Young burro with a floppy ear at Litchfield, showing tag number.

We have written a lot about post-capture deaths and wild burros. Most recently we informed you of the needless death of a baby burro born in a holding facility.

Post capture deaths in burros are higher than in wild horses. Burros are extremely susceptible to capture stress.

A new wave of post-capture deaths are hitting burros from the recent Canyonlands Roundup. 25 of the 85 captured have died of an illness under investigation.

An update from WHE burro team lead Laurie Ford

Canyonlands, 2025

It has been well documented that the immune systems of our wild burros have been weakened by the decrease in their gene pools as a result of fragmented habitats and excessive removals leaving non-viable breeding herds on the range. In addition, after roundups they are exposed to  new environments and an unnatural diet which can lead to inappetence – putting the burros into a negative energy state – which further diminishes their ability to fight off illness or new pathogens.

It is also well known that the combination of stress and capture, co-mingling, and relocation puts them at high risk of dormant infections being re-activated, such as the herpes virus, which can become complicated by secondary bacterial infections.

Scientific literature states: Herpesviruses are important pathogens associated with respiratory disease in equids.

The Bureau of Land Management is currently investigating the recent illness, and 25 deaths, of wild burros that were rounded up by helicopter between Feb. 24-28, 2025, from the Canyonlands HMA in southcentral Utah – an area famous for its sandstone formations.

After showing signs of lethargy and respiratory illness burros began to die with the first death occurring on March 11. Necropsy results identified the cause of deaths as bronchopneumonia, complicated by a secondary infection with the Streptococcus equi ssp. Zooepidemicus bacterium.

The underlying viral infection causing the deaths was identified as a gammaherpes virus – the same herpesvirus that was detected in the 2016 Sinbad burro deaths.

Bacterial cultures taken from some 2016 deceased Sinbad burros also found Streptococcus present.

Sinbad

In 2016, 103 burros were removed from the Sinbad HMA in Utah – an area in close proximity to Canyonlands – where sandstone also dominates the terrain which, when disturbed, disperses toxic silica dust that can damage lung tissues and worsen over time.

According to a Journal of Veterinarian Diagnostic Investigation (2021) The stress of capture along with exposure to pulmonary irritants such as dust or ammonia may contribute to the development of pulmonary fibrosis.

Within a few months 25 burros – 19% of those removed – had died “from a variety of causes” according to BLM. 

It was determined that the deaths were related to a chronic viral pneumonia characterized by pulmonary fibrosis (a lung disease that can result in lung scarring, interfering with an animal’s ability to breathe), and that an uncommon Asinine herpes virus had been tentatively identified.

Sinbad

Donkeys, like horses, are obligate nasal breathers, meaning they primarily breathe through their noses and do not breathe through their mouths. This anatomical characteristic, while beneficial for scent detection and feeding, can lead to respiratory problems if the nasal passages become obstructed or inflamed, causing difficulty breathing. In basic terms: Burros normally breathe through their nostrils, but can also breath through their mouths if there is an obstruction or other situation – typically during times of increased physical exertion to increase their oxygen intake- but less efficiently. Because burros are considered to be “nonathletic” – their instinct is to freeze rather than take flight during times of uncertainty – roundups force them to unnaturally overexert themselves.   

In normal donkeys, respiratory rate ranges from 12 to 28 breaths per minute. The average is 20 breaths per minute. Under extreme stress this rate rises to around 50. It can take a donkey an hour to return to normal breathing post stress. Donkeys are extremely hardy, but they are not aerobic athletes.

Compare to a healthy horse that has a resting respiratory rate around 8-12 breaths per minute. During exercise or when stressed (like running from a helicopter or winning the Kentucky Derby), a horse’s breathing rate can increase significantly, potentially reaching as high as 120 breaths per minute. After exertion, a healthy horse that has not been overstressed, healthy respiration rates return to 8-12 breaths per minute. (This is why “settle time” and really monitoring respiration rates before loading at trap is so extremely important. If normal respiration is not returning for any member of the band, young or old, the pilot is pushing too hard.)

Marietta, 2024

Given that herpesviruses are characterized by latency, with reactivation and shedding at times of stress and debilitation, it is likely that the virus was present in the feral herd with several persistently infected animals at the time of the roundup. The stress of capture along with concurrent disease such as parasitism, bacterial pneumonia in some cases, or exposure to pulmonary irritants such as dust or ammonia, may have caused reactivation of the virus, thus contributing to the development of pulmonary fibrosis. (Detection of asinine gammaherpesviruses in association with pulmonary fibrosis in free-ranging donkeys)

In 2020 the study, A Pilot Serosurvey for Selected Pathogens in Feral Donkeys, concluded: Given the fact that donkeys in the wild tend to remain in pairs or very small groups and that they often live in vast arid landscapes, the findings in this study may be applicable to feral donkeys in similar locations. The apparently naïve nature of these donkeys to common pathogens supports the need for exceptional care and biosecurity measures upon removing wild equids from their native habitat. Transportation vehicles and holding pens should be appropriately cleaned prior to movement in order to minimize risk of exposure to common equine pathogens. Further work is needed to understand the incidence of clinical disease from these pathogens in these populations upon removal from the wild, and co-mingling, in order to determine the optimal vaccination recommendations.

In our work at WHE at roundups we often document very poor cleaning of trailers during capture operations and holding pens can go weeks without cleaning. After transport to a holding facility the damage caused by poor bio-security during trapping has already been done even before all captives are placed in the same pens.

Canyonlands, 2025

In May 2022, 152 more burros were rounded up from the Sinbad HMA (UT). 13.8% were dead within 40 days. Twenty-five percent of pregnant jennies captured died citing “foaling complications” while noting hyperlipidemia in the death notes.

April 2025: Of the 85 wild burros captured during the 2025 roundup of Canyonlands (UT), 25 burros died due to the illness currently under investigation. 

We will update you as we know more.

Concise and enforceable welfare rules are long overdue. 

Basic veterinary knowledge and practices are absent from the BLM standards currently employed through the CAWP. Important standards involving air quality and heat indexes are dismissed by BLM today. Recognizing burros are not horses seems to also evade the agency as they rush to remove as many wild horses and burros as possible to reach a nontransparent and nonscientific quota.

Please join us in calling on Congress to designate funding to complete formalization of a welfare policy. in 2015, after years of litigation, BLM created a draft that was supposed to go through a review phase and then out for comment and formalization. In 2020, instead of giving the public a chance to provide desperately needed comments, they simply typed the word “permanent” and maintained the status quo.

Learn more and join us HERE. 

We need your support to keep our teams running. On range, through capture and into holding, our team is ready to go the distance to protect and preserve our precious wild ones. Thank you so much for standing with us!