Why Is My Dog Or Cat’s Blood Sodium to Potassium Ratio Abnormal?

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 Dog And Cat’s Blood Sodium:Potassium Ratio = Na:K Ratio

Veterinarians ask for this data or pencil the calculations in themselves when they are suspicious that your dog might have Addison’s disease (adrenal glands that can no longer produce enough cortisone). Addison’s disease is conceivable but considerably less common in cats. Your pet’s Na+:K+ ratio is calculated from its blood sodium level divided by its blood potassium level (veterinarians like to see that ratio between 27 and 40:1) . Because Addison’s disease can deplete your pet’s  blood sodium level and elevate its blood potassium level, ratios that begin with a number lower than 27 might mean that an  ACTH test  for Addison’s disease is in order.

Reasons Why Your Dog Or Cat’s Na:K ratio might be low:

Sodium and potassium are two of your pet’s blood electrolytes . Not all pets with a low sodium:potassium ratio have Addison’s disease but all of them have a health issue.

Another cause can be a period of sustained diarrhea. The inability to urinate (as in a ruptured urinary bladder or urinary tract blockage) can also lower your pet’s Na:K ratio.

Akita dogs that appear healthy occasionally have low Na:K ratios for reasons that are not understood.

Repeated removal of pooled abdominal or chest fluids at your local animal hospital – as might occur to increase comfort and ease breathing in heart or liver failure can also lower Na:K ratio.

For reasons unknown, whipworm infections are also capable of decreasing Na:K ratios.

The same cautions I gave about laboratory-produced false laboratory reading for sodium and potassium apply to your pet’s Na:K ratio as well. The same causes I gave for low blood sodium or high blood potassium will drive down the Na:K ratio. The reverse is also true.

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