Where are dogs kidneys located: Your dog’s kidneys & how they work

Your dog’s kidneys & how they work

I’ve written about kidney failure on a few occasions in the past – what it is and how it can be treated.

But what I haven’t spoken about is what the kidneys are. What exactly do these bean-shaped organs do and why is keeping them healthy so important to your dog’s overall health?

Though they be small…

Like humans, dogs are born (in the majority of cases) with two kidneys. They’re situated – one on either side – at the back of your dog’s body in the abdominal cavity just under the backbone. Close to where the spine and last rib meet.

Shaped like their namesake beans, each kidney is not much bigger than 3-5.3 cm for small dogs up to 6.6 – 9.3 cm for large dogs, and is comprised of microscope structures that help it carry out its plethora of functions. The most important of these is the nephron. This tiny structure is itself comprised of a renal corpuscle and a renal tubule, all of which work together to help the kidneys perform their many tasks.

At birth, each kidney contains about 1 million nephrons, the number of which diminish over time, something which in part can contribute to kidney problems. This is because the nephrons act as a kind of filtration system which allow the body to retain substances it needs and to remove toxins and other unnecessary substances.

…they be mighty

Despite their relatively small size, kidneys carry out a whole range of functions that are vital to keeping your dog healthy, indeed alive. This is epitomised by how ill dogs can become when they stop working properly.

While many people have some idea of the role of the kidneys, not many know the full extent of what these little organs are capable of.

Toxin removal:

The kidney function that you’re likely to have heard of is toxin removal. Using their internal filtration system, the kidney’s work to distinguish between substances that the body needs and ones it doesn’t and to aid the expulsion of these substances from the body in the form of urine.

Urine is typically comprised of water, metabolic waste and toxins.

Metabolic waste is the broad term given to compounds and substances which are by-products of normal cellular process like respiration and digestion. These ‘left-over’ substances can’t be used by the body (either they’re surplus or they’re toxic) and so must be removed by the kidneys. Examples of compounds that are considered metabolic waste include nitrogen, carbon dioxide and sulphates.

While metabolic waste isn’t necessarily poisonous, toxins (which are a type of metabolic waste) are. These compounds are produced within and by living cells / organisms and can cause a lot of harm if allowed to accumulate within the body or if they are absorbed by bodily tissues. For this reason, the kidneys work to identify these toxins and expunge them from the body. Examples of toxins include peptides and small molecules.

Water Conservation:

It’s a simple fact that your dog needs water to survive. But did you know that keeping your dog hydrated is a balancing act between water conservation and water removal. And the kidneys play a vital role in maintaining this delicate balancing act.

When your dog is sufficiently hydrated, their kidney’s go about their job as usual. However, in those instances when your dog is dehydrated (which could be for any number of reasons), their kidneys have to switch gear. They need to work to retain and conserve as much water as possible while still removing metabolic waste and toxins. They do this by mixing these toxins and waste with as little water as possible, which is why concentrated urine (yellow in colour) could be a sign that your dog is dehydrated.

Conversely, if your dog drinks a lot of water, the kidneys will work to remove the unnecessary / excess water as quickly as possible, so as to avoid dilution of the blood. In these instances, your dog’s urine will be very dilute (clear in colour).

Sodium/Potassium Balance:

Among the various, complex compounds that need to be regulated to keep your dog healthy are a group of substances known as electrolytes. Sodium and potassium are among the more well-known electrolytes and they’re important because when dissolved in blood they help:

• regulate muscle and nerve function
• maintain acid-base levels
• maintain normal fluid levels in fluid compartments

It’s unsurprising therefore that a change in the levels of these electrolytes – and indeed the balance between them – can lead to damage and health problems for your dog. This is where their kidneys come in. In a series of complex steps involving sensors and regulators, these small organs filter water and electrolytes out from the blood, then return what’s needed to the blood and excrete anything that’s surplus to requirements via urine.

In this way, the kidneys help maintain sodium and potassium levels, the correct balance between them, and the levels of other electrolytes.

Blood Pressure Regulation:

One of the lesser-known functions of the kidneys is their involvement in blood pressure regulation. As a reminder, blood pressure is the pressure required for the arteries in your dog’s heart to carry blood from the heart to the rest of the body. And there’s a healthy range within which your dog’s blood pressure should always be.

There are two ways in which the kidneys keep your dog’s blood pressure in check:

• hormonally
  • Within their complex structure, the kidneys also contain sensors which monitor blood volume as it passes through the kidneys. When these volumes are low, it’s detected by these sensors which in turn stimulates the release of a hormone called renin. When this happens, it triggers a cascade of events that stimulates the kidneys to retain sodium and water, and blood vessels to constrict, all of which raises blood pressure.

• maintenance of the fluid circulation
  • We’ve already spoken about how the kidneys help regulate sodium and potassium levels. Well these electrolytes are also involved in blood pressure regulation. By regulating the levels of these electrolytes, your dog’s kidneys are also regulating their blood pressure. This is because these substances are involved in maintaining blood volume which in turn is involved in blood pressure regulation.

Calcium/Phosphorus Balance:

In a similar way to how they maintain a balance between electrolytes, the kidneys also regulate the levels of ions including calcium and phosphorus in your dog’s body. They do this through a series of complex processes involving different hormones, pathways, channels and transporters, which ultimately cumulate in the filtration of these ions out of the blood and their subsequent reabsorption or excretion.

It’s important that the kidneys regulate calcium and phosphorus levels accurately as an imbalance in their levels can lead to various disorders including skeletal problems, seizures, arrythmias and respiratory problems.

Red Blood Cell Production:

It might sound odd, but the kidneys also play a big role in the production of red blood cells. These round, flat cells are made in the bone marrow inside your dog’s bones and contain a protein called haemoglobin. It is this protein, inside red blood cells, which is what allows them to carry fresh oxygen around the body.

So, if these important cells are made in the bone marrow, what do the kidneys have to do with their production? Put simply – the kidneys help regulate when red blood cells should be produced. They do so by producing a hormone called erythropoietin (ERO). When it’s produced and released from the kidneys into the blood, ERO in turn prompts and stimulates the bone marrow to produce new red blood cells.

This means that while the kidneys aren’t directly involved in actually producing red blood cells, they indirectly stimulate their production in the bone marrow through release of the hormone ERO.

Protein Conservation:

Proteins are the building blocks of life, and as such, are very important for your dog’s overall health. This means that when filtering your dog’s blood, the kidneys do not want to remove all the proteins from the blood. Doing so would be dangerous and could cause damage to your dog’s health.

For this reason, the kidneys have mechanisms in place that ensure they only filter out and expel the tiniest amounts of protein (typically excess levels or those under a certain size). These same mechanisms mean that bigger proteins (which are typically those required to carry out various bodily functions) are not filtered out by the kidneys, but instead are reabsorbed into the blood where they’re needed.

The take home message

Your dog’s kidneys are vital to their survival in lots of different ways, some more obvious than others. That’s why it’s important to ensure you feed them a diet that helps to keep their kidneys working at an optimal, healthy level. Doing so will help ensure your dog remains happy and healthy.

Learn more 

Diet for dogs with kidney disease

Analysis of a generic home-prepared dog diet

Our consultations 

How much protein should you feed your dog?

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Kidney failure in dogs: symptoms, diagnosis and treatment

Your dog is peeing more than usual, drinking copious amounts of water and seems to be sending you a signal that something just isn’t right.

If you suspect kidney disease, a vet visit is needed, stat.

“The sooner the signs of kidney failure in dogs are recognized, the earlier the diagnosis of kidney disease can be made and the easier we can slow down the progression of the disease,” says veterinarian Dr. JD Foster, who works in the Internal Medicine department at Friendship Hospital for Animals in Washington, D.C.

Kidney disease is a condition that can look innocuous, can have the same signs as other diseases or sometimes have no recognizable symptoms at all, so it’s important to get a vet’s input about what is happening. To help you better understand the diagnosis, here’s a breakdown of signs, how it’s diagnosed and what you can expect by way of treatment.

What is kidney disease?

Sometimes called kidney (renal) failure, kidney disease occurs when a dog’s kidneys aren’t able to do their job, which is to remove toxins from the dog’s body. Dogs have two kidneys located within the abdomen along the spine, atop the bladder.

“The kidney is entirely responsible for maintaining the entire body’s homeostasis, which includes water balance, balancing electrolytes and maintaining blood pressure,” says Foster.

The kidneys aren’t just responsible for producing urine but also for regulating these systems.

“Urine is just a byproduct of all the other functions that the kidney does,” Foster says. “So when we see problems with the kidneys, all of these areas can be affected, including digestion and metabolism.”

There are two types of kidney disease: acute and chronic.

Acute kidney injury

Acute kidney injury (AKI) is often sudden and progresses rapidly, while chronic kidney disease takes much longer to manifest.

“Acute kidney failure can be due to injury or decreased blood flow to the body,” Foster says. “Or toxins can cause acute kidney injury. We really try to treat those underlying causes to give the best chance for recovery.”

Some of the causes of AKI include:

• Infections (like bacterial infection of the kidney)

• Toxins (like antifreeze; NSAIDs like aspirin; foods like grapes, raisins, currants)

• Some medications

Chronic kidney disease

Chronic kidney disease (CKD) may be congenital, Foster notes, but most patients acquire kidney disease as they age.

“The cause of CKD is very challenging to determine, as it likely initiated months to years prior to the time of diagnosis,” he says.

What are the signs of kidney disease?

When it comes to kidney disease, there are certain symptoms that should spark concern right away.

“The most alarming symptoms include vomiting/anorexia, as well as a decrease in urine production,” Foster says. “While other things may also cause these symptoms, they should prompt an immediate visit to the veterinarian for evaluation. From the vet side, we may see oral ulcers, detect the presence of uremic toxins in the breath and may possibly feel abnormal kidney shape or size during our examination.”

Other symptoms

A sudden change in your dog’s well-being

“When your dog is suddenly acting very sick, this could mean acute kidney injury, but it might not be,” Foster says. “There can be many reasons why dogs suddenly seem very sick.”

A trip to the emergency vet is vital when sudden changes occur.

Your dog is urinating more frequently

This can be one of the first signs of acute or chronic kidney disease.

“If you find yourself having to take your dog out for a pee more frequently, keep track,” says Dr. Kimberly Hammer, a veterinarian at NorthStar VETS in Robbinsville, New Jersey, and a diplomate of the American College of Veterinary Internal Medicine.

A decreased appetite

“If your dog suddenly does not want to eat, is anorexic and seems generally unwell, this could mean acute kidney failure,” says Foster. “If your dog seems to lose interest in his usual dog food and will only eat scraps and treats, this could signal kidney disease.”

Extreme lethargy

“If your dog just seems really tired, unwell and does not want to do anything, this might signal acute kidney injury, especially if accompanied by recent trauma to the kidney area,” says Foster.

And if you notice your happy, healthy dog getting more and more tired over time, this could indicate chronic kidney failure, he warns.

Excessive thirst

“If you find yourself needing to fill the water bowl up more frequently or find your dog looking for extra water sources, this could signal chronic kidney failure,” says Hammer.

Bad breath

Pets might “start to develop bad breath (that is quite noticeable) due to the toxins accumulated in their bodies,” says Hammer.

Changes to your dog’s bone structures

“They might develop a swelling on both sides of their face along the upper jaw, which is a complication of imbalances in their bodies,” says Foster. “This isn’t common but could raise a red flag.”

Diarrhea or constipation

Because the kidneys regulate the fluids in the body, you might see issues and changes concerning your dog’s bowel movements.

If you observe any of these signs in your dog, be sure to contact your vet.

How is kidney disease diagnosed?

Kidney disease is diagnosed by a combination of bloodwork and urine testing, Foster says.

“Most clients can expect to have a CBC (complete blood count), biochemistry panel and full urinalysis performed,” he says. “Cost for these three tests are likely $200 to $400, depending on where you live. After kidney disease is suspected, further testing will likely be recommended.”

Foster says additional tests may include radiographs ($150 to $300), ultrasound ($300 to $600), urine culture ($100 to $200), blood pressure ($25 to $50) and other tests in some circumstances.

How is kidney disease treated?

Treatment for chronic kidney disease is multifaceted. It’s focused around nutrition, maintaining hydration, correction of anemia and normalization of electrolyte disturbances, according to Foster.

“Most dogs should be eating a prescription diet made for kidney disease; these foods have been shown to improve survival and reduce complications associated with kidney disease,” Foster says, adding that if a dog doesn’t like the taste of one type of diet, there are plenty of options available.

Keeping the dog hydrated is important and that can be managed, he says, by feeding a canned diet, adding extra water to the food, using esophageal feeding tubes or via subcutaneous fluids.

“Medications may need to be given to help keep their phosphorus and potassium concentrations normal,” Foster says. “If dogs become significantly anemic (due to a deficiency in erythropoetin, a hormone made by the kidneys), injections of erythropoetin will be initiated.”

In early stages, diet may be the only needed treatment. As the disease progresses, Foster says, your dog may require additional therapies.

Acute kidney injury is treated similarly, he notes, but many dogs are sick and require hospitalization for IV fluids and medications.

“Some may have severe enough disease where they require hemodialysis to help remove the toxins that have accumulated within the dog that is causing disease,” Foster says. “Dialysis can help a dog feel better, improving their quality of life as their kidneys heal. Dialysis can also be performed for dogs with advanced CKD, although their scenario is similar to people who receive dialysis — typically two to three times a week treatments are needed for the rest of the dog’s life.”

Dogs with AKI may only need dialysis over the course of one to four weeks; however, some patients may require a longer course of treatment.

What is the prognosis for a dog with kidney disease?

Obviously, your vet will be the one to determine what lies ahead should kidney disease be the diagnosis. In general, Foster says the prognosis for dogs with acute kidney injury is guarded, with an overall survival rate of 50% to 65%.

“Dogs with infectious disease (like leptospirosis) have a better survival than those who have had a toxin exposure,” he says.

Dogs with chronic kidney disease experience shorter survival rates as their disease progresses, he says, adding that veterinarians use the International Renal Interest Society (IRIS) staging system to characterize the severity of the dog’s condition, with the survival rate shortening as the stages advance.

“Stage I has an average survival of more than 400 days, Stage II 200 days, Stage III 100 days and Stage IV 14 to 100 days,” he says. “These survival statistics are old and retrospective. I generally see much better survival times for the patients I manage. The treatment for CKD is designed to slow the progression of disease; however, given enough time, dogs will advance in their disease severity and eventually we will be unable to provide them with a good quality of life. ”

Ultrasound picture of the kidneys in dogs is normal

To assess the presence of kidney pathology in dogs, it is necessary to know the normal parameters and signs of the ultrasonic norm of these organs.
Kidneys are assessed by:

– degrees of visualization

– localization

– size

– form

– echogenicity of structures

– the ratio of cortical and medulla

– width and echogenicity of the pelvis
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– even contours

– clear boundaries

– clarity of cortical-cerebral differentiation

Normally, the kidneys are symmetrical in shape and size. The right kidney is cranial to the left, and can be located almost entirely in the right hypochondrium.

Kidney size:

In dogs, estimation of kidney size is difficult due to the large range of values.

To date, there are two main methods for assessing the size of the kidneys in dogs.
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– Comparison of the size of the kidney and the length of the body of the second lumbar vertebra.

The normal length of the kidney should be from 2.5 to 3.5 of the length of the body of the second lumbar vertebra

– The ratio of the length of the kidney and the diameter of the aorta at the level of the kidney at the time of maximum expansion.

Kidneys are considered to be reduced if the ratio of kidney length to aortic diameter is less than 5.5 and enlarged if the ratio is greater than 9.1 (Mareschal et al., 2007)

The shape can be oval or bean-shaped. The ratio of cortical and medulla is 1:1. The echogenicity of the cortical substance is reduced compared with the echogenicity of the parenchyma of the spleen. The echogenicity of the medulla is lower than the echogenicity of the cortical. The renal pelvis is better visualized with a transverse scan of the kidney in its central part. The connective tissue framework of the pelvis has increased echogenicity and is visualized in the form of a horseshoe. The cavity of the pelvis is visualized as an anechoic crescent-shaped or horseshoe-shaped area between the connective tissue backbone and the renal crest. The cavity of the pelvis should not normally exceed 2 mm.
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The contours of the kidneys are normally even, the boundaries are clear.

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Kidney disease in dogs – symptoms and treatment, diet for kidney disease in dogs in Moscow. Veterinary clinic “Zoostatus”

Acute renal failure of
Chronic renal failure
pyelonephritis
glomerulonephritis
Amyloidosis of the kidneys
hydronephrosis
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The kidneys are a paired organ located in the retroperitoneal space and responsible for maintaining the body’s homeostasis by performing excretory, endocrine, and metabolic functions. The kidneys maintain the osmotic pressure of the blood, provide regulation of the ionic balance, and take part in hematopoiesis due to the production of erythropoietin.

Kidney disease in dogs is a common reason for visiting a veterinarian.

Acute renal failure

Acute renal failure is a condition in which, within a short time (several hours or days), the level of glomerular filtration decreases significantly, nitrogenous metabolic products accumulate in the blood, and the amount of urine produced decreases sharply (oliguria) up to complete absence of urine (anuria). ).

Acute renal failure may develop due to factors not related to the urinary system (prerenal renal failure): shock, blockage of large vessels, a significant decrease in blood pressure, dehydration. These factors disrupt the blood supply to the kidneys, causing hypoxia of the renal tissue. nine0004

Postrenal renal insufficiency is a consequence of impaired urine flow.

Renal renal failure is caused by thrombosis of the renal vessels, inflammation and toxic damage to the renal tissue.

Acute renal failure is characterized by rapid development of symptoms, severe general condition. Without timely treatment, the animal usually dies.

If time is not lost, and the causes of the disease can be eliminated, then with adequate treatment, complete restoration of renal function is possible. Treatment of acute renal failure should be carried out in a hospital setting. nine0004

Chronic renal failure

Chronic renal failure is a condition in which there is a progressive decline in the ability of the kidneys to perform their functions. Unfortunately, this process is irreversible.

Clinically, renal failure begins when approximately 75% of the nephrons are dead.

Chronic renal failure may develop as a result of a prolonged inflammatory process in the kidneys, glomerulonephritis, pyelonephritis, renal amyloidosis, leptospirosis, polycystic kidney disease, hydronephrosis, hypercalcemia. Quite often, the primary cause of chronic renal failure remains unknown. nine0004

Pyelonephritis

Pylonephritis is usually a bacterial inflammation of the interstitial tissue of the kidneys, renal pelvis, involving the tubules, glomeruli, and vessels of the kidneys. Both kidneys are usually affected.

Most often, pathogens enter the kidneys through the ureters, less often through the lymphogenous and hematogenous routes. Primary pyelonephritis occurs without previous changes, but secondary pyelonephritis is more common, which occurs against the background of stagnation of urine, trauma, endometritis, cystitis, prostatitis, nephrolithiasis, ectopia of the ureters. Perhaps the resulting pyelonephritis is supported by autoimmune processes. nine0004

Glomerulonephritis

Glomerulonephritis is an inflammatory disease affecting the glomeruli and renal corpuscles with further spread to surrounding tissues. It develops as a result of the deposition of antigen-antibody complexes in the glomeruli and subsequent immune reactions.

Sources of antigens often cannot be identified. They can be neoplasms, sepsis, infectious diseases, pyometra, autoimmune diseases.

Renal amyloidosis

Renal amyloidosis is a non-inflammatory disease accompanied by the deposition of amyloid (protein-polysaccharide complex) in the kidneys. Amyloid causes a change in the basement membranes, which leads to significant proteinuria. nine0004

Reliable diagnosis is possible only with a kidney biopsy.

Nephrotic syndrome

Nephrotic syndrome develops in severe glomerulopathy, leading to significant loss of protein in the urine, and, as a result, is accompanied by hypoalbuminemia and the development of edema, ascites and renal failure.

Nephrotic syndrome often develops against the background of renal amyloidosis.

Due to the increased permeability of the membranes of the renal glomeruli, blood proteins are largely lost in the urine, the development of hypoalbuminemia causes a decrease in blood oncotic pressure. Fluid migrates from the bloodstream – edema develops and accumulation of free fluid in the serous cavities (ascites and, less commonly, hydrothorax). The blood supply to the kidneys worsens, salt and water are retained, and blood pressure rises. nine0004

Hydronephrosis

Hydronephrosis is the irreversible enlargement of the renal pelvis and death of the renal parenchyma due to compression atrophy. It develops when the ureter is blocked, when the kidney continues to produce urine. It can be congenital (ureter atresia, ectopia of the ureter orifice, kidney displacement, etc.) and acquired (blockage of the ureter by calculi or neoplasm, compression of the ureter by surrounding tissues (tumors, abscess), iatrogenic damage, neoplasms of the bladder, atony of the bladder, blockage or squeezing of the urethra). nine0004

Unilateral hydronephrosis is often asymptomatic for a long time.

Nephrolithiasis

Nephrolithiasis is the formation of calculi (stones) in the renal pelvis.

More common in bitches. Stones impede the outflow of urine, irritate the tissues of the renal pelvis and lead to its inflammation – pyelitis.

Nephrolithiasis is often an incidental finding, as symptoms are nonspecific or absent.

Renal cysts

Renal cysts are fluid-filled cavities. nine0004

Rare in dogs, may be acquired or congenital. Cairn Terriers have a breed predisposition to the disease.

Large and multiple cysts can lead to atrophy of the renal parenchyma due to compression.

Disorders of tubular conduction

As a result of impaired reabsorption of amino acids, glucose, phosphates, micro- and macroelements, bicarbonates, acidosis, lack of phosphorus, electrolytes and renal failure develop. nine0004

This pathology can be congenital (in dachshunds, basset hounds, basenjis, schnauzers) or acquired (eg, gentamicin poisoning).

Neoplasms

The most common primary kidney tumors are adenocarcinomas that develop in dogs over 6 years of age. In dogs up to a year, nephroblastomas are found. Malignant neoplasms of the kidneys tend to metastasize to the lungs.

Tumors located in other organs often metastasize to the kidneys. nine0004

Kidney neoplasms are usually diagnosed at an advanced stage, when there is a noticeable increase in the size of the affected kidney, or when a noticeable admixture of blood appears in the urine.

In all cases of renal neoplasms, the prognosis is cautious to poor, and removal of the affected kidney as early as possible is usually indicated.

Symptoms of Kidney Disease in Dogs

Signs of kidney disease in dogs are often non-specific and appear late in the disease when kidney function has been largely lost. Symptoms of kidney disease may include:

• Change in urine output (polyuria, oliguria, anuria).
• Change in color and odor of urine.
• Lethargy.
• Weight loss.
• Vomiting, diarrhea.
• Bad breath.
• Wool deterioration.

Diagnosis

When diagnosing dogs with suspected kidney disease, a thorough history taking, general examination, clinical and biochemical blood tests, urinalysis, ultrasound and radiographic examination of the abdominal cavity organs are performed. An x-ray with intravenous contrast (excretory urography) can provide additional information about renal function. nine0004

It is sometimes possible to make a diagnosis only after a kidney biopsy.

Treatment

Treatment of dogs with kidney disease is primarily aimed at eliminating the cause of the disease, if possible.

Measures are also necessarily taken to improve the functioning of the remaining nephrons: improving the perfusion of the kidneys and normalizing the water-salt metabolism due to the infusion of electrolyte solutions.