Is this considered neglect?

My son goes to his dad's for 11 hours every other Saturday and 4 hours every other Thursday. There have been 3 days in which my son's diaper has not been changed at all while he is with him. One of these days was a Thursday (4 hours is tolerable I guess) but the other 2 were on Saturdays. He went over 11 hours (since I changed him about 30 minutes before his dad picked him up) without a diaper change. He is 2 years and 4 months old. He only wet the diapers, no poop but still they were SOAKED. The reason I know they are the same diapers is because they NEVER go to Target or use their diapers and those are the ones I use. Is this considered neglect? Poor thing is sopping wet when he gets home!