Dilated cardiomyopathy of possible dietary origin in a cat

An 11-year-old spayed female domestic shorthaired cat was diagnosed with severe dilated cardiomyopathy (DCM) and congestive heart failure. The cat had been eating cat foods that were high in pulses (e.g. peas, lentils, chickpeas). Neither plasma nor whole blood taurine concentrations were deficient. Primary treatment included furosemide, pimobendan, and clopidogrel, and changing to diets that did not contain pulses (a taurine supplements was not administered). The cat's clinical signs improved, high-sensitivity cardiac troponin I concentrations decreased, and echocardiographic measurements stayed relatively stable for over one year after initiating cardiac medications and changing the diet. Ultimately, the cat was euthanized for worsening congestive heart failure 374 days after the diagnosis of DCM. Infectious disease testing during the time of clinical surveillance was negative. Routine histopathology of the heart was unremarkable, but electron microscopy of the left ventricle showed large numbers of mitochondria of variable size and structure. A moderate number of lamellar bodies and autophagic vacuoles also were noted. This case report illustrates an unusual case of a cat with DCM unrelated to taurine deficiency. The relative roles of diet change, cardiac medications, and a dedicated owner are unclear, but this cat's relatively long survival time is similar to that seen after diet change in dogs and cats with DCM eating high-pulse diets.

Dilated cardiomyopathy in cats: survey of veterinary cardiologists and retrospective evaluation of a possible association with diet

INTRODUCTION/OBJECTIVES

The objectives were to conduct a survey of cardiologists on their recent experiences with cats that have dilated cardiomyopathy (DCM) and to retrospectively review individual cases of feline DCM.

ANIMALS, MATERIALS AND METHODS

Part one: A survey was distributed to cardiologists with questions regarding caseload and clinical management of cats with DCM diagnosed over the past two years. Part two: Cardiologists completing the survey were invited to submit data from cats recently diagnosed with DCM. Data on signalment, clinical signs, diet, echocardiographic measurements and outcome were recorded.

RESULTS

Part one: From 52 completed surveys, many cardiologists responded that measuring and supplementing taurine and recommending a diet change in cats with DCM are common practices. Few (15%) cardiologists reported an increase in the number of feline DCM cases over the past two years, although some had cases that improved even if taurine deficiency was not present. Part two: Twenty of 37 (54%) cats ate low pea/lentil (low PL) diets, and 14/37 (38%) ate high PL diets at the time of diagnosis; three had incomplete diet information. Two of 13 cats (15%) in which taurine was measured had levels below the reference range. After adjusting for other variables, cats eating high PL diets that changed diets after diagnosis had a significantly longer survival time than that of cats eating high PL diets that did not change diets after diagnosis (P = 0.025).

CONCLUSIONS

Additional research is warranted to determine whether there could be a possible association between diet and DCM in cats.

Plasma growth differentiation factors 8 and 11 levels in cats with congestive heart failure secondary to hypertrophic cardiomyopathy

OBJECTIVES

Growth differentiation factor (GDF) 11 has been shown to reduce cardiac hypertrophy in mice. Low levels of GDF-11 are associated with cardiac hypertrophy in humans. The authors hypothesized that plasma GDF-11 level is decreased in cats with hypertrophic cardiomyopathy (HCM). Given the close homology between GDF-11 and myostatin/GDF-8, GDF-8 levels were also assessed.

ANIMALS

Thirty-seven client-owned cats were enrolled, including cats with normal cardiac structure (n = 16), cats with HCM or hypertrophic obstructive cardiomyopathy (HOCM; n = 14), and cats with HCM and congestive heart failure (CHF; n = 7).

METHODS

Plasma samples were analyzed for GDF-8 and GDF-11 using liquid chromatography tandem-mass spectrometry. Levels of GDF-8 and GDF-11 were compared between cats with normal cardiac structure, HCM or HOCM, and CHF.

RESULTS

No differences in GDF-11 concentrations were found between cats with normal cardiac structure and cats with HCM/HOCM, with or without history of CHF. Decreased GDF-8 concentrations were detected in cats with CHF compared to cats with HCM/HOCM without history of CHF (p=0.031) and cats with normal cardiac structure (p=0.027). Growth differentiation factor 8 was higher in cats with HOCM compared to those with CHF (p=0.002). No statistical difference was noted in GDF-8 level as a function of age, weight, or body condition score.

CONCLUSIONS

Plasma GDF-11 was not different between cats with HCM/HOCM and cats with normal cardiac structure regardless of age. Plasma GDF-8 was decreased in cats with CHF compared to cats with normal cardiac structure and cats with asymptomatic HCM/HOCM, suggesting a possible role in CHF development.

Synchronous diaphragmatic contraction associated with dual-chamber transvenous pacing in a dog

A 3-year-old, 20-kg, spayed female, mix-breed dog received a dual-chamber pacemaker for management of symptomatic 3rd-degree atrioventricular block. Synchronous diaphragmatic contraction was documented to occur with atrial pacing. Various methods to reduce the occurrence of pacemaker-related phrenic nerve stimulation are discussed.

Association between Survival Time and Changes in NT-proBNP in Cats Treated for Congestive Heart Failure

Background

Reductions in N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) concentrations after treatment have been associated with improved survival in people with congestive heart failure (CHF), but have not been reported in cats with CHF.

Objectives

To evaluate changes in NT‐proBNP concentrations in cats with CHF after treatment and determine whether serial NT‐proBNP measurements provide prognostic information.

Animals

Thirty‐one client‐owned cats.

Methods

Prospective, observational study in cats with new onset CHF secondary to cardiomyopathy. Concentrations of NT‐proBNP were measured within 4 hours of admission to the hospital, on the day of discharge, and at re‐evaluation 7–10 days later.

Results

Median NT‐proBNP concentrations decreased significantly from admission (1,713 pmol/L [range, 160–3,784 pmol/L]) to discharge (902 pmol/L [range, 147–3,223 pmol/L]); P = .005) and from admission to re‐evaluation (1,124 pmol/L [range, 111–2,727 pmol/L]; P = .024). Median survival time was 109 days (range, 1–709 days), with 5 cats still alive at the time of analysis. Cats with a larger percent decrease in NT‐proBNP from admission to discharge had a longer survival time (P = .048). Cats with evidence of active CHF at the time of re‐evaluation (P = .010) and cats whose owners had difficulty administering medications (P = .045) had shorter survival times.

Conclusions and clinical importance

Cats with a larger percent decrease in NT‐proBNP during hospitalization and no evidence of CHF at the time of re‐evaluation had longer survival times. Additional studies are needed to determine whether NT‐proBNP can help guide treatment in cats with CHF.

Differentiation of Cardiac from Noncardiac Pleural Effusions in Cats using Second-Generation Quantitative and Point-of-Care NT-proBNP Measurements

Background

Pleural effusion is a common cause of dyspnea in cats. N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) measurement, using a first‐generation quantitative ELISA, in plasma and pleural fluid differentiates cardiac from noncardiac causes of pleural effusion.

Hypothesis/Objectives

To determine whether NT‐proBNP measurements using second‐generation quantitative ELISA and point‐of‐care (POC) tests in plasma and pleural fluid distinguish cardiac from noncardiac pleural effusions and how results compare to the first‐generation ELISA.

Animals

Thirty‐eight cats (US cohort) and 40 cats (UK cohort) presenting with cardiogenic or noncardiogenic pleural effusion.

Methods

Prospective cohort study. Twenty‐one and 17 cats in the US cohort, and 22 and 18 cats in the UK cohort were classified as having cardiac or noncardiac pleural effusion, respectively. NT‐proBNP concentrations in paired plasma and pleural fluid samples were measured using second‐generation ELISA and POC assays.

Results

The second‐generation ELISA differentiated cardiac from noncardiac pleural effusion with good diagnostic accuracy (plasma: sensitivity, 95.2%, specificity, 82.4%; pleural fluid: sensitivity, 100%, specificity, 76.5%). NT‐proBNP concentrations were greater in pleural fluid (719 pmol/L (134–1500)) than plasma (678 pmol/L (61–1500), P = 0.003), resulting in different cut‐off values depending on the sample type. The POC test had good sensitivity (95.2%) and specificity (87.5%) when using plasma samples. In pleural fluid samples, the POC test had good sensitivity (100%) but low specificity (64.7%). Diagnostic accuracy was similar between first‐ and second‐generation ELISA assays.

Conclusions and clinical importance

Measurement of NT‐proBNP using a quantitative ELISA in plasma and pleural fluid or POC test in plasma, but not pleural fluid, distinguishes cardiac from noncardiac causes of pleural effusion in cats.

Relationship of body size to metabolic markers and left ventricular hypertrophy in cats

BACKGROUND

Cats with hypertrophic cardiomyopathy (HCM) are larger and have higher insulin-like growth factor-1 (IGF-1) concentrations than cats without HCM.

HYPOTHESIS/OBJECTIVES

The aim of this study was to assess echocardiographic findings in a colony of adult cats to determine the relationship between early growth and left ventricular hypertrophy (LVH).

ANIMALS

Twenty-eight neutered adult cats (20 males, 8 females) from a colony ≥ 3 years of age for which growth curves were available.

METHODS

Case-control study. Physical examination and echocardiography were performed, and body weight, body condition score (BCS), and head length and width were measured. Circulating glucose, insulin, N-terminal pro-B-type natriuretic peptide (NT-proBNP), and IGF-1 concentrations were measured and growth data were collected. Stepwise multivariate analyses were performed.

RESULTS

Mean age was 5.2 ± 1.1 years. Current BCSs ranged from 4 to 9 (median, 6) and mean body weight was 4.88 ± 1.29 kg. Variation in body weight was apparent by 6 (mean = 3.26 ± 0.80 kg) and 12 months of age (mean = 4.02 ± 1.02 kg). Cardiac abnormalities included a cardiac murmur (n = 7; 24%), gallop (n = 3; 10%), and arrhythmia (n = 1; 4%). Fourteen of 28 cats (50%) had echocardiographic evidence of LVH. Head width (P = .017), body weight (P < .001), NT-proBNP (P = .023), and IGF-1 (P = .013-.022) were significantly associated with selected measures of LVH.

CONCLUSIONS AND CLINICAL IMPORTANCE

Potential associations between body size, IGF-1, LVH, and HCM warrant future prospective studies.

Relationship of plasma N-terminal pro-brain natriuretic peptide concentrations to heart failure classification and cause of respiratory distress in dogs using a 2nd generation ELISA assay

Background

Cardiac biomarkers provide objective data that augments clinical assessment of heart disease (HD).

Hypothesis/Objectives

Determine the utility of plasma N‐terminal pro‐brain natriuretic peptide concentration [NT‐proBNP] measured by a 2nd generation canine ELISA assay to discriminate cardiac from noncardiac respiratory distress and evaluate HD severity.

Animals

Client‐owned dogs (n = 291).

Methods

Multicenter, cross‐sectional, prospective investigation. Medical history, physical examination, echocardiography, and thoracic radiography classified 113 asymptomatic dogs (group 1, n = 39 without HD; group 2, n = 74 with HD), and 178 with respiratory distress (group 3, n = 104 respiratory disease, either with or without concurrent HD; group 4, n = 74 with congestive heart failure [CHF]). HD severity was graded using International Small Animal Cardiac Health Council (ISACHC) and ACVIM Consensus (ACVIM‐HD) schemes without knowledge of [NT‐proBNP] results. Receiver‐operating characteristic curve analysis assessed the capacity of [NT‐proBNP] to discriminate between dogs with cardiac and noncardiac respiratory distress. Multivariate general linear models containing key clinical variables tested associations between [NT‐proBNP] and HD severity.

Results

Plasma [NT‐proBNP] (median; IQR) was higher in CHF dogs (5,110; 2,769–8,466 pmol/L) compared to those with noncardiac respiratory distress (1,287; 672–2,704 pmol/L; P < .0001). A cut‐off >2,447 pmol/L discriminated CHF from noncardiac respiratory distress (81.1% sensitivity; 73.1% specificity; area under curve, 0.84). A multivariate model comprising left atrial to aortic ratio, heart rate, left ventricular diameter, end‐systole, and ACVIM‐HD scheme most accurately associated average plasma [NT‐proBNP] with HD severity.

Conclusions and Clinical Importance

Plasma [NT‐proBNP] was useful for discriminating CHF from noncardiac respiratory distress. Average plasma [NT‐BNP] increased significantly as a function of HD severity using the ACVIM‐HD classification scheme.

A randomized study assessing the effect of diet in cats with hypertrophic cardiomyopathy

Background

Diet might influence progression of hypertrophic cardiomyopathy (HCM).

Objective

To investigate whether diet composition could alter clinical, biochemical, or echocardiographic variables in cats with HCM.

Animals

Twenty‐nine cats with HCM (International Small Animal Cardiac Health Council stage 1b) examined at a university teaching hospital.

Methods

Randomized, placebo‐controlled trial. After physical examination, echocardiogram, and blood collection, cats were randomized to 1 of 3 diets, which varied in carbohydrate and fat content and ingredients. Measurements were repeated after 6 months.

Results

There were no significant differences among the 3 groups at baseline. After 6 months, there were no significant changes in the primary endpoints, left ventricular free wall (Group A, P = .760; Group B, P = .475; Group C, P = .066) or interventricular septal thickness in diastole (Group A, P = .528; Group B, P = .221; Group C, P = .097). Group A had significant increases in BUN (P = .008) and cholesterol (P = .021), while Group B had significant increases in BUN (P = .008), cholesterol (P = .007), and triglycerides (P = .005), and significant decreases in NT‐proBNP (P = .013) and hs‐troponin I (P = .043). Group C had significant decreases in body weight (P = .021), left atrial dimension (P = .035), interventricular septal thickness in systole (P = .038), and liver enzymes (P = .034–.038).

Conclusions and Clinical Importance

These data suggest that diet might influence some clinical, biochemical, and echocardiographic variables in cats with HCM.

Effect of NT-pro-BNP assay on accuracy and confidence of general practitioners in diagnosing heart failure or respiratory disease in cats with respiratory signs

BACKGROUND

N-terminal pro-B-type natriuretic peptide (NT-proBNP) can distinguish congestive heart failure (CHF) from primary respiratory disease in cats with respiratory signs with approximately 90% diagnostic accuracy, but the additive benefit of NT-proBNP to improve the diagnosis obtained from conventional testing in individual cases remains unknown.

HYPOTHESIS

NT-proBNP will improve the diagnostic accuracy and confidence of general practice veterinarians in assessing cats with respiratory signs.

ANIMALS

Ten cats with respiratory signs.

METHODS

History, physical examination, thoracic radiographs, electrocardiogram (ECG), and biochemical analysis of 10 cats presented to the University of Pennsylvania or Tufts University with a history of respiratory signs were evaluated by 50 general practice veterinarians using an online survey tool. Participants were asked to provide (1) diagnosis of CHF or primary respiratory disease, and (2) level of confidence in their diagnosis (1, lowest to 10, highest) before and after disclosure of NT-proBNP results. Diagnoses (CHF, n = 5; primary respiratory, n = 5) were compared to the gold standard defined as consensus opinion of 3 board-certified cardiologists blinded to the NT-proBNP results.

RESULTS

Overall correctness of the practitioners was 69.2%, and significantly increased after practitioners were provided NT-proBNP results (87.0%, P = .0039). Median practitioner confidence before NT-proBNP disclosure was 6 (IQR, 5-8) and significantly increased after disclosure (8; IQR, 6-10; P = .0039).

CONCLUSIONS

These data indicate a relatively low accuracy and level of confidence in the diagnosis of feline respiratory signs. Use of NT-proBNP assay in conjunction with conventional evaluation by general practitioners significantly improved their diagnostic accuracy and confidence.

Echocardiographic ratio indices in overtly healthy Boxer dogs screened for heart disease

BACKGROUND

Boxer dogs are routinely screened by echocardiography to exclude congenital and acquired heart disease. Individuals of a given breed may span a large range of body sizes, potentially invalidating linear regression of M-mode measurements against body weight. Echocardiographic ratio indices (ERIs) provide a novel method of characterizing echocardiographic differences between Boxers and other dog breeds.

HYPOTHESIS

ERIs obtained from overtly healthy Boxer dogs presented for cardiac screening will be different from ERIs established for normal non-Boxer dogs, and those differences will be unrelated to aortic velocity or systolic blood pressure.

ANIMALS

Eighty-one Boxers with no outward clinical signs of heart disease were studied.

METHODS

All dogs were examined by 2-dimensional, M-mode, and Doppler echocardiography. M-mode measurements were used to perform ERI calculations, and the indices in Boxers were compared between Boxers with varying severity of arrhythmia and those of normal non-Boxer dogs.

RESULTS

Differences in weight-based ERIs, which reflect increased thickness of the left ventricular free wall (LVW) and interventricular septum (IVS) and smaller aortic size, were found in overtly healthy Boxer dogs compared with normal non-Boxer dogs. ERIs of left atrial and LV cavity size in overtly healthy Boxers were not significantly different from those of non-Boxer dogs.

CONCLUSIONS AND CLINICAL IMPORTANCE

Boxer dogs may have an increased relative thickness of the LVW and IVS that is independent of aortic size, aortic velocity, or arterial blood pressure, and this morphology should be taken into consideration when screening Boxers by echocardiography.

Infantile dilated cardiomyopathy in Portuguese water dogs: Correlation of the autosomal recessive trait with low plasma taurine at infancy

Infantile dilated cardiomyopathy (IDCM) in Portuguese water dogs (PWD) involves an autosomal recessive trait. Based on our previous studies we have tested the hypothesis that this disorder may be correlated with taurine deficiency. The plasma taurine levels of 249 puppies from 36 litters obtained from breeders at six and nine weeks of age, an early stage when usually the clinical symptoms are not manifested, were analyzed. Additional samples were collected from sixteen puppies that we raised from four litters. These litters were born to a dam that had low plasma taurine as a puppy and two known carrier sires. From the random samples obtained from the breeders, forty-eight pups from fourteen litters and twenty-nine pups from seven litters had low plasma taurine at least at one and at two time points, respectively. Also several puppies showing low plasma taurine died due to IDCM. Furthermore, from the sixteen pups we raised, fifteen had at least low taurine level at one and seven had at two time points. Considered together, these results strongly support the view that IDCM in PWD is associated with abnormal taurine metabolism that leads to low plasma taurine at early stages before the clinical symptoms appear.

Prevalence and prognostic importance of hypomagnesemia and hypocalcemia in horses that have colic surgery

OBJECTIVE

To determine the prevalence of hypomagnesemia and hypocalcemia in horses with surgical colic.

ANIMALS

35 horses with surgically managed colic.

PROCEDURE

Serum concentrations of total magnesium (tMg2+) and calcium (tCa2+), as well as ionized magnesium (iMg2+) and calcium (iCa2+) were analyzed before surgery and 1, 3, 5, and 7 days following surgery. A lead-II ECG and pertinent clinical data were also obtained at each time.

RESULTS

Preoperative serum tMg2+ and iMg2+ concentrations were below the reference range in 6 (17%) and 19 (54%) horses, respectively. Serum concentrations of tCa2+ and iCa2+ were less than the reference range in 20 (57%) and 30 (86%) horses before surgery. Horses with strangulating lesions of the gastrointestinal tract had significantly lower preoperative serum concentrations of iMg2+ and iCa2+, as well as a higher heart rate than horses with nonstrangulating lesions. Horses that developed postoperative ileus had significantly lower serum concentrations of iMg2+ after surgery. Serum concentrations of magnesium and calcium (total and ionized) correlated significantly with the PR, QRS, QT, and corrected QT (QTc) intervals. Horses that were euthanatized at the time of surgery (n = 7) had significantly lower preoperative serum concentrations of iMg2+, compared with horses that survived. Neither serum magnesium nor calcium concentrations were predictors of hospitalization time or survival.

CONCLUSIONS AND CLINICAL RELEVANCE

Hypomagnesemia and hypocalcemia were common during the perioperative period, particularly in horses with strangulating intestinal lesions and ileus. Serum concentrations of tMg2+ and tCa2+ were less sensitive than iMg2+ and iCa2+ in detecting horses with hypomagnesemia and hypocalcemia.

Relationship between circulating and dietary taurine concentrations in dogs with dilated cardiomyopathy

A retrospective study was conducted to determine dietary taurine concentrations in dogs with dilated cardiomyopathy (DCM) and to compare the clinical outcome of taurine-deficient and non-taurine-deficient dogs. Taurine concentrations were low in blood samples from 20 of 37 dogs with DCM. Median dietary taurine concentration was not significantly different between taurine-deficient and nondeficient dogs. There was no correlation between dietary and circulating taurine concentrations. The outcome of taurine-deficient dogs supplemented with taurine was not different from the outcome of nondeficient dogs. The role oftaurine and its relationship to dietary intake in canine DCM remain unclear.

Inherited infantile dilated cardiomyopathy in dogs: genetic, clinical, biochemical, and morphologic findings

Dilated cardiomyopathy, a lethal disease characterized by left ventricular dilation and systolic dysfunction, is relatively common in humans and other mammals. Idiopathic dilated cardiomyopathy (IDCM) is a primary myocardial disease of unknown cause and can be a familial disorder. This report describes autosomal recessive IDCM in dogs. It occurs in Portuguese Water Dog (PWD) pups and is manifested by acute, vague clinical signs and sudden death. Affected pups have progressive reduction of fractional shortening that can be demonstrated by echocardiography prior to the development of clinical signs. Furthermore, these pups have low plasma taurine levels when consuming certain diets. Affected pups had dilation of the left ventricle and alterations in the sarcomere appearance, while immunohistochemical and biochemical studies demonstrate an increase in desmin, a cytoskeleton protein. The clinical and morphologic findings of IDCM in PWDs are distinct from those reported in adult IDCM. Finally, the clinical and echocardiographic manifestations were reversible in some pups following oral taurine supplementation for 2 months. These results suggest that IDCM in PWDs is correlated with low plasma taurine levels.

Plasma homocysteine, B vitamins, and amino acid concentrations in cats with cardiomyopathy and arterial thromboembolism

Arterial thromboembolism (ATE) is a common complication of cats with cardiomyopathy (CM), but little is known about the pathophysiology of ATE. In people, high plasma concentrations of homocysteine and low B vitamin concentrations are risk factors for peripheral vascular disease. In addition, low plasma arginine concentrations have been linked to endothelial dysfunction. The purpose of this study was to compare concentrations of homocysteine, B vitamins, and amino acids in plasma of normal cats to those of cats with CM and ATE. Plasma concentrations of homocysteine, vitamin B6, vitamin B12, folate, and amino acids were measured in 29 healthy cats, 27 cats with CM alone, and 28 cats with both CM and ATE. No differences were found between groups in homocysteine or folate. Mean vitamin B12 concentration (mean +/- standard deviation) was lower in cats with ATE (866 +/- 367 pg/mL) and cats with CM (939 +/- 389 pg/mL) compared with healthy controls (1,650 +/- 700 pg/mL; P < .001). Mean vitamin B6 concentration was lower in cats with ATE (3,247 +/- 1.215 pmol/mL) and cats with CM (3,200 +/- 906 pmol/mL) compared with healthy control animals (4,380 +/- 1,302 pmol/mL; P = .005). Plasma arginine concentrations were lower in cats with ATE (75 +/- 33 nmol/mL) compared with cats with CM (106 +/- 25 nmol/mL) and healthy control animals (96 +/- 25 nmol/ mL; P < .001). Vitamin B12 concentration was significantly correlated with left atrial size. We interpret the results of this study to suggest that vitamin B12 and arginine may play a role in CM and ATE of cats.

Clinical, echocardiographic, and neurohormonal effects of a sodium-restricted diet in dogs with heart failure

The use of low-sodium diets in dogs with heart failure is common practice, but randomized, double-blind studies have not been conducted to examine the benefits or problems with this approach. The purpose of this study was to determine the effects of a low-sodium diet on clinical, echocardiographic, and neurohormonal parameters in dogs with heart failure. Dogs with stable chronic heart failure were fed exclusively a low-sodium (LS) and a moderate-sodium (MS) diet for 4 weeks each in a randomized, double-blind, crossover design. At days 0, 28, and 56, echocardiography and thoracic radiography were performed, and blood was analyzed for electrolytes and neurohormones. Fourteen dogs completed the study (9 with chronic valvular disease and 5 with dilated cardiomyopathy). Electrolyte abnormalities were common during the study, and serum sodium and chloride concentrations decreased significantly on the LS diet. Neurohormones did not change significantly between diet groups. Maximum left atrial (P = .05) and standard left atrial (P = .09) size decreased on the LS diet. For dogs with chronic valvular disease, vertebral heart score (P = .05), left ventricular internal dimension in diastole (P = .006) and systole (P = .02), standard left atrial dimension (P = .03), maximum left atrial dimension (P = .02), end-diastolic volume index (P = .02), and end-systolic volume index (P = .04) decreased significantly on the LS diet compared to the MS diet. Although analysis of these data suggests some benefits of a low-sodium diet, future studies with improved study design are needed to further evaluate the advantages and disadvantages of sodium restriction in dogs with heart failure.

Assessment of degree of oxidative stress and antioxidant concentrations in dogs with idiopathic dilated cardiomyopathy

OBJECTIVE

To assess degree of oxidative stress and antioxidant concentrations in dogs with idiopathic dilated cardiomyopathy (IDCM).

DESIGN

Prospective study.

ANIMALS

18 dogs with IDCM and 16 healthy control dogs.

PROCEDURE

Concentrations of malondialdehyde (an indicator of oxidative stress); vitamins A, C, and E; glutathione peroxidase; and superoxide dismutase were measured.

RESULTS

Glutathione peroxidase concentration was significantly increased in dogs with IDCM, compared with control dogs. Vitamin A and superoxide dismutase concentrations were not significantly different between groups. A negative correlation was found between disease severity and plasma vitamin E concentration. Disease severity was not correlated with concentrations of other antioxidants. Medications did not significantly affect oxidant or antioxidant concentrations.

CONCLUSIONS AND CLINICAL RELEVANCE

The change in glutathione peroxidase concentration and the correlation between vitamin E concentration and disease severity suggest that the oxidant-antioxidant system may play a role in development of IDCM.

Factors contributing to the decision for euthanasia of dogs with congestive heart failure

OBJECTIVE

To determine the prevalence of clinical signs that affect quality of life in dogs with congestive heart failure (CHF), and to characterize the role of these clinical signs in the decision for euthanasia.

DESIGN

Prospective study.

ANIMALS

38 dogs with CHF that had been euthanatized within the preceding 22 months.

PROCEDURE

Clinical information and factors affecting the decision for euthanasia were reviewed and recorded from medical records of dogs with CHF. Each owner was then interviewed via telephone to determine whether their dog had anorexia or other clinical signs of disease prior to euthanasia, their perception of their dogs' quality of life, and the most important factor and contributing factors that influenced the decision to euthanatize their dog.

RESULTS

Of the 38 dogs with CHF, > 70% had weakness (35 dogs), coughing (33), anorexia (32), weight loss (32), dyspnea (30), or exercise intolerance (28) reported by their owners. Factors often named by owners as most important in the decision for euthanasia were poor prognosis given by the attending veterinarian, recurrent clinical signs of CHF (ie, coughing, dyspnea, or ascites), and poor quality of life. Weakness, anorexia, and recurrent clinical signs of CHF were the most common contributing factors in the decision for euthanasia.

CLINICAL IMPLICATIONS

Anorexia, weight loss, and exercise intolerance are common in dogs euthanatized because of CHF. The importance of quality of life and poor prognosis in making a decision for euthanasia suggests that addressing these factors may improve patient management.

Therapy of feline hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common form of feline heart disease. Affected cats have concentrical or asymmetrical left ventricular hypertrophy without an identifiable cause. Although many diseases can cause concentrical left ventricular hypertrophy, the term hypertrophic cardiomyopathy is used here exclusively to refer to the idiopathic disease.

Nutritional alterations and the effect of fish oil supplementation in dogs with heart failure

Alterations in body composition and nutritional status are common in humans with heart failure and are related, in part, to increases in cytokine concentrations. Cytokines have not been studied previously in dogs with naturally occurring cardiac disease nor has fish oil administration been used in this population to decrease cytokine production. The purposes of this study were to characterize nutritional and cytokine alterations in dogs with heart failure and to test the ability of fish oil to reduce cytokines and improve clinical outcome. Body composition, insulinlike growth factor-1, fatty acids, and cytokines were measured in 28 dogs with heart failure and in 5 healthy controls. Dogs with heart failure then were randomized to receive either fish oil or placebo for 8 weeks. All parameters were measured again at the end of the study period. At baseline, 54% of dogs with heart failure were cachectic and the severity of cachexia correlated with circulating tumor necrosis factor-alpha concentrations (P = .05). Cytokine concentrations at baseline, however, were not significantly increased in dogs with heart failure compared to controls. Baseline plasma arachidonic acid (P = .02), eicosapentaenoic acid (P = .03), and docosahexaenoic acid (P = .004) concentrations were lower in dogs with heart failure than in controls. Fish oil supplementation decreased interleukin-1 beta (IL-1) concentrations (P = .02) and improved cachexia (P = .01) compared to the placebo group. The mean caloric intake of the heart failure dogs as a group was below the maintenance energy requirement (P < .001), but no difference was found in food intake between the fish oil and placebo groups. Insulinlike growth factor-1 concentrations (P = .01) and reductions in circulating IL-1 concentrations over the study period (P = .02) correlated with survival. These data demonstrate that canine heart failure is associated with cachexia, alterations in fatty acids, and reduced caloric intake. Fish oil supplementation decreased IL-1 concentrations and improved cachexia. In addition, reductions in IL-1 predicted survival, suggesting that anticytokine strategies may benefit patients with heart failure.

The use of enalapril in the treatment of feline hypertrophic cardiomyopathy

The clinical response to enalapril in 19 cats with hypertrophic cardiomyopathy (HCM) was evaluated retrospectively. Eleven cats were in congestive heart failure (CHF) at the time enalapril was prescribed, while only one cat was in CHF when the cats were reexamined three-to-six months later. Significant changes in cardiac dimensions were identified echocardiographically. No adverse effects on blood pressure, serum creatinine, or potassium were noted. Although the preliminary data suggests that enalapril is well tolerated and may contribute to some improvements in cats with HCM, controlled, prospective studies are needed to prove the efficacy of enalapril in this disease.

Magnesium status and the effect of magnesium supplementation in feline hypertrophic cardiomyopathy

Magnesium deficiency has been associated with the development of cardiovascular disease in several species. Cats may be predisposed to alterations in magnesium status because of recent changes in the composition of commercial feline diets. The purposes of this study were 1) to examine the dietary history of cats with hypertrophic cardiomyopathy (HCM), 2) to study magnesium status of cats with HCM compared to normal cats, and 3) to determine the effects of magnesium supplementation in cats with HCM. In part 1 of the study, diets of 65 cats with HCM were examined retrospectively. Forty of the 45 cats for which diets could be determined (89%) ate a diet designed to be magnesium-restricted and/or to produce an acidic urine. In part 2 of the study, 10 cats with HCM were compared to 10 healthy control cats for serum creatinine and magnesium; urine creatinine and magnesium, urine specific gravity and pH, and fractional excretion of magnesium. Urine creatinine and specific gravity were higher in control cats than in cats with HCM. No other differences were found between the 2 groups. In part 3, cats with HCM were supplemented with either 210 mg magnesium chloride (n = 15) or 210 mg lactose (n = 15) for 12 wk. No differences between the 2 groups were found for changes in either magnesium status or echocardiographic parameters. However, the 30 cats with HCM, as a group, did show significant improvements in measures of cardiac hypertrophy over the 12-week period. This was likely the result of treatment with other medications, rather than the magnesium supplementation. The results of this study suggest that cats with HCM are likely to be fed magnesium-restricted diets, but that they do not appear to have altered magnesium status compared to healthy controls.

Idiopathic dilated cardiomyopathy in Dalmatians: nine cases (1990-1995)

OBJECTIVE

To describe the historical, clinical, and echocardiographic findings in Dalmatians with dilated cardiomyopathy (DCM).

DESIGN

Retrospective case series.

SAMPLE POPULATION

9 Dalmatians with a diagnosis of DCM and congestive heart failure (CHF), 9 Doberman Pinschers with DCM and CHF, and 9 dogs of other breeds with DCM and CHF.

PROCEDURE

Disease history; signalment; physical, radiographic, and echocardiographic examination findings; treatment; and outcome from medical records were analyzed.

RESULTS

All Dalmatians were male, with a mean age of 6.8 years. Eight dogs had been fed a commercially available low-protein diet formulated for the prevention of urate uroliths. All dogs had clinical signs consistent with left-sided CHF and had marked left ventricular systolic dysfunction and severe left ventricular dilatation, although arrhythmias were not an important finding in this series of dogs. Median duration of survival was 10 months.

CLINICAL IMPLICATIONS

The DCM syndrome in Dalmatians has some qualities that are distinct from DCM in other breeds of dogs.

Theoretical basis for the use of angiotensin II antagonists in the treatment of heart failure

THERAPEUTIC USE OF ANGIOTENSIN CONVERTING ENZYME (ACE) INHIBITORS: ACE inhibitors are now accepted as valuable therapeutic agents in the management of heart failure. The benefits include symptomatic relief, improvement in left ventricular function, prevention of progressive ventricular dilation, improved survival and decreased incidence of myocardial infarction and unstable angina.

POTENTIAL OF ANGIOTENSIN (ANG) II ANTAGONISTS

Ang II antagonists are expected to produce similar beneficial effects to those of ACE inhibitors, through blockade of vascular, adrenal, renal and prejunctional neuronal Ang II type 1 receptors.

DIFFERENCES BETWEEN ANG II ANTAGONISTS AND ACE INHIBITORS

Despite similarities between ACE inhibitors and Ang II inhibitors with respect to the mechanism of action, there are theoretical differences which may be of clinical importance. Adverse effects seen with ACE inhibitors that are attributed to non-renin-angiotensin system effects (notably angioedema and cough) may be less frequent in patients treated with an Ang II antagonist. ACE inhibitors act within the renin-angiotensin system to prevent the conversion of Ang I to Ang II. Recently, however, enzymes have been described which are capable of producing Ang II via metabolic pathways independent of the classical renin-angiotensin system route.

CONCLUSIONS

At the tissue level, Ang II may still be generated in a patient receiving systemic ACE inhibitor therapy. Ang II blockade at the receptor level may thus be more efficient than ACE inhibition in blocking the undesirable cardiovascular actions of Ang II.

Belt loop gastropexy in the management of gastroesophageal intussusception in a pup

Gastroesophageal intussusception and megaesophagus were diagnosed in a 5-week-old German Shepherd Dog. Exploratory surgery was performed, and belt loop gastropexy was used to maintain proper gastric position after manual reduction of the intussusception. The pup survived surgery and was clinically normal when it was 6 months old. Follow-up contrast radiography revealed resolution of the megaesophagus and apparent permanent gastropexy. Previous reports have indicated extremely high mortality for gastroesophageal intussusception, and resolution of megaesophagus in the dog is unusual.

Primary left ventricular hemangiosarcoma diagnosed by endomyocardial biopsy in a dog

An 8-year-old spayed Golden Retriever was examined because of recent onset of congestive heart failure complicated by ventricular arrhythmias. Echocardiography revealed a thickened, hypokinetic region of the left ventricular free wall. Fluoroscopically guided transarterial endomyocardial biopsy of the hypokinetic region of the left ventricle revealed infiltration of the endocradium by neoplastic cells consistent with hemangiosarcoma. The dog's clinical condition deteriorated 7 weeks later, and necropsy confirmed the diagnosis and primary site of origin of the tumor. This report describes the clinical use of an endomyocardial biopsy technique to diagnose an infiltrating myocardial tumor that was associated with signs mimicking canine dilated cardiomyopathy.

Metaproterenol intoxication in a dog

Intoxication with metaproterenol, a mainly beta-2 selective agonist, was diagnosed in a dog with tachycardia, tachypnea, weakness, vomiting, and a history of exposure to the drug. Electrocardiography and echocardiography disclosed sinus tachycardia with episodes of ventricular tachycardia and exuberant systolic ventricular function, respectively. Administration of the beta blocking drugs propranolol and atenolol led to resolution of the clinical signs. Excessive sympathetic stimulation caused by metaproterenol is an unusual intoxication in dogs.

Effects of calcium channel blockers on coronary vasoconstriction induced by endothelin-1 in closed chest pigs

The purpose of this study was to determine the effects of endothelin-1 on the coronary vascular bed of closed chest pigs. Endothelin-1 (3 to 30 pmol/kg body weight) was selectively administered into the left anterior descending coronary artery. Coronary blood flow and epicardial vessel diameter were measured by quantitative arteriography. Arterial pressure increased after a 30 pmol/kg dose and heart rate was not changed. Coronary blood flow and vessel diameter of the left anterior descending artery significantly decreased by 74% and 32%, respectively (p less than 0.01 versus control) after the 30 pmol/kg dose, whereas these variables modestly decreased in the left circumflex artery. Endothelin-1 in doses of 10 to 30 pmol/kg produced electrocardiographic ST segment elevation associated with decreased oxygen saturation of coronary sinus venous blood. Endothelin-induced coronary vasoconstriction was significantly inhibited after treatment with intravenous diltiazem (0.2 mg/kg, n = 6) or nifedipine (0.1 mg/kg, n = 5), but not after vehicle administration (n = 4). This study demonstrates that intracoronary administration of endothelin-1 causes significant myocardial ischemia through coronary vasoconstriction, which is inhibited by a calcium channel blocker. The data suggest that calcium influx into the smooth muscle cells appears to be involved at least in part in the mechanism of endothelin-induced coronary vasoconstriction in vivo.

Endomyocardial biopsy in cats

A technique for transvenous endomyocardial biopsy of the right ventricle was developed and evaluated for safety and efficacy in anesthetized healthy cats positioned in left lateral recumbency. At least 6 endomyocardial biopsy specimens were obtained from the right ventricle or interventricular septum of 11 cats. In 4 cats, the right jugular vein was torn during attempts to pass the introducing catheter into the right ventricle; however, in only 1 cat did this preclude catheter passage. This cat's heart was biopsied via the left jugular vein. Except for damage to the jugular vein, complications were infrequent, and the biopsy procedure was well tolerated by all cats.

Modified transvenous endomyocardial biopsy technique in dogs

A technique for transvenous endomyocardial biopsy of the right ventricle was developed and evaluated for safety and efficacy in healthy dogs and dogs with dilated cardiomyopathy positioned in lateral recumbency. This technique allowed acquisition of multiple biopsy specimens from the right ventricle of each of 22 hemodynamically normal dogs and 40 of 42 dogs with congestive heart failure. In 2 dogs with dilated cardiomyopathy, transvenous access to the right ventricle could not be achieved, but left ventricular biopsy was performed without complication. Complications were infrequent, and dogs recovered to at least their baseline status within 48 hours. Evaluation of the efficacy and complication rate of the procedure with each of the 2 biopsy instruments currently available identified no differences between them.

Efficacy of digoxin for treatment of cats with dilated cardiomyopathy

The role of digoxin in treatment of cats with dilated cardiomyopathy and other forms of myocardial failure is unclear. We evaluated the chronotropic and inotropic effects of digoxin by comparing baseline, noninvasive indices of cardiac performance with those obtained after 9 +/- 1.3 (mean +/- SEM) days of digoxin treatment in 6 cats with heart failure attributable to dilated cardiomyopathy. Two-dimensionally directed, M-mode echocardiography and electrocardiography were used to determine left ventricular shortening fraction, preejection period (PEP), ejection time (LVET), PEP to LVET ratio, velocity of circumferential fiber shortening, electromechanical systole, heart rate, and PR interval. Treatment consisted of administration of furosemide (mean dosage, 2.4 mg/kg of body weight/day), digoxin in tablet form (approximately 0.01 mg/kg, q 48 h), aspirin (80 mg, q 48 h), and a commercial low-salt diet. In addition, 2 cats were administered short-term, low-dose fluids IV, and 2 were given taurine supplementation at rates of 500 and 1,000 mg/day. Other off-loading or inotropic agents were not administered. Therapeutic or toxic serum digoxin concentration was achieved in all cats. Significant (P less than 0.05) improvement was detected in mean values for shortening fraction, PEP, PEP to LVET ratio, and velocity of circumferential fiber shortening. Mean electromechanical systole and LVET did not change significantly. Improvement, as assessed by indices of cardiac function, was documented in 4 of the 6 cats treated with digoxin, including the 2 cats given taurine supplementation. In the cats given taurine, positive inotropic effect was observed prior to the time when taurine-induced improvement in ventricular function is detectable.(ABSTRACT TRUNCATED AT 250 WORDS)

Lisinopril dose-response relationship in essential hypertension

1. This was a multicentre, double-blind, parallel study in 216 patients with mild to moderate (supine diastolic blood pressure = 95-115 mm Hg) essential hypertension. 2. After a 4-week placebo washout, patients were randomized to placebo or lisinopril 1.25, 5.20 or 80 mg once daily for 6 consecutive weeks. Supine and erect blood pressure was measured 24 h postdose at the end of weeks -2, 0, 2, 4, and 6. 3. There was a linear dose-response relationship for both supine and erect blood pressure. Diastolic blood pressure reductions in the lisinopril 20 and 80 mg day-1 groups were significantly greater than in the placebo or lisinopril 1.25 and 5 mg day-1 groups. 4. Lisinopril, at doses up to 80 mg day-1, was well tolerated.

Effects of compensated heart failure on digoxin pharmacokinetics in cats

To evaluate the effects of compensated heart failure (HF) on digoxin pharmacokinetic properties in cats, 6 cats with dilated cardiomyopathy were compared with 6 clinically normal (control) cats. Digoxin tablets were administered at a dosage of 0.01 mg/kg of body weight, q 48 h for approximately 10 days, until presumed steady state was reached. Both groups were treated concomitantly with aspirin, furosemide, and a commercial low-salt diet. Retrospectively, control and HF cats were calculated to be at 95% and 97% steady state, respectively. At the time blood samples were collected, HF cats were clinically compensated. Serum digoxin concentration [( DXN]) was determined by radioimmunoassay on samples drawn immediately before and 1, 2, 4, 8, 12, 24, 34, and 48 hours after digoxin administration. Measured and calculated values (peak, 8-hour, and mean [DXN]; elimination half-life [t1/2]; oral clearance; and hours during which [DXN] was in the toxic range) were not significantly different between control and HF cats. To predict individual propensity for digoxin intoxication, serum creatinine and urea concentrations and sulfobromophthalein dye retention were measured in control and HF cats prior to the onset of treatment with digoxin. There was no statistically significant correlation between serum creatinine and urea concentrations when compared with sulfobromophthalein dye retention nor between any of these values and digoxin peak, 8-hour, and mean concentrations or t1/2, oral clearance, or hours during which [DXN] was in the toxic range. Mean serum creatinine and urea nitrogen concentrations were significantly greater (P less than 0.01) and sulfobromophthalein dye retention approached significant prolongation (P less than 0.06) in HF cats, compared with that in control cats.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic effects of lisinopril after long-term administration in congestive heart failure

To determine whether acute effects of the angiotensin converting enzyme inhibitor lisinopril are maintained during long-term therapy, 19 patients were studied using right-sided heart catheterization before an initial randomized dose of lisinopril and again after 12 weeks of maintenance lisinopril therapy. During initial evaluation, lisinopril produced significant decreases in mean systemic arterial pressure, pulmonary artery wedge pressure, systemic vascular resistance, mean pulmonary arterial pressure, mean right atrial pressure and pulmonary vascular resistance, and concomitant increases in cardiac index and stroke volume index. After 12 weeks of therapy with lisinopril, the dosage of which was titrated to produce optimal relief of symptoms of congestive heart failure (CHF), repeat hemodynamic studies revealed persistent significant reductions in baseline systemic arterial pressure, pulmonary artery wedge pressure, mean pulmonary arterial pressure and systemic vascular resistance. However, the increases in cardiac index and stroke volume index were not statistically significant. To determine if further acute hemodynamic changes occur during long-term therapy, the patients were readministered a dose of lisinopril. This caused further decreases in systemic arterial pressure, mean pulmonary arterial pressure, pulmonary artery wedge pressure, systemic vascular resistance and mean right atrial pressure, and an increase in cardiac index. Lisinopril did not change stroke work index at either initial or rechallenge study. This study indicates that in patients with CHF treated with lisinopril, acute hemodynamic effects persist after 12 weeks of therapy, and acute hemodynamic response continues to occur upon drug readministration.

Tolerability of long term therapy with enalapril maleate in patients resistant to other therapies and intolerant to captopril

Patients with severe hypertension and/or congestive heart failure (n = 281) who were unresponsive to other therapies and intolerant to captopril received enalapril treatment (mean dose 19.5 mg/day) under study conditions as part of a Compassionate Use Program. Many of these patients had serious concurrent disorders known to predispose them to a greater risk of adverse experiences and death. The mean duration of enalapril treatment was 29 weeks, with a range of 1 day to approximately 3.5 years. Enalapril was generally well tolerated, and the estimated long term probability of patients terminating enalapril therapy because of adverse effects was low. 20 patients had discontinued captopril treatment because of low white blood cell counts; during subsequent enalapril treatment these reactions resolved in 14 patients, persisted in 2 patients, and could not be evaluated in 4 patients. Captopril-related proteinuria improved or resolved in 9 and persisted in 2 of 15 patients, taste disturbances resolved in 35 and persisted in 2 of 38 patients; and rash resolved in all but 7 of 178 patients during enalapril treatment. 18 patients (6%) discontinued enalapril treatment because of lack of efficacy; 6 of these 18 patients died due to a progression of heart failure, and another 11 patients died for other reasons. The deaths were considered unrelated to therapy with enalapril. Adverse reactions were the reason for discontinuation of enalapril treatment in 53 patients (19%). The most common adverse experiences that resulted in discontinuation of enalapril were: impairment of renal function (5%), hypotension (2%) and rash (2%). No neutropenia, proteinuria, or new taste disturbances were recorded as reasons for discontinuation.(ABSTRACT TRUNCATED AT 250 WORDS)

Tolerability of enalapril in congestive heart failure

This report reviews the tolerability profile of enalapril, an angiotensin-converting enzyme (ACE) inhibitor, in the treatment of patients with congestive heart failure. Data have been collected from 546 patients treated with enalapril for up to 9 months in clinical trials other than the Cooperative North Scandinavian Enalapril Survival Study. Results in patients treated with enalapril (n = 193) or placebo (n = 195) in double-blind, controlled clinical trials show that the incidences of death, serious adverse experiences, and adverse experiences requiring discontinuation of double-blind therapy, as well as the overall incidence of such experiences, were similar in the 2 groups. However, certain adverse experiences that are related to the mechanism of action of ACE inhibitors were seen more often after enalapril than after placebo treatment. Dizziness and hypotension were the most frequent adverse experiences reported in patients with heart failure treated with enalapril. The most frequent laboratory adverse experiences were increases in blood urea nitrogen and serum creatinine levels. hyperkalemia was also seen in patients receiving enalapril. It is possible to identify patients at risk of these experiences before initiating treatment with enalapril and to take certain measures (such as withholding or reducing the dose of diuretic drugs and discontinuing potassium supplements or potassium-sparing diuretic drugs) to reduce the likelihood that hypotension, increases in blood urea nitrogen and serum creatinine levels, or hyperkalemia will occur. Angioedema, a recognized adverse effect of ACE inhibitors, was not seen in the clinical trials reviewed here. Cough , another recognized adverse effect of these agents, was seen infrequently and rarely resulted in the discontinuation of enalapril.(ABSTRACT TRUNCATED AT 250 WORDS)