First up, and one that may not come as a surprise to most, is the pug. These wrinkly-faced little pups are known to have trouble breathing because of their flat faces.
They can be trained to swim, but this won't feel natural because of the unique conformation of their long bodies, barrel-shaped chests, and long legs, which don't get along very well with water.
When it comes to swimming, dachshunds face the same problems as corgis: long bodies and short legs.
That's not to say they can't swim, but they're more likely to have trouble breathing and keeping their head above water if they're in the water for too long.
Shih Tzus also have short muzzles and short legs, making it challenging to keep their heads above water.
These short-legged hounds were initially bred for hunting, but you should expect to avoid seeing your basset continue hunting that leads to any deep body of water.
They will naturally struggle to adapt when kept in cold water and will thank you for letting them play on land instead of water.
Bull Terriers are not natural born swimmers, their deep chests and short legs will make swimming more challenging.