| lumps on the horses’ skin or hair by running your hand over the horse’s coat. Later it can appear as large crust-like scabs, or small 1/4 inch matted tufts of hair. There are usually dozens of tiny scabs that have embedded hair and can be easily scraped off. Underneath the scabs, the skin is usually pink with puss when the scabs are first removed, then it becomes gray and dry as it heals. It is usually hard to differentiate rain rot from other similar skin conditions, so if you are unsure, call your veterinarian.
Rain rot can be found anywhere on the horse’s body, although the most common areas are on the back and rump, along with the back of the fetlock and front of the cannon bone. Other areas are around the eye and lip margins and at the tips of the ears - areas that are exposed to trauma. When rain rot appears on the lower limbs (behind the fetlock), it is most commonly referred to as “dew poisoning,” “greased heels” or “mud fever.” Again, it’s caused by the horse standing in water, or by excessive dew on the grass that keeps the feet wet. It’s almost always associated at the fetlock with white skin, not dark skin.
In order for a horse to get the disease, several conditions have to exist. You have to have an infected carrier animal, or a fomite such as a brush, blanket, or saddle that has the organism in the form of a spore that makes contact with the susceptible horse. There has to be some form of extreme moisture, like heavy rainfall. Horses that have heavy hair coats keep the moisture in contact with their skin, which helps the spores grow. And, the skin has to be damaged - from an insect bite, cut, or scrape. That lets the organism get down into the epidermis.
It is extremely difficult to prevent the spread of rain rot, since a horse can pass it to another horse by simply rubbing its skin on any object that the other horse may touch. The best way to prevent its spread is to use some form of disinfectant, wear gloves while working, and wash your hands thoroughly after working with an infected horse. It’s important to disinfect anything used on an infected horse before using it on another horse - halters, saddle pads, brushes, etc. Also, if the horse being treated is blanketed, make sure to wash the blanket to prevent re-infection. If the horse has a favorite place to rub, like a stall door or a fence, it can even become a source of the organism.
A good solution to use for disinfecting is 2 tablespoons of Chlorox to 1 gallon of water. Do not use this solution on your horse, only on the equipment!
The organism is considered an aerobe or a facultative
anaerob. That means it prefers carbon dioxide or a lack of oxygen to grow. So, you need to get rid of the heavy hair coat and the scab that’s holding the organism into the skin.
The best treatment is to wash the horse with soap (like an iodine soap) or antimicrobial and antibacterial shampoos and rinses. These medications help to kill the dermatophilus congolensis organism. If povidone-iodine (Betadine), Chlorhexadine, Phenol or Nolvasan is used, they should be applied once a day for one week.
The cleaning solution should be one that lathers well to work the crust off that’s created by serum oozing out through the skin. With gloves on, vigorously lather the horse well and try to break the scabs off, let sit for 10 minutes, then rinse. Getting all the scabs off and letting the air get to the ulcerated areas is the most important part, and it is the most difficult.
The scabs do not hurt the horse. Nor have they been associated with an “itchy” feeling. However, many horses will be resistant to the removal of the scabs since it can be painful, so be very gentle and take your time. A recommended way to remove these scabs is to temporarily moisten them (so they become soft and easy to remove) before lathering.
Since it’s painful, sometimes it takes a couple of days working a little at a time. Be sure to follow with a conditioner that works well and allow the horse to dry completely after scab removal. Continue this daily for 1 week.
It is not recommended to use ointment on any areas but the pasterns because it holds moisture into the skin (and moisture needs to be removed for the condition to cease). If you use an ointment on the pasterns, such as Desitin or an antifungal, remove the scab so the medication can get to the organism and hold the water away from the skin. |
