INVESTIGATIONS INTO HYPERLIPIDEMIA AND ITS POSSIBLE ...

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Hypertriglyceridemia is a relatively common clinicopathologic finding in dogs.
In a study of 1,022 blood samples from both healthy and diseased dogs of various
breeds, 5.4% had an increased serum triglyceride concentration, but the study did not
include grossly lipemic samples. 36
Postprandial hypertriglyceridemia is normal, and
typically resolves within 7-12 hours after a meal, depending on the fat content of the
meal. 14,37 Persistent fasting hypertriglyceridemia is abnormal and can be either primary
(most commonly idiopathic) or secondary to other diseases or drug administration. 37
Overview of canine lipoproteins and lipoprotein metabolism
Canine lipoproteins can be divided into 4 major classes based on their hydrated
density after ultracentrifugation: chylomicrons, very low density lipoproteins (VLDL),
LDL, and HDL. 23,32,38 In humans, a class of intermediate density lipoproteins (IDL) and
lipoprotein (a) have also been identified. These 2 classes of lipoproteins have not been
described in dogs. 39,40 In addition, the existence of several other lipoprotein subclasses
has been recently proposed for humans (LDL-1 through LDL-5, HDL-2a, HDL-2b, and
HDL-3a through HDL-3b), but these subclasses have not been described in dogs to date.
Canine chylomicrons consist of triglycerides, phospholipids, free and esterified
cholesterol, and apo B 48 . 34,37,39-41 Human chylomicrons also contain apo A-I and apo A-
IV, but this has not been reported in dogs. 34,37,39-41 Human and canine VLDL molecules
are formed by endogenously synthesized triglycerides, cholesterol, phospholipids, and
apo B 100 , while canine VLDL molecules also contain B 48 . 39-41 LDL molecules in humans
contain mainly cholesteryl esters and B 100 , but in dogs they also contain B 48 . 37