* The individual dog's genetics: Some dogs are genetically predisposed to having larger litters than others.
* The age of the mother dog: Older dogs tend to have smaller litters.
* The health of the mother dog: A healthy mother dog is more likely to have a larger litter.
* The size of the father dog: Larger dogs generally have larger litters.
On average, Irish Setters have litters of 6-8 puppies. However, it's not uncommon to see litters with fewer or more puppies.