The phrase "to raise a litter" means to take care of and nurture a group of young animals, usually referring to newborn puppies or kittens. Full definition
While spending several hundred dollars to spay or neuter a pet may seem expensive, it is much less expensive than the cost of raising a litter of puppies or kittens. (ark-valley.org)
The bitch, at this age, is far from ready for raising a litter, but she is able to have it. (breedingbusiness.com)
For socialization purposes, it is always best to find a breeder who has raised a litter in the house. (thehappypuppysite.com)