Hyperlipidemia in Dogs

Lipids are naturally occurring, organic fatty compounds that are essential to cell membranes, where they help to store energy and relay intracellular messages. Lipoproteins are complexes made of lipids and proteins and are critical to the transportation of lipids in the plasma. Hyperlipidemia occurs when a disturbance in lipoprotein metabolism causes a disruption in fat transportation to and from tissue. This disturbance can be caused by various conditions, and can often be fixed through treatment that relies heavily on dietary considerations.

Hyperlipidemia is the condition of increased levels of lipids in the blood, which are made up of triglycerides, cholesterol, or both. Used interchangeably with the term hyperlipoproteinemia which refers to increased lipoproteins, this irregularity can be primary, or secondary to other conditions. This overabundance of fat molecules in the body can leave fatty deposits in skin and eye areas, and can lead to more serious conditions, such as nerve paralysis and seizures.

Symptoms can be intermittent, and can include:

• Vomiting
• Diarrhea
• Abdominal discomfort or pain
• Yellow, cholesterol filled skin lesions
• Pancreatitis
• Creamy appearance of blood vessels in the retina of the eyes
• Yellowish plaques near the eyelids
• Yellow or creamy fat deposits in the cornea
• Nerve paralysis
• Behavioral changes
• Anemia
• Seizures

Types 

Generally, hyperlipidemia is divided into two types.

Primary hyperlipidemia – This is when the cause of the condition is seen as genetic or idiopathic, and is less common than secondary hyperlipidemia. This type can be associated with specific breeds.

Secondary hyperlipidemia – This type is caused by some other condition and is more common. Complications can occur with this type, such as pancreatitis, liver disease, and neurologic disease, to name a few.

Postprandial hyperlipidemia is the natural elevation of lipids that occurs after meals, and usually resolves within 7-12 hours after a meal. Testing for primary or secondary hyperlipidemia will take this into account.

Primary hyperlipidemia can be caused by:

• Hypertriglyceridemia, or elevated triglyceride levels; seen most often in Miniature Schnauzers and Brittany Spaniels
• Hypercholesterolemia, or elevated cholesterol levels; seen most often in Briard, Doberman, Rottweiler, Rough-coated Collie, Great Pyrenees, and Shetland Sheepdogs
• Combined hypercholesterolemia and hypertriglyceridemia. Seen most often in Beagles
• Excessive dietary intake of lipids
• Genetic disposition
• Insufficient amounts of hormones that regulate lipid levels

 Secondary hyperlipidemia causes can include:

• Diabetes mellitus
• Cushing’s disease
• Hypothyroidism
• Hyperadrenocorticism
• Nephrotic syndrome
• Cholestasis
• Obesity
• Pancreatitis
• Liver failure
• Lymphoma
• Glycogen storage disease type 1a
• Glucocorticoids
• Chronic Leishmania infections

A diagnosis is based on symptoms, dietary history and test results. A blood sample can determine if hyperlipidemia is present. Blood taken after a 12 hour fast can avoid confusion with postprandial hyperlipidemia. Serum tests are used to look for elevated levels of triglycerides and cholesterol. In cases where hypertriglyceridemia is suspected, a chylomicron test on lipemic samples can discover the form of lipoprotein causing the condition. A heparin release test may also be performed to assess the level of activity of the lipoprotein lipase. If any underlying condition is suspected to be causing the hyperlipidemia, appropriate tests will be given.

Treatment for primary hyperlipidemia is with dietary modification, with or without supportive medications. In cases of secondary hyperlipidemia, the underlying disease is treated in addition to a low fat diet.

Diet

Hyperlipidemia can be controlled with a low fat diet, and can be adjusted to accommodate concurrent diseases, such as obesity and diabetes. Primary hyperlipidemia affected dogs are usually given ultra-low fat diets, which can be homemade or formulated specifically for your dog by a nutritionist. Often a serum triglyceride goal is set, and the specialized diet is fed for 4-8 weeks. Then, blood serum levels are reevaluated and treatment continues based on those findings. Often, this reevaluation is performed every 6-8 weeks of treatment to monitor your dog’s lipid levels. If lipid levels do not drop enough, medication is often added.

Medications and supplements

When diet is not enough, lipid lowering drugs can be prescribed. These include fibrates, such as gemfibrozil, fenofibrate and bezafibrate. Niacin can also be prescribed, but like gemfibrozil, it can have adverse side effects and is used only when the diet fails to maintain triglyceride levels. Statins drugs can lower cholesterol levels, but side effects include liver toxicity. Other lipid lowering drugs are well tolerated, as is Omega fish oils, which may be needed in cases of hyper-VLDL production. Continuous monitoring is needed throughout the treatment process.

Your veterinarian will need to monitor your dog’s lipid levels, both throughout and after treatments. This regular monitoring can help you assess your dog’s recovery and allow adjustments to be made as needed. With proper treatment and a successful diet, your dog’s hyperlipidemia can be controlled.