Mac likes to compete in dog shows. He has an inflated sense of his own importance. Mac dislikes some of the things Cleo, Clifford, and T-Bone like, for example, nose the can, he thinks it is too noisy. He would do anything for a tummy-yummy, which is a type of dog treat in the series.
In the episode "Promises, Promises", when Mac was mad with Jetta for not keeping her promise to take Emily Elizabeth to the coral cave, Jetta tries to make Mac feel better with a tummy-yummy. Mac comes to get the tummy-yummy and smiles. When Mac gets the tummy-yummy, he goes back to being mad. In the episode, "King Mac", he is blamed by Jetta for making a big mess that T-Bone actually made... Also in the episode "Teacher's Pet ", Mac wouldn't do any of the tricks his teacher at dog school told him to do unless he got a tummy-yummy for it. At the end of the episode, his teacher even gave him a "tricks for treats" award.