I dont know about horses, but for dogs it is deadly. There was a press story a few years back, a race horse was given a mars bar as a treat before a race and when it won, there was a hoo ha about it. The horse was elimiated from the race, I think it did Mars the world of good in publicity, but as for the health of the horse, it won!!
that's because chocolate contains theobromine - a substance prohibited under Jockey Club rules (The threshold level is 2 micrograms per mililitre in urine).
[qoute]Poisons
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Dangerous foods
Some foods commonly enjoyed by humans are dangerous to dogs:
Dogs love the flavor of chocolate, but chocolate in sufficient doses is lethally toxic to dogs (and horses and possibly cats). Chocolate contains theobromine, a chemical stimulant that, together with caffeine and theophylline, belongs to the group of methylxanthine alkaloids. Dogs are unable to metabolize theobromine effectively. If they eat chocolate, the theobromine can remain in their bloodstreams for up to 20 hours, and these animals may experience fast heart rate, hallucinations, severe diarrhea, epileptic seizures, heart attacks, internal bleeding, and eventually death. A chocolate bar can be sufficient to make a small dog extremely ill or even kill it. Approximately thirty grams of baking chocolate per kilogram (1/2 ounce per pound) of body weight is enough to be poisonous. In case of accidental intake of chocolate by especially a smaller dog, contact a veterinarian or animal poison control immediately; it is commonly recommended to induce vomiting within two hours of ingestion. Large breeds are less susceptible to chocolate poisoning, but still are far less tolerant of the substance than humans are.
Note:Carob treats are often available as dog treats; these are unrelated to chocolate and are safe.
It has recently been confirmed that grapes and raisins can cause acute renal failure in dogs. The exact mechanism is not known, nor any means to determine the susceptibility of an individual dog. However one vet [1] believes it may be an acute auto-immune response to plant-borne viruses [2] in the same manner as FIP in cats. While as little as one raisin can be fatal to a susceptible ten pound dog, many other dogs have eaten as much as a pound of grapes or raisins at a time without ill effects. The dog usually vomits a few hours after consumption and begins showing signs of renal failure three to five days later.
My horse is a bottomless pit so will have to try him with some
he already loves sour cream and chive pringles and those salty chip stick crisp thingys.
As for dogs and chocolat - yes it is deadly for them, but dark chocolate is the worst offender of the chemical. Milk and white chocolate have milk and other stuff in them which "waters it down" in effect. Hence they would have to eat a lot more of it for it to become deadly