I am sorry to hear about your Chow's problem, I know that you must be very concerned. Hopefully, we can get this resolved quickly.
1. This incident could be seriously problematic to your dog because of possible chocolate toxicity. One of the best things you can do in this sort of situation is to make your Chow sick immediately and recover the Brownies that way. If you can do this within the first hour after ingestion then this may be possible. For the sake of speed, I will give you a link on how to do this best: https://www.petplace.com/article/dogs/diseases-conditions-of-dogs/how-to-induce-vomiting-emesis-in-dogs/
{ Also be aware that an ER vet will be able to quickly induce vomiting with prescription drugs }
2. However, if you do not manage to quickly induce vomiting and any serious adverse symptoms occur then you should take your Chow to an ER vet without delay. Adverse symptoms could include marked vomiting and lethargy.
3. But in any case, I should be available online for you for the next four or five hours today so please do not hesitate to get straight back to me if your Chow's condition changes in any way, or indeed if you would like to talk things over with me further.
Regards,
Dr. Scott
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