Hardening and Blockage of the Arteries in Dogs

Atherosclerosis is the medical term for what is commonly called hardening or blockage of the arteries. Deposits of cholesterol, triglycerides and other forms of fat collect in blood vessels and thicken the walls, causing an obstruction or rupture. This deprives an organ of blood and causes it to die. 

The condition is rare in dogs, but it may occur in older male canines. A few breeds appear to be predisposed to it, including Doberman Pinschers, Labrador Retrievers, Poodles, Miniature Schnauzers, Beagles and Shetland Sheepdogs. 

Atherosclerosis results from high cholesterol

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Symptoms of atherosclerosis cover a wide range of systems, and some of them are related to accompanying conditions. Signs can include:

• Lethargy
• Loss of appetite
• Hair loss
• Frequent urination
• Frequent thirst
• Vomiting
• Obesity
• Hind limb weakness (due to Cushing’s Disease)
• Panting
• Weight loss
• Diarrhea
• Voracious appetite
• Seizures
• Collapse
• Signs of loss of blood flow to the extremities, such as ulcers, sores that won’t heal and infections on the feet and legs

Types

• Spontaneous (primary)
• Secondary

Spontaneous atherosclerosis is caused by elevated levels of cholesterol (lipids) in the blood, but is quite rare in canines. Dogs almost always have concurrent chronic conditions that cause or influence this condition, called secondary atherosclerosis.

The body needs cholesterol to perform many vital functions, but when there is too much circulating in the blood, it may be deposited inside the artery walls, building up over time and causing narrowing of the vessels. This causes tissue death in vital organs such as the heart, kidneys, thyroid gland, aorta, spleen, gastrointestinal system, and liver.

High levels of low-density cholesterol and triglycerides can be caused by a number of factors, including:

• High-fat, low-fiber diet
• Lack of exercise
• Diabetes mellitus
• Cushing’s Disease 
• Hypothyroidism 
• Hyperthyroidism 
• High blood pressure 
• Obesity
• Steroid medications
• Pancreatic inflammation
• Pregnancy
• Infections such as Chlamydia

Dogs with concurrent diabetes and hypothyroidism are 50 times more likely to develop atherosclerosis than other dogs. Genetics is thought to be a factor, as well, but further study is needed to make a clear connection.

Diagnosing atherosclerosis begins with a thorough medical history and physical examination. It’s important that all symptoms leading up to the clinic visit be discussed with your veterinarian. Atherosclerosis cannot be diagnosed solely by history and exam, which means that your veterinarian will order other tests as well. Because the condition can impact several systems and be caused by other illnesses, diagnostic testing can be wide-ranging.  

A blood profile will include a complete blood count and blood chemistries. Thyroid and liver panels will be done, along with a urinalysis to detect involvement of the kidneys. X-rays and ultrasound of the heart, liver, and other organs can help determine the extent of the disease and give clues to the organs’ structural and functional status. An electrocardiogram will define electrical activity within the heart that impacts rhythm, rate and function.

An arteriogram, which involves injecting dye into a blood vessel and watching as it circulates through the body, can identify organs that are involved and is performed during a cardiac catheterization procedure under sedation.

Treatment of atherosclerosis is highly individualized and is treated by treating the underlying condition causing it, along with an attempt to lower cholesterol levels in the blood. 

Lower cholesterol

Medications that affect cholesterol levels, including Gemfibrizol, may be given. Gemifibrizol targets triglyceride levels, which is a factor in coronary artery disease. Lifestyle changes such as including a low-fat, high-fiber diet combined with exercise are generally prescribed. If necessary, weight loss is also recommended.

Control diabetes

Control of diabetes is an important treatment goal. There are no effective oral medications to lower blood sugar for dogs, so their blood glucose must be tested daily, followed by insulin injections. Weight loss and exercise also help keep blood sugars under control, which may prevent kidney disease and other complications such as eyesight loss and nerve problems.

Correct thyroid condition

Hypothyroidism occurs when the thyroid gland doesn’t produce adequate thyroid hormones to regulate the body’s functioning. This causes a slowing of metabolism, including weight gain, lethargy, and hair loss, and contributes to high cholesterol levels in dogs. Treatment includes thyroid replacement medications such as levothyroxine. 

Hyperthyroidism occurs when the thyroid gland produces too much thyroid hormone, leading to cardiac rate and rhythm problems, high blood pressure and other ailments. Treatment includes administration of an anti-thyroid hormone drug called a thionamide.

Lowering high blood pressure

For high blood pressure, dogs may be treated with antihypertensives such as ACE Inhibitors. They may also be put on weight loss diets with exercise to help control the condition. Diuretics may be given to decrease the volume of the blood flowing through possibly constricted blood vessels. 

As with any medications, drugs to control blood pressure and cholesterol carry side effects and risks, but your veterinarian has deemed the risk to be lower than not treating the underlying condition. The treatments that are recommended will usually need to be continued throughout the dog’s life.

There is no cure for atherosclerosis, but the condition can be slowed by treatment. Life expectancy may be shortened. A dog who is diagnosed with atherosclerosis will require regular visits to the veterinarian to assess their level of function and the status of their condition. 

Medication dosages may need to be adjusted according to the dog’s response. Treatment will continue throughout your dog’s life, and can include lifestyle changes like diet and exercise. Stress-relief and adequate rest will contribute to successful management of atherosclerosis as well. 

Atherosclerosis can be expensive to treat. If you suspect your dog is at risk of developing this condition, start searching for pet insurance today. Wag! Wellness lets pet parents compare insurance plans from leading companies like PetPlan and Embrace. Find the “pawfect” plan for your pet in just a few clicks!

Average cost of treatment: $500 to $10,000