Is it true that lifting a cat up by their armpits and letting their feet hang causes them breathing difficulties?

Absolutely not. Cats are capable of holding their breath for short periods and can go much longer in certain situations if needed. In fact, cats will sometimes choose to hang from trees, limbs, or even your arms by the armpits in a behavior known as "brachiation". During brachiation, cats hold the weight of their bodies with their forelimbs but don't show any signs of breathing difficulty or distress.

That said, it's important to note that picking up cats by the scruff isn't recommended unless absolutely necessary — like when you need to move them away from danger. That is because holding a cat by its scruff can cause discomfort or pain due to an increase in pressure on the sensitive nerves located there. So while lifting your cat up by its armpits may be OK occasionally, try not lifting them too often as it's best for both pet and parent!