Indices for M-mode measurements in dogs usually have been based on the assumption that a linear relationship exists between these measurements and body weight (BW) or body surface area (BSA). The relationships between the geometry of 3-dimensional objects do not support this assumption. The purposes of this study were to retrospectively examine M-mode data from a large number of dogs of varying sizes and breeds that were examined by a large number of ultrasonographers, to use the allometric equation to determine the appropriate BW exponent required to predict these cardiac dimensions, and to determine normal mean values and prediction intervals for common M-mode variables. Linear regression analyses of data from 494 dogs (2.2-95 kg) revealed a good correlation between M-mode measurements and BW after logarithmic transformation of the data (r 2 .55-.88). Most variables were most closely related to an index of body length, BW 1/3 , although the exponent that best predicted diastolic and systolic left ventricular wall thicknesses was closer to 0.25. No variable indexed well to BW or BSA. With these data, appropriate mean values and prediction intervals were calculated for normal dogs, allowing veterinarians to correctly and appropriately index M-mode values. The equations developed from this study appear to be applicable to adult dogs of most breeds.

Indices for M-mode measurements in dogs usually have been based on the assumption that a linear relationship exists between these measurements and body weight (BW) or body surface area (BSA). The relationships between the geometry of 3-dimensional objects do not support this assumption. The purposes of this study were to retrospectively examine M-mode data from a large number of dogs of varying sizes and breeds that were examined by a large number of ultrasonographers, to use the allometric equation to determine the appropriate BW exponent required to predict these cardiac dimensions, and to determine normal mean values and prediction intervals for common M-mode variables. Linear regression analyses of data from 494 dogs (2.2-95 kg) revealed a good correlation between M-mode measurements and BW after logarithmic transformation of the data (r 2 ϭ .55-.88). Most variables were most closely related to an index of body length, BW 1/3 , although the exponent that best predicted diastolic and systolic left ventricular wall thicknesses was closer to 0.25. No variable indexed well to BW or BSA. With these data, appropriate mean values and prediction intervals were calculated for normal dogs, allowing veterinarians to correctly and appropriately index M-mode values. The equations developed from this study appear to be applicable to adult dogs of most breeds.Key words: Canine; Echocardiography; Heart; Reference range. M-mode echocardiography is commonly used to measure linear cardiac dimensions of cardiac chambers, walls, and great vessels. Because adult dogs range in weight from Ͻ2 to Ͼ90 kg, any definition of normal heart size must take into account the variation caused by differences in body size. Consequently, it is important to identify equations that accurately describe the relationships between body size and cardiac dimensions. Several authors have published equations, nomograms, or tables that are intended to be used as reference ranges for M-mode measurements for adult dogs of varying size and breed. [1][2][3][4][5][6][7][8][9][10][11] Critics have questioned the usefulness of some of these reference ranges because of small sample sizes, lack of data points for the extremes of body size, wide prediction intervals, and the use of inappropriate statistical methods. 5,[10][11][12][13][14][15] In addition, many authors have assumed that a linear relationship exists between linear cardiac dimensions and either body weight (BW) or body surface area (BSA), which might not be true. Evidence also has been presented suggesting that a general equation might never be accurate because breed is a factor Davis, CA 95616-8747; e-mail: cccornell@ucdavis.edu. Submitted March 7, 2003; Revised July 1 and October 31, 2003; Accepted December 11, 2003. Copyright that can cause M-mode measurements in dogs of the same weight to differ. 13The statistical methods used to produce the previously mentioned reference ranges were not described in every case, but in 2 studies in which the authors detailed their methods, reference ranges we...

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BackgroundHypertrophic cardiomyopathy is the most prevalent heart disorder in cats and principal cause of cardiovascular morbidity and mortality. Yet, the impact of preclinical disease is unresolved.Hypothesis/ObjectivesObservational study to characterize cardiovascular morbidity and survival in cats with preclinical nonobstructive (HCM) and obstructive (HOCM) hypertrophic cardiomyopathy and in apparently healthy cats (AH).AnimalsOne thousand seven hundred and thirty client‐owned cats (430 preclinical HCM; 578 preclinical HOCM; 722 AH).MethodsRetrospective multicenter, longitudinal, cohort study. Cats from 21 countries were followed through medical record review and owner or referring veterinarian interviews. Data were analyzed to compare long‐term outcomes, incidence, and risk for congestive heart failure (CHF), arterial thromboembolism (ATE), and cardiovascular death.ResultsDuring the study period, CHF, ATE, or both occurred in 30.5% and cardiovascular death in 27.9% of 1008 HCM/HOCM cats. Risk assessed at 1, 5, and 10 years after study entry was 7.0%/3.5%, 19.9%/9.7%, and 23.9%/11.3% for CHF/ATE, and 6.7%, 22.8%, and 28.3% for cardiovascular death, respectively. There were no statistically significant differences between HOCM compared with HCM for cardiovascular morbidity or mortality, time from diagnosis to development of morbidity, or cardiovascular survival. Cats that developed cardiovascular morbidity had short survival (mean ± standard deviation, 1.3 ± 1.7 years). Overall, prolonged longevity was recorded in a minority of preclinical HCM/HOCM cats with 10% reaching 9‐15 years.Conclusions and Clinical ImportancePreclinical HCM/HOCM is a global health problem of cats that carries substantial risk for CHF, ATE, and cardiovascular death. This finding underscores the need to identify therapies and monitoring strategies that decrease morbidity and mortality.

The prevalence of cardiomyopathy in Irish wolfhounds was evaluated by retrospective review of the results of cardiovascular examinations carried out in 500 dogs presented for veterinary services at the author's practice. Abnormalities were found in 209 (41.8%) of the dogs examined. Dilated cardiomyopathy (DCM) was diagnosed in 121 (24.2%) of the dogs and was accompanied by atrial fibrillation in 106 dogs. Seventeen dogs were suffering from advanced congestive heart failure (CHF), and 55 dogs were suffering from mild to moderate CHF as a result of DCM. Congestive heart failure was most commonly characterized by mild to severe pleural effusion due to right-sided heart failure in addition to pulmonary edema. Rhythm disturbances without evidence of DCM were detected in 48 dogs. Forty dogs had echocardiographic abnormalities without signs of DCM. Soft to moderate mitral regurgitations were diagnosed in 13 (2.6%) of these 40 dogs examined. In 39 dogs that died as a result of DCM, the median survival time from the time of diagnosis was 5.1 months, and in 59 dogs with DCM that are still alive, the median survival time is 15.7 months.