One of the main causes of lameness in weaner deer is from a bacterium called Fusobacterium necrophorum.
This organism enters an abrasion or cut on the lower leg or foot and causes an infection which can lead to swelling and abscessation in soft tissue or joints and then lameness. The bacterium cannot penetrate intact skin.
Occasionally the bacteria cause mouth and throat lesions, stomach lesions in grain fed animals and navel abscesses in new-born fawns. It can cause spinal abscesses which can lead to partial paralysis of one or both hind legs. All infections lead to weight loss and in some cases, deaths are the first sign that disease is within the herd. Dead animals will have multiple abscesses in the liver, lungs or kidneys.
This bacterium survives well in manure-contaminated wet soil. One of the commonest entry points is through feet that have been damaged during yarding and trucking. Wet surfaces further assist penetration. Infections are more common in stressed deer – following transport, yarding, weaning or bad weather.
Early cases of F. necrophorum can be saved by injectable antibiotics, together with cleansing and dressing the affected feet. Easier said than done. If the infection has spread to the liver, lungs or kidneys then treatment is usually futile. If a few deer show signs of the disease then treating all the animals with antibiotics in the herd maybe the advice given to help prevent infection spreading.
There is no licensed vaccine for the disease. F. necrophorum is present in the environment so preventing it from entering the body and practising good hygiene in stock handling areas is key.
In races, gateways, yards and handling facilities: remove sharp stones/concrete and objects (nails, wire etc); board yards and cover fences in yards to prevent feet catching between boards or in fencing; keep yards as clean as possible and minimise water pooling (provide good drainage); eliminate slippery surfaces (rubber mats); clean floors regularly to remove dirt and faeces and periodically disinfect; minimise time in yards.
Other prevention strategies include: using clean weaning paddocks; avoiding pressure points in laneways; running small mobs; minimising yarding and mustering around weaning; implementing weaning strategies to minimise fence pacing; and keeping weaners away from wire netting. Before transporting deer ensure the floor surfaces in the truck and loading race are clean and intact. When deer arrive at your property keep them separated for 10 days to make sure none has developed lameness or any other disease.
Anecdotally, some farmers have noticed reductions in lame weaner deer using foot baths or mats containing formalin, zinc sulphate or copper sulphate but a study using formalin foot baths could not demonstrate this reduction. Anecdotal evidence from industry and farmers suggests management and prevention by the above strategies are more effective in reducing the number of lame weaner deer.