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Summary: Background: The recurrence rate of atrial fibrillation (AF) in horses after cardioversion to sinus rhythm (SR) is relatively high. Atrial fibrillatory rate (AFR) derived from surface ECG is considered a biomarker for electrical remodelling and could potentially be used for the prediction of successful AF cardioversion and AF recurrence. Objectives: Evaluate if AFR was associated with successful treatment and could predict AF recurrence in horses. Study design: Retrospective multicentre study. Methods: Electrocardiograms (ECG) from horses with persistent AF admitted for cardioversion with either medical treatment (quinidine) or transvenous electrical cardioversion (TVEC) were included. Bipolar surface ECG recordings were analysed by spatiotemporal cancellation of QRST complexes and calculation of AFR from the remaining atrial signal. Kaplan‐Meier survival curve and Cox regression analyses were performed to assess the relationship between AFR and the risk of AF recurrence. Results: Of the 195 horses included, 74 received quinidine treatment and 121 were treated with TVEC. Ten horses did not cardiovert to SR after quinidine treatment and AFR was higher in these, compared with the horses that successfully cardioverted to SR (median [interquartile range]), (383 [367‐422] vs 351 [332‐389] fibrillations per minute (fpm), P <.01). Within the first 180 days following AF cardioversion, 12% of the quinidine and 34% of TVEC horses had AF recurrence. For the horses successfully cardioverted with TVEC, AFR above 380 fpm was significantly associated with AF recurrence (hazard ratio = 2.4, 95% confidence interval 1.2‐4.8, P =.01). Main limitations: The treatment groups were different and not randomly allocated, therefore the two treatments cannot be compared. Medical records and the follow‐up strategy varied between the centres. Conclusions: High AFR is associated with failure of quinidine cardioversion and AF recurrence after successful TVEC. As a noninvasive marker that can be retrieved from surface ECG, AFR can be clinically useful in predicting the probability of responding to quinidine treatment as well as maintaining SR after electrical cardioversion. [ABSTRACT FROM AUTHOR]

Background: Focused cardiac ultrasound examination (FoCUS) is rapidly emerging for point‐of‐care cardiac assessment using hand‐carried ultrasound (HCU) devices. A specific FoCUS protocol for horses and adequate training guidelines currently are not available. Hypothesis: To gain knowledge about the training necessary to become proficient in performing FoCUS using a HCU device. Animals: Three healthy Warmblood horses were used for practical training of veterinarians and veterinary students in equine focused cardiac ultrasound (eFoCUS). Methods: Prospective educational study. An eFoCUS protocol and 1‐day training course were developed. Pre‐ and post‐course written tests were administered to participants to evaluate proficiency in knowledge of echocardiography and echocardiographic pathology. A post‐course practical examination involved performing eFoCUS and storage of representative images. Images were evaluated using an image quality score and compared between participants with some practical experience and participants with no practical experience. Results: Participants' knowledge of echocardiography increased significantly. Recognition of echocardiographic pathology pre‐course ranged from 40% to 90% (mean score, 65.7%) and post‐course from 85% to 100% (mean score, 92%). Eighteen of 21 participants were proficient in performing eFoCUS with a median image quality score of 79% (range, 42%‐95%). Image quality did not differ between participants with some practical experience compared to participants with no experience. Conclusions and Clinical Importance: Veterinarians and veterinary students independent of previous experience can become proficient in performing eFoCUS after completion of a 1‐day training course. [ABSTRACT FROM AUTHOR]

Background: Echocardiographic assessment of left ventricular (LV) size and function using area‐based indices and volumetric estimates is not well established in horses. Objective: To report reference intervals and measurement variability for uni‐, 2‐, and 3‐dimensional echocardiographic indices of LV size and systolic function in Warmblood horses and to provide proof of concept for allometric scaling of variables to body weight. Unidimensional indices were to be compared to area‐based indices and LV volume estimates to establish their clinical use. Animals Thirty healthy Warmblood horses and 70 Warmblood horses with a primary diagnosis of mitral regurgitation or aortic regurgitation. Methods: Echocardiographic indices of LV size and systolic function were measured using an existing echocardiography database. Weight‐related variables were scaled to body weight (BWT). Reference intervals and measurement variability were calculated, the influence of valvular regurgitation on LV size and function was investigated and agreement between different variables for detection of reduced, normal, and increased LV size and systolic function was assessed. Results: Reference values for healthy Warmblood horses were reported. Measurement variability was sufficiently low for clinical use of all variables. Allometric scaling was effective to correct diastolic LV dimensions and cardiac output for differences in BWT. Various echocardiographic indices resulted in different conclusions regarding identification of LV enlargement and systolic dysfunction in healthy horses and horses with valvular regurgitation. Conclusions and Clinical Importance: Echocardiographic assessment of LV size and systolic function should include joint assessment of multiple uni‐ and multidimensional indices. Area‐based or volumetric indices that reflect LV long‐axis motion should be included. [ABSTRACT FROM AUTHOR]

Background: Noninvasive blood pressures (NIBP) and pulse pressures (PP) have not been published in horses with aortic and mitral regurgitation (AR or MR). Objectives: To investigate NIBP and PP in healthy Warmblood horses and horses with AR and MR and propose PP cutoffs to identify and stage AR severity. Animals: Seventy‐three Warmblood horses (healthy, 10; AR, 31; MR, 32). Methods: Retrospective study. All horses had NIBP and an echocardiogram recorded. Cases were categorized based on severity of regurgitation. Pulse pressures were compared among healthy, MR, and AR groups and among AR severity groups. Cutoffs were determined by receiver operating characteristic curve analyses. Results: Horses with AR had higher PP than horses with MR (mean difference [95% confidence interval (CI)], +17 [9‐26] mm Hg, P < .001) and controls (+17 [5‐30] mm Hg; P =.004). Horses with severe AR had higher PP compared those with mild (+38 [20‐54] mm Hg; P < 0.001) and moderate AR (+33 [18‐47] mm Hg; P < .001). The PP cutoffs to distinguish AR from MR and controls were 38 mm Hg (sensitivity [Sn], 100%; specificity [Sp], 19%) for maximal Sn and 61 mm Hg (Sn, 43%; Sp, 100%) for maximal Sp. The PP cutoffs to distinguish severe AR from mild and moderate AR were 57 mm Hg (Sn, 100%; Sp, 70%) for maximal Sn and 77 mm Hg (Sn, 75%; Sp, 100%) for maximal Sp. Conclusions and Clinical Importance: Horses with AR have increased PP. Noninvasive PP measurements interpreted with provided cutoffs may aid clinicians in diagnosing and staging severity of AR in horses. [ABSTRACT FROM AUTHOR]

Objective To assess the accuracy and reliability of a point-of-care (POC) triglyceride analyzer and to establish reference intervals for blood ([TRIG]POC/WB) and plasma triglyceride concentrations ([TRIG]POC/PL) in horses, ponies, and donkeys. Design Prospective study. Setting University teaching hospital. Animals 120 adult healthy equids (78 horses and ponies, 42 donkeys) and 79 equids suffering from hypertriglyceridemia (73 horses and ponies, 6 donkeys). Interventions None. Measurements and Main Results [TRIG]POC/WB and [TRIG]POC/PL were measured using a POC analyzer and plasma triglyceride concentrations were measured using a standard laboratory assay ([TRIG]LAB/PL). Reference intervals were determined. Test accuracy was assessed by Bland-Altman comparison of POC measurements with standard laboratory measurements and by evaluating linearity of dilutional series. Test reliability was assessed by repeated serial measurements. [TRIG]POC/WB and [TRIG]POC/PL were below the analytic range of the POC assay (<0.8 mmol/L [<70 mg/dL]) in healthy horses and ponies, whereas the reference intervals were 0.82-3.14 mmol/L (73-278 mg/dL) and 0.87-3.02 mmol/L (77-267 mg/dL), respectively, in donkeys. The POC analyzer systematically overestimated triglyceride concentrations when compared to a standard laboratory assay. The difference between [TRIG]POC/WB and [TRIG]POC/PL was small and clinically negligible. The coefficient of variation of repeated measures performed on the POC analyzer was below 10% for [TRIG]POC/WB and [TRIG]POC/PL, both in horses and donkeys and at all concentration ranges. Conclusions The POC analyzer allows accurate and reliable measurement of [TRIG]POC/WB and [TRIG]POC/PL in horses, ponies, and donkeys in clinical settings. Assay-specific reference intervals should be determined for diagnosis and clinical monitoring of hypertriglyceridemia in equids. [ABSTRACT FROM AUTHOR]

Objectives To assess the measurement reliability of rotational thromboelastometry (ROTEM) measurements in horses, establish reference intervals for healthy horses, and evaluate the relationship between ROTEM variables, hematologic variables, and standard coagulation tests. Design Prospective observational study. Setting University teaching hospital. Animals Fifty healthy and 10 diseased adult horses. Interventions None. Measurements and Main Results Blood was sampled from 10 healthy and 10 diseased horses and samples were repeatedly analyzed to evaluate measurement reliability of various ROTEM variables. Four different ROTEM assays (ie, EXTEM, INTEM, FIBTEM, and APTEM) were run simultaneously under standardized conditions. The device-related, operator-related, and day-to-day variability for the majority of ROTEM variables was very low to low, as indicated by a coefficient of variation (CV) of < 15%. Most of test-retest variability of ROTEM variables appeared to be device-related. Blood samples from 50 clinically healthy horses were used to establish reference intervals for ROTEM variables. Multiple stepwise regression analyses identified associations of different ROTEM variables with hematocrit, total protein concentration, fibrinogen concentration, platelet count, prothrombin time, activated partial thromboplastin time, and thrombin time. Conclusions ROTEM is a feasible method to evaluate coagulation in horses. Its measurement reliability is acceptable, but device-related measurement variability has to be considered. Reference intervals are presented, but the influence of hematocrit, platelet count, and fibrinogen concentration may need to be taken into account when interpreting individual test results. [ABSTRACT FROM AUTHOR]

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Objective To evaluate the applicability and accuracy of a continuous glucose monitoring system (CGMS) in critically ill foals by comparing the performance of the CGMS, a point-of-care (POC) glucometer, and an in-house standard laboratory assay (SLA). Design Prospective study. Setting University teaching hospital. Animals Seven critically ill neonatal foals requiring intensive care. Interventions Foals were instrumented with a CGMS that measured interstitial glucose concentration every 5 minutes for the duration of 15-79 hours. Capillary and venous blood samples were taken every 4-6 hours for POC and SLA measurements, respectively. Measurements and Main Results Bland-Altman analysis showed a mean bias (95% limits of agreement) of -0.1 (-3.9 to 3.5) mmol/L for comparison of CGMS versus SLA, 0.06 (-3.9 to 4.0) mmol/L for comparison of CGMS versus POC glucometer, and -0.16 (-1.8 to 1.5) mmol/L for comparison of POC glucometer versus SLA. Percent agreement and weighted kappa for classification in hypoglycemia, normoglycemia, and hyperglycemia were 68.4% and 0.296 for CGMS versus SLA, 72.4% and 0.442 for CGMS versus POC glucometer, and 80.7% and 0.568 for POC glucometer versus SLA. Conclusions The CGMS may be helpful for monitoring a trend in interstitial glucose concentration in critically ill neonatal foals. However, considering the wide limits of agreement between methods, the CGMS should only be used as an adjunctive device to other, more accurate and readily available methods that are able to detect acute changes in glucose concentration. Its use is further limited by the relatively high costs of the sensors, the mandatory 2-hour initialization period, and the difficulties of keeping the transducer in place in an active foal. The POC glucometer used in this study is easy to use and proved to be sufficiently accurate for repeated, stall-sided glucose monitoring in neonatal foals. [ABSTRACT FROM AUTHOR]

A 6-year-old thoroughbred gelding was presented with a history of blepharospasm and opacity in the OS of 1 weeks’ duration. Ophthalmic examination findings were consistent with acute uveitis in the OS, and traditional treatment was initiated with systemic antibiotics and anti-inflammatory drugs, topical mydriatics, and corticosteroids. During the total treatment period of 4 weeks response to treatment was weak and the horse developed further problems such as cellulitis of the right hind limb with fever and eventually weight loss and dependent edema. Blood work was indicative of liver disease. Abdominal sonography revealed severe splenomegaly and slight hepatomegaly, and a liver biopsy confirmed malignant T-cell lymphoma. The horse was euthanized due to deteriorating general condition and subsequently underwent postmortem examination. Necropsy and histologic examination revealed a multicentric lymphoma with involvement of spleen, mesenteric lymph nodes, and OU. The findings in this case demonstrate that the differential diagnosis of intraocular and systemic lymphoma should be considered in any horse presenting with anterior uveitis, especially when uveitis is unresponsive to treatment and when additional systemic signs of illness such as lethargy, fever, weight loss, or dependent edema arise. Cytological examination of aqueous humor may provide a rapid diagnosis of intraocular lymphoma in eyes with clinical uveitis. [ABSTRACT FROM AUTHOR]