Cardiac Arrhythmias and the Role of cTnI in Horses

While some arrhythmias in horses are benign and pose no significant health risks, others can
severely impact performance and, in some cases, become life-threatening. Accurate diagnosis and management are especially critical in performance horses, where cardiac efficiency directly affects athletic ability.

Unlike humans, where vascular disease can lead to heart attacks, such conditions are rare in horses. Instead, horses are more commonly affected by cardiac rhythm abnormalities (arrhythmias). The most frequent arrhythmia observed is atrial fibrillation, which can impair heart function but is often manageable.

More serious are ventricular arrhythmias—abnormal heart rhythms originating from the ventricles—which can lead to severe cardiac complications. Horses with myocardial toxicities often experience these arrhythmias, but because they tend to be intermittent, detection can be challenging.

In human medicine, cardiac damage is assessed using cardiac troponin-I (cTnI), a regulatory protein released into the bloodstream when myocardial (heart muscle) cells are damaged. cTnI is highly specific to cardiac muscle and plays a crucial role in heart contraction. Elevated plasma cTnI levels are widely used to diagnose and assess the severity of myocardial damage, particularly in coronary artery disease (commonly associated with heart attacks).

Since equine cTnI is structurally similar to human cTnI, diagnostic methods developed for humans have been adapted for use in horses. 

Researchers, led by Jonathan Foreman, at the University of Illinois Veterinary Teaching Hospital, conducted a study to establish reference values for cTnI in healthy horses, using a human chemiluminescence assay. They then compared these values to cTnI levels in horses with diagnosed cardiac disease, confirmed through electrocardiography (ECG) and ultrasonography. All full report of the work is published in Animals.

The researchers found that horses with atrial fibrillation sometimes showed mildly elevated cTnI levels, occasionally falling outside the normal reference range.

On the other hand, horses with ventricular arrhythmias had a 10-fold higher median cTnI concentration compared to those with atrial fibrillation.

These results suggest that measuring plasma cTnI levels could be a valuable diagnostic tool in horses with suspected ventricular premature contractions or ventricular tachycardia. The findings support the use of cTnI assays in equine medicine to detect and monitor cardiac disease, improving early diagnosis and management of potentially serious conditions.

For more details, see:

Jonathan H Foreman, Brett S Tennent-Brown,  Mark A Oyama,  D David Sisson. 

Plasma Cardiac Troponin-I Concentration in Normal Horses and in Horses with Cardiac Abnormalities

Animals (Basel) (2025);15(1):92. 

doi: 10.3390/ani15010092

Prospect of easier remote monitoring

 Remote monitoring of heart, muscle and breathing conditions may become easier following the development of an e-textile slicker (or rug) at Purdue University. 

Biomedical engineers and veterinarians have collaborated to produce the system that can monitor a horse’s cardiac, respiratory and muscular systems using Bluetooth technology. The e-textile garment can be used for long-term management of chronic health conditions in large animals, with the goal to have a version for human use.

 

Another advantage of the e-textile is that veterinarians and their support staff won’t have to shave the horse’s hair or use adhesives to place electrodes on the horse’s skin, which should make it more comfortable for the horse.

 

Findings of how the e-textile works is featured in a study published in the journal Advanced Materials.

Chi Hwan Lee, the Leslie A. Geddes associate professor of biomedical engineering in Purdue’s Weldon School of Biomedical Engineering, said the Purdue team developed a dual regime spray and technique to directly embed a pre-programmed pattern of functional nanomaterials into the fabric to add the e-textile capabilities.

 

“These specially designed e-textiles can comfortably fit to the body of humans or large animals under ambulatory conditions to collect bio-signals from the skin such as heart activity from the chest, muscle activity from the limbs, respiration rate from the abdomen or other vital signs in an extremely slight manner,” Lee said. “Our technology will significantly extend the utility of e-textiles into many applications in clinical settings.”

 

The team’s next steps involve developing continuous 24-hour monitoring of horses with chronic disease or those receiving care in a veterinary ICU.

 

“We believe that our technology will be helpful in diagnosis or management of chronic diseases,” Lee said, especially as demand increases for remote health monitoring.

 

“Remote health monitoring under ambulatory conditions would be useful for farm and household animals, as it could potentially minimize clinic visits, especially in rural areas. It would also increase the efficiency in managing a large number of farm/household animals at once from a distance, even overnight,” he added.

 

A real-life example would be the ability to monitor severe equine asthma, which affects 14% of adult horses.

 

“Continuous monitoring would allow early detection of disease flair-up before it gets serious, offering an opportunity to nip it in the bud,” said Laurent Couëtil, a professor of large animal internal medicine in Purdue’s College of Veterinary Medicine and collaborator in the study. “Remote monitoring opens the possibility of sending vital information to the veterinarian to help make timely and informed treatment decisions.”

 

For more details, see:

 

A Programmable Dual-Regime Spray for Large-Scale and Custom-Designed Electronic Textiles

Taehoo Chang, Semih Akin, Min Ku Kim, Laura Murray, Bongjoong Kim, Seungse Cho, Sena Huh, Sengul Teke, Laurent Couetil, Martin Byung-Guk Jun, Chi Hwan Lee

Advanced materials (2022) Vol 34, 2108021

https://doi.org/10.1002/adma.202108021

Heart irregularities in Thoroughbred racehorses.

 

Atrial fibrillation is the most commonly recognized disturbance of heart rhythm in athletic horses. It is an important cause of poor performance, and has implications for safety of horse and rider.

In atrial fibrillation (AF) the heart beats with a haphazard, “irregularly irregular” rhythm. The condition may be termed “paroxysmal” (when it recovers spontaneously within 72hrs) or “persistent” (which continues if not treated). 

 

Laura Nash and colleagues studied records of horses racing in Hong Kong over a ten-year period up to July 2017. They looked at the incidence of AF in poorly performing horses, and whether having had a previous episode of AF increased the likelihood of a horse being affected.

 

The full, open access, report of their study is published in the Journal of Veterinary Internal Medicine.

 

They report that, from a total of 96,135 race starts, atrial fibrillation was identified in 4.9% of horses, with an overall incidence of 2.7 episodes per 1000 starts. Many horses were retired after the first episode of AF.

 

Having had a previous episode of AF increased the risk of AF, and recurrence was more likely in horses that had been treated previously for persistent AF, than in horses that had previously had paroxysmal AF.

 

The researchers comment: “We identified a high rate of recurrence in Thoroughbred racehorses after both paroxysmal and persistent episodes of AF. This substantial AF burden could arise from underlying microstructural myocardial lesions and electrical remodelling.”

 

They concluded that, “although horses can have long and successful careers after AF, the arrhythmia should not be considered benign, and the suitability of horses to continue their racing careers should be assessed on an individual basis.”

 

For more details, see:

 

Incidence, recurrence, and outcome of postrace atrial fibrillation in Thoroughbred horses

Laura C Nath, Adrian D Elliott, Joe Weir, Peter Curl, Sarah M Rosanowski, Samantha Franklin.

J Vet Intern Med (2021) 35(2): 1111–1120. 

https://doi.org/10.1111/jvim.16063

EVJ video abstracts available

For the past couple of years, the Equine Vet Journal has been publishing video abstracts of some of its articles. They provide a quick glimpse of the subject to see if you want to delve further.

The diverse range of subjects has included:

• ·         The effect of mare obesity and endocrine function on foal birthweight in Thoroughbreds
• ·         Clinical insights: Treatment of laminitis
• ·         Water depth modifies back kinematics of horses during water treadmill exercise
• ·         Overground endoscopic findings and respiratory sound analysis in horses
• ·         Risk factors in equine transport‐related health problems

Each includes a link to the written abstract, often with free access to the full text paper.

Go to :

https://vimeo.com/user60560055

Detecting arrhythmias with a smartphone app.

A smartphone app can be a useful tool for identifying heart rhythm irregularities in horses, according to work presented at the annual congress of the European College of Equine Internal Medicine, which was held recently in Ghent, Belgium.

Clinicians from the Faculty of Veterinary Medicine at the Cardenal Herrera University (CEU UCH) in Valencia, Spain, validated an app that allows electrocardiograms to be carried out on horses using a mobile phone.

The study, conducted by CEU UCH professors Ignacio Corradini, Javier Enguel, Alicia Fernández and Marta Barba, is due to be published shortly.

Ignacio Corradini observes that  not only are apps to monitor health are commonplace in the daily lives of people, their use is also growing in the field of veterinary medicine.

 “With this research, we have shown that telemedicine and mobile phone apps can now also be used as tools for monitoring the health of horses and conduct a key diagnostic test such as an electrocardiogram. Conducting this test normally requires taking the horse to a veterinary hospital. But now, the field veterinarian, with their own phone, can conduct the electrocardiogram and send it digitally to the veterinarians who specialise in equine cardiology for their assessment.”

Ignacio Corradini (2nd left) and colleagues during the study to validate the app for electrocardiograms. (Photo CEU UCH)  

In the study, conducted in the University’s Veterinary Hospital, they evaluated the accuracy of the application on both sides of the chest to detect arrhythmias on a total of 50 horses, with and without prior arrhythmias. 

“The results have been excellent: the mobile phone has shown high sensitivity for detecting and characterising the cardiac arrhythmias of horses. There is great potential with this type of application” explains professor Corradini.  

He adds that the main benefit of the app is that it favours the earlier detection of arrhythmias, while they are more amenable to treatment.

Furthermore, the app will enable veterinarians to add the electrocardiogram as a common test during a routine check-up or during pre-purchase examinations.

However, the mobile phone-based electrocardiogram will not eliminate the need for more sophisticated equipment and specialist interpretation.

Corradini stresses, “an electrocardiogram is an electrophysiological test that requires great experience to be appropriately interpreted, and therefore, although the field veterinarian can obtain an electrocardiogram with this app, it is of vital importance for the test to be sent to a specialised equine cardiologist to be assessed.”

He adds: “The equipment used in hospitals is more sensitive and would noticeably enhance the initial information provided by the mobile phone electrocardiogram. This is why, if an arrhythmia is detected on a horse, the test should be repeated with a more sophisticated device in a hospital with specialists in equine internal medicine to confirm the result.” 

For more details, see:
https://medios.uchceu.es/actualidad-ceu/la-app-que-hace-electrocardiogramas-a-los-caballos