Hepatogenous photosensitization in ruminants and horses caused by the ingestion of Chamaecrista serpens in Brazil.

The research paper investigates the first reported incidents of liver-originated photosensitization in cattle, sheep, and horses in Brazil due to the accidental consumption of a plant, Chamaecrista serpens, and the reproduction of similar effects through experimental studies.

Study Background and Objectives

• The study was primarily targeted at describing the novel findings of eleven outbreaks of liver-originating photosensitization (photosensitivity initiated due to liver disease) occurring in cattle, sheep, and horses. These outbreaks were associated with the ingestion of Chamaecrista serpens; a wild plant, commonly found in the semiarid region of Bahia, northeastern Brazil.
• The research also aimed at experimentally reproducing the effects of such poisoning in sheep to verify the observations and findings from the field.

Study Methodology and Observations

• The photosensitization triggered skin lesions, which showed progressive symptoms like hyperemia, edema, the creation of ulcers and necrosis. These effects were typically observed in areas of non-pigmented skin and seemed to be more severe in younger animals.
• In addition to physical symptoms, altered behaviors were observed, such as the animals avoiding sunlight and displaying signs of restlessness, irritability, severe itching, along with decreased appetite and weight loss.
• Experimental research was further conducted on seven sheep, which developed photodermatitis similar to the symptoms observed in natural poisoning, seven days after consuming the plant. The remaining two sheep were used as a control group to draw comparative conclusions.

Serum Biochemistry Changes and Necropsy Insights

• The biochemical changes in the serum indicated liver damage from the plant ingestion. Skin and liver biopsies were performed, including an ultrasound-guided liver biopsy.
• About one sheep with severe skin lesions was euthanized, upon whose necropsy, the liver was found enlarged and firm, with a distinct lobular pattern and an empty gallbladder, indicating the extent of the liver damage.
• Further histopathology examinations on the liver revealed extensive necrosis and degenerative changes. The skin was observed to have orthokeratotic hyperkeratosis, hypergranulosis, acanthosis with large areas showing necrosis and ulcers.

Summary and Conclusion

• Following the cessation of the plant’s consumption, three sheep, which were kept away from direct sunlight, showed regression of skin conditions within 45 days.
• The study concluded that the consumption of Chamaecrista serpens leads to hepatogenous photosensitization in ruminants and horses. Hence, it must be considered as a differential diagnosis for photosensitive dermatitis events in these animals.