DISCUSSION
This study reports the first field treatment trial using Tri-Solfen® as a therapy for the clinical management of FMD in Africa, comparing the clinical efficacy of this novel therapy with the commonly used parenteral antibiotic treatment Moore-Oxy® and animals remaining untreated. Despite necessary limitations due to resources availability on numbers of farmers and cattle recruited for the trial, the results and all participants, considered it was very successful, with high levels of appreciation by participants for their involvement and the clear results obtained.
Lesion healing scores across the three groups revealed superior results for the TS-treated cohort and although the MO-treated cohort also achieved a reasonable score, the untreated control animals had lesions persisting for in excess of 2 weeks. Although a subjective measurement, these scores provide a useful indication of the healing rate of FMD lesions in field conditions in Cameroon.
Similarly, appetite scores were highest in the TS-treated cohort, indicating that the treatment supported the rapid return of appetite, even after 3 days. Superior appetite scores in this group were recorded at each data collection between day 3 and day 15, with the cohort receiving treatment with MO also having reasonable appetite scores between days 3 and 15. The control cohort cattle had poor appetite scores throughout, indicating appetite remains poor for in excess of 2 weeks when FMD remains untreated.
Lesion size was measured (in cm) at six data collection intervals, with the FMD infected cattle lesion size decreasing rapidly in the TS-treated cohort. By day 6 this cohort was performing well with average lesion size at 0.33 cm, despite commencing in the trial with higher average lesion size. By day 9, the lesions in the TS-treated cohort had almost entirely disappeared, remaining at 0 cm through day 12 and 15. Interestingly, the control group average lesion size increased as the trial progressed. In the MO-treated cohort, the average lesion size decreased until day 12, where it was recorded to increase from 0.17 cm to 0.75 cm at day 15. Stage of infection may have affected the study here, particularly as the lesion size in the control cohort was 0 cm at trial on day 0.
The farmer observations of clinical impacts also provided interesting results which could be used as animal welfare indicators as well as indicators of clinical response to the treatments. The mobility of all 12 cattle in the TS-treated cohort returned immediately, suggesting this is a very useful therapy to enable cattle to walk and gain access to water and feed. In the MO-treated cohort, 10 of the animals also immediately returned to walking. However, of the control group, only five had immediate mobility and four animals did not return to walking even by day 15. There was one animal in the MO-treated cohort that did not return to mobility until day 12. In total, 7/36 (19.4%) cattle had not returned to mobility by day 9, indicating that FMD is a severe disease as it renders animals immobile and that although FMD is considered a low mortality disease, the animal welfare impacts are considerable.
As oral vesicular lesions can have significant impacts on animal behaviours, recording the number of days the animals were anorexic was considered important. In total, 11/12 cattle in the TS-treated cohort were reported to be eating the same day as treatment (day 0). This compared to 9/12 cattle in the MO-treated cohort, with only 2/12 in the control cohort, with 9/12 of these untreated cattle remaining anorexic until day 15. Further, salivation is a common clinical sign with cattle with vesicular disease, considered an overt indicator of oral lesions and presumably oral pain. In all three cohorts the majority of cattle had ceased salivating at day 0, with the TS-treated cohort achieving 11/12, MO-treated cohort 10/12 and the controls 8/12.
Farmer reports of visible lameness of trial cattle indicated that 9/12 cattle in the TS-treated cohort ceased any lameness at day 0, compared to 5/12 in the MO-treated cohort and 3/12 in the controls. By day 6, no further cattle in the TS-treated cohort showed any lameness compared to 5/12 cattle in the MO-treated cohort still showing lameness by days 12 and 15, with lameness only ceasing by day 15 in 9/12 control cattle. For the question of how many days prior to cattle returning to grazing, mixed results were recorded. In the control cohort, 9/12 were reported grazing by day 0, with 8/12 in the TS-treated cohort returned to grazing by day 3 and all 12/12 in the MO-treated cohort returning to grazing by day 6.
When asked for a broad overview of treatments applied to FMD, six options were provided, including antibiotic formulations, traditional drugs, insecticides and petrol. Without speculating on the therapeutic potential of each treatment, it does indicate that farmers and paraveterinarians are inclined to treat affected animals withsomething . The data on costs of treatment suggest there are only minimal differences between treatments and that cost should not be an impediment to changing of treatment choice.
Field studies involving animal treatments with assessments of clinical impacts are challenging and subject to potential bias, reflected in the limited published literature on FMD therapy. However, the results obtained in this study demonstrate the superior clinical efficacy of a single application to FMD lesions of the TS topical anaesthetic wound formulation. The participating farmers reported a 100% appreciation for the product in the treatment of FMD and expressed they were happy to have this product available for use in the region. These findings were consistent with those from a recently reported clinical investigation of TS therapy for FMD in Laos (Windsor et al, 2020) and reports of the use of this product for FMD in other countries in Africa, including Niger, Nigeria, and Kenya. This study in Cameroon provides the quantitative assessment that confirm that TS is efficacious in hastening clinical recoveries, immediately addressing pain and invoking more rapid healing of FMD lesions, as observed qualitatively in Laos (Windsor et al, 2020). As this innovation provides superior animal welfare outcomes for animals suffering from FMD, without the risks of AMR that arise from the more typical therapies in use for FMD globally, efforts to promote this new therapeutic approach should be supported.