For puppies and kittens, size really does matter.
Shelters say smaller animals get adopted faster, and animal experts say the runt of a litter tends to be better protected by the mother. Pet owners-to-be tend to heap attention on them, since they're attracted to big heads on little bodies.
“Humans are drawn to animals or beings of any kind whose proportion of eyes to head is large,” said Dr. Julie Meadows, a faculty veterinarian at the William R. Pritchard Veterinary Medical Teaching Hospital at the University of California, Davis. “It's why we all coo when we look” at babies, whether they're human or animal.
For runts destined to become family pets, their size is their greatest risk before birth but also their greatest appeal after birth.
“It's the underdog, undercat thing,” said Gayle Guthrie, founder-director of Stray Love Foundation in Magnolia Springs, Ala.
At Stray Love, smaller rescue dogs are adopted five times faster than the larger ones. Meadows said that could be a result of the growing popularity of so-called pocket puppies — teacup dogs bred to be small and stay small.
“Pet owners are looking for that really cute runt equivalent, almost like we are selecting for runted creatures because we like those little things that can ride around in our purses and strollers and never weigh more than 5 pounds,” Meadows said.
A litter has only one true runt, but not every litter will have a runt. Litter-bearing mothers have Y-shaped uteruses. Those at the centre of the Y get the least amount of food and have the greatest chance of being runts, while those closest to the mother's blood supply get the most nourishment and have the highest birth weights, Meadows said.