Cholesterol in Dogs: What Your Dog's Number Actually Means

You see "CHOL: 412 mg/dL" on your dog's bloodwork and the reference range says 130–300. The instinct is to think heart disease — but in dogs, elevated cholesterol almost never means what it means in humans. Dogs don't develop atherosclerosis from high cholesterol. What it does mean is that something else is driving lipid metabolism off course, and that something is usually identifiable and treatable.

Normal Cholesterol Range in Dogs

Most laboratories report a reference range of 130–300 mg/dL for dogs, though exact cutoffs vary by lab. The sample should ideally be fasted for 12 hours — a postprandial (non-fasted) draw can cause a transient mild elevation that normalizes once fat is cleared from the blood. If your dog's panel was drawn without fasting and cholesterol is only mildly elevated, a repeat fasted sample is a reasonable first step.

What High Cholesterol Means in Dogs

Elevated cholesterol (hypercholesterolemia) in dogs is almost always secondary — meaning it's a symptom of another condition, not a standalone disease. The four most common culprits:

Hypothyroidism

This is the most common cause of high cholesterol in dogs. The thyroid hormone T4 regulates lipid metabolism; when T4 is low, cholesterol clearance slows and levels rise. Roughly 80–90% of hypothyroid dogs have elevated cholesterol. If your dog's panel shows high cholesterol alongside lethargy, weight gain, cold intolerance, or skin changes, a T4 test is the first step. Treating hypothyroidism with levothyroxine typically normalizes cholesterol within 4–8 weeks.

Hyperadrenocorticism (Cushing's Disease)

Excess cortisol — whether from a pituitary tumor, adrenal tumor, or long-term steroid medication — disrupts fat metabolism at multiple steps. Cushing's dogs typically show elevated cholesterol alongside elevated ALP, elevated glucose, and dilute urine. The cholesterol elevation here is usually moderate (300–600 mg/dL range).

Diabetes Mellitus

Insulin deficiency impairs the enzyme lipoprotein lipase, which normally clears lipids from the blood. Diabetic dogs often have both high cholesterol and dramatically elevated triglycerides. The lipemia from very high triglycerides (>1,000 mg/dL) can give blood serum a milky appearance and interfere with other lab values like amylase, lipase, and bilirubin.

Protein-Losing Nephropathy (PLN)

When the kidneys leak albumin into urine, the liver compensates by increasing lipoprotein production — driving up both cholesterol and triglycerides. This pattern (high cholesterol + low albumin + high urine protein-to-creatinine ratio) points directly to kidney protein loss.

Miniature Schnauzer Primary Hyperlipidemia

Miniature Schnauzers are genetically predisposed to primary idiopathic hyperlipidemia — elevated triglycerides and cholesterol without an underlying endocrine disease. This is the one case in dogs where dietary management (low-fat diet, sometimes omega-3 supplementation) is the primary treatment rather than treating an underlying condition. If your Miniature Schnauzer has recurrent pancreatitis alongside consistently high lipids, this breed-specific condition is worth discussing with your vet.

What Low Cholesterol Means in Dogs

Low cholesterol (hypocholesterolemia) is less common but clinically significant. It most often indicates:

• • Severe liver disease: The liver synthesizes cholesterol. When hepatic function is severely compromised, cholesterol production drops. Low cholesterol alongside low albumin, low BUN, and elevated bile acids strongly suggests hepatic insufficiency.
• • Protein-losing enteropathy (PLE): Severe intestinal protein loss can reduce cholesterol as part of a generalized hypoproteinemia picture.
• • Hypoadrenocorticism (Addison's disease): Addison's can occasionally produce low cholesterol due to altered cortisol-lipid interactions, though this is not the primary finding.
• • Portosystemic shunt: Dogs with liver shunts often have low cholesterol, small red blood cells (microcytosis), and elevated bile acids.

Which Tests Come Next

High cholesterol on its own is not a diagnosis — it's a pointer. Depending on your dog's other values and symptoms, the next steps typically include:

• • T4 (total thyroxine): Rules in or out hypothyroidism — the most common cause
• • Urine protein:creatinine ratio (UPC): Screens for PLN
• • Fasting triglycerides: Quantifies the lipemia risk and pancreatitis concern
• • Low-dose dexamethasone suppression test or ACTH stimulation: For Cushing's when clinical signs support it
• • Fasting glucose or fructosamine: For diabetes