Video 29 Salmonella
Salmonella is a bacterial infection that can cause a range of symptoms and disease in cattle. Salmonella bacteria has several subspecies, the two most common in cattle are
- Salmonella Dublin
- Salmonella typhimurium
Depending on the age of animal infected there can be a wide range of symptoms seen. They can also infect humans (zoonosis) so great care should be taken with suspect cases on-farm,
Cows
With cows, we typically can see abortion with salmonella Dublin between 5-8 months of pregnancy. These cows can often retain their placentas after abortion and get sick. We can also see salmonella causing scour in cows. This scour can be bloody and quite smelly. We talk about a fibrinous type of diarrhea. This simply means that scour will be thickened with exudate (mucous) and even pieces of the gut lining being passed out with the diarrhea.
Calves
With younger animals, we can also see scours from salmonella as above. Younger calves from (1-8) weeks seem to be more at risk. The scour can often lead to high mortality and requires aggressive supportive therapy with fluids and antibiotics.
With young calves, we can also see a huge range of symptoms with salmonella septicaemias. These blood-borne septicemias/infections can present with things like
- Terminal dry gangrene
- Pneumonia like symptoms
- Cervical osteomyelitis
In the video above I talk more about these clinical conditions.
Treatments
Oral antibiotics may kill the bacteria but also may kill the good bacteria required for the return to a healthy functioning gut.
Where antibiotics are being given by your vet they will often opt for systemic antibiotics to treat blood-borne infections from salmonella. Like all disease supportive therapy is very important, things like fluids reversing the dehydration from the scour for example. Where you have septicemia also aggressive fluid therapy is very important.
The bacteria can also last a long time in the environment (months in feces) meaning things like slurry can pose a risk.
Carrier animals
Like a lot of infectious diseases when infected with salmonella animals can have various responses. They can show symptoms and become clinically sick. They also may not show symptoms and become immune. With salmonella, we also have the risk of animals becoming infected subclinically and subsequently become carriers of the bacteria.
This means that when they become stressed in the future they may begin shedding the bacteria. This makes the control of the disease difficult in a herd.
In Ireland, we also see issues in our pasture-based systems where we get issues with liver fluke. This parasite has the potential to cause shedding because the immunosuppression combined with carrier animals having salmonella in their gallbladders and subsequently shedding.
Make a diagnosis to make a difference
With any disease getting a diagnosis through testing is a good thing to do. This allows us to identify our challenges and look at controlling them. We can use blood tests or dung samples to confirm the presence of the pathogen.
We must also be mindful that salmonella can be monitored on bulk milk samples for routine screening, also any fallen animals must have a post mortem carried out to help make better decisions around disease control.
Controlling salmonella
The good news is there is an effective vaccine that we can use to control salmonella. Although this is of cure an added cost on a farm it is a great insurance policy against this disease.
We must also not forget the importance of biosecurity and keeping the disease out. Not every herd will be vaccinating so they must be mindful of the risks when buying stock in.
Secure boundaries, disinfection points for visitors and not sharing skurry are all crucial parts of a biosecurity plan.
As always, at high-risk times of the year, we must minimize stress in cows calving and our young calves.
With every infectious disease, it always about reducing the infection pressure and increasing immunity.
For Irish farms beware of the risk with high liver fluke and salmonella in cattle.
Thought for the day
Like many who have been housebound for the last number of weeks it gives you time to think, time maybe also to remember to not lose sight of what is truly important in this short life of ours
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