Why Is My Dog Or Cat’s Blood Potassium Level High Or Low?

Why Is My Dog Or Cat’s Blood Potassium Level High Or Low?

Ron Hines DVM PhD

To see what normal blood and urine values are, go here

For an explanation of causes of most abnormal blood and urine tests, go here

To see how tests are grouped, go here

Your Pet’s Blood Potassium Level (K+) In Your Dog And Cat’s Blood

Blood potassium too low = Hypokalemia – Too high = Hyperkalemia 

Dissolved potassium (K+, a positive ion or “cation”) is an important constituent in all the cells of your cat or dog’s body. Potassium is also one of your pet’s important blood electrolytes .  Although much less potassium as an electrolyte is found  free in your pet’s blood than it is in its cells, that small amount of free blood potassium is critical for proper nerve, brain and heart function.

The amount of potassium in your dog or cat ‘s body is controlled by your pet’s kidneys. When potassium is in the body in excess, the kidneys excrete it into the urine to eliminate it from the body. When body potassium stores are low, the kidneys conserve  potassium. (ref)

So kidney problems of any kind in your dog or cat often lead to abnormal amounts of potassium in their blood stream (both lower levels and higher levels) . 

Health issues that make your pet’s body more acidic (=metabolic acidosis) will also shift potassium from your pet’s cells into its blood stream.

Your dog and cat’s blood platelets (aka thrombocytes) also contain large amounts of potassium. So health problems that cause abnormal blood clotting and platelet destruction will also elevate your cat and dog’s blood potassium level.

Blood potassium level must remain within very strict limits, if not, many metabolic systems will stop functioning correctly. When blood potassium is too low (hypokalemia), muscle weakness and impaired (decreased) kidney function can result. 

A complicating diagnostic problem for your veterinarian is that both higher-than-normal potassium and lower-than-normal blood potassium can show similar symptoms in your pet. 

Both abnormally low and abnormally high blood potassium levels interfere with normal heart beat (arrhythmia). When K+ levels are abnormally high, heart rates can become abnormally slow (bradycardia) and can even cease (cardiac arrest). The other possible signs of excessive blood potassium levels (hyperkalemia) are poorly described in dogs and cats. In humans, those signs include muscle weakness and fatigue as well as cardiac arrhythmia due to  AV block

Reasons Why Your Pet’s Potassium Levels Might Be Low (Hypokalemia):

The most common reason for low blood potassium level in your cat or in your dog is failing kidneys (=chronic renal failure or CRF). These are the pets that drink larger than normal amounts of water and produce large amounts of dilute urine  that carries away potassium. Kidney failure is one of the most common health problems we veterinarians see in older pets.

Blood potassium level can also drop when the kidney’s urine flow that has been obstructed by things such as kidney or bladder stones – is suddenly relieved through surgery or manipulation. In those cases, the cat or dog’s kidneys temporarily produce excessive amounts of urine (diuresis) as its body cleanses itself of the wastes that accumulated in their blood stream during the period of obstructed urine flow.

Hypokalemia (low blood potassium) can also occur in dogs and in cats that experience chronic diarrhea such as dog with with dogs with IBD or cats with IBD /or vomiting. Persistent diarrhea and/or vomiting due to dietary indiscretions can have a similar potassium-lowering effect. 

Low blood potassium occasionally occurs when fluid accumulates in your pet’s abdomen due to peritonitis, pancreatitis or the pooled fluids [ascites] that accumulate due to heart or liver failure.

The drugs used to decrease those fluids (eg furosemide/Lasix® diuretic) can lower your pet’s blood potassium levels as well (a “potassium wasting” effect”) – probably because they encourage large amounts of potassium-containing urine to be produced. 

Some cats are prone to muscle disease (myopathy) and a few special cat breeds to muscle inflammation (eg hypokalemia in Burmese cats (ref), and myopathies in Sphinx cats). Those problem are often accompanied by lower blood potassium levels.

A lack of a dietary source of sufficient potassium when your dog and cat will not eat could conceivably cause hypokalemia – but in reality it rarely does. 

Blood potassium levels go down slightly as the body becomes less acidic (metabolic alkalosis, high blood pH). That can occur due to persistent vomiting or after periods of rapid respiration (panting).

Uncontrolled diabetes in dogs and in cats, insulin injection overdose, adrenaline release due to stress, bacterial endotoxemias and high doses of corticosteroid medications have all been associated with hypokalemia.

Pets given large amounts of IV fluids that contain no potassium (in emergency situations) or when the fluids contain large amounts of bicarbonate buffer to meet other urgent needs (such as acidosis), can cause your pet’s blood potassium level to drop.

Fatty/ lipemic blood specimens can give incorrectly low potassium reading on some blood analyzer machines (=pseudohypokalemia).

Reasons Why Your Pet’s Potassium Levels Might Be High (Hyperkalemia) :

Dogs and cats with acute (sudden) onset of kidney failure that includes kidney swelling and shut down (oliguric renal failure) no longer have the ability to produce sufficient urine (anuric kidney disease) to remove excess potassium from their bodies. In those cases, hyperkalemia usually develops.

Antifreeze poisoning , aminoglycocide antibiotics like gentamycin and amikacin as well as trimethoprim-containing antibiotics, digoxin given for heart disease, ACE inhibitors like enalapril given for heart problems and even leptospirosis infection can all be responsible for higher than normal blood potassium levels. That effect on potassium blood levels is primarily due to the damage these medications and diseases can cause to your dog and cat’s kidneys. Your veterinarian is going to be alerted to those issues through changes in your pet’s BUN and Creatinine levels – not its elevated blood potassium reading. 

The same situation occurs with urinary tract stones when your pet’s kidneys are prevented from flushing excess potassium out of its blood stream. Feline urological syndrome (FUS), and other problems that interfere with your dog or cat’s normal urine flow will have a similar effect. So will any tears in its bladder, or ureters which leak urine into the pet’s abdomen. Accidents involving cars are the most common cause of that.

Pets (usually dogs) whose adrenal glands no longer produce sufficient aldosterone hormone (as in Addison’s disease and perhaps whipworm infection = pseudoaddisons disease) often have higher than normal blood potassium levels.

Many chronic health problems can lead to a body that is too acidic (metabolic acidosis). All of them can raise your pet’s blood potassium levels. They include uncontrolled diabetes (=diabetic ketoacidosis  in dogsin cats) , starvation, shock and all the things that cause low blood pH, low blood bicarbonate or C02 levels and a high anion gap.

High potassium reading can be false (an artifact) when they are run on a blood sample that had partially clotted, hemolyzed or sat too long before being analyzed.

Akitas, (and perhaps other Japanese dog breeds), have naturally higher levels of potassium in there red blood cells. That make their blood potassium readings harder to interpret (pseudohyperkalemia).

Not centrifuging your cat or dog’s blood and separating off the serum for analysis soon enough will always make the potassium reading a bit higher. Elevated WBC counts  and elevated reticulocyte counts can raise blood potassium levels as well.

Because most of your pet’s potassium resides in the cells of its tissue, not in its blood, just about any crisis that causes sudden wide spread tissue destruction can cause a sudden increase in blood potassium level too. Those can be traumatic, infectious, cancerous or obstructions to circulation.

Complementary Tests:

Because changes in blood potassium levels have so many possible causes, follow up tests are too numerous for me to list. But your veterinarian might begin with: CBC/WBC and blood chemistry values , urinalysis, sodium:potassium ratio ,  ACTH  stimulation test (if Addison’s disease is suspected), electrocardiogram ( ECG)


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