Triglycerides in cats and dogs

What it shows

Fat from food enters the blood in large particles called chylomicrons; the liver also releases triglycerides in particles called VLDL. An enzyme on the walls of blood vessels, lipoprotein lipase, clears these particles so tissues can use or store the fat. Triglycerides go up when more fat arrives, as after a meal, or when clearance slows — for example with diabetes, cortisol excess, steroid medicines or an inherited problem with that enzyme.

The rise after eating is real and fast. In a study of 100 healthy dogs cited by eClinPath, triglycerides increased in 92 of them between 2 and 8 hours after a meal, peaking at about 2 hours. VCA notes they are often raised for 6–12 hours after a meal, especially a high-fat one. A lot of triglyceride makes serum look milky; this is called lipemia.

Higher than reference — what it may be a sign of

• A recent meal: eClinPath calls blood taken after eating the most common cause of milky serum in dogs and cats — a collection artefact rather than disease.
• Diabetes mellitus: lipemia in diabetic dogs and cats is due to markedly high triglycerides.
• Hyperadrenocorticism (Cushing’s syndrome) and steroid medicines: corticosteroids reduce lipoprotein lipase activity and can cause high fasting triglycerides in dogs and cats.
• Pancreatitis: mainly triglycerides, with a mild rise in cholesterol.
• Hypothyroidism and some kidney diseases: VCA lists them with diabetes, Cushing’s disease and pancreatitis among conditions behind hyperlipidemia.
• Inherited forms: Miniature Schnauzers (seen in dogs older than about four years); VCA also names Shetland Sheepdogs, Beagles and Collies. In cats an inherited defect of lipoprotein lipase is described.

Lower than reference

eClinPath states that low triglyceride concentrations are not of diagnostic relevance. A value below the range is noted and read together with the rest of the panel; on its own it is not a cause for concern.

Look at together with

• Cholesterol — both high fit a metabolic or breed-related lipid disorder; high cholesterol alone points to other causes.
• Glucose and fructosamine — to check for diabetes.
• Pancreatic lipase — Merck considers severe hypertriglyceridemia (generally 500 mg/dL or more) a risk factor for pancreatitis in dogs, though not in cats.
• Other results from a milky sample — eClinPath lists sodium, potassium and chloride as falsely decreased in lipemic samples, and glucose, ALT, AST, CK, calcium, phosphate, urea and others as possibly affected in either direction. If triglycerides are very high, ask the vet which numbers on the form to rely on.

Units and conversion

European labs usually report triglycerides in mmol/L, North American labs in mg/dL. 1 mg/dL is about 0.0113 mmol/L (eClinPath rounds it to 0.011), so 100 mg/dL is about 1.1 mmol/L. In the app each row keeps the unit printed on the form; the chart converts to one unit so forms from different labs line up.

Reference range

The reference range is on your lab’s form. It assumes a fasted sample: VCA notes that if the pet ate within the previous 12 hours, the vet will likely repeat the test after a 12- or 18-hour fast. A high value from a non-fasted sample is therefore a reason to recheck, not a conclusion. If the fasted value stays high, the vet looks for the underlying cause. VCA mentions that extremely high triglycerides can, uncommonly, lead to seizures and that lipids can deposit in the eye.

Cats and dogs

Sources

1. eClinPath (Cornell University College of Veterinary Medicine) — Triglycerides
2. eClinPath (Cornell University College of Veterinary Medicine) — Lipid overview
3. eClinPath (Cornell University College of Veterinary Medicine) — Interference indices
4. VCA Animal Hospitals — Hyperlipidemia
5. Steiner JM. Pancreatitis in Dogs and Cats. Merck Veterinary Manual