Individual study: Treatment of foot rot in free-ranging mouflon Ovis gmelini populations in the federal states of Hessen and Rheinland-Pfalz, Germany
Volmer K., Hecht W., Weiß R. & Grauheding D. (2008) Treatment of foot rot in free-ranging mouflon (Ovis gmelini musimon) populations; does it make sense? European Journal of Wildlife Research, 54, 657-665
The aim of this study was to assess whether it is possible to control foot rot (caused by the pathogens Dichelobacter nodosus and Fusobacterium necrophorum) in introduced mouflon Ovis gmelini musimon populations in Hessen and Rheinland-Pfalz (Germany) through a combination of capture, treatment and release measures. This has important conservation implications as foot rot disease is endemic in many wild populations.
Study populations: Three free-ranging mouflon populations (Hinterland, Vogelsberg and Donnersberg) were studied between 1994 and 2005. A fourth population (Laubach) was observed from 1981 to 2005; in 1986, this population was affected by foot rot but no treatment was undertaken; it was used to compare population trends with those in which treatment was performed.
The first foot rot incidents were noted in the late 1980s and early 1990s in the Hinterland and Vogelsberg populations, and in 1999 in the Donnersberg population. Initial outbreaks resulted in extremely high morbidity (>95%) and high mortality.
Field data were collected by local mouflon experts. Body condition and clinical data were obtained by the authors during catching and treatment.
Foot rot control scheme: The scheme involved three measures:
i) protection of mouflon from the introduction of foot rot pathogens by free-ranging domestic sheep (carriers and vectors of the disease); foot rot incidences started a few weeks after sheep herds first entered submontane mouflon habitat in spring. Shepherds were unwilling to voluntarily avoid areas occupied by mouflon, therefore official restriction orders were necessary;
ii) the capture of as many mouflon as possible and vaccination;
iii) the treatment of mouflon that showed hoof abnormalities due to foot rot.
Mouflon capture, treatment and release: Two capture methods were used: a walk in 'kraal' baited with food, and net trapping. Caught mouflon were kept for about 6 weeks in a field corral (area 15,000 m²) during which treatment, including two vaccinations, were undertaken. Four to 6 weeks after treatments, a final check that hooves were completely intact was performed, and the animals were released.
In the three treatment areas, 275 mouflon (250 individuals in total; 25 caught more than once) were caught (100 in nets; 175 in kraals). A disadvantage of the kraals were that they were often occupied by roe deer Capreolus capreolus or wild boar Sus scrofa, which were attracted by the food. Disadvantages of net trapping were that manpower demands were high and caught mouflon had to be promptly extracted.
Prevalence of foot rot from field observations in the three treated populations was: 90% Hinterland, 50% Vogelsberg and 60% Donnersberg.
Numbers of caught individuals was: 90 (80 treated) Hinterland, 55 (35 treated) at Vogelsberg, and 105 (45 treated) at Donnersberg. Of these, 50 became re-infected during the course of the study in the Hinterland population; none became re-infected in the other two populations.
In April 1987, the Laubach population (untreated) comprised 44 mouflon. That summer a foot rot endemic occurred killing all but eight animals by October. It took 15 years for the population to recover to 40 animals.
Conclusions: The authors conclude that an efficient system of capture and treatment is crucial for foot rot control in mouflon, but acknowledge that this will be expensive. Selective shooting of all animals with clinical signs may also be required but hunters have to suspend hunting during the treatment period to avoid shooting of treated and vaccinated animals.
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