The RSPCA in the West Midlands is caring for 22 animals with pet food and pet meds after they were dumped in the area in five days.
A further two animals were found dead and three had to be put to sleep. The charity says it is "appalled" by the number of pets abandoned.
RSPCA inspector Scott Vanes said: "This is despicable behaviour and we must make it clear to anyone thinking of dumping a pet that it is a criminal offence to abandon any animal in a manner likely to cause suffering."
He added that there is no excuse for this sort of conduct and said this "cold, calculated and callous behaviour must stop".
In one case, six young cats were found on a blanket on a layby in Birmingham. One of the animals escaped and three were so ill that they were put down to end their suffering.
The last two are now receiving treatment from vets at the Birmingham Animal Hospital.