For horse owners, dealing with summer sores on a yearly basis can be frustrating and disheartening. Knowing what causes these nasty, itchy lesions, and how to prevent and treat them, can help you enjoy spending time on horseback this spring and summer, instead of waiting vainly for your horse to heal.

Causes of Summer Sores

Habronemiasis, commonly referred to as equine “summer sores,” is a parasite-caused skin condition that usually affects horses during the spring and summer months when fly activity is at its highest peak.

These infestations occur in cyclical fashion when the common house or horsefly ingests the larvae of an equine intestinal parasite called a nematode. Typically, the larvae are deposited in the pasture or stable area in feces from horses infected with this particular worm and then ingested by the fly. The fly then leaves the larvae on wounds, abrasions, or moist areas of the horse’s body, such as the eyes, the corners of the mouth, ears, or genitals when it bites your horse. Subsequently, if the larvae are left on the skin of the muzzle, they get ingested by the horse, grow to the adult worm stage in the animal’s stomach, and then produce larvae that are, in turn, passed out in feces and ingested by other flies.

These larval infestations on the horse’s skin can cause inflammation and intense itching, resulting in the animal biting, scratching, or chewing at the infected area to help alleviate the pain. This often leads to secondary bacterial infections that delay the healing process.


Summer sores appear as ulcerations on the horse’s skin, and because of the scratching, are often open and bloody. You will typically see them in warm weather months, and they seem to regress in the fall and winter. Summer sores can affect all horses, mules, and donkeys. There is no breed or sex predilection, although some animals seem more prone to the equine infection than others, developing the lesions year after year.

The rapidly-growing skin lesions resemble moist, pink granulation tissue with an irregular shape. Inside the sore, you might see small, hard, yellow grains that are a tissue reaction to the inflammation. Horses whose eyes are affected often show excessive tearing and squinting. Stallions and geldings that have an infestation of the penis or sheath may have difficulty urinating.


The best prevention of summer sores begins with fly control, using a combination of fly sprays, masks, and sheets to keep your horse from being bitten. The use of fly strips and fans on stall doors helps to decrease the number of flies in your animal’s environment, as does a barn or stable spray. You should also dispose of any soiled shavings or bedding that could attract insects.


Treating summer sores is two-fold. You must first get rid of the intestinal parasites causing the sores by beginning a strict deworming program. Any equine veterinarian or equine supplies store can provide you with an anthelmintic (deworming medication) containing Ivermectin that will kill the adult worms in your horse’s intestines. To be totally effective, you will need to treat your animal at least twice a year, in the spring and in the fall.

To heal the summer sore lesions, modern veterinary therapy has always included using an antibiotic topical ointment infused with steroids to decrease the itching and inflammation. Because multiple bacteria have become resistant to antibiotics over the past 25 years, this system is no longer working as well as it once did. Expensive and prolonged courses of antibiotics have gotten either minimal responses with possible side effects, or have been shown to be totally ineffective in treating the disease.

Silverquine® is a new water-based topical gel that has been clinically proven to work on equine skin problems, including rain rot, thrush and hoof thrush, ringworm, summer sores, and equine wound care.

Based on traditional veterinary medicine that used silver to help treat wounds and other infections in animals prior to the invention of modern-day antibiotics, Silverquine® is an ALL NATURAL product that contains no alcohol or synthetic chemicals to inhibit stem cell growth or epithelialization – the growth of granular tissue over open wounds.

In addition, our Silverquine® Technology consists of silver nano molecules (less than .015 micrometers in size) suspended within a water molecule. Our gel has been safety tested and proven more beneficial than silver sulfadiazine cream, a veterinary cream that contains 100 times the amount of silver found in Silverquine®. Silverquine® has even proven so non-toxic that it can be used to treat eye infections in horses without adverse effects.

Don’t wait until warm weather causes problems for your horse. Be prepared for any skin, eye, or hoof issues this summer, and keep a tube in your equine first aid kit.

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