Quite a Handful
Being a vet who comes across fluff balls like this must be difficult not to appreciate your daily work. Though they would be lovely, he most surely had hands full trying to hold them all at once. Fortunately for him, his pockets proved to be a substitute for a cat-holder. On that day with so many kittens to care for, the clinic was most likely a little disorganised, but ultimately it's well worth it.
The likelihood is that these vibrant creatures are all brothers and sisters as the same cat litter can include several hair textures and colours.