Innovative Vaccines

There are two vaccines that we give to cattle that are unique in the way that they work. One protects against a parasite and the other against a fungal disease. These are pioneering products where some scientist has looked at a disease, worked out how calves respond to it and used that knowledge to come up with a solution to a problem. The lungworm vaccine for cattle was developed in the nineteen sixties at a time when the available wormers were poor compared to the drugs that we use today. Husk was a real problem then in calves turned onto pasture for the first time. Often the only real solution was frequent drenching and pastures rotation so that they went out onto ground that was not contaminated by the worm larvae.

Complicated Life Cycle

The life cycle of the parasite had been known for some time, but it was never thought that it would be possible to culture sufficient numbers of the L3 larvae so that they could be exposed to a measured dose of radiation that allowed them to make their way into the lungs of the calf and set up an immune response but not develop into the adult worms that caused the disease. It was never thought that it would be possible to organize a distribution chain that would get two doses of this fragile vaccine to the farm before the one thousand or so larvae in each bottle perished and the effectiveness was lost.

Different Disease

Until ten years ago lungworm was always considered to be a problem for young cattle. It was only under exceptional conditions, such as when adult animals moved from the drier part of the country where they had never been exposed to the larvae to the wetter areas that adult cows were seen to cough in the summer. Anthelminctics had become so efficient that many young animals were continuously protected when at pasture so no worm larvae were able to move through to the lungs and build up a natural immunity. At this time many dairy farms understandably abandoned the lungworm vaccine before turnout because they had found another way of controlling parasites in young calves.

Number of Outbreaks

Up until 1995 the number of lungworm outbreaks investigated by the Veterinary Laboratories Agency remained static each year at less than one hundred. Two years later they were regularly seeing five or six times that amount. These are distorted figures as many cases of this disease are diagnosed by clinical signs alone so the true figures are many times higher. By now the disease had changed, it was young adult cows that were coughing as it is only when they start their productive life that they are left to cope without the support of regular anthelminctics. In recent years the wormers have changed again and we have come to realize the advantages of worming dairy cows once an easy to use product that did not have a milk with hold time was developed. On these farms there may never be sufficient lungworm larvae on the pastures to cause clinical disease and you might not need to use the vaccine. If your worm control is less vigorous you need to consider that at some stage there is a need to get your stock immune to lungworms. It is easier to do this when they are calves as we are no longer accustomed to dosing large numbers of adult animals by mouth.

Stocked at the Surgery

The distribution system for the vaccine has now changed. It is now more stable and has a longer shelf life so this year it will not arrive by courier but come at the same time as our other drugs. There is still a need to keep Bovilis Huskvac in the fridge and to give a second dose after an interval of one month. We will keep track of the second dose and make sure we have sufficient stocks for you to complete the course two weeks before the calves go out to pasture. Bovilis Huskvac is an essential vaccine on organic farms as it is the only permitted way to control the disease.

The Only Fungal Vaccine

A vaccine for ringworm was not developed until about ten years ago. Ringworm is more than a cosmetic disease for calves. It certainly spoils the look of your animals and can be a real nuisance if you want to sell young stock or newly calved heifers as it does have a tendency to break out at times when animals are under stress and most buyers are reluctant to bring infected animals onto their farms. Because it causes animals to rub they will never do as well as un affected stock. Sometimes young calves will get lesions over the whole surface of their body. It had long been realized that most animals seem to get ringworm only once so they must build up an effective immunity to th

e fungus.

Helpful for Treatment

This again is a live vaccine that is better given before animals show any signs, although it does work when animals are already infected to clear up the lesions. Most of the effective anti fungal drugs that you were familiar with in the past have now lost their product license. It is very difficult to disinfect against ringworm in buildings as it is a robust organism that sheds spores and is difficult to kill off either with heat or chemicals.

Ringvac is still, as far as I know, the only vaccine in the world developed against a fungal disease. It can be given to any age of cattle, but is usually administered to calves as the dose is doubled for older animals.

Susceptible to Insects

It is very common for cats and dogs that live in houses to have fleas and most animals will get bitten at some stage of their lives. What is more difficult to understand is that when several animals live in the same house there will be one or two animals that the fleas are particularly attracted to and others where it is difficult to find traces of the parasites. New research undertaken at Rathamstead has demonstrated that some cows are particularly prone to being bitten by biting flies in the summer and others escape unscathed. By observation it has been shown that if the few animals that attract the flies are removed from the group than the rest will not be bothered by the insects. It is still not certain which chemicals attract the flies, but it is hoped that if a compound can be found to neutralize the smell it will be a lot easier to control flies on cattle during the summer months.

Sheep and Minerals

Sheep do not have the same requirements for minerals as cattle and sometimes it is easy to give them more than they require. The ones that cause problems are magnesium for male animals as the excess can precipitate in the urine and block the urethra of growing lambs and rams.

Also some breeds especially Texels can be very sensitive to the amount of copper in their ration. Take care particularly if they have had concentrates for a long period. It will cause liver damage.