There aren’t many facts available for this case. I hope he gets the stiffest penalty allowed. There is no reason to be cruel to any animal, and we all know that studies show the humans will be the next target.
Many times frustration over your own pet or a neighbors can lead to cruelty either intentional or reactive. There is help available check out www.dogpsychologyhelp.com or www.gooddogcentralcom if you or someone you know is frustrated with a dog.