Allergic skin diseases in the horse.

The research article is about understanding the different types of allergic skin diseases in horses, which mechanisms trigger these conditions, and how they can manifest. The aim is to equip veterinarians with the knowledge required to correctly diagnose and treat these conditions in a regular equine practice.

Understanding Allergic Skin Conditions in Horses

• Allergic skin diseases in horses are the result of abnormal immune responses causing changes in various skin layers and occasionally in the subcutaneous tissue. These conditions are triggered by antigen-antibody reactions leading to different types of immune responses.
• The study identifies four types of immune responses in horses. Type I reactions are immediate and can cause peracute or acute hypersensitivities. Type II sensitivities involve circulating antibodies that do not cause skin diseases. Type III reactions precipitate into skin hypersensitivities. Type IV reactions are delayed and frequently result in skin lesions.
• These immune responses are elicited by antigens which can enter a horse’s body through inhalation, ingestion, surface contact or by parenteral administration which involves drugs or insect allergies. Type I reactions are usually associated with humoral serum antibodies, while delayed sensitivities occur over several hours to days due to a cellular response.

Identifying Allergic Skin Conditions in Horses

• The symptoms of skin allergies in horses and animals usually become noticeable when the acute symptoms like itching or edema formation become severe. Chronic conditions can present as persistent or recurrent itching, loss of hair or pigment, scrapes, thickened skin, or sometimes as a nodule or pustule.
• Some allergies may also manifest alongside other abnormalities in body systems such as the eyes, respiratory system, or the gastro-intestinal tract. The severity and frequency of these symptoms prompt attention from veterinarians for correct diagnosis and treatment.

Immune Pathology and Routine Equine Practice

• Although immune pathology is involved with most skin diseases, this article is focused on allergic skin conditions that are likely to be seen in common horse care practices. Parasite-induced allergic skin diseases such as cutaneous onchocerciasis and cutaneous hypersensitivity are discussed as an example.
• The study also regards related skin disorders like ventral midline dermatitis as parasitic diseases that may involve differential diagnoses for parasites such as Onchocerca, Habronema, or Lyperosia (horn flies). These findings are useful for professionals in equine veterinary practice for accurate identification, diagnosis, and consequent treatment of these conditions.