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Topic:In Vivo
In vivo studies involving horses refer to research conducted within living organisms to understand various biological processes, disease mechanisms, and therapeutic interventions in equine species. These studies provide insights into the physiological and pathological responses of horses under natural conditions. In vivo research encompasses a range of investigations, including pharmacokinetics, disease modeling, and the evaluation of treatment efficacy. It often involves the use of controlled environments to simulate real-life scenarios while observing the effects of specific variables on equine health. This page gathers peer-reviewed research articles and scholarly studies that explore the methodologies, findings, and implications of in vivo research in horses, contributing to the advancement of equine science and veterinary medicine.
Comparison of Fogarty and Vollmar thrombectomy for chronic jugular thrombosis in horses. Chronic jugular vein thrombosis may result in persistent venous obstruction and impaired head drainage. Although surgical thrombectomy is performed in selected cases, experimental comparisons between mechanical techniques for chronic thrombus removal in horses are lacking. Objective: To compare Fogarty catheter thrombectomy alone with a combined Vollmar ring-Fogarty technique for restoration and maintenance of luminal patency in experimentally induced chronic jugular thrombosis. Methods: Randomised in vivo study. Methods: Chronic right jugular thrombosis was induced in 10 healthy adult horses....
Short-term effects of pulsed electromagnetic field therapy on subjective flexion-associated lameness responses and circulating cytokines in horses with distal tarsal osteoarthritis. Pulsed electromagnetic field (PEMF) therapy is commonly used in equine sports medicine for its proposed anti-inflammatory effects; however, limited controlled studies have evaluated its physiologic effects in horses. Objective: The objective of this study was to investigate the effects of PEMF therapy on flexion-induced lameness and circulating cytokines in horses with radiographic evidence of distal tarsal osteoarthritis. Methods: Six mares were enrolled in a repeated-measures crossover design in which each horse served as its own control. Horses were evaluated at baseline (sham PEMF) and at ...
Antimicrobial effects of equine regenerative medicine products: A systematic review and meta-analysis of in vitro and in vivo studies. Equine regenerative medicine products involving platelet-rich plasma (PRP), mesenchymal stromal cells (MSCs), and their derivatives are increasingly explored for antimicrobial and therapeutic roles, but their efficacy and between-study variability remain unclear. Objective: To systematically review and meta-analyse in vitro and in vivo evidence on antimicrobial effects of equine regenerative medicine products and to evaluate their efficacy against key pathogens. Methods: Systematic review and meta-analysis: METHODS: We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses...
Species-Specific Mechanisms of Sperm Transport: Predominant Roles of Motility in Ewes and Uterine Contractility in Mares. The factors controlling sperm transport within the female genital tract vary among species. The aim of this study was to quantify the respective roles of sperm motility and uterine contractions in passage of sperm within the reproductive tract of the mare and ewe. Sperm imaging was performed in vivo within the female genital tract of mares and ewes using probe-based confocal laser endomicroscopy (pCLE) after intrauterine insemination during two stages of the cycle characterized by high (oestrus) or low (luteal phase) uterine contractility. Fluorescent microbeads (2 µm in diameter) were insemi...
Intratumoral para-toluenesulfonamide as a tumor-ablative therapy for equine cutaneous tumors: a case series of three horses. Equine neoplasia, including sarcoids, melanomas, and squamous cell carcinomas, presents therapeutic challenges due to recurrence and limitations of conventional treatments. Para-toluenesulfonamide (p-TLS) is a tumor-ablating agent that is associated with localized tumor necrosis and subsequent lesion resolution. It has been evaluated in human clinical settings as an intratumoral treatment of malignant airway obstruction caused by non-small cell lung cancer. This study aimed to describe the clinical outcomes and tolerability of intratumoral p-TLS in equine neoplasia. Three equine cases, includi...
Sperm Energy-restriction and Recovery (SER) enhances equine sperm function and embryo development after ICSI. Assisted reproductive technologies (ART) are extensively used in domestic animal reproduction; however, improving their efficiency and consistency remains a major challenge for achieving reliable reproductive outcomes. The equine industry faces unique challenges related to sperm capacitation, which limited the success of conventional in vitro fertilization (IVF) for many years. Consequently, intracytoplasmic sperm injection (ICSI) became the most widely used technique for commercial in vitro embryo production. Even though a successful IVF protocol was recently developed, substantial opportunit...
Agreement of a veterinary-specific oscillometric noninvasive arterial blood pressure monitor (SunTech Vet30) with invasive arterial blood pressure in anaesthetised horses. To evaluate agreement between a veterinary-specific oscillometric noninvasive arterial blood pressure monitor and invasive arterial blood pressure (IBP) measurements in anaesthetised horses. Methods: Prospective clinical method-comparison study. Methods: A group of 46 horses undergoing general anaesthesia in dorsal recumbency. Methods: Paired invasive and oscillometric blood pressure measurements were recorded at 15-minute intervals. IBP was measured via a facial artery catheter, and systolic (SAP), diastolic (DAP), and mean arterial pressures (MAP) were recorded. Oscillometric measurements we...
Humoral immune response to equine mesenchymal stem/stromal cells (MSCs): MHC compatibility has more influence than inflammatory priming or chondrogenic differentiation. Mesenchymal stem/stromal cells (MSCs) hold great potential for treating various conditions, but their effectiveness and safety in allogeneic therapies can be affected by the recipient's immune response, among other factors. Allogeneic MSC administration has been associated with immune recognition in different species, including horses. These animals are both veterinary patients and translational models, offering valuable insights into how allogeneic MSCs interact with the immune system in vivo. Factors such as inflammation, chondrogenic differentiation, and major histocompatibility complex (MH...
Oscillometric assessment of bronchodilator response in horses with severe asthma during remission. During clinical remission of severe equine asthma (SEA), affected animals can be challenging to distinguish from healthy horses. In humans, the degree of bronchodilation achieved with a β-adrenergic bronchodilator is helpful in differentiating asthmatics from healthy subjects. Objective: To determine whether the response to an inhaled bronchodilator improves the sensitivity of oscillometry in detecting subclinical airway obstruction in horses with asthma. Methods: In vivo experiments. Methods: Nine control university-owned horses and 10 SEA horses in remission from a research herd were studie...
Cracks in the ice: biological challenges and incremental progress in equine oocyte vitrification. Equine oocyte vitrification could enhance the flexibility of in vitro embryo production, yet developmental competence remains reduced. Only vitrification of oocytes matured in vivo yields foaling rates comparable to fresh oocytes. Recent advances in vitrification at the germinal vesicle (GV) stage, supported by systematic comparisons of cryoprotective agents and exposure times, has enabled consistent blastocyst production and birth of several foals. Comparative studies of GV and metaphase II (MII) stages suggest biological advantages of vitrification after in vitro maturation (IVM), warranting...
Novel technique for correcting urovagina via urethral transposition in the horse. Vesicovaginal reflux is a common cause of infertility in mares. Surgical correction is commonly recommended and involves caudal relocation of the urethral orifice which forces the urine to be expelled caudally. There have been several previously described techniques. Complications associated with caudal urethral extension occur in 11-33.3% of cases. Objective: To identify a novel technique for performing caudal urethral translocation that effectively corrects vesicovaginal reflux with minimal associated complications. Methods: In vivo experiment and clinical case series. Methods: The experimen...
Vitrification of in vivo produced equine embryos: Size really does matter! Vitrification rather than slow-freezing has become the method of choice for the cryopreservation of in-vivo produced embryos. It is a simple technique that does not require a programmable freezing machine and relies chiefly on placing the embryo on a surface, rather than within a straw, in a small volume of vitrification solution to achieve extremely rapid cooling rates. However, in the field of equine embryo vitrification size truly does matter. Methodologies for both vitrification and warming prior to transfer are largely dictated by the size of the embryo. Since embryo size is directly rela...
Topical betulinic acid for treatment of equine melanoma and sarcoid. Betulinic acid, a natural pentacyclic triterpenoid, has demonstrated anti-inflammatory and anti-tumor properties in vitro, including activity against equine melanoma and sarcoid. However, there is limited in vivo evidence evaluating its clinical efficacy. The objective of this study was to assess the safety and efficacy of a compounded 1% betulinic acid cream for the treatment of equine cutaneous melanoma and sarcoid. Unassigned: This prospective, randomized, double-blinded, placebo-controlled clinical trial enrolled client-owned horses with melanoma or sarcoid tumors. Horses received either a...
Dexmedetomidine infusions improve cardiovascular and renal function in anaesthetised, experimentally endotoxaemic horses. Dexmedetomidine infusions are beneficial in anaesthetised endotoxaemic horses when administered concurrent to endotoxin, but post-conditioning effects are unknown. Objective: To evaluate whether a dexmedetomidine infusion is beneficial in horses administered Escherichia coli O55:B5 lipopolysaccharides (LPS) endotoxin prior to anaesthesia. Methods: Randomised controlled in vivo experiment. Methods: Ten systemically healthy horses were instrumented for acquisition of cardiac index (CI) using thermodilution. Horses received IV LPS (0.1 μg/kg bwt) immediately prior to anesthesia. Horses receive...
Effects of shoeing on forelimb biomechanics in walking horses. Hoof trimming and shoeing techniques are used to manage and prevent equine limb injuries. However, quantitative studies comparing the effects of different shoeing techniques on equine joint biomechanics over the full gait cycle are lacking. Objective: To measure and compare joint motion and net torques at the distal forelimb joints when horses walk overground unshod, with a standard flat shoe, and with a rocker shoe. Methods: In vivo study. Methods: Gait data were recorded from 12 sound horses during walking. Three shoeing conditions were tested: unshod, flat shoe, and rocker shoe. Data were r...
Equine Oocyte and Embryo Metabolism in the ART Setting: Current Knowledge and Clinical Significance. Equine in vitro embryo production has become very efficient and is used extensively worldwide for the clinical production of foals. What we know so far about offspring health and performance is promising; however, elements of the in vitro process remain unphysiological when compared to in vivo conditions. Studying the metabolism of oocytes and embryos can help inform the optimisation of culture systems and identify aberrations if they occur. Given the growing body of knowledge on the downstream effects of an inadequate peri-conception environment, both in vivo and in vitro, it is imperative th...
Erythrocyte sequestration of metformin in horses: impact on matrix-specific pharmacokinetics and detection windows. BACKGROUND: Metformin is used for the treatment of type 2 diabetes and is one of the most prescribed medications in human medicine. It is less commonly prescribed in equine medicine, and its use is tightly regulated in several performance horse disciplines. In horseracing, it is considered a banned substance. A previous pharmacokinetic study of metformin in horses demonstrated a prolonged, unpredictable elimination phase. In the current study it was hypothesized that this was due to sequestration of metformin in a “deep” compartment, specifically red blood cells. This could result in pharm...
Terpenic compounds possess anthelmintic and immunomodulatory properties with potential for controlling equine cyathostomin infections. The emergence of anthelmintic-resistant parasite isolates necessitates alternative control strategies. The use of dietary additives with anti-parasitic or immunomodulatory activities has been proposed as a solution, but whether such additives can simultaneously exert dual bioactivities within this context has rarely been explored. Here, we evaluated whether selected terpenes could exert dual bioactivities (anti-parasitic and immunomodulatory) with a view to their use as food additives that can limit strongyle infections in horses. In vitro tests with cyathostomin larval development, larval mig...
Radiation in Veterinary Practice: Paradigm Shift Toward Precision and Curative Approaches. Ionizing radiation therapy has undergone a clear paradigm shift in veterinary oncology and inflammatory disease management, moving from mainly palliative use toward structured, curative treatment programs. This review synthesizes current evidence on key modalities used in veterinary practice, including external beam radiotherapy, brachytherapy, systemic targeted radionuclide therapy, stereotactic radiosurgery, stereotactic body radiotherapy, radiosynoviorthesis, and low-dose radiotherapy. Each modality is discussed in relation to its physical and biological basis, major isotopes or beam types,...
Photodynamic therapy with infracyanine green induces keratocyte depopulation in the normal equine cornea. Use of photodynamic therapy (PDT) for the treatment of immune-mediated keratitis (IMMK) in horses is becoming common. The safety and morphologic impact on the normal equine cornea have not been investigated, and the mechanism of its efficacy is unknown. Objective: To investigate the morphologic effects and safety of in vivo PDT on healthy equine corneas. Methods: In vivo experiment. Methods: Six university-owned horses underwent unilateral corneal PDT with intrastromal infracyanine green (EmunDo®) and photoactivation with an 810 nm diode laser (500 mW for 2.5 min = 75 Joules). Compl...
Equine autologous platelet concentrate is a leukocyte-rich platelet-rich plasma with a high interleukin-1Ra-to-interleukin-1β ratio and high transforming growth factor-β1 concentration. To quantify platelets, leukocytes, cytokines, and growth factors in ProVet autologous platelet concentrate (APC). We hypothesized that APC would contain significantly increased leukocytes and platelets compared to whole blood and significantly increased concentrations of anti-inflammatory cytokines and growth factors compared to serum. Unassigned: Blood was obtained from 6 horses and processed to produce APC. Leukocyte and platelet concentrations were quantified in whole blood and APC. Cytokines, including interleukin (IL)-1β, IL-4, IL-6, IL-10, tumor necrosis factor-α, and IL-1Ra, and growt...
The high fundamental frequency in horse whinnies is generated by an aerodynamic whistle. Understanding why the frequencies of some species' vocalizations are far above or below those predicted by body size is key for explaining the remarkable diversity of mammalian vocal behavior. Horses, among the largest terrestrial mammals, provide a clear example of such deviation: their whinnies contain a very high fundamental frequency (>1,000 Hz) in addition to a second, lower one (∼200 Hz). While the lower fundamental frequency of whinnies is readily attributed to vocal fold (laryngeal) vibrations, the biomechanical processes underlying the production of the higher one remain unknown....
Equine Corneal Stromal Invasive Squamous Cell Carcinoma: Clinical and in Vivo Confocal Microscopic Features of 7 Cases. To describe the clinical and in vivo confocal microscopy (IVCM) characteristics of horses with corneal stromal invasive squamous cell carcinoma (CSI-SCC). Methods: Retrospective study of 7 horses with histopathologically confirmed unilateral CSI-SCC. Methods: Horses with corneal CSI-SCC were examined by laser scanning IVCM. Signalment, clinical findings, and histopathology results were compared with IVCM findings. Results: Clinical ocular lesions in all horses included a heavily vascularized, opaque, gray or tan, anterior or midstromal opacity invading the cornea from the limbus. The corneal ...
Confocal laser endomicroscopy: exploring endometrial image quality in relation to the oestrous cycle of mares. Assessment of the endometrium is an essential component of a breeding soundness examination in mares. The current reference standard for evaluating equine endometrial health is histopathological assessment of an endometrial biopsy, however, inconsistencies may arise when a single blinded biopsy is used. Confocal laser endomicroscopy (CLE) is non-invasive and enables real-time in-vivo imaging of the endometrium across multiple locations within the uterine lumen. An initial study revealed variation in CLE image quality between mares. Objective: This study aimed to compare the quality of endometr...
The majority of proximal sesamoid and condylar fractures occurred in horses identified as high risk by inertial measurement unit sensors. To determine whether targeted lesion-specific algorithms developed from data collected with accelerometer-based inertial measurement units worn by racing Thoroughbreds could retrospectively identify horses at high risk of incurring forelimb condylar or proximal sesamoid fractures. Unassigned: Fracture-specific algorithms were generated from July 2021 to December 2024 with accelerometer data from 42,623 races by 15,755 horses, including 54 races by 23 horses that subsequently suffered condylar fractures and 90 races by 31 horses that later sustained proximal sesamoid fractures. Fracture-specifi...
Standing superficial keratectomy provides long-term control of epithelial and stromal equine immune-mediated keratitis. To describe the demographics and treatment outcomes of horses definitively diagnosed with epithelial or stromal immune-mediated keratitis (IMMK) by use of in vivo confocal microscopy (IVCM) and/or histopathology. Unassigned: Medical records of horses presented to the Cornell University Equine Hospital definitively diagnosed with epithelial or stromal IMMK with IVCM and/or histopathology between 2020 and 2024 were reviewed. Patient signalment, affected eye(s), diagnostics, treatments, and outcomes were assessed. Unassigned: 22 horses met the inclusion criteria. The mean age was 16.9 years (SD, ...
Antiparasitic potential of Caesalpinia coriaria: Current evidence and prospects for equine health. Parasitic infections remain a major constraint to equine health and performance, and the worldwide rise of anthelmintic resistance is forcing a shift toward integrated parasite management and new complementary tools. Caesalpinia coriaria (Divi-divi) pods are exceptionally rich in tannins and have been proposed as a potential source of antiparasitic phytochemicals. This review summarizes the current evidence on C. coriaria, focusing on its relevance to equine gastrointestinal helminths. Most available data come from in vitro screening against ruminant nematode models (mainly Haemonchus contortu...
Comparative Evaluation of Follicular Flushing Frequency and Scraping Time During Ovum Pick-Up in Mares: Effects on Oocyte Recovery Rate and Technical Considerations. Transvaginal ultrasound-guided follicular aspiration or ovum pick-up (OPU) has become the standard technique for oocyte collection in mares for intracytoplasmic sperm injection (ICSI). Although repeated follicular flushes and wall scraping are commonly used to improve oocyte recovery rate (ORR), the relative contribution of each remains unclear. This study aimed to compare the effects of multiple flushes versus controlled scraping time on ORR in mares. A controlled trial was conducted in two phases: (1) an ex vivo phase using slaughterhouse ovaries (n = 32), and (2) an in vivo phase in c...
Cell and Gene Therapy in Equine Ocular Disease. Equine ocular disease is common and often challenging to treat using traditional methods. This has led to the development of new therapies. Like human medicine, veterinary medicine is adopting cellular and gene therapy as innovative approaches. Equine ocular disease is a particularly promising area for these techniques. Notably, immune-mediated diseases (such as immune-mediated keratitis and equine recurrent uveitis), ulcerative keratitis, and infectious ocular diseases are of interest. Several ocular gene therapy products are approved for use in humans, and more are currently being researched...
Endothelial glycocalyx of equine intestinal vessels: electron microscopic and immunohistochemical imaging. To visualize the endothelial glycocalyx in equine intestinal vessels using electron microscopy and immunohistochemistry and to evaluate the impact of induced endotoxemia on its integrity. Unassigned: 6 healthy horses free of gastrointestinal disease were anesthetized with dexmedetomidine, ketamine, and diazepam and mechanically ventilated under isoflurane anesthesia. Jejunal venous tissue samples were collected after perfusion fixation with lanthanum nitrate before and 120 minutes after endotoxemia induced by IV administration of 30 ng·kg-1 Escherichia coli lipopolysaccharide. For transmissio...
