Ill Horse

Question
My horse is 22 years old, has always had a very good appetite.  4 weeks ago i found him with photosensitivity and took him in to a dark stable for 2 weeks, the vet says his temp, heart rate, liver and kidney's are fine but can't understand how he is loosing proteins.  His dung is very slack and has lost alot of weigh and now has a very poor appetite and likes to lie down alot.  In the 22 years I have had him I rarely see him lying down, he has had photosensitivity every year for the last 3 years!  he is in fields he has been reared in his whole life so I can't understand the change! prior to this he has only had it once.  He does not have worms.  As for his appetite his only interest is in Lamb mix! why I don't know - we are currently asking the vet if this is ok as he won't eat anything else, when in the past he would eat his own and every one elses - (he has never been an obese horse but has come out of the winter a bit overweight but not this year).  Is breeding is Anglo Arab.  His mother died 2 years ago she was nearly 40.  He has always had very good health and I'm worries sick, please advise.  Thank you"


Answer
There are a few reasons horses develop photosensitivity.  The most common one is the ingesting of toxins.  These toxins are typically found in the field the horse grazes in.  Keep an eye on his blood panel.  It is good that he's currently testing well with his liver.  I would suggest grabbing some friends to help, and walk the field to remove any toxic plants that may be lurking.

What concerns me is that he is eating a lamb feed.  I am not entirely sure on the specific nutritional differences from lamb to horse feed.  Although I do know that they are different animals with different sizes, and thus different have demands from the body.  While they are both ruminants, they may be as different as say a cat's verses a dog's nutritional needs.  Definitely discuss this with your vet, as he would know far more on the topic than I.  

As a last thought, you may want to have his teeth checked.  When the teeth are causing pain or unable to function correctly, the horse is unable to properly chew his food.  This seemingly simple action, actually plays a big role in the digestion process.  If the food is not properly chewed before entering the stomach, then it cannot sufficiently break down for the body to extract the necessary nutrients.