Most people agree that a bouncing and blundering puppy is about as cute as animals gets - except for the smelly downside - number twos.
For their size, puppies burn an inordinate amount of energy - spending most of the day chewing anything with corners and barking at mirrors.
If a 20 stone builder were to behave in this way he would need something like 30 cooked breakfasts - impossible with a job to do, or without one money wise.
Therefore nano-technologists have developed a micro-nuclear reactor that can replace the mut's tiny stomach and provide unlimited energy for up to 20yrs - usually enough for 'a dogs life'. The animal can then be disposed of in the same way as high grade uranium. Due to the half life of Uranium, visits to the pet cemetary will not be possible for 15,000yrs.
Ironically, whilst the animals will no longer poo as such, farting will be highly radioactive rendering fond owners hairless or sterile although they will be able to x-ray themselves at the time.