Veterinarian/ homeopathic Doctors/p help us?

My English is not good.Last year I found a seriously ill homeless puppy.I was crying about saving a puppy.The animal organization was just saying Let him die - throw him away.Rescue veterinarian did not pay any attention to his suffering.Now A street dog and cat are giving birth soon.For his there birth control.How do one trust on animal center?homeopathic Doctors p suggest a pills for this animals birth control.At which month it is safe to give them medicine?How to understand how many month is cat Pregnancy ?And which month is safe for cat for birth control?Birth control of of cat stop bith of kittens.Does it sin?