You would agree with me that a cat needs its legs for mobility?
If a cat severly damages its knee when it jumps or moves around the Vet might say he will operate on the cat to fix the problem. (Well he really would not because the cat is a high risk for surgery). The LoopHole parents can expect to pay anything from US$1500 to US$3000 & higher to help heal the cat. About half a semester tution costs.
Read below about the very serious problems  Obesity in Cats ... and What to do About an Overweight Cat | petMD
__________________ REAP WHAT YOU SOW. LIFE IS SO NOT FAIR. | 
