NADIS Veterinary Report and Forecast
May 2009
CATTLE
ADULT CATTLE
Overall the number of reports in April was relatively low, with many
practices reporting much less work than usual. However, as always there were
large differences between practices with some vets reporting that April was far
busier than expected!
Metabolic disease
The number of displaced abomasum reports showed their
expected fall in April, but despite the fall in overall work there were still more
reports of DAs than in 2007 and 2008. So for the first time since 2004, there
were more reports in January to April this year than in the previous year
(Figure 1)
Figure 1: Change in number of reports of DA in January to April
– showing the rise in 2009 after 4 consecutive years of falls.
Acetonaemia cases dropped precipitously in April, falling to
well below the long term average, continuing, for a third year there was a
decline in the number of reports of acetonaemia received during January to
April (Figure 2). Comparing these figures to DA reports clearly shows that the rise
in DA cases has not been accompanied by a rise in acetonaemia cases; although
these diseases may share several risk factors, they are clearly not strongly
linked with modern dairy management increasing the one but not apparently the
other (Figure 2).
Figure 2: Number of reports of acetonaemia during January to April,
and this number as a percentage of DA cases during the same period.
Fewer hypomagnesaemia cases were reported in April than in
any previous year. Magnesium management appears to have improved dramatically
since NADIS started in 1997 with the number of cases reported in the last three
years being equivalent to one years worth of cases in the late 1990s. It would
be interesting to get your thoughts as to why this is the case – some may be
due to farmer treatment of cases but how important do you think improved
nutrition has been and if it has what do you think has prompted that change?
Fertility
The number of reports of anoestrus echoed those of 2008 very
closely, falling in April from a very low level in March, with the number of
reports being only 10% higher than April 2008, which was the lowest for that
month in any year except 2001. In
contrast, reports of ovarian cysts were much lower than last year, tracking the
long-term average rather than being 50% above. Again these NADIS data show that there must be
significant differences in the risk factor for these two diseases even though
both are often linked to high milk production and insufficient feed.
Figure
4: Monthly reports of ovarian cysts
Uterine torsion reports increased steadily between 2000 and
2006, except for an upwards blip in 2004 but then fell in 2007. However in 2008,
reports increased to levels near those seen in the peak year of 2004, so the
upward trend seems to have begun again
Comparing the number of reports of uterine torsion to those
of dystocia gives us further information. In 1997 just under 6% of cases were of uterine torsion, last year this had doubled to almost 12%
(Figure 5). So far this year the equivalent figure is only 8% but this low
figure reflects the increased seasonality of uterine torsion compared to
dystocia. This is clearly shown in the time series presented in Figure 6 which
shows an increase from around 5% in the early months of the year to around 15%
in the peak summer months.
Figure 5: Change proportion of dystocia reports that are due
to uterine torsion (The low figure for 2009 reflects the increased seasonality
of uterine torsion compared to dystocia)
Figure 6: Time series graph of proportion of dystocia reports which
were due to uterine torsion, since 2005. The peak month in 2008 was November
which had relatively few dystocia cases
It is only with long term
data, such as that collected by NADIS veterinarians, that we can identify such
changes and highlight them. Ideas as to why dystocia in the summer is more
likely to be associated with uterine torsion than in the winter would be
gratefully received.
Vet 46 (North Yorks) reported
that he is finding that post calving metritis is becoming more and more of a
problem in large, high yielding herds with a few ongoing problem cases on each
farm. One of his clients has not changed size (130 cows) but average production
has gone from 8,500 to 9000 litres at the same time as a large increase in
dirty cows. Certainly, increased negative energy balance has been linked to
increased persistence of uterine infection so it would be interesting to see if
this pattern is also occurring elsewhere?
Vet 74 (Mid
Lameness
The low figures for lameness treatment in the first four
months of 2009 confirm the long-term trend of reduced veterinary involvement in
lameness. This is by no means a necessarily bad thing, we should be focussing
on prevention rather than remedial treatment, but we still lack well-designed focussed
control plans – equivalent to the mastitis 5-point-plan – which are readily
available for use on farm. So far research has shown that lameness intervention
is generally much less effective than mastitis control. Hopefully,
Figure 7: Number of reports of lameness in January to April from
1997 to 2008.
Other diseases
Vet 81 (Northumberland) reported
what appears to be an unusual multifactorial problem on a client’s farm. The
cattle have been in poor condition for several months and have been diagnosed
with selenium deficiency. However there has been a relatively high level of
unexplained deaths and down cows – with the only abnormality discovered being
slightly raised urea which has been linked to insufficient ruminal protein
supply. However he also reports that the affected group of cattle has large
numbers of ticks, so further investigation into the possibility of louping ill
being involved is currently ongoing. Other reports of louping ill in cattle
would be welcomed.
Another veterinarian reported a dairy heifer had a marked
reaction to dinoprost (PGF2α analogue), with marked cellulitis
down the leg and also cranially. The affected heifer was off feed, depressed
and pyrexic. This was correctly reported as an adverse drug reaction; it is a
well-recognised side effect of PG injections, but often appears to occur in
‘outbreaks’ with large numbers of cattle affected at the same time. Another
drug reaction was also reported in April. A beef cow went down a couple of days
after being vaccinated for Rotavec. The reporting vet stated that he sees a
couple of cases like this each year and that he has previously diagnosed hypophosphataemia
in such cases.
Clostridial diseases are ever present, with reports of
significant problems at least every other month. This month, Vet 86 (Staffordshire) reported an unusual appearance of tetanus. Last year the farm had had some calves
with tetanus, 6 calves were affected with two dying. In April, one of his colleagues
performed a laparotomy on a cow that he suspected could have an LDA, although
he was not convinced. During surgery they realised that the problem was
actually tetanus. Despite supportive treatment the affected cow died three days
later. The vet does not understand where this tetanus has come from. The
affected cow had calved 10 days ago with a perfectly normal calf. He recorded
that the general hygiene on the farm was pretty grim, but the cattle were all
on concrete floors with bedding. This case highlights the fact that not all
tetanus cases have the classic ‘sawhorse stance’
CALVES
Like lameness, the involvement of NADIS veterinarians in
treating calf diseases is on a long slow decline. Again like lameness, this is
not necessarily a bad thing as the best use of the vet in relation to calf
disease is in prevention. In contrast to lameness, our ability to prevent calf
disease has probably improved with better understanding of how to improve the
environment, better understanding and monitoring of colostral management, and
more use of better vaccines.
However, no matter how good our potential preventative
regimes are, they need applying to work. Vet 46 (
Even with good preventative regimes in place things do not
always go to plan. Vet 81 (Northumberland) illustrated this nicely in April.
Firstly, he reported the apparent failure of a vaccination programme - a rotavirus
outbreak in a vaccinated farm. Investigations are ongoing. Secondly, he was
confronted with the Achilles heel of any preventative programme – unexpected
disease. Post-mortem examination of a month old calf scouring with severe
bloody enteritis identified Giardia as the cause. Giardia is a recognised cause
of calf scour but is not common enough to have its own line in the VLA/SAC
diagnosis. The vet thought that the disease had probably been present in 2008
as a calf had developed similar signs before dying that year but had not been
necropsied. A second calf in the group which had a non bloody scour was treated
with fenbendazole and responded. All other calves are going to be treated as a
precaution and the water will be tested as the shed housing the calves receives
water from a spring (as do nearby houses).
The number of joint ill reports in April was half that of
last year, nevertheless because of relatively high figures earlier in the year
there were still more cases in the first four months of 2008 than in the same
period last year – the second year in a row this figure has risen. Overall, though the figures are still well below the numbers
from the late 1990s. It would be interesting to know the drivers for
calling a vet to treat joint-ill – is it numbers of calves affected, severity of disease or value of the calf?
Figure 8: Reports of joint ill in January to April and for the whole
year compared to reports in 1997
Lambing problems
The number of reports of dystocia peak in March and April. Like many
sheep problems, the numbers reflect market conditions as well as changes in
management. So far this year dystocia cases have been below the long term
average, but around the same number as last year
Figure 9: Reports of dystocia in sheep in January to April compared to the 2001
figures (the lowest ever reported by NADIS).
Abortions
The abortion season has passed,
again NADIS reports show that there have been significant problems with
enzootic abortion and toxoplasmosis, both diseases which can be controlled with
vaccination. We would be interested to hear you’re your views on why
vaccination is not used in many flocks. Is it simply a matter of cost? Campylobacter abortion was also common, on several
farms it appeared in combination with toxoplasmosis and EAE.
Other diseases
Lameness in sheep is top of the
list of welfare problem. Footrot is the main problem but other diseases can
also have a significant impact., with contagious ovine
digital dermatitis being the newest of these. Vet 74 (Powys) reported that one
of his clients had a lot of CODD in housed ewes, which had been treated with topical
tetracycline sprays without benefit. He visited the farm, prescribed systemic
tilmicosin and topical lincomycin / spectinomycin. Within 5 days the sheep
looked totally different; for a disease which looks so terrible the response of
CODD to effective treatment is absolutely amazing!
Sheep
Census Report
NADIS is now collecting focussed surveillance data from 325
sheep farms across the
Pasteurella
Pasteurellosis is undoubtedly one of the most important
infectious diseases of sheep, affecting all classes of stock and producing a
wide range of symptoms, including sudden death, abortion and pneumonia.
Pasteurellosis tends to be a sporadic disease and thus is best controlled by
vaccination. The NADIS figures suggest that around 50% of flocks have reported
pasteurellosis in the previous year, with 64% using vaccination in at least
some age groups. All flock types have a significant reported prevalence of
pasteurellosis. The lowest prevalence is in the lowland flocks, which may be
due to less environmental stress in those conditions but may also be due to the
higher prevalence of vaccination in this group. The highest prevalence is in
upland flocks despite the use of vaccine in this group being much more common
than in hill sheep.
Figure
17: Comparison between flock types in prevalence of pasteurellosis and
use of vaccine
Clostridia
Clostridial disease, like pasteurellosis, is usually
sporadic in nature and is also effectively controlled by vaccination. Unlike
pasteurellosis, treatment is almost always unfeasible, so antibiotic treatment
is not an alternative to vaccination. In virtually every case of clostridial
disease reported by NADIS veterinarians either animals have not been vaccinated or the vaccine was given too close to lambing to
stimulate sufficient colostral immunity.
Overall, almost 90% of flocks reported vaccinating, with 83%
of farms using a complete ewe programme, i.e. administering a booster dose
about 4 weeks prior to lambing to maximise colostral protection. Undoubtedly it
is this reliance on colostral protection, which is particularly important for
diseases such as lamb dysentery and tetanus, which means that far fewer lambs
receive a full clostridial vaccination programme (45%)
NADIS
BPEX Commentary – May 2009
A full year
has now passed since the BPEX funded research programme into PMWS started, in
which a subsidy to vaccinate against this disease was provided.
Date from
NADIS surveillance shows the rapid increase in farms using vaccine in the
spring of last year with the percentage of farms vaccinating later levelling
off to close to 70% (see graph 1). This
is likely to be reflected across the whole of the English pig herd.
NADIS monitoring, however, includes recording
whether the disease is actually present on the farm and graph 2 barely reveals
any reduction of the disease over the last year. This is not to say that the effects of
disease have not decreased – anecdotal reports widely include reduced
mortality, reduced sick pigs and more even growth – but does highlight, as
expected, that vaccination, at least in the early stages, does not lead to a
complete disappearance of disease from farms. It will be interesting to see over the next year whether, as a result of
prolonged vaccination, the number of farms still seeing clinical disease
declines.
In terms of
the application of vaccination there would appear to be very little regional
variation with current uptake representing in the region of 70% of affected
farms across the country (graph 3) although this is slightly lower in
In terms of
vaccine uptake by farm type (graph 4) it is perhaps slightly surprising to see
that the breeder/weaner farms have a greater uptake than breeder/feeders (89
& 74% respectively). This may be due
to pressure from purchasers of 30kg weaners demanding vaccine to be used either
in the sows or at weaning. Conversely,
the proportion of breeding only units which vaccinate is much lower (57%). This may well be because purchasers of 7kg
weaners prefer to vaccinate themselves on arrival rather than requiring sow
vaccination or for the breeder to inject piglets before supply.
There is
little variance in presence of PMWS across management systems (graph 5) especially
with respect to batch versus continuous flow and indoor versus outdoor derived
pigs. However, the percentage of
straw-based farms reporting the presence of PMWS continues to exceed those
slatted farms with the disease. This may
continue to suggest that hygiene and dung recycling remain major components in
the development of this condition.
Vaccination
has been something of a relief to the industry but many clinicians believe that
wholesale use of vaccine over a two year period will be needed before its
benefits can be fully evaluated. NADIS
surveillance will continue to monitor these benefits.
A report
from BPEX of the results of the research programme is expected within the next
month.
Copyright
© NADIS 2009 www.nadis.org.uk