Potassium poisoning, or hyperkalaemia, is an excess of circulating potassium in the body. Hyperkalaemia is a relatively common electrolyte abnormality encountered by vets. And it is considered an emergency due to the effect it can have on the patient, and the severity of symptoms. 

Table of contents

What is the role of potassium in the body?

Potassium is a mineral and an electrolyte present in all body tissues. It is important in cell function, regulating nerve transmission and muscle contraction and is especially important in controlling the heart’s electrical function. 

Potassium works alongside sodium to maintain the fluid balance inside cells and the electrochemical gradient across the cell membrane. A specialised sodium-potassium pump in the cell membrane works to maintain the balance of these two electrolytes. For every three sodium ions pumped out of the cell, two potassium ions are pumped in. This means that normally, there is a higher sodium concentration outside the cell than inside, and vice versa for potassium. In hyperkalaemia, this concentration gradient reverses. This results in a higher potassium concentration outside the cell; which can lead to problems associated with nerve transmission, muscle contraction and kidney function. 

If that was complicated, think about it this way: each cell is constantly pumping potassium in and sodium out. This is essential for muscles to contract and nerves to fire. But if the potassium levels outside the cell are too high, it can interfere with normal muscle, heart and nerve function.

Where does potassium come from?

Potassium is absorbed primarily in the small intestine from potassium rich foods. Approximately 90% of the potassium consumed is absorbed and used to maintain the sodium-potassium gradient across the cell membrane. The remaining 10% is excreted primarily via the kidneys in the urine, helped by specific hormones produced by the body. The kidneys play a vital role in maintaining body potassium levels by increasing or decreasing the amount excreted depending on the amount of potassium consumed. 

Foods rich in potassium that our pets may consume include meat, fish, dairy products, potatoes and certain vegetables. Pet foods labelled as ‘complete’ must provide all the energy and essential nutrients needed for the target species, including potassium. This means further supplementation shouldn’t be necessary. 

Why is potassium poisoning important?

Hyperkalaemia leads to clinical signs associated with muscle, nerve and heart function which include weakness, collapse, flaccid (floppy) paralysis and heart rate abnormalities. These symptoms occur due to the disruption of the electrochemical gradient across the cell membrane. Without treatment, this condition can become rapidly fatal. 

What causes potassium poisoning?

The most common causes of hyperkalaemia seen by vets include reduced excretion of potassium via the kidneys, hormone abnormalities and conditions causing redistribution of potassium within cells.

Reduced excretion of potassium 

This usually occurs due to kidney and urinary tract disorders in companion animals. And it is commonly encountered in cats with Feline Lower Urinary Tract Disorder (FLUTD). FLUTD is a term used to describe a range of conditions affecting the bladder and urethra of cats; including urinary stones (uroliths), urethral plugs, bladder infections and stress-induced inflammation or Feline Idiopathic Cystitis (FIC). These can often lead to hyperkalaemia because they cause a blocked bladder, preventing urination and thus potassium excretion. 

Male cats are more at risk of a urethral obstruction and therefore hyperkalaemia due to their longer narrower urethra compared to female cats. Reducing the risk of FIC involves minimising stress, keeping cats at a healthy body weight, allowing outdoor access where appropriate and providing cats with a good quality mix of wet and dry food. Each cat responds differently to their environment. Identifying an individual cat’s potential causes of stress is vital and is something your vet can advise you on. Symptoms of FLUTD include repeated attempts to pass urine, straining in the litter tray, vocalising while urinating, urinating in strange locations, blood in the urine and licking at the genitals. Once the inciting cause if identified, FLUTD can generally be managed to prevent more serious complications such as potassium poisoning. 

Addison’s Disease

Another relatively common cause of hyperkalaemia seen by vets in practice is Addison’s Disease, or hypoadrenocorticism. This condition results in reduced hormone production from the adrenal glands; two specialised glands located near the kidneys that produce cortisol, the stress hormone, and aldosterone, which helps to regulate the body’s sodium and potassium levels by controlling excretion in the kidneys. Addison’s disease is primarily caused by immune mediated destruction of the adrenal glands and causes vague, non-specific symptoms such as vomiting and or diarrhoea, lethargy, unexplained weight loss and increased drinking and urinating. Certain breeds predisposed to Addison’s Disease include Labrador Retrievers, Standard Poodles, Great Danes and Nova Scotia Duck Tolling Retrievers. 

Again, with appropriate and prompt treatment Addison’s Disease can generally be managed, allowing the affected animal to lead a largely normal life. 

GDV

We also see dangerously high potassium levels in dogs with a Gastric Dilation and Volvulus (GDV or bloat). This occurs because of tissue devitalisation (loss of blood supply as the stomach twists, leading to cell death), resulting in leakage of potassium into the bloodstream. In many cases, it can prove fatal, and is one of the major reasons why GDV dogs are so difficult and dangerous to anaesthetise unless stabilised first.

If you suspect your dog may have a GDV, with signs like unproductive retching or swelling of the abdomen with pain or restlessness, you should contact your vet immediately as an emergency.

How is potassium poisoning treated?

Because of its effects on the body, hyperkalaemia is considered a medical emergency and early intervention is essential to achieve a favourable outcome.

Treatment depends on the initial cause but often includes intravenous fluid therapy, which aims to dilute potassium concentrations and shift potassium from outside to inside cells, drugs to protect the heart muscle and in the case of Addison’s Disease, hormone replacement therapy. In cats with a urethral blockage, decompression of the bladder and placement of a urethral catheter is important to clear the blockage and allow the animal to pass urine.

Once potassium levels have been restored to normal and the inciting cause identified, a full recovery is generally expected. 

Summary 

Potassium is a mineral and electrolyte vital in maintaining various bodily functions in both humans and animals, and is absorbed from potassium rich foods such as meat, dairy, potatoes and certain vegetables. Excretion of potassium occurs primarily in the kidney and problems can arise when this excretion is prevented, leading to potassium poisoning, or hyperkalaemia. 

Potassium poisoning is a serious and potentially life threatening condition which can be brought on by a variety of initial causes. With prompt and appropriate veterinary input, it can generally be treated and the inciting cause managed. 

It is important to contact your vet if you notice any changes in your pets behaviour or demeanour. The earlier you seek advice, the better the outcome is likely to be. 

References and further reading