Azotemia in cats - Types, symptoms and treatment

See Cats files

Azotemia or increased creatinine and urea, It can occur in various situations in cats. Azotemia, depending on its origin, can be divided into prerenal azotemia (when renal perfusion decreases), renal azotemia (due to kidney damage) or postrenal azotemia (alteration in the elimination of urine from the body). The causes can be very diverse, from a dehydration or alteration of the circulatory flow, an intoxication, an electrolyte alteration, a nephrotoxic drug or a pathology of the kidney, to an obstruction of the urinary tract or a uroabdomen.

¿Do you want to know more about the increase in creatinine and urea in little felines? Keep reading this AnimalWised article to learn more about the Azotemia in Cats, Its Types, Symptoms and Treatment.

You may also be interested in: Crystals in urine in cats - Types, symptoms and treatment Index
  1. What is azotemia in cats?
  2. Types of azotemia in cats
  3. What Causes Azotemia in Cats?
  4. Symptoms of azotemia in cats
  5. Diagnosis of azotemia in cats
  6. Treatment of azotemia in cats

What is azotemia in cats?

Azotemia is defined as an increase in non-protein nitrogenous waste products from the blood, with urea and creatinine being the most commonly measured. So to say that a cat has azotemia is to say that the cat have increased urea and creatinine or just one of the two.

¿What is urea?

Urea is a small molecule and end product of protein metabolism formed in the liver in the urea cycle. This substance is filtered through the glomerulus of the kidney and is reabsorbed into the renal tubule and collecting ducts of the kidney..

¿What is creatinine?

Creatinine is a compound that is formed through the breakdown of creatine, a nutrient important for muscles. Creatinine is the waste product created in normal muscle metabolism and is produced at a constant rate, depending on the feline's muscle mass. Finally, it is also filtered in the glomerulus of the kidney but is not reabsorbed later, secreting itself in the urine.

Types of azotemia in cats

There are three types of azotemia in cats. However, in all three there is a decreased renal glomerular filtration with the consequent increase in creatinine and urea.

Feline prerenal azotemia

Prerenal azotemia develops as a consequence of reduced perfusion of the kidney by a disturbance in blood flow, such as hypovolemia, inadequate cardiac output, prominent vasodilation, or dehydration. In these cases, as renal perfusion decreases, the glomerulus filtration rate decreases, which causes a slower clearance of urea and creatinine, appearing in higher concentrations in the blood. Urea is reabsorbed much more, appearing faster in the analysis due to the slower transit in the tubules and ducts. Creatinine is the one that will increase the most slowly, since it is not reabsorbed.

In these cases, cats must continue to concentrate their urine, with a density equal to or greater than 1,035. As the nephrons remain intact, without causing damage or alteration in their functionality, when perfusion is restored, renal function returns to the way it was..

Feline renal azotemia

In renal azotemia, as the name suggests, there has been a kidney damage. A reduction in kidney function between 66-75% leads to an increase in blood urea, after creatinine, with insufficient urine density (1.008-1.012).

However, a density between 1,013 and 1,034 indicates that part of the urine's concentrating capacity is intact, but insufficient to compensate for the losses. In addition, cats with chronic kidney disease retain the ability to concentrate urine for longer than dogs, a density greater than 1,020 can be expected, but it will remain inadequate to prevent azotemia.

Postrenal azotemia

In postrenal azotemia, renal function and glomerular filtration rate is completely normal and efficient, however the excretion products do not leave the body through the urine for a period of time. blockage of urine flow subsequently to the kidneys.

What Causes Azotemia in Cats?

The increase in creatinine and urea can occur in various situations, so it will also depend on the type of azotemia being treated.

Causes of feline prerenal azotemia

Prerenal azotemia occurs when there is no kidney damage or obstruction of renal flow and develops as a consequence of reduced perfusion of the kidney by a disturbance in blood flow, as they can be:

  • Hypovolemia.
  • Inadequate cardiac output.
  • Prominent vasodilation.
  • Dehydration.

Causes of renal azotemia in cats

Renal azotemia occurs when there is damage to the kidneys themselves. Therefore, azotemia in these cases is caused by:

  • Acute kidney disease: sudden and severe onset with reduced glomerular filtration rate. Sometimes it can be reversible. The most common causes in cats are nephrotoxins (drugs, ethylene glycol, heavy metals, lilies and iodinated contrast agents), hypercalcemia, hypophosphatemia, disorders that cause poor renal perfusion (hypovolemia, thrombosis, infarction, polycythemia or hyperviscosity) or diseases of the renal parenchyma (pyelonephritis, glomerulonephritis, urinary tract obstruction).
  • Chronic kidney disease: progressive reduction in glomerular filtration rate and kidney function, allowing time for compensatory mechanisms to be activated. It is common not to find an original cause in cats, and it can derive from some cause of acute kidney disease such as urinary tract infections, non-steroidal anti-inflammatory drugs or hypovolemia. It can also be caused by hypertension.

Causes of postrenal azotemia in cats

Postrenal azotemia occurs when the flow of urine is blocked by extrarenal causes. Thus, the causes can be:

  • Obstruction of the urethra.
  • Blockage, tear, or ligation in the ureters.
  • Leakage from or rupture of the bladder.

Other causes of azotemia in cats

On the other hand, the high urea in cats no increase in creatinine can occur after eating a food rich in protein when there is intestinal bleeding. High urea and normal creatinine can also be produced in cats when protein catabolism is increased secondary to pyrexia or the use of corticosteroids.

However, the high creatinine in cats It may simply be due to the fact that the cat has a lot of muscle mass, since the more muscle mass it has, the higher the normal concentration of creatinine..

Symptoms of azotemia in cats

Depending on the type of azotemia in cats, the symptoms may be:

Symptoms of feline prerenal azotemia

The symptoms in this case are those related to low perfusion due to alteration of normal blood flow. In these cases, the feline may manifest:

  • Anemia.
  • Pale mucous membranes.
  • Weak pulse.
  • Increased skin fold.
  • Dryness of the mucous membranes.
  • Low hematocrit.
  • Decreased blood pressure.
  • Alterations in heart and respiratory rhythm.

Symptoms of renal azotemia in cats

Renal azotemia by acute kidney disease can produce symptoms such as:

  • Oliguria (reduced volume of urine).
  • Anuria (do not urinate).
  • Back arched from kidney pain.
  • Tachypnea.
  • Arrhythmias.
  • Temperature increase.
  • Depression.
  • Vomiting and / or diarrhea.
  • Normal or enlarged kidneys.

Renal azotemia by chronic kidney disease can produce symptoms such as:

  • Oral ulcers.
  • Halitosis.
  • Dehydration.
  • Chronic disease anemia.
  • Gastrointestinal signs.
  • Polyuria-polydipsia.
  • Kidneys reduced in size.
  • Lack of appetite with weight loss.
  • Vomiting.
  • Acute blindness.

Symptoms of postrenal azotemia

Blocking the flow of urine due to obstruction of the urethra due to stones or mucous plugs in FLUTD (feline lower urinary tract disease), damage to the ureters or ruptured bladder can cause symptoms such as:

  • Dysuria (pain when urinating).
  • Stranguria (painful urination, drip).
  • Pollakiuria (urinating small amounts many times a day).
  • Hematuria (urinating blood).
  • Licking of the urogenital area.
  • Urination out of the sandbox.
  • Hyperkalemia (increased potassium).

Diagnosis of azotemia in cats

To detect azotemia one must extract blood to determine the concentration of urea in serum or plasma. Later it will be necessary to see if this azotemia is prerenal, renal or postrenal.

Diagnosis of prerenal azotemia

The dehydration in cats can be determined by performing the following tests:

  • Skin fold.
  • Check for dry mucous membranes.
  • Check the sinking of the eyeball.
  • Blood tests to check for an increase in hematocrit and total proteins.

A thorough physical examination to detect hypovolemia.

Diagnosis of renal azotemia

In kidney disease, the glomerular filtration rate is reduced and the creatinine concentration it has been considered as an indirect indicator of the glomerular filtration rate. However, SDMA reflects this rate more accurately and diagnoses kidney disease earlier than creatinine, since SDMA increases when at least 25% of kidney function has occurred and creatinine does not increase until this loss it is at least 75%. In addition, it must be considered that creatinine depends on the muscle mass of a cat, which can give false results in a very muscular or very thin cat such as hyperthyroidism, which does not happen with this parameter..

To diagnose the stage of kidney disease, a series of measurements and parameters such as SDMA, creatinine, UPC (urine protein / creatinine ratio) and systolic blood pressure.

A good anamnesis should be taken to know if you have been in contact with a drug or nephrotoxic substance, if there is a urinary tract infection, hypertension or low renal perfusion and determine the phosphorus and calcium concentrations to find the cause of the kidney disease.

A kidney ultrasound to assess its size and shape and see the rest of the structures of the urinary system.

Diagnosis of postrenal azotemia

To diagnose a urethral, ​​ureteral obstruction, or bladder rupture, the following tests should be performed:

  • Blood chemistry to detect azotemia, hyperkalemia, hyperphosphatemia, and metabolic acidosis.
  • Imaging techniques to detect fluid in the abdomen (uroabdomen) and sometimes an obstruction may even be seen. Analysis of the fluid after extraction to see if it is urine.
  • Urinalysis to detect crystals, mucous plugs, or blood.

Treatment of azotemia in cats

Before a prerenal azotemia, what you have to do immediately is replenish fluids and perfusion to the feline, through fluid therapy and sometimes blood transfusion.

In cases of renal azotemia, it is necessary to treat the cause in the disease acute kidney injury, as well as correcting dehydration and electrolyte disturbances. It is important to treat concomitant diseases if any (diabetes, hyperthyroidism, heart disease, tumor). Specific treatment for kidney disease consists of:

  • Treat dehydration with fluid therapy.
  • Treat hypertension with amlodipine.
  • Treat proteinuria with ACE inhibitors, such as benazepril.
  • If hyperphosphatemia, start with a renal feed and after a month if phosphorus is still high give a phosphorus chelator.
  • Appetite stimulants such as mirtazapine.
  • Antiemetics such as maropitant or metoclopramide.
  • If there is a gastric ulcer, omeprazole or ranitidine.
  • If they cannot tolerate food, feeding tube.
  • Diet treatment: reduction of protein, phosphorus, sodium and increase of potassium, fat and B vitamins.
  • If there is anemia with a hematocrit less than 20%, erythropoietin.
  • Antibiotics, if there is a urinary tract infection.

In postrenal azotemia, the feline must be unblocked, damage repaired, urinary stones removed with diet (struvite) or surgery (calcium oxalate), and in cases of bladder rupture, operate on them to restore the damage..

This article is merely informative, at we do not have the power to prescribe veterinary treatments or make any type of diagnosis. We invite you to take your pet to the vet in the event that it presents any type of condition or discomfort.

Leave Your Comment

Please enter your comment!
Please enter your name here