Mane loosing hair

[Bellas Babies]

My horses manes seem to be getting thin and one even looks like she has a mohawk in a spot about a foot long??? What in the world could be causing this? What do I need to do - is there a deficiency??

 

[Wings]

Are they itching and rubbing on things? Could they be rubbing the mane out?

 

[Bellas Babies]

They have been rubbing alot lately...what do i need to dao about that- is there a reason for alot of rubbing??

 

[Wings]

Could be a skin irritation, could be lice. How does the skin look under the hair, is it raw or flakey? Are there any bites?