Symptoms and Treatment Methods of Sheep Photosensitization
Sheep photosensitization is a disease caused by photodynamic substances in the sheep's skin, which makes light-colored skin react too strongly to sunlight and results in skin damage.
Expert disease analysis.
(1) Causes: This disease can be divided into 2 types: primary photosensitization and secondary photosensitization:
Primary photosensitization: photoactive substances from plants such as hypericin, fagopyrin, and substances from plants of the Apiaceae and Rutaceae families can cause photosensitization in livestock and poultry. Clover, alfalfa, cow parsley and brassica are also related to photosensitization; certain coal tar derivatives such as phenothiazine, as well as sulfonamide drugs and tetracycline, can also induce photosensitization.
Secondary photosensitization: This is currently the most common type of photosensitization in sheep. It occurs because the secretory function of the liver and gallbladder is impaired, and the photosensitive substance phylloerythrin (a porphyrin) accumulates in the plasma, leading to the occurrence of this disease. Under normal conditions, phylloerythrin is absorbed into the bloodstream and effectively secreted by the liver into bile. Liver failure or bile duct damage caused by various reasons (dicrocoeliasis, various plant toxins that damage the liver, as well as phosphorus, carbon tetrachloride, etc.) can all lead to impaired liver secretion of phylloerythrin, increasing the phylloerythrin content in the bloodstream, thereby reaching the skin, absorbing and releasing light energy, and triggering phototoxic reactions.
(2) Symptoms: Sheep with photosensitization will show photophobia under sunlight, displaying restlessness and unease, rubbing and scratching exposed light-colored skin areas such as the face, ears, eyelids and muzzle, with rapid appearance of erythema and soon edema. If exposure to sunlight continues, marked plasma exudation can be seen, and the skin becomes crusted and necrotic; in sheep with hepatogenous photosensitization, jaundice may appear on the mucous membranes.
Expert treatment.
Prevention and treatment: For sheep whose photosensitization continues to progress, they should be kept in shaded areas and fed only at night. Early injection of adrenal cortical hormones or diphenhydramine (40 mg each time) is effective, and spraying the body surface with 1% potassium permanganate. To reduce exudation, 2-3% alum water can be used for cold compresses on the affected skin and 10% calcium gluconate can be injected intravenously. If the blisters have been infected by bacteria, potassium permanganate solution can be used to flush them, then zinc oxide ointment or anti-inflammatory ointment can be applied, along with intramuscular injection of penicillin and streptomycin. In addition, flies should be prevented from disturbing the animals.