Senior dog breathing weird, help?

ok i have an older dog named brownie, hes a nine year old lab/pit-bull mutt mix, hes acting fine and eating well but his breathing sounds weird, kind of like hes taking little bitty breaths as he inhales and then exhaling really deeply, he's his usual active self and is eating well as i said so nothing is alarming me right now, i was just wondering why he's breathing like this and what i can maybe do about it or if its not a problem, any suggestions will be appreciated