Fluoroquinolones and photosensitivity in ducks

The photosensitivity of ducks refers to the disease of blisters or ulcers in the upper beak and web epithelium of ducks caused by ultraviolet radiation of sunlight after eating substances containing photosensitivity. The disease is characterized by deformation of upper beak and flippers of diseased ducks, exfoliation of keratinized layer and conjunctivitis of eyes.

1. Clinical symptoms and pathological changes of the disease

The disease can be seen in all breeds of ducks, the age of onset tends to be younger, and occurs evenly in all age groups after 10 to 20 days of age; the morbidity varies, the mortality rate is generally low (if there is secondary bacterial or virus infection can cause high mortality), the disability rate is high, the sales phase is not good. At the beginning of the disease, bloody spots or blisters appeared on the back surface and webbed back surface of the duck's upper beak, then gradually expanded, and finally collapsed to form a scab, which fell off about 10 days later, revealing pink or brownish-yellow ulcers. With the development of the disease, the upper beak begins to deform, shorten, or turn upward and outward, the tip of the tongue is exposed, affecting eating; tears in the eyes, inflammation of the conjunctiva, and severe adhesion. If there is no secondary infection, there are no other visual lesions except for the emptiness of the digestive tract.

Second, etiology

1. The feed composition contains seeds of some plants (such as large chondrograss seeds) and root blocks (such as root blocks of Ligusticum chuanxiong), which are rich in photosensitive substances or fluorescein. Ducks can cause the disease after eating feed containing these substances after continuous exposure to outdoor sunlight for a period of time.

two。 According to Guo Yupu, duck intake of excessive quinolones can also induce similar symptoms of the disease. In addition, it was found that ducks living in water sources seriously polluted by chemicals for a long time also developed similar symptoms of the disease (which may be related to corrosive chemicals).

Recently, the phenomenon of photoallergy in ducks has occurred frequently, which is characterized by the fact that most of the disease occurs in the treatment or rehabilitation period of other diseases, and has the experience of the use of fluoroquinolones. There is a causal relationship between the use of fluoroquinolones and photoallergy in ducks in some aspects, that is, what is the relationship between the use of fluoroquinolones and photosensitivity? For a long time, people have done a lot of in-depth research on this kind of drugs from various aspects. Fluoroquinolones play an important role in antibiotics and are widely used in clinic because of their strong and unique antibacterial activity. However, the adverse reactions of these drugs, such as photosensitivity, drug eruption, skin itching, burning sensation, affecting the metabolism and development of animal cartilage tissue (especially serious for young animals), are particularly emphasized in the pharmacology of these drugs. According to Xie Bin, animal experiments have found that fluoride can damage the cartilage of young animals. As we all know, an appropriate amount of fluorine is beneficial to animal bodies, while excessive fluorine is harmful to the growth and development of animal bodies. Fluoroquinolones contain one or more bound fluorine in their molecular structure, which may be an important factor causing cartilage metabolism, developmental disturbance and photoallergy in animals. On the other hand, there is cartilage tissue in the beak and flippers of the duck, and the younger the age is, the more abundant the cartilage tissue of the beak and web is (so is the bone tissue). Therefore, the cartilage tissue in these parts is also the most vulnerable to fluoride damage. At the same time, the damage of ultraviolet radiation to epidermis is definite. The young epidermis of the beak and flippers of the duck are exposed. The younger the age is, the more fragile these epidermis are and the most vulnerable to UV damage. For this reason, aggravation aggravates each other's damage to skin and cartilage tissue, resulting in the first damage to the duck's beak and web. Interestingly, the actual clinical practice also found that ducks with photosensitivity or similar symptoms were most common at the age of 10-30 days, and the younger the age was, the more serious the disease was; and most of these ducks had been treated with fluoroquinolones (such as serositis, colibacillosis, etc.) before the onset of the disease. In summer, the use of difloxacin hydrochloride, levofloxacin and lomefloxacin can easily lead to similar photoallergic symptoms in ducks. According to Guo Yuxi, ducks eating too much quinolones can also induce similar symptoms of the disease. It can be predicted that the side effect of fluoroquinolones on ducks (especially young ducks) is a double risk of ① photohypersensitivity, and ② affects the growth of ducks (mainly caused by metabolic and developmental disorders of duck cartilage). If the use of excessive fluorine in the feed of phosphorus and calcium sources may aggravate the side effects of fluoroquinolones on ducks, which should attract the attention of users (especially in the season of intense sunlight). From this point of view, in addition to ultraviolet light, there is a causal relationship between the use of fluoroquinolones and photoallergy in ducks, but whether it is related to the fluorine contained in the molecular structure of these drugs remains to be studied.

III. Diagnosis and prevention

According to the clinical characteristics, we can accurately judge the disease and avoid contact with various factors related to the disease (especially strong sunlight). Adequate vitamin A, D, E, C, nicotinic acid, increasing the level of amino acids in feed and feeding green feed can promote the rehabilitation of the disease.