Cardiac troponin I in canine patients with lymphoma and osteosarcoma receiving doxorubicin: comparison with clinical heart disease in a retrospective analysis

Cardioprotective effect of allyl isothiocyanate in a rat model of doxorubicin acute toxicity

Doxorubicin (DOX) is an effective anthracycline chemotherapeutic drug. Nevertheless, the cardiotoxicity adverse effect restricts its clinical benefit. Allyl isothiocyanate (AITC) is a natural antioxidant and anti-inflammatory agent. In the present study, we investigated the effect of AITC on cardiotoxicity of DOX. Thirty-two adult male albino rats were divided into four groups; control, AITC, DOX, and AITC + DOX. AITC was administrated orally (25 mg/kg/day) for 7 days, and DOX was given as a single i.p. injection (15 mg/kg) on the third day. Mortality rate was observed during the experiment. Cardiac toxicity markers (lactate dehydrogenase (LDH), creatine kinase (CK-MB), and cardiac Troponin I (cTn-I)) were evaluated in serum samples obtained from all groups after 48 hours of DOX injection. DOX-treated group showed 40% mortality and a significant increase in cardiac enzymes. This increase was accompanied by degenerated cardiomyocytes, and inflammatory cells infiltrates. Interestingly, AITC administration alleviated myocardial oxidative stress induced by DOX as attenuated the increase in malondialdehyde (MDA), and nitric oxide (NO) while resulted in elevations of the antioxidant reduced glutathione (GSH) level as well as superoxide dismutase (SOD) activity. Furthermore, the inflammatory cytokine, TNF-α, was reduced upon administration of AITC with DOX. The cardio-protection of AITC is attributed to increase the expression of cytoprotective nuclear factor erythroid 2-related factor 2 (Nrf2). Subsequently, heme oxygenase 1 (HO-1) level was elevated by AITC to correct the oxidative stress induced by DOX in the heart. Accordingly, AITC ameliorated acute cardiotoxicity associated with DOX treatment via attenuation of oxidative stress and the induced-tissue inflammatory injury. Abbreviations: DOX: doxrubicin; Nrf2: nuclear factor erythroid 2-related factor 2; HO-1: heme oxygenase 1; AITC: ally isothiocyanate; MDA: malondialdehyde; SOD: superoxide dismutase; GSH: reduced glutathione; TNF-α: tumor necrosis factor alpha.

Evaluation of cardioprotective effects of carvedilol in dogs receiving doxorubicin chemotherapy: A prospective, randomized, double-blind, placebo controlled pilot study

The aim of this pilot study was to evaluate the cardioprotective effects of carvedilol in dogs receiving doxorubicin chemotherapy and provide suggestions to future studies based on results and limitations of our study. Thirteen dogs were randomized into two experimental groups: 6 dogs in carvedilol group and 7 dogs in placebo group. In carvedilol group, 0.39 mg/kg ± 0.04 twice-daily oral carvedilol was started on the day of the first doxorubicin treatment and continued throughout the chemotherapy protocol until the final cardiological evaluation. Cardiological evaluations were performed before the first doxorubicin administration and then 10 to 15 days after each subsequent dose. Troponin I and oxidative stress tests were performed with serum collected from dogs at the initial and final cardiological evaluation. Carvedilol produced some echocardiographic and electrocardiographic changes (reduced E velocity and E/IVRT ratio, as well reduced heart rate and increased PR and QT interval) due to its beta-block effect. In placebo group Doppler study showed a significant increase in mitral flow deceleration time (EDT), as well increased amplitude of the S wave in the right, and R wave in the left, precordial chest leads. There were significant difference in the EDT, E/IVRT and A' velocity, as well heart rate, PR interval and R wave in V4/CV6LU precordial chest lead between groups. In conclusion, some indexes of diastolic function and in precordial chest leads were less affected by doxorubicin in carvedilol than in control group. This suggests that carvedilol may have a beneficial effect in canine cancer patients receiving doxorubicin.

Extracellular vesicular microRNAs as potential biomarker for early detection of doxorubicin-induced cardiotoxicity

Background

Long‐term use of doxorubicin (DOX) is limited by cumulative dose‐dependent cardiotoxicity.

Objectives

Identify plasma extracellular vesicle (EV)‐associated microRNAs (miRNAs) as a biomarker for cardiotoxicity in dogs by correlating changes with cardiac troponin I (cTnI) concentrations and, echocardiographic and histologic findings.

Animals

Prospective study of 9 client‐owned dogs diagnosed with sarcoma and receiving DOX single‐agent chemotherapy (total of 5 DOX treatments). Dogs with clinically relevant metastatic disease, preexisting heart disease, or breeds predisposed to cardiomyopathy were excluded.

Methods

Serum concentration of cTnI was monitored before each treatment and 1 month after the treatment completion. Echocardiography was performed before treatments 1, 3, 5, and 1 month after completion. The EV‐miRNA was isolated and sequenced before treatments 1 and 3, and 1 month after completion.

Results

Linear mixed model analysis for repeated measurements was used to evaluate the effect of DOX. The miR‐107 (P = .03) and miR‐146a (P = .02) were significantly downregulated whereas miR‐502 (P = .02) was upregulated. Changes in miR‐502 were significant before administration of the third chemotherapeutic dose. When stratifying miRNA expression for change in left ventricular ejection fraction, upregulation of miR‐181d was noted (P = .01). Serum concentration of cTnI changed significantly but only 1 month after treatment completion, and concentrations correlated with left ventricular ejection fraction and left ventricular internal dimension in diastole.

Conclusion and Clinical Significance

Downregulation of miR‐502 was detected before significant changes in cTnI concentrations or echocardiographic parameters. Further validation using a larger sample size will be required.

Incidence and risk factors associated with development of clinical cardiotoxicity in dogs receiving doxorubicin

Background

Doxorubicin (DOX) can cause cumulative cardiotoxicity in dogs, but the incidence of clinical cardiotoxicity in dogs receiving DOX has not been determined.

Hypothesis/Objectives

To determine if the duration of DOX infusion influences the incidence of cardiotoxicity, to characterize the incidence of clinical cardiotoxicity in dogs during or after DOX chemotherapy, and to identify any risk factors associated with cardiotoxicity.

Animals

Four‐hundred ninety‐four dogs that received at least 1 dose of DOX for the treatment of cancer.

Methods

Retrospective study of dogs that received DOX from 2006 to 2015.

Results

Of 494 dogs, 20 (4.0%) developed clinical cardiotoxicity. The duration of DOX infusion was not significantly associated with clinical cardiotoxicity, whereas a higher cumulative dose of DOX, higher body weight, decreases in fractional shortening after 5 doses of DOX, and development of ventricular premature contractions were significantly associated with clinical cardiotoxicity. High‐risk breeds for developing dilated cardiomyopathy had an incidence of 15.4%, whereas low‐risk breeds had an incidence of 3.0%.

Conclusions and Clinical Importance

Although the duration of DOX infusion did not influence the incidence of cardiotoxicity, premature contractions and decreases in fractional shortening should raise concern for the development of clinical cardiotoxicity. Overall, the incidence of clinical DOX‐induced cardiotoxicity is low, but Boxers and other breeds at high risk for dilated cardiomyopathy may be at an increased risk.

How the Future of Sonography May Change the Outlook for Patients With Osteosarcoma

Sonography currently provides a variety of tools to support the diagnosis and treatment of osteosarcoma and, with the development of therapeutic ultrasound practices, could play an increasingly important role in the treatment of future patients with osteosarcoma. Currently, computed tomography, magnetic resonance imaging, and radiography are the preferred imaging modalities for bone lesions; treatment options for osteosarcoma primarily include highly toxic chemotherapies and surgeries that often result in limb loss. Unfortunately, osteosarcoma is rarely eliminated, and despite this, patients lose their lives after having a significant reduction in quality of life. Evolving therapies such as high-frequency focused ultrasound, ultrasound-enhanced delivery of photodynamic therapy, and low-intensity pulsed ultrasound may offer these patients an improved quality of life while also increasing efficacy of treatment. This canine case study illustrates the various ways in which sonography might contribute to the treatment plan for patients with osteosarcoma. It may provide a comparable model for the reimagining of treatment for future patients with osteosarcoma using a suite of therapeutic ultrasound applications.

Prospective evaluation of Doppler echocardiography, tissue Doppler imaging and biomarkers measurement for the detection of doxorubicin-induced cardiotoxicity in dogs: A pilot study

The purpose of this pilot study was to evaluate the usefulness of selected echocardiographic parameters, NT-proBNP and cardiac troponin I (cTnI) in the detection of cardiotoxicity in dogs treated with doxorubicin for various malignancies. Echocardiographic studies and biomarker measurements were performed before each administration of doxorubicin, then 1 and 3 months after completion of therapy. Thirteen dogs were included, with a total cumulative dose of doxorubicin ranging from 30 to 150 mg/m(2). E/A ratio significantly decreased during doxorubicin administration (p=0.047). cTnI level was also significantly affected by treatment (p=0.046), increasing above normal at least at one time point in 11 of 13 dogs. The results of this pilot study suggest that monitoring of left ventricular diastolic function and cTnI level measurement might be useful in the early detection of cardiotoxic signs of doxorubicin therapy in dogs.

Cardiac Troponins in Dogs and Cats

Cardiac troponins are sensitive and specific markers of myocardial injury. The troponin concentration can be thought of as a quantitative measure of the degree of injury sustained by the heart, however, it provides no information on the cause of injury or the mechanism of troponin release. Conventionally, the cardiac troponins have been used for diagnosis of acute myocardial infarction in humans and have become the gold standard biomarkers for this indication. They have become increasingly recognized as an objective measure of cardiomyocyte status in both cardiac and noncardiac disease, supplying additional information to that provided by echocardiography and ECG. Injury to cardiomyocytes can occur through a variety of mechanisms with subsequent release of troponins. Independent of the underlying disease or the mechanism of troponin release, the presence of myocardial injury is associated with an increased risk of death. As increasingly sensitive assays are introduced, the frequent occurrence of myocardial injury is becoming apparent, and our understanding of its causes and importance is constantly evolving. Presently troponins are valuable for detecting a subgroup of patients with higher risk of death. Future research is needed to clarify whether troponins can serve as monitoring tools guiding treatment, whether administering more aggressive treatment to patients with evidence of myocardial injury is beneficial, and whether normalizing of troponin concentrations in patients presenting with evidence of myocardial injury is associated with reduced risk of death.

Characterization of the Canine Anthracycline-Metabolizing Enzyme Carbonyl Reductase 1 (cbr1) and the Functional Isoform cbr1 V218

The anthracyclines doxorubicin and daunorubicin are used in the treatment of various human and canine cancers, but anthracycline-related cardiotoxicity limits their clinical utility. The formation of anthracycline C-13 alcohol metabolites (e.g., doxorubicinol and daunorubicinol) contributes to the development of anthracycline-related cardiotoxicity. The enzymes responsible for the synthesis of anthracycline C-13 alcohol metabolites in canines remain to be elucidated. We hypothesized that canine carbonyl reductase 1 (cbr1), the homolog of the prominent anthracycline reductase human CBR1, would have anthracycline reductase activity. Recombinant canine cbr1 (molecular weight: 32.8 kDa) was purified from Escherichia coli. The enzyme kinetics of "wild-type" canine cbr1 (cbr1 D218) and a variant isoform (cbr1 V218) were characterized with the substrates daunorubicin and menadione, as well as the flavonoid inhibitor rutin. Canine cbr1 catalyzes the reduction of daunorubicin to daunorubicinol, with cbr1 D218 and cbr1 V218 displaying different kinetic parameters (cbr1 D218 Km: 188 ± 144 μM versus cbr1 V218 Km: 527 ± 136 μM, P < 0.05, and cbr1 D218 Vmax: 6446 ± 3615 nmol/min per milligram versus cbr1 V218 Vmax: 15539 ± 2623 nmol/min per milligram, P < 0.01). Canine cbr1 also metabolized menadione (cbr1 D218 Km: 104 ± 50 μM, Vmax: 2034 ± 307 nmol/min per milligram). Rutin acted as a competitive inhibitor for the reduction of daunorubicin (cbr1 D218 Ki: 1.84 ± 1.02 μM, cbr1 V218 Ki: 1.38 ± 0.47 μM). These studies show that canine cbr1 metabolizes daunorubicin and provide the necessary foundation to characterize the role of cbr1 in the variable pharmacodynamics of anthracyclines in canine cancer patients.

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.

Elimination half-life of intravenously administered equine cardiac troponin I in healthy ponies

REASONS FOR PERFORMING STUDY

To date, no information is available on the true biological elimination half-life (T(1/2) ) of cardiac troponin I (cTnI) in the equine species. Such data are required to better evaluate the optimal time to acquire the cTnI sample following acute myocardial injury.

OBJECTIVE

To determine the T(1/2) of equine cTnI.

METHODS

Four healthy ponies received i.v. injections of recombinant equine cTnI. Plasma cTnI concentrations were measured with a point-of-care cTnI analyser at multiple time points after injection. Standard pharmacokinetic analysis was performed to establish the T(1/2) of cTnI.

RESULTS

The average T(1/2) of cTnI was determined to be 0.47 h using a single rate elimination model.

CONCLUSION

The elimination of recombinant equine cTnI following i.v. administration is very rapid. Establishing the T(1/2 ) of troponin provides critical information in understanding the clinical application of this cardiac biomarker in equine practice.

Value of echocardiography and electrocardiography as screening tools prior to Doxorubicin administration

The dose-limiting toxicity of doxorubicin is cardiotoxicosis. The authors of this report hypothesized that by using their institution's adopted guidelines (that involve prescreening echocardiography and electrocardiography), they would detect pre-existing cardiac abnormalities that preclude doxorubicin administration in <10% of dogs. Of 101 dogs, only 6 were excluded from doxorubicin administration based on electrocardiogram abnormalities, with a majority of those arrhythmias classified as ventricular premature contractions. One patient was excluded based on echocardiogram alone due to hypertrophic cardiomyopathy. The incidence of cardiotoxicity in treated dogs was 8% (8/101). Additional pretreatment and ongoing studies are indicated to identify risk factors for cardiotoxicity.

Measurement of cardiac troponin I utilizing a point of care analyzer in healthy alpacas

BACKGROUND

Myocardial disease in camelids is poorly characterized. Nutritional (selenium deficiency) and toxic (ionophore toxicity) myocardial disease have been reported in camelids. Diagnosis and management of these and other myocardial diseases might be enhanced by evaluating cardiac troponin I (cTnI) concentrations. No information about cTnI reference intervals in camelids is currently available.

HYPOTHESIS/OBJECTIVES

(A) To determine cTnI concentrations obtained using a point of care i-STAT(®)1 analyzer (Heska Corporation) in healthy alpacas; (B) to compare alpaca cTnI concentrations between heparinized whole blood and plasma samples and between 2 different storage conditions (4 °C for 24 h or -80 °C for 30 days); (C) to examine assay reproducibility using the i-STAT(®)1.

ANIMALS, MATERIALS AND METHODS

23 healthy alpacas were evaluated. Blood and plasma samples were analyzed by the i-STAT(®)1 within 1 h of collection. Aliquots of plasma were stored at either 4 °C for 24 h or -80 °C for 30 days, and then analyzed. Assay reproducibility was determined by comparing 2 plasma or whole blood cTnI concentrations measured on the same sample over a 10 min period.

RESULTS

Analyzer-specific plasma cTnI concentrations in clinically normal alpacas had a median of <0.02 ng/mL (range: <0.02 ng/mL to 0.07 ng/mL). Plasma and whole blood concentrations showed good agreement. Storage did not affect cTnI concentrations (p > 0.75). Plasma cTnI concentrations had coefficient of repeatability of 0.02 ng/mL.

CONCLUSIONS

The i-STAT(®)1 can measure cTnI in alpacas on both plasma and whole blood and provides similar values for both samples. Storage at 4 °C for 24 h or -80 °C for 30 days does not affect estimates of plasma cTnI. Evaluation of cTnI might be of value in assessing cardiac disease in this species.

Toxicity associated with epirubicin treatments in a large case series of dogs

Epirubicin is a stereoisomer of doxorubicin that is widely used in human oncology. The purpose of this study was to evaluate the toxicity associated with epirubicin administration in dogs. Three hundred and fifteen treatments were administered to 139 dogs. Patients received between one and seven doses. One hundred and sixteen treatments were associated with toxicity in 81 patients (50 episodes of lethargy, 49 of diarrhoea, 42 of vomiting, 40 of anorexia, 2 hypersensitivity reactions and 2 suspected extravasations). Thirty-six (11%) adverse events resulted in hospitalization in 33 (24%) patients, of which 15 were neutropenic and 9 pyrexic. Mean duration of hospitalization was 3.4 days and 33 patients recovered uneventfully. Owners of 11 patients declined further treatment after toxicity occurred. After 25 treatments associated with toxicity, dose reductions reduced toxicity. The use of prophylactic anti-emetics, gastroprotectants and antibiotics did not reduce the frequency of gastrointestinal toxicity.

Safety of concurrent administration of dexrazoxane and doxorubicin in the canine cancer patient

Doxorubicin may cause a rare but serious cardiotoxicity. Dexrazoxane is a cardioprotectant drug used to reduce the risk of cardiotoxicity in human patients. In this study, 25 tumour-bearing dogs were treated with concurrent doxorubicin and dexrazoxane. The total number of doses of dexrazoxane given was 54 (range 1-5 doses per dog, median 2 doses). Five dogs received more than 165 mg m(2) cumulative doxorubicin dose before starting dexrazoxane. Haematologic, gastrointestinal and cardiovascular toxicities were considered tolerable. The combination of doxorubicin with dexrazoxane was well tolerated with minimal side-effects in this patient cohort. Future studies are required to evaluate potential cardioprotective effects of dexrazoxane given concurrently with doxorubicin.

Comparison of plasma cardiac troponin I concentrations among dogs with cardiac hemangiosarcoma, noncardiac hemangiosarcoma, other neoplasms, and pericardial effusion of nonhemangiosarcoma origin

OBJECTIVE

To determine whether plasma cardiac troponin I (cTnl) concentrations can be used to identify cardiac involvement in dogs with hemangiosarcoma, exclude cardiac hemangiosarcoma in dogs with noncardiac hemangiosarcoma, and identify cardiac hemangiosarcoma in dogs with pericardial effusion.

DESIGN

Cohort study.

ANIMALS

57 dogs (18 with confirmed [5 dogs] or suspected [13] cardiac hemangiosarcoma, 14 with confirmed hemangiosarcoma involving sites other than the heart [noncardiac hemangiosarcoma], 10 with pericardial effusion not caused by hemangiosarcoma, and 15 with noncardiac nonhemangiosarcoma neoplasms).

PROCEDURES

Plasma cTnl concentration was measured, and thoracic radiography, abdominal ultrasonography, and echocardiography were performed in each dog. The cTnl concentration was compared among groups.

RESULTS

Median plasma cTnl concentration in dogs with cardiac hemangiosarcoma was significantly higher than the concentration in each of the other groups. A plasma cTnl concentration > 0.25 ng/mL could be used to identify cardiac involvement in dogs with hemangiosarcoma at any site (sensitivity, 78%; specificity, 71 %). A plasma cTnl concentration > 0.25 ng/mL could be used to identify cardiac hemangiosarcoma in dogs with pericardia effusion (sensitivity, 81%; specificity, 100%).

CONCLUSIONS AND CLINICAL RELEVANCE

The median plasma cTnl concentration was higher in dogs with cardiac hemangiosarcoma, compared with the median concentration in dogs with hemangiosarcoma at other sites, dogs with other neoplasms, and dogs with pericardial effusion not caused by hemangiosarcoma. The plasma cTnl concentration may be used to identify cardiac involvement in dogs with hemangiosarcoma and to identify cardiac hemangiosarcoma in dogs with pericardial effusion.

Prognostic and predictive biomarkers of canine osteosarcoma

Canine osteosarcoma (OS) is an aggressive tumour that accounts for approximately 90% of primary bone tumours in the dog. Although the standard treatments (including limb amputation/sparing, chemotherapy and palliative radiotherapy) have significantly increased survival rates, almost 90% of animals will eventually develop predominantly pulmonary metastases. Despite advances in various therapies, prognosis remains poor, with median survival times ranging from 3 months to 1 year and <20% of dogs survive for >2 years following diagnosis. Various clinical and epidemiological markers have facilitated decision-making with respect to therapy but no single molecular biomarker has been shown to enhance prediction of disease progression. The publication of the canine genome in 2005 raised the possibility of increasing understanding of the genetic mechanisms underpinning canine OS. This review explores the use of biomarkers within the multi-disciplinary management of dogs with OS, and highlights the few known, potential prognostic/predictive molecular markers including their potential value as 'bridging biomarkers' for human OS. Although high-throughput profiling of canine OS remains in its infancy, research within the next decade using leading-edge screening technologies has the potential to identify biomarkers that may enhance diagnostic and prognostic accuracy and result in more effective, individually tailored, treatment and management protocols for affected dogs.

Serum cardiac troponin I concentration in retired racing greyhounds

BACKGROUND

Cardiac troponin I (cTnI) is a polypeptide found specifically in cardiac muscle tissue that has been used as a diagnostic and prognostic indicator of cardiomyopathy. Increases in cTnI are associated with myocardial pathologic processes. However, high serum cTnI concentrations have been observed in normal Greyhounds.

HYPOTHESIS

We hypothesized that Greyhounds have cTnI concentrations higher than non-Greyhound dogs, and that a separate reference range should be established for Greyhounds.

ANIMALS

Blood samples were collected from the jugular vein from a group of 20 healthy Greyhound blood donors.

METHODS

Analysis of serum cTnI was performed with an immunoassay system with a detection level of 0.01 ng/mL, as described previously. The Greyhound values were compared with 2 groups of Boxers with and without arrhythmogenic right ventricular cardiomyopathy (ARVC), and to a group of non-Boxer control dogs from a previous study.

RESULTS

The mean cTnI concentration in Greyhounds was significantly higher (P < .0001) than that in non-Greyhound control dogs, although not significantly different from normal Boxers (P= .50), or Boxers with ARVC (P= .58). Greyhound serum cTnI concentrations were in the range found in Boxers with ARVC. The proposed reference range for cTnI in Greyhounds is 0.05-0.16 ng/mL.

CONCLUSIONS AND CLINICAL IMPORTANCE

Greyhounds have a reference range for serum cTnI concentrations that differs from that of other previously published reference ranges for dogs of other breeds. Until a broader database and more precise reference range can be established, caution should be exercised in interpreting serum cTnI concentrations in Greyhounds with suspected cardiac disease.

Assessment of plasma cardiac troponin I concentration as a means to differentiate cardiac and noncardiac causes of dyspnea in cats

OBJECTIVE

To determine whether plasma cardiac troponin I (cTnI) concentrations can be used to discriminate cardiac from noncardiac causes of dyspnea in cats.

DESIGN

Prospective, multicenter study.

ANIMALS

Client-owned cats with dyspnea attributable to congestive heart failure (D-CHF; n=31) or to noncardiac causes (D-NCC; n=12).

PROCEDURES

For each cat, plasma cTnI concentration was analyzed by use of a solid-phase radial partition immunoassay; values in cats with D-CHF and D-NCC were compared. A receiver operating characteristic curve was analyzed to determine the accuracy of plasma cTnI concentration for diagnosis of D-CHF.

RESULTS

Median plasma concentration of cTnI in cats with D-CHF (1.59 ng/mL; range, 0.20 to 30.24 ng/mL) was significantly higher than in cats with D-NCC (0.165 ng/mL; range, 0.01 to 1.42 ng/mL). With regard to the accuracy of plasma cTnI concentration for diagnosis of D-CHF, the area under the receiver operating characteristic curve was 0.84. At plasma concentrations > or = 0.2 ng/mL, cTnI had 100% sensitivity but only 58% specificity for identification of CHF as the cause of dyspnea. At plasma concentrations > or = 1.43 ng/mL, cTnI had 100% specificity and 58% sensitivity for identification of CHF as the cause of dyspnea.

CONCLUSIONS AND CLINICAL RELEVANCE

On the basis of the derived diagnostic limits, CHF as the cause of dyspnea could be ruled in or ruled out without additional diagnostic testing in > 50% of the study cats. Measurement of plasma cTnI concentration may be clinically useful for differentiation of cardiac from noncardiac causes of dyspnea in cats. (J Am Vet

Epirubicin in the adjuvant treatment of splenic hemangiosarcoma in dogs: 59 cases (1997-2004)

OBJECTIVE

To determine the efficacy and toxic effects of epirubicin for the adjuvant treatment of dogs with splenic hemangiosarcoma and identify prognostic factors.

DESIGN

Retrospective case series.

ANIMALS

59 client-owned dogs that underwent splenectomy for splenic hemangiosarcoma treated with or without epirubicin.

PROCEDURES

Medical records were examined for signalment, clinical signs, diagnostic and surgical findings, and postoperative outcome. For dogs treated with epirubicin, dose numbers, intervals, and reductions and type and severity of toxic effects were recorded. Dogs were allotted to 2 groups: splenectomy alone and splenectomy with adjuvant epirubicin treatment.

RESULTS

18 dogs received epirubicin (30 mg/m(2)) every 3 weeks for up to 4 to 6 treatments. Forty-one dogs were treated with splenectomy alone. The overall median survival time was significantly longer in dogs treated with splenectomy and epirubicin (144 days), compared with splenectomy alone (86 days). Median survival time for dogs with stage I disease (345 days) was significantly longer than for dogs with either stage II (93 days) or III disease (68 days). Seven of 18 dogs treated with epirubicin were hospitalized for signs of adverse gastrointestinal effects. Inappetence, long duration of clinical signs, thrombocytopenia, neutrophilia, and high mitotic rate were negative prognostic factors.

CONCLUSIONS AND CLINICAL RELEVANCE

Epirubicin may be as efficacious as adjuvant doxorubicin-based protocols, but may result in a higher incidence of adverse gastrointestinal effects. Epirubicin should be considered as an alternative to doxorubicin in dogs with preexisting cardiac disease, as clinical epirubicin cardiotoxicity was not diagnosed in treated dogs.

Cardiac troponin is the most effective translational safety biomarker for myocardial injury in cardiotoxicity

There is an overwhelming weight of evidence that certifies cardiac troponin (cTn) as the preferred, defacto, translational, safety biomarker for myocardial injury in cardiotoxicity. As well as being the gold standard for cardiac injury in man, it has been widely used for clinical assessment and monitoring of cardiac toxicity in humans being treated for cancer. Furthermore, several dozen preclinical published studies have directly confirmed its effectiveness in laboratory animals for assessment of cardiotoxicity. It is gradually being reverse translated from human into animal use as a safety biomarker. Its use is especially merited whenever there is any safety signal indicating potential cardiotoxicity and its required inclusion as a routine biomarker in preclinical safety studies seems on the horizon. There are some considerations that are unique to use of cTn assays in animals. Lack of awareness of these has, historically, significantly inhibited the introduction of cTn as a safety biomarker in preclinical toxicology. Firstly, cross-species reactivity is usually but not always high. Secondly, there is a background of cardiac injury that needs to be controlled for, including spontaneous cardiomyopathy in Sprague Dawley rats, and inappropriate blood collection methods. Also, there are faster kinetics of clearance in rats than for humans. Also, coincident muscle injury is frequent with cardiotoxicity and requires a skeletal muscle biomarker. Because cTn assays were developed for detection of gross cardiac necrosis, such as occurs with myocardial infarct, the more sensitive assays should be used for preclinical studies. However, analytic sensitivity is higher for standard preclinical studies than for clinical diagnostic testing because of use of concurrent controls and use of batch analysis that eliminates interassay variability. No other biomarker of myocardial injury comes close to cTn in effectiveness, including CK-MB, LDH-1 and 2, myoglobin, and FABP3. In addition to the use of cTn for monitoring active myocardial degeneration, there is growing evidence that measurements of brain natriuretic peptide (BNP) may be effective for monitoring drug-induced left ventricular dysfunction.

Evaluation of serum cardiac troponin I concentration in Boxers with arrhythmogenic right ventricular cardiomyopathy

OBJECTIVE

To evaluate serum cardiac troponin I (cTnI) concentrations in Boxers with arrhythmogenic right ventricular cardiomyopathy (ARVC), unaffected (control) Boxers, and control non-Boxers.

ANIMALS

10 Boxers with a clinical diagnosis of ARVC defined by > or = 1,000 ventricular premature complexes (VPCs)/24 h on an ambulatory ECG, 10 control Boxers assessed as normal by the presence of < 5 VPCs/24h, and 10 control non-Boxers.

PROCEDURES

Serum was extracted from a blood sample from each dog. Analysis of serum cTnI concentrations was performed.

RESULTS

Mean +/- SD serum cTnI concentration was 0.142 +/- 0.05 ng/mL for Boxers with ARVC, 0.079 +/- 0.03 ng/mL for control Boxers, and 0.023 +/- 0.01 ng/mL for control non-Boxers. A significant difference in serum cTnI concentrations was observed among the 3 groups. In the combined Boxer population (ie, Boxers with ARVC and control Boxers), a significant correlation was found between serum cTnI concentration and number of VPCs/24 h (r = 0.78) and between serum cTnI concentration and grade of ventricular arrhythmia (r = 0.77).

CONCLUSIONS AND CLINICAL RELEVANCE

Compared with clinically normal dogs, Boxers with ARVC had a significant increase in serum cTnI concentration. For Boxers, correlations were found between serum cTnI concentration and number of VPCs/24 h and between concentration and the grade of arrhythmia. Because of the overlap in serum cTnI concentrations in control Boxers and Boxers with ARVC, future studies should evaluate the correlation of serum cTnI concentration with severity of disease in terms of degree of myocardial fibrofatty changes.

Neurohormonal, hemodynamic, and electrocardiographic evaluations of healthy dogs receiving long-term administration of doxorubicin

OBJECTIVE

To evaluate diagnostic testing that could be used to establish an early diagnosis of cardiotoxicosis induced by long-term administration of doxorubicin.

ANIMALS

13 adult mixed-breed dogs. Procedures-7 dogs were administered doxorubicin chloride (30 mg/m(2), IV, q 21 d for 168 days [cumulative dose, 240 mg/m(2)]), and 6 dogs received saline (0.9% NaCl) solution (5 mL, IV, q 21 d for 168 days; control group). Echocardiography, ECG, arterial blood pressure, plasma renin activity (PRA), and plasma concentrations of norepinephrine and brain natriuretic peptide (BNP) were assessed before each subsequent administration of doxorubicin and saline solution.

RESULTS

Dogs that received doxorubicin had a significant decrease in R-wave amplitude, compared with values for the control group, from 30 to 210 mg/m(2). Doxorubicin-treated dogs had decreases in fractional shortening and left ventricular ejection fraction evident as early as 30 mg/m(2), but significant differences between groups were not detected until 90 mg/m(2)was reached. There was also a significant increase in PRA (>or= 120 mg/m(2)) and left ventricular end-systolic and end-diastolic dimensions (>or= 60 and >or= 180 mg/m(2), respectively). Systemic arterial pressure, remaining echocardiographic variables, and concentrations of norepinephrine and BNP had significant variations, but of no clinical importance, during doxorubicin administration.

CONCLUSIONS AND CLINICAL RELEVANCE

Doxorubicininduced cardiotoxicosis developed at 120 mg/m(2), but there were no clinical signs of dilated cardiomyopathy or congestive heart failure. Echocardiography and determination of PRA were able to detect early cardiac alterations during the development of dilated cardiomyopathy, despite apparently differing degrees of sensitivity to development of doxorubicin-induced cardiotoxicosis.