Clarke E. Atkins

Guidelines for the Identification, Evaluation, and Management of Systemic Hypertension in Dogs and Cats

Consensus Statements of the American College of Veterinary Internal Medicine (ACVIM) provide veterinarians with guidelines regarding the pathophysiology, diagnosis, or treatment of animal diseases. The foundation of the Consensus Statement is evidence-based medicine, but if such evidence is conflicting or lacking, the panel provides interpretive recommendations on the basis of their collective expertise. The Consensus Statement is intended to be a guide for veterinarians, but it is not a statement of standard of care or a substitute for clinical judgment. Topics of statements and panel members to draft the statements are selected by the Board of Regents with input from the general membership. A draft prepared and input from Diplomates is solicited at the ACVIM Forum and via the ACVIM Web site and incorporated in a final version. This Consensus Statement was approved by the Board of Regents of the ACVIM before publication.

Prospective clinical evaluation of an ELISA B-type natriuretic peptide assay in the diagnosis of congestive heart failure in dogs presenting with cough or dyspnea

BACKGROUND B-type natriuretic peptide (BNP) is increased in dogs with congestive heart failure (CHF). HYPOTHESIS The purpose of this study was to evaluate the clinical utility of a novel canine-specific enzyme-linked immunosorbent assay of BNP for the diagnosis of CHF in dogs presenting with either cough or dyspnea. ANIMALS Three hundred and thirty dogs from 2 large university teaching hospitals. METHODS We prospectively measured plasma BNP concentrations in 3 groups of dogs: (1) normal adult dogs (n = 75), (2) dogs with asymptomatic heart disease (n = 76), and (3) dogs with cough or dyspnea (n = 179). The final diagnosis of dogs with cough or dyspnea and the severity of CHF (International Small Animal Cardiac Health Council Heart Failure Classification [ISACHC]) were determined by medical record review by a study cardiologist who was blinded to the results of the BNP assay. RESULTS Dogs with CHF had a higher median BNP concentration (24.6 pg/mL) than dogs with noncardiac causes of cough or dyspnea (2.6 pg/mL) (P < .0001). The area under the curve was 0.91 for the receiver operating curve analysis of the diagnostic accuracy of the BNP measurement to differentiate CHF from other causes of cough or dyspnea. The median BNP concentrations in dogs were 3.0 pg/mL with ISACHC I, 17.8 pg/mL with ISACHC II, and 30.5 pg/mL with ISACHC III. (P < .0001) CONCLUSION AND CLINICAL IMPORTANCE Measurement of BNP is useful in establishing or in excluding the diagnosis of CHF in dogs with cough or dyspnea. B-type natriuretic peptide concentrations rose significantly as a function of severity of CHF.

Multicenter Evaluation of Plasma N-Terminal Probrain Natriuretic Peptide (NT-pro BNP) as a Biochemical Screening Test for Asymptomatic (occult) Cardiomyopathy in Cats

BACKGROUND B-type natriuretic peptide concentrations reliably distinguish between cardiac and respiratory causes of dyspnea, but its utility to detect asymptomatic cats with occult cardiomyopathy (OCM) is unresolved. HYPOTHESIS/OBJECTIVES Determine whether plasma N terminal probrain natriuretic peptide (NT-proBNP) concentration can discriminate asymptomatic cats with OCM from normal cats, and whether NT-proBNP concentration correlates with clinical, biochemical, and echocardiographic parameters. ANIMALS One hundred and fourteen normal, healthy cats; 113 OCM cats. METHODS Prospective, multicenter, case-controlled study. NT-proBNP was prospectively measured and cardiac status was determined from history, physical examination, and M-mode/2D/Doppler echocardiography. Optimal cut-off values were derived using receiver operating characteristic (ROC) curve analysis. RESULTS NT-proBNP was higher (median, interquartile range [25th and 75th percentiles]) in (1) OCM (186 pmol/L; 79, 478 pmol/L) versus normal (24 pmol/L; 24, 32 pmol/L) (P < .001); and (2) hypertrophic obstructive cardiomyopathy (396 pmol/L; 205, 685 pmol/L) versus hypertrophic cardiomyopathy (112 pmol/L; 48, 318 pmol/L) (P < .001). In OCM, NT-proBNP correlated (1) positively with LVPWd (ρ = 0.23; P = .01), LA/Ao ratio (ρ = 0.31; P < .001), LVs (ρ = 0.33; P < .001), and troponin-I (ρ = 0.64; P < .001), and (2) negatively with %FS (ρ = -0.27; P = .004). Area under ROC curve was 0.92; >46 pmol/L cut-off distinguished normal from OCM (91.2% specificity, 85.8% sensitivity); >99 pmol/L cut-off was 100% specific, 70.8% sensitive. CONCLUSIONS AND CLINICAL IMPORTANCE Plasma NT-proBNP concentration reliably discriminated normal from OCM cats, and was associated with several echocardiographic markers of disease severity. Further studies are needed to assess test performance in unselected, general feline populations, and evaluate relationships between NT-proBNP concentrations and disease progression.

Understanding Feline Heartworm Infection: Disease, Diagnosis, and Treatment

Feline heartworm disease is a very different clinical entity from canine heartworm disease. In cats, the arrival and death of immature heartworms in the pulmonary arteries can cause coughing and dyspnea as early as 3 months postinfection. Adult heartworms suppress the function of pulmonary intravascular macrophages and thus reduce clinical disease in chronic feline heartworm infection. Approximately 80% of asymptomatic cats self-cure. Median survival time for symptomatic cats is 1.5 years, or 4 years if only cats living beyond the day of presentation are considered. Aberrant worm migration is more frequent than it is in dogs, and sudden death can occur with no prior clinical signs. The bacterial endosymbiont Wolbachia likely contributes to the inflammatory pathology of heartworm disease, but its role is not yet fully clear. Unfortunately, the diagnosis, treatment, and management of feline heartworm disease are far from simple. Antemortem diagnosis is hampered by low worm burdens, the frequency of all-male infections, and nonspecific radiographic lesions. It is up to the veterinarian to determine the correct index of suspicion and choose the right combination of diagnostic tests to achieve an answer. Treatment is symptomatic because adulticide therapy is risky and does not increase survival time. Despite the dangers of feline heartworm disease, less than 5% of cats in the United States are on chemoprophylaxis. It is important for veterinarians to take a proactive preventive stance because heartworm infection in cats is a multisystemic disease that has no easy cure.

Association of Dilated Cardiomyopathy with the Striatin Mutation Genotype in Boxer Dogs

BACKGROUND Myocardial disease in the Boxer dog is characterized by 1 of 2 clinical presentations, dilated cardiomyopathy (DCM) characterized by ventricular systolic dysfunction, dilatation and tachyarrhythmias, and arrhythmogenic right ventricular cardiomyopathy (ARVC) characterized by ventricular tachyarrhythmias, syncope, and sudden death. Boxer ARVC has been associated with a deletion in the striatin gene in some families. HYPOTHESIS/OBJECTIVES We hypothesized that both presentations represent a single disease, and the development of DCM in the Boxer is associated with the striatin deletion. ANIMALS Thirty-three adult Boxer dogs with DCM, 29 adult Boxer dogs with the striatin deletion and ARVC, and 16 Boxers without cardiac disease. METHODS DNA samples were evaluated for the striatin deletion. Association of the deletion with the DCM phenotype was tested by a Fishers exact test. T-tests were used to evaluate potential differences between the positive heterozygous and positive homozygous groups with DCM with regard to age, LVIDD, LVIDS, and FS%. RESULTS Thirty of 33 dogs with DCM were positive for the striatin deletion. The striatin mutation and the homozygous genotype were strongly associated with the DCM phenotype (P < .001 and P = .005). There was no statistical difference between the heterozygous and homozygous groups with regard to age and echocardiographic measurements. CONCLUSIONS AND CLINICAL IMPORTANCE This study demonstrates an association between DCM in the Boxer dog and the striatin mutation, particularly with the homozygous genotype. The observation that 3/33 dogs developed DCM and lacked the striatin mutation suggests that there is at least 1 other cause of DCM in the Boxer dog.

Pharmacologic management of myxomatous mitral valve disease in dogs

Myxomatous mitral valve disease (MMVD) causing mitral regurgitation is the most important disease of the heart in small animal cardiovascular medicine. Because MMVD is an example of a chronic disease that progresses from mild to severe over years, treatment strategies change with the stage of the disease. In this review the treatment options are compared and contrasted as they are discussed relative to the recently published ACVIM consensus statement regarding the treatment of MMVD. Results from clinical trials and evidence-based medicine are likely to provide significant improvements in the management of MMVD in the coming decades.

Acute effect of pimobendan and furosemide on the circulating renin-angiotensin-aldosterone system in healthy dogs.

BACKGROUND The renin-angiotensin-aldosterone system (RAAS) is activated in states of decreased cardiac output and by certain cardiovascular therapeutic agents, such as loop diuretics and vasodilators. HYPOTHESIS Short-term treatment with the inodilator, pimobendan, will not activate the circulating RAAS because its vasodilatory action will be offset by its positive inotropic property, thereby ameliorating RAAS stimulation at the juxtaglomerular apparatus. Furthermore, pimobendan will suppress RAAS activation produced by furosemide. ANIMALS Nine healthy laboratory dogs were used in this study. METHODS Experimental, cross-over study. Dogs were administered pimobendan (0.5 mg/kg q12h) for 4 days followed by furosemide (2 mg/kg q12h) and then, after a wash-out period, a combination of the drugs. Aldosterone : creatinine (A : Cr) was measured at the end of each treatment cycle. RESULTS There was no significant increase in the average urinary A : Cr with the administration of pimobendan (control urinary A : Cr = 0.46, standard deviation (SD) 0.33; pimobendan A : Cr = 0.48, SD 0.28). There was a significant increase in the average urinary A : Cr after administration of furosemide (urinary A : Cr = 1.3, SD 0.70) and with the combination of furosemide and pimobendan (urinary A : Cr = 2.9, SD 1.6). CONCLUSIONS AND CLINICAL RELEVANCE Short-term administration of high-dose pimobendan, does not activate the RAAS in healthy dogs. Pimobendan did not prevent RAAS activation associated with furosemide therapy. These results in healthy dogs suggest that furosemide therapy, with or without pimobendan, should be accompanied by RAAS suppressive therapy.

The role of noncardiac disease in the development and precipitation of heart failure.

The varying roles of a widely diverse group of noncardiac disorders on the heart, particularly their ability to induce heart failure, are explored. A general overview of the cardiac effects of volume and pressure overloading is followed by specific discussions of the roles of vascular, endocrine and metabolic, renal, gastrointestinal, central nervous system, hematologic, and other miscellaneous disorders (heat stroke, sepsis, immune-mediated disease, obesity, malnutrition, and pregnancy) in producing cardiac dysfunction and failure in companion animals. Pathogenetic and pathophysiologic mechanisms are emphasized.

Evaluation of the effect of pleural effusion on central venous pressure in cats.

This study was undertaken to determine if pleural effusion (PEF) increases central venous pressure (CVP) in cats, to define any relationship between volume of PEF and CVP and to ascertain the significance of CVP alterations in cats having PEF and suspected right heart failure (RHF). CVP was measured from a jugular vein before (CVPpre) and after (CVPpost) bilateral thoracentesis in 9 cats with naturally occurring PEF and under experimental conditions in 3 spontaneously breathing anesthetized cats receiving graded intrathoracic infusion of saline. Volumes of introduced and recovered fluid were recorded. A significant decrease occurred in CVP after thoracentesis in cats with naturally occurring PEF (mean difference, 4.5 cm H2O; range, 0-7.0 cm H2O, P < .005). The magnitude of change in CVP was constant (r = 0.36, P > .05) over the range of volumes recovered (range, 95-450 mL or 16.4-90 mL/kg). Five cats had CVPpre suggestive of RHF (range, 8.16-20.4 cm H2O). After thoracentesis, RHF was ruled out in 1 cat (CVPpost, 4.08 cm H2O) and the CVP declined but remained abnormally high (9.52 cm H2O) in 1 cat with a mediastinal mass. In 2 cats with confirmed RHF (CVPpre, 20.4 and 16.3 cm H2O), CVP decreased after thoracentesis but remained abnormally high (CVPpost, 14.96 and 10.88 cm H2O). In 1 cat with noncardiogenic PEF and inadequate removal of fluid, CVPpost (8.16 cm H2O) did not decrease. Experimentally, a positive linear relationship was observed between CVP and volume of PEF. The threshold volume required to increase CVP (17 mL/kg) approximated that suggested by clinical observation (22 mL/kg). PEF increases CVP and can cause abnormally high CVP in the absence of RHF.

Comparison of Polymerase Chain Reaction with Bacterial 16s Primers to Blood Culture to Identify Bacteremia in Dogs with Suspected Bacterial Endocarditis

BACKGROUND Identification of the bacterial organism in dogs with endocarditis is challenging. Human studies have reported the utility of the polymerase chain reaction (PCR) to amplify and identify bacterial nucleic acid from infected valvular tissue and blood. HYPOTHESIS/OBJECTIVES We hypothesized that PCR using primers designed to amplify the bacterial 16s gene would identify circulating bacteria in dogs with suspected bacterial endocarditis more consistently than standard blood culture techniques. ANIMALS Eighteen dogs with suspected bacterial endocarditis based upon clinical and echocardiographic findings. Fifteen clinically normal dogs served as negative controls. METHODS Prospective study of dogs evaluated for suspect endocarditis at 6 veterinary hospitals. A blood sample was drawn from all dogs and evaluated with both a single-sample PCR and standard 3-sample blood culture techniques. RESULTS Blood culture identified noncontaminant bacteria in 6/18 study animals (33%) and 1 control dog; PCR identified noncontaminant bacteria in 7/18 study animals (39%). There were no study animals in which the 2 tests identified different bacteria (κ = 1.0). However, bacteria were identified by both techniques in only 2/18 study animals. When results from both PCR and blood culture were considered together, a noncontaminant bacterial organism was identified in 11/18 study animals (61%). CONCLUSION AND CLINICAL IMPORTANCE The results of this study suggest that although single sample PCR with 16s primers was not more sensitive than blood culture for detection of bacteremia in dogs with suspect endocarditis, performing both techniques simultaneously did increase the likelihood of identification of bacteria in blood.