Footrot Data Sheet Schmid et al., 2022

A national control program for virulent footrot is currently planned in Switzerland.
Since commonly used disinfectants either contain heavy metals or are carcinogenic,
the aim of this study was to verify the effectiveness of an eco-friendly and noncarcinogenic
candidate disinfectant against aprV2-positive strains of Dichelobacter
nodosus. Additionally, the effect of the selective use of long-acting oxytetracyclines was
evaluated. A total of 18 farms with confirmed footrot infection, randomly allocated to two
treatment groups: (1) with antibiotics (AB; n = 9) and, (2) no antibiotics (NAB; n = 9), were
included. Claws were carefully trimmed and scored using a scale from0 (clinically healthy)
to 5 (complete loss of the horn capsule) and a prewash waterbath was implemented
on 11 farms. Twice-weekly, repeated whole-flock stand-in footbaths with the candidate
disinfectant (6%) were performed. Additionally, animals of group AB with a score ≥ 3 were
administered oxytetracyclines by injection. On all farms, at 10 days after last treatment,
aprV2-positive strains could not be detected by risk-based sampling for real-time PCR
analysis after 7–21 (median = 12) footbaths with a minimal culling rate of non-responders
on nine farms. Farms without contact to other sheep remained without clinical signs of
footrot for a minimum of 245 days (mean ± standard deviation: 293.6 ± 23.6). Antibiotic
treatment did not reduce the number of footbaths needed. In contrast, a mean of 3.3
disinfecting footbaths could be saved by implementing a prewash waterbath. At animal
level, individual and selective use of oxytetracyclines lead to a higher chance (odds ratio
= 9.95; 95% CI: 3.54–27.95; p < 0.001) for a lesion score ≥ 3 to improve to a lesion
score < 3 within 2 weeks compared to treatment without antibiotics. The test disinfectant
is an effective and eco-friendly alternative for the planned Swiss footrot control program
and selective use of oxytetracycline has a beneficial impact on the recovery of animals
with lesion scores ≥ 3.