05/12/2026
Per Dr. Maggie Baldwin, State Veterinarian, on Friday, May 8, 2026:
Please see the notification below regarding the index case detection of Vesicular Stomatitis Virus (VSV) in a horse in Montezuma County, Colorado. At this time, we are asking for producers and livestock owners to monitor their livestock and contact their veterinarian if they notice any blisters/sores that may be VSV. It is also important to note that there may be movement restrictions in place for horses and livestock moving interstate and internationally. We will also be sending a press release out on Monday. We are currently working on updating the VSV webpage, so please be patient as we get some of those resources updated.
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Colleagues,
We are sharing an important update with you below regarding the index case of VSV in Colorado. Below we include important information for you on reporting suspect cases, sample collection and submission, as well as guidance on movement requirements.
We will maintain up-to-date information on our VSV Webpage, including updated guidance documents and case information. As always, if you have any questions, please reach out directly to our office.
~Dr. Maggie Baldwin
Vesicular Stomatitis Confirmed in Colorado
Colorado has become the second state in the country to have a confirmed case of vesicular stomatitis virus (VSV) this year. On May 7th, 2026, the USDA National Veterinary Services Laboratory (NVSL) reported positive test results on samples submitted from one horse in Montezuma County. The premises where the positive horse resides has been placed under quarantine. The horse was initially examined by the local accredited veterinarian who contacted the state after suspecting VSV. The area field Veterinary Medical Officer with CDA then completed a foreign animal disease investigation and samples were submitted to the USDA NVSL.
The positive horse is currently the only symptomatic animal among a small group of horses and cattle on the premises. Presenting clinical signs in the affected horse were lip and tongue lesions. Increased midge activity was noted by the owner in the week prior to the onset of symptoms. The premises is under state quarantine and will remain so until at least 14 days from the onset of lesions in the last affected animal on the premises.
Fifteen previous positive cases of vesicular stomatitis in 2025-26 have been diagnosed in multiple counties in Arizona since October 2025. Please see the USDA APHIS Veterinary Services VSV website to read the current situation report for all confirmed cases in the US.
What Veterinarians Need to Know
Report any cases that have clinical signs suggestive of VSV to the State Veterinarian’s Office at 303-869-9130. Reporting cases as quickly as possible will benefit your client and is the best way to reduce the negative implications to other owners.
NON-EQUINE CASES: All suspected VSV in non-equine cases (cattle, sheep, goats, pigs, camelids) must be investigated by state or federal animal health officials.
EQUINE CASES:
Hold Order: If you suspect VSV, in addition to reporting the case to the State Veterinarian’s Office, inform the owners that they are under a Hold Order which means that livestock cannot leave the premises until testing is done or the State Veterinarian releases the Hold Order. Once testing is completed, we will send a quarantine order to the owner if the samples test positive. Call our office if you have any questions on the restriction of livestock movement into and out of that facility.
Lab Submission: Now that the index case has been confirmed in Colorado, the Colorado State University Veterinary Diagnostic Laboratory (CSU VDL) in Fort Collins has been activated for VSV testing through the National Animal Health Laboratory Network (NAHLN). CSU VDL in Fort Collins will be able to receive and test samples for equine species only with VSV compatible clinical signs from accredited veterinarians.
• When you call to report the case to the State Veterinarian’s Office, you will be given a case investigation number that must be included on the lab submission form. Here is a link to the General Sample Submission Form. Check the box on page 2 for VSV testing and circle CF and PCR.
• Read the Sample Submission Process page for more detailed information about submitting samples.
• Keep samples refrigerated after collection and during transit to the laboratory. Ship samples using Priority Overnight shipping (First Overnight is very expensive and is not needed).
• Cost for PCR and CF testing is $125 ($55 for PCR, $70 for CF) per horse.
Sampling: When sampling a horse for vesicular stomatitis, you must obtain a minimum of two samples.
• Serum (for complement fixation antibody testing) - at least 2mL in a red top or other sterile tube. If possible, centrifuge the sample and separate serum from the clot (submit only the serum).
1. Note: CF test can be negatively impacted by red blood cell lysis so transporting the sample to the lab quickly or separating off serum is important
• Sterile swab (for PCR virus testing) - (Dacron/polyester with a plastic shaft) of lesions placed in a red top, screw-cap or other sterile tube with a maximum of 3mL TBTB media. Make sure the tube lid is secured so fluid does not leak out of the tube. Do not use wooden shafted swabs as they contain PCR inhibitors and cannot be accepted. If TBTB is unavailable, swabs can be placed in 1mL of sterile saline or other virus transport media as an alternative, although TBTB is preferred. Do not submit swabs in bacteriology culturettes.
• Additional samples to the swab may include:
1. Vesicular tissue (epithelium) placed in a screw-cap tube with no more than 3ml TBTB media or 1mL sterile saline
2. Vesicular fluid (from unruptured vesicles) placed in a screw-cap tube.
Supplies: TBTB media will be made available to accredited veterinarians for sample collection for Equine VSV cases. Please contact one of the following:
1. CDA Animal Health Laboratory
300 S Technology Ct, Broomfield, CO 80021
(303)869-9230
2. Colorado State University, Veterinary Diagnostic Laboratories
Fort Collins: 2450 Gillette Drive, Fort Collins, CO 80526
Ph. (970) 297-1281
Rocky Ford: 27847 Road 21, Rocky Ford, CO 81067
Grand Junction 3164 B1/2 Road, Grand Junction, CO 81504
3. The State or Federal field veterinarian in your area
Health Certificates
Colorado veterinarians and livestock owners should contact the state of destination when moving livestock interstate to ensure that all import requirements are met. States may impose certain restrictions for horses and livestock coming from VSV affected states, including a timed-CVI or additional requirements. Some states may also turn off the eeCVI function in Global Vet Link and may not allow equines to move on a trip permit. Always check with the state of destination prior to movement.
If the destination state requires you to certify that the livestock do not originate within a specified distance of a VSV-quarantined premises (for example a 10-mile circle), call our office at 303-869-9130. One of our staff can map the location of your client and the location of the nearest quarantine so you can ensure they meet the destination state requirements.
IMPORTANT: Canada restricts movement coming from VSV-affected states. Equine and livestock are not permitted to move from a VSV-affected state directly to Canada. Those equine and livestock must go to an unaffected state for a minimum of 21 days prior to being eligible for export to Canada.
Vesicular Stomatitis Virus Background
Vesicular Stomatitis is a viral disease that primarily affects horses and cattle and occasionally swine, sheep, goats, llamas, and alpacas. The transmission of VSV is not completely understood, but includes insect vectors such as black flies, sand flies, and biting midges. The incubation period ranges from 2-8 days. Clinical signs include vesicles, erosions, and sloughing of the skin on the muzzle, lips, tongue, ears, teats, sheath, or coronary bands. Often excessive salivation is the first sign of disease, along with a reluctance to eat or drink. Lameness associated with coronary band lesions or weight loss related to painful oral lesions and reluctance to eat may follow.
Some species of wildlife (e.g., deer and elk) may be susceptible to VSV. If you encounter a sick or deceased wild animal or have other wildlife-related questions, please contact your local Colorado Parks and Wildlife Office.
Humans may become infected when handling affected animals or contaminated fomites, but this is a rare event. To avoid human exposure, individuals should use protective clothing and gloves when handling affected animals and their equipment. Advise any symptomatic animal owners of affected premises to seek care and notify their healthcare provider of exposure to VSV. There are no routine tests or specific treatment for VSV in humans. VSV infection in humans is not reportable to public health unless infection in animals is also suspected and has not been reported to the State Animal Health Official.
Resources:
USDA APHIS Vesicular Stomatitis Factsheet
CDA Vesicular Stomatitis Information
Vesicular Stomatitis Guidelines for Shows and Fairs
Vesicular Stomatitis Guidelines for Veterinarians
Vesicular Stomatitis Guidelines for Horse Owners
Colorado Department of Agriculture | 305 Interlocken Pkwy | Broomfield, CO 80021 US
