Assessment of cardiac troponin I (cTnI) and tissue velocity imaging (TVI) in 14 dogs with malignant lymphoma undergoing chemotherapy treatment with doxorubicin.

Doxorubicin has been shown to be cardiotoxic at high doses but is an efficacious chemotherapeutic agent in the treatment of canine lymphoma. Echocardiographic measurements and serum ultrasensitive cardiac troponin I (cTnI) levels were obtained before and after doxorubicin administration in 14 dogs diagnosed with lymphoma. The aim of this prospective study was to evaluate changes in cTnI concentrations and tissue velocity imaging (TVI) values in dogs with lymphoma undergoing chemotherapy with doxorubicin. A total of 182 cTnI and 1017 TVI measurements were performed. Standard echocardiographic parameters, tissue Doppler indices and cTnI concentrations did not differ at any time point within a 12-week cyclic combination protocol. In conclusion, the use of doxorubicin at standard doses in the treatment of canine lymphoma may not be associated with significant myocardial damage.

Predictors of Sudden Cardiac Death in Doberman Pinschers with Dilated Cardiomyopathy.

BACKGROUND: Doberman Pinschers with dilated cardiomyopathy (DCM) are at high risk of sudden cardiac death (SCD). Risk factors for SCD are poorly defined. AIM: To assess cardiac biomarkers, Holter-ECG, echocardiographic variables and canine characteristics in a group of Doberman Pinschers with DCM dying of SCD and in a DCM control group to identify factors predicting SCD. METHODS/ANIMALS: A longitudinal prospective study was performed in 95 Doberman Pinschers with DCM. Forty-one dogs died within 3 months after the last cardiac examination (SCD-group) and were compared to 54 Doberman Pinschers with DCM surviving 1 year after inclusion. Holter-ECG, echocardiography, measurement of N-terminal prohormone of brain-natriuretic peptide (NT-proBNP), and cardiac Troponin I (cTnI) concentrations were recorded for all dogs. RESULTS: Volume overload of the left ventricle (left ventricular end-diastolic volume (LVEDV/BSA) > 91.3 mL/m²) was the single best variable to predict SCD. The probability of SCD increases 8.5-fold (CI0.95  = 0.8-35.3) for every 50 mL/m²-unit increment in LVEDV/BSA. Ejection fraction (EF), left ventricular end-systolic volume (LVESV/BSA) and NT-proBNP were highly correlated with LVEDV/BSA (r = -0.63, 0.96, 0.86, respectively). Generated conditional inference trees (CTREEs) revealed that the presence of ventricular tachycardia (VT), increased concentration of cTnI, and the fastest rate (FR) of ventricular premature complexes (VPC) ≥260 beats per minute (bpm) are additional important variables to predict SCD. CONCLUSION: Conditional inference trees provided in this study might be useful for risk assessment of SCD in Doberman Pinschers with DCM.

The role of hypothyroidism in the etiology and progression of dilated cardiomyopathy in Doberman Pinschers.

BACKGROUND: Hypothyroidism and dilated cardiomyopathy (DCM) are both common diseases in Doberman Pinschers. A possible influence of hypothyroidism on the etiology and progression of DCM is controversial. OBJECTIVES: Evaluation of the role of hypothyroidism in etiology and progression of DCM. ANIMALS: A total of 175 Doberman Pinschers. METHODS: In this longitudinal prospective study, echocardiography and 24-hour ambulatory ECG recordings were performed in all dogs as screening tests for DCM. Total thyroxine (TT4 ) and thyroid ultrasonography served as initial screening tests for hypothyroidism and low TT4 values were followed up by a thyroid stimulating hormone (TSH) test or free total thyroxine (fT4 )/cTSH measurements. Additionally, a follow-up study of dogs affected by both DCM and hypothyroidism under optimal treatment for hypothyroidism was conducted. RESULTS: A total of 107 dogs were healthy, 45 dogs had DCM, 11 hypothyroidism, and 12 dogs had both DCM and hypothyroidism. TT4 values as well as the thyroid volumes were equivalent in the healthy dogs and in those with DCM. Neither ventricular premature complexes nor echocardiographic parameters differed between healthy and hypothyroid dogs. Dogs with DCM had a 2.26-fold (CI0.95 = 1.1-4.8) higher risk of also being affected by hypothyroidism. Despite optimal thyroid treatment of dogs with hypothyroidism and DCM, there was a progression of the heart disease. CONCLUSIONS AND CLINICAL IMPORTANCE: This study did not confirm a role of hypothyroidism in the etiology or progression of DCM. Treatment of hypothyroidism did not improve the clinical outcome.

Ventricular fractional shortening in 108 dogs with malignant lymphoma undergoing chemotherapy with a cyclic combination protocol including doxorubicin.

OBJECTIVE: The aim of this study was to evaluate whether changes in the left ventricular fractional shortening (LVFS) can be detected in dogs with malignant lymphoma undergoing a cyclic combination chemotherapy protocol including doxorubicin. HYPOTHESIS: Left ventricular fractional shortening as a stand-alone measurement will not show a significant change during the cyclic combination protocol. MATERIAL AND METHODS: In this retrospective study, the records of dogs with malignant lymphoma treated between April 2001 and October 2010 were reviewed. Inclusion criteria comprised: a diagnosis of malignant lymphoma, a cyclic combination chemotherapy (including L-asparaginase, vincristine, cyclophosphamide, doxorubicin and prednisolone), and an echocardiographic examination by an experienced examiner before treatment and after each doxorubicin administration. RESULTS: One hundred and eight dogs were included and a total of 446 LVFS measurements had been performed. Patients were divided into four groups according to the number of doxorubicin administrations. Median LVFS did not change significantly during the cyclic combination protocol in all groups. All median LVFS values remained above the lower reference value of 25%. CONCLUSION AND CLINICAL RELEVANCE: The measurement of LVFS did not show a significant change during the cyclic combination protocol treatment including doxorubicin in this population of dogs. Therefore either this cyclic combination protocol does not cause a systolic dysfunction or LVFS is not sensitive enough to detect early changes. Newer methods that are more sensitive then LVFS might be necessary to detect such changes.