Anemia Due To Chronic Kidney Disease in Dogs

The kidneys are one of the weaker organs in dogs, and chronic disease and failure of the kidneys are common among older dogs. Nephrons in the kidneys contain filtering structures called glomeruli which eliminate waste and toxicity from the blood. The glomeruli tend to become less functional with age, and their effectiveness can also be reduced by conditions that increase levels of protein and inflammatory cells in the blood. The kidneys also produce erythropoietin, a hormone that stimulates the production of red blood cells in the bone marrow, so, as large numbers of nephrons become dysfunctional chronic, non-regenerative anemia develops. Symptoms of inflammation and uremia, both of which are common with kidney failure, further contribute to the reduction in red blood cells.  Anemia is one of the more advanced symptoms of kidney disease. It can be rebalanced with hormone replacement therapy, but the chance of overall recovery is poor.

As the kidneys lose function in dogs, they fail to produce the hormones that normally stimulate red blood cell production. A type of non-regenerative anemia develops as the bone marrow is no longer able replace lost blood cells. This condition is treatable in the short term, but the chance of full recovery from chronic kidney disease is low.

Constant drinking and excessive urination are usually the first signs as the body compensates for reduced kidney function. It’s a good idea to discuss these symptoms with a veterinarian if possible. By the time anemia has developed, symptoms will be more severe. Take your dog to see a veterinarian as soon as possible if you notice any of the following signs of anemia or kidney disease:

• Weight loss
• Poor appetite
• Lethargy
• Lack of stamina
• Weakness
• Rapid heart rate (tachycardia)
• Rapid breathing (tachypnea)
• Paleness of mucus membranes, especially around the gums
• Blood in the stool
• Excessive drinking and urination
• Lusterless, unkempt coat
• Vomiting
• Diarrhea
• Reduced urine output
• Hunched posture or other signs of pain

Types

Anemia is divided into two types:

• Regenerative anemia – anemia in which the bone marrow is able to compensate for a decrease in red blood cells
• Non-regenerative anemia – anemia in which the body is unable to compensate naturally. Anemia due to chronic kidney disease falls into this category because the hormone imbalance negatively affects bone marrow production. Other types of non-regenerative anemia are usually due directly to bone marrow failure.

It’s often hard to determine the exact cause of kidney disease in dogs. It is more common in older dogs, but there are sometimes other contributing factors:

• Age
• Viral, bacterial or parasite infection (including leptospirosis and Lyme disease)
• Diabetes
• High blood pressure
• Chronic inflammation
• Autoimmune diseases
• Overactive adrenaline gland
• Amyloidosis – a genetic abnormality more common among Shar Peis and Akitas
• Other hereditary condition
• Tumor in the thyroid gland
• Bladder or kidney stones

The veterinarian will be able to diagnose your dog’s anemia with a blood test. A complete blood count (CBC) will show reduced levels of red blood cells. Urine analysis, as well as high levels of toxic compounds in the blood, will suggest kidney disease. Specific tests such as a urine gravity test, protein analysis and levels of nitrogen, calcium, and potassium in the blood will help to determine the severity of the problem. High blood pressure is also common with kidney disease. The veterinarian may order ultrasound or X-rays show to abnormalities in the kidney size. This can help to distinguish between chronic kidney disease and cancerous tumors on the kidneys.

The veterinarian will need to know your dog’s medical history, and any significant conditions like diabetes or chronic inflammatory conditions. A detailed description of your dog’s symptoms and time of onset will also be necessary. Discussing the earliest symptoms of kidney problems with your vet can help get your dog supportive treatment as soon as possible, so it’s important to mention signs like increased drinking or excessive urination. Once clinical symptoms of anemia are present, it suggests a fairly advanced degree of kidney dysfunction.

Severe anemia due to chronic kidney disease is usually treated with recombinant human erythropoietin. This medication helps to replace the natural erythropoietin produced by the kidneys and will therefore stimulate red blood cell production in the bone marrow. As the name suggests however, the drug was developed to replace human erythropoietin which is only 81.3% similar to the canine version. It is usually effective to start with, but, at some point, the dog’s immune system may reject it, and it may actually have a negative effect on red blood cell production. The medication is given 3 times per week at varying doses based on weight. Once the blood reaches a target level (usually after about 3-4 weeks) the doses are reduced. Iron supplements should be prescribed at the same time.

Other treatments for kidney failure will depend on the degree of kidney dysfunction in your dog. Early signs are usually treated with diet change. Some pet food is made with lower protein and sodium levels, specifically for dogs with kidney problems. If the veterinarian suggests this type of diet, it is a good idea to have regular check-ups and blood tests to ensure that your dog is still getting good nutrition.  The veterinarian may also suggest a home-made diet, or prescribe vitamin and mineral supplements to make up for poor nutrient absorption. This can help to prevent the development of anemia and keep symptoms of mild anemia at bay as long as possible. 

Ace inhibitors can sometimes be prescribed to decrease the rate of nephron destruction, but they usually become less effective as the condition progresses. The veterinarian may also recommend dialysis appointments to reduce toxicity levels in the blood. Very severe cases of anemia could require blood transfusions.

Organ transplants are rare in animals, but this would be the most effective long-term treatment for chronic kidney disease. An acceptable donor would need to be found. This treatment would include potentially risky surgery as well as the possibility that your dog’s body might reject the new organ. The possibility of this type of treatment would have to be evaluated by a veterinarian.

It’s unlikely that your dog will make a full recovery from chronic kidney disease, unless the veterinarian is able to perform a successful transplant (which is rare.) Diet, medication and other treatments can help to reduce symptoms and delay progression, however, and it’s possible your dog may survive for a number of years after the first signs become noticeable. You should always ensure your dog is getting plenty of water to help make up for reduced kidney function. Eventually, you may need to administer extra fluids through an eye dropper.  As time progresses, medication and other treatments will become more and more extensive.