Winter coat in the summer and summer coat in the winter

I have a 4 year old gelding and for the past 2 years I have noticed a BACKWARDS shedding pattern. For example, by the middle of June, he grew a thick winter coat. He began shedding this coat in October and now is completely slicked out. He is otherwise healthy and his coat is very shiny. He had a similar shedding pattern last year but I did not keep records of the exact dates.

I have done tons of internet research but I don't ever find anything about shedding patterns that are completely backwards. We have moved to several different barn since last year, but the shedding patterns were pretty consistent in the past few years.

Any ideas as to what would cause this type of shedding pattern?

Thank you for your help!

The only thing I can think is a change in the weather confusing him! My horse started to get hairy earlier on this year, then shed all that, now he's really hairy again

Most animals change their coats according to day light actually, so unless you have him intentionally under artificial lighting (assuming not) it could be a hormone (specifically thyroid or cortisol) imbalance. Call your vet and pick their brain- phone calls are free!

It could definitely be a hormone imbalance or he could be not getting enough protein in his diet, but you said his coat is shiny and nice, so probably not... you could try brushing him more in the spring to help him shed it out