Description
Orf – a bigger problem than you think: ” Orf may be found in as many as 10% of sheep flocks in the UK ” Once a flock contracts Orf, the disease spreads rapidly among exposed groups in the flock. ” In severe outbreaks of Orf in nursing ewes and suckling lambs, it may be necessary to artificially feed the lambs. This is labour intensive and economically damaging. ” The direct mortality rate due to Orf is less than 1% but in cases that lead to secondary infections this rate increases dramatically to between 20 – 50% ” Outbreaks of Orf in a flock prevent sheep being marketed, slaughtered and being shown. ” The lesions of Orf are painful and cause much distress, particularly to ewes and suckling lambs. (Orf) in sheep Orf is a common skin disease affecting sheep and goats. It is a highly contagious disease caused by a virus in the “pox” family. The virus causes pustular and scabby lesions on the non-woolly areas of the skin and occasionally in the mouth and oesophagus. Orf is prevalent worldwide and all sheep flocks in the UK are potentially at risk as it affects all breeds of sheep. Orf is a zoonotic disease meaning animals can transmit it to humans. Transmission : In flocks that have never had Orf, nearly all exposed animals will be susceptible to the disease. The virus is transmitted to susceptible animals via direct contact, for example, through rough grazing. The virus penetrates through small abrasions in the skin. Even very minor damage to the skin may allow the virus to enter. Orf can be spread via infected equipment, fences, feed, and bedding. Clinical signs Once in the skin, the virus begins to multiply. About two to three days after exposure to the virus, vesicles, pustules, and finally scabs appear. Orf lesions occur primarily on the lips and nostrils of affected animals, but may also develop on other parts of the body: e.g. ears, eyes, feet, limbs, udder, and genital areas. Orf affects mostly non-woolly areas. While it can grow in the upper digestive tract of the animal, it cannot spread through the body. During the course of the disease (1 to 4 weeks) the scabs drop off and the tissues heal without scarring. Sometimes, the scabs harbor secondary bacteria (such as staphylococci) producing pus which may invite blowfly infestation. Lambs: Lambs sucking infected teats will become infected by Orf. Lesions in suckling lambs are most frequently seen around the mouth and nostrils. The pain caused by these lesions may prevent the lamb from feeding and it may cause death from dehydration and starvation. Grazing and finishing lambs may also develop Orf around their mouths. A rarer form of Orf, known as strawberry foot rot can occur where lesions develop on the lower part of the legs causing lameness. Lambs with either form of Orf may suffer reduced growth rates. Ewes: In ewes, lesions are commonly found on the udder and teats. This may result in acute staphylococcal mastitis leading to loss of udder function or death of the ewe. Ewes with painful lesions on the udder may also prevent their lambs from suckling which could lead to dehydration and starvation. Rams: A venereal form of Orf occurs in rams. Affected rams become reluctant to mate which disrupts the breeding season with a consequent long drawn out lambing. Treatment : Because Orf is a virus, Orf does not respond to antibiotics. Treatment of individual animals usually consists of applying anti-fungal salves to the lesions. Systemic antibiotics can be used if secondary bacterial infections are severe. Ewes, whose udders become infected, should receive special care. Udder cream will help to keep the scabs on the teats pliable. In worst cases, the lambs should be removed for artificially feeding. They should not be cross-fostered onto other females as they may infect the udders of clean females. Orf is rarely fatal but it will cause significant economic loss. Orf lesions are painful to the affected animals, especially young stock. While most adult animals with lesions on their lips continue to eat and produce milk, it may be too painful for young lambs to suckle or eat dry feed. Left unattended, these lambs will become undernourished and more susceptible to secondary diseases. It may be necessary to artificially feed such lambs.
