Echocardiographic Evidence of Left Ventricular Hypertrophy in Obese Dogs

Insights into the interplay between gut microbiota and lipid metabolism in the obesity management of canines and felines

Obesity is a prevalent chronic disease that has significant negative impacts on humans and our companion animals, including dogs and cats. Obesity occurs with multiple comorbidities, such as diabetes, hypertension, heart disease and osteoarthritis in dogs and cats. A direct link between lipid metabolism dysregulation and obesity-associated diseases has been implicated. However, the understanding of such pathophysiology in companion animals is limited. This review aims to address the role of lipid metabolism in various metabolic disorders associated with obesity, emphasizing the involvement of the gut microbiota. Furthermore, we also discuss the management of obesity, including approaches like nutritional interventions, thus providing novel insights into obesity prevention and treatment for canines and felines.

Anaesthetic mortality in dogs: A worldwide analysis and risk assessment

BACKGROUND

Ensuring patient safety during small animal anaesthesia is crucial. This study aimed to assess anaesthetic-related deaths in dogs globally, identify risks and protective factors and inform clinical practice.

METHODS

This prospective cohort multicentric study involved 55,022 dogs from 405 veterinary centres across various countries. Data on anaesthesia-related deaths from premedication to 48 hours post-extubation were collected. Logistic regression was used to analyse patient demographics, American Society of Anesthesiologists (ASA) classification, procedure type and anaesthetic drugs used.

RESULTS

Anaesthetic-related mortality was 0.69%. Most deaths occurred postoperatively (81%). Age, obesity and a higher ASA classification score were associated with increased mortality. Urgent procedures, non-urgent but unscheduled anaesthesias and short procedures also had higher mortality. Some sedatives, systemic analgesics, hypnotics and the use of locoregional anaesthesia were linked to a decrease in mortality.

LIMITATIONS

The limitations of the study include the non-randomised sample, potential selection bias, lack of response rate quantification, variable data quality control, subjectivity in classifying causes of death and limited analysis of variables.

CONCLUSION

Careful patient evaluation, drug selection and monitoring can be associated with reduced mortality. These findings can be used to develop guidelines and strategies to improve patient safety and outcomes. Further research is needed to refine protocols, enhance data quality systems and explore additional risk mitigation measures.

The effect of obesity and subsequent weight reduction on cardiac morphology and function in cats

BACKGROUND

In people, obesity is a risk factor for cardiovascular disease, associated with systemic hypertension, cardiac remodelling and systolic and diastolic dysfunction. Weight reduction can reverse myocardial remodelling and reduce risk of subsequent cardiovascular disease. In cats, far less is known regarding the effects of obesity and subsequent weight reduction on cardiovascular morphology and function. This prospective study aimed to assess cardiac morphology and function, heart rate variability, cardiac biomarkers and body composition before and after controlled weight reduction in cats with obesity. Body composition analysis (by dual energy x-ray absorptiometry, DEXA) and cardiovascular assessment (echocardiography, systemic arterial systolic blood pressure, electrocardiography, plasma cardiac biomarkers) were performed prior to weight management in twenty cats with obesity. These investigations were repeated in eleven cats that reached target weight.

RESULTS

At baseline, systemic hypertension was not documented, but the majority of cats with obesity (15 out of 19) showed echocardiographic evidence of diastolic dysfunction. Eleven of 20 cats had increased maximal end-diastolic septal or left ventricular free wall thickness (≥ 6.0 mm) at baseline. Median (interquartile range) percentage of weight lost in the cats reaching target weight was 26% (17-29%), with a median reduction in body fat mass of 45% (26-64%). Both the end-diastolic left ventricular free wall (median magnitude of change -0.85 mm, IQR -0.05 mm to -1.55 mm, P = 0.019; median percentage reduction 14.0%) and end-diastolic interventricular septum (median magnitude of change -0.5 mm, IQR -0.2 mm to -1.225 mm, P = 0.047; median percentage reduction 7.9%) thickness decreased after weight reduction. Following weight reduction, pulsed wave tissue Doppler imaging of the left ventricular free wall was consistent with improved diastolic function in 4 out of 8 cats, however there was no significant difference in overall diastolic function class. Further, there was no change in heart rate variability or cardiac biomarkers with weight reduction.

CONCLUSION

An increase in left ventricular wall thickness and diastolic dysfunction were common echocardiographic features in cats with obesity within our study and may be reversible with successful weight and fat mass loss. Further studies are required to clarify the clinical consequences of these findings.

Obesity, inflammation, and cancer in dogs: Review and perspectives

Obesity is the most common nutritional disease in dogs, and its prevalence has increased in recent decades. Several countries have demonstrated a prevalence of obesity in dogs similar to that observed in humans. Chronic low-grade inflammation is a prominent basis used to explain how obesity results in numerous negative health consequences. This is well known and understood, and recent studies have pointed to the association between obesity and predisposition to specific types of cancers and their complications. Such elucidations are important because, like obesity, the prevalence of cancer in dogs has increased in recent decades, establishing cancer as a significant cause of death for these animals. In the same way, intensive advances in technology in the field of human and veterinary medicine (which even proposes the use of animal models) have optimized existing therapeutic methods, led to the development of innovative treatments, and shortened the time to diagnosis of cancer. Despite the great challenges, this review aims to highlight the evidence obtained to date on the association between obesity, inflammation, and cancer in dogs, and the possible pathophysiological mechanisms that link obesity and carcinogenesis. The potential to control cancer in animals using existing knowledge is also presented.

The effect of obesity and subsequent weight reduction on cardiac structure and function in dogs

Background

In people, the cardiovascular effects of obesity include systemic hypertension, cardiac remodelling and both systolic and diastolic dysfunction, whilst weight reduction can reverse myocardial remodelling and reduce risk of subsequent cardiovascular disease. To date, variable results are reported in studies of the effect of obesity and controlled weight reduction on cardiovascular morphology and function in dogs. This prospective study aimed to assess cardiac function, heart rate variability, cardiac biomarkers and body composition before and after weight reduction in pet dogs with obesity. Twenty-four client-owned dogs referred for weight management due to obesity were recruited. To assess the cardiac effects of obesity, body composition analysis (by dual energy X-ray absorptiometry, DEXA) and cardiovascular assessment (echocardiography, Doppler blood pressure, electrocardiography, cardiac biomarkers) were performed prior to weight management. Twelve dogs completed the study and reached target weight, receiving a further cardiovascular assessment and DEXA. A Wilcoxon-signed rank test was used to compare each variable pre- and post- weight reduction.

Results

Median (interquartile range) duration of weight loss was 224 days (124–245 days), percentage weight loss was 23% (18–31%) of starting weight. Median change in body fat mass was -50% (-44% to -55%; P = 0.004), whilst median change in lean mass was -7% (+ 1% to -18%, P = 0.083).

Before weight reduction, diastolic dysfunction (evidence of impaired relaxation in all dogs), increased left ventricular wall thickness and mildly elevated systolic blood pressure (14/24 ≥ 160 mmHg, median 165 mmHg (140–183)) were common features in dogs with obesity. However, systolic left ventricular wall dimensions were the only variables that changed after weight reduction, with a decrease in both the systolic interventricular septum (P = 0.029) and systolic left ventricular free wall (P = 0.017). There was no evidence of decreased heart rate variability in dogs with obesity (P = 0.367), and no change in cardiac biomarker concentrations with weight reduction (N-terminal proBNP, P = 0.262; cardiac troponin I P = 0.657).

Conclusions

Canine obesity results in diastolic dysfunction and left ventricular hypertrophy, the latter of which improves with significant weight and fat mass reduction. Further studies are required to clarify the clinical consequences of these findings.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03449-4.

Mild to moderate overweight in dogs: is there an impact on routine hematological and biochemical profiles, echocardiographic parameters and cardiac autonomic modulation?

Obesity is considered the most common nutritional disease of dogs. Even though overt obesity is more likely to impair health, even moderately overweight dogs are at greater risk for requiring medication for chronic health problems earlier in life. Although the number of overweight dogs far exceeds the number of obese ones, most of the studies published so far focused on derangements in a mixed overweight/obese population (Body condition score - BCS ≥7/9) rather than in separated groups. This study aimed to evaluate the impact of mild to moderate obesity on routine hematological and biochemical profile and cardiovascular parameters in dogs. Nine healthy lean (BCS =4-5/9) and 24 overweight dogs (BCS = 6-7/9) were enrolled. Complete blood count, serum biochemistry analyses, echocardiographic parameters, and cardiac autonomic function by heart rate variability (HRV) were determined. In our study population, although total protein, globulin and phosphorus concentrations were increased in overweight compared to lean dogs, all complete blood count and biochemical parameters were within reference ranges for both groups. Parameters usually increased in obese dogs, like triglycerides and cholesterol concentrations, were within reference ranges in our overweight population. There were no significant changes in echocardiographic parameters, but HRV had a significant decrease in high frequency (HF) power (P = 0.02), suggesting a depression in parasympathetic activity. Our findings show that mild to moderate overweight dogs do not show the hematological and echocardiographic alterations already reported for mixed overweight/obese populations but might have impaired cardiac autonomic modulation. Although not enough to make conclusions, our data raise the question of whether research studies should place overweight and obese dogs in the same category.

Identification and Characterization of Circulating MicroRNAs as Novel Biomarkers in Dogs With Heart Diseases

Background: Previous studies in humans have confirmed dysregulations of circulating microRNAs (miRNAs) in patients with various cardiovascular diseases. However, studies on circulating miRNAs in dogs with various heart diseases are limited in number. This study aimed to identify significantly dysregulated circulating miRNAs and characterize them as novel biomarkers in dogs with heart diseases. Materials and Methods: Circulating levels of 11 miRNAs were investigated in serum samples of 82 dogs (72 with heart diseases and 10 healthy dogs) using quantitative reverse transcription-polymerase chain reaction. The results were correlated to clinical data including echocardiographic results and N-terminal pro B-type natriuretic peptide (NT-proBNP) levels. Results: Upregulation of cfa-miR-130b was observed in dogs with myxomatous mitral valve degeneration (MMVD) stage B, patent ductus arteriosus, and pulmonic stenosis. In dogs with MMVD stage B, cfa-miR-130b was upregulated and correlated with clinical indices. In receiver operating characteristic (ROC) analysis, cfa-miR-130b accurately distinguished dogs with diseases from healthy dogs. We also observed that cfa-miR-375 and cfa-let-7b were upregulated in dogs with concentric cardiac hypertrophy. The cfa-miR-375 was correlated with concentric hypertrophy indices and was an accurate indicator of concentric hypertrophy in ROC analysis. Conclusions: The miRNAs identified in this study may be used as novel biomarkers and possible candidates for therapeutic targets in various canine heart diseases.

Biologics and their delivery systems: Trends in myocardial infarction

Cardiovascular disease is the leading cause of death around the world, in which myocardial infarction (MI) is a precipitating event. However, current therapies do not adequately address the multiple dysregulated systems following MI. Consequently, recent studies have developed novel biologic delivery systems to more effectively address these maladies. This review utilizes a scientometric summary of the recent literature to identify trends among biologic delivery systems designed to treat MI. Emphasis is placed on sustained or targeted release of biologics (e.g. growth factors, nucleic acids, stem cells, chemokines) from common delivery systems (e.g. microparticles, nanocarriers, injectable hydrogels, implantable patches). We also evaluate biologic delivery system trends in the entire regenerative medicine field to identify emerging approaches that may translate to the treatment of MI. Future developments include immune system targeting through soluble factor or chemokine delivery, and the development of advanced delivery systems that facilitate the synergistic delivery of biologics.

Obesity-Induced Heart Rate Variability Impairment and Decreased Systolic Function in Obese Male Dogs

Simple Summary

Obesity in dogs can induce many adverse health effects including musculoskeletal problems, respiratory distress, metabolic syndrome, and cardiovascular diseases. In humans with obesity, heart rate variability (HRV) is used to identify and predict the risk of cardiovascular diseases. However, this predictive tool has never been used in veterinary medicine, and the relationship between obesity and HRV has rarely been investigated. In this study, we investigated HRV, plasma oxidative stress (MDA), and cardiac function in obese male dogs. We hypothesized that obese male dogs have decreased cardiac function and impaired HRV compared to non-obese dogs. Our study found that obese dogs have decreased cardiac systolic function and impaired HRV, as indicated by reduced percentages of cardiac contraction and impaired cardiac autonomic activity compared to non-obese dogs. We concluded that obesity can decrease systolic function and cause HRV impairment, which might increase the risk of cardiovascular disease in dogs. In addition, HRV might be used as a predictive or prognostic tool in the prevention of cardiovascular disease in obese dogs.

Abstract

Obesity can induce cardiovascular diseases in both humans and animals. Heart rate variability (HRV) is an indicator of sympathovagal balance and is used to identify cardiovascular diseases in humans. However, HRV and cardiac function have rarely been investigated in obese dogs. This study investigated the effect of obesity on oxidative stress, HRV, and cardiac function in obese and non-obese dogs. The nine-scale body condition score (BCS) system was used to determine obesity. Thirty small breed dogs were divided into a normal weight group (n = 15) and an obese group (n = 15). All dogs underwent physical examination, plasma malondialdehyde (MDA) measurement, electrocardiography, echocardiography, and two hours of Holter monitoring. This study found that obese dogs had increased plasma MDA and sympathovagal imbalance, which was indicated by impaired time and frequency domains compared to normal weight dogs. Although cardiac function was within normal limits, the echocardiographic study found that the obese dogs had reduced cardiac wall thickness and lower systolic function, as indicated by a reduction in %ejection fraction, %fractional shortening, increased left ventricular (LV) internal diameter during systole, and LV end-systolic volume compared to normal weight dogs. This study concluded that obesity in dogs can induce increased plasma oxidative stress, impaired HRV, and reduced cardiac systolic function compared to non-obese dogs.

Effect of a Weight Loss Program on Biochemical and Immunological Profile, Serum Leptin Levels, and Cardiovascular Parameters in Obese Dogs

This study aimed to investigate the effects of a weight loss program (WLP) on biochemical and immunological profile, and cardiovascular parameters in a cohort of dogs with naturally occurring obesity. Eleven obese dogs [body condition scoring (BCS), ≥7/9] were enrolled into the study and underwent clinical and cardiovascular examination, and blood testing before (T0) and after 6 months (T1) of WLP. Eleven normal weight (BCS, 4/5) healthy dogs were used as a control (CTR) group. Compared to the CTR group, at T0 obese dogs expressed higher serum leptin concentrations (p < 0.0005) that significantly decreased after weight loss (p < 0.005) but remained higher than the CTR group. Furthermore, obese dogs showed considerably lower levels (p < 0.0005) of regulatory T cell (Treg) compared to the CTR group, but they did not change after weight loss at T1. In obese dogs, tumor necrosis factor (TNF)-α and interleukin (IL)-6 concentrations were substantially reduced at T1 (p < 0.0001 and p < 0.005). Regarding the cardiovascular parameters, only one obese dog was hypertensive at T0, and systolic blood pressure values showed no significant differences at the end of the WLP. The ratio of interventricular septal thickness in diastole to left ventricle internal diameter in diastole (IVSd/LVIDd) was significantly greater in obese dogs at T0 than in the CTR group (p < 0.005). It decreased after weight loss (p < 0.05). In obese dogs, troponin I level significantly reduced with weight loss (p < 0.05), while endothelin-1 level did not differ statistically. The results suggest that the immune dysregulation in the presence of high leptin levels and reduced number of Treg could affect obese dogs as well as humans. Based on our findings, we may speculate that a more complete immune-regulation restore could be obtained by a greater reduction in fat mass and a longer-term WLP. Finally, left ventricular remodeling may occur in some obese dogs. However, in canine species, further studies are needed to investigate the impact of obesity and related WLP on cardiovascular system.

Leptin and Immunological Profile in Obesity and Its Associated Diseases in Dogs

Growing scientific evidence has unveiled increased incidences of obesity in domestic animals and its influence on a plethora of associated disorders. Leptin, an adipokine regulating body fat mass, represents a key molecule in obesity, able to modulate immune responses and foster chronic inflammatory response in peripheral tissues. High levels of cytokines and inflammatory markers suggest an association between inflammatory state and obesity in dogs, highlighting the parallelism with humans. Canine obesity is a relevant disease always accompanied with several health conditions such as inflammation, immune-dysregulation, insulin resistance, pancreatitis, orthopaedic disorders, cardiovascular disease, and neoplasia. However, leptin involvement in many disease processes in veterinary medicine is poorly understood. Moreover, hyperleptinemia as well as leptin resistance occur with cardiac dysfunction as a consequence of altered cardiac mitochondrial metabolism in obese dogs. Similarly, leptin dysregulation seems to be involved in the pancreatitis pathophysiology. This review aims to examine literature concerning leptin and immunological status in obese dogs, in particular for the aspects related to obesity-associated diseases.

Changes of cardiac function in diabetic dogs

OBJECTIVE

This study aimed to evaluate cardiac function and compare the concentration of cardiac biomarkers including cardiac troponin I (cTnI), galectin-3 (Gal-3), and N-terminal pro B-type natriuretic peptides (NT-proBNP) in diabetic and control dogs.

ANIMALS

Thirty-nine dogs were included. The diabetic and control groups consisted of 19 and 20 dogs, respectively.

METHODS

Plasma cTnI, Gal-3, and NT-proBNP concentrations were measured in the diabetic and control groups. Echocardiography was performed in all dogs to evaluate cardiac structure and function. Echocardiographic values and cardiac biomarker concentrations between the two groups were compared with the Mann-Whitney U test. The p-value < 0.05 was considered statistical significance.

RESULTS

No evidence of cardiac structural changes was detected in diabetic dogs on two-dimensional echocardiography. The echocardiographic values of diabetic and control dogs were within reference intervals. Echocardiographic changes indicating diastolic dysfunction assessed by spectral flow Doppler echocardiography and tissue Doppler imaging were found in diabetic dogs (42.10%) compared with control dogs (10.00%; p = 0.022). Diabetic dogs with durations of diabetes mellitus > 1 year had an increased left ventricular wall thickness and echocardiographic changes suggesting diastolic dysfunction compared with those with duration of diabetes mellitus < 1 year. No evidence of systolic dysfunction was detected in diabetic dogs. No significant difference in plasma cTnI, Gal-3, and NT-proBNP concentrations was found between the two groups.

CONCLUSIONS

Echocardiographic changes suggested that left ventricular diastolic dysfunction was detected in diabetic dogs without changes in the concentration of cardiac biomarkers including cTnI, Gal-3, and NT-proBNP compared with the age- and breed-matched control dogs.

Sonographic Evaluation of Liver Hemodynamic Indices in Overweight and Obese Dogs

Background

Hepatic circulatory disturbances have been associated with obesity and fatty liver in humans. In the veterinary literature, however, there is limited information regarding the effects of different body condition scores (BCS) on liver hemodynamic indices in dogs.

Objectives

To investigate the influence of BCS on liver hemodynamic indices.

Animals

Fifty‐three client‐owned dogs of various breeds were included.

Methods

Prospective observational study. Dogs were divided into 3 BCS groups using a 5‐point scale: G1 – 12 ideal dogs, G2 – 21 overweight dogs, G3 – 20 obese dogs. Mean portal velocity (MPV), portal blood flow volume (PBFV), portal congestion index (PCI), hepatic artery resistivity index (HARI), and hepatic vein (HV) spectral wave were obtained by pulsed Doppler sonography. Alkaline phosphatase (ALP), gamma‐glutamyl transferase (GGT), and alanine aminotransferase (ALT) activities were determined. Liver enzymes activities and liver hemodynamic indices were compared among groups.

Results

Obese dogs had lower MPV, higher percentage of abnormal hepatic vein spectral wave and higher median ALP activity than did ideal dogs (P < 0.05). Overweight and obese dogs had lower PBFV than ideal dogs (P < 0.01). Overweight dogs had higher median GGT activity than ideal dogs (P < 0.05). No difference was observed for PCI, HARI and median ALT activity among the groups.

Conclusions and Clinical Importance

Obesity was associated with changes in portal vein indices and in HV spectral wave. These changes were accompanied by significant differences in some liver enzymes activities and could be a sign of early liver disease.

Cardiac and Metabolic Variables in Obese Dogs

Background

The etiology of obesity‐related cardiac dysfunction (ORCD) is linked to metabolic syndrome in people. Studies have indicated that obese dogs have components of metabolic syndrome, warranting evaluation for ORCD in obese dogs.

Objectives

To evaluate cardiac structure and function and metabolic variables in obese dogs compared to ideal weight dogs.

Animals

Forty‐six healthy, small‐breed (<25 pounds), obese dogs (n = 29) compared to ideal weight dogs (n = 17).

Methods

A cross‐sectional study of cardiac structure and function by standard and strain echocardiographic measurements and quantification of serum metabolic variables (insulin:glucose ratios, lipid analysis, adiponectin, inflammatory markers).

Results

Compared to the ideal weight controls, obese dogs had cardiac changes characterized by an increased interventricular septal width in diastole to left ventricular internal dimension in diastole ratio, decreased ratios of peak early to peak late left ventricular inflow velocities, and ratios of peak early to peak late mitral annular tissue velocities, and increased fractional shortening and ejection fraction percentages. The left ventricular posterior wall width in diastole to left ventricular internal dimension in diastole ratios were not significantly different between groups. Systolic blood pressure was not significantly different between groups. Obese dogs had metabolic derangements characterized by increased insulin:glucose ratios, dyslipidemias with increased cholesterol, triglyceride, and high‐density lipoprotein concentrations, decreased adiponectin concentrations, and increased concentrations of interleukin 8 and keratinocyte‐derived chemokine‐like inflammatory cytokines.

Conclusions and Clinical Importance

Compared to ideal weight controls, obese dogs have alterations in cardiac structure and function as well as insulin resistance, dyslipidemia, hypoadiponectinemia, and increased concentrations of inflammatory markers. These findings warrant additional studies to investigate inflammation, dyslipidemia, and possibly systemic hypertension as potential contributing factors for altered cardiac function.

Blood Pressure, Serum Glucose, Cholesterol, and Triglycerides in Dogs with Different Body Scores

The objective of this research was to determine the frequency for the occurrence of MS in dogs, using the criteria determined, and to correlate the criteria of dogs that would characterize the MS with different body condition score (BCS). 271 dogs with different body scores were studied, with 101 dogs with BCS 4-5; 101 dogs with BCS 6-7; and 69 dogs with BCS 8-9. Among the dogs studied, 62 (22,87%) had two or more inclusion criteria for MS. Of these, 28 had BCS 6-7, while 34 dogs had BCS 8-9. Therefore, 27,72% of overweight dogs had inclusion criteria for MS and 49,27% of obese ones had two or more inclusion criteria for MS. When only overweight and obese dogs were considered as a total population, it was observed that 36,47% got inclusion criteria for the MS. No dog with BCS 4-5 showed two or more inclusion criteria for MS. The metabolic syndrome, according to the parameters for inclusion defined in the literature, was observed in 22,87% of the animals studied and in 36% of dogs overweight or obese. Furthermore, MS was most common in obese (49%) compared to overweight dogs (27%).

Asymmetric left ventricular hypertrophy associated with morbid obesity mimicking familial hypertrophic cardiomyopathy

Asymmetric septal hypertrophy with systolic anterior motion of the mitral valve is frequently a phenotypic, but not pathognomonic, expression of genetic hypertrophic cardiomyopathy (HCM) with or without obstruction. It can, however, be associated nonspecifically with other forms of increased left ventricular (LV) afterload. We herein report the case of a young man with obesity cardiomyopathy and heart failure who presented with asymmetric septal hypertrophy and marked LV hypertrophy, and endomyocardial biopsy ruled out genetic HCM.

Obesity-hypertension and its relation to other diseases in dogs

Obesity is a chronic disease in which adipose tissue accumulates in such a way that it affects the health of the patient and is associated with a myriad of alterations such as systemic hypertension (HTN). The mechanisms by which obesity causes HTN are complex and involve several organic mechanisms. The objective of this study was to determine the correlation between obesity to HTN in dogs in accordance with recent international protocols (systolic blood pressure >160 mmHg) relating to age, genre, gonadal status, breed and other diseases commonly associated with HTN. A total of 244 dogs were studied, 105 non-obese controls and 139 in the obese group. For both groups, healthy and a variety of diseased dogs were observed; the correlations between pathologies and obesity were studied, paying special attention to diseases whose pathophysiologies could lead to HTN. We conclude that obesity is not a risk factor for dogs to develop HTN, and that HTN present in these patients was related to comorbidities such as chronic kidney disease, cardiopathies and endocrinopathies.

Effect of body weight loss on cardiopulmonary function assessed by 6-minute walk test and arterial blood gas analysis in obese dogs

BACKGROUND

Few studies show the detrimental effect of canine obesity on cardiopulmonary function (CPF). The 6-Minute Walk Test (6MWT) is a noninvasive exercise test easy to perform in clinical settings.

OBJECTIVE

The aim of this study was to investigate the effect of obesity and body weight loss (BWL) on CPF assessed by the 6MWT and arterial blood gas analysis.

ANIMALS

Six experimental Beagles and 9 privately owned obese dogs were enrolled in a diet-induced BWL program.

METHODS

Arterial blood gas analysis and 6MWT were repeated in obese subjects (BCS 8-9/9), in the middle of BWL (overweight, BCS 6-7/9), and in lean dogs (BCS 5/9). Heart rate (HRp) and oxygen saturation (SpO2 ) were measured by pulse oximetry before the 6MWT, at midtest, and during a 5-minute recovery period.

RESULTS

Twelve dogs completed the BWL program (initial BW, 27.3 ± 2.9 kg; final BW, 20.85 ± 2.9, lsmeans ± SE, P ≤ .001). BWL caused a significant increase in 6MWT walked distance (WD; obese: 509 ± 35 m; overweight: 575 ± 36 m; lean: 589 ± 36 m; P ≤ .05). Resting arterial blood gas results were not influenced by BWL. Including all time points, obese dogs showed higher HRp and lower SpO2 compared to overweight and lean dogs. SpO2 at the end of the walk was significantly lower in obese dogs.

CONCLUSION AND CLINICAL IMPORTANCE

Obesity negatively affects 6MWT performances in dogs. The 6MWT may be used to demonstrate the efficacy of BWL to improve CPF and quality of life in obese dogs. Although BWL induced significant improvement of cardiopulmonary parameters before ideal BW, WD improved until the end of the BWL program.