High cholesterol in dogs, when discovered in a dog's blood work, can feel alarming for dog owners considering the role elevated cholesterol plays in heart disease in humans. However, in dogs, diseases such as atherosclerosis and coronary artery disease are fortunately not very common and don't occur as a result of a diet rich in fats known to cause clogged arteries as it happens in humans. A dog's body was designed to purposely eat meat and fats, and therefore, diseases stemming from high cholesterol would have been highly maladaptive, potentially leading to dogs not being capable of surviving as a species.
A Disease of Humans
High cholesterol leading to debilitating and potentially life threatening atherosclerosis and coronary artery disease is a disease that is specifically found in humans.
More specifically, atherosclerosis affects only herbivores. As a matter of fact, animals such as cats, lions, tigers and dogs can eat a diet that is saturated with fat and cholesterol and they do not develop plaque building up their arteries.
Interestingly, the only way to cause atherosclerosis in a carnivore animal is to remove the thyroid gland. Upon removal, saturated fat and cholesterol affect carnivore animals in the same fashion as it happens in herbivores, explains Dr. William C. Robert MD. The thyroid gland indeed in dogs is known for producing hormones that help control metabolism and help regulate cholesterol.
Let's face it: dogs are equipped with the body of a carnivore. They have sharp teeth purposely designed for puncturing and tearing meat, their intestinal tract is short (so that they can rapidly digest meat and excrete it) and they are not prone to having the bad cholesterol in their blood as humans do.
This is mostly because their liver has the remarkable capacity to excrete it, rather than allow it to accumulate in their bodies as it happens in humans.
"It is virtually impossible, for example, to produce atherosclerosis in a dog even when 100 grams of cholesterol and 120 grams of butter fat are added to its meat ration. (This amount of cholesterol is approximately 200 times the average amount that human beings in the USA eat each day!)"~William Clifford Roberts MD
High Cholesterol in Dogs
Cholesterol is for a good extent absorbed from the dog's diet (in negligible amounts), but it is also produced by the liver from fatty acids and to a smaller extent by other organs. Once ingested, cholesterol is metabolized by the liver where it is then excreted.
Because how long ago a dog ate may impact the levels of cholesterol detected on bloodwork, it's important for the vet to know whether a dog has fasted or not prior to testing. Postprandial hypercholesterolemia (high cholesterol levels after eating) tends to last for up to 12 hours after eating.
In dogs, a finding of high cholesterol levels in a biochemistry profile has a different significance than it does in humans. Elevated cholesterol in dogs doesn't typically affect the cardiovascular system. Elevated cholesterol in dogs instead may affect their pancreas, eyes, skin and nervous system.
High cholesterol in dogs may lead to a condition known as pancreatitis. When the eyes are affected, changes may occur leading to lipid keratopathy, stromal dystrophy, lipids in the aqueous humor, uveitis, blindness, and lipemia retinalis, explains veterinarian Dr. Deb. Skin changes although uncommon, may lead to itching and hair loss. Issues associated with the nervous system include seizures and behavioral changes.
High cholesterol in dogs is typically HDL high-density lipoprotein– the“good cholesterol” rather than the bad cholesterol (LDL, low density lipoprotein). Generally, normal cholesterol levels in dogs range from around 131 to 345 mg/dL as seen in the reference below. HDL and LDL levels in dogs are not tested in lab work since dogs don't suffer from the same types of cholesterol problems humans do.
" It is possible to induce hypercholesterolemia in the dog by dietary manipulation, but the current existing fat content of commercial dog foods is hard to achieve hypercholesterolemia in dogs with normal lipid metabolism."~ Johnny D. Hoskins
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Causes of High Cholesterol in Dogs
High cholesterol levels in dogs, also known medically as hypercholesterolemia may be nothing to worry about or it can be due to underlying conditions. Generally, high cholesterol in a dog's blood work is concerning when the dog is showing signs of illness and there are other concomitant abnormal laboratory findings.
Hypothyroidism, the production of low levels of thyroid hormone, can play a major role in a dog's cholesterol metabolism and cause elevations. According to board-certified veterinarian Dr. Richard B. Ford, high cholesterol levels is found in 2/3 of hypothyroid dogs. This is because too little thyroid hormones can decrease the level of an enzyme known for dissolving fats and therefore the LDL cholesterol uptake. Affected dogs may develop secondary atherosclerosis in this case, but it is rather uncommon.
Diabetes, a deficiency of insulin, may also play a role in decreasing the levels of a dog's fat-dissolving enzyme. Other conditions known to cause high cholesterol in dogs include another endocrine condition known as Cushing’s disease, (excessive production of the hormone cortisol), acute pancreatitis and metabolic diseases such as kidney disease (protein-losing nephropathies). Liver disease (cholestatic liver disease) may too lead to high cholesterol in dogs, since, if the liver itself is diseased, it may not be able to excrete cholesterol effectively.
The administration of steroids is a known cause for increased levels of cholesterol. This may include topical medications such as steroid -based eye drops or steroid-based sprays, creams or ointments.
In some cases, elevated levels of cholesterol and triglycerides may be due to inherited disorders that affect the metabolism of cholesterol and triglycerides (inherited hypercholesterolemia). Such cases were found only in certain breeds including miniature schnauzers, briards, Rottweilers, cocker spaniels, Shetland sheepdogs, miniature poodles and Dobermans.
When no exact underlying metabolic or endocrine disease is found, elevated cholesterol levels is referred to as being "idiopathic."
Did you know? According to veterinarian Mark C. Johnson the reason why dogs do not develop atherosclerosis is because dogs have no documented detectable activity of cholesteryl ester transfer protein. This ultimately results in higher HDL levels.
Treatment of Elevated Cholesterol in Dogs
Mild elevation of cholesterol in dogs may not be clinically significant and therefore may not typically require any further assessment or treatment.
Because most cases of high cholesterol in dogs are caused by secondary, underlying disorders, addressing them should help resolve the elevation. This means that, once the underlying cause is tackled, the dog’s blood cholesterol and blood triglyceride levels should return to normal levels.
For example, in the case of hypothyroidism, once the dog is prescribed the drug thyroxine (or other similar drug), his cholesterol should go down once the thyroxine levels in the blood are balanced. or in the case of diabetes, excessive cholesterol levels get lower once glycemic control is attained.
In some cases of elevated cholesterol, the vet may prescribe a low-fat, high-fiber diet. Royal Canin offers a low-fat diet. Other low-fat diets may include Hills' R/D, or Hill's W/D, which is a bit higher in fat than R/D, but more palatable. If the case warrants it, veterinarians may prescribe medications as well to lower a dog's high cholesterol.
- We think we are one, we act as if we are one, but we are not one, William Clifford Roberts, MD (Editor in Chief) The American Journal of Cardiology, 1990, vol. 66,896
- Twenty questions on atherosclerosis, William C. Roberts, MD, Proc (Bayl Univ Med Cent). 2000 Apr; 13(2): 139–143.
- DVM360: Monitor serum concentrations of triglyceride or cholesterol for hyperlipidemia, by Johnny D. Hoskins, DVM, PhD, DACVIM
- Hyperlipidemia Disorders in Dogs Mark C. Johnson, DVM, DACVP (Clinical Pathology), Texas A & M University
- Textbook of Veterinary Internal Medicine, 7th Edition. Authors: Stephen Ettinger Edward Feldman.