Serum cardiac troponin I concentrations in clinically normal and Dirofilaria immitis infected Korean Jindo dogs

Abstract

Abstract : This study was conducted to determine the serum cardiac troponin I (cTnI) concentrations in clinically normal(uninfected) Korean Jindo dogs and those infected with Dirofilaria (D.) immitis. Forty Korean Jindo dogs (22 females,18 males) were obtained from two kennels in the Boryeong area of Chungnam Province and the Daejeon area, Korea.Significantly higher cTnI concentrations were observed in D. immitis-infected dogs than clinically normal dogs. cTnItesting in addition to thoracic radiography, echocardiography, and electrocardiography shows promise as an additionalmethod for diagnosis of heartworm infection.Keywords : cardiac troponin I, Dirofilaria immitis, Korean Jindo dog Dirofilaria (D.) immitis resides in the pulmonary arteries,right ventricle, and right atrium of infected dogs, cats, ferretsand wild canids in temperate, tropic and subtropic zones [4].Canine heartworm disease can be manifested by thromboem-bolism, pulmonary hypertension, right-sided congestive heartfailure, and ascites. Korea is in the temperate zone and is oneof the enzootic regions of D. immitis [7, 8]. The prevalenceof heartworm disease in Korean dogs was estimated to be28.3% in a survey conducted from 1994 to 1995 that used anantigen test [3]. Using a similar antigen test, a recent surveyof several Korean provinces, conducted from 2001 to 2002,revealed an increase in the prevalence of heartworm infec-tion to 40.0% [7]. However, a recent report showed thatnumbers of cases of canine heartworm disease diagnosedfrom 2007 to 2008 had decreased, although the risk of expo-sure to this nematode in the breeding farms is still high [8].Injury to the sarcomere leads to the detachment of cardiactroponin I (cTnI) from actin, and the subsequent disruption ofthe cell membrane allows leakage of cTnI into the generalcirculation [5]. A high level of cTnI in serum or plasma isconsidered to be a very sensitive and specific indicator ofmyocardial cell damage and necrosis [5]. An elevated cTnIconcentration is associated with poor long-term outcomesand is an independent predictor of mortality [2]. The objec-tive of this study was to determine serum cTnI concentrationin Korean Jindo dogs clinically normal and uninfected orinfected with D. immitis. Forty Korean Jindo dogs (22 females, 18 males; weight,17~23 kg) were obtained from 2 kennels in the Boryeongarea of Chungnam Province and the Daejeon area, Korea.The ages of the dogs ranged from 1 to 12 years (median; 4.1years). They underwent physical examinations, and evalua-tions of serum biochemistries and cTnI concentrations. Thedogs were divided into 2 groups. Twenty dogs were assignedto the clinically normal group and 20 dogs were assigned tothe D. immitis-infected group. None of the D. immitis-infected dogs had laboratory abnormalities or clinical signssuch as exercise intolerance, dyspnea, cough, ascites and car-diac murmurs. To these dogs were therefore classified withmild canine heartworm disease severity [5]. The dogs werefasted for 12 hours prior to blood collection. Blood sampleswere collected through cephalic venipuncture, and each sam-ple was allowed to clot at room temperature for 30 min, andthen centrifuged at 1,500 × g for 5 min. Aliquots of serumwere frozen in plastic tubes at −80