BLACKLEG - beware of the risk
Blackleg is a deadly disease of young cattle, usually between the ages of 6 months to 2 years. The disease is caused by a bacteria called Clostridium chauveoi which survives for long periods in soil. Blackleg is most common in animals when they are grazing, however there have been cases diagnosed in housed animals due to soil contaminated forage.
Blackleg is nearly always fatal and the first sign you see is sudden death which can affect multiple animals very quickly.
What causes blackleg?
Blackleg is caused by the activation of dormant Clostridium chauveoi spores sat in the muscle of the animal - these spores have been eaten by cattle and sheep but they settle out in the muscles usually in the hind quarters or heart. The spores need some damage to the muscle to be activated - but jostling at a TB test, being moved in a trailer, or simply cattle having a mad-do can cause enough damage to the muscle that conditions are ideal for the organism to reactivate. Once the spores reactivate they produce a toxin which results in huge areas of muscle death, gas production within the affected muscle and the toxin spreads round the body causing death within a few hours.
What signs do you see?
The first sign is often sudden death which can affect one individual, or multiple animals at once or over a few days. You may occasionally see swollen muscles, severe lameness and high temperatures but it is usually too late for these animals too by that stage.
How do we diagnose Blackleg?
We usually diagnose Blackleg on a post-mortem when we are called out to investigate a sudden death - when we cut into the affected muscle there are characteristic well defined lesions which are black and full of gas. Lesions are typically found in the large muscles of the hind legs, muscles over chest or pelvis as well as the diaphragm, tongue, or heart.
Diagnosis in a lab involves culture of the bacteria and fluorescent antibody testing; muscle tissue can be examined for typical lesions under the microscope.
What can we do in an outbreak?
Sometimes Blackleg affects a single animal, but some outbreaks can affect large numbers if the spores are widespread. It is very difficult to manage an outbreak situation as any management changes, movement, transport or handling can cause a spike of more deaths as animals inevitably get jostled which could activate more dormant spores.
If you can quietly move animals onto different grazing, do that. If losses continue we would consider using Penicillin antibiotics to try and get ahead of the outbreak - but the risk of further handling, and injecting into potential sites of spores needs to be carefully considered.
What can you do to prevent Blackleg?
Blackleg is totally preventable using a Clostridial vaccine "Bravoxin 10" - this is inexpensive and very effective in preventing the disease and we would advise all cattle farmers to consider vaccinating their youngstock before their first grazing season after we have recently dealt with a nasty local outbreak.
The vaccine schedule for Bravoxin is 2 doses, 4 weeks apart and cattle are fully protected 2 weeks after the second dose. This 6 week lag in the middle of an outbreak situation can result in a lot of losses, but once the immunity is there, the antibodies then control any further activation of spores.
Please make sure you tell us immediately of any cases of sudden death in youngstock out at grass when Blackleg is suspected.
MCF - the risk of contact between cattle and sheep
Malignant Catarrhal Fever (MCF) is a deadly disease of cattle caused by a sheep virus "Ovine herpesvirus-2". This virus is carried by young sheep without any ill effect, but when that virus passes on to cattle you see sporadic cases of MCF.
What does MCF look like?
- dull & depressed
- high temperature
- red and crusty nose
- watery eyes
- blindness and blue eyes
- ulcers under tongue
- sudden death
- +/- swollen lymph nodes
How does it spread?
The virus spreads from sheep to cattle through saliva and nasal secretions or aerosols when coughing or sneezing - there is no risk of cattle to cattle spread.
Lambs can be infected at 3-6months old and shed virus for a few months. Cattle can show signs of infection several months after contact with sheep - no one really knows why there is such a variable incubation period.
How do we diagnose MCF?
- history of contact with sheep
- blood sample to check for MCF virus
- rule out IBR and BVD
How do we treat MCF?
95% affected cattle will die within a few days; the ones that survive longer show a wider range of signs. There is very little effective supportive treatment so animals are usually euthanised.
How do we prevent MCF?
There is no cattle to cattle spread of MCF, so prevention is all about stopping contact between sheep and cattle in sheds, at pasture, with shared water/feed troughs and across fenced boundaries. Don't forget if you are dealing with sheep as well as cattle, the virus can survive long enough on your hands, overalls, wellies etc for you to spread it from sheep to cattle too.
HFV TBAS VISITS: free, practical TB advisory visits
Bovine TB is still one of the most costly and disheartening diseases affecting our industry in the UK. Despite the volatile politics, the ever changing TB policies and factors seemingly out of your control, there are things you can still do to help reduce your risk of a TB breakdown on an individual farm level.
Have you heard of the TBAS service?
TBAS has been running for four years, funded by the rural development program for England (RDPE). DEFRA has now extended and furthered the funding for the benefit of the whole of England and to include all holdings with susceptible species (such as sheep, goats and camelids), not just cattle.
The service is free for farmers and is an informal visit to discuss TB in relation to your particular farm with a vet who knows your farm, your TB history and the TB incidence in the local area. By the end of the meeting we come up with four simple, cost effective, practical recommendations based on risks identified during the visit. Recommendations could cover incoming cattle, biosecurity, wildlife risks, contingency planning in case of an outbreak or even be as specific as changing grazing patterns in particularly risky youngstock groups.
It is also an opportunity to ask any niggling questions with regards to TB, the testing procedure, or TB legislation for example. There is a second, half an hour follow up visit included in the package.
Remember these TBAS visits can be on the back of other veterinary jobs such as herd health planning, fertility work or it can be used as part of your annual CHeCS TB visit and health plan if your herd is accredited.
All farms are eligible for a TBAS visit, whether you have had historic TB breakdowns and want to review your risks, if you are currently down with a TB breakdown and want to get some more information, or if you have never had TB on your holding and want to keep it that way.
Get in touch if you want any more information or to book a visit: amy@haywoodfarmvets.com
PNEUMONIA SEASON - time to do some bloods?
Pneumonia can affect calves all year round, but we tend to see a seasonal increase over the winter months when it is more difficult to maintain air quality due to the weather, humidity and stocking rates.
We have secured some free Respiratory Pathogen Testing - this means we can blood sample 5 unvaccinated calves (older than 4 months) and see what bugs they've been exposed to and what bugs could be contributing to pneumonia patterns on your farm over the next few months.
Knowing the bacteria and viruses your calves have been exposed to helps us draw up a farm-specific plan for reducing pneumonia, reducing treatment rates and makes sure any vaccines being used are targeted and appropriate.
GET IN TOUCH:
Paula: 07764 747855 paula@haywoodfarmvets.com
Tom: 07837 291097 tom@haywoodfarmvets.com
Amy: 07507 656747 amy@haywoodfarmvets.com
Enquiries: mail@haywoodfarmvets.com
Website: haywoodfarmvets.com
Open hours: M-F 08:30 - 16:30
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