The following was distributed to Colorado veterinarians by the Colorado State Veterinarian’s Office on February 2, 2021. Click here to sign up to receive immediate updates from the Colorado State Veterinarian’s Office.
The Colorado Departments of Agriculture and Public Health and Environment have confirmed that a mule residing in Eagle County has tested positive for bat variant rabies. This is the first case of rabies in domestic livestock in Colorado this year and the first case of rabies in an equine in Colorado since 2013.
The spillover of bat variant rabies into domestic animals and wildlife is less common than skunk variant rabies in Colorado but is still possible. This case illustrates the importance of vaccination for all domestic animals statewide and not only in areas where skunk variant rabies is established.
Case summary
The seven-year-old mule became acutely neurologic on Friday 01/15/2021 with clinical signs including weakness and ataxia. A veterinarian examined the mule on Monday 01/18/2021 and the animal continued to display signs including ataxia, inability to rise, cranial nerve deficits, and was borderline febrile. The mule did not have a history of receiving a rabies vaccine.
The veterinarian reported the case to the State Veterinarian’s Office, concerned about the potential for rabies, herpes, or any of the other equine neurologic reportable conditions. The mule’s condition continued to decline and it was euthanized on Thursday 01/21/2021. The veterinarian collected and submitted samples to the CSU VDL where it tested positive for rabies. The sample was forwarded to the CDC Rabies Laboratory where it was identified as bat variant rabies; additional sequencing is pending.
The area Veterinary Medical Officer completed a field investigation and placed the remaining livestock on the premises under quarantine.
The mule had come to Colorado from Arizona via Utah three to four months ago. Due to the prolonged incubation period and the unknown exposure history, the State Animal Health Officials and State Public Health Officials in Arizona and Utah were also notified of the diagnosis.
Information for veterinarians
Veterinarians are reminded that rabies should be on the differential list for any neurologic case with an unknown vaccine history. Veterinarians are required to report all equine neurologic cases to the State Veterinarian’s Office at 303-869-9130 or by contacting their area state or federal field veterinarian. If after hours, the office voicemail will indicate which staff veterinarian is on call.
Livestock vaccination
All species of livestock are susceptible to rabies; cattle and horses are the most frequently reported infected livestock species. All horses should be considered for vaccination against rabies. Rabies is considered one of the core equine vaccinations in the AAEP guidelines. Livestock that have frequent contact with humans (e.g. in petting zoos, fairs, and other public exhibitions) should be considered for vaccination against rabies, including species for which licensed vaccines are not available (extra-label use). Consideration should also be given to vaccinating livestock that are particularly valuable.
Resources
CDA rabies: https://ag.colorado.gov/animals/livestock-health/rabies
CDA reportable diseases: https://ag.colorado.gov/animals/livestock-health
CDPHE rabies: https://www.colorado.gov/pacific/cdphe/rabies
