If you cross a beagle and a Chihuahua, you'll end up with mixed breed puppies whose size and appearance run the gamut between the two pure breeds. It's likely you'll end up with a dog larger than the Chi and smaller than a beagle -- but you could end up with a dog the size of either parent. This canine combination is sometimes referred to as the "Cheagle."
Size and Appearance
The American Kennel Club beagle breed standard doesn't allow dogs over 15 inches tall, while the AKC Chihuahua standard doesn't allow dogs to exceed 6 pounds when full grown -- so the Cheagle ends up between these two weight extremes. Combining the two breeds means a dog might mature at about 12 pounds, perhaps standing 12 inches tall. The Cheagle could have the floppy ears of the beagle parent, or the stand-up ears of the Chi. Beagles are short-haired, tri-colored hounds, while Chis can be short- or- long-haired and any color or combination of colors. That means a Cheagle's coloring is hard to predict, as is coat length if the Chi side includes long hair.
The beagle and the Chihuahua sport distinctly different temperaments. While a beagle makes a good family pet, the Chi is usually a one-person canine. There's really no telling what sort of temperament a Cheagle might possess. Even if he favors the beagle side of the family physically, he could have the Chi's more high-strung temperament. He could also look like the Chi but boast the typical happy-go-lucky beagle spirit.