First, I am very glad to hear it is free from that dangerous artificial sugar and that it sounds like she hasn't had much. Still, since it has cocoa powder (which is quite potent) and its the third ingredient (which means there is quite a bit in it), we would be best to err on the side of caution for Cali. The reason is because even low dose chocolate ingestion can cause GI upset (vomiting, diarrhea, appetite loss) in the first 4 hours post ingestion; but if she did get quite a bit of cocoa powder then we could see more severe signs (ie breathing and heart rate changes, tremors, and possible seizures).
Therefore, in this case and since she has been caught in the act, we can induce vomiting now. To induce vomiting at home, you can administer 3% hydrogen peroxide orally at a dose of 1ml per pound. (2 teaspoons per 10 pounds of body weight). You can give it via dropper, syringe, turkey baster – we just want to get it in. After giving this orally, move the abdomen around or get your wee one walking about to get things mixing. This should usually lead to vomiting. If it is unsuccessful after 10 minutes then it can be repeated twice more. And if we still have no vomiting, then you'd need to consider seeing your local vet (or ER vet) so that apomorphine (a very strong injectable emetic) can be administered just get this out of the stomach and avoid any adverse issues.
As well or alternatively, you can also consider administering activated charcoal at this stage. This is available over the counter from the pharmacy (ask for the high strength version, not the one for gas) and works by binding any theobromine (the chocolate toxin) in the stomach. For activated charcoal, we tend to give 1-4 grams per pound every 8 hrs. This can be mixed with food to be fed or with water to syringe feed (do note that it stains, so keep it away from white carpets/clothes). This will just limit how much she can absorb and reduce the intoxication risk for Cali.
Finally, after the above, we do want to try to address any potential GI upset here for the next 24-48 hours. To do so, you can consider offering a light diet option for a few days. Examples of an easily digestible diet include cooked white rice with boiled chicken, boiled white fish, scrambled egg, or meat baby food (as long as its free from garlic or onion powder). Ideally, we want to offer this as small frequent meals to keep the stomach settled. Further to this, if we see any signs of nausea, then we can also treat with an antacid. There are a number of antacids that are available over the counter and pet friendly. Ones we can use here include Pepcid (More Info/Dose @http://www.petplace.com/article/drug-library/library/over-the-counter/famotidine-pepcid) or Zantac (More Info/Dose @ http://www.petplace.com/article/drug-library/library/over-the-counter/ranitidine-hcl-zantac). Whichever you use, we'd give this 20 minutes before food to allow absorption and of course double check with your vet before use if your wee one has any known health issues or is on any medications you haven't mentioned.
In this situation, this doesn't sound like a high dose ingestion but we would be concerned about possible adverse sign with this having a lot of cocoa powder in it. Therefore, we can try the above to offset that here for Cali. Of course, if you are struggling with the above or she does show those signs I noted, then we'd need to consider possibly having the local ER vet take the above steps for you +/- symptomatic care to offset any risk for her.
Please take care,
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