Open Label, Multi-Arm Randomized Clinical Trial Evaluating Vitamin E-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 it has impacted the captive breeding colony for the eastern indigo snake (Drymarchon couperi) reintroduction program. This study investigates a novel treatment of GC in the eastern indigo snake. Seventeen eastern indigo snakes with GC were randomly divided into three groups: A, B, and C. Group A (n = 6) snakes received parenteral administration of 25 mg/kg of vitamin C, 0.5 mg/kg of vitamin E, and 50 μg/kg of selenium and 5 ml/kg of 3% hydrogen peroxide (H2O2) gavage; group B (n = 6) snakes received the same injections, but 5 ml/kg of water gavage; and group C (n = 5) snakes received no treatments and served as the control. All eastern indigo snakes from groups A and B tested negative for C. serpentis for 3 months following treatment, whereas only 60% (3/5) of snakes in group C tested negative. Eastern indigo snakes testing negative received one 4-mg/kg dexamethasone sodium phosphate injection. For 3 months following dexamethasone, 66.7% (4/6) of snakes in group A continued to test negative, compared with 83.3% (5/6) of snakes in group B and 20% (1/5) in group C. Eastern indigo snakes testing negative underwent gastric biopsies, but only one snake 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 and selenium without H2O2. The parenteral use of 25 mg/kg of vitamin C, 0.5 mg/kg of vitamin E, and 50 μg/kg of selenium once weekly cannot be recommended for treatment of C. serpentis in eastern indigo snakes if complete resolution of the parasite is desired.Abstract
Treatment evaluation flowchart describing evaluation of eastern indigo snakes (Drymarchon couperi) following the 10 wk of treatment. Each snake was evaluated for shedding of Cryptosporidium serpentis by quantitative polymerase chain reaction (qPCR) of cloacal swabs collected monthly for 3 months. Snakes testing positive at any time point were considered treatment failures. If a snake tested negative for three consecutive months, it was immunosuppressed with 4 mg/kg SC dexamethasone sodium phosphate (Dexamethasone-SP, 4 mg/ml, VetONE) and retested for shedding of C. serpentis by qPCR of cloacal swabs collected monthly for an additional 3 months. Snakes that continued to test negative were subjected to gastroscopy for visual evaluation of gastric mucosa and biopsies for histologic and molecular analyses.
Feeding chart with description of response of eastern indigo snakes (Drymarchon couperi) to feeding for groups A, B, and C. Snakes in each group were offered a meal twice weekly throughout the study, and the response to each meal is annotated as follows: A = ate; R (highlighted orange) = refused meal; and V (highlighted red) = vomit/regurgitation. Weeks of the study are along the x-axis: 1–10 (blue) = treatment period; 14, 20, 23, 28, 32, 35 (green) cloaca swabbed for Cryptosporidium serpentis quantitative polymerase chain reaction; 27 (pink) = dexamethasone sodium phosphate injection (Dex-SP), 40 (gray) = gastroscopic biopsy (Bx). Snake C1 died during week 18 of study. Total meals refused and total number of regurgitations are summarized below each group.
Correlation of clinical signs. Pearson correlation (ρ) between demographics and clinical signs associated with the gastrointestinal (GI) system in eastern indigo snakes (Drymarchon couperi). Perfect correlation, ρ = 1.00; very high positive correlation, ρ = 0.90–0.99; high positive correlation, ρ = 0.70–0.89; moderate positive correlation, ρ = 0.50–0.69; low positive correlation, ρ = 0.30–0.49; negligible correlation, ρ = 0.30 to −0.30; low negative correlation, ρ = −0.30 to −0.49; moderate negative correlation, ρ = −0.50 to −0.69; high negative correlation, ρ = −0.70 to −0.89; very high negative correlation, ρ = −0.90 to −0.99. BW = body weight; SVL = snout-to-vent length; BCI = body condition index; LOI = length of infection; GI = gastrointestinal; pre-tx = pretreatment; tx = treatment; post-tx = posttreatment; post-dex = postdexamethasone.
Summary of quantitative polymerase chain reaction (qPCR) results in eastern indigo snakes (Drymarchon couperi) undergoing treatment for gastric cryptosporidiosis. Group A snakes received injectable vitamin E (Vit E) plus selenium (Se), injectable vitamin C (Vit C), and 3% hydrogen peroxide (H2O2) gavage. Group B snakes received injectable Vit E plus Se, injectable Vit C, and water gavage. Group C snakes did not receive any injectables or gavage. Dex-SP = dexamethasone sodium phosphate injection.
