Cardiac Troponin I Concentrations in Ponies Challenged with Equine Influenza Virus

Abstract

Background: Myocarditis is thought to occur secondary to equine influenza virus (EIV) infections in horses, but there is a lack of published evidence. Hypothesis/Objectives: We proposed that EIV challenge infection in ponies would cause myocardial damage, detectable by increases in plasma cardiac troponin I (cTnI) concentrations. Animals: Twenty‐nine influenza‐naïve yearling ponies: 23 were part of an influenza vaccine study (11 unvaccinated and 12 vaccinated), and were challenged with 108 EID50 EIV A/eq/Kentucky/91 6 months after vaccination. Six age‐matched healthy and unvaccinated ponies concurrently housed in a separate facility not exposed to influenza served as controls. Methods: Heparinized blood was collected before and over 28 days after infection and cTnI determined. Repeated measures analysis of variance, chi‐square, or clustered regression analyses were used to identify relationships between each group and cTnI. Results: All EIV‐infected ponies developed clinical signs and viral shedding, with the unvaccinated group displaying severe signs. One vaccinated pony and 2 unvaccinated ponies had cTnI greater than the reference range at 1 time point. At all other times, cTnI was <0.05 ng/mL. All control ponies had normal cTnI. There were no significant associations between cTnI and either clinical signs or experimental groups. When separated into abnormal versus normal cTnI, there were no significant differences among groups. Conclusions and Clinical Importance: This study demonstrated no evidence of severe myocardial necrosis secondary to EIV challenge with 108 EID50 EIV A/eq/Kentucky/91 in these sedentary ponies, but transient increases in cTnI suggest that mild myocardial damage may occur.

Cardiotoxicity, Inflammation, and Immune Response after Rattlesnake Envenomation in the Horse

“…A number of studies have utilized cTnI as a sensitive marker to document myocardial injury in the horse, and its use is becoming more common in the clinical evaluation of horses bitten by rattlesnakes. The cTnI from the rattlesnake‐bitten horses was compared with the established normal range for the laboratory performing the assay.…”

Resolution of sustained narrow complex ventricular tachycardia and tachycardia-induced cardiomyopathy in a Quarter Horse following quinidine therapy

“…These findings may provide an explanation for the lack of cTnI elevation and significant, lasting, cardiac changes seen in this case, as possible EIV infection was months prior to evaluation. 22 Tachyarrhythmias of this duration and severity are sufficient to induce congestive heart failure in artificially paced dogs, yet this patient remained stable with only a change in demeanor and activity level. Tolerance of this rhythm may have been related to an origin in the junction or high in the intraventricular septum, thus mimicking a more normal pattern of conduction, in contrast to ectopy arising from lower portions of the ventricle.…”

“…25,26 In a recent study evaluating the cardiac effects of EIV infection in ponies, transient increases in cTnI were measured at 28 days postinfection but no evidence of severe myocardial necrosis was found. 22 In this study, cTnI levels beyond 28 days post-infection were not measured. These findings may provide an explanation for the lack of cTnI elevation and significant, lasting, cardiac changes seen in this case, as possible EIV infection was months prior to evaluation.…”

Biomarkers for differentiation of causes of respiratory distress in dogs and cats: Part 1 – Cardiac diseases and pulmonary hypertension

“…Similar to people, these processes include both cardiac-specific disease processes and those which are more pulmonary or systemic in nature. [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] In small animal veterinary medicine, the use of cTn has been evaluated in a number of pathologic conditions as an aid for diagnosis and has shown applicability in numerous conditions (see Table 1). Although each analyzer has its own reported reference interval, typically these values are very low (<0.2 ng/mL).…”

“…cTn has been evaluated in several disease processes in large animals including horses and cows. Similar to people, these processes include both cardiac‐specific disease processes and those which are more pulmonary or systemic in nature …”