The last year in California has been an excellent year for rainfall. For most of the state, the drought has been declared over. With the extra moisture, plants thrived and grew, but so did the bugs. Flies are buzzing us — and our horses. With them comes a nasty skin condition known as cutaneous habronemiasis, more commonly called “summer sores”.

Habronema and Draschia are the names of the nasty little parasites that causes this sometimes-challenging-to-deal-with disease. They are two of the stomach worms of horses, and in their normal life cycle, do not seem to cause much harm. When the parasite get deposited in an area of the skin or other external area, they can wreak havoc. They cause a non-healing wound that oftentimes increases in size.

The most common places I see them are:
1) The eyes
2) On the sides of the face, often times following the path of the tear ducts down to the nostrils
3) On the lips
4) On sheaths and tips of the penis
5) On the legs, after there was an initial wound

So, how do we treat them? Often times, the animal needs to be dewormed. Ivermectin products work well. Your veterinarian will have to assess the best course of action, based on location. Ones in the area of the eye often will require manual removal. Ones that are on the skin oftentimes need to be debrided to remove the majority of the lesion.
While treatment will most likely require assistance from your veterinarian, prevention is always something the owner can participate in. Ways you can prevent this nasty infection are:
1) Fly control is a must. The parasite infests flies and is transmitted to these areas most often by them. There are many fly control strategies that can be employed, but cleaning up manure as frequently as possible is an excellent start. Some people will use fly sprays and fly control systems and fly traps. Others prefer more natural strategies such as fly predators and citronella. Whichever your choice, keep the flies under control.
2)Get wounds covered as soon as possible. The physical barrier of the bandage will keep the wound from coming into contact with the parasite.
3)Consider your parasite control program and discuss with your veterinarian what can help you best to prevent this disease.

Hopefully, you never have to deal with one of these. But if you do, do not wait. They can grow very rapidly in just a few days. Many times, I get clients say they were treating this, and just a few days previously, it was a small, little insignificant wound that had blown up overnight. If you are not sure, get your veterinarian out to help you decide if you have a “summer sore.”

~Dan