Blink of an eye: stress level indicator?

Equine behavioural studies often seek to assess the horse’s stress response to various stimuli. Physiological methods such as heart rate, heart rate variability, salivary cortisol concentration all have their place, but for some purposes a more hands-off approach might be preferable.

A study at the University of Guelph, Ontario, Canada looked at the correlation of eyelid movements with heart rate and behaviour. The full report is published in Animals (Basel).

Dr Katrina Merkies and colleagues studied the response of 33 horses to three stressful situations: being separated from their herd mates; not being fed at their normal feeding time; and being startled by a novel object. The responses were compared with those of the horses in their normal paddock environment.

To assess the horse’s response, the researchers monitored heart rate, and counted the number of eye blinks and eyelid twitches. (Each three-minute trial was recorded on video.)

They found that feed restriction was the most stressful situation. Horses showed increased heart rate, restless behaviour and high head position. The horses also blinked less often and had an increased frequency of eyelid twitches, compared with the normal (control) environment.

Neither the novel object test, nor the separation from herd mates test, produced an increase in eyelid twitches or heart rate, which suggests that the horses did not find these too stressful.

The authors conclude that “observation of eye blinks and eyelid twitches can provide important information on the stress level of horses, with a decrease in eye blinks and an increase in eyelid twitches in stressful environments.”

For more details, see:

Eye Blink Rates and Eyelid Twitches as a Non-Invasive Measure of Stress in the Domestic Horse.

Merkies K, Ready C, Farkas L, Hodder A.

Animals (Basel). 2019 Aug 15;9(8). pii: E562.

doi:10.3390/ani9080562

Free access to gait analysis articles.

Historically, assessing the severity of lameness has been a matter of opinion. The various gait analysis systems that are now available provide a more objective way of doing so.

Quantitative gait analysis involves the use of electronic sensors, enabling the assignment of numerical values to motion, with the application of kinetics and kinematics.

Interest in gait analysis has grown;  it now has applications beyond the pure assessment of lameness. Gait analysis is being used to assess the value of new therapies and in scientific studies that have implications for horse health and welfare.

The exceptional capacity of the horse’s locomotor system largely led to its domestication as a working, sport and leisure animal. It has resulted in a continuing fascination with equine performance, whether physiologically in terms of footfall patterns in different gaits or pathologically, when locomotion may be impaired.

Articles on gait analysis that have been published in the Equine Veterinary Journal, have now been brought together in one place. This virtual collection will be free to view online for one year from 4^th  October 2019.

Topics covered include:

• Combined influence of expertise and fatigue on riding strategy and horse-rider coupling during the time course of endurance races
• Head and pelvic movement asymmetry during lungeing horses with symmetrical movement on the straight
• Does ‘hacking’ surface type affect equine forelimb foot placement, movement symmetry or hoof impact deceleration during ridden walk and trot exercise?

“We have now reached a stage in which technical developments have permitted the introduction of user-friendly quantitative gait analysis techniques in clinical practice,” says Professor René van Weeren, who jointly edited the collection with Dr. Constanza Gómez Álvarez. 

“Accuracy and reliability of these techniques have increased to improve our performance in the assessment and monitoring of equine locomotor performance. However, these developments also urge us to reconsider our position as clinicians and pose new challenges in terms of interpretation of the data that are generated.”

Professor Celia Marr, Editor of the EVJ said: “The breadth and substance of this research shows how far we have advanced with equine quantitative gait analysis. It has moved far beyond solely being a tool for objective lameness assessment and continues to develop as an exciting method for the support of equine welfare and performance.”

Dr. Constanza Gómez Álvarez added: “Today, objective, quantitative gait analysis in the horse has outgrown the laboratory and is infiltrating all horse-related activities.”

The virtual collection is available at:

https://onlinelibrary.wiley.com/doi/toc/10.1111/(ISSN)2042-3306.Practical_uses_of_quantitative_gait_analysis

Can intestinal micro-organisms warn of laminitis risk?

New research will examine the gut microbiome and try to identify changes that occur in horses with

pasture associated laminitis.

The gut microbiome (the mixture of microorganisms [such as bacteria and fungi] that live along the intestinal tract) is a topic of growing interest in both human and veterinary medicine. 

Changes in its composition have been associated with various diseases in human medicine. Could changes in the microbial populations or their metabolic activity, give an early indication of disease susceptibility?

PhD student, Ashley Ward, will be working with Dr Philippa Morrison and Professor Caroline Argo, from Scotland’s Rural College (SRUC) in conjunction with WALTHAM and the Rowett Institute (University of Aberdeen). 

The research is supported by funding from SPILLERS™, via the brand’s science arm THE WALTHAM™ Equine Studies Group.

The project will run over three and a half years and will build on existing work on the equine gut microbiome. The aim is to try and identify changes in the faecal microbiome patterns or urinary molecules (ie “biomarkers”) that could be used to predict a case of pasture-associated laminitis.

Clare Barfoot RNutr, the Research and Development Manager at SPILLERS™ said: “We are excited about Ashley’s appointment to help progress this new project. We hope it will improve our understanding of changes in the gut microbiome/urinary metabolome associated with pasture-associated laminitis and identify potential novel ways to intervene in its development.”

Ashley Ward added: “I am thrilled to be part of this project, which will allow me to utilise my laboratory experience, develop my skills in postgraduate research and, ultimately, produce work which will supplement our current understanding of laminitis. I am passionate about working to improve the outcome for horses and ponies that are likely to develop laminitis.”

Eventually, the researchers hope the work will improve animal welfare by allowing for timely preventative interventions.

Read more about SPILLERS’ important research work:

https://www.spillers-feeds.com/blog/