My daughter has a teenage horse who used to jump a lot-- her legs have definitely been around the block a bit. She moves sound, but I've noticed that walking around under saddle, she stretches her head down to rub the inside of her right knee quite a lot -- probably 4-5 times in a 15 minute warm-up walk. She really rubs hard with the side of her muzzle!
It just got me wondering if this could be a sign of an issue within her joint . . . would you try anything like a little liniment or . . . ? Or is this normal??
Most likely, the horse is rubbing her face, not her knee. Horses get itchy around their lips and jaws from the bit and noseband; given the opportunity, many horses will rub their noses on their legs or people. Since parts of the bridle or bit can get caught (on boots, or people's clothing) it's usually a good idea to discourage the rubbing until the horse is untacked and the bridle is removed.
Some horses experience discomfort from traditional bridle fit. The Micklem bridle is designed around the horse's facial structure, and may alleviate the need to scratch.
If your horse was truly scratching its knee, it would use its teeth to "chew" at the itch. Rubbing the side of the face is very common behavior and typically doesn't mean anything is wrong.
“A clever person solves a problem. A wise person avoids it.”
? Albert Einstein
Most likely, the horse is rubbing her face, not her knee.
Yes, that sounds like face rubbing to me, too.
As AJ mentioned, it's probably nothing, but I'd still double check and make sure that the bit and bridle are clean and fit properly, and I'd also take a good look at the skin to check for grime build up or fungus. Really, it is pretty common, though most of my horses have been more interested in trying to rub when being cooled out when their faces are all sweaty.
"In order to really enjoy a dog, one doesn’t merely train him to be semi-human. The point of it is to open oneself to the possibility of becoming part dog."
Usually it just means an itchy/sweaty face and winter can make that worse with more dirt and sweat. Sometimes it can get to be an evasion, however. It's OK to let them scratch but not if they're being rude about it.