b'AAEP FORUM ANGELA PELZEL-MCCLUSKEY, DVM, MSTheHorse.com/AAEP-ForumThe Return of Vesicular StomatitisA fter a more than three-year hia- might require them to test negative for VS tus, vesicular stomatitis (VS) hasfirst. Always contact the destination state returned to the southwestern andor country for transport requirements western United States. At the time of thisrelated to VS, as these can vary widely.writing (early August), more than 500Shows and events can also impose equine premises had been affected withmore stringent entry requirements dur-VS in Colorado, New Mexico, Oklahoma,ing a VS outbreak. Organizers might Texas, and Wyoming. We expect con- even cancel some events due to concern tinued spread within those states andover potential disease spread or reduced potentially others over the summer.attendance. Event participants must Vesicular stomatitis is a viral diseaseweigh the potential pitfalls of attending. COURTESY DR. ASHLEY SALINASthat primarily affects horses and cattle,If they are coming from an affected state, but it occasionally affects swine, sheep,they will need more stringent veterinary goats, llamas, and alpacas. People han- certification to get to the event. If the dling infected animals without properevent is being held in an affected state, biosecurity precautions can also contractthe out-of-state participants might have the virus and experience symptoms oftrouble getting back home after they fever, headache, muscle aches, and severeInfected horses develop vesicles (blisters) onattend. Additionally, outbreak situations fatigue. The virus is known to spreadthe muzzle, lips, tongue, ears, sheath, udder, orcan change in an instant; a county that naturally to livestock via black flies, sand coronary bands. wasnt affected today might become an flies, and biting midges, although other in- infected county tomorrow. You must sect vectors may also be involved in trans- as isolating lesioned animals away fromdecide whether to take the chance of mission. Clinical signs in infected horsesothers and implementing vector controltraveling during this time. include vesicles (blisters) on the muzzle,measures to reduce the likelihood ofAlthough there are many unanswered lips, tongue, ears, sheath, udder, or coro- continued spread.questions about how VS outbreaks occur, nary bands. These vesicles rupture afterMost VS-lesioned horses heal on theirwe know the virus circulates annually in a few days into crusty and oozing lesionsown with just some supportive care, butsouthern Mexico and Central America. from which the virus can further spreadolder horses or those with underlyingWe believe certain climatic factors, such by direct contact. The virus can alsomedical conditions might need more vet- as rainfall and temperature, favor VSV contaminate surfaces or objects. Sharederinary intervention, especially if they arevectors, and when these insects move water sources, buckets and feeders, salthaving difficulty eating or drinking.north along waterways they bring the licks, and other objects contaminated withIn addition to the lesions direct impactvirus into the U.S.saliva or discharge from the lesions canon horses and the hassle of associatedThe last VS outbreak in 2015-2016 was lead to ongoing disease spread.quarantines, interstate and internationalthe largest in recent history and resulted Veterinarians are required to reportmovement during a VS outbreak canin 823 infected premises in eight states suspected VS to state and federal animalbe fraught with challenges. Nearly all(Arizona, Colorado, Nebraska, New health officials. If they confirm theU.S. states enact interstate movementMexico, South Dakota, Texas, Utah, and disease, theyll place that property underrestrictions for animals traveling fromWyoming). While we dont yet know how state quarantine for at least 14 days fromVS-affected states during an outbreak.big this years outbreak will get, horse the onset of lesions in the last affectedThese often include requirements such asowners in historically affected states animal on the premises. This means ifhaving a recent certificate of veterinaryshould be aware of the current situa-new animals develop lesions, the quaran- inspection issued with specific statementstion and implement aggressive vector tine countdown restarts with each newattesting to the absence of VS lesions inmitigation and biosecurity strategies now case until no animals show clinical signsthe horse. Horses being transported in- to protect their horses throughout the of the disease. Property owners shouldternationally from the U.S. might not beoutbreak. Current situation reports are also practice disease mitigation strate- allowed to travel at all if coming from aavailable on the USDA-APHIS website at gies during the quarantine period, suchVS-affected state, or the receiving countrybit.ly/2yk9m19. hAmerican Association of Equine Practitioners, 4033 Iron Works Parkway, Lexington, KY40511859/233-0147www.aaep.org8September 2019The Horse | TheHorse.com'