UConn study links poor coat condition to higher parasite loads

A student works with a horse in the UConn stables
(c) Jason Sheldon / UConn)

Poor coat condition in horses has long been associated with heavy parasite burdens. A new
study from the University of Connecticut provides fresh evidence supporting this link and introduces a new tool to help assess it.

Led by Associate Professor Jenifer Nadeau in UConn’s Department of Animal Science, researchers developed a skin and coat condition scoring system to evaluate horses alongside their parasite levels. The work, published in the Journal of Equine Veterinary Science, builds on ideas that suggest that outward appearance may reflect an animal’s parasite resistance.

In the study, UConn’s herd of Morgan and Thoroughbred horses was regularly evaluated by students as part of the university’s hands-on equine science program. Faecal egg counts were collected to measure strongyle parasite loads, while separate teams of students, blinded to those results, scored each horse’s skin and coat condition.

The findings showed a clear trend: horses with higher parasite loads were significantly less likely to have good hair lustre. Although factors such as breed, age, housing, and season also influenced coat condition, parasite burden remained a strong predictor. Thoroughbreds, for example, tended to score lower than Morgans across several skin and coat categories.

The new scoring system may provide horse owners, managers, and even animal control agencies with a practical tool to help identify horses struggling with parasite-related issues or neglect. It can complement existing faecal testing by offering a quick visual assessment that may signal when further investigation is needed.

Nadeau plans to continue investigating how parasite levels change throughout a horse’s life and how coat condition can be used as an additional indicator of health. The study reinforces a message well known to equine professionals: paying close attention to coat quality can provide valuable clues about what’s happening inside the horse.

For more details, see:

N. DeBel, J. Johnson, A. Simoneau, B. Sweeney, G. Stearns, M. Amalaradjou, E. Gibbs, T. Moore, J. Nadeau,

The effect of parasitic load on skin and hair coat condition in Morgan and Thoroughbred horses,

Journal of Equine Veterinary Science, (2025) Vol 148, 105546

 

https://doi.org/10.1016/j.jevs.2025.105546

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Horses Inside Out Conference

 There’s still time to get tickets for the Horses Inside Out Annual Conference. 

 Back this year at the Holywell Conference Center in Loughborough, it will be held on Saturday 18^th and Sunday 19^th February.  If you can’t be there in person, you can still attend virtually.

 

An array of expert speakers has been lined up for what promises to be an inspiring meeting. 

Topics to be covered include bitting, nutrition, training the equine brain, rider psychology, hindlimb lameness, hoof care, dental disease and more.

 

For all the details, go to: 

 

https://www.horsesinsideout.com/annual-conference-2023

Thoracic asymmetry in ridden horses

 Muscle asymmetry in the thoracic region has implications for saddle fitting. If the muscle on one side of the withers is more developed than the other, this will affect saddle fit, potentially causing pain and discomfort. 

A study, led by assistant professor Dr. Katrina Merkies, at the University of Guelph, Ontario, Canada looked at muscular symmetry at the withers. 

 

Undergraduate students in the Department of Animal Biosciences, Julia Alebrand, Bethany Harwood,  Katharine Labarge and Laura Scott conducted a retrospective study of  490 horses. They studied withers measurements, taken with a flexible withers tracing tool, that had been recorded by a saddle fitting company.

 

Horses of various breeds (from Arabs and Thoroughbreds to stocky Warmbloods and Drafts) and a range of disciplines (dressage, hunter/jumper, recreational pursuits) were included in the study.

 

They found that almost 60% of horses had more muscle on the left side. 

 

In this population of horses, wither measurements were not significantly affected by horse breed, age, sex, height or level of training. Rider age, gender, height, weight and level of training did not affect wither measurements either.

 

The work is reported in Comparative Exercise Physiology. The authors report that horses in their study were asymmetric in their thoracic structure with most being larger on their left side than the right. They suggest that this asymmetry may be due to genetics, environment, or training. Importantly, it should be considered when fitting a saddle to the horse.

 

For more details see:

 

Investigation into thoracic asymmetry in ridden horses

K. Merkies; J. Alebrand; B. Harwood; K. LaBarge; L. Scott.

Comparative Exercise Physiology (2020), Vol 16, 1, pp. 55-62(8)

https://doi.org/10.3920/CEP190025

 

To find out more about the study, watch a video interview with Dr. Merkies

https://www.youtube.com/watch?v=77bUmR0JUZU&t=3s

Evaluating English saddle fitting

Poorly fitted saddles can adversely affect welfare and impair performance of ridden horses. The Saddle Research Trust Research Workshop, held in December 2018, identified a need for improved education of saddle fit evaluation among professional equine practitioners.

An educational article was subsequently commissioned by the editor of the peer-reviewed scientific journal, Equine Veterinary Education, that would simplify the complex subject of saddle fitting evaluation.

The article aims to provide practical guidance to equine veterinarians to assist in their decision-making process whilst carrying out routine assessments when a horse is evaluated ridden, such as for pre-purchase, lameness or poor performance examinations. It also clarifies when a saddle may be contributing to pain and performance problems and when the veterinarian should refer the client to a saddle-fitting professional.

“Evaluating the suitability of an English saddle for a horse and rider combination”, a collaboration between Anne Bondi, Sue Dyson, Sue Norton and Lawrence Pearman, is a comprehensive mini manual aimed at vets and physiotherapists and which will be equally of interest to other professional equine practitioners.

Thanks to the generosity of the publishers, the article is free to view. Go to:

https://doi.org/10.1111/eve.13158

To rug or not?

Some horse owners routinely put rugs (blankets) on their horses all year round, however new research suggests that certain types of rug could be causing them to overheat.

It has become routine (and even fashionable) for many domestic horses to be rugged all year round – in fly-sheets, all-weather turnouts, stable rugs, fleeces or perhaps even a onesie. Rugs can be useful in protecting horses from biting insects and in adverse weather conditions, however until now there have been very few studies on rugging at all and none on the effect of different types of rugs on a horse’s body temperature.

Like humans, horses have a ‘thermoneutral zone’ (TNZ) – an optimal range of temperatures within which they can comfortably maintain their own body temperature. For adult horses in mild climates, this is between 5⁰C and 25⁰C. Humans, on the other hand, have a more limited TNZ of between 25⁰C – 30⁰C when naked. This means when humans feel cold, horses are still well within their comfortable zone. Humans often make decisions about rugging their horses based on whether they feel cold themselves, so they may well be using a rug on their horse when it really is not necessary.

Kim Hodgess, a MSc student from Duchy College, UK, carried out a pilot study to investigate how the use of different rugs affects horse temperature, and how this could impact horse welfare. She presented her findings at the 14th International Society of Equitation Science (ISES) conference in Rome in September.

The research team studied horses who were routinely rugged as part of their management routine, ten kept stabled indoors and two at pasture. Three of the horses wore sweet itch rugs (a sweet itch rug is a lightweight, non-waterproof rug that is used to protect the horse from biting insects and cover most of the horse’s body including the neck and belly), six wore fleeces, two wore light quilted rugs and two control horses were unrugged (one stabled and one at pasture).

The surface temperature of each horse was taken by taping a small temperature data logger directly on to each horse, just below the point of their hip. The environmental temperature was also recorded using temperature data loggers attached to either the horse’s stable door or to a wooden mounting block in the field. All temperatures were then recorded every minute for twenty-four hours.

The results showed significant differences between the temperature of the horses wearing different rugs.

Horses wearing sweet itch rugs had an average temperature increase of 4.2⁰C, those wearing fleeces 11.2⁰C and those wearing light quilted rugs had an average increase of 15.8⁰C.

 

The horses wearing fleece and light quilted rugs were found to have a significant increase in surface temperature. Four rugged horses had surface temperatures between 24⁰C–30⁰C, compared to the control horses at 12.5⁰C–18.5⁰C, when the environmental temperature had fallen below the TNZ to 4⁰C–4.5⁰C.

The researchers concluded that some types of rugs can significantly increase horse surface temperature beyond temperatures that are comfortable for the horse and could therefore compromise the horses’ capacity to regulate their own temperature.

While the use of rugs and blankets may be necessary for some horses, selecting the right type and weight of rug for your horse and his individual conditions is vital. Appropriate use and application must be seriously considered to ensure they do not have a detrimental impact on horse welfare.

Hodgess posed questions for further research: do dark coloured sweet itch rugs increase horse temperature, do rugs interfere with mutual grooming and can skin condition deteriorate with prolonged use of rugs?"

"Although this study found sweet itch rugs had no impact on thermoregulation,” she said, “I feel further research with a larger number of horses, in hotter weather conditions, with a mix of dark and light-coloured sweet itch rugs is required before we can be certain there are no negative impacts on equine welfare."

"I would like to continue this area of research, as I feel there is a lot more that could be investigated. A greater understanding of the impact rugs have on horse thermoregulation would help inform our rugging decisions, which has the potential to improve horse welfare."

For more details, see:

To rug or not to rug: potential impacts on equine welfare

K. Hodgess, S. Horseman and A.M. Walker

Proceedings International Society for Equitation Science (2018) p57

https://equitationscience.com/previous-conferences/2018-14th-international-conference

Are horses stressed when first bitted?

Many working horses exhibit expressions of mouth discomfort such as opening the mouth, grinding their teeth or crossing the jaw when a bit is used. These behaviours could indicate pain, or poor training.

Most performance horses are ‘bitted’, so the process of introducing the bit forms a key part of the foundation training for many horses. Investigating how to optimise this introduction could lead to benefits in performance and, in some instances, improvements in welfare.

New research has found that introducing the bit to a young horse for the first time can be a stressful process for them, although the horse may not show visible stress-related behaviours.

A student dissertation project from Nicole Bradley at the Bishop Burton College in East Yorkshire, UK, led by Caroline Benoist, PhD, set out to assess the stress response of previously unbitted young horses to traditional bitting techniques.  Researcher Rebecca Brassington presented their findings at the 14^th annual conference of the International Society for Equitation Science.

Eleven horses – seven geldings and four mares (average age 3.5 years) - were introduced to the bit using a traditional method, over three consecutive days.

The noseband and reins were removed from the bridles, leaving the bit attached to the head piece via the cheek pieces. The bits used were a mixture of single- and double-jointed loose ring snaffles.

In all cases the handler stood facing forwards on the horses’ left side and presented the bit, then placed their thumb in the left corner of the horse’s mouth to cause the mouth to open so the bit could be introduced. All horses remained tied up using a headcollar and lead rope over the bridle for the first minute after bitting. They were then let loose in their stable for five minutes.

The research team used several methods to assess each horse’s stress levels. An infrared thermographic camera was used to measure the temperature of each horse’s left eye. (Increases in eye temperature can indicate stress.) Thermographic images were taken immediately before bitting to establish the horse’s baseline, and then at 0, 1 and 5 minutes post-bitting.

The horses’ behaviour was observed and assessed for the first minute after bitting and their stress responses were graded on a 1-5 scale. Behaviours were assessed ranging from 1 (very relaxed: jaw and lower lip relaxed, no bit or mouth movement, soft/slightly closed eyes) to 5 (very anxious: mouth open for extended periods, opening/closing repetitively, teeth grinding, eye whites visible).

Heart rate values were also recorded using a heart rate monitor before, during and after the bitting process.

The researchers report that heart rates showed a significant increase between the baseline and all other timepoints on Days 1, 2 and 3.

However, no significant change was recorded in either eye temperature or observed behaviour after bitting over the three days. Neither were any differences identified between the two different bits.

The increase in heart rate during bitting significantly decreased over the three days as did the increase immediately after bitting. The horses showed less heart rate fluctuation on day 3 compared to day 1. Rebecca Brassington commented: “Collectively this provides indication of some habituation to the introduction of the bit during this short process.”

The heart rate changes showed that the introduction of a bit elicited a physiological stress response. However, the horses showed little indication in their observed behaviour that this was the case.

“No significant differences were recorded in the behaviour grade scale applied to the horses during 1 minute post-bitting despite the increased heart rate,” Brassington added, “indicating a variety of behaviours may be expressed with some individuals masking a stress response.

The researchers conclude that introducing the bit to a young horse can be stressfu, but they warn that relying just on the visible behaviour of the horse during the procedure may not give a true representation of the stress they are actually experiencing.

Horses do appear to become accustomed to the process when it is performed regularly, however the length of time needed for them to completely accept the bit is not yet known.

For more details, see:

Quantifying the stress response of horses bitted for the first time.

N.Bradley, R. Brassington, T. Bye and C. Benoist

Proceedings 14^th Conference International Society for Equitation Science. P28