Grayson-Jockey Club Research Foundation’s board of directors has announced a slate of 19 research projects which the Foundation will fund for a total of $1,003,580 in 2014. The list includes eleven new projects and five which are in their second year, as well as three Storm Cat Career Development Awards. The allotment brings the Foundation’s total impact since 1983 to $20.9 million to fund 310 projects at 41 universities.
From research performed in the past decade it has emerged that there are three distinct major forms of laminitis. One of them is supporting-limb laminitis. Although it has never been proven, supporting limb laminitis is suspected to occur as a result of reduced blood supply to the connection between hoof and bone (the lamellar tissue). It is proposed that horses rely upon regular loading and unloading of the foot in order to move blood (containing nutrients and oxygen) through it. Our research groups (Queensland, U of Penn, and Ohio State), supported by the Grayson-Jockey Club Research Foundation, now have strong preliminary data that supports this theory.
This next step will utilize a protocol that combines real–time monitoring of lamellar tissue blood flow and energy balance with a suitable and humane model of preferential weight bearing on one limb. We seek to confirm the cause of supporting limb laminitis and to test potential therapeutic interventions. It is anticipated that the results of this study will directly guide the design of devices and/or protocols that can be used in the clinical setting to prevent supporting limb laminitis.
An effective preventative strategy would be a significant step forward for the welfare of horses and for the horse industry.
After many decades of frustration with failures of multiple therapies, we now have one therapy, continuous digital hypothermia (CDH), which has proven effective in the laboratory and clinical setting in many horses. We will use advanced biochemistry techniques, combined with two cutting edge research tools including kinome arrays and metabolomics analysis. The results will provide targets for pharmaceutical therapies to either replace or augment CDH, and will also for the first time determine effects of CDH in the normal digit (important to know for any commonly used therapy).
Advancing laminitis therapy will allow more at- risk animals to avoid the crippling consequences of SRL and return to their previous level of function in the equine industry as was witnessed with Paynter.
We have developed a novel method for bacteria so they are absolutely unable to reproduce but remain immunologically intact by using electron–beam technology. Moreover, we have demonstrated that e–beam–irradiated isolates of R. equi administered orally can stimulate R. equi–specific immune responses in very young foals. Thus, the primary aim of this study is to determine whether administration of e–beam–irradiated R. equi administered orally to foals during early life can protect against experimental infection of the lungs with live R. equi. As a secondary aim, we will examine selected indicators of immune responses to the vaccine.
To summarize, we propose to evaluate the ability of this vaccine to protect foals against infection with R. equi as an essential next step in our efforts to develop a vaccine against R. equi. and subsequently other infections such as Strep equi, the causative agent of strangles.
We presume that these deaths are caused by heatstroke. Our theory is that the overheating problem is similar to anhidrosis (nonsweating), in that the ability to sweat is impaired. We have good evidence for this in the case of erythromycin, based upon studies done in preparation for this proposal. This makes the foal unable to efficiently lose body heat, and on hot days, puts it at risk for heatstroke. We have developed a way to measure precisely the ability of horses to sweat. We plan to use this simple test to show that impaired sweating is the cause of overheating not only in foals given erythromycin but also in some foals treated with azithromycin, clarithromycin, and even the exciting new antibiotic, gamithromycin. Some additional studies will be dedicated to trying to sort out how this class of drugs affects sweating.
If we are right, we hope that these results will serve as a wake-up call for all concerned that foals on erythromycin–like drugs including azithromycin, clarithromycin, and gamithromycin are at risk for heatstroke during and even after treatment and they therefore need to be protected by implementation of common–sense heat control measures.
Data gathered in this study will provide valuable information for the duration of effect of this drug in the horse by measuring up-regulated genes and inflammatory proteins, in both normal and inflamed joints. If, as we have theorized, this drug has a prolonged effect relative to detection times, results from this study may support less frequent administration of intra-articular corticosteroids, which may ultimately prove beneficial to the health of the joint.
Mild and severe injuries to the fetlock are very common. Catastrophic injuries to the fetlock are the greatest cause of death in racehorses, causing about 50% of injury related deaths. Fetlock injuries are due to circumstances that cause the fetlock to extend beyond its normal range of motion (hyperextension). We hypothesize that fetlock hyperextension, and thus related injuries, can be prevented by developing race surfaces that change the way the limb interacts with the surface. Our objective is to determine the characteristics that a race surface should have to prevent fetlock injuries.
It is not economically practical to build the number of race surfaces needed to determine the ideal surface for injury prevention. Thus, a computer modeling and simulation approach is being used because it is a powerful and economical tool for investigation of race surface characteristics on fetlock motion, and thus risk for injury. This approach can be used to assess the effect of surfaces presently installed, as well as those surfaces that do not presently exist. Racehorse fetlock motion will be predicted for a large number of surfaces with different characteristics. Because the predictions are only as good as the computer model, the model will be evaluated for accuracy (validated) by comparing predictions with actual race surface behavior and racehorse fetlock motion that we previously measured simultaneously at two racetracks, one with a dirt surface and one with a synthetic surface. After validation, the model will be used to determine race surface characteristics that prevent fetlock hyperextension. These race surface characteristics can be used as a standard guide.
Unfortunately, routine diagnostic methods (radiographs , ultrasound, MRI, CT) all have shortcomings in evaluating articular cartilage, although MRI is currently the preferred imaging method. However, when contrast agents are injected into the joint prior to CT imaging (CCECT), they have the potential to provide far more information about the health of cartilage. In preliminary experiments we have demonstrated that the amount of CCECT contrast in the cartilage is strongly related to the amount of GAG content within articular cartilage in normal joints. Our hypothesis is that CCECT is a safe and useful method to improve early diagnosis of joint disease. We will test this hypothesis by determining GAG concentrations in normal and diseased articular cartilage and comparing those amounts to CCECT attenuation. We will also test the safety of the contracts agent by evaluating articular cartilage samples for toxicity and lastly, compare the CCECT imaging modality to MRI. It is anticipated that in these experiments we will be able to demonstrate that decreasing GAG content is measurable using contrast CT studies allowing for the early detection of cartilage injury using readily available equipment.
The completion of this project will allow for the critical evaluation of CCECT as a method for the detection of early osteoarthritis in horses and will allow for applications of its use in clinical patients. If this method proves to be effective, it can be a useful tool for monitoring future treatment protocols in horses as well as future cartilage research as it offers a way of ante-mortem in depth evaluation of cartilage health.
Under experimental conditions, we have shown that equine platelets exposed to EHV1 undergo a procoagulant activation response and then bind to and transfer EHV1 infection to equine endothelial cells. Our proposal builds on these observations to test the hypothesis that experimental infection with EHV1 induces an in vivo procoagulant platelet phenotype, and that administration of phosphodiesterase inhibitors will decrease EHV1 induced platelet activation.. Results from EHV1 infected and sham infected horses will be compared and we will relate changes in platelet and coagulation parameters to recorded clinical signs (e.g. fever), platelet counts and level of viremia.
We expect to find evidence of platelet and coagulation activation during the acute phase of EHV1 infection and that horses demonstrating more profound activation response will also have more severe fever.
We will also compare the inhibitory effects of 4 antiplatelet drugs on EHV1 induced platelet activation. We expect that, the phosphodiesterase inhibitors will have the most inhibitory action on the ability of EHV1 to induce platelet procoagulant activity. EHV1 infection results in microvascular thrombosis that contributes to the clinical syndromes of abortion and EHM. For instance, horses that have severe neurological symptoms, such as paralysis or paresis, frequently have to be euthanized. Horses that do survive may not be able to race or may have decreased future racing performance due to the persistence of neurologic signs. By preventing or minimizing thrombosis, we can potentially decrease or eliminate these two severe clinical manifestations of EHV1 infection.
Successful completion of this study will show that, for the first time, platelets are activated in vivo in horses with EHV1 infection and that we can potentially inhibit platelets from participating in thrombosis, using available phosphodiesterase inhibitors. These affordable drugs, which are currently used in horses to treat airway disease, endotoxemia, laminitis and navicular disease, could readily be administered to exposed or known infected horses, including pregnant mares, to reduce or prevent the devastating sequelae of EHV1 infection. By inhibiting platelet function, we have our first real chance of preventing thrombosis and the clinical syndromes of abortion and EHM in horses.
Our work with the genome led us to find that R. equi produces specific appendages termed “pili” that mediate attachment to host cells. We also found that these pili are essential for lung colonization and confer full protection when used as a vaccine in mice. This project aims to test the protective efficacy of this novel R. equi pili vaccine candidate in foals. R. equi infection is contracted during the first days of life and the immune system of young foals is incapable of stopping the pathogen once it is established deep in the lung tissue, resulting in life–threatening purulent pneumonia. We believe that protection against this pathogen can be achieved by targeting the pili with a vaccine that will prevent infection when still at its initial “colonization” stages in the airways before the bacteria become established in the lung. If the trial that will be conducted in this project is successful, the R. equi pili will form the basis of a commercial vaccine to control rhodococcal infection in stud farms.
The triggering factors for IAD are not known but studies have implicated exposure to barn dust. On the other hand, studies have also supported a role for bacterial infection of the airways. The levels of airborne irritants horses are exposed to in the barn environment can be measured, and airway secretions can be sampled in order to classify the type of airway inflammation present in an individual horse. Combining these techniques will allow examination of the relationship between barn exposure and airway inflammation. In the past, investigations of the role of bacteria in IAD have relied upon time-consuming and relatively insensitive culture of mucus. Currently, DNA sequencing is a highly sensitive method that can be used to identify all the bacteria present in mucus, thereby characterizing the entire airway microbe population, or so-called “microbiome.” In addition to bacteria, viruses may cause airway inflammation. Again, DNA sequencing has improved the ability to detect viruses. This study is designed to explore the possibility that the various types of airway inflammation differ in their impact upon racing performance in horses and are due to different causes. Studying these differences is important to develop targeted prevention and treatment strategies.
More recently a clinical trial reported success rates of 89% and 94% for 1 and 2 mg/kg once daily, respectively, with a number of factors potentially contributing to the efficacy of the lower doses observed. Of these factors it is possible that the administration immediately prior to work favored the low doses as exercise is the period in which the most damage to the squamous mucosa occurs. Likewise, administration following fasting may have been beneficial since fasting will improve omeprazole absorption. However, in a study comparing pre– vs. post–exercise administration of an alkaline–buffered omeprazole formulation (similar to GastroGard®), no clear benefit of these two factors was observed, which suggested that the formulation of omeprazole was responsible for the improved efficacy at lower doses. However, while direct comparison of the formulations has not been reported, preliminary data from an ongoing study suggests, at least indirectly, that absorption of the two formulations is similar. If equivalence could be demonstrated then the cumulative effect of the above discussion is that lower doses of omeprazole could be used in the treatment of squamous ulceration. This, combined with the imminent expiration of the GastroGard® patent and entry of generic formulations onto the market, would greatly increase affordability of the drug for the treatment of horses worldwide.
With the above in mind the aims of the study are: (1) to compare absorption of a range of commercially available omeprazole formulations; (2) to investigate the magnitude and duration of acid suppression achieved following administration of two doses of omeprazole under two different feeding conditions; (3) to develop a pharmacokinetic/pharmacodynamic model, where the concentration of drug in a blood sample is used for the prediction of an individual’s therapeutic response, for omeprazole in the horse; and (4) combining the findings from 1 – 3, develop a revised set of treatment recommendations for the treatment of gastric ulcers in the horse.
Recently, commercial tests have been developed for use in food safety microbiology which may provide a practical and useful alternative to traditional culture and polymerase chain reaction (PCR) methods when screening for Salmonella. These lateral flow immunoassays could be economically employed in point–of–care testing providing a 24 hour test result for fecal samples and 48 hour test results for environmental samples with reasonable sensitivity. This will allow more extensive yet less expensive use of screening to control Salmonella in veterinary settings. The Central Hypothesis for this work is: Commercially available test strips used in the food production industries can be adapted for use as a rapid, point–of– care test to detect Salmonella in horse feces or environmental samples with sensitivity that is equivalent to optimized culture or PCR testing. To address this central hypothesis we will identify an optimal culture technique for fecal cultures and use an established culture protocol for environmental samples. We will also test these samples with a validated commercial PCR test kit, and with the Reveal® 2.0 rapid test strip. We will use these test results to estimate the sensitivity and specificity of these tests using state–of–the art, best–practice epidemiological methods.
The Storm Cat Career Development Award, inaugurated in 2006, is a $15,000 grant designed as an early boost to an individual considering a career in equine research. It has been underwritten annually by Mrs. Lucy Young Hamilton, a Grayson-Jockey Club Research Foundation board member whose family stood the retired champion stallion Storm Cat at Overbrook Farm. In each of the last two years, the Foundation board had authorized two Storm Cat Awards in addition to the award provided by Mrs. Hamilton. Three candidates have been selected to receive the Annual Storm Cat Career Development Award. They are:
A more sensitive method to evaluate cartilage with decreased anesthetic time is warranted in horses. With the advent of multi-slice computed tomography (CT), costs and scan length have decreased (minutes) while having improved spatial resolution compared to MRI.
Contrast agents can be injected into the joint to help outline articular structures for X-ray based imaging including contrast enhanced computed tomography (CECT). Preliminary experiments in our group have demonstrated a strong correlation between equine articular glycosaminoglycan (GAG) content and CT attenuation in normal cartilage explants. We hypothesize that decreased equine articular cartilage GAG content will be detectible and correlative with CT attenuation using a CA4+ contrast agent in an impact model of osteoarthritis. To test this hypothesis, we aim to determine correlations between articular cartilage GAG content and CT attenuation (CECT) with cationic contrast agent (CA4+) in horses where degenerative GAG concentrations in articular cartilage are created by an impact injury.
We hypothesize that lubricin may enhance functional repair throughout the joint, and in-so-doing, reduce pain and the progression of disease. We contend that current joint medications don’t mimic resident biology in a joint, and provide a short term resolution for a chronic problem. Lubricin has been identified as the primary boundary lubricant in synovial fluid, which prevents cartilage roughening and degradation under high-load, low-motion conditions by decreasing friction at the articular cartilage gliding surfaces. In addition, lubricin is proposed to protect against the development of OA by decreasing joint lining cell adhesion to the articular cartilage surfaces, inhibiting joint lining overgrowth and scar tissue formation, and stimulating synthetic action from the joint lining to increase other joint fluid constituents. These features make lubricin an ideal joint medication when administered by injection. Despite this obvious potential, little is really known about the changes in lubricin levels or molecular organization with joint disease (fracture or arthritis), the effect of lubricin on tissues that make up the joint, on ways to enhance its impact as a high-load lubricant, and on dosing or longevity of the molecule after injection.
The broad objectives of this proposal are to examine the lubricin levels in joints with various stages of joint damage (from normal through reactive to obvious arthritis), to assess the organization of lubricin on the cartilage surface, and to determine the impact of lubricin on cartilage and joint lining tissues. This information will provide key information in the development of a lubricin treatment protocol. Studies so far suggest that lubricin protects articular cartilage from fibrillation by functioning as a boundary lubricant and by preventing joint lining cell overgrowth and protein deposition. We seek to understand the underlying mechanisms by which lubricin confers these properties in the joint.
In foals, endocrine maturation occurs in late gestation and continues into the early post-natal period. These adaptations are accompanied by changes in the Hypothalamus-Pituitary-Adrenal Axis (HPAA), energy metabolism, and the cardiovascular system. Premature birth, failure of transfer of passive immunity, and infections often result in foal sepsis and death. Critically ill foals are sent to intensive care units with hypotension, poor tissue perfusion, energy dysregulation, acid-base and electrolyte abnormalities, and organ failure. Survival under these circumstances is dictated by the ability of various homeostatic systems to overcome these derangements and control systemic inflammation. Unfortunately, a number of these foals remain refractory to current therapies and succumb to sepsis, likely the result of endocrine failure, which our group has shown to be associated with foal mortality.
In response to stress, the hypothalamus releases corticotropin-releasing hormone (CRH) and vasopressin (AVP) to stimulate the pituitary gland to secret adrenocorticotropic hormone (ACTH), which induces the adrenal cortex to release cortisol, aldosterone, and sex steroids. Except for cortisol, information on adrenocortical function in sick foals is limited. We, and others, have shown that in most critically ill foals, HPAA activation is characterized by increased AVP, ACTH and cortisol concentrations. However, the role of hypothalamic or pituitary failure in adrenal insufficiency (AI) in sick newborn foals remains unclear.
A major complication of sepsis in children is relative adrenal insufficiency (RAI) or critical illness- related corticosteroid insufficiency (CIRCI), in which the secretion of one or multiple adrenocortical steroids is impaired and contributes to mortality. In people, adrenal gland function is not evaluated only by measuring cortisol and the response to ACTH stimulation, but also other adrenal steroids including dehydroepiandrosterone (DHEA), aldosterone, corticosterone, and androstenedione.6 In equine practice, the evaluation of adrenal gland function is limited to cortisol concentrations, and ACTH stimulation tests are rarely performed. Drs. Aleman and Madigan have provided persuasive evidence that progestagens affect newborn foal behavior and may be involved in the pathogenesis of maladjustment syndrome.
HPAA dysfunction in septic foals occurs primarily at the adrenal gland level; however, based on work by our group, hyposecretion of hypothalamic (CRH, AVP) and pituitary factors (ACTH) likely contributes to this process. Endocrine factors that regulate hypothalamic function in other species include brain derived neurotrophic factor (BDNF), endocannabinoids, cytokines, LPS, NMDAR (N-methyl-D-aspartate receptor), and GABAAR (GABAA receptor).10 BDNF is a key modulatory factor for CRH and AVP secretion. Low BDNF levels were associated with mortality in critically ill human patients.11 In our pilot data we found a trend for low BDNF levels in 8 septic foals. Relevant to this proposal, adrenal steroids (DHEA, progesterone, pregnenolone) can be transformed into neurosteroids (allopregnanolone), which provide neuroprotection by inhibiting NMDAR, stimulating GABAAR, modulating BDNF, and promoting CRH and AVP secretion. We propose that BDNF is a key player in hypothalamic dysfunction in septic foals. We also suggest that inappropriate neurosteroid secretion will be linked to low BDNF levels in septic foals with HP dysfunction. Thus, the overall goal of this project is to elucidate the role of hypothalamic regulatory factors (e.g. BDNF) and their interaction with adrenal steroid precursors / neurosteroids in the development of RAI in critically ill foals.
We hypothesize that while in critically ill foals AI is mainly the result of adrenal failure (primary RAI), in a number of foals impaired secretion of steroid precursors/neurosteroids and BDNF leads to hypothalamic (tertiary RAI; ↓AVP, ↓CRH) and subsequently pituitary (secondary RAI; ↓ACTH) and adrenal gland dysfunction, which will be associated with multiple clinical derangements and a worse prognosis for survival.
This study will show that in addition to its effects on metabolic and immune functions (↓cortisol), RAI can also lead to electrolyte and fluid dysregulation, , delayed organ maturation, and neurological abnormalities. This information will have prognostic and therapeutic value. A comprehensive understanding on the HPAA response to sepsis will provide the opportunity for the development of novel therapies for equine neonatal sepsis. For example, the use of neurosteroids to modulate HPAA function may have potential use in the clinic.