Respiratory Diseases- Better to prevent than to cure
Respiratory diseases without doubt cause more deaths in young growing cattle in this country than any other disease. The most common respiratory diseases in housed cattle are the different forms of pneumonia. Pearse Kelly, Teagasc Head of Drystock, details why prevention is better than cure
Respiratory diseases without doubt cause more deaths in young growing cattle in this country than any other disease. An Irish study a number of years ago that looked at the health of over 6000 cattle in slatted units found that respiratory diseases were by far the main cause of ill health and death over a six month housing period. The most common respiratory diseases in housed cattle are the different forms of pneumonia.
There are a number of different types of pneumonia that are regularly found on Irish farms to cause a problem. The most common of these are RSV, PI3 and IBR. All of these are viruses that are transmitted by close animal to animal contact through the air. Once an animal becomes infected with one or more of these viruses they become much more susceptible to secondary bacterial infections that can cause them serious damage.
Cost of an Outbreak
When trying to estimate the losses incurred due to a respiratory disease outbreak a cost must be put on the loss of animals, the cost of treatment and the loss in lifetime production due to it. One study put the potential cost of treating an individual calf for viral pneumonia as high as €136.
Putting a figure on the cost of an outbreak of pneumonia within a group of animals is not as easy i.e. some calves may not need to be treated intensively but their performance is definitely affected. One study that looked at the losses incurred in beef herds affected by a pneumonia outbreak examined them under the headings of weight loss, labour costs, veterinary costs, mortality and the cost of medicines put the overall cost at €110 per calf in the whole group.
Most Risk at Housing
If the conditions are suitable a pneumonia outbreak can occur at almost any time of the year. However, it is at housing that most farmers have a problem with it. This can be for a number of reasons. Stress is the biggest pre-disposing factor involved. Where stock are stressed their immune system is weakened allowing the infection to take hold. Animals can become very stressed at housing especially if they are mixed with cattle from different groups.
The mixing of purchased cattle from different farms or different age groups in its’ self can lead to respiratory disease problems as the infection spreads to animals that might never have come across the infection and so have little or no immunity towards it. They do not have to be in the same pen to be considered mixed, only the same air space. With large slatted units on many farms now housing many different groups of cattle it can be next to near impossible to avoid this happening.
As pneumonia is an air-borne disease it will spread much more easily in confined spaces. Add to this poor ventilation and overcrowding and the problem is further compounded. There must be adequate inlet and outlet ventilation to allow fresh air movements through cattle housing and adequate lying space, otherwise the first night with little or no wind outside could spell disaster.
When a pneumonia outbreak occurs in a herd there is usually a fire-brigade type response to it. Unlike with a fire though, it is rarely stopped immediately. That is why the costs mount up. Apart from the cost, a pneumonia outbreak can be very stressful for the farmer involved. Virus pneumonia affects the best calves in a herd just as much as the worst calves. It takes a lot of effort and time to get a group of animals back on track. With more and more drystock farmers now working off the farm it is not always possible to give this amount of time. By far the best approach all round is to avoid a pneumonia outbreak in the first place.
Management procedures such as castration, weaning and housing all cause a significant amount of stress. Don’t carry out all of these at the same time. Try to space them out over a number of weeks. When weaning always take a proportion of the cows away from the calves each week until they are all gone. By doing this the calves are left in their familiar surroundings. By feeding meal to the calves the stress of weaning should be kept to a minimum.
One of the best routes for preventing a costly pneumonia outbreak in young stock is to vaccinate against the main viruses involved. Once again though, a certain amount of planning must go into this. By vaccinating an animal against any disease you are stimulating its immune response to produce antibodies against it. Most vaccination programmes involve giving a two shot programme to stock when they are vaccinated for the first time. A small amount of immunity is generated by the first vaccination treatment but this will quickly wane and it is only after the second (booster) vaccination, given three to four weeks after the first (primary) vaccination, that the full degree of long term immunity is built up to the disease. After this, single booster vaccinations are usually recommended when vaccinating the same animals 6 to 12 months later (depending on the product used). Live intranasal vaccines are a one shot programme that act within 7-9 days but only give protection for 3 months.
To have full cover against the most common pneumonia virus’s cattle must therefore be started on the vaccination program well in advance of when they need it most. Housing of course poses the biggest danger and having full cover by then is essential.
Housing Tips – To avoid Pneumonia
- Check ventilation – is it adequate or will you need to improve it?
- Check lying space allowances – is there enough or do you need to reduce the numbers in pens
- Watch out for hoose at this time of the year – a severe infection weakens the lungs and makes an animal more susceptible to pneumonia. All cattle should be treated for it shortly after housing.
- Try not to house cattle of different age groups close to each other.
- Keep bought in cattle separate to home bred cattle for as long as possible.
- Have young cattle used to eating meals and silage before housing.
- Ideally implement a pneumonia vaccination programme well in advance of housing (at least three weeks) to give time for the two shots to be given.
Frank O'Sullivan, Veterinary practitioner, Trim, Co. Meath emphasises the importance of prevention in this video where he demonstrates the damage caused by pneumonia in cattle lungs