30 Nov 2015
Peter Edmondson
Job Title
Figure 1. Mycoplasma accounts for one in six cases of bovine respiratory disease in Ireland.
This is the second article from the Cattle Association of Veterinary Ireland (CAVI) conference, held in Mullingar in October. Part one featured in VT45.47.
William Byrne from Ireland’s Department of Agriculture discussed Mycoplasma bovis as an emerging problem in Irish dairy cows since 2013.
M bovis has no cell wall, so penicillin or cephalosporins are not effective in treatment.
Up to 2012, the key signs were respiratory symptoms. Mycoplasma arthritis can be a sequel to respiratory infections, or as a primary presentation, and responds poorly to treatment. The severity of arthritis can vary. The joints are usually intact and it’s not a purulent infection; there is a serofibrinous discharge.
Mycoplasma mastitis was very uncommon, but has been seen recently. Cases are non-responsive and can spread from quarter to quarter via the bloodstream. Often, the samples have sediment and it’s easy to confirm using PCR testing. Samples are also cultured. This infection can spread from cow to cow via the liners, hands and common cloths. Many of these cows are culled.
You need to identify the infected cows and milk them last to avoid spread. Many will eventually self-cure, but you need to confirm this with a few bacteriology tests to be sure. This can take several months.
In 2013 and 2014, there were problems with acute onset lameness with joint swelling. Several cows were affected at the same time, but no respiratory signs were seen. Some herds had mastitis, but rarely in a lame cow. Animals do not like extending the inflamed joints so the limb is often held out straight in front or behind.
In one 100-cow herd, 12 cows became lame in a two-week period. Mostly there was one swollen joint – fetlock, carpus and hock. Response to treatment was poor and you need to warn farmers more cases are likely.
Twenty-two cows in a 200-cow herd were affected with arthritis in seven weeks. An initial acute phase died out, M bovis was isolated from all joints, anti-inflammatories and antibiotics were administered and mastitis was not identified. The farmer ended up culling all 22 cows.
Two-thirds of cases where Mycoplasma pneumonia is found are also associated with another infectious agent. In Ireland, Mycoplasma accounts for one in six cases of bovine respiratory disease (Figure 1). It is common to have animals infected with different infectious agents at the same time in the same herd. Morbidity can range from 1% to 100%, with an average of about 40%. Mortality can also vary. There are limitations to vaccination and treatment with any respiratory disease, so the focus should be, for example, on prevention through a good environment, reducing stocking densities and avoiding mixing different age groups.
Roger Ayling, team leader on Mycoplasma from APHA in Weybridge, told delegates M bovis is host-specific and not zoonotic. M bovis can cause reproductive/eye infections and meningitis, as well as the well-documented conditions. Other Mycoplasma species can also cause these conditions.
Mycoplasma mycoides causes contagious bovine pleuropneumonia and was eradicated from the UK in 1898, but has a habit of reappearing. It was isolated in Italy in 1990 and is commonly found in Africa. About 60% of all Mycoplasma diagnoses are due to M bovis alone, but 40% have different Mycoplasma strains involved. Some strains produce biofilms and can occur intermittently. These factors have implications for the host defence mechanisms, response to antimicrobial treatment and its ability to survive in the environment and resist disinfectants. Biofilms can account for animals that relapse after an initial successful treatment; there is a lot more work to be done in this area.
John Mee from Moorepark discussed managing the cow at calving.
The vet’s role in calving has changed as most cows are calved by farmers. Dystocia and caesareans in dairy cows have significantly reduced through improved breeding. Calving alarms are more common; a decade ago they were research projects. Many larger herds have highly trained staff to calve cows and a written standard operating procedure.
The average dystocia rate is less than 10%. Some well-managed herds have virtually no problems, while some have severe problems.
You need decent facilities for safe calving – for the cow, calf and operator. It’s always a good idea to ensure plenty of space for calving cows (Figure 2). Individual boxes, if used, should be big enough for ease of managing the cow.
Calving pens, ideally less than 10 cows per pen, allow better use of labour. Cows like to calve in exclusion, but still be in touch with other cows. Communal calving pens can allow for this, especially if some large bales are put in the shed to give a “quiet area” for birth. Communal pens do increase the risk of spread of Johne’s disease.
Move cows well in advance of calving or immediately beforehand. If they are brought in early and don’t calve for a while, they are blocking the pen and there will be a greater risk of metabolic problems. Ideally, move two or more days before calving to allow adaptation time.
Irish calving intervention rates are 40% for heifers and 28% for cows. The questions for the farmer are whether to intervene and when – difficult decisions. Any exploratory examination should be gentle. Leave the animal if everything is okay; don’t upset the birth process.
Lance Corporal Jones said in Dad’s Army: “Don’t panic Captain Mainwaring.” This is the best way forward. Of course, many farmers will have no idea when cows started to calve and decision-making at 3am and 3pm will be totally different. If you go in too early you can end up with more problems and a more difficult calving as the animals have not fully opened up and relaxed. Calf survival will also be reduced.
In Ireland, most farmers intervene an hour after the waterbag appears. Too early is when the muzzle has not appeared; too late is when the calf is cold or the tongue swollen.
Wait until the muzzle appears before starting to calve the cow. Farmers are often very busy and just go ahead and pull rather than coming back to check the cow later. This often causes difficult calvings, complications and damage to the cows.
Calving jacks are useful, provided they are used correctly, but remember, most farmers are not trained in their use; it is an excellent veterinary training opportunity.
Around 40% of embryos will be lost by 30 days. The definition of abortion is fetal loss after 42 days. At this time it will be 3cm in size so will easily be missed. In reality, farmers may well miss abortions from pregnancy diagnosis to 120 days pregnant when the fetus will be about 1kg.
Conference chairman Conor Geraghty discussed the new Irish rural development plan.
Irish vets have been involved in discussion groups which farmers were paid to attend.
Sustainable animal health is a proposal using vet-led technology transfer on-farm and will start in 2015/2016. There is an EU budget of more than €100 million (£70.6 million) for the five-year programme for all species.
Farmers will receive €750 (£530) per year for attending five meetings and there will be a variety of topics. This encourages farmers to attend as they are compensated for their time away from the farm.
Farmers must complete a farm improvement plan, which includes a breeding plan. Parasite control and fertility areas are mandatory and there is an on-farm risk assessment carried out by the farm vet. This takes about two hours to complete and is very comprehensive. This is an industry-led coordinated programme.
There is also funding for targeted disease control, which is being run by Animal Health Ireland, another industry-led initiative supported by all vets and the farming and milk processing organisations.
This predominantly focuses on cell counts, Johne’s disease, infectious bovine rhinotracheitis and bovine viral diarrhoea, and has proven highly successful in its progress since inception. This type of approach works because all the industry parties work together.
This programme will generate income for vet practices, but in reality, it drives progress and increases skill sets, building more sustainable farming enterprises and helping to ensure vet practices grow and develop.
