Vaccinations are not an absolute protection

Gary Sliworksky
Ag. Rep.

With all the emphasis on vaccinating cattle it’s easy to get the impression you just need to vaccinate and your herd will be protected. Unfortunately that isn’t true. While vaccination is the foundation of every infectious disease control program, it can’t do it all alone. Producers need to do more. Producers should try to prevent the introduction of diseases. One way is to keep a closed herd. This means restricting visitors too. If you buy, buy from a herd where you know the health status. There is a big risk of bringing in disease, particularly BVD, if you buy cattle and don’t know where they came from or if you buy cattle that mix with other cattle before they get to your farm.
New cattle should be quarantined when they come into your herd even if you know the health status of the herd they came from. New cattle should be vaccinated too. Even if they have been vaccinated, it is worthwhile to booster them before bringing them into your herd.
Quarantine gives purchased cattle a chance to get sick if they became infected during the sale process. The quarantine should last three to four weeks. The degree of ‘isolation’ determines how effective the quarantine will be. Ideally, quarantined animals should be in a separate building with separate watering and feeding facilities. The further you get from this ideal, the less effective the quarantine. Some diseases, like BVD and leucosis, are mainly transmitted when cattle actually touch each other. Just keeping new cattle separated from you own cattle and using separate feeders and waterers will help prevent the spread of these diseases.
When you buy replacements, the quarantine period is a good time to test for BVD carriers. Because there has been so much BVD in Ontario since 1993, it is recommended that you use the BVD blood test on all replacements. It takes several weeks to get results so plan to take the samples as soon as possible.
The test is very accurate for detecting cattle born as BVD carriers. It isn’t so accurate at detecting cattle that were just infected with BVD virus.
Isolating sick animals, especially calves, reduces the chance the BVD or scours will spread to other animals. But it doesn’t usually work to prevent the spread of pneumonia.
Increasing the immunity of the herd will help reduce the impact of infectious diseases. Plan a vaccination program so cattle get protection when they need it most. Make sure calves get colostrum within a few hours of birth because colostrum is their most important source of immunity. Reducing stress in cattle from other diseases, poor nutrition, uncomfortable housing or poor air quality also increases their resistance to disease.