If your dog ate chocolate he's in danger of some serious, potentially fatal, consequences.
This is because chocolate contains Theobromine, one of a group of natural stimulants called Methylxanthines (caffeine is another common Methylxanthine).
These affect your dog's central nervous system and his heart.
They cause the heart beat faster and/or erratically, and also dilate blood vessels which makes blood flow faster, while at at the same time lowering blood pressure.
They also acts as a diuretic - forcing the kidneys to work harder and output more urine.
When dogs ingest chocolate, they metabolize the Methylzanthines it contains very slowly (so it stays in their bodies for longer and can build up to toxic levels quite easily).
Symptoms of poisoning in dogs can show up almost right away, but they can also take 12 - 24 hours to develop.
They can sometimes last last for up to 48 hours or more.
Although symptoms of chocolate poisoning in dogs can take a while to develop, it doesn't take much to make them very sick indeed.
For a small dog, ingesting even a tiny amount can be deadly.
Coffee, coca-cola (and to a slightly lesser extent, black tea) contain caffeine which is an even stronger Methylzanthine and is also highly dangerous and toxic to dogs.
It's important to know how much is too much and how your dog's weight, age and health fits into the equation.
This is a good question, but unfortunately there is no 'one-size-fits-all' answer because different types of chocolate contain differing concentrations of Theobromine.
The darker the chocolate, the more dangerous it is to your pet.
Baking chocolate contains the highest levels of Methylzanthine - approx. 400mg per ounce in fact.
Semi-sweet chocolate has about 260mg per ounce, and milk chocolate about 45mg per ounce.
White chocolate has the least Theobromine, somewhere around 1mg per ounce.
Most chocolate candies will contain anywhere between 40mg and 60mg of Theobromine per ounce.
Chocolate-flavored frosting and such generally has even lower levels as they're also made up of sugar, butter and so on.
Cocoa powder also contains Theobromine, so do cocoa beans.
For dogs, how much Theobromine is TOO much isn't an exact science, and eating one ounce of milk chocolate doesn't carry the same risks as eating an ounce of bakers chocolate.
A dog who ate chocolate may have ingested enough Theobromine to be life-threatening.... or it could be that the worst he's going to suffer is some diarrhea and vomiting.... what happens depends on both the type he ate, and his size/weight.
If your dog ate chocolate, here's a quick guide that gives you a way to estimate whether or not he's at serious risk or poisoning.....
Toxic Dose: Approx. 1 ounce of chocolate per 1 (one) pound of body weight
1 oz is approximately one square of chocolate, and that will help you if he's eaten a chocolate bar.
if your dog weighs 10 lbs or under and has eaten 10 oz of milk chocolate he is in serious danger.
But, if he weighs 120 lbs and has eaten 10 oz then he will probably get sick, but a healthy dog isn't likely to be in serious danger.
Toxic Dose: Approx. 1 ounce of chocolate per 5 pounds of body weight
So if your dog ate chocolate of this type, it takes less of it to cause serious problems.
If you take the same 10 lb dog from the previous point, he would only need to eat 2 oz of semi-sweet chocolate to be in danger of poisoning (as opposed to the 10 oz of milk chocolate).
Toxic Dose: Approx. 1 ounce of chocolate per 10 pounds of body weight
This is the most dangerous type and it's twice as dangerous for him if that chocolate was the dark or baking variety, rather than semi-sweet. Ten times as dangerous as eating milk chocolate!
Your 10lb dog will have ingested a toxic level of Theobromine from only 1 oz. of dark/baking chocolate!
If he weighs 50lbs and he's eaten 5 oz's he's in the same situation.
For a more accurate calculation of how much theobromine and caffeine was in the amount of chocolate your dog ate, check out this very useful 'Dog Chocolate Toxicity Meter'.
It uses your dog's weight plus type and amount of chocolate he ate to estimate how dangerous it is, and what symptoms you might see.
BUT, again, if there's any element of guesswork in your calculations, don't take any chances. Get vet help right away.
If you know your dog ate chocolate, depending on what type he ingested and how much he weighs, symptoms of a toxic level of Theobromine could include:
Whether or not you feel the symptoms your dog is experiencing are serious, it's vital to get veterinary help IMMEDIATELY if your dog ate chocolate - no matter how much, or what type.
Only a qualified vet can decide whether or not any treatment is needed and time is of the essence! The sooner your dog gets help the better his chances of making a full recovery.
Generally if there is any doubt about whether he's eaten enough to be dangerous, a vet will induce vomiting as quickly as possible to prevent any more Theobromine being absorbed into your pet's bloodstream.
If your own veterinary clinic/office is closed, take your dog to a 24 hour emergency pet hospital, this is not a 'wait and see' situation.
Although there may be a charge (around $65 at time of publication), I'd imagine your dog's life is worth much more than that to you, so if you need to - call them!