Open-label, Multi-arm Randomized Clinical Trial Evaluating Vitamin E and Selenium Injection, Vitamin C Injection, and Hydrogen Peroxide Gavage as a Treatment for Gastric Cryptosporidiosis in Eastern Indigo Snakes (Drymarchon couperi)

Gastric cryptosporidiosis (GC) is an insidious infection in squamates caused by the protozoan Cryptosporidium serpentis and has impacted the captive breeding colony for the eastern indigo snake (Drymarchon couperi; EIS) reintroduction program. This study investigates a novel treatment of GC in EIS. Seventeen EIS with GC were randomly divided into three groups: A, B, and C. Group A (n = 6) received parenteral administration of 25 mg/kg vitamin C, 0.5 mg/kg vitamin E, and 50 μg/kg selenium and 5 ml/kg 3 % H2O2 gavage; Group B (n = 6) received the same injections but 5 ml/kg water gavage; and Group C received no treatments and served as controls. All EIS from Groups A and B tested negative for C. serpentis for three months following treatment, while only 60% (3/5) in Group C tested negative.  EIS testing negative received one 4 mg/kg dexamethasone sodium-phosphate injection. For three months following dexamethasone, 66.7% (4/6) in Group A continued to test negative compared to 83.3% (5/6) in Group B and 20% (1/5) in Group C. EIS testing negative underwent gastric biopsies but only one from Group C was confirmed to be negative for C. serpentis. Although parenteral vitamin C, vitamin E, and selenium with H2O2 gavage decreased shedding of C. serpentis, it did not outperform the vitamins/selenium without H2O2. The parenteral use of 25 mg/kg vitamin C, 0.5 mg/kg vitamin E, and 50 ug/kg selenium once weekly cannot be recommended for treatment of C. serpentis in EIS if complete resolution of the parasite is desired.