Hello, my name is***** and I have over 20 years of experience as a veterinarian. I can understand that you would be concerned about Hailee's strange episode Saturday night, being unable to normally bear weight on her left front leg.
Was she able to place the leg normally, it just wouldn't bear weight and the leg collapsed or was she carrying the leg?
What was she doing before this began? Sleeping or awake?
If you pinched her toes could she feel it?
Possible reasons for what you were seeing include a temporary loss of nerve function due to nerve compression. If she was sleeping on a hard surface or in a strange position before this began pressure on one or more of the peripheral nerves that control the leg/paw may have been compressed. There are a couple nerves that are relatively superficial, especially the radial nerve that sits on the outside of the elbow, that may have been affected. This is similar to what happens to us when we get that "pins and needles" sensation in our leg or foot and cannot walk properly.
Another possibility is a condition called FCE, fibrocatilagenous emboli, where a chunk of cartilage breaks off and lodges in the blood vessels that supply the spinal nerve roots. It is very painful initially as blood supply to tissue is blocked off. The pain only lasts a short time, less than a few hours to a day, but the weakness from the nerve damage it causes it can last for a few hours to weeks, or in rare cases is permanent. It really depends upon how severely the blood supply is compromised.
Less likely are spinal cord neurologic problems, such as an intervertebral disc(s) (cushions between the bony vertebrae) that are out of place or spinal arthritis putting pressure on the spinal cord or even a mass in or around the spinal cord. None of these should improve so quickly without any therapy or significant time for the inflammation to resolve.
While I too would be concerned since she seems normal now it seems reasonable to take a watch and see approach and make sure her beds are very well padded.
Please let me know if you have any further questions.