Don’t share the ice cream cone, sandwich, or any other milk-based product with your dog period.
On a hot day, it may be tempting to share your ice cream cone with your dog. But if your dog could, it would thank you for not doing so. Milk and milk-based products can cause diarrhea and other digestive upset as well as set up food allergies (which often manifest as itchiness).
This article was taken from http://pets.webmd.com/dogs/ss/slideshow-foods-your-dog-should-never-eat and reposted by New York Dog Nanny.