Obesity is widely recognized as the most prevalent nutritional disease in dogs, for which the reported incidence is 21.4% to 28.0%.1-3 Research studies4-6 have revealed a variety of deleterious effects of obesity in dogs, including increased incidence of orthopedic disease, shortened lifespan, and risk of death as a result of pancreatitis. Dogs of all breeds can become obese, but there is the clinical impression that some breeds are at higher risk, including Retriever breeds.
Obesity is also common in humans, and the incidence has risen dramatically over the past 20 years.7 Obesity increases the risk of death from all causes, is linked to increased risk of development of hypertension and type 2 diabetes mellitus,7 and negatively impacts cardiovascular8,9 and pulmonary functions.10-12 Specifically, obesity in people results in decreased FRC, increased Raw, decreased lung compliance, and hypoxemia at rest.13 Additionally, obstructive sleep apnea occurs more frequently with obesity because obesity is associated with increased pharyngeal fat deposits that cause airflow limitation during sleep.14
To our knowledge, the specific effects of obesity on the respiratory system in dogs have not been described, although it has been reported3.a that weight loss is associated with improved respiratory function in obese dogs. Further insight into the effects of obesity on pulmonary mechanics and gas exchange is needed and may provide an impetus for weight loss. The purpose of the study reported here was to evaluate the effects of obesity on pulmonary function in healthy adult dogs. Our hypothesis was that obesity in Retriever breeds causes mechanical dysfunction of the airways and, in particular, that obesity results in increased Raw during both inspiration and expiration in the absence of ventilatory limitations or hypoxemia.
Functional residual capacity
Body condition score
Specific airway resistance
Peak inspiratory flow
Peak expiratory flow
Diffusion capacity of lungs for carbon monoxide
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TRD 5700, Buxco Electronics, Wilmington, NC.
Max 2270, Buxco Electronics, Wilmington, NC.
6023E, National Instruments, Austin, Tex.
XA Biosystem, version 2.9, Buxco Electronics, Wilmington, NC.
Fleisch No. 3, OEM, Lenoir, NC.
Max 2215, Buxco Electronics, Wilmington, NC.
Nova Biomedical, Waltham, Mass.
SPSS, version 11.5, SPSS Inc, Chicago, Ill.
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Bedenice D, Bar-Yishay E, Ingenito EP, et al. Evaluation of headout constant volume body plethysmography for measurement of specific airway resistance in conscious, sedated sheep. Am J Vet Res 2004;65:1259–1264.
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Amis TC, Jones HA. Measurement of functional residual capacity and pulmonary carbon monoxide uptake in conscious Greyhounds. Am J Vet Res 1984;45:1447–1450.
De Lorenzo A, Maiolo C, Mohamed EI, et al. Body composition analysis and changes in airways function in obese adults after hypocaloric diet. Chest 2001;119:1409–1415.
Lutchen KR, Jensen A, Atileh H, et al. Airway constriction pattern is a central component of asthma severity: the role of deep inspirations. Am J Respir Crit Care Med 2001;164:207–215.
Sagawa MM, Nakadoma F, Honjoh T, et al. Correlation between plasma leptin concentration and body fat content in dogs. Am J Vet Res 2002;63:7–10.
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