Seventy-two captive tigers died across two tourist facilities in Chiang Mai, northern Thailand between February 8 and 19, in the largest mass fatality of tigers on record, after a co-infection of canine distemper virus and Mycoplasma bacteria swept through the animals with lethal speed, killing 45 tigers in a single 48-hour period at the crisis’s peak and eliminating nearly 30 per cent of the combined tiger population at both sites before disease control measures could slow the outbreak.
The outbreak began on February 8, when authorities were notified that 31 tigers at the Mae Taeng facility had appeared lethargic and begun falling ill. The first death was reported the following day. The most critical period came between February 12 and 13, when 45 tigers died within just two days across both sites, prompting emergency inter-agency meetings and a full quarantine response. By February 19, a total of 72 tigers had died, 21 at the Mae Rim facility and 51 at the Mae Taeng facility, both operated by Tiger Kingdom Co., Ltd.
Dr Peerapol Noinafai, Regional Livestock Officer 5, and Dr Anusorn Homkhachorn, Chiang Mai Provincial Livestock Officer, revealed that veterinary teams conducted pathological sampling from February 13 onwards. Laboratory analysis found no genetic material of avian influenza virus.
An early assumption that the outbreak may have originated from influenza A present in raw chicken feed supplied to the parks was eliminated by laboratory results. Instead, testing confirmed co-infection with canine distemper virus and Mycoplasma spp., bacteria associated with respiratory disease. Co-infection is believed to have led to severe pneumonia and complications, contributing to the high mortality rate.
Canine distemper is a highly contagious viral disease spread through direct contact with bodily secretions and airborne transmission, severely affecting the respiratory, digestive and nervous systems. Mycoplasma bacteria are transmitted by vectors such as ticks, fleas and stable flies, causing anaemia by destroying red blood cells. Stress from captivity and sudden weather changes were identified as contributing factors, with co-infection from both pathogens leading to more severe symptoms and higher mortality.
The speed at which the outbreak escalated was in part a product of the specific biological challenges involved in monitoring large captive felids. Some veterinarians in Chiang Mai urged a more detailed investigation before a final conclusion was announced, calling for comprehensive testing to rule out other diseases such as feline distemper. Somchuan Ratanamungklanon, Director-General of the Department of Livestock Development, told local media: “By the time we realised they were sick, it was already too late,” noting that detecting early signs of illness in tigers is significantly harder than in domestic cats or dogs, because large cats rarely display visible weakness until a disease has advanced to a serious stage.
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The disposal process for all tiger carcasses was completed as of Monday. Initially the carcasses were incinerated, but there were too few cremation facilities available and the process was later changed to burial. Each burial site was marked with the tiger’s identification number for any future reference. No skins or teeth were taken for sale. Disinfectants were applied following scientific protocols.
Surviving tigers were relocated for quarantine and care at a nursing centre in Mae Taeng district.
Authorities said investigations, including laboratory analysis, necropsies and epidemiological inquiries, are ongoing to determine the precise cause and risk factors behind the outbreak. As of the latest figures, 44 tigers remain at the Mae Rim facility and 130 at Mae Taeng. Vaccination of the surviving animals was being prepared.
Agencies responsible for disease investigation have not yet clarified where the pathogens originated, leading to public speculation about whether the outbreak may have come from shared food sources. The chief suspect remains the raw chicken meat supplied by a private farm and fed to tigers at both facilities. No definitive conclusion about the route of infection had been reached as of Tuesday.
Officials confirmed that canine distemper virus is not a zoonotic pathogen and poses no risk of transmission to humans. Staff working in the enclosures, including veterinarians and handlers, were placed under 21-day precautionary health observation.
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The deaths have prompted renewed international scrutiny of Thailand’s captive tiger tourism industry. Officials cited potential inbreeding in captive settings and the difficulty of detecting early symptoms as possible contributing factors, structural conditions that animal welfare organisations have long argued make captive petting facilities inherently high-risk environments for disease transmission and outbreak. Wildlife Friends Foundation Thailand said the deaths exposed the “extreme vulnerability of captive wildlife facilities to infectious disease.” PETA Asia said the tigers “died the way they lived, in misery, confinement and fear,” and called on tourists to stop visiting tiger petting attractions. The Tiger Kingdom Chiang Mai facilities had been popular with domestic and international visitors who paid to enter enclosures and interact with live tigers at close range.
The 2004 bird flu outbreak at a tiger zoo in Chonburi province, where nearly 150 tigers died or were euthanised, also involved raw chicken as the suspected vector, a precedent that gives the current investigation its most direct historical parallel, and that some virologists noted should have prompted wider adoption of cooked or processed feed protocols across Thailand’s captive tiger industry in the intervening two decades.
Tiger Kingdom Chiang Mai remained closed to the public as of Tuesday. No reopening date had been announced.