Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry to hear about Benito eating some milk chocolate.
A 24 pound pup would need to eat 3.6 ounces of milk chocolate to see symptoms of drooling, nausea, vomiting and diarrhea and almost 7.2 ounces of milk chocolate to see hyper-excitability and an elevated heart rate.
At higher amounts we can see muscle tremors and possible seizures.
Since your pup only ingested 2 ounces it is very unlikely that Benito will have any symptoms of toxicity.
As an extra precaution I would encourage you to get him to drink as much as possible and to get him out to urinate frequently. Chocolate toxins are metabolized out through the kidneys and can be reabsorbed from the bladder so we don't want them to sit in his bladder for long.
In most cases mild chocolate toxicity is out of their system in 24 to 48 hours. We generally begin to see symptoms, if they eat a toxic amount, within 4 to 6 hours.
If he seems at all nauseous to try and settle his stomach you can give either:
1) Pepcid ac (famotidine) at a dose of one 10mg tablet every 12 hours
2) Prilosec (omeprazole) at a dose of one half of a 20mg tablet every 24 hours
These are acid reducers and should help him feel less nauseous. They are quite safe and can be used for several days if needed.
Then you can feed him a bland diet for the next couple of days. A homemade bland diet is a mix of 1/3 boiled minced white skinless chicken or lean boiled hamburger and 2/3 boiled white rice mixed with some low salt chicken broth to make it easy to lap up and swallow. Feed small meals frequently.
If you do notice a very rapid heart rate (more than 160 beats per minute in a small dog) repetitive tremors or seizures then he should be seen by a veterinarian on an emergency basis for treatment. They can use injectable medications to control his heart rate and stop the seizures until the toxic levels fall.
But honestly with the amount he ate and his weight I think that he won't have any symptoms, and you won't beed to do anything at all.
Best of luck with Benito, let me know if you have any further questions.