RandomWiktor
Rabid Betta Activist

I would be concerned about such a degree of bruising in an outdoor cat simply because of the various and severe causes it could have. Traumatic injury is the most likely, but remember that many poisons cause hemmoraging, and some communicable feline diseases also may cause bruising or hemmorage. Is the cat vaccinated, and do you know of any neighbors who put poison out for rats and other vermin? If the cat is unvaccinated, or if you are aware of poison being used nearby, please urge your mother to take the cat to the vet promptly as the brusing could have a more serious cause than a HBC or attack from another animal. Either way, however, he should be seen by a vet, as such a noticable degree of brusing could be the tip of the iceburg; muscle, bone, and vessel could have also been damaged in the process.
Good luck convincing your mother.
