McGee Equine Clinic frequently examines horses and other large animals for a variety of skin conditions: from patchy to scabby and everything between. If indicated we can perform diagnostic testing such as skin scrapes, cytology, biopsy, and bacterial or fungal cultures. We can treat your horse with either medical or surgical management depending on the situation. We see a variety of skin conditions; some common skin conditions that we manage include (but are not limited to):
Breaks in the skin lead to bacterial and/or fungal infections causing scaly patches, hair loss, and inflammation on the legs called scratches (aka grease heel or mud fever). Causes include contact allergies and irritants, infestation with Chorioptes mites (leg mange), and malformations with the lymphatic vessels, etc. Secondary infections are often worsened by exposure to moisture in mud or pastures. Draft breeds and other horses with feathered legs might be most susceptible.
Rain rot is skin disease caused by the opportunistic bacterium which thrives in moist conditions. Rain rot is usually evident over the horse’s neck, back, and croup, but can also spread to the legs. The skin crusts and raised tufts of serum-matted hair, called paintbrush lesions, form. The tufts usually shed, leaving hairless patches. Rain rot is contagious.
Ringworm is caused by a highly contagious fungal infection, not a worm, and is named for the shape of the skin lesions, which take on a ring-like appearance. Each ringworm forms a circle with a raised edge that encircles a hairless and often scabby patch.
Warts are caused by the equine papilloma virus and are often associated with young horses. The lesions usually form on the muzzle and lips; warts are contagious and spread via direct contact with horses suﬀering active breakouts.
Tiny insects, such as mosquitoes, ants, and a variety of flies, can cause big skin problems for your horse. Insect hypersensitivity is an allergic reaction, usually to a biting insect’s saliva, and is one of the most common equine dermatological issues. Bites can result in welts and bumps at the site of penetration, but can also lead to an outbreak of hives.
Sweet itch, aka Queensland itch or summer eczema, is a reaction to salivary antigens from the bites of Culicoides gnats (also called no-see-’ems). Small, itchy papules form on the skin. The horse’s mane and tail head are especially susceptible, and hair loss is often caused by rubbing the aﬀected sites is common. Scabbing and ulceration can result from this self-mutilation.
Ticks and lice and mange mites are common external parasites in large animals. Tick bites may lead to large swollen hypersensitivity reactions, that can be so severe they can resemble masses (“pseudo-lymphoma”). Lice, either biting lice or sucking lice, can cause itchiness or blood loss. Various types of mange mites can occur in diﬀerent large animals, and can result in itching, scaling, and bald patches.
A sarcoid is a nonmalignant but locally aggressive tumor most often seen on the head, belly, groin, and legs. The appearance can be quite variable, from flat and wart-lie to resembling proud flesh. Bovine papilloma virus (BPV) is probably a causative factor in sarcoids, and a 2010 study of 222 horses at the University Equine Clinic of Bern identified a possible genetic basis for sarcoid development in horses as well. Sarcoid treatment varies greatly, based on the size, location, and type of sarcoid, and every situation is slightly diﬀerent.
Approximately 80% of gray horses will develop melanomas by the time they’re 15 years old. These skin growths are tumors usually located near the anus, vulva, sheath, penis, ears, salivary glands, and underside of the tail. There are various treatments for melanomas including medications, vaccinations, surgery, and chemotherapy.
Hives are round, raised wheals over the body that cause the hair to stand up. They can range from the size of a nickel to several inches in diameter and can cover part or most of the body. A breakout of hives is usually related to air-borne allergens (e.g., tree, bush, weed, or grass pollen; mold; dust; etc.); ingested allergens (e.g., feed ingredients); or contact allergens. A breakout usually isn’t painful but might itch.
Various conditions occur on the sole of the foot in large animals. Common findings include thrush, canker, white line disease, abscesses, and foot rot.