Dr Kat Baxter-Smith, veterinary adviser for MSD Animal Health, provides answers around how vaccines can help combat pneumonia and reduce the disease’s long-term impacts.
A: The financial and welfare effects of pneumonia are significant.
The cost per calf is variable, with work from 2002 suggesting pneumonia in dairy calves costs £30-£500 per calf, or £60 million a year to the whole industry.
In terms of performance, it can add 30 days onto the age at first calving, reduce body weight and lower first lactation milk production by 500kg.
A: Mannheimia (Pasteurella) haemolytica is always the number one cause of pneumonia in calves which die (2012-18 APHA data).
If there is anything there to bring down the immune system, such as a virus, stress or a poor environment, it is there to move in (see panel, below).
Viruses such as parainfluenza virus 3 (PI3) and bovine respiratory syncytial virus (BRSV) usually cause the initial damage and then the M. haemolytica bacteria comes in.
This bacteria lives in the respiratory tract. If you tested a live animal with signs of pneumonia, it is likely it will come back as PI3, BRSV or infectious bovine rhinotracheitis (IBR).
However, by the time the animal is dead, those viruses have gone.
A: Vaccinating against a specific disease increases the animal’s immune response against that virus or bacteria.
If an animal has a primed immune system from vaccination, it has already seen these bacteria or viruses, so when it is exposed to them in the environment, the immune system is ready to react.
The speed of immune response is quicker and the clinical signs are reduced.
So if you vaccinate against pneumonia early, you will vastly reduce the risk of lung disease.
Creating a healthy, stressfree environment is essential to stop M. haemolytica bacteria from multiplying and causing long-term lung damage.
M. haemolytica is a normal bacteria which lives in the respiratory tract in low numbers. However, if the respiratory tract is compromised, for example from a dusty environment or stress, this bacteria can multiply and create toxins which go into the lungs and body, causing illness and death.
APHA reported a peak in M. haemolytica cases in March 2020. This could have been caused by a sudden fluctuation in temperature as the weather changed from cold to hot – leading to calf stress.
As spring calvers are likely to have more stock on the ground at this time, stress from high stocking rates could also have been an influencer.
To prevent issues, Dr Baxter-Smith advises vaccinating youngstock at winter housing and ensuring young calves are vaccinated as early as possible after birth. Good hygiene, plenty of colostrum and keeping calves in smaller groups is also helpful.
A: Vaccine choice will largely depend on risk, what pathogens are on-farm and when calves are being infected.
If you are experiencing a disease outbreak, a vet can do nasal swabs to identify the cause.
If you had problems a few months ago, then blood tests can be used to identify what challenge calves were exposed to.
Although traditionally farmers often vaccinated off the back of a problem, the risk of pneumonia is always there, so now many forward-thinking farmers are realising a preventative vaccine strategy to protect the animals before disease hits is a much more cost-effective way of keeping the animals healthy.
If you are seeing problems in young calves, Bovilis INtranasal RSP Live can be given up the nose from one-weekof-age.
It is effective against BRSV and PI3. The calf will then be protected from two weeks of age, with coverage lasting 12 weeks.
If you protect calves with an intranasal vaccine against the viruses, the secondary bacterial disease is less likely.
If you want longer, wider ranging protection which includes M.haemolytica, then Bovilis Bovipast RSP may be an option, especially if you are getting pneumonia from two months of age or older.
This is active against BRSV, PI3 and also M.haemolytica and can be given from two weeks of age onwards.
This is also licensed in pregnant animals, so it will reduce the infectious pressure that calves are born into.
Both Bovilis INtranasal RSP Live and Bovilis Bovipast RSP could be given for a belt and braces approach.
A: Handle and store vaccines correctly in a working fridge at 2-8degC.
Avoid administering vaccines during periods of stress which will affect the animal’s immune response, for example at castration or weaning.
Provide a healthy environment – avoid over-crowding or mixing age groups.
Keep bedding and buckets clean to reduce the rate of infection.
Ensure adequate ventilation with plenty of fresh air. If these factors are not right, the animal’s response to the vaccine will be reduced as it is trying to deal with other problems.
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