Answer:
15 puppies
Step-by-step explanation:
First, let's define the term "Litter"
Litter is defined as multiple animals that are born at the same time from the same mother.
In Pongo and Perdita, they had a litter of 15 small puppies. The maid announced that only 14 survived, however, Roger was able to bring back the 15th puppy to life by performing cardiac message on it.
Later in the novel, these puppies are kidnapped and the journey of of Pongo and Perdita to save them begins.
Hope this helps :)