29 August 1997

ANIMALS OWN WORST ENEMIES FOR DISEASE

When it comes to identifying the greatest disease carrier and risk to health on farm, producers need look no further

than their own stock.

Rebecca Austin reports

Cattle

"THERE is no doubt the greatest enemy of beef cattle is another beef cow," says Roger Blowey, from the Gloucester-based Wood Veterinary Group.

"Any cattle brought onto the farm should always be isolated. But there is no point in just isolating an animal and doing nothing about it. Phone up the vendor and check the health status of his farm. Isolate the new animal for a month and then monitor to make sure it doesnt go down with anything nasty. This is quite common practice on pig farms, but relatively infrequent with cattle."

Salmonella typhimurium DT104, which causes abortion, is an increasing concern in beef and dairy cattle, says Mr Blowey. It is found in faeces on walls, in the corner of sheds and in the foot wells of farm vehicles. Basic cleaning is not enough to eradicate it. The only solution is formaldehyde fumigation.

Clean, secure feed storage prevents salmonella, which is carried by rats, mice and birds.

Digital dermatitis can be avoided by individually spraying feet followed by an antibiotic footbath. As there is a high risk of introducing this disease, Mr Blowey insists producers make the effort to do this.

Mange, which manifests itself as crusty and scabby legions, is cheap enough to treat, says Mr Blowey. "But again, check the source of infection."

Water-borne diseases can be avoided by providing a troughed water supply. "Johnes disease has now almost been eradicated where adult cows and calves are unable to drink from the same muddy stream," says Mr Blowey.

Johnes disease only shows itself in the first two months of life, but is carried by adult stock which pass it on – usually when calves drink from teats contaminated with faeces.

Leptospirosis is also carried in water and can contaminate cattle when infected stock urinate up- stream. Fencing off rivers and streams avoids this concern.

Reducing the risk of TB means looking after badgers already on the farm. "The best thing you can do is look after any badgers on the farm to avoid a TB-infected badger taking up residence in a vacant sett," advises Mr Blowey.

"But try and reduce the chance of contamination. This can be done by providing straight-sided water troughs which have at least 2ft sides. Always feed cattle off the ground and secure feed stores because it is more likely to be the diseased badger which is looking for an easy feed. Fence off crossing points through hedges to encourage badgers to the edge of the field and do the same to their latrines."

For dairy cows, the fly is the most common source of disease. During the summer it is responsible for outbreaks of summer mastitis and New Forest disease. At the same time, flies irritate cows, prevent them grazing properly and so, in turn, depress yields.

Electric fly killers are now common in most big parlours. Pour-on fly treatments are also effective, and should be squirted onto the back to cut down flies, advises vet Clive Norrell from The Malt House Surgery, Minsterley, Shropshire. "That should keep off flies for eight weeks, but I recommend repeating it monthly."

Summer mastitis can be avoided by using antibiotic dry cow tubes at drying off. In some cases heifers are also treated, but Mr Norrell recommends only doing this if there has been a problem on farm previously.

"This is also a bad year for husk," warns Mr Norrell. "Treat immediately because often coughing cows are not treated quickly enough and before you know it a lung worm infection has developed into pneumonia."

Sheep

Sheds harbour coccidiosis and viral scours. Disinfecting them helps, but when coccidiosis has been a concern, the only effective solution is oocide.

David Stoakes, a partner with the Ledbury-based Griffiths & Stoakes veterinary practice, recommends producers vaccinate against all eight of the soil-borne clostridial diseases which include black udder and pulpy kidney.

"Pasturellae are passed on by other sheep. Experience will show whether it is necessary to vaccinate against any of these," says Mr Stoakes. "The same goes for Border disease which causes abortion. This is often introduced when infected stock are bought in."

Sheep scab is caused by a mite, and as it can survive for two weeks in the environment, treated stock should not be returned to infected fields or transported during that period. And any new stock, or those returning from market, should be treated with an approved product on arrival.

Pigs

Most pig producers control pests reasonably well, says Jim Morris, practicing with the Haven Veterinary Group based at Hedon, Hull.

However, rats, mice, starlings, pigeons and flies are a common source of infection. Pigeons specifically introduce erysipelas, a bacteria which causes abortion, but vaccination avoids an outbreak. Vermin which travel between units are well know for carrying salmonellas and E coli, and hedgehogs can often be tracked down as the source of a leptospirosis outbreak.

Outdoor units are more susceptible to disease breakdowns as foxes, crows and seagulls mix with stock. The latter can be a serious risk when carrying sewage on its feet. And producers should be aware that swine fever – currently gripping EU pig herds – could easily be introduced by picnickers feeding Danish bacon sandwiches to outdoor pigs.

"Like all other livestock, the greatest risk is posed by the pig," says Mr Morris. "But vets and feed reps are also a source of infection – especially as they dont often have the cleanest wellies." &#42

REDUCING RISKS

&#8226 Isolate new stock.

&#8226 Check disease status.

&#8226 Ensure good hygiene.

&#8226 Control vermin.

&#8226 Treat promptly.

Any cattle brought onto the farm should be isolated for a month and monitored to ensure they dont go down with anything, warns vet Roger Blowey. Producers should also check the vendors farm health status.