Coughing cows and respiratory disease
Over the last couple of weeks again I’ve seen the issue of respiratory disease in dairy herds. This is an ongoing challenge some dairy herds face. While we often put it under the heading of coughing cows. It is the more complicated disease of respiratory disease in adult cows. While there are some general trends every farm can be slightly different and requires investigation.
So what causes a cow to cough?
Firstly anything that irritates the nasal passages, trachea (windpipe) and bronchi can cause coughing. This condition in adult cows often is termed as upper respiratory disease and is often associated with viral infections like IBR RSV Pi3 to name a few.
This can often lead to deeper lung infections also where we can have secondary bacterial infections.
Then you can get coughing from deeper infections of lung parenchyma (the lungs themselves). This is a much deeper infection often caused in adult cows by bacterial pathogens and or lungworm.
What are the symptoms of respiratory disease
- High temperatures
- Nasal discharges
- Heavy breathing
- Milk drop
What level of coughing is a problem?
Of course, cows at herd level can give an odd cough. When coughing is persistent and frequent especially when being moved or at housing and milking. More importantly, if there is other evidence such as sick cows, milk drop etc.
Can the time of year or type of cough tell us anything?
Making assumptions is dangerous. I have seen herds with lungworm using vaccines where they thought it might have been a virus. Also dosing frequently where lungworm was suspected, with these cases turning out to be viral or bacterial. This is why we need to make a diagnosis to make a difference.
The type of cough and time of year can give us indications of what might be happening. Focusing on lungworm, the cough tends to often be very deep and when no viral/bacterial infections often present without major nasal discharges.
Of course, timing can give us indications as well. Lungworm is predominantly a pasture problem from June onwards. When we see cows coughing at housing or around calving I’m always more suspicious of viral infections.
The last number of herd issues with a respiratory disease I have seen have had underlying immune stressors involved. Watch the video above as I explain.
Immunity is key
Where we see herd incidences of any infectious agent like a respiratory disease. We must ask the question is something affecting immunity. One key thing to look at is herd production and nutrition. I have seen many cases of viral disease in dairy herds in May. Most, when investigated, have had underlying issues with negative energy.
This simply means that cows in peak lactation were going through a period where their inputs (diet) did not match outputs (milk).
While this can be ok for a short period at this time of year when it’s greater than 7-10 days we can see problems.
A lot of viruses may be circulating in our herds and need the door opened with things like an Immune drop or dietary stress.
At pasture, I have seen a huge range of factors that might play a role in respiratory disease and milk drop
Where do we start when investigating the problem?
When history and clinical signs are dealt with, this will often direct us down certain diagnostic routes.
Before we look at specific diagnostics every herd should review for any stressors in the past month before symptoms appeared. Production, as I said previously, is always a good starting point.
In summer months with coughing cows, we can take faecal samples to check for lungworm, bloods, nasal swabs or more recently more vets are opting to do highly valuable lung washes for a more accurate diagnosis.
At calving time we tend to look more at bloods, nasal swabs and looking at underlying nutritional stressors.
Your own vet is best placed to figure out where to start. Over the coming weeks in some dairy herds lungworm will be a strong differential with issues like coughing and respiratory disease.
Should cows not have immunity to lungworm?
Yes, traditionally this was the accepted principle. However, nowadays we are unfortunately seeing more adult dairy cows having issues with lungworm.
Two main reasons; young stock are being so well dosed their ability to create natural immunity to lungworm is impaired – the ‘belts and braces’ approach to worming for the want of a better term. Meaning when they enter the milking herd they are more susceptible. Ideally, we want younger animals to develop immunity over time to low levels of lungworm. This is why lungworm vaccination has a big role in problem herds.
We also have seen reinfection syndrome, this can be complicated. What happens with lungworm is there are two levels of immunity at the gut where the parasite enters the body and at the lungs. The immunity in the lungs is lifelong while the gut immunity wears off after a while.
With reinfection syndrome we have larvae getting to the lungs because of short gut immunity and not developing into adults which causes problems. These can be difficult to diagnose because they don’t fully develop into adults (because of life long immunity at lung level) meaning no eggs are produced to pick up on faeces testing.
These cases often need lung washes to diagnose.
With lungworm, we must also remember that conditions favorable for good grass growth are also the same conditions that many parasites like to spread and develop in.
Any problems with dosing frequently?
This can be costly and also may lead to resistance in the future. It is one way to control lungworm in adult cows but I feel an unsustainable one as we have only one licensed product for lactating dairy cows (Eprinomectin). My cut off point or time for farmers to change tactics is when they are dosing cows more than 3 times in the grazing season with eprinomectin. This is where I have considered and used vaccination where lungworm was a severe issue on farms.
What role does grazing and weather play?
Firstly mild wet summers are ideal for lungworm. The roblem is these conditions if favorable can mean lungworm levels in pasture can spike quickly. Add in a tight grazing system (4cm post grazing height) and heavy stocking densities and we certainly have big contributing factors in some farms.
It might be two problems one cough?
Yes on many occasions I’ve seen this.
At calving time or early summer, it can often be nutritional stress with viral infections for example. Another example during the grazing season is lungworm and viral infection, both contributing to the problem. Where cows start with a lungworm problem, over time secondary viral and bacterial infections can also affect cows.
Is this a new phenomenon?
It’s probably not all that new but we have seen a notable increase over the last 8-10 years. However, there is no doubt that worming strategies in youngstock, weather conditions and increased intensification have speeded up the process.
My top tips with coughing cows and respiratory disease
Look at herd immunity and production
Work with your vet to make a diagnosis
Where we have viral agents diagnosed consider vaccination to support herd immunity
With farms with lungworm, issues consider lungworm vaccination in long term control strategies.
Thought for the day
I’m still not sure whether technology is a friend or foe at times. There is no doubt it is a big part of our daily lives right now. This will only increase so I think for people and businesses we must embrace it.
Huge thanks to Nettex, Progiene and Rumenco for their support in putting #50in50 together for more information click here http://www.net-tex.com
Happy safe farming