The kidneys play an important role in filtering waste from the blood and balancing the amount of water in the body. If the kidneys stop working it can cause some serious problems for your dog, and make him feel very unwell.
Some dogs are born with a kidney birth defect, other dogs develop kidney disease as a result of old age, high blood pressure, a bacterial infection, or from ingesting poison.
Often the signs of kidney disease go totally unnoticed until the dog has lost 2/3 of its kidney function! That’s why it is important to catch this disease early.
In this article, we will discuss the different types of kidney disease in dogs and the common signs you should watch out for. We will also take a look at how it is diagnosed and the best treatment options for your dog.
That way you can be fully informed to make the best decisions for your beloved pooch.
What Do The Kidneys Do?
There are two kidneys in the dog’s body, and each one acts as a complex filter to remove waste from the blood. These waste products are then passed onto the bladder, where they leave the body as urine.
However, you might be surprised that the kidneys have a number of important roles in the body including:
- Remove waste products from the blood
- Remove drugs from the body
- Produce urine
- Balance the amount of water and salts in the body
- Regulate blood pressure
- Regulate levels of calcium and vitamin D
- Help produce new red blood cells
This youtube video explains the functions and anatomy of the dog’s kidneys in a lot more detail.
So, it is pretty obvious that the kidneys are very important! If the kidneys aren’t working, then the dog will have some major problems.
What Is Kidney Disease?
Kidney disease or renal disease is any condition that causes damage to one or both kidneys. When the kidneys are not functioning as they should be, it causes a build-up of waste products in the blood.
It also causes more water than normal to be lost in the urine, quickly leading to dehydration.
Kidney failure is when 75% of kidney function has been lost.
Kidney disease is usually described as either acute or chronic.
1.Acute Kidney Disease
A condition when kidney function suddenly decreases over days or weeks. This is usually associated with infections, toxins or poisons. Acute kidney disease is usually reversible if caught early.
2. Chronic Kidney Disease
Chronic kidney disease means the damage to the kidneys has been ongoing for weeks, months or years. It is usually caused by old age changes or a long term disease.
Chronic kidney disease is not reversible, but it can often be managed with appropriate medication and diet.
Signs Of Kidney Disease In Dogs
The signs of kidney disease in dogs can vary a lot depending on the underlying cause and how long the dog has been affected.
It is more common for dogs with chronic kidney disease to show subtle signs and a slow progression. However, in both acute and chronic disease, sometimes the signs can appear very suddenly!
Common signs of kidney disease include:
- Increased drinking (polydipsia)
- Increased urination (polyuria)
- Decreased appetite
- Weight loss
- Lethargy and depression
- Anemia: pale gums and weakness
- Very bad breath (halitosis)
Less common signs of kidney disease include:
- Ulcers in the mouth
- Weakened bones leading to fractures
- Sudden blindness, from a very high blood pressure
- Itchy skin, from calcium and phosphorus deposits on the skin
- Internal bleeding or bruising of the skin
- Not producing any urine at all
Many of the symptoms of kidney disease, only appear when 2/3 of the kidney’s function has been lost. That is why early detection of this disease is extremely important!
What Causes Kidney Disease?
Kidney disease has many possible causes. Let’s look at some of the most common causes of kidney disease in dogs in a little more detail:
1. Old Age Degeneration
As the dog’s kidneys get older the cells naturally start to slow down and stop working. This is a common cause of kidney disease. This study found that chronic kidney disease was more commonly diagnosed in dogs over 12 years of age.
This whole process might be sped up if the dog eats a poor diet, gets a urinary tract infection, or is suffering from other diseases. (1)
2. Bacterial Infection
Leptospirosis is a common bacterial infection that can cause kidney disease in dogs. The AVMA reports dogs usually get infected from swimming in lakes, rivers or infected water sources (rats and other wildlife are sources of infection).
Inflammation of the kidneys due to a severe bacterial infection is called pyelonephritis. The infection can enter the kidneys from the bladder (urinary tract infection [UTI]), or from the bloodstream.
This study found that E. coli and Staphylococcus spp. were the two most common bacteria found in the kidneys.
Certain human medications (e.g. ibuprofen), food (e.g. grapes) or common household products (e.g. antifreeze) can cause severe damage to your dog’s kidneys.
The pet poison helpline says as little as a tablespoon of antifreeze can result in severe acute kidney failure in dogs. Therefore, it is important to keep these things out of reach from your dog.
4. Congenital Or Inherited Disease
Some dogs have a congenital disease of the kidneys, meaning they are born with a kidney defect. Other kidney conditions are inherited and develop later. Dogs with congenital or inherited kidney defects, normally show signs younger than 5 years of age.
The Merck Vet Manual lists some common kidney defects including renal agenesis (born without one or both kidneys) and polycystic kidneys.
5. Changes In Blood Pressure
The kidneys are susceptible to damage if there is a big change in blood pressure within the body. If there is uncontrolled high blood pressure (hypertension) it causes blood vessels in and around the kidneys to become damaged, making them unable to deliver blood to the kidney tissue which results in kidney damage.
The most common cause of high blood pressure is heart failure. If there is very low blood pressure (hypotension), for example from blood loss or shock, then there isn’t enough blood and oxygen entering the kidneys either. This can also quickly cause kidney damage.
Are Some Dog Breeds At Higher Risk Of Kidney Disease?
Generally older, smaller dog breeds tend to develop kidney disease more often than larger breeds. However, some dog breeds have been identified as more likely to develop kidney disease than others.
How Is Kidney Disease Diagnosed?
Your veterinarian will be able to diagnose if your dog has kidney disease. Usually, a simple blood test and urinalysis are all it takes.
The vet will ask you questions about your dog’s current signs such as what symptoms he is showing when the symptoms started if he is eating and drinking normally etc.
This information is very important as it helps the vet decide what possible problems your dog might have.
2. Physical Exam
The vet will give your dog a full clinical examination, checking things like his heart and lungs, and temperature. The color of the gums (mucous membranes) will be checked, they might be paler than normal if the dog has anemia.
The dog will be checked for signs of dehydration, such as the gums being drier than normal and the skin taking a long time to return to its normal position when pinched.
The abdomen (belly) will be checked for pain, swellings or excess fluid (ascites).
3. Blood Tests
- Complete blood count: This test checks the levels of red blood cells, white blood cells, and platelets in the body. It can give an indication of dehydration, anemia, inflammation or infection in the dog’s body.
- Serum biochemistry: This checks the general health of some of the dog’s organs, as well as the levels of some proteins, fats, minerals, and electrolytes. If a dog has kidney disease, there will usually be an increase in the kidney enzymes (blood urea nitrogen [BUN] and creatinine) and the mineral phosphorus.
- SDMA: Symmetric dimethylarginine (SDMA) is excreted by the kidneys, and increases when there is kidney damage. This enzyme increases much sooner than BUN or creatinine levels, which means it is a very reliable test at picking up kidney disease sooner.
- Urinalysis: A urine sample is an important part of assessing the health of the kidneys and urinary tract. A sample of urine will be analyzed to check its concentration and to check for abnormal levels of protein, blood, white blood cells, bacteria and sugar (glucose). A dog with healthy kidneys should produce concentrated urine, while watery (dilute) urine is a common sign of kidney disease. Another sign of kidney disease is when there is excess protein in the urine (proteinuria).
What Other Tests Might Be Needed?
Once a dog has been diagnosed with kidney disease, other tests are often needed to check for an underlying cause and to “stage” the kidney disease (check the severity of the kidney disease). These further tests are important to ensure the dog can receive the best treatment, monitoring, and care.
1. Ultrasound And X-rays
Imaging allows the vet to check the size, shape, and location of the kidneys, and to look for abnormalities such as kidney stones, cancer or cysts. Usually, in chronic kidney disease, the kidneys are smaller than normal, as they are no longer working well.
2. Bacterial Culture
If bacteria are found in the dog’s urine sample, it should be submitted to a lab for bacterial culture. This will show which type of bacteria is present, and which antibiotics are best to use to treat the infection.
3. Blood Pressure
High blood pressure (hypertension) is a common consequence of kidney disease in dogs. If high blood pressure isn’t diagnosed and treated, it can lead to the kidney disease getting worse, or even cause heart problems and blindness.
4. Kidney Biopsy
A kidney biopsy can help figure out the underlying cause of kidney disease. The cells/tissue that is collected is examined at a specialist laboratory.
5. Clotting Tests
Some dogs with kidney disease may have a blood clotting problem. If a dog is scheduled to undergo a surgery or a kidney biopsy, this test is completed in advance to check the dog’s ability to stop bleeding.
Common signs of a blood clotting problem, include:
- skin bruising
- bleeding after a blood sample is taken
- pale gums
What Is Kidney Disease Staging?
Staging kidney disease is a way to estimate the severity of the dog’s kidney disease so that it can be treated and managed in the best possible way.
Veterinarians normally use the International Renal Interest Society (IRIS) method to estimate the stages of CKD. Stages are numbered from 1 to 4, with four being the most serious and severe.
The stage of kidney disease can be estimated based on the levels of urea, creatinine, and SDMA, as well as the levels of protein in the urine and the dog’s blood pressure.
What Are The Treatment Options?
Every dog with kidney disease will need an individually tailored treatment plan depending on the severity of the disease, and the underlying cause. Let’s look at the most common treatment options for dogs with kidney disease:
1. Fluid Therapy
Dogs with severe signs are usually hospitalized for intravenous fluid therapy. This helps to take the pressure off the kidneys, flush out the build of waste products (e.g. urea) in the body and rehydrate the dog.
Some dogs with mild signs of dehydration may be managed with subcutaneous fluids (under the skin).
2. Anti-Sickness Medication
Dogs with kidney disease often have vomiting and signs of nausea and need to be treated with anti-sickness medication. This medication will improve the dog’s appetite.
Dogs with kidney disease should be transitioned onto a kidney support diet, as studies show that it is the best way to treat and manage this disease.
A study in dogs showed that it is an effective way of improving survival, quality of life and slowing the progression of the disease. (3)
Kidney support diets contain less protein, sodium, and phosphorus, and increased omega-3 fatty acids than regular dog food.
These diets are formulated to help reduce the workload of the kidneys and slow the progression of the disease.
A course of antibiotics is needed if the dog has a urinary tract infection. If the kidneys are also infected (pyelonephritis) then the treatment course is much longer than an infection of the bladder.
The dog’s urine will need to be retested to ensure the infection has been successfully treated.
5. Blood Pressure Medication
High blood pressure can be treated with medication such as angiotensin-converting enzyme inhibitor (ACEI, such as benazepril). Dogs will need to have their blood pressure monitored regularly.
6. Kidney Dialysis Or Kidney Transplant
Dialysis or kidney transplant are not common treatment options in veterinary medicine yet. These treatment options may be a possibility for those pet owners who can afford the high cost of treatment in specialist veterinary referral centers.
**This information is not meant to be a substitute for veterinary care, and you should seek veterinary help as soon as possible if you think your dog is showing signs of kidney disease**
Does Kidney Disease In Dogs Need Long Term Care?
This depends if the kidney disease is acute or chronic. In some cases of acute kidney disease, the damage to the kidneys may be reversible if it is caught early and treated aggressively with fluids and other medications. These dogs might recover and not need life long care.
However, chronic kidney disease is not curable, as the damage to the kidneys can not be reversed. This means the dog will need life long management and care.
Most dogs are transitioned onto a kidney support diet as this will really help manage their disease. As they can easily become dehydrated, they need to be encouraged to drink extra water, by putting extra water bowls down, using canine flavored water (e.g. oralade) or adding some broth to the dog food. Some dogs may need life long blood pressure medication too.
Dogs with kidney disease will need regular vet check-ups to monitor their disease, this might involve a urine test and blood test too.
Can Kidney Disease Be Prevented?
Chronic kidney disease is not considered preventable, as it is most likely a result of genetics and old-age changes.
Usually, once your dog has started showing the common clinical signs of kidney disease, the disease has already progressed and caused a lot of irreversible damage to the kidneys.
However, if it were to be diagnosed early your dog would really benefit from early treatment. This is why it is important to bring your dog for his annual veterinary checkup and wellness exam.
This is especially important for older dogs, even if you think he is healthy there could be some underlying problems.
A health screening blood test and urine sample could pick up on the early changes in kidney disease before he starts showing obvious signs!
Some types of acute kidney disease can be prevented. Here are some easy ways to help prevent kidney disease in your dog:
- There are vaccinations against some infectious diseases which can cause kidney failure, such as canine adenovirus and leptospirosis.
- Keep household toxins, such as antifreeze, in a secure location.
- Keep all human medications in a secure location.
- Don’t feed your dog grapes or raisins.
A simple blood and urine test is all it takes to find out if your dog has kidney disease. The sooner kidney disease is diagnosed the better, that’s why it’s important to regularly screen older dogs for this common condition.
A good quality kidney support diet has been shown to be a really important factor in helping dogs cope with this disease.
With recent advances in medicine, nutrition, and renal drugs, many dogs with chronic kidney disease can continue to live long lives.
If your dog has been diagnosed with chronic kidney disease, he can often continue to live a happy life with your support and the help of your veterinarian.