The Relationship Between Duck Photosensitivity and Fluoroquinolone Drugs

Duck photosensitivity refers to a disease in which ducks, after ingesting substances that cause photosensitivity, develop blisters or ulcerative symptoms on the epithelium of the upper bill and webbed feet due to exposure to ultraviolet radiation from sunlight. The disease is characterized by deformation of the upper bill and webbed feet, shedding of the keratinized layer, and conjunctivitis of the eyes.

I. Clinical Symptoms and Pathological Changes of This Disease

This disease can be seen in ducks of all breeds, with the age of onset tending to be younger, occurring in all age groups after 10 to 20 days of age; the incidence rate varies, and the mortality rate is generally low (if secondary bacterial or viral infection occurs, it can cause a high mortality rate), with a high rate of culls and poor market appearance. At the onset of the disease, hemorrhagic spots or blisters appear on the dorsal surface of the upper bill and the dorsal surface of the webbed feet, which gradually enlarge and eventually rupture to form scabs; after about 10 days the scabs fall off, revealing pink or brownish-yellow ulcers. As the disease progresses, the upper bill begins to deform and shorten, or turns upward and outward; in severely affected individuals, the tip of the tongue protrudes, affecting feeding; the eyes water, the conjunctiva becomes inflamed, and in severe cases adhesion occurs. If there is no secondary infection, no other visible lesions are found in the internal organs except for an empty digestive tract.

II. Causes

1. The feed composition contains seeds of certain plants (such as large borage seeds) and root tubers (such as Sichuan lovage root tubers), etc. These substances are rich in photosensitizing substances or fluorescein. After ducks consume feed containing these substances and are exposed to continuous outdoor sunlight for a period of time, the disease can be triggered.

2. According to Guo Yupu's report, ducks ingesting excessive amounts of quinolone drugs can also induce similar symptoms of this disease. In addition, it has been found that duck flocks living for a long time in water sources seriously polluted by chemical substances can also develop similar symptoms of this disease (this may be related to corrosive chemical substances).

Recently, duck photosensitivity reactions have occurred frequently. A characteristic is that this disease mostly appears during the treatment or recovery period of other diseases, and there is a history of fluoroquinolone drug use. There is a causal relationship in certain respects between the use of fluoroquinolone drugs and duck photosensitivity reactions, that is, what is the connection between the use of fluoroquinolone drugs and photosensitivity? For a long time, people have conducted extensive in-depth research on this class of drugs from various aspects. Fluoroquinolone drugs, because of their powerful and unique antibacterial effects, play an important role among antibacterial drugs and are widely used in clinical practice. However, the adverse reactions of this class of drugs, such as photosensitivity reactions, drug rash, skin itching, burning sensation, and effects on the metabolism and development of animal cartilage tissue (especially serious in young animals), are specifically emphasized in the pharmacology of this class of drugs. In addition, according to Xie Bin's report, animal experiments have found that fluorine can damage the cartilage of young animals. As everyone knows, an appropriate amount of fluorine is beneficial to the animal body, while excessive fluorine is harmful to the growth and development of the animal body. The molecular structures of fluoroquinolone drugs all contain one or more bound fluorine atoms. Perhaps it is precisely the fluorine contained in the molecular structure of this class of drugs that may be an important factor causing metabolic and developmental disorders of animal cartilage tissue and photosensitivity reactions. The bill and webbed feet of ducks both contain cartilage tissue, and the younger the age, the richer the cartilage tissue in the bill and webbed feet (the same is true for bone tissue). Therefore, the cartilage tissue in these parts is also most susceptible to damage by fluorine. At the same time, the damage caused by intense sunlight ultraviolet radiation to epidermal tissue is definite. The tender epidermal tissue of the duck's bill and webbed feet is exposed; the younger the age, the more fragile these epidermal tissues are, and the most susceptible to ultraviolet damage. Precisely because of this, the damaging effects on the skin and cartilage tissue are mutually intensified and aggravated, and as a result the duck's bill and webbed feet are the first to be damaged, leading to the appearance of related symptoms. Interestingly, actual clinical practice has also found that duck flocks with photosensitivity or similar symptoms are generally most commonly seen in the 10 to 30 day age range, and the younger the age, the more severe the disease; moreover, most of these duck flocks that develop this disease had a history of treatment with fluoroquinolone drugs (such as for serositis and colibacillosis) before the onset of this disease; in summer, the use of difloxacin hydrochloride, levofloxacin, lomefloxacin, etc. can also very easily lead to the occurrence of similar photosensitivity reaction symptoms in ducks. According to Guo Yupu's report, ducks ingesting excessive amounts of quinolone drugs can also induce similar symptoms of this disease. From this it can be foreseen that the side effects of fluoroquinolone drugs on ducks (especially young ducks) are twofold: (1) the risk of photosensitivity reactions; (2) effects on duck growth (mainly caused by metabolic and developmental disorders of duck cartilage tissue). If phosphorus and calcium sources with excessive fluorine are used in the feed, it may aggravate the side effects of fluoroquinolone drugs on ducks, and users should pay attention to this (especially in seasons with strong sunlight). From this it appears that, apart from being related to sunlight ultraviolet radiation, there is a causal relationship between the use of fluoroquinolone drugs and duck photosensitivity reactions, but whether it is related to the fluorine contained in the molecular structure of this class of drugs remains to be studied.

III. Diagnosis and Prevention and Treatment

This disease can be accurately judged based on clinical features. Avoiding contact with various factors related to this disease (especially intense sunlight exposure), supplementing sufficient amounts of vitamins A, D, E, C, and niacin, raising the amino acid level in the feed, and feeding green feed can promote recovery from this disease.