Hemodialysis at CASE

April 28, 2021

Hemodialysis is a therapeutic option utilized more frequently in veterinary medicine to support animals in kidney failure and in some toxicities.  This article will briefly describe normal kidney function, kidney disease and provide introductory information about hemodialysis.

The Role of Normal Kidneys

The kidneys provide a vital role in producing urine, eliminating toxins, regulating electrolytes, maintaining fluid balance and controlling blood pressure.  To do their job efficiently, the kidneys receive enough blood to filter 100% of the total blood volume every 5 minutes.  Fortunately, the kidneys have an incredible regenerative ability and additional functional reserve.  In fact, most people and animals won’t show any abnormalities with only 15-20% of normal kidney function.

Acute Kidney Injury

Some conditions may abruptly alter kidney function.  These may include severe bacterial infection, leptospirosis, anti-freeze toxicity, medication overdose, obstructive urinary stones, or heatstroke amongst other less common possibilities.  Initial treatment may utilize IV fluids, antibiotics, fluid management medications and agents to increase blood flow to the kidneys.  In many instances, these techniques are effective but some animals may benefit from hemodialysis to temporarily filter blood toxins in order to feel better faster, improve their chance of recovery and reduce the risk of complication.  The goal of treating acute kidney disease is to return to normal or near-normal kidney function allowing animals to experience an exceptional quality of life without long-term treatment. Acute kidney failure is the most common use for hemodialysis in veterinary medicine and depending on the underlying cause, can be associated with an excellent prognosis.  Some conditions may only require 2-4 dialysis sessions before recovery occurs.

Chronic Kidney Disease

Chronic kidney disease is one of the most common conditions we are faced with in veterinary medicine today, particularly in cats.  As with acute kidney injury, there are a number of different forms of chronic kidney disease.  Most animals with chronic kidney disease respond favorably to subcutaneous fluids, blood pressure medication, intestinal antacids, dietary management and over-the-counter supplements.  Unfortunately over time, kidney disease may slowly progress.  When this occurs, hemodialysis can replace kidney function allowing for an excellent quality of life.  Since the kidneys are less likely to regain function, most animals with chronic disease will require outpatient dialysis 2-3 times per week in order to replace what the kidneys were doing 24/7.  This exemplifies how efficient dialysis can be and many owners may appreciate an improvement in quality of life as compared to traditional management. Chronic kidney disease is the most common use for dialysis in human medicine and occasionally pursued in veterinary medicine.

What is hemodialysis?

Hemodialysis is a method of filtering blood useful in replacing kidney function.  Hemodialysis is extremely effective in patients with very elevated kidney values, electrolyte abnormalities or those who have stopped forming urine, particularly when these abnormalities persist despite initial medical therapies.

How does hemodialysis work?

A hemodialysis machine is composed of three main parts:  pump, filter and computer.  The pump keeps blood moving through a thin line from the patient, to the filter, and back to the patient.  The filter is a cylindrical “artificial kidney” containing hundreds of tiny porous tubes, which sit within a fluid bath called dialysate. As blood flows through the tubes, toxins cross from the blood into the dialysate bath, which is then discarded.  Blood and protein are retained within the tubes and returned to the patient. In this way, blood stays within the lines and never actually enters the dialysis machine.  The computer calculates how much fluid and toxin is removed and generates new dialysate to ensure normal electrolytes and patient safety.

When is hemodialysis used?

Hemodialysis is most commonly utilized to support patients in times of kidney failure but can also be used to filter recently ingested toxins.  Some things that can be removed from the blood include antifreeze (and it’s toxic metabolites), non-steroidal anti-inflammatory medications such as aspirin and ibuprofen, phenobarbital, Tylenol, and anti-depressants amongst others. Removing these substances reduces the risk of complication and allows for earlier hospital discharge.

How is hemodialysis performed?

To perform dialysis, a unique IV catheter is placed beneath a neck bandage.  Blood is removed using this catheter and passed through the filter allowing for cleaned blood to return to the patient. Since most of the treatment occurs away from the patient, pets can rest on a comfortable bed during a session and commonly fall asleep.  Each hemodialysis session generally lasts 4-6 hours.  We monitor things such as blood pressure, heart rate, blood values and computer variables calculated by the hemodialysis machine.

How do Animals Feel with Hemodialysis?

Many animals with kidney failure feel very sick resulting in lethargy, weakness, vomiting, and poor appetite. These signs are attributed to accumulation of toxins, which are normally eliminated by the kidneys.  Since dialysis clears these substances from the blood, most animals feel much more alert and energetic after one or two dialysis sessions. In fact, animals undergoing chronic dialysis may start associating the dialysis room with a sense of euphoria since they know they always leave the room feeling better.

Who Offers Hemodialysis?

Once a rarity, the number of veterinary dialysis centers are increasing across the country.  CARE is the only provider of hemodialysis, continuous renal replacement therapy, and apheresis within this region of the United States. Combined, Drs. Heffner, Gordon, and Monaghan have  more than 20 years in combined experience delivering hemodialysis. 

How do I learn more about hemodialysis?

Please schedule an appointment with the nephrology service at CASE. Drs. Heffner, Gordon, and Monaghan are happy to review your pet’s case, explore any and all options available, and help you determine which route is the best for you, your family and your beloved pet.