High Levels of Blood Nitrogen in Dogs

By PetMD Editorial on Apr. 15, 2010

Azotemia and Uremia in Dogs

Azotemia is defined as an excess level of nitrogen-based substances compounds such as urea, creatinine, and other body waste compounds in the blood.

Azotemia is defined as an excess level of nitrogen-based substances compounds such as urea, creatinine, and other body waste compounds in the blood. It can be caused by higher than normal production of nitrogen-containing substances (with high protein diet or gastrointestinal bleeding), improper filtration in the kidneys (kidney disease), or reabsorption of urine back to bloodstream.

Uremia, meanwhile, also leads to an accumulation of waste products in the blood, but is due to improper excretion of the waste products through the urine because of abnormal kidney function.

Symptoms and Types

  • Weakness
  • Fatigue
  • Vomiting
  • Diarrhea
  • Depression
  • Dehydration
  • Constipation
  • Weight loss (cachexia)
  • Loss of appetite (anorexia)
  • Bad breath (halitosis)
  • Muscle wasting
  • Hypothermia
  • Poor haircoat
  • Unnatural lack of color in the skin
  • A minute red or purple spot on the surface of the skin as the result of tiny hemorrhages of blood vessels in the skin (petechiae)
  • The escape of blood from ruptured blood vessels into the surrounding tissue to form a purple or black-and-blue spot on the skin (ecchymoses)


  • Low blood volume or blood pressure
  • Infections
  • Fever
  • Trauma (e.g., burns)
  • Corticosteroid toxicity
  • High protein diet
  • Gastrointestinal bleeding
  • Acute or chronic kidney disease
  • Urinary obstruction


You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms, to your veterinarian. He or she will then perform a complete physical examination, as well as a biochemistry profile, urinalysis, and complete blood count (CBC). The CBC results may confirm nonregenerative anemia, which is common in dogs with chronic kidney disease and failure. Hemoconcentration may also occur in some dogs with azotemia, whereby the blood thickens due to a decrease of fluid content.

Along with identifying abnormally high concentrations of urea, creatinine, and other nitrogen-based compounds in the blood, a biochemistry test may reveal high levels of potassium in the blood (hyperkalemia). The urinalysis, meanwhile, may reveal changes in urine specific gravity (a urinalysis parameter commonly used in the evaluation of kidney function) and abnormally high concentrations of protein in the urine.

Abdominal X-rays and ultrasound are two other valuable tools often used by veterinarians to diagnose azotemia and uremia. They can help in determining the presence of urinary obstructions and the size and structure of the kidneys -- smaller kidneys are commonly found in dogs with chronic kidney disease, while larger kidneys are associated with acute kidney failure or obstruction.

In some dogs, a kidney tissue sample will be collected to confirm the diagnosis of kidney disease and also to eliminate the possibility of other acute or chronic kidney diseases that may be present.



The type of treatment recommended by your veterinarian will depend on the underlying cause of the diseases, though the ultimate goal is to halt the primary disease, whether it be azotemia or uremia. In the case of urinary obstruction(s), for example, your veterinarian will try to relieve the obstruction to allow normal passage of urine. In addition, if the dog is dehydrated, intravenous fluids will be administered to stabilize the animal and rectify electrolyte deficits.

Living and Management

The overall prognosis of this disease depends on the level of kidney damage, acute or chronic states of kidney disease, and treatment.  However, as most drugs are excreted through kidneys, dogs with kidney disease or failure require extra care for selection of proper medications to avoid further damage to kidneys. Don’t give any drug to your dog without prior consultation with your veterinarian. Moreover, don’t change the brand or dose of the drug prescribed by your veterinarian without prior consultation.

You’ll need to monitor the urine output of your dog at home and in some patients the owners need to properly record the urine output. This record of urine output will help your veterinarian to determine the progression of the disease and overall performance of kidneys with current therapy. Your veterinarian may repeat the laboratory tests to measure the level urea and creatinine concentrations 24 hours after starting intravenous fluids.

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