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Coverage of the Merial Raceday - York 2017

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Over 40 vets from around the UK attended the continuing professional development event titled ‘How to optimise the respiratory effects on performance’ at York Racecourse this May. The event, organised by European Trainer Magazine and Merial Animal Health, featured a panel of expert speakers and was co-sponsored by Connolly’s RED MILLS & Foran Equine and Haygain. Louise Jones BSc, MSc attended the seminar and reports on the key messages as follows. Functional Significance of Upper Airway Obstructions - Dr Kate Allen Dr Kate Allen, from Langford Vets, commenced proceedings, explaining that whilst upper airway obstruction (UAO) is second to lameness as the most common cause of poor performance, it is difficult to quantify its significance on athletic performance. UAO is caused by a narrowing of the airways, often as a result of the collapse of the varying upper airway structures. However, Dr Allen emphasised that it is a complex condition and in almost half of the cases involves the concurrent collapse of multiple structures. Horses suffering from UAO initially attempt to maintain airflow by increasing inspiration time and decreasing respiratory frequency. However, if this is unsuccessful then the amount of oxygen available for the muscles to work effectively will be reduced, resulting in impaired performance. The degree to which athletic performance is affected, especially in the elite horse, will obviously depend on several factors, including:  The severity and complexity of the condition: palatal instability alone will only have a mild effect on performance, but when occurring in conjunction with dorsal displacement of the soft palate (DDSP) the impact will be significantly greater.  The duration of time the obstruction is present within a bout of exercise: DDSP at the end of a race is likely to be less performance limiting than if it occurs during the early stages.  The work the horse is undertaking: arytenoid cartilage collapse (ACC) at low exercise intensity does not significantly impact respiratory frequency, but at higher intensity exercise ACC will reduce respiratory frequency.  Individual variation: the effect of DDSP on oxygen consumption can vary from as little as 0.1% up to 15% depending on the individual. Dr Allen went on to examine the possible link between UAO, exercise induced pulmonary haemorrhage (EIPH) and inflammatory airway disease (IAD). She stressed that whilst there is good scientific rational suggesting that UAO may exacerbate EIPH by further increasing pressure differences between the inside of the capillary and the alveolar, at present there is limited clinical data to support the theory. Likewise, there is minimal evidence to link UAO and lower airway disease, although there have been occasional examples where treatment for lower airway disease results in a reduction of abnormal respiratory noise. Dr Allen stated ‘the winning horse is the one that slows the least’ and described how making a 1% improvement to a horse finishing in fourth place would mean that they should then go on to win 50-75% of the time, in national hunt and flat racing respectively. Dr Allen warned that any UAO in the racehorses is likely to have a detrimental impact on performance. She also advised that the effects of certain conditions such as pharyngeal wall collapse and severe medial deviation of the aryepiglottic folds may currently be underestimated. Dr Allen concluded that whilst treatments for UAO may reduce the issue, unfortunately they are not always effective in restoring the horse’s full respiratory capacity. Key Aspects of Infectious Respiratory Disease - Professor Andy Durham Professor Andy Durham, from Liphook Equine Hospital, discussed bacterial and viral causes of respiratory disease in horses. He provided the veterinarians with a detailed review of the various diagnostic tools available including visual assessment of the airways, bacteriology and haematology, particularly emphasising the usefulness of testing serum iron levels as a marker of inflammation. Professor Durham went on to question the clinical relevance of bacteria isolated from the nasal swabs and tracheal washes. He recommends that bacteria isolated from nasal swabs should not be regarded with pathologic relevance, unless accompanied by abnormal mucus, squamous epithelial cells and/ or greater than 20% neutrophils. In addition, he highlighted that evidence of bacteria from tracheal washes is often not pathologically relevant and must be interpreted with caution. The potential for contamination during the scoping procedure is a major confounding factor. Referring to cases of strangles, Professor Durham expressed the view that using nasopharyngeal swabs to test for carriers is unreliable, even when these tests are repeated. Therefore, he recommends guttural pouch lavage as a far superior method of identify carriers of Streptococcus equi. There are several viruses that can cause infection of the airways, potentially predisposing the horse to inflammatory airway disease (IAD) including picornaviruses, herpesviruses and equine influenza virus. Picornaviruses, include equine rhinitis virus A (ERAV) and equine rhinitis B (ERBV), cause mild respiratory infection in horses, similar to the common cold brought about by rhinoviruses in humans. Although a significant association between IAD and seropositivity to ERAV has been confirmed, the importance and role of equine rhinitis viruses in poor performance remains unclear. Professor Durham questioned the sensitivity of the equine rhinitis virus A and B blood test. He expressed surprise that only one out of 607 samples tested at the Animal Health Trust last year was positive, even though subclinical infections are relatively common. Of the herpesviruses known to infect horses EHV-1 and EHV-4 are the two that result in acute respiratory infection. The relevance of EHV-2 and EHV-5 is less clear and Professor Durham stressed that positive EHV-2 blood tests must be interpreted cautiously as they may be indicative of previous exposure to the virus, rather than current disease. He advised that nasal swabs may be more useful than serology as a diagnostic technique, highlighted that EHV-2 has been isolated from the nasal swabs of horses suffering from IAD, suggesting that it could play a role in aggravating the airways. Professor Durham next discussed equine influenza. He explained that the equine influenza A virus (H3N8) is diverged into two different strains - the European strain and the American strain. The latter is further divided into the Kentucky strain and the Florida strains; clade 1 and clade 2. Drawing attention to a recent outbreak in the north of England, Professor Durham stressed that equine flu caused by the Florida clade 2 virus, remains a threat in the UK. He also warned that horses that are exposed to internationally travel should be vaccinated against the Florida clade 1 virus, which has been detected in the USA. Professor Durham concluded his presentation by questioning the efficacy of many of the equine influenza vaccines currently used in the UK, emphasising that only one, Merial’s Proteq-flu, is effective against both clade 1 and 2 of the Florida sublineage. Managing Inflammatory Disease - Dr Emmanuelle van Erck The importance of the horse’s environment on respiratory health cannot be overlooked. It is unavoidable that horses in training are housed indoors for much of their day, resulting in increased exposure to respirable dust, ammonia and mould. Consequently, these horses will be at increases risk of IAD, although this may not always manifest itself as a clear respiratory problem. Often the clinical symptoms of chronic respiratory issues can be subtle but may include early fatigue, reduced recovery and an unwillingness to work. According to Dr Emmanuelle van Erck’s own research 84% of the horses referred to a veterinarian for a regular health check, poor performance or respiratory issues were suffering from IAD and she firmly believes that managing the horse’s environment carefully is the ‘key to long-term management of IAD cases’. Dr van Erck explained the crucial importance of stable design in facilitating correct ventilation, controlling humidity and limiting exposure to potential noxious elements. She discouraged the use of ventilators and fans, which simply exacerbate the dissemination of dust and mound spores. Likewise, she highlighted the risk of storing preserved forage and bedding material within the stable building. To reduce the respiratory challenges encountered by stabled horses, Dr van Erck also recommends that they are turned out when activities such as mucking out or sweeping are taking place. She went on to explain that temperature within the stable environment is also important, advising that horses are most comfortable at temperatures around 10 o C. She warned that our tendency to close windows and doors during cold weather can create the warm, humid environment favoured by harmful microorganisms. When considering bedding material, although straw has several benefits, Dr van Erck reiterated that it can be naturally contaminated with mould and fungi. Inhalation of these microorganisms can impact respiratory health and research that has shown horses are 3.8 times greater chance of being diagnosed with IAD if fungi were found in their airways. Paper or cardboard bedding material, which are lower in dust and other aeroallergens, are preferred by Dr van Erck. Alternatively, she encourages the use of dust-free wood shavings, provided the flake size and thickness is adequate. Another option is to use rubber matting, although this must be kept clean in order to avoid fungal growth. Forage, particularly hay, is another major source of dust and contaminants which can contribute to IAD. To reduce this risk Dr van Erck prefers horses to be fed either commercially grown, quality controlled haylage or steamed hay. She explained that soaking hay, although economical, is not advisable and could, in fact, create an environment for bacteria to proliferate. Similarly, Dr van Erck warned against using home-made hay steamers, which may not homogenously heat the hay to the temperatures needed to destroy bacteria and mould, and therefore could exacerbate the issue by creating the ideal environment required for microbial incubation. Instead Dr van Erck advised steaming hay, using a Haygain steamer, immediately prior to feeding. She described that the heat generated in this commercially available steamer will kill the bacteria and reduce the respirable particles by more than 95%, without affecting the nutritional value of the hay. This offers trainers a practical way of providing their horses with clean forage and thereby helping to significantly decreased the risk of IAD. Optimising Oxygen Uptake and Lung Function - Dr Shaun McKane In the world of racing ‘time is money’ said Dr Shaun McKane, from Cotts Equine Hospital & Veterinary Specialists. He went on to use the one inch winning margin of Neptune Collonges over rival Sunnyhillboy in the 2012 Grand National to emphasise that oxygen is the key in making the horse the ultimate athlete and ‘every molecule of oxygen is important’. Dr McKane explained that relative to other species, horses have 2.5 times more lung surface area and almost 20 times greater cardiac output than humans. In addition, splenic contraction during exercise means that the horse have the ability to increase the volume of circulating red blood cell volume by as much as 65%, resulting in a doubling of their oxygen carrying capacity. Dr McKane asked the question – ‘what makes the average horse average?’ The answer - lack of ability, inadequate training and/or a reduction in their maximum oxygen uptake, scientifically referred to as VO2 max. Discussing the importance of optimal training Dr McKane explained that if you train sub-maximally, you will perform sub-maximally. Regular, lengthy aerobic exercise will help to condition the horse by increasing mitochondria numbers and muscle capillary density. However, this type of training will not be sufficient to optimise the horses VO2 max, which is a high indicator of athletic potential and has been found to be highly correlated with race times in thoroughbred horses. To achieve optimal VO2 max, high intensity ‘interval training’ is essential, plus this type of training will also condition both the bones and tendons. Dr McKane went on to discuss the potential detrimental impact of airway inflammation and EIPH on athletic performance. He reiterated that whilst inflammation can promote EIPH it doesn’t necessarily cause it. Nevertheless, he advises that care should be taken when recommending exercise for horses suspected to be suffering from pulmonary inflammatory disease as they may be at greater risk of EIPH. Discussing the effect of EIPH on performance Dr McKane highlighted that the degree of EIPH should be considered. He explained that mild bleeding (grade 1-2 EIPH) will not affect performance, although more severe bleeding (grade 3-4) will reduce athletic ability. Dr McKane recommended routine monitoring of racehorses for signs of airway dysfunction by regularly carrying out cytologic evaluation of tracheal washes or bronchoalveolar lavages. Carrying out these evaluations close to a race will obviously be helpful in determining if the horse is ‘fit to race’ but Dr McKane’s preference would be to undertake these tests 10 days pre-race, thus allowing sufficient time for steroid treatment and an adequate withdrawal period. He also encouraged the use of pre-emptive testing on horses that are considered to be performing well. In addition, Dr McKane highlighted that whilst resting horses suffering from EIPH may be appropriate, extended periods off work (e.g. 3 weeks) would result in fitness returning to basal levels. Finally, Dr McKane touched on seasonal aspects of respiratory issues, explaining that he has observed an increase in issues around February-March, which could potentially be associated with an increase in fungal growth as a result of warmer weather conditions. Another high risk period is March-May, which may be linked to an increase in tree and rapeseed pollen as a similar pattern is observed in humans suffering from asthma. Assessment of a novel antioxidant supplement for Thoroughbred horses in training - optimising and protecting cells through nutrition - Maureen Dowling Maureen Dowling from the School of Veterinary Medicine, University College Dublin (UCD), summarised her research about using a natural antioxidant and fish oil supplement on horses in training. She explained that oxidation is simply the production of volatile free radical atoms and is a completely natural process necessary for all biological pathways. Oxidation can become detrimental to horses when the antioxidant/oxidant equilibrium changes in favour of oxidants, otherwise known as free radicals. She explained that horses have endogenous antioxidants, which can normally control oxidant production, however when a stress factor is introduced, such as exercise, respiratory or inflammation response problems can arise. Free radicals will bind onto the membranes of cells causing erosion to the membrane, leading to cell necrosis and ultimately tissue damage. Antioxidants prevent this damage by binding to the oxidant before it gets to the cell or within the cell. Natural sources of antioxidants such as bioflavonoids allow for immediately available antioxidant properties. Maureen Dowling described how unfit or pre-trained horses are more susceptible to muscle cell breakdown. In her research Dowling has shown that supplementation with a natural antioxidant and fish oil supplement prior to and throughout the training process allows a build-up of antioxidant protection before cells are affected. The research carried out in UCD showed a significant reduction of creatine kinase (CK) levels in horses receiving the supplement during the training regime. In addition, following 12 weeks of supplementation, horses had higher levels of α-tocopherol than those not supplemented. Plus, following a maximum intensity treadmill exercise after 12 weeks of training, horses who didn’t receive the supplement had significantly higher levels of oxidation in their blood than those that were on the supplement. Unsurprisingly, give the calibre and expertise of all the speakers the seminar was a great success and instigated numerous questions and discussions amongst the veterinarians in attendance.

First published in European Trainer issue 58 - July - September 2017

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Over 40 vets from around the UK attended the continuing professional development event titled ‘How to optimise the respiratory effects on performance’ at York Racecourse this May. The event, organised by European Trainer Magazine and Merial Animal Health, featured a panel of expert speakers and was co-sponsored by Connolly’s RED MILLS and Haygain. Louise Jones BSc, MSc attended the seminar and reports on the key messages as follows.

Functional Significance of Upper Airway Obstructions - Dr Kate Allen

Dr Kate Allen, from Langford Vets, commenced proceedings, explaining that whilst upper airway obstruction (UAO) is second to lameness as the most common cause of poor performance, it is difficult to quantify its significance on athletic performance.  

UAO is caused by a narrowing of the airways, often as a result of the collapse of the varying upper airway structures. However, Dr Allen emphasised that it is a complex condition and in almost half of the cases involves the concurrent collapse of multiple structures.

Horses suffering from UAO initially attempt to maintain airflow by increasing inspiration time and decreasing respiratory frequency. However, if this is unsuccessful then the amount of oxygen available for the muscles to work effectively will be reduced, resulting in impaired performance. The degree to which athletic performance is affected, especially in the elite horse, will obviously depend on several factors, including....

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