Photo of CEH quarantine rosebushes

The Center for Equine Health at UC Davis serves as the U.S. Department of Agriculture's California CEM Quarantine and Treatment Station.  Our facility is located on the southeastern edge of the UC Davis campus.  We are proud of our standing as a quarantine facility that has not released a positive animal throughout our 33-year history.

What is CEM and why do we test for it?

Contagious equine metritis (CEM) is a venereal disease of horses caused by the bacteria Taylorella equigenitalis.  It is spread during breeding or through infective semen (AI) or by contact with contaminated objects such as instruments or hands.  This disease occurs very rarely in the United States and does not affect other livestock or people.  However, it is highly contagious among horses and can be difficult to detect and control.  Signs of illness in infected mares may not be obvious or they may have a thin, grayish-white vulvar discharge about 10 days after breeding to an infected (carrier) stallion.  Stallions may carry the bacteria without showing any signs at all.  CEM can have a negative impact on fertility in both mares and stallions.

Federal Quarantine Procedure

Mares and stallions (not geldings or horses under the age of 24 months) arriving in the United States at one of four ports of entry (Los Angeles, CA; Newburg, NY; Miami, FL; and Honolulu, HI) have been tested for CEM already in their country of origin.  They are further tested at the port of entry for equine infectious anemia, dourine, glanders, and equine piroplasmosis.  If the results are satisfactory, the horses are transported under seal to UC Davis; that is, after the completion of required testing, the horse is led into the transport trailer and a USDA agent places a numbered metal band over the door lock.  Upon arrival at our CEM quarantine facility, the seal must be intact.