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OBJECTIVE: Borzoi reportedly experience sudden death. The objective of this study was to report ECG intervals, amplitudes, and frequency of ECG abnormalities in clinically healthy Borzoi. METHODS: 98 clinically healthy Borzoi were prospectively recruited and underwent echocardiogram, ECG, and cardiac troponin I testing between October 2020 and December 2022. Standard ECG measurements were obtained. Early repolarization notches and slurs were recorded. RESULTS: Of 82 Borzoi with a structurally normal echocardiogram, ventricular arrhythmias were documented in 8 (10%) dogs, all of which had normal cardiac troponin I concentrations. Median P wave duration was 55 milliseconds (range, 45 to 70 milliseconds). Median PR interval was 125 milliseconds (range, 80 to 175 milliseconds). Thirty-one (38%) Borzoi had first-degree atrioventricular block (PR interval > 130 milliseconds). Median QRS duration was 65 milliseconds (range, 48 to 90 milliseconds). Median QT interval was 235 milliseconds (range, 185 to 275 milliseconds). Twenty-nine (35%) and 15 (18%) of 82 Borzoi had QT intervals > 240 or > 250 milliseconds, respectively. Sixty-seven of 82 (82%) Borzoi had early repolarization notches or slurs. Seventeen of 82 (21%) Borzoi had an abnormality of the ST segment, most commonly convexity/doming. Convexity of the ST segment was intermittent (n = 9) or persistent (4). CONCLUSIONS: Ventricular arrhythmias, early repolarization, prolonged QT intervals, and ST segment abnormalities are not infrequent in clinically healthy Borzoi. P, PR, and QRS durations are commonly prolonged compared to general canine reference intervals. CLINICAL RELEVANCE: Future study into heritable channelopathies in Borzoi is warranted given the frequency of ventricular arrhythmias, repolarization abnormalities, and sudden death in the breed. Breed-specific ECG reference intervals are needed.
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BACKGROUND: The magnitude of diagnostic abnormalities can influence the perception of clinical outcome. Extreme neutrophilic leukocytosis (ENL) is an uncommon finding caused by markedly increased granulopoiesis. A lack of recent, large-scale studies limits our understanding of the importance, causation, and prognosis associated with ENL in dogs. HYPOTHESIS/OBJECTIVES: Describe disease categories (DC) identified in dogs with ENL and identify variables associated with survival. We hypothesized that factors including fever, segmented and band neutrophil counts, and DC would be negatively associated with survival. ANIMALS: Two-hundred sixty-nine dogs with ENL (segmented neutrophils ≥50 × 103 cells/µL) presented to the veterinary teaching hospitals at Auburn University (n = 164), the University of Missouri (n = 81), and Oklahoma State University (n = 24) between January 1, 2009 and December 31, 2019. METHODS: Retrospective study. Demographic data and outcome variables including temperature, CBC findings, DC, duration of hospitalization (DOH) and outcome were acquired from the medical record. Statistical analyses included chi-squared and Kruskal-Wallis tests, and Pearson product moment correlations with a P < .05 significance level. RESULTS: Mortality was 41%. Survival differed with DC (P = .002). Mortality was higher (P < .05) in dogs with neoplasia (56.2%) vs immune-mediated disease (20.5%) or tissue damage/necrosis (19%). Weight (P = .001, r = -0.14) and total neutrophil count (P = .04, r = -0.02) were weakly negatively associated with survival whereas DOH was weakly positively associated with survival (P = .03, r = 0.14). CONCLUSIONS AND CLINICAL IMPORTANCE: Mortality in dogs with ENL is high but differed according to DC. Only weak correlations between clinical or clinicopathologic variables and mortality were identified. Extreme neutrophilic leukocytosis should be interpreted in conjunction with the underlying disease process, and not broadly used to predict clinical outcome.