How do we measure a horse's quality of life?

An individual horse’s welfare depends on more than just having food, water and appropriate shelter. Their emotional well-being, or “quality of life”, is an important piece of the welfare puzzle. 

However, it is unclear what measurements are sufficiently accurate and reliable to help objectively assess this area of a horse’s welfare. A group of researchers from the United Kingdom, New Zealand and Australia have teamed up to address this.

The researchers completed two systematic reviews of studies in horses. One review focused on identifying equine behaviours that could reflect the horse’s mood and general well-being, - in other words, how they feel. The other review focused on physical measures of equine emotion, such as heart rate. The initial results of these reviews were presented on August 19, 2019 at the 15th annual International Society for Equitation Science (ISES) conference held at the University of Guelph.

Natalie Waran, from the Eastern Institute of Technology, New Zealand, presented on the findings related to equine behaviour. This review included 75 publications. Some of the behaviours they looked at included: feeding behaviour, types of interactions with humans and other horses (e.g. were they friendly or agonistic), and interest in the environment. They found that these types of everyday behaviours, and responses to training, were the clearest indicators of a horse’s emotional state. 

Waran adds “Examples of behaviours that indicated a positive emotional state were increased feeding behaviour, friendly social interactions (between horses and with humans) and interest in the environment. Examples of behaviours that indicated a negative emotional state were decreased feeding behaviour, negative social interactions, reduced interest in the environment and increased repetitive non-functional movement patterns”. 

She concludes that “these behaviours should help form the basis of assessment criteria so that horse owners and carers can assess and improve the quality of life of the animals under their care”.

Hayley Randle, from Charles Sturt University, Australia, presented on the results from the physical measures related to a horse’s emotion.  

Randle explains “Heart rate (HR), heart rate variability (HRV) and cortisol are the most commonly measured physiological indicators of equine emotion. Other suggested indicators include eye temperature, respiratory rate and salivary alpha amylase but many of these lack validation in relation to association with emotional state. There were methodological problems with all of the measures we looked at, such as the lack of standardisation of reporting and interpretation.” 

She concludes “The physical measures of equine emotion looked at in this review revealed that these may have limited use when assessing horse welfare.  A comprehensive set of measures that takes into account the horses experiences at any one time is needed to assess equine welfare and his/her overall quality of life.”

Kate Fenner, ISES council member, expanded on the importance of this presentation. “This research is an important step forward in equine welfare assessment”, she says, “We need studies like this that can help us identify consistent indicators of quality of life in order to build reliable welfare assessment tools that evaluate every domain of equine welfare.”  

For more details, see:

Indicators on the outside: Behaviour and equine Quality of Life

C. Hall, R. Kay, H. Randle, L. Preshaw, G. Pearson, N. Waran

Proceedings 15th Equitation Science Conference (2019) p54

Indicators on the inside: Physiology and equine Quality of Life

H. Randle, C. Henshall, C. Hall, G. Pearson, L. Preshaw, N. Waran

Proceedings 15^th Equitation Science Conference (2019) p55

The Proceedings are available:

https://equitationscience.com/previous-conferences/2019-15th-international-conference

Research identifies possible shock wave treatment markers

Extracorporeal shockwave therapy (ESWT) is used to promote healing of injured tendons and

ligaments. Using high-pressure sonic waves, ESWT is thought to increase blood flow to the treated area. It has been shown to reduce pain for several days after treatment.

This can cause problems if pain is masked before healing is complete. Overworked minor injuries could lead to major ones or even pose the risk of catastrophic life-threatening breakdown.

Competition authorities have introduced restrictions on horses participating after treatment. For example, the British Horseracing Authority banned the use of ESWT on the day of the race or on any of the preceding five days.

However, it’s one thing to restrict the use of ESWT; quite another to enforce a ban, as the therapy leaves no trace. That is, until now.

A team led by Mary Robinson, director of the University of Pennsylvania’s Equine Pharmacology Research Laboratory, and lab member Jinwen Chen has found that the practice does in fact leave a trail. In a paper in Equine Veterinary Journal, they report finding potential biomarkers of ESWT that, with further testing, could one day be used to enforce the ESWT ban.

"Because it's not a drug--it's applied to the surface of the skin--it's just not an easy thing to detect," says Robinson. "After a lot of trial and error, our study was able to measure changes in levels of five inflammatory factors, some of which we could detect up to three weeks after the shockwave therapy."

The search for these biomarkers dates back roughly a decade.

"It was Dr. Lawrence Soma, my predecessor, who said the lab was going to have to look at blood-based or urine-based biomarkers to try to detect shockwave therapy," Robinson notes.

To find the fingerprints that ESWT might leave behind, the researchers tested the therapy on 11 horses kept as a study herd at the University’s New Bolton Center. The researchers collected blood samples from the group of horses, composed of Thoroughbreds and Standardbreds, at several times both before and after each received a single dose of ESWT to a leg.

Over the years, the lab investigated various potential biomarkers - molecules that would indicate a horse received ESWT. They targeted 10 pro-inflammatory and anti-inflammatory signaling molecules, called cytokines, which they can measure from the blood using a sensitive test called ELISA, short for enzyme-linked immunosorbent assay.

"We looked a week before giving the shockwave therapy to see if there were any changes in the baseline period, due to changes in time of day or anything else, and didn't see anything we could define as significant," Robinson says. "And in the post-shockwave period we went out to three weeks."

No changes were detected in five of the cytokines they examined. But the other five-- TNF‐α, IL‐1β, IL‐1RA, IL‐6 and TLR2 – were significantly affected by EWST.

Of those, TNF‐α levels were significantly increased through the whole of the three-week post-therapy study period.

More study is necessary, Robinson emphasizes, before these biomarkers could be used to assess inappropriate use of ESWT in racehorses. For one, the researchers would like to see if measuring these same molecules in horses that are actively training and racing or that have an acute injury might change their results.

For that, she and her colleagues are actively pursuing follow-up studies to look at these biomarkers and other indicators using a biobank of samples from client-owned animals, including injured and active racehorses, treated at New Bolton Center.

The end goal is to keep the sport safe.

"Shockwave therapy is great as long as people rest the horse after using it," she says. "We are concerned that it's being abused in the racehorse industry and that it could potentially result in breakdowns. That's exactly what we're trying to avoid."

For more details, see:

Inflammatory mediators are potential biomarkers for extracorporeal shockwave therapy in horses

J.‐W. Chen, D. Stefanovski, J. Haughan, Z. Jiang, R. Boston, L. R. Soma, M. A. Robinson

Equine Vet J (2019)

https://doi.org/10.1111/evj.13183

New asthma research in horses finds possible link to latex

A study into the causes of severe equine asthma (sEA) has revealed associations with over 113 substances, including latex found in artificial surfaces.

Lead researcher Sam White found that natural rubber latex was among ‘the most surprising and significant’ of several new allergens present in the dust horses breathe.

The study used advanced computing power to assess 400 potential allergens in over 130 sEA-affected and healthy horses, working with research groups in Switzerland, France, Canada and USA.

The study revealed several previously suspected allergens, such as pollen, mould and insect proteins, are likely involved in sEA, but the most surprising finding was the implication that natural rubber latex might also play a role. In fact, four of the five most significant allergens associated with sEA were latex proteins. The fifth was a protein from Aspergillus fumigatus, a common fungus previously linked with sEA. Until now, latex had not been tested due to limitations associated with classical allergen assessment methods.

White, now based in Nottingham Trent University's School of Animal, Rural and Environmental Sciences, carried out the study for the Royal Agricultural University (RAU) and the University of Nottingham.

The research used mathematical modelling to allow diagnosis of sEA from a blood sample, avoiding the need for more invasive diagnostic techniques currently employed.

He said: “The most significant and surprising allergens associated with sEA were from natural rubber latex. Latex is historically associated with the equine environment in the form of artificial surfaces on arenas and racetracks.

 “The high level of respirable dust associated with training on these surfaces has already been linked with chronic bronchitis, inflammation and oxidative stress in riding instructors, and latex has long been associated with a variety of respiratory conditions in humans.

“These early results show it could be linked to respiratory problems in horses too, although it is too early to make a firm conclusion based on these data.” 

He added that further research is needed to establish the levels of latex horses are exposed to in their environment, and the effects it has on them.

White said the identification of new allergens would improve allergen avoidance and inform future diagnostic tests and therapies. 

 For more details, see:

Antigen array for serological diagnosis and novel allergen identification in severe equine asthma

S. J.White , M. Moore-Colyer, E. Marti, D. Hannant, V.Gerber, L. Coüetil, E.A. Richard, M. Alcocer

Sci Rep (2019) 9, 15170

doi:10.1038/s41598-019-51820-7