Blue light influence on PPID

Pituitary pars intermedia dysfunction (PPID) affects approximately 21% of the aged equine
population and is characterised by excessive hair growth, delayed shedding, and metabolic disturbances. While pergolide is the standard therapy, some horses continue to exhibit coat abnormalities and lethargy. Seasonal regulation of hair growth is photoperiod-dependent, and previous research has demonstrated that exposure to blue light can influence coat shedding. 

A study by Sinead Parmantier and colleagues in Ireland and Kentucky examined whether extending day length using blue light masks could enhance coat condition and reduce PPID-associated signs when used alongside medical management. A full report of the study is published in Animals.

Fifty-two horses (>15 years) with a veterinary diagnosis of PPID and visible hypertrichosis were recruited via an online owner survey.

The horses were assigned to treatment and control groups. The treatment group (n = 29) wore Equilume® blue light masks from mid-December, extending their daily photoperiod to 15 hours. The control group (n = 23) experienced the natural seasonal light–dark cycle. Because most of these horses (44 out of 52) were receiving daily pergolide medication for PPID, a second unmedicated control group (n = 17) comprising research horses in the USA was included. These horses were maintained under natural photoperiod conditions for the 13-month study period.

Hair length, shedding, and body condition were measured monthly. Owners of groups T and C1 completed bimonthly questionnaires on coat condition, fat coverage, energy, and other PPID symptoms. Data were analysed using linear mixed models and non-parametric tests to assess effects of time, group, and group × time interactions.

There was no difference in hair lengths between the blue-light-treated and the first control group, but the second control group had shorter hairs. Shedding started a month earlier in the spring for the blue light group. Owners’ questionnaires revealed better coat condition in April, reduced fat coverage in April and June, and more energy in February for the blue light group.

In a final assessment, treatment-group horses showed significant improvements in coat condition, PPID clinical signs, and perceived quality of life.

Although blue light treatment did not significantly alter overall hair length compared to medicated controls, it advanced shedding and improved clinical signs of PPID. 

These results align with previous findings that artificial photoperiod extension can influence hair follicle activity. Owner-reported outcomes indicate improved welfare, though the potential for observer bias warrants caution. The consistent positive trend suggests that blue light may act synergistically with pergolide, helping to mitigate coat-related symptoms and enhance comfort in PPID horses.

Extended photoperiod achieved via blue light masks advanced spring shedding and improved coat condition, energy, and perceived wellbeing in PPID horses. 

Blue light therapy shows promise as a complementary, non-invasive management strategy alongside conventional medication. Further controlled research is warranted to clarify the physiological mechanisms and optimise treatment protocols.

 

For more details, see:

Parmantier, Sinead, Panoraia Kyriazopoulou, Margaret McClendon, Amanda Adams, and Barbara A. Murphy. 

Influence of Extended Photoperiod Using Blue Light Masks on Hypertrichosis, Coat Condition and General Health Parameters in Horses with Pituitary Pars Intermedia Dysfunction" 

Animals (2025) 15, no. 19: 2905. 

https://doi.org/10.3390/ani15192905

Cardiology focus for latest EVJ virtual issue

Exercising ECG an important element of
cardiac assessment in sport horses. (EVJ)

 The latest Equine Veterinary Journal virtual issue brings together new research on equine
cardiac physiology, diagnostics, and management, with a focus on atrial fibrillation (AF). 

The collection, guest edited by Laura Nath and Vicky Savage, is free to read until 7 January 2026 and features 20 papers, including an editorial overview of current advances and ongoing challenges in equine cardiology.

Highlights include:

• Atrial fibrillation (AF): Recent progress in diagnosing and managing this common cause of poor performance in horses.

• Arrhythmia monitoring: Studies using implantable loop recorders and wearable ECG devices to detect AF and other rhythm disturbances during exercise.

• Exercise and heart rate: Links between peak heart rate, heart rate variability, fatigue, and the occurrence of arrhythmias—particularly in event horses during cross-country phases.

• Associated conditions: Connections between cardiac arrhythmias, upper respiratory obstructions, and exercise-induced pulmonary haemorrhage.

• Predicting AF recurrence: Use of atrial premature depolarisations and atrial fibrillatory rate to assess recurrence risk.

• Cardiac anatomy: Structural variations such as accessory valve leaflets that can influence imaging interpretation.

• Mapping and ablation techniques: Advances in 3D electro-anatomical mapping and ablation of arrhythmogenic tissue in standing horses, showing the feasibility of trans-septal approaches.

Laura Nath said the collection “improves our understanding of arrhythmogenic mechanisms and diagnostic approaches,” while Vicky Savage added that it “offers practical, evidence-based support to equine vets for diagnosing and managing cardiac disorders.”

For more details, see:

https://beva.onlinelibrary.wiley.com/doi/toc/10.1001/(ISSN)2042-3306.current-progress-in-equine-cardiology

Early-life management linked to racing success in Thoroughbreds, RVC study finds

(c) Tania Penderakis Dreamstime.com

Recent research conducted by the Royal Veterinary College (RVC) has shown that
Thoroughbred foals given extensive turnout in larger pastures during their first six months of life, and those weaned at an older age, are more likely to enter training, race more frequently, and earn greater prize money later in life.

The study provides new insight into how gestational and early-life management can influence the growth, development, and long-term athletic performance of racehorses. It aimed to enhance understanding of how early-life health and husbandry practices affect both racing outcomes and the financial sustainability of Thoroughbred breeding enterprises.

According to the research team, this is the first UK-based field study to comprehensively evaluate the effects of early-life exposures, particularly exercise and turnout, on later-life milestones and race performance in Thoroughbreds. The findings offer direct practical applications for stud farms, supporting both horse welfare and industry retention, in line with the Horse Welfare Board’s strategy for improving the welfare of racehorses.

The research, led by Dr Rebecca Mouncey, Post-Doctoral Research Fellow at the RVC, was conducted as a prospective cohort study. The team followed 129 flat-race bred Thoroughbred foals, born in 2019 and 2020 on six stud farms across the UK, from birth through to training and early racing careers.

Detailed data were collected on each dam’s reproductive history and health during pregnancy, alongside daily records of foal management, health status, turnout duration and area, and any veterinary-attended illnesses or injuries. These records were maintained until the foals left their stud farms or exited the study. Racing performance data were subsequently collated from industry databases up to the horses’ fourth year of life.

Statistical analyses, including mixed-effects logistic and linear regression models (with farm, mare, and stallion as random effects), were used to examine associations between gestational and early-life exposures and later racing performance.

Of the 129 horses studied, 76% (98/129) went on to race by the age of four, with a median of seven starts (interquartile range [IQR] 4–11) and median prize earnings of £6,898 (IQR £1,712–£17,987).

Significant associations were identified between early-life management factors and later performance:

• Turnout: Foals that spent more time turned out at pasture during their first six months of life were more likely to race and earned more prize money.
• Increasing average daily turnout time and pasture size were associated with higher odds of racing (Odds Ratio 1.31, 95% CI: 1.09–1.58, p = 0.004) and increased total prize earnings (β = 0.32 lnGBP, 95% CI: 0.03–0.61, p = 0.03).

• Weaning Age: Foals weaned later were more likely to race and made a greater number of race starts.
• Each additional day of age at weaning increased both the odds of racing (OR 1.03, 95% CI: 1.01–1.05, p < 0.05) and total number of runs (β = 0.09, 95% CI: 0.04–0.14, p < 0.05).

These results indicate that management during the first six months of life plays a critical role in preparing Thoroughbreds for future athletic success.

The findings demonstrate that early-life turnout and weaning practices significantly affect race participation, performance, and financial outcomes. Providing foals with ample turnout opportunities and delaying weaning until after this key developmental window may support positive musculoskeletal adaptation and improved future performance.

Dr Mouncey noted that: “This study is the first of its kind to evaluate the impact of early-life experiences on later racing performance in Thoroughbreds. Our findings highlight that the first six months of life represent a crucial developmental period in which management practices must promote optimal tissue development and welfare.”

The study was funded by the Horserace Betting Levy Board, the Racing Foundation, and the RVC’s Mellon Fund for Equine Research, and is published in the Equine Veterinary Journal.

For more details, see:

Mouncey R,  de Mestre AM,  Arango-Sabogal JC,  Verheyen KL.  

Born to run? Associations between gestational and early-life exposures and later-life performance outcomes in Thoroughbreds. 

Equine Vet J. (2025).

 https://doi.org/10.1111/evj.70084

Researchers seek horses for PPID treatment response study

  A research team from the University of Minnesota is urgently seeking horse owners and veterinarians to participate in a study on pituitary pars intermedia dysfunction (PPID), more commonly known as equine Cushing’s disease.

PPID affects up to 30% of older horses, causing a range of problems, from poor performance to severe illness and even death. The disease occurs when neurons in the hypothalamus are damaged, disrupting the brain’s ability to regulate the pars intermedia region of the pituitary gland. While there is no cure, treatment focuses on managing symptoms and slowing progression.

The most widely used treatment is pergolide which helps compensate for the dopamine loss seen in affected horses. Originally developed for Parkinson’s disease in humans, pergolide remains the only FDA-approved drug for PPID in horses.

However, horses vary widely in how they respond to this medication. Studies show that 60 - 80% of horses respond well, but definitions of “success” differ. Moreover, adverse effects are common. Anorexia is reported in up to 32% of treated horses, alongside issues like colic, weight loss, and behavioural changes. These side effects often lead owners or veterinarians to reduce or stop treatment, allowing the disease to worsen.

In human medicine, it is well established that genetic differences can influence how individuals respond to drugs. Researchers now believe the same may be true for horses.

To explore this, Dr. Molly McCue and Dr. Lauren Hughes of the UMN Equine Genetics and Genomics Laboratory, together with Dr. Dianne McFarlane at the University of Florida, are leading a study to identify genetic factors that influence pergolide response and side-effect risk in horses with PPID.

“Our goal is to identify genetic variants that influence treatment outcomes,” explain the researchers. “If we can find alleles that predict poor response or higher risk of adverse effects, we could tailor dosing and treatment to each horse, making therapy safer and more effective.”

Dr. Hughes adds, “As a veterinarian, I’ve seen how devastating PPID can be for horses and their owners. This research could help us greatly improve diagnosis, treatment, and management of this disease.”

The team is seeking horses diagnosed with PPID by a veterinarian - confirmed through bloodwork - who have been on pergolide therapy for at least six months. They are particularly interested in horses that:

·       Require higher or more frequent doses of pergolide

·       Experience adverse effects such as appetite loss, weight loss, colic, or behavioural changes

Eligible horses should:

·       Be 15 years or older at the time of diagnosis

·       Have clinical signs consistent with PPID (e.g. long, shaggy coat, muscle loss, dullness, or recurrent infections)

·       Have had follow-up blood tests (ACTH, TRH stimulation, or dexamethasone suppression tests)

Participation involves submitting medical records and providing hair root or blood samples. Owners may enrol as many horses as they wish.

The researchers emphasise that participation is vital: by contributing samples and data, owners will help uncover the genetic clues that could shape the future of personalised PPID treatment - offering hope for safer and more effective therapies for horses everywhere.

For more details, see: 

https://vetmed.umn.edu/equine/research/equine-genetics-and-genomics-laboratory/projects/equine-pituitary-pars-intermedia-dysfunction-ppid/pergolide-study

 

https://www.youtube.com/watch?v=kZl2WvUBt1w

Survey reveals challenges in managing equine obesity among UK horses

(c) Brian Sedgbear Dreamstime.com

 A recent survey of UK horse owners has provided new insight into the practical challenges surrounding equine weight management. While the majority of owners demonstrate a strong understanding of the causes of excess body condition, many report difficulties in putting effective strategies into practice. The findings underline the complexity of equine obesity, a major welfare concern linked to laminitis, insulin dysregulation, and equine metabolic syndrome (EMS).

The survey, conducted in summer 2025 by the SPILLERS™ brand, gathered 1,519 responses, with most horses reported falling in the 11–20 year age range. Strikingly, more than 74% of leisure horses were estimated by their owners to be overweight. In addition, 20% of respondents reported that their horse had been diagnosed with EMS, pituitary pars intermedia dysfunction (PPID, also known as Cushing’s disease), or laminitis – conditions strongly associated with excess body weight and metabolic disturbance.

Owners most frequently identified insufficient exercise (38%) and excess dietary calories (37%) as the leading causes of overweight horses. Age-related factors and underlying health conditions were also considered important (24%). These responses suggest that owners recognise the balance between energy intake and expenditure, yet still face significant barriers in applying this knowledge effectively.

Respondents demonstrated awareness of several recognised management techniques for restricting forage intake and controlling calorie consumption. The most commonly used methods included:

• Part-time stabling (19%) to reduce grazing opportunities.
• Small-holed haynets (18%) to slow forage consumption.
• Soaking hay (14%) to reduce water-soluble carbohydrate (WSC) content.
• Strip grazing (12%) to limit pasture intake.

Despite strong evidence that grazing muzzles can reduce grass intake by up to 80%, only 7% of owners reported currently using them. A further 52% had either never considered or had rejected the idea, often citing welfare concerns or lack of success. Of those who had used muzzles, roughly half reported positive results.

The use of straw as a partial forage replacer was less widespread. Only 18% of respondents had already incorporated straw into rations, while 24% were aware of the practice but had not yet trialled it. This suggests that although straw can help to increase dietary fibre intake without adding excessive calories, uncertainty remains among owners about its safe use.

When asked about the obstacles they faced, horse owners frequently cited:

• Lack of time to exercise their horse (22%).
• Difficulty controlling calorie intake (21%).
• Perception that the horse is “always hungry” (21%).

These findings reflect both the practical and emotional strain of managing equine weight. Several respondents reported feelings of guilt, frustration, and worry, highlighting that obesity management is not only a matter of feed and exercise, but also of owner wellbeing and motivation.

Most owners monitored body condition regularly, with 57% reporting daily or weekly checks. However, only 13% had access to a weighbridge, and 30% relied primarily on visual appraisal or photographs. While condition scoring and girth measurements are useful tools, the low uptake of objective weighing highlights an ongoing gap in precision monitoring.

When asked about feed features most valued for weight management, owners favoured low-calorie, high-fibre, nutritionally balanced products. Such formulations aim to support weight loss without compromising essential nutrient intake.

Many respondents also noted the value of online educational communities, such as the SPILLERS “Slimmers’ Club,” which at the time of the survey had more than 13,500 members. Members reported that the group provided encouragement, practical ideas, and reduced feelings of isolation in managing overweight horses.

This survey highlights several important points:

• Obesity remains highly prevalent among UK leisure horses, with major associated health risks.
• Owner knowledge is often ahead of practice, with barriers such as time, facilities, and horse behaviour preventing implementation of best practice.
• Grazing muzzles and forage replacers remain underutilised, despite good evidence of their value in weight management.
• Owner emotion and motivation are integral factors in successful weight management, and should be considered alongside veterinary and nutritional advice.
• Monitoring techniques need strengthening, with greater access to weighbridges and training in body condition scoring.

Could dietary supplementation with polyphenols help horses with equine asthma?

(c)Ankevanwyk Dreamstime.com

 Equine Asthma Syndrome (EAS) is a chronic, non-infectious respiratory disease of adult horses, characterised by airway inflammation, mucus accumulation, and variable airflow obstruction. Clinical signs range from coughing and nasal discharge to exercise intolerance and increased respiratory effort, particularly when horses are stabled or exposed to dusty environments. EAS is now recognised as a major cause of poor performance and reduced welfare in affected horses, with similarities to human asthma in both pathology and clinical presentation.

One area of interest in human medicine has been the potential anti-inflammatory effects of dietary polyphenols. Polyphenols are naturally occurring compounds found in plants, particularly in fruits, vegetables, tea, and herbs. They act as antioxidants and modulators of inflammatory pathways. In human asthma, certain polyphenols have been reported to reduce airway inflammation and improve lung function. Despite this promising background, their application in equine asthma had not been previously explored.

 

Researchers from the Department of Large Animal Medicine at the University of Georgia set out to investigate whether dietary polyphenol supplementation might offer similar benefits in horses with EAS. Their study aimed to evaluate the effects of a mixed polyphenol supplement on both systemic and pulmonary inflammation, as well as on bronchoalveolar lavage (BAL) cytology and clinical respiratory signs in healthy and asthmatic horses. The team hypothesised that polyphenol supplementation would decrease inflammation in both groups, and in asthmatic horses, would also lead to improvements in BAL cytology and respiratory signs.

 

The research was conducted in two parts.

 

Part One:
Eighteen horses were enrolled, including eight healthy horses and ten with asthma. Each horse received the polyphenol supplement daily for 6–8 weeks. Before and after supplementation, the researchers performed a thorough physical examination, collected BAL fluid, and measured cytokine concentrations in both serum and BAL fluid.

 

Findings: Horses with mild-to-moderate asthma showed improved BAL cytology after supplementation. In particular, the percentage of neutrophils (a marker of airway inflammation) decreased significantly in the asthmatic group. Levels of pro-inflammatory cytokines, including interleukin-6 (IL-6), also decreased after supplementation. Interestingly, interleukin-10 (IL-10), typically considered an anti-inflammatory cytokine, also showed a greater reduction in asthmatic horses compared with healthy ones, though the functional significance of this is not yet clear.

 

Part Two:
Ten asthmatic horses were divided into two groups: five received the polyphenol supplement, and five served as unsupplemented controls. All horses were maintained on a low-dust diet for four weeks, after which airway inflammation was deliberately exacerbated by feeding dusty hay for another four weeks. Throughout, the team assessed clinical signs, rebreathing examination findings, and pulmonary inflammation.

 

Findings: Supplemented horses demonstrated clear clinical benefits. They had significantly lower respiratory rates than controls during the dusty hay challenge, and fewer supplemented horses showed abnormal findings on rebreathing examinations. These improvements occurred despite evidence of ongoing airway inflammation, suggesting that supplementation may have helped to blunt the clinical impact of the environmental challenge.

 

The polyphenol supplement was well tolerated and readily eaten by horses when fed as a top-dressing, making it a feasible option in practice. Importantly, supplementation was not presented as a replacement for environmental management but rather as an adjunct. Controlling dust exposure, optimising ventilation, and feeding low-dust forages remain the cornerstone of asthma management in horses. However, dietary polyphenols may provide additional support by modulating inflammatory processes at both systemic and pulmonary levels.

 

This research provides preliminary evidence that dietary polyphenol supplementation can reduce airway inflammation markers and improve clinical signs in horses with mild-to-moderate equine asthma. While further work is needed to establish long-term effects, optimal dosing, and the mechanisms involved, polyphenols represent a promising area of nutritional support for respiratory health in horses. 

 

 

For more details, see:

 

K.M. Andrews, L.J. Berghaus, K.A. Hart,

Effects of mixed polyphenol supplementation on lower airway inflammation in horses with Equine Asthma Syndrome,

Journal of Equine Veterinary Science,(2025) Vol 154,105681,

https://doi.org/10.1016/j.jevs.2025.105681