My 65 lb Lab/Husky mix has just eaten chocolate fudge brownie, a large piece. About 3 inches square. He doesn’t seem to be in trouble now, but I’m concerned. Since this is not just chocolate, but mixed in the cake format, and he just had a full meal about an hour ago, what can I expect?
We have to hide food from him because people food is more interesting. We do NOT feed him table scraps.
Call a vet and see what they say, better safe then sorry. Welcome to the boards btw, I hope your dog is ok. You probably should read the forum descriptions and various informative topics about board culture before really getting into posting. 
I second that. If you are worried, check with a vet. Most emergency vets (at least around here) are willing to talk to you on the phone before you come in, so you may be able to save yourself a trip. Don’t panic, though – one brownie in a large dog isn’t all that likely to be fatal. The biggest danger is either a small dog or a large dose or both. Baker’s chocolate and dark chocolate are extreme big no no’s. (By “baker’s chocolate,” I do not mean one brownie.)
I think you’ll find better answers to this in our question-and-answer forum, General Questions. I’ll move it there for you.
I am not a vet, but one brownie in a 65-pound dog should be harmless. I wouldn’t even expect diarrhea. Size is definitely on his side.
From this page, your 65-pound dog would have to eat about three pounds of brownies (assuming they were made with semi-sweet chocolate, and that half of the brownies’ weight was chocolate)
If he’d eaten a half-pound package of baker’s chocolate, then you’d need to be worried and on the way to the vet.
Welcome to the Board!
As others have said, if the dog exhibits any strange symptoms, you should get him to the vet, but I’m betting he will be fine. My dog is about the same size and once ate an entire bag of Hershey’s Kisses (including the wrappers.)
What to watch for: (all of these symptoms are always a red flag)
–Vomiting. A puke every now and then is normal, but if the dog vomits repeatedly over a long period of time, you may be in trouble.
–Lethargy. If the dog just wants to lay in one place and pant in lieu of playing or other usual activities, chances are, something’s wrong.
–Diarrhea. Same with puking-- every once in a while is normal, but if his bowels are loose for more than 24 hours, hie thee to the vet.
–Ignoring food.
–High fever.
–Blood in stool or vomit.
–Difficulty urinating.
I’ve heard (sorry, no cite, feel free to disprove me or back me up) that dogs are about 5 times more sensitive to theobromine than humans, so a reasonable estimation would be:
65lbs lab - 1 brownie = 1/65th of a brownie per lbs of body weight of dog
- multiply by 5 to get human equivalent
5/65th of a brownie per lbs, so for a 140lbs woman equivalent you get just under 11 brownies. Doesn’t seem like 11 brownies would kill a grown woman, so you should be fine, but just check with the vet.
Now googling around for a cite I found that canine LD50 for theobromine is 100mg-200mg per kg of body weight. About 350mg/kg for rats. Can’t find an approximate for humans anywhere.
The Straight Dope on Is chocolate toxic to dogs?
I had a dog eat a 1 pound hearsheys kiss, he was probably 10-15 #'s at the time. not only did he not die the little shit ran around like a friggin lunatic for HOURS.
I miss that hersheys kiss 
your husky is fine but a call to the vet would probably do more for your peace of mind than my post will.
Has there been any cases of humans that are hpersensitive to chocolate or theobromine ? Is there an equivalent to theobromine , that are toxic to people?
Theobromine IS toxic to people just not as much as dogs, but it just so happens that even with bakers chocolate you are not liable to eat enough to kill you based on body weight and sensitivity. For the life of me I can’t find any estimated LD50 for humans, but based on my uncited 5x figure somewhere in 1g/kg of body weight would be a good guess. Based on that a 150lbs human will have to eat roughly 24 pounds of bakers chocolate to reach LD50.
Just for reference you can die from ingesting 8-10g of caffeine easily, which is just 40-50 extra strength no-doz pills.
Also another thing is that dogs are capable of eating a lot and will eat a lot if given the opportunity. My 7 lbs chihuahua can probably eat half a pound of food or more (if provided) in one sitting, sometimes more. If a dog gets into chocolate and eats 1/10th its body weight, it’s not even that chocolate is particularly toxic to dogs, it’s that the dog ate 1/10th its body weight. I think if I ate 1/10th my body weight in chocolate in one sitting I’d die too. In fact, even disregarding the physiological impossibility of me eating that much food, I would venture a guess that a lot of things that are completely harmless in normal portion sizes will reach toxic amounts fairly quickly. Definitely things like coffee, alcohol, candy, certain fruits/nuts, honey, etc.