Cardiomyopathies and congestive heart failure (CHF) pursuant to these cardiomyopathies are relatively common in cats. The presence of cachexia, a complex condition involving both muscle wasting and weight loss, is well known in both people and dogs with CHF. Cachexia can also occur in association with other diseases, such as chronic kidney disease and neoplasia. Cachexia is a disease-related phenomenon, while sarcopenia refers to muscle wasting associated with aging in the absence of intercurrent disease.
The purpose of this retrospective study of the medical records of 125 cats with CHF was to determine if cachexia was also present in cats with CHF and to learn about its potential association with clinical signs, laboratory findings, and survival time in cats with CHF. Prior to beginning the study, the investigators had to determine the criteria for identification of cachexia that they would use in analyzing the records of the feline patients. In humans, at least 11 definitions of cachexia are used. Seven different definitions of cachexia were initially used to identify cardiac cachexia in the cats’ medical records.
Weight loss is one of the criteria commonly used to identify cardiac cachexia in people, but loss of muscle mass is now considered the most important factor in promoting the negative effects of cachexia. Humans in CHF accompanied by muscle loss, with or without weight loss, have more functional deficits and decreased quality of life compared to those who have experienced weight loss only. The investigators’ working hypothesis was that muscle condition scoring was most likely to identify more cats with cardiac cachexia than other criteria.
The seven definitions of cachexia used to evaluate the records of the 125 cats with CHF were as follows:
(1) weight loss of at least 5% in the 12 months following CHF diagnosis and 3 of the following criteria at the time of diagnosis: decreased muscle strength, fatigue, anorexia, low fat-free mass index, or biochemical abnormalities (anemia or hypoalbuminemia);
(2) At least one prescription for appetite stimulation pharmaceuticals such as mirtazapine or cyproheptadine;
(3) 5% or more weight loss after CHF diagnosis:
(4) More than 5% weight loss in the 6 months prior to CHF diagnosis;
(5) Unintended loss of 5% or more of body weight in the 6-12 months prior to CHF diagnosis;
(6) Low body condition score (BCS; <4/9) at the time of CHF diagnosis;
(7) Muscle loss based on muscle condition score (MCS) at the time of CHF diagnosis.
Data for all 125 cats were only available for criteria (6) and (7). Only 15/125 (12.0%) met criterion (6), while 52/125 (41.6%) met criterion (7). Ultimately, given that all 125 cats had MCS available in their records, that muscle is the body compartment most adversely affected in cachexia, and that MCS reflects loss of muscle mass only, unlike criteria (1), (3), (4), (5) and (6), further analysis of the records used MCS only (criterion 7) to categorize cats with or without cachexia.
Study cats diagnosed with CHF ranged in age from 1.2-19.6 years (median age 10.3 years). There were 89 neutered males and 36 spayed females. Most of the cats (n = 101) were domestic shorthair or domestic longhair; the rest represented a variety of breeds. Hypertrophic cardiomyopathy was present in 107 cats; dilated cardiomyopathy in 8, unclassified or restrictive cardiomyopathy in 8, and 2 had arrhythmogenic right ventricular cardiomyopathy.
The cats with cachexia were more likely to have pleural effusion than cats without cachexia. Hematocrit and hemoglobin concentrations in cachectic cats were lower than in non-cachectic cats. Cats with cachexia were older, and had higher BUN concentrations and higher BUN/creatinine ratios, but not higher creatinine. Significantly higher neutrophil concentrations, lower BCS, and lower body weights were also found in the cachectic cats. It is likely that some of the older cats with cachexia had concurrent sarcopenia. Significantly shorter survival times based on all-cause mortality were found in the cats with cachexia based on MCS; however, this only demonstrates association and not causation. Nonetheless, this association should prompt the clinician to identify, and if possible, treat cachexia in cats with CHF.
Although cats with other concurrent diseases that could be associated with muscle loss and decrease in body weight, such as neoplasia, chronic kidney disease, diabetes mellitus or unregulated hyperthyroidism, were excluded from the study, sarcopenia and/or occult disease could have coexisted with cachexia in some of the patients included in the study. In order to further evaluate the prevalence, role and impact of cachexia in cats with CHF, and its potential relationship with echocardiographic findings, the authors recommend that echocardiographic measurements be included in future studies of larger groups of cats with CHF. [PJS]