmitting ability for milk, body weight, days dry, reproductive disorders, milk fever, mastitis, reproductive performance, current milk yield, and culling. Prospective data were from 784 primiparous and 2,066 multiparous Holstein lactations from 33 herds. Heifers that were older, of lighter weight, or who had lower estimated transmitting ability for milk had more problems, less milk, and poorer survival. Dystocia in heifers had several detrimental consequences including 2.9 to 4 times more retained placenta, metritis, and culling and +7.4 d more to first service. Cystic ovaries were associated directly with 376 kg greater milk yield and with a 16.5-d delay in first service. Failure to conceive at first service and mastitis increased risk of culling 5.2 to 10 times. In multiparous cows, milk fever increased risk of reproductive disorders by 1.6 to 4.2 times and indirectly contributed to poor breeding performance and increased culling. Risk of culling was increased 2.1 to 3.7 times directly by mastitis and dystocia and by poor breeding performance.

No abstract

Borrelia burgdorferi, the etiologic agent of Lyme disease is a tick born spirochetal infection. Clinical signs of Lyme borreliosis are uncommon in horses, but when present they are often vague and nonspecific. In horses, Lyme borreliosis has been implicated in musculoskeletal, neurological, reproductive, and ocular disorders, including uveitis, but definitive diagnosis can be challenging as the causative agent is rarely isolated and serologic tests can be unreliable and do not confirm active disease. Here, we report two cases of equine uveitis associated with B. burgdorferi based on the identification of spirochetes within ocular fluids and confirmed with PCR testing. The two cases illustrate some of the challenges encountered in the recognition and diagnosis of equine Lyme borreliosis. Although only one of many possible causes of equine uveitis, Lyme disease should be considered a differential diagnosis, especially in endemic areas. Given the possibility for false negative results of serum tests during uveitis associated with B. burgdorferi and the failure of such tests to confirm active infection, a combination of cytologic assessment, antibody, and/or PCR testing of ocular fluids may be worthwhile if the clinical suspicion for Lyme uveitis is high.