Evaluation of the diagnostic accuracy of skeletal scintigraphy in lame and poorly performing sports horses.

Skeletal scintigraphy is an established imaging modality, however, its validity as a diagnostic test in lame or poorly performing sports horses has not been determined. The objective of this retrospective cross-sectional analytical study was to determine the accuracy of skeletal scintigraphy as an indiscriminate screening test in sports horses. All sports horses that underwent scintigraphic examination between March 2008 and December 2014 for which a definitive diagnosis was reached were included. Examinations were evaluated blindly. Characteristics of increased radiopharmaceutical uptake were recorded and subjectively categorized as possibly relevant or non-relevant. Kappa statistics were used to assess agreement between test results and final diagnosis. There were 1222 positive clinical diagnoses in 480 horses, of which 687 regions (56.4%) had no associated increased radiopharmaceutical uptake and 99 regions (8.1%) had non-relevant increased radiopharmaceutical uptake. The sensitivity of increased radiopharmaceutical uptake for identification of final diagnosis was low (43.8%) and specificity was high (94.0%). The agreement was fair (κ = 0.36). Relevance categorization improved the test; the sensitivity for final diagnosis was low (35.7%), specificity was high (98.9%), and the agreement was moderate (κ = 0.45). The agreements of increased radiopharmaceutical uptake and relevance categorization with final diagnosis were only substantial for feet (κ = 0.67 and κ = 0.66, respectively) and proximal aspect of the forelimb (elbow, shoulder, and scapula combined) (κ = 0.69 and 0.78, respectively). Scintigraphic examination is unlikely to lead to a full and correct diagnosis of the cause(s) of lameness or poor performance in sports horses when used as an isolated or indiscriminate screening tool.

Evaluation of the diagnostic accuracy of skeletal scintigraphy for the causes of front foot pain determined by magnetic resonance imaging.

There is good correlation between increased radiopharmaceutical uptake anywhere in the feet of sports or leisure horses and the presence of foot pain. However, low sensitivity of scintigraphy for identifying lesions contributing to foot pain as determined by magnetic resonance imaging (MRI) has been reported. The aim of this retrospective, cross-sectional, analytical study was to assess the accuracy of scintigraphy for identifying the cause(s) of foot pain, using MRI as the reference standard. Sports and leisure horses that underwent both skeletal scintigraphy and MRI of the front feet between March 2008 and December 2014 and for which a definitive diagnosis of the cause(s) of front foot pain was reached were included (121 feet of 70 horses). Imaging studies were evaluated retrospectively, blindly. Agreements between scintigraphic localization of increased radiopharmaceutical uptake and subjective categorization of lesions with MRI diagnosis were assessed using Kappa statistics (κ). Measures of diagnostic accuracy were calculated. Sensitivity of increased radiopharmaceutical uptake varied among regions (31.8-76.2%) but specificity was at least high for all (84.6-100%). Agreements between both scintigraphy measures and MRI diagnosis were substantial for the distal phalanx (palmar processes and body) (κ = 0.77 and κ = 0.74, respectively), and ungular cartilages and chondral ligaments (κ = 0.62, for both). When all regions were combined, agreements of increased radiopharmaceutical uptake (κ = 0.49) and relevance categorization (κ = 0.45) with MRI diagnosis were moderate. In conclusion, skeletal scintigraphy does not meet the minimum reliability level for a diagnostic test, but is reliable for identification of osseous trauma to the distal phalanx and ungular cartilages.

Demographics, Management, Preventive Health Care and Disease in Aged Horses.

Gerontology has become increasingly important in equine veterinary medicine, with aged animals representing a significant proportion of the equine population. Horses are defined as geriatric or aged from age 15 years onwards but can have a life span of more than 40 years. Despite a high level of owner concern for the well-being of their geriatric animal, provision of preventive health care may be suboptimal. Owners seem to under-recognize some of the most prevalent diseases identified in geriatric horses. This review focuses on the demographic characteristics of the equine geriatric population and management and preventive care practices of older horses.

Welfare, Quality of Life, and Euthanasia of Aged Horses.

Duration of ownership strengthens the human-horse bond, affecting decision-making about the horse's welfare, quality of life (QoL), and euthanasia. Most owners consider their geriatric horses to have good or excellent QoL; however, increasing age is negatively associated with QoL. Management factors are important. The most common reasons for euthanasia include musculoskeletal disorders or lameness, colic, and nonspecific chronic diseases. The decision to euthanize is difficult, so the advice of the veterinarian and QoL are important. This article focuses on the human-horse bond, assessment of QoL, reasons for euthanasia, and owner experiences of mortality.

Unilateral laser ventriculocordectomy results in increased arytenoid stability in horses with severe left sided recurrent laryngeal neuropathy.

BACKGROUND: There is no objective information reporting the effect of unilateral laser ventriculocordectomy (VeC) on arytenoid abduction or stability. OBJECTIVES: To evaluate arytenoid stability and abduction in horses with severe recurrent laryngeal neuropathy (RLN) before and after unilateral laser VeC. STUDY DESIGN: Prospective cohort. METHODS: Eight horses with grade C or D exercising laryngeal function that underwent unilateral laser VeC were included. Exercising endoscopy was performed before and ≥6 weeks after left-sided laser VeC. Arytenoid stability at maximal exercise was calculated by measuring the left-to-right quotient angle ratio (LRQ) of the corniculate processes at the points of maximal arytenoid abduction (expiration) and maximal arytenoid collapse (inspiration). For each horse, means of measurements obtained for four breaths pre- and post-operatively were used for statistical analysis. RESULTS: The difference in LRQ between inspiration and expiration was lower post-operatively (median 0.039; interquartile range [IQR] 0.032-0.047) compared with pre-operatively (median 0.158; IQR 0.083-0.249; p = 0.01) confirming the left arytenoid was more stable following unilateral laser VeC. The degree of improvement was significantly greater for grade D horses compared with grade C horses (p = 0.04). The LRQ measured on maximal abduction was also lower post-operatively (median 0.467; IQR 0.444-0.506) compared with pre-operatively (median 0.578; IQR 0.554-0.655; p = 0.02) indicating the left arytenoid was less abducted following surgery. MAIN LIMITATIONS: The sample size was small, no racehorses were included and post-operative assessment was conducted at a variable time after surgery. CONCLUSION: Unilateral laser VeC in grade C and D RLN-affected horses results in slightly reduced left arytenoid abduction but increased arytenoid stability.

BEVA primary care clinical guidelines: Diagnosis and management of equine pituitary pars intermedia dysfunction.

BACKGROUND: Pituitary pars intermedia dysfunction (PPID) is a prevalent, age-related chronic disorder in equids. Diagnosis of PPID can be challenging because of its broad spectrum of clinical presentations and disparate published diagnostic criteria, and there are limited available treatment options. OBJECTIVES: To develop evidence-based primary care guidelines for the diagnosis and treatment of equine PPID based on the available literature. STUDY DESIGN: Evidence-based clinical guideline using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) framework. METHODS: Research questions were proposed by a panel of veterinarians and developed into PICO or another structured format. VetSRev and Veterinary Evidence were searched for evidence summaries, and systematic searches of the NCBI PubMed and CAB Direct databases were conducted using keyword searches in July 2022 and updated in January 2023. The evidence was evaluated using the GRADE framework. RESULTS AND RECOMMENDATIONS: The research questions were categorised into four areas: (A) Case selection for diagnostic testing, pre-test probability and diagnostic test accuracy, (B) interpretation of test results, (C) pharmacological treatments and other treatment/management options and (D) monitoring treated cases. Relevant veterinary publications were identified and assessed using the GRADE criteria. The results were developed into recommendations: (A) Case selection for diagnostic testing and diagnostic test accuracy: (i) The prevalence of PPID in equids aged ≥15 years is between 21% and 27%; (ii) hypertrichosis or delayed/incomplete hair coat shedding provides a high index of clinical suspicion for PPID; (iii) the combination of clinical signs and age informs the index of clinical suspicion prior to diagnostic testing; (iv) estimated pre-test probability of PPID should be considered in interpretation of diagnostic test results; (v) pre-test probability of PPID is low in equids aged <10 years; (vi) both pre-test probability of disease and season of testing have strong influence on the ability to diagnose PPID using basal adrenocorticotropic hormone (ACTH) or ACTH after thyrotropin-releasing hormone (TRH) stimulation. The overall diagnostic accuracy of basal ACTH concentrations for diagnosing PPID ranged between 88% and 92% in the autumn and 70% and 86% in the non-autumn, depending on the pre-test probability. Based on a single study, the overall diagnostic accuracy of ACTH concentrations in response to TRH after 30 minutes for diagnosing PPID ranged between 92% and 98% in the autumn and 90% and 94% in the non-autumn, depending on the pre-test probability. Thus, it should be remembered that the risk of a false positive result increases in situations where there is a low pre-test probability, which could mean that treatment is initiated for PPID without checking for a more likely alternative diagnosis. This could compromise horse welfare due to the commencement of lifelong therapy and/or failing to identify and treat an alternative potentially life-threatening condition. (B) Interpretation of diagnostic tests: (i) There is a significant effect of breed on plasma ACTH concentration, particularly in the autumn with markedly higher ACTH concentrations in some but not all 'thrifty' breeds; (ii) basal and/or post-TRH ACTH concentrations may also be affected by latitude/location, diet/feeding, coat colour, critical illness and trailer transport; (iii) mild pain is unlikely to have a large effect on basal ACTH, but caution may be required for more severe pain; (iv) determining diagnostic thresholds that allow for all possible contributory factors is not practical; therefore, the use of equivocal ranges is supported; (v) dynamic insulin testing and TRH stimulation testing may be combined, but TRH stimulation testing should not immediately follow an oral sugar test; (vi) equids with PPID and hyperinsulinaemia appear to be at higher risk of laminitis, but ACTH is not an independent predictor of laminitis risk. (C) Pharmacologic treatments and other treatment/management options: (i) Pergolide improves most clinical signs associated with PPID in the majority of affected animals; (ii) Pergolide treatment lowers basal ACTH concentrations and improves the ACTH response to TRH in many animals, but measures of insulin dysregulation (ID) are not altered in most cases; (iii) chasteberry has no effect on ACTH concentrations and there is no benefit to adding chasteberry to pergolide therapy; (iv) combination of cyproheptadine with pergolide is not superior to pergolide alone; (v) there is no evidence that pergolide has adverse cardiac effects in horses; (vi) Pergolide does not affect insulin sensitivity. (D) Monitoring pergolide-treated cases: (i) Hormone assays provide a crude indication of pituitary control in response to pergolide therapy, however it is unknown whether monitoring of ACTH concentrations and titrating of pergolide doses accordingly is associated with improved endocrinological or clinical outcome; (ii) it is unknown whether monitoring the ACTH response to TRH or clinical signs is associated with an improved outcome; (iii) there is very weak evidence to suggest that increasing pergolide dose in autumn months may be beneficial; (iv) there is little advantage in waiting for more than a month to perform follow-up endocrine testing following initiation of pergolide therapy; there may be merit in performing repeat tests sooner; (v) timing of sampling in relation to pergolide dosing does not confound measurement of ACTH concentration; (vi) there is no evidence that making changes after interpretation of ACTH concentrations measured at certain times of the year is associated with improved outcomes; (vii) evidence is very limited, however, compliance with PPID treatment appears to be poor and it is unclear whether this influences clinical outcome; (viii) evidence is very limited, but horses with clinical signs of PPID are likely to shed more nematode eggs than horses without clinical signs of PPID; it is unclear whether this results in an increased risk of parasitic disease or whether there is a need for more frequent assessment of faecal worm egg counts. MAIN LIMITATIONS: Limited relevant publications in the veterinary scientific literature. CONCLUSIONS: These findings should be used to inform decision-making in equine primary care practice.

Equine Endocrine Disease: Challenges With Case Definition for Research.

Equine endocrine disease is an important area for equine research, requiring an appropriate case definition for inclusion and criteria for exclusion from disease. Defining a case for research may be different from criteria for clinical diagnosis. Further, clinical diagnosis recommendations have been changing regularly, making this area challenging for equine scientists. This review discusses the diagnosis of major equine endocrine diseases, pituitary pars intermedia dysfunction, equine metabolic syndrome and insulin dysregulation, focusing on the most appropriate diagnostic methods for research case definitions. Different diagnostic methods, including use of reference intervals and clinical decision limits, will be discussed with their relative merits for use in case definition for research.

Risk factors for a first episode of primary uveitis in the UK and proportion of cases that experience recurrence following this first episode.

BACKGROUND: Risk factors for a first episode of primary uveitis in horses have not been determined. In addition, disease progression and the proportion of horses that develop recurrence following the original episode are not known. OBJECTIVES: To determine the risk factors for the development of a first episode of primary uveitis in horses in the UK and to document the proportion of cases that experience recurrence following this first episode. STUDY DESIGN: Prospective case-control longitudinal study. METHODS: Horses with a first episode of primary uveitis between July 2014 and August 2018 were recruited to the study. For each case, two controls were selected. A questionnaire was completed for each horse and multivariable logistic regression analysis was carried out to identify associations between horse and management-level variables and the risk of uveitis. Each case was then followed longitudinally to determine the rate of recurrence of uveitis. RESULTS: Twenty-three cases and 46 controls were recruited. Being close to a pig farm (OR 27.8, CI 1.31-592.06) and a recent history of flooding of the pasture (OR 15.43, CI 2.80-84.98) was associated with increased risk of uveitis. Being in the same owner's possession for a longer amount of time had a protective effect (OR 0.79, CI 0.68-0.93). Horses recovered uneventfully following treatment and showed no evidence of recurrence in 59.1% of the cases (n = 13). In five horses (22.7%), the initial episode of uveitis could not be controlled and required surgical therapy. Recurrence was observed in four horses (18.2%). MAIN LIMITATIONS: Small sample size. Recall bias from owners for some of the data. Possibility of selection bias. CONCLUSIONS: Clinicians can use this information to identify horses with increased risk of uveitis and provide advice to the owners of these horses. The proportion of cases that experience recurrence appears low in the UK.

Diagnosis of equine pituitary pars intermedia dysfunction.

Equine pituitary pars intermedia dysfunction (PPID) is common in aged horses. The majority of horses respond well to treatment, but treatment is lifelong, meaning accurate diagnosis of PPID is important. Similar to any condition, there is no perfect laboratory test to diagnose PPID and accuracy is affected by the characteristics of the population in which the test is being evaluated. This review details the importance of consideration of clinical factors and diagnostic test accuracy. Basal adrenocorticotrophic hormone (ACTH) concentration is used most frequently in practice and has very good diagnostic accuracy when used in combination with clinical judgement and the correct application of diagnostic thresholds. The thyrotropin-releasing hormone stimulation test can be used in horses with equivocal test results following basal ACTH testing, or to evaluate subtle cases due to its improved accuracy.

Approaches to endocrinopathic laminitis in the field: Results of a survey of veterinary practitioners in North America.

Endocrinopathic laminitis is the most common cause of laminitis in the field. Insulin has recently been implicated as a key factor in development of endocrinopathic laminitis; however, it is unclear whether diagnostic, and treatment approaches reflect insights derived from recent research. This study sought to evaluate North American veterinary practitioners' approach to endocrinopathic laminitis in the field. Demographic information, approach to diagnosis, management, and prognosis of endocrinopathic laminitis, as well as factors influencing changes in approach to laminitis were collected. To compare regional differences in approach to laminitis, results were compared to a recently published study from the United Kingdom. Findings of the present study suggest that North American practitioners have changed their approach to laminitis to more readily incorporate diagnostic testing for endocrine disease.

Equine pituitary pars intermedia dysfunction: Identifying research priorities for diagnosis, treatment and prognosis through a priority setting partnership.

Pituitary pars intermedia dysfunction (PPID) is the most prevalent endocrine disorder of older equids. To date, key research areas likely to have the greatest impact on equine health have not been identified. In human medicine, public and patient involvement is widely used to inform research agendas. This study aimed to engage with veterinary surgeons and horse owners to identify evidence gaps ('uncertainties') and prioritise these into a list of the 10 most important PPID research questions. The James Lind Alliance (JLA) Priority Setting Partnership (PSP) Framework was adapted. Questions about the diagnosis, treatment and prognosis of PPID were gathered via an online survey targeting veterinary surgeons and horse owners with experience of PPID. Thematic analysis was used to form a longlist of collated indicative research questions (CIRQs), defined by the JLA as true 'evidence uncertainties' when not answered by a published, clinically relevant, up-to-date systematic review. In an interim prioritisation survey, questions were ranked by weighted scores creating a shortlist of 25 that were taken forward to the PSP workshop, where participants reached a consensus on the top 10. Useable responses containing ≥1 question were received from 524 respondents (92.6% owners, n = 485; 7.4% veterinary surgeons, n = 39). After screening for relevance, 1,260 individual questions were included in thematic analysis, resulting in 47 CIRQs. Interim prioritisation votes for the CIRQs were received from 360 respondents. The top 10 questions prioritised at the PSP workshop focused on long-term prognosis, diagnostic accuracy, efficacy of pergolide treatment, alternative treatment/management strategies and potential treatment options for poor responders to pergolide. The quantity of questions generated indicates an extensive number of uncertainties regarding the diagnosis, treatment and prognosis of PPID. The top 10 research questions will help to inform key areas for evidence synthesis and knowledge translation, and to direct future research into areas most important to end users involved in caring for and treating animals with PPID.

Relationships of inflamm-aging with circulating nutrient levels, body composition, age, and pituitary pars intermedia dysfunction in a senior horse population.

Similarly to aged humans, senior horses (≥20 years) exhibit chronic low-grade inflammation systemically, known as inflamm-aging. Inflamm-aging in the senior horse has been characterized by increased circulating inflammatory cytokines as well as increased inflammatory cytokine production by lymphocytes and monocytes in response to a mitogen. Little is currently known regarding underlying causes of inflamm-aging. However, senior horses are also known to present with muscle wasting and often the endocrinopathy pituitary pars intermedia dysfunction (PPID). Despite the concurrence of these phenomena, the relationships inflamm-aging may have with measures of body composition and pituitary function in the horse remain unknown. Furthermore, nutrition has been a focus of research in an attempt to promote health span as well as life span in senior horses, with some nutrients, such as omega-3 fatty acids, having known anti-inflammatory effects. Thus, an exploratory study of a population of n = 42 similarly-managed senior horses was conducted to determine relationships between inflamm-aging and measures of circulating nutrients, body composition, age, and PPID. Serum was collected to determine vitamin, mineral, and fatty acid content. Peripheral blood mononuclear cells were also isolated to determine inflammatory cytokine production of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) following stimulation with a mitogen, as well as to determine gene expression of interleukin(IL)-1ß, IL-6, IL-10, IFN-γ, and TNF-α. Serum IL-6 and C-reactive protein were determined by enzyme-linked immunosorbent assay. Whole blood was collected for hematological and biochemical analysis. Body composition was evaluated via ultrasound and muscle scoring for all 42 horses as well as by deuterium oxide dilution for a subset of n = 10 horses. Pituitary function was evaluated by measuring basal adrenocorticotropin hormone concentrations as well as by thyrotropin releasing hormone stimulation testing (to determine PPID status). Results showed various relationships between inflammatory markers and the other variables measured. Most notably, docosadienoic acid (C22:2n6c), docosapentaenoic acid (C22:5n3c), and folate were positively associated with numerous inflammatory parameters (P ≤ 0.05). Although no relationships were found between inflamm-aging and PPID, being positive for PPID was negatively associated with vitamin B12 (P ≤ 0.01). No relationships between inflammation and body composition were found. Even within this senior horse population, age was associated with multiple parameters, particularly with numerous inflammatory cytokines and fatty acids. In summary, inflamm-aging exhibited relationships with various other parameters examined, particularly with certain fatty acids. This exploratory study provides insights into physiological changes associated with inflamm-aging in the senior horse.

Designing a field trial of an equine grass sickness vaccine: A questionnaire-based feasibility study.

Without an experimental model of equine grass sickness (EGS), a randomised controlled field trial (RCT) represents the only method of evaluating the efficacy of Clostridium botulinum type C vaccination in preventing naturally occurring disease. Clinical trial feasibility is an important aspect of preliminary work undertaken prior to initiating RCTs, estimating parameters that are important for study design. This cross-sectional study aimed to assess the feasibility of conducting a nationwide RCT of a candidate vaccine for EGS based on responses from a sample of British equine veterinary practices (n = 119/284). Seventy-three percent of practices had attended ≥1 EGS case within the preceding 2 years (median four cases), and 51.3% regularly attended recurrently affected premises. Veterinary surgeons had greater confidence diagnosing acute/subacute EGS based solely on history and clinical signs compared to chronic EGS. Ninety-one percent of respondents (n = 103/113) considered the proposed RCT to be important/very important to equine veterinary research. Ninety-one percent of respondents (n = 102/112) indicated preparedness to assist in owner recruitment and 92.9% (n = 104/112) indicated willingness to participate in a RCT. The most frequent reasons for practices declining to participate were low incidence of EGS (n = 4), did not believe clients would wish to participate (n = 3) and amount of paperwork/data collection involved (n = 2). There was considerable support amongst participating veterinary practices for a RCT evaluating the efficacy of Clostridium botulinum vaccination for the prevention of EGS in Britain. Substantial proportions of participating practices would be prepared to participate in the RCT and regularly attended EGS-affected premises that would meet trial inclusion criteria.

A survey of health care and disease in geriatric horses aged 30 years or older.

This study reports on aspects of preventive health care and on the prevalence of disease in geriatric (≥30 years old) horses and ponies in North-West England and North Wales. Of 128 questionnaires mailed to horse owners, 87 useable responses were received and 69 horses were subject to veterinary examination. Of the animals examined, 16% were underweight with body condition scores (BCS)<2/5, and 10% were overweight (BCS>3/5). This contrasted with the owner responses that reported 23% of the animals surveyed to be underweight and only 3% to be overweight. When assessed at trot, 77% of the horses were lame on at least one limb, with 97% having a reduced range of motion in at least one joint. Only 16% of these animals were reported by owners to have been lame within the previous 12 months. Owner-reported changes to hair coat were significantly associated with hirsutism or abnormal moulting detected at clinical examination (39%). At least one ophthalmic lesion was identified in all of the horses and ponies examined and 17% of owners reported that their animal had experienced visual problems within the previous year. Although dental abnormalities were detected in all animals where an oral examination was performed, only 42% of owners reported that their horse suffered from a known dental disorder. In general, despite a high prevalence of disease detected in these geriatric animals and with the majority having multiple abnormalities at clinical examination, there was under-reporting/under-recognition of these health problems by owners.