BGOTW #34

Blood Gas of the Week #34

An 11 year old, spayed female mix breed dog is presented for acute onset anorexia and vomiting. She escaped from the yard yesterday and was missing for about 18 hours before returning home this morning. Her physical examination is unremarkable and her vital signs are all normal. Interpret the blood gas.

Step 1: Evaluate the pH

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This patient has a normal pH. A normal pH can be associated with a mixed acid-base disturbance or with a normal acid-base status.

 

Step 2: Evaluate the metabolic and respiratory components

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Both the bicarbonate and CO2 are both in the normal range. This patient has a normal acid-base status. 

 

What other acid-base associated indicator can we determine from the information available?

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We can also evaluate the anion gap as part of this patient’s assessment. While it would be very uncommon, a patient could have a metabolic alkalosis from significant vomiting in combination with an acidifying process such as ethylene glycol toxicity. The anion gap is calculated:

(Na + K) – (Cl + HCO3)

(152 + 4.1) – (117 + 19.9)

= 19.2

The normal range for AG in the dog is 18-21. So this patient also has a normal anion gap. A reason for this dog’s presenting signs is not apparent in the available data.