I am sorry to hear that your pup may have ingested 25mgs of Metoprolol.
It is used in dogs to control arrhythmias, especially supraventricular tacchycardias.
The usual appropriate dose is 0.2mg to 0.4mg per kilogram of body weight. At 15 pounds she is 6.8kg, (15lbs /2.2 lbs per kg = 6.8kgs) so an appropriate dose is 1.36mg to 2.72mg, but we can go as high as 1mg per kilogram of body weight or 6.8mg. He ate roughly 4 times a normal high dose, so we do need to be concerned.
Since it was eaten long enough ago that his heart rate has decreased to 60 beats per minutes that means the drug is fully absorbed and it is too late to induce vomiting.
You have the option of admitting him to an emergency clinic for observation and possible treatment if his blood pressure and heart rate fall too low or watching him at home.
If you choose to take a watch and see approach, since you aren't sure he ate the pill, things to watch for are weakness, and severe lethargy. We will sometimes see diarrhea with this class of drugs too.
If you see any symptoms then an emergency clinic visit is best.
Keep Cody away from stairs in case he gets light headed.
Do you have any more questions for me now?