Bird Flu
Avian influenza is a highly contagious infection that was first recorded in domestic fowl in Italy more than 100 years ago. It is caused by the Type A Influenza virus that can occur as different strains. From time to time there have been outbreaks of bird flu throughout the world notably in the United States in 1924 and again in 1929 and 1983-84. On each occasion it has been eradicated by slaughtering affected flocks, but somehow it survives in a milder form in the general bird population and keeps coming back. It was last seen here in 1992 in a flock of 8,000 eighteen week old Turkeys in Norfolk. All of these birds were slaughtered and there was no spread of the infection to neighbouring farms or suspicion of the disease recurring since.
Different Strains
At the moment there is a highly pathogenic form of the virus called H5N1 that has spread from south East Asia through China to Russia. This form of the disease is known to be pathogenic to people and so far at least 120 human cases have been documented of which more than half have died. All of the cases so far have been from people who have direct contact with infected poultry. The fear is that should the virus infect a person who had the human flu virus the infection would be able to mutate and spread to other people. This must be a real fear as so far the government has ordered 100 million pounds worth of Tamiflu the anti virus drug. It is not clear as to how effective this drug is at preventing the spread of the disease.
Clinical Signs
This is a difficult disease to diagnose. In poultry the first signs are swelling of the head and the wattles and comb tends to go blue. Diarrhoea and a drop in eggs
Production is also reported to occur. Within 48 hours of the disease getting established in a flock there will be significant losses.
In the above picture the bird on the left has avian influenza
Signs in other Birds
I have not been able to discover much about the symptoms in other birds. The danger is that other bird species do not seem to be so adversely affected by this virus and can carry it whilst showing few symptoms of disease. If it is brought here by migrating birds the infection will first spread in the wild bird population, these individuals will not necessarily drop dead out of the sky. As far as I can determine nobody is looking for the first signs of the disease and we will not necessarily be aware that it is spreading amongst the pheasant or backyard poultry flocks until significant losses have occurred.
If you find any dead birds of whatever species please contact the surgery so that we can arrange for a full post mortem to be undertaken.
Cattle Poisons
Sometimes cattle go out of their way to poison themselves. An incident this week end illustrated just how vulnerable they are. Somebody was doing a good turn for a neighbour and offered to burn a trailer load of garden waste because of the high cost of it going into a skip. This was taken to a corner of a field and burnt. Unfortunately a group of store heifers who had several fields to graze discovered the smoldering fire and investigated the tip. The next day one animal was found dead on the field and another was down and soon died. The rest of the group was immediately moved into a building. At this stage there was very little left of the garden rubbish, a search amongst the ashes revealed two yew leaves and some smoldering wood. Yew is very toxic to cattle as little as three leaves has been known to kill a cow. They will not usually eat it from a tree, but they will readily find it once it is cut or if a branch should come down is rough weather.
Cattle should never have access to places where you have burnt wood or plastic. Wood from buildings can sometimes have paint or preservative residues in it that contains lead that gets concentrated into the wood ash. Spent engine oil, grease and discarded batteries are all a source of lead that cattle will actively seek and consume.
Strategic Worming
Although it has not been dry all of the time for most of the summer worm larvae have been trapped in the cow pats and in the soil as the grass has been too dry for them to survive on it. It was an early spring and any young cattle given a worm bolus should have done well, but the bolus will be starting to wear out now. As soon as it rains in September we can expect a surge in the worm challenge as the larvae that have been dormant in the soil throughout the summer are activated again. This is a good strategic time to worm young stock to take them through to the end of the grazing period.
Problems with Orf
Orf seems to come and go in cycles. This summer we have seen a bit of an upsurge in the number of cases in growing lambs and replacement ewes. This might be partly because there is now only one company who produces the vaccine to prevent Orf and unfortunately they had supply problems in the spring at the time when most of you wanted to use it. I have certainly noticed lambs with Orf at local markets and understand that a worker at an abattoir has the infection on one of his hands.
Sometimes older sheep show only mild symptoms on their lips and nose, the problem is the infection tends to go on for a long time and some of the ewes will get small lesions on their teats which lie in wait to infect the lambs when they first suck.
Orf and Thistles
Thistles make Orf worst at this time of the year as it takes the infection deeper into the skin and can start up a secondary bacterial infection. I would have thought that ewes with sore mouths would be wary of eating close to thistles, but this does not seem to be the case. Orf can also be a problem in lambs that you want to take to shows as even the smallest lesion is enough to stop them going. The best solution to Orf is to vaccinate the whole flock with the scratch vaccine so that they will build up a sound immunity and shed all of the lesions before next season's lambs. If the lesions are very inflamed and infected antibiotics both topically and by injection may also be needed.
Scouring Calves
Calves often get digestive upsets sometimes because they have picked up an infection but often because they have had too much milk. In the recovery phase to re establish the bacteria in their digestive tract try the now popular yogurt drinks. They seem to help calves and foals recover from digestive upsets.