Colorado State Veterinary Teaching Hospital Implements Precautionary Suspension of Elective Equine Admissions

Effective Oct. 31, elective equine admissions at the James L. Voss Veterinary Teaching Hospital at Colorado State University have been temporarily suspended as a precautionary measure to control risks related to equine herpes virus type 1, called EHV-1.

The suspension is in response to the late evening confirmation of EHV-1 affecting two horses at the hospital that were not initially being treated for the disease on Oct. 30. The virus, which is contagious through contact and through aerosols, can be controlled by restricting contact and with stringent decontamination of hospital facilities. The virus cannot be transmitted to humans.

"We believe that we can resume routine hospital activities within two weeks," said Dr. Martin Fettman, interim hospital director. "As an additional precaution, veterinarians from the hospital are contacting all owners of horses that could possibly have been exposed at the facility."

EHV-1 is closely related to the virus that causes cold sores in people. Research shows that all horses in the world are believed to be infected within the first year of life. Like a cold sore in humans, this virus stays in infected horses for life. Many, if not most, of these infections occur with only mild or no detectable symptoms.

The most common sign of infection is mild respiratory disease during the first two years of life. While extremely rare, infections can result in more severe complications such as abortions in pregnant mares or paralysis.

Horses under stress can transmit the virus to another horse because they "shed" the virus, or the virus becomes more active and infectious because of other, concurrent diseases.

A partially paralyzed horse was admitted into the hospital on Oct. 23. Following increased biosecurity precautions, this horse suspected of carrying EHV-1 was isolated while under treatment.

However, on Oct. 28, veterinarians at the teaching hospital recognized fever in two other horses. The fever was unrelated to their reasons for admission. Fever can be a symptom of EHV-1.

These two horses, which are currently being treated for EHV-1 infection, have displayed no other symptoms of the disease. No other horses at the hospital have exhibited any signs of infection. However, as a precaution, the hospital is testing all horses currently within its care.

Further diagnostic testing confirmed late on Oct. 30 that both horses were infected with EHV-1, said Dr. Paul Morley, director of biosecurity for the hospital. Upon receipt of the positive test results, the hospital was immediately closed to new equine patients.

"Our hospital has the most rigorous infection control program of any veterinary hospital in the world. We are very risk-averse and take more rigorous precautions because we want to ensure that our patients can receive the very best care available," said Dr. Morley. "While the risk of hospital-acquired infections can never be eliminated, we believe it is incumbent upon us to take appropriate precautions to minimize the potential for infection while patients are admitted to our hospital.  This is the reason that we have elected to temporally suspend equine admissions to our hospital."

"Be assured that our faculty and staff take the utmost precautions in caring for our patients," said Dr. Lance Perryman, dean of Colorado State’s College of Veterinary Medicine and Biomedical Sciences.  

The hospital has several staff members who are experts in EHV-1 treatment and mitigation, including Dr. Paul Lunn, professor and department head of Clinical Sciences at the college.  

"This is a very cautious move which shows the tremendous concern our clinicians have for their patients," said Lunn. "This precaution may be proven to be unwarranted, but horse-owners and referring veterinarians should be reassured by these intensive precautions."  

About 20 horses are currently admitted to the hospital. These horses will be monitored and isolated in the hospital until university veterinarians determine through testing that they no longer pose a risk to other horses that they contact.

"Our hospital routinely maintains stringent biosecurity and cleaning protocols, and we will take all necessary precautions to protect our patients," said Dr. Morley. "This is the unfortunate event that can rarely happen when treating horses with this condition."

"We will also be working closely with horse-owners and their veterinarians to ensure that their horses are protected," said Dr. Gary Baxter, head of the equine section and assistant department head.  

Other activities and services provided by the hospital and Colorado State College of Veterinary Medicine and Biomedical Sciences will be unaffected by these precautions. This includes activities at the Equine Reproduction Laboratory and the Equine Center which are at a separate facility three miles west of the teaching hospital, as well as ambulatory services for horses and other animals, and inpatient services for agricultural animals and small animals.

"People that are concerned about their horses’ health and disease associated with EHV-1 should contact their veterinarians," said Morley.

More information about EHV-1 will be also available online at