I am raising this topic to determine how widespread this condition is and how to treat it and avoid it. Not to be confused by the symptoms of leg mites, stomping, scabs and itchiness confined to legs. On our farm since we started keeping and breeding Suffolk horses in 1994 we have had 2 cases of what I would diagnose as "Sweet Itch". Both were mares, both had itchy raised bumps over most of their bodies. They would rub themselves raw at times. Usually went away in the winter. Could indicate that it is related to biting insects? These horses could still be worked in harness without much problem. Is this problem a genetic thing? The 2 cases we had were more than 20 years apart and not related.
We also had some allergy symptoms [skin irritation, respiratory problems, swelling in the legs, lethargy, depression, anorexia and colic both minor and severe resulting in the death of the individual] related to black walnut consumption, leaves, bark and pollen. Getting rid of most black walnut trees has almost eliminated this problem.
Are you having problems with "Sweet Itch"?

Ken Laing, Orchard Hill Farm, St.Thomas, Ontario, Canada

We have had a mare with "sweet itch". It does seem to start with an over reaction to bug bites, which become raised and don't go away then the biten area attracts more bites and cattle face flies collect there and the bite becomes a blistered like sore and the itching starts seriously. It seems the condition spreads from the bite spots to face and lower legs and continues throughout the season regardless of topical treatments with every substance we could find. Keeping the mare inside during the day and only allowed to graze at nights helps, but doesn't stop the condition. We've treated this with a homemade mixture of bacon grease and sulphur powder bought as a fungicide for garden use, stirred together when warmed in a double pan of hot water and mixture in separate pot. In winter, after fly season and long winter coat the condition goes away. It has been on the collar bed shoulder of this horse making her unworkable with a typical collar. I have also heard that it only occurs on lighter colored horses. I have heard that this condition is genetically transmitted to offspring but haven't observed that in the offspring of this horse. I also have heard that the same horses that have this condition also produce or carry the gene for crypt orchid (one testicle descended) male offspring. This "sweet itch" is a condition that occurs in the U.K. I have no direct references to the "heard" portion of this response, maybe someone can do some further research on it. This condition could be well explored through genetics and DNA information. Thanks for bringing this issue up Ken Laing.

Jennifer Diment ~ Maybe I’ll start an open conversation here if you don’t mind Jason Rutledge. As not all are on the ASHA page

Sweet itch is an allergy to biting insects such as midges gnats and black biting flies ect. Sadly it is an inherited gene however not always passed on Depending on circumstances it can either be a minor inconvenience or a major issue depending on how bad the area you are in is for such insects. I bred Abbe Marshall-Wyer filly who was out of a mare who shows little to no signs of the condition and by stallion who had no past history of it. Personally ordinarily the condition would not put me off having and horse with sweet itch however living in west wales (uk) we are fly and midge country as we are warm and wet year round, so for the welfare of the horse I would not keep a horse in this area. Hence why I sold folly to the amzing abbe and Paul.
The condition can be controlled with the correct management, topical lotions, bathing, rugs and veterinary injections however must be take seriously as untreated it can be severely disfiguring if not life threatening if infection sets in.

I personally would not breed a known horse with it unless it was horse for yourself. And definitely not keep a stallion entire with such condition.

Please note a horse could have the condition and not show any sign of until the correct conditions or levels of antigen are met to the horse in question. It is a an understudied area but progress has been made with a vaccine (in the uk) being trialed. Submitted from Suffolk Punch Draft Horse Facebook page post by Jennifer Diment, American Suffolk descendent owner in the U.K. by Jason Rutledge

Seeing if you get this by e-mail that I posted here. July 25, 2019 at 8:25 pm my time

Yes, I recurved this message