Researchers from the Ontario Veterinary College (OVC) and University of Toronto are developing a novel method to measure the quality of cartilage in horses using electroarthrography (EAG). EAG is a non-invasive technique that uses electrodes attached to the skin around a joint to detect electrical signals produced by the cartilage when it is loaded.

Dr. Adele Changoor, from the University of Toronto and Lunenfeld Tanenbaum Research Institute, and Ontario Veterinary College researcher Dr. Judith Koenig from the department of Clinical Studies, explained how EAG works and why it may become very useful for predicting cartilage quality and diagnosing osteoarthritis and other degenerative joints diseases in horses.

EAG is analogous to electrocardiography (ECG), which measures the electrical activity of the heart. Cartilage produces electrical signals during loading and these signals reflect its biomechanical properties, such as stiffness and permeability.

“By measuring EAG signals, we can get an idea of how healthy the cartilage is,” said Changoor.

Healthy cartilage ensures joints can move without pain and has an important role preventing wear and tear on bone. 

Currently, there are no readily available tools to assess cartilage quality in horses with the exception of diagnostic arthroscopy – a minimal invasive surgery – under general anesthesia. X-rays and ultrasound are not sensitive enough to detect cartilage changes, and magnetic resonance imaging (MRI) is expensive, requires anesthesia and is often difficult to access. EAG offers a potential alternative that is fast, easy and affordable.

“EAG is a promising tool for detecting cartilage damage early allowing intervention with treatments that can slow down or prevent further deterioration of the joint,” said Koenig. “EAG could also help us monitor the effectiveness of treatments over time.”

EAG measurements were collected at the same time as centre of pressure (COP), which measures the distribution of force under the horse’s hoof when it stands or walks.

“EAG is really tied directly to cartilage biomechanical properties,” said Changoor.  “We also needed to know about the joint biomechanics in order to interpret EAG properly.”

A custom, portable, force mat was developed by Dr. Changoor’s graduate students that included an array of force sensors to place under the horse’s hoof when measuring EAG.  

“Then we can measure how much compressive force or ground reaction force is being exerted on that joint,” said Changoor. “COP, is where the ground reaction force is acting. The ground reaction force gives us the total load on the joint. COP lets us figure out where on the hoof or where on the joint surface force is being concentrated.”

COP provides information about the joint biomechanics and the horse’s balance and stability. EAG and COP testing were combined to get a comprehensive picture of the joint health and function in horses with osteoarthritis. Results were compared with MRI imaging and it was found that EAG and COP testing correlated well with MRI and could detect differences in cartilage quality between healthy and osteoarthritic joints.

In the 2023 study involving horses with osteoarthritis in the fetlock joint, the horses were treated with MSCs to decrease inflammation and stimulate tissue healing. The researchers measured EAG, COP and MRI before and after the treatment to evaluate its impact on cartilage quality.

“We observed that MSCs improved cartilage quality in some horses and EAG and COP testing were able to capture these changes and show the responses to treatment. This suggests that EAG and COP testing could be useful for selecting treatment options for the horse,” said Dr. Koenig. “One of the biggest advantages of EAG is that it seems to correspond with our arthroscopic findings. It can perhaps evaluate the quality of the cartilage or cartilage defects, which we are at the moment only able to evaluate with arthroscopy.”

The researchers plan to conduct further studies in order to validate and refine EAG and COP testing for predicting cartilage quality in equines. They hope that these techniques will become widely available and accessible for veterinarians and horse owners in the future.

“This is an exciting and innovative research project that has the potential to improve the diagnosis and early management of osteoarthritis in horses,” said Dr. Koenig  “Osteoarthritis is a major health and welfare issue for horses and their owners, and we need better tools to detect it early and treat it. EAG and COP testing could provide a simple, affordable and accurate way to assess cartilage quality and joint function in horses.”

The graduate students who worked tirelessly on the EAG study include Peter Suderman, PhD Candidate in the Department of Materials Science & Engineering at U of T; Jaylon Pascual, undergraduate co-op student finishing her fourth year in the Biomedical Engineering program at U of G; Dr. Rodrigo Munevar Luque, Equine Sports Medicine Resident at OVC and PhD Candidate Biomedical Sciences at U of G; and Undergraduate Research Assistants in Clinical Studies, Ashley Nixon, DVM 25 (OVC), Pjotr Roest DVM 26 (OVC), and in Biomedical Sciences, Axel Koenig Parris HBA 25 (Ivey School of Business, Western University) and Rebecca Mullin BSc OVC 25.

The study was funded by the Equine Guelph Research Fund and the Natural Sciences and Engineering Research Council of Canada (NSERC). 

(Equine Guelph)