I love dogs
That's awesome! The dog was actually the first species to be domesticated and has been selectively bred over millennia to do a bunch of different things!
I see. I have 5 different breeds of dogs
Breeds are completely controlled by humans! What breeds do you have?
pit bull. chihuahua, Rottweiler and so on 
Oh wow. Rottweilers are often put into dog fights, which are actually banned in the US (thank god!) 
I will never do that to my dog. My house is a heaven to them
Rottweiler
The Rottweiler (, ) is a breed of domestic dog, regarded as medium-to-large or large. The dogs were known in German as , meaning Rottweil butchers' dogs, because their main use was to herd livestock and pull carts laden with butchered meat to market. This continued until the mid-19th century when railways replaced droving. Although still used to herd stock in many parts of the world, Rottweilers are now also used as search and rescue dogs, as guard dogs, and as police dogs.
kidney lesions and increased cancer risk. This effect is also seen in different breeds of dogs, where smaller breeds of dogs typically live significantly longer compared to their larger counterparts. Selectively bred for their small size, smaller dog breeds like the Chihuahua (average lifespan of 15–20 years) have the B/B genotype for the IGF-1 haplotype, reducing the amount of IGF-1 produced. Conversely, large dogs like the Great Dane (average lifespan of 6–8 years) are homozygous for the IGF-1 I allele, which increases the amount of IGF-1