A 3 year old, spayed female cat is presented by the elderly owner’s caregiver. She informs you she has minimal knowledge of the cat but that the owner thinks the cat is not eating well, and might been have vomited in the last few days. As part of your diagnostic evaluation you obtain blood work. Interpret the blood gas:
Alkalemia can be caused by a high bicarbonate or a low carbon dioxide. In this case the bicarbonate is high and carbon dioxide is low. Since both the high bicarbonate and the low carbon dioxide are alkalinizing processes, both processes are contributing to the high pH – this is a mixed acid-base status characterized by both metabolic and respiratory alkalosis.
We need to think about things that can cause metabolic alkalosis and respiratory alkalosis.
So let’s tackle metabolic alkalosis first: specifically, this is a hypochloremic metabolic alkalosis which in veterinary medicine leaves us with two primary differentials:
Vomiting (probably many times to create the alkalosis), possibly with pyloric or high duodenal obstruction
Loop diuretics
For the respiratory alkalosis the list is a little bit vague – really anything that might make the cat hyperventilate:
Hypoxia
CNS disease
Pain
Fear
Anxiety
Nausea
etc
Clearly some additional history and information about the physical examination findings are needed to help drive the next steps in this patient’s diagnostic evaluation.
