26/09/2026
PURPURA HEMORRHAGICA
Brian S. Burks, DVM
Diplomate of the American Board of Veterinary Practitioners®
394 Fox Road
Apollo, PA 15613
(724) 727-3481
www.foxrunequine.com
Purpura Hemorrhagica is an acute disease in horses characterized by extensive edema that is most common in the head and distal extremities but may also occur on the abdomen. This disease may also affect internal organs. It is most common following exposure to Streptococcus equi but can occur following infection or exposure to a variety of bacteria and viruses, including influenza, arteritis virus, and equine herpes virus.
Purpura, in Latin, means purple. Purpura hemorrhagica is noted by red or purple blotches in the skin or mucous membranes. As you can imagine, this can be difficult to identify in the skin of a horse, so we rely on observation of the gums, and, in mares, the v***a, as well as other signs. These small, red/purple areas represent hemorrhage under and within the skin, and can occur anywhere internally or externally, meaning that in addition to the skin, the intestinal tract, lung, brain, etc. may be affected.
Purpura occurs due to large immune complexes that form in the vascular system. Immune complexes occur with any disease, but when they become large, deposition into the blood vessel wall occurs, and, using various enzymes, damages the vessel, causing leakage. This is called a Type III Hypersensitivity reaction. The end result is edema (tissue swelling), hemorrhage, thrombosis, and ischemic (lack of blood flow) tissue.
Clinical signs of PH are varied. Frequently, elevated heart and respiratory rates are noted, along with fever, depression, and anorexia. The skin swells, often beginning around the nostrils, but can occur anywhere. This swelling is warm and painful to touch, resulting in some fast-moving limbs or a tail! The edema can progress to skin necrosis (death) and loss of fluids through the skin, and eventually the skin may slough, leaving granulating wounds.
This tissue swelling can occur in other systems as well, causing lameness, colic, difficulty breathing, and neurologic symptoms. Sometimes, a more severe form of PH occurs with multiple infarctions in the GIT, heart, and muscle. Secondary complications of PH include laminitis (founder), blood clots, and local infections. Less commonly, cardiac arrhythmias and renal disease may be secondary to PH.
Diagnosis is based largely on clinical signs. Routine blood work may show elevated white cell counts and low red blood cells counts. Hyperfibrinogenemia is also common. Fibrinogen is an acute phase protein produced in response to inflammation and infection. Muscle enzymes and renal values may also be elevated. Occasionally, there may be low platelet counts due to using them faster than they can be produced, or because they are targeted directly by the immune system.
Imaging of the respiratory tract via endoscopy and radiography (x-rays) is also important to look for discharge or enlarged lymph nodes, or infected lung. More specifically, the skin may be biopsied to look for signs of vasculitis.
Treatment goals are to remove the inciting cause, reduction of inflammation, reduction of the immune response, and general supportive care. Identification of the cause allows appropriate methods of removal, i.e., antibiotics for bacteria. The use of steroids reduces inflammation and the immune response. Some affected horses will require aggressive nursing care including wound care, hydrotherapy, bandaging, and fluid therapy. Hand-walking may help reduce edema of the limbs. Occasionally, abscesses may need to be drained or an emergency tracheotomy may need to be performed to allow for an open airway.
It is also important to monitor and treat for complications, including laminitis, cellulitis, pneumonia, colitis, and thrombophlebitis (clotted and infected blood vessels).
Fortunately, most horses do recover with aggressive therapy. Treatment may be from 2-4 weeks, or longer with complications. Extensive damage to internal organs or skin sloughing indicates a more guarded prognosis.
Dr. Brian Burks, Dipl. ABVP is the owner/veterinarian at Fox Run Equine Center, a 24-hour medical-surgical center near Pittsburgh, Pennsylvania. He is board certified by the American Board of Veterinary Practitioners (Equine Practice). This certifies him as an expert in all categories of equine practice. He enjoys the diagnostic and treatment challenges of internal medicine. www.foxrunrequine.com
Fox Run Equine Center
(724) 727-3481
