A sugar treat once in a while is ok for a horse. Too much of a good thing however will not be healthy for him but it would take a lot of sugar to rot his teeth. Instead of sugar cubes or other snacks with a high sugar content give your horse cut-up apples or Pears. Horses are big carrot eaters too. The rule of thumb is "if it's not good for you it probably will not be good for him either".
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yes
Yes.
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True
True
yes on howrse yes
It sure can! The horse will get cavities in its teeth if you feed it too many sugary treats.
Yes,their teeth are made of enamel just like ours,which makes them prone to cavities too.
If you feed a horse alot of sugary treats, yes. One or two is OK once in a while though.
Yes, too many sugary treats can and will give your horse cavities.