A dog has been treated with the $\beta$-blocking drug atenolol for the past 6 months. The dog's owners go on a 1 week vacation with their pet, but they forgot to pack the medication. While out one morning, a bee stings the dog on the neck and his breathing becomes labored. Why would using epinephrine (EpiPen) to address anaphylaxis be potentially dangerous in this scenario?

Question

Quizplus · Accepted Answer

Adrenergic receptors, specifically β-adrenergic receptors, are upregulated (increased in number) in response to chronic blockade by β-blockers like atenolol. When the dog is not receiving its medication, these upregulated receptors can become overly sensitive to adrenergic agonists like epinephrine. Administering epinephrine in this situation could lead to an exaggerated response, potentially causing dangerous cardiovascular effects.

A Dog Has Been Treated with The β\betaβ -Blocking Drug Atenolol for the Past 6 Months

A Dog Has Been Treated with The $\beta$ -Blocking Drug Atenolol for the Past 6 Months