The latest
Current Research Projects
2025-2026 Projects
1. Investigation of Escherichia coli Virulence Factors in Diarrheic Horses
Dr. Luis G. Arroyo
Associate Professor, Lic. Med. Vet., DVSc, PhD, DACVIM
Acute colitis (or enterocolitis) is a frequently encountered gastrointestinal disorder in horses that can lead to a rapid generalized deterioration. It accounts for about 5% of admissions to equine hospitals and is associated with a mortality rate that can reach 30–
40%. Diagnosis could be improved, since at least 50% of cases remain idiopathic. To date, Escherichia coli is not recognized as a cause of colitis in horses, despite its ability to cause diarrhea in many mammals, particularly in young animal and some sporadic publications in horses. E. coli is a Gram-negative bacillus, regarded as the principal facultative anaerobe of the gastrointestinal tract in most species. It is generally commensal, but certain strains are pathogenic and classified into different pathotypes based on the presence of virulence factors. Preliminary data from a study seeking to identify bacterial markers of intestinal dysbiosis show a significant increase of E. coli in the feces of horses with undifferentiated colitis when compared to healthy horses. This leads to the hypothesis that specific E. coli strains with particular virulence factors may be involved in the development of colitis in horses that are currently classified as undifferentiated.
This study aims to compare the presence of several E. coli virulence factors in fecal samples from horses with undifferentiated colitis and from healthy horses. The second objective is then to isolate E. coli strains by culture from the positive samples to determine the presence of virulence genes in these strains by PCR, and the pathotype involved in horses with undifferentiated colitis.
2. Developing West Nile Virus Risk Forecasts to Support Equine Health Response and Planning
Dr. Korryn Bodner
Assistant Professor, DVM
West Nile virus is spread by mosquitoes and can cause serious brain and spinal cord illness in horses. In Ontario, case numbers can rise sharply in some years and regions, making it hard to know when and where horses will be at risk. This project will develop forecasting tools using data on horse infections, mosquito activity, dead bird reports, weather, and environmental conditions to identify higher risk locations and periods. These forecasts will help owners and veterinarians act early to protect horses across Ontario.
3. Advancing Electroarthrography for Clinical Use and Commercial Translation
Dr. Adele Changoor
Assistant Professor, BSc, MSc, PhD
Dr. Judith Koenig
Associate Professor, Mag Med vet, Dr Med Vet, DVSc, DACVS, DACVSMR
Osteoarthritis (OA) is the most common cause of lameness in horses and is characterized by progressive and irreversible cartilage degradation. Cartilage is the thin tissue that lines the ends of bones in joints and normally enables pain free movement. Early recognition of OA is important to be able to treat and potentially prevent disease progression, yet veterinarians have no easy way of identifying cartilage changes and objectively monitoring joint disease. Electroarthrography (EAG) is an innovative technology that evaluates cartilage through sensors placed on skin around a joint, such as the equine fetlock (metacarpophalangeal) joint. This is similar to the way heart health can be understood using electrocardiography. EAG, measured with a prototype measurement system, successfully followed OA progression and treatment in an equine fetlock model of early OA. Through this work, we found that the current adhesive electrodes, while very conductive, do not work well for horses because they can move during testing. This project aims to redesign the electrodes and validate the complete EAG system to ensure it accurately measures cartilage structure and joint biomechanics. We will work with an industry partner to develop the best electrode design and carry out validation studies with researchers at the University of Calgary. This research is expected to substantially advance EAG to produce a reliable and user-friendly measurement system that equine veterinarians can use to evaluate cartilage health in real time. Achieving the project aims would help move EAG from research into the clinic and dramatically improve how OA is managed in horses, while also laying the groundwork for developing EAG into a commercial product
4. Development and Evaluation of a Simulation-Based Training Model for Equine Laparoscopy: Enhancing Surgical Competency and Clinical Outcomes in Residency Training
Dr. Nicola Cribb
Assistant Professor, MA VetMB DVSc Diplomate ACVS
Dr. Alejandro Merchan Muñoz
Assistant Professor, LV, DVSc, DACVS-LA
Comparable technical challenges are encountered in arthroscopy, where precise spatial orientation, triangulation, and instrument control within a confined joint space are required. To address these challenges, the proposed simulator will incorporate anatomically accurate replicas of the equine fetlock, carpus, tarsus, and stifle joints. Each joint model will reproduce key arthroscopic landmarks, joint capsule dimensions. Furthermore, the simulator will include representative osteochondral fragments positioned in clinically relevant locations to allow trainees to practice fragment identification, grasping, and removal using standard arthroscopic instrumentation and portals. This design will enable realistic simulation of common clinical scenarios, promoting the acquisition and assessment of fundamental arthroscopic skills under controlled, repeatable conditions.
5. Optimization of Fluid Therapy in Anesthetized Horses: Establishing Dosing Recommendations Through Volume Kinetics
Dr. Carolyn Kerr
Professor, Clinical Studies, DVM
Balanced electrolyte crystalloid solutions (BES) are used perioperatively in anesthetized horses to replace fluid losses and maintain tissue perfusion; however, data on their distribution and elimination does not exist. Findings in other species suggest that current practices may result in horses receiving fluids at inappropriate administration rates and volumes. Volume kinetic analysis (VKA) is a technique used to evaluate the distribution and elimination (disposition) of fluids within body compartments, permitting the calculation of appropriate fluid doses and dosing intervals. Preliminary findings in conscious and sedated, euvolemic horses determined the feasibility of applying VKA in this species. This study aims to assess the pharmacokinetics of BES in healthy horses under general anesthesia, using two commonly used VKA protocols. We hypothesize that 1. BES elimination will differ from conscious horses and will depend on the anesthetic protocol; and 2. suboptimal fluid distribution will be present with both treatments compared to conscious horses. The study will employ a randomized, crossover design with eight adult mares receiving two different anesthetic maintenance protocols: Medetomidine-Isoflurane (Med-Iso) and Isoflurane (Iso). Anesthesia will be induced using a standard protocol. All horses will receive 20 mL/kg of Lactated Ringer’s solution (LRS) administered as a bolus over 30 minutes, followed by an infusion of 5 mL/kg/h. Blood and urine samples will be collected pre- and post-infusion to measure various markers. Heart rate, blood pressure, temperature, and urine output will be recorded at defined times throughout the study period. Ventilatory support will be provided to maintain constant arterial carbon dioxide levels. VKA analysis will be performed using a nonlinear mixed-effect model. Results from this study will facilitate the establishment of guidelines for intravenous crystalloid fluid doses and administration rates in euvolemic horses receiving isoflurane with or without an alpha-2 agonist infusion.
6. Understanding the cellular interactions of equine cord blood-derived mesenchymal stromal cells in equine tendon repair.
Dr. Thomas Koch
Professor, Department of Biomedical Sciences, DVM
Tendon injuries affect up to 15% of racing animals across their career. Unfortunately, due to tendon’s propensity to heal with nonfunctional scar tissue, the rate of re-injury and chronic pain after poor healing is high. Thus, our team has undertaken novel research using cord blood derived mesenchymal stromal cells (MSCs), a type of stem cell, to treat these injuries. We are already funded by Equine Guelph to understand if these cells may be able to persist in the injury site and improve outcomes after tendon injury. This work is ongoing and the live animal studies are expected to be completed in 2025. Through a new collaboration we have a unique opportunity to gain additional knowledge on how the stem cells affect tendon repair by employing cutting-edge laboratory techniques to characterize not only the types of cells present, but how these cells are interacting with one another in an injured tendon. Historically a difficult tissue to study due to its dense nature, our expanded team’s unique expertise and use of new innovative technologies provide an exciting opportunity to shed new light on how tendon cells heal tendon injuries, and how the addition of new therapeutics may affect this. This unparalleled understanding of tendon biology will lay the groundwork for ongoing development and refinement of treatment approaches aimed at improving outcomes for horses living with tendon injury.
7. Do equine cord blood-derived mesenchymal stromal cells affect mitochondrial function in stressed chondrocytes?
Dr. Thomas Koch
Professor, Department of Biomedical Sciences, DVM
Dr. Pavneesh Madan
Professor, Department of Biomedical Sciences, DVM
Osteoarthritis (OA) is a leading cause of lameness and reduced performance in horses, significantly impacting their health and athletic careers. Current treatments primarily manage signs but do not address the underlying causes of joint degeneration. Recent research in human medicine suggests that mesenchymal stromal cells (MSCs)—a type of stem cell—may offer longer-lasting relief than traditional treatments like corticosteroids. One promising mechanism is the ability of MSCs to transfer healthy mitochondria (the energy-producing parts of cells) to damaged cartilage cells, known as chondrocytes, potentially helping them recover from stress and function more effectively. This study aims to explore whether equine cord blood-derived (eCB) MSCs can improve mitochondrial function in stressed chondrocytes in a laboratory setting. Specifically, we will examine how chondrocyte mitochondria respond to stress and whether co-culturing them with eCB-MSCs can reduce this stress. Using advanced imaging and cell analysis techniques, we will assess cell health, proliferation, and DNA damage. Although we do not yet have preliminary data for this specific project, our team has extensive experience studying mitochondria in other cell types. If successful, this research could lay the groundwork for future studies on how eCB-MSCs might be used to treat joint diseases in horses more effectively. Ultimately, this work could lead to improved therapies that not only alleviate signs but also target the root causes of equine osteoarthritis.
8. Enhancing Septic Arthritis/Osteomyelitis Treatment in Foals: Exploring the Synergy of Activated MSCs and Antibiotics.
Dr. Judith Koenig
Associate Professor, Mag Med vet, Dr Med Vet, DVSc, DACVS, DACVSMR
Mesenchymal stromal cells (MSCs) are recognized for their potent anti-inflammatory, antibacterial, and immunomodulatory properties, making them a promising therapeutic option for combating antibiotic resistance and biofilm-associated infections. This report describes the successful treatment of septic arthritis and osteomyelitis in a foal using equine allogeneic cord blood-derived MSCs (CB-MSCs) in combination with antibiotic therapy. An 8-day-old Thoroughbred filly was initially presented with septic arthritis of the right tibiotarsal joint, pneumonia, and omphalophlebitis/arteritis. Subsequently, the filly developed septic arthritis of the left elbow joint, epiphysitis, and osteomyelitis of the ulna, which progressed to a pathological fracture.
Due to limited clinical and cytological improvement following needle lavage, arthroscopic lavage, and intra-articular antibiotic administration, the left elbow joint and fracture site were treated 3 times with 15 million TLR3-activated CB-MSCs in combination with 500 mg of meropenem. Additionally, the filly received twice systemic treatment with non-activated CB-MSCs (1 million cells/kg body weight IV, 2 doses). During the MSC therapy period, chloramphenicol was administered systemically. The treatment completely resolved both septic arthritis and osteomyelitis. At a 12-month follow-up, the filly remained sound, and radiographic re-evaluation showed significant remodelling of the ulna.
This case highlights the successful use of equine allogeneic CB-MSCs—both locally and systemically—in conjunction with antibiotics, to treat a refractory intra-synovial and osseous septic process in a foal. Including TLR3-activated CB-MSCs likely enhanced antimicrobial efficacy, underscoring the therapeutic potential of CB-MSCs’ antimicrobial, anti-inflammatory, and immunomodulatory effects
9. The effect of an automated horse hay feeder on horse behaviour
Dr. Katrina Merkies
Professor, Animal Biosciences, PhD
Feeding is one of the most important factors affecting horse health and welfare. In natural environments, horses spend most of their day grazing, moving and interacting with other horses. In contrast, many domestic horses may be fed in a way that conflicts with their evolutionary adaptions. Providing ad lib access to hay for domestic horses helps prevent long gaps between meals but can lead to overeating and obesity, increasing the risk of painful and potentially lifethreatening metabolic diseases. Restricting hay to manage weight can cause frustration and increase the risk of ulcers, colic and stereotypic behaviours. Automated feeders (AFs) are an emerging technology that can provide hay in smaller amounts multiple times per day, supporting natural foraging behaviour while helping manage calorie intake. This study will explore horse behaviour when using an AF compared with traditional ad lib hay feeding. Twenty horses will be monitored using Hoofstep™ halters, which track movement and behaviour continuously, along with live observations. We expect that horses will initially show more movement and social interactions when being fed from the AF but that these behaviours will change as they become accustomed to it. By understanding how horses adapt to automated feeding systems, this study aims to help owners, caretakers and industry partners develop feeding practices that better support both physical and emotional well-being of the horse. Ultimately, this research will provide evidence-based guidance to improve the design and use of automated feeders, balancing the benefits of natural feeding rhythms with management practices.
10. Intraoperative Assessment of Tissue Perfusion and Blood Flow Using Near-Infrared Fluorescence Imaging with Indocyanine Green in Clinical Cases Undergoing Exploratory Laparotomy Under General Anesthesia
Dr. Alejandro Merchan Muñoz
Assistant Professor, LV, DVSc, DACVS-LA
When a horse is undergoing emergency exploratory laparotomy for colic, a key component of this surgery is evaluating whether the affected intestine has an adequate blood supply. Currently, this assessment relies primarily on the surgeon’s visual impression. This study aims to determine whether Near-Infrared Fluorescence (NIRF) imaging with indocyanine green (ICG) can provide a real-time, objective measurement of intestinal blood flow and tissue viability. The goal is to improve intraoperative decision-making and support better surgical outcomes for equine colic patients in the future.
11. Capturing the expertise of equine veterinary professionals to define the role of health in the Five Domains Model
Dr. Christopher B. Riley
Department Chair, Professor of Clinical Studies, DVM
Equine veterinarians are experts in the management of equine physical health. However, contemporary animal welfare science recognizes that good welfare extends beyond physical states such as health and nutrition. The Five Domains Model provides a systematic framework for assessing how nutrition, physical environment, health, and behavioural interactions influence an animal’s mental state, recognizing that welfare is best understood as the overall balance of positive and negative mental experiences. While this model is widely adopted in animal welfare science, it has not yet been fully operationalized into practical tools for equine clinical practice, where welfare assessment often remains focused on health and body condition. Using a survey, we seek to understand equine professionals’ familiarity with the Five Domains Model in Canada and other English-speaking countries, and compare these findings with those in New Zealand, where the framework was first developed and has been more widely socialized. We will also capture equine veterinary professionals’ judgement as to horses’ likely mental experiences across common health scenarios, informing subsequent co-design of a practical clinical aid for equine welfare assessment. This is the first step in bridging this gap by exploring the health domain and ultimately how it and the Five Domains Model may be integrated into equine veterinary practice.
12. Driving Toward Optimal Welfare: Addressing the Needs of Working Cart Donkeys in Kenya
Dr. Christopher B. Riley
Department Chair, Professor of Clinical Studies, DVM
Working equids play a crucial role in supporting the livelihoods of vulnerable communities worldwide, including those in Kenya. In Meru County, working donkeys are essential for household income, performing demanding labour that would otherwise fall to family members. However, current harnessing methods used for donkey carts have been identified as a major welfare concern, often causing pain, wounds, and breathing difficulties. Despite the efforts of welfare organizations, improved harnesses and carts are rarely adopted on a lasting basis. Common barriers include limited community involvement and approaches that are not locally sustainable. This project adopts a participatory approach, engaging donkey owners and drivers directly in the design, construction, and modification of harnesses and carts to enhance donkey welfare. Their feedback will shape the development of welfare-friendly carts tailored to their needs and working conditions. The project will also assess donkey movement and behaviour while pulling these improved carts, comparing signs of pain, breathlessness, and lameness to those observed with current carts. In addition, focus group discussions and in-depth interviews will explore current attitudes toward donkey welfare and the role of welfare organizations. By improving the working conditions and health of donkeys in Meru County, this initiative aims to enhance the well-being of over 8,000 donkeys and the families that depend on them. The lessons learned will help identify barriers to long-term adoption of welfare-friendly harnesses and carts, paving the way for sustainable improvements across Kenya and beyond.
13. Effect of fluid boluses of 5% hypertonic saline or 0.9% isotonic saline on arterial blood acid-base and electrolytes when used to treat hypotension in anesthetized horses
Dr. Alexander Valverde
Professor, DVM, DVSc., Diplomate ACVAA
Hypotension (low arterial blood pressure) is a common occurrence in anesthetized horses and can be present in patients with a normal or decreased circulating blood volume. Reasons for hypotension include blood loss, dehydration, vasodilation, and decreased cardiac function. Hypotension is associated with higher morbidity/mortality in anesthetized horses because it affects organ perfusion during anesthesia and increases the risk of myopathy and fatalities in the recovery period. Treatment for hypotension in anesthetized horses includes adjustment of the anesthetic depth, administration of intravenous fluids, and use of sympathomimetic drugs; the latter can increase heart contractility and/or vascular tone, most commonly with dobutamine. Among intravenous fluids, hypertonic sodium chloride (5%) can be used at low doses because its increased concentration contains a higher amount (> 5 times) of sodium than blood and isotonic solutions, which attracts fluid from outside the blood vessels into the circulation and can help normalize transiently the circulating volume and arterial blood pressure. In addition, hypertonic saline increases heart contractility and regulates vessel tone, both which help mobilize this augmented circulating volume and results in a higher arterial blood pressure.
Despite these benefits, the increase in electrolytes (sodium and chloride concentrations) from the hypertonic solution can affect the pH of the blood and acid-base balance and dilute the amount of potassium and hemoglobin in blood, which can affect tissue function and oxygenation. This project will assess the effects of hypertonic (5%) and isotonic sodium chloride (0.9%) in horses that develop hypotension during general anesthesia in two fronts: 1) On the acid-base balance, electrolyte blood changes (sodium, chloride, potassium), and the changes from hemodilution on hemoglobin (Hb), packed cell volume (PCV) and total protein (TP), and 2) On the change in circulating volume and the effectiveness of both solutions on improving arterial blood pressure. We will compare the changes in electrolytes to established predictive formulas validated and in current use in human medicine, to seek their applicability in horses and be able to validate these formulas or modify them, to precisely predict changes in electrolytes, circulating volume and arterial blood pressure from their administration in horses.
14. Ultrasonographic evaluation of caudal vena cava diameter as a non-invasive tool to guide fluid therapy in sick neonatal foals.
Dr Luiza Zakia
Assistant Professor, DVM, DVSc, DACVIM (LA), PhD Candidate
Young foals are at high risk for life-threatening illnesses that can cause significant loss of fluid from the body. This severe loss of fluid can limit the body’s ability to perform vital functions like circulating oxygen to the organs. The ability to accurately access the severity of this fluid loss is key to appropriate treatment of the foal. Currently, there are no highly accurate ways of doing this in sick, young foals. However, in other species, measurements of a large vessel in the abdomen (caudal vena cava) with an ultrasound are strongly correlated with the amount of fluid loss that has occurred and how the patient is responding to the current treatment plan. A previously published study has shown that this vessel is visible with ultrasound in young foals and that measurements of the vessel are reliable. Determining if, like in other species, these ultrasound measurements correlate well with how much fluid a foal has lost and how the foal is responding to the treatment plan is vital information for improving our ability to care for very sick young foals.
All Active Research Projects (as of 2025)
New Research Projects in 2023-2024
New Research Projects in 2022-2023