Insufficient Urine Production in Dogs

Oliguria, also related to anuria, is a decrease in the volume of urine produced. The difference between oliguria and anuria is that anuria is used to describe instances where the kidneys do not produce urine, while oliguria simply refers to a decrease in urine production (not necessarily at the fault of the kidneys). Oliguria is most likely related to renal function, as opposed to anuria, which is related to kidney function. Anuria could occur as the result of decreased renal function, though it is usually linked to obstruction of urine outflow or problems in the urinary tract. Symptoms include dehydration, shock, loss of appetite, and heart disease. Treatment varies depending on the underlying cause of the oliguria, but can include IV administration of fluids, medication, or surgery. Prognosis relies largely on the underlying cause of the condition.

Oliguria is a decrease in the body’s urine production, typically linked to problems with renal functionality. It is related to anuria, which is where the kidneys don’t produce urine, typically linked to obstruction or urinary tract problems. 

• Decrease in development of urine
• Dehydration
• Shock
• Heart Disease
• Hypoadrenocorticism (decrease in secretion of adrenocorticotropic hormone, which regulates levels of cortisol in the body)
• Vomiting
• Lethargy
• Loss of appetite
• Weight loss
• Constriction of arteries in the renal area
• Decrease in permeability of the glomerulus (a group of capillaries near the kidneys)
• Obstruction of tubular lumens (inside space of arteries)

Types

• Physiologic oliguria - Physiologic oliguria occurs when the kidneys are saving more water than normal (as opposed to disposal through urination) in order to achieve normal levels of body fluid balance. When physiologic oliguria is the cause, animals will form small volumes of urine with high levels of specific gravity (the ratio of density of the urine to the ratio of a reference substance) and high osmolality (concentration of urine expressed as total of solute particles per kilogram). This is common in animals with prerenal azotemia (increased levels of nitrogen in the blood caused by a lack of blood flow to the kidneys; it is the most common cause of acute renal failure). Prerenal azotemia is typically caused by abnormalities that reduce renal perfusion with blood (e.g., limit blood flow), such as dehydration, shock, and heart disease. If the cause of prerenal azotemia is removed quickly, the kidneys will likely return to normal functionality. However, if the cause remains, primary ischemic renal disease may develop.
• Pathologic oliguria - Pathologic oliguria is when the body does not have enough urine available for the body’s normal excretion of waste (through urination).  The threshold for diagnosing pathologic oliguria is less than 0.5 ml/kg/hr. In dogs who are rehydrated and have acute renal failure, concentrations between 0.5 ml/kg/hr to 1.5 ml/kg/hr are indicative of relative oliguria. If infusion of fluids through IV results in excessive urination, the oliguria likely has a prerenal component. Pathologic oliguria may develop during early stages of renal failure as the result of generalized ischemic (resulting in restriction of blood supply to tissues) or nephrotoxic tubular (death of tubular epithelial cells in rental tubules of the kidneys) disease.

There are a number of different diseases that can cause oliguria in dogs. Some of these diseases include:

• Neoplasms (abnormal growth of tissue), strictures (restrictions) or uroliths (concretion in the urinary tract) that block the urethral lumen
• Herniation of the bladder, partially obstructing the outflow of urine through the urethra or ureters
• Rupture of urinary bladder
• Reduced blood perfusion in the kidney, usually the result of dehydration, heat stress, low blood pressure, trauma, and diabetes mellitus
• Blockage of urethra, which can be caused by urethritis (inflamed urethra), crystalluria (crystals in the urine, causing blockage), transitional cell carcinoma
• Dysfunction of the kidneys, which may be the result of acute renal failure, chronic renal failure, liver disease, trauma, and multiple organ failure

It is important to advise your veterinarian of recent behavioral changes you have seen in your pet, as well as the reasons for your concern that have led you to the visit. Any information you can provide will lead to a quicker diagnosis. Listed below are the tools that may be used in the diagnostic procedure.

• Physical exam
• Kidney palpation
• Urinalysis
• Urine specific gravity
• Urine dipstick
• Urine cytology
• Urine microscopy
• Complete blood tests
• X-ray of urine and liver
• Ultrasound of urine and liver
• Urethrocystoscopy (insertion of small camera, called an endoscope, to evaluate the bladder)

Oliguria and anuria are serious issues and if there are symptoms of these conditions, you should seek veterinarian advice and medical treatment immediately. Treatment varies depending on the underlying cause of the oliguria. Possible treatments your veterinarian may employ include:

• Administration of fluids through an IV
• Urethral catheterisation (drainage and collection of urine from the bladder using a tube, called a catheter)
• In cases where the oliguria is caused by an obstruction or tumor, surgical removal will likely be required
• Medications may be administered to induce diuresis (excessive urination)
• Additional treatment will be completed for symptoms accompanying oliguria and anuria

Post-treatment recovery and management depend largely on the underlying cause of the oliguria. It is important that urination is monitored to ensure that recovery is going smoothly. A catheter may be used through the recovery process to measure the volume in the bladder. Your veterinarian can advise best practices for catheter implementation and additional monitoring.