Dogs - Medium-Sized Breeds
Border Collie
Border Collies are a breed of herding dogs developed in Scotland which were intended for herding sheep and other animals. They are extremely energetic and athletic and are often considered to be one of the most intelligent breeds of dog. In general they are medium-sized with double coats that can be many different colors, although black and white is the most common. They are seasonal shedders that require plenty of grooming. Males are usually between 19 and 22 inches and females are between 18 to 21 inches. They are very energetic so they need an active family that has plenty of time for their dog.
https://www.akc.org/breeds/border_collie/
Collie
Collies are graceful and fast. They are known for their beautiful coats that can be one of the four accepted colors. Although their coat is long and thick, they are very clean so you will only have to brush it about once a week. They used to be employed as herding dogs for cows and sheep. They are naturally responsive to humans and are very loyal. Male collies can stand 22 to 26 inches and the female collie averages 20 to 24 inches. The males are usually in the weight range 55 to 75 pounds and the females are usually 45-65 pounds. They have become a beloved family dog that requires daily walks, but is also content to just veg out.
https://www.akc.org/breeds/collie/
American Bull Terrier
American Bull Terriers are playful and friendly despite their appearance. They can be all white or multicolored. They are 21 to 22 inches tall and weigh between 50 and 70 pounds. They have a stocky muscular build but are very gentle. They are a very loyal breed and become very attached to their owners so they should not be left alone for very long.
https://www.akc.org/breeds/bull_terrier/
English Cocker Spaniel
The English Cocker Spaniel is a breed of gun dog. This breed has descended from the original spaniels of Spain. It is very active and happy-go-lucky. Their coat is curly and can be a solid color or particolored with various markings. They can be black, brown, reddish and golden, white and golden colored. There has been a link found between coloring and temperament of the dog that could be related to the color pigment melanin. Males are usually 16 to 17 inches and females are 15 to 16 inches. Males typically weigh 28 to 34 pounds and females weigh 26 to 32 pounds. They are a good, medium-sized family pet that is easily trained. Cocker Spaniels do not like to be alone and are very affectionate to their owners.
https://www.akc.org/breeds/english_cocker_spaniel/
Boxer
The Boxer was developed in Germany and is a medium-sized, short-haired dog. A Boxer’s coat is smooth, white, or brindled and may or may not have markings. They have an under-bite and very strong jaws for prey. Adult males are typically 23 to 25 inches and females are 21.5 to 23.5 inches. Boxers are very playful and contrary to popular believe they tend to be very good with children. They are also very strong and active, and require a considerable amount of exercise per day to prevent destructive behaviors caused by boredom like chewing. Boxers are not aggressive by nature and are generally quite patient. They are a very popular family and guard dog.
https://www.akc.org/breeds/boxer/