Jack is a mix between a Jack Russell and a Boston Terrier. He is black with white spots. (like the Boston) now 3 years old, very smart awesome family pet and very loving and obedient. When it's playtime, jack loves to fetch, swim and do tricks. Recently, Jacks hair around his eyes and behind his ears has thinned and also starting in front of his ears. Is this hair thinning a common issue with the breed?