Coat went from shiny to dull?? Would rain do that?

We had a week of rain and during that time, my previously shed out boy, Citrus, either grew a coat or the rain dried his skin out.... or maybe the fly spray is dulling his coat....

His coat lacks luster. He has no other symptoms of illness and is up to date on vaccinations. What would cause his coat to go dull?

He is a full time pasture boy, with a couple of handfuls of grain when we put him away. He is only four with no previous history of disease.

I know I posted this picture in another thread. It is just the best one to see his non-shiny coat.

My mare did this fully shedded out last week then yesterday iit was like her winter coat was coming back in. Vet said it was due to the early and rapid coat shed this summer that there getting colder now. Usual years there shed would not be finished yet at all.

I don't think it's a health related issue, he looks like a very healthy horse. I bet it was the rain. Being a little bit colder probably caused him to puff his hair back up and if he was wet constantly, he is probably lacking some of the skin oils now that make the hair so shiny. I would just give him some time and if he isn't slick and shiny again in the next few weeks, then worry about a possible health issue.

Does he have access to free choice minerals? Not just a salt block either...but minerals? I know a lack in certain minerals can cause an improper shedding pattern and dull coat. In a dark colored horse a lack in copper can cause a copper colored mane and tail to come in, as well as a dull hair coat.

He does appear bright eyed though, and his coat doesn't appear 'dry, or brittle' by anymeans....maybe just spend some time really grooming on him, and that may bring out the sheen in his coat; he may just not be fully shed out yet either, as it is still early in the 'spring' yet. Two of my horses aren't even done shedding yet.

Does he have weird little scabby clumps of hair falling out on his back? If so, that's rainrot. Rainrot can definitely make the coat look like his....

My horse got a pretty wicked bout of rain rot, but you couldn't really tell just by looking at her. Here is a picture of her when her coat dulled out:



She doesn't look too bad in that pic, but compared to how she usually looks, it was alarming. Here she is normally:




I added a coat supplement and treated for rainrot. The second picture is just a couple of weeks later.