Chromatographic Analysis of the Lipid Fractions in Obese Dogs and Dogs with Hyperadrenocorticism
Obesity and endogenous hyperadrenocorticism in dogs are common clinical conditions and both present clinical and laboratory similarities, such as weight gain and dyslipidemia. The hyperlipidemic conditions are usually associated to a variety of clinical problems, which include gastrointestinal alterations, hepatic lipidosis, atherosclerosis and metabolic syndrome. The aim of the study was to characterize the lipid profile and lipoprotein fractions in normal dogs (n=10) and compare them with obese dogs (n=10) and dogs with hyperadrenocorticism (n=6), selected from a veterinary hospital environment. The lipoproteins were separated by liquid chromatography in high-resolution gel filtration in the FPLC (fast protein liquid chromatography) system and the plasma concentrations of total cholesterol (TC) and total triglycerides (TG) were measured by enzymatic methods. In the normal group, the TC means and SD were 193±44 mg/dL (percentage distribution of the fractions: VLDL-COL 2.34%, LDL-COL 15.79%, HDL-COL 81.86%); TG values were 50±15 mg/dL (percentage distribution of the fractions: VLDL-TG 39.17%, LDL-TG 35.9%, HDL-TG 24.94%). In the group of obese dogs, TC means and SD were 240±63 mg/dL (VLDL-COL 3.983%, LDL-COL 21.21%, HDL-COL 74.81%) whereas the TG values were 93±52 mg/dL (VLDL-TG 59.79%, LDL-TG 26.62%, HDL-TG 13.68%). In the group of dogs with hyperadrenocorticism the TC means and SD values were 348±105 mg/dL (VLDL-COL 15.11%, LDL-COL 28.63%, HDL-COL 56.26%) whereas TG values were 300±227 mg/dL (VLDL-TG 64.07%, LDL-TG 29.65%, HDL-TG 6.231%). When compared to the normal and obese dogs, the animals with hyperadrenocorticism presented a significant increase (p<0.01) in the total triglycerides and cholesterol levels and a higher distribution in the VLDL-CT fraction. Additionally, the distribution of the HDL-TC and HDL-TG fractions was significantly lower in dogs with hyperadrenocorticism when compared to normal dogs. When compared to the normal dogs, the obese dogs did not show significant alterations, although they presented proportionally higher levels of TC, TG and LDL-TC and LDL-TG as well as lower HDL-TC and HDL-TG levels. It was concluded that, regarding the group of studied animals, the dogs with hyperadrenocorticism present a significant difference when compared to normal and obese dogs in relation to cholesterol and triglyceride metabolism and their VLDL and HDL fractions, which favors the differential diagnosis between these diseases and suggests a higher risk of metabolic and atherosclerotic complications in dogs with hyperadrenocorticism.