Letters
Letters
PET TRAVEL SCHEME
The present and
future of PETS
The comment and report on 10 years of
the Pet Travel Scheme (PETS) (VR, March 6,
2010, vol 166, pp 284, 287) raise serious issues
with regard to the retention of controls on
the entry of companion animals into the UK.
While Defra, BSAVA and BVA have lobbied
extensively to retain additional controls for
rabies, ticks and tapeworms, the report implied
this battle had been lost. These efforts must
continue despite the desire of the European
Commission for a single harmonised system.
At present, rabies is not a significant
differential diagnosis in neurological disease
of UK cats and dogs, but this will not be
the case in the future if current controls
are lost. France and Germany perform
substantial numbers of rabies investigations
and prophylactic treatments every year
in both animals and humans despite their
apparent ‘rabies-free’ status. Additional costs
to all pet owners and the NHS for routine
rabies vaccination, and postexposure rabies
investigation and prophylaxis, must be
considered, not just the minor inconvenience
to pet owners wishing to travel. The success
of PETS in allowing movement of cats and
dogs without a single case of rabies should be
recognised, but it should also be noted that
a significant proportion of animals fail the
rabies serology test and are prevented from
travelling. While it might be argued that
some of these animals would be immune
to rabies, the disease has been recorded in
vaccinated dogs (De Benedictis and others
2009), so this seems an odd challenge
experiment to undertake in our risk-averse
society. Rabies serology is also a clear,
independent marker of successful vaccination
that it is difficult to falsify.
It should be noted that despite
improvements in rabies control in Europe
the disease is far from eradicated. Leaving
aside possible issues of under-reporting,
there are still recorded cases of rabies in
many eastern European states and northern
Italy (Health Protection Agency [HPA]
2010) and Defra’s comment that rabies is
largely confined to Romania and Latvia is
misleading. Owners taking their pets and
families to any area with active rabies should
be particularly aware of the risks of rabies,
and documented clear protective levels of
immunity to rabies at the time of travel to
such areas would, in our view, be desirable.
Free movement of cats and dogs between
continental European states (the EU-21)
means all must be regarded as rabies-positive
for movement purposes. Current OIE advice
on movement of animals from infected
countries to rabies-free countries is clear (OIE
2009). In summary, dogs and cats from such
countries wishing to avoid quarantine should
be identified by a permanent mark (such as
a microchip), vaccinated against rabies, and
subjected not less than three months and not
more than 24 months before shipment to an
antibody test as prescribed in the Terrestrial
Manual with a positive result equivalent to at
least 0.5 iu/ml.
It is difficult to understand why the OIE
advice on rabies control should be disregarded
by the EU. Although the risks of import of
rabies remain small, the different status and
history of the UK in terms of rabies freedom
is an important consideration and the media
response to an outbreak of rabies would be
challenging. We hope that Defra, the BVA
and BSAVA will continue to lobby strongly
for the retention of all current PETS controls.
Paul Burr, Susan Duthie, Kate Turner Haig,
Biobest Laboratories, 6 Charles Darwin House,
The Edinburgh Technopole, Milton Bridge,
Nr Penicuik, Midlothian EH26 0PY
e-mail: [email protected]
References
De Benedictis, P., Mutinelli, F., Veggiato,
C., Capua, I., Squecco, G., Coassin, R. &
Ferri, G. (2009) Rabies in a vaccinated dog in Italy.
Veterinary Record 165, 216
HPA (2010) Rabies in NE Italy since October
2008 (updated 15 February 2010). www.hpa.
org.uk/web/HPAweb&HPAwebStandard/
HPAweb_C/1224745740644. Accessed March 15, 2010
OIE (2009) Rabies. In Terrestrial Animal Health
Code. www.oie.int/eng/normes/MCODE/en_
chapitre_1.8.10.htm. Accessed March 15, 2010
doi: 10.1136/vr.c1504
NEMATODE INFECTION
Haemonchosis in large
ruminants in the UK
Nematodes of the genus Haemonchus
are haematophagous parasites of the
abomasum, which worldwide cause one of
the most important diseases of ruminants.
Although haemonchosis is mainly a clinical
problem in regions with warm or tropical
climates there is evidence that these parasites
have spread northwards in sheep in the UK
in recent years (Taylor 2009). However,
haemonchosis has only rarely been reported
in large ruminants in the UK. We wish to
draw practitioners’ attention to three recent
cases in domestic cattle.
The first case was seen in September
2008, when the carcase of a six-month-old
male Friesian calf from a Lancashire farm
was received with a history of illthrift,
malaise and diarrhoea. No worm eggs
were detected in a faecal sample but 1200
Haemonchus species worms were recovered
from the abomasum. These were confirmed
as Haemonchus contortus by ITS-2 rRNA
sequencing, which discriminates from the
closely related species Haemonchus placei,
which is commonly found in cattle in many
regions of the world (but not yet reported
in the UK). Results of other tests suggested
that there was concurrent acute bovine viral
diarrhoea virus type 1 infection.
The second case was identified in
September 2009 when the carcase of a
six-month-old male calf from a Devon farm
was received with a history of illthrift and
diarrhoea. Faecal examination revealed 1100
trichostrongyle-type epg, 50 Trichuris species
epg and 10,600 coccidial opg, 50 per cent of
which were of the pathogenic species Eimeria
bovis and Eimeria zuerni; 1800 worms identified
morphologically as H contortus were recovered
from the abomasum.
The third case was also identified in
September 2009 when the carcase of a
recently euthanased four-month-old Holstein
heifer from a Staffordshire farm was received
with a history of diarrhoea, dehydration and
recumbency. Fourteen heifers had been turned
out on to pasture previously grazed by sheep
and were all reported to be scouring. A worm
egg count revealed 7200 trichostrongyletype epg, 50 Strongyloides species epg and
18,900 coccidial opg; 4100 worms identified
morphologically as H contortus were recovered
from the abomasum, and 300 Cooperia species
were recovered from the small intestine.
There was also evidence of pneumonia
associated with Histophilus somni.
In October 2008, infection was also
identified in water buffalo (Bubalus bubalis)
when the carcase of a four-and-a-half-monthold male calf from a Carmarthenshire farm
was examined. Although no premonitory
signs were reported, body condition was
poor and postmortem examination revealed
liquid brown contents in the large intestine
and rectum. A worm egg count revealed
the presence of 450 trichostrongyle-type
epg. Fifty Haemonchus species worms (later
confirmed as H contortus by ITS-2 rRNA
sequencing) were recovered from the
abomasum together with 2000 Ostertagia
species.
Sheep and goats are reported to be
the natural hosts for H contortus, whereas
March 20, 2010 | Veterinary Record | 373
Letters
H placei is thought to be more adapted to
bovids. However, H contortus appears able
to infect a wide range of ruminant species
(including cattle and deer) and camelids
(Taylor and others 2007); parasites identified
morphologically as Haemonchus species
have been detected in alpacas from at least
eight different premises as a result of routine
surveillance by Veterinary Laboratories
Agency (VLA) regional laboratories over
the past three years. Cattle become immune
to haemonchosis more readily than sheep
and goats, but calves are fully susceptible
to the parasite (Craig 2009). Sources of
infection for the four cases reported here
were not determined, although follow-up
investigations for case 1 showed that it was
from a calf-rearing farm that kept only cattle.
As well as being highly pathogenic,
Haemonchus species are reported to possess
a high biotic potential associated with high
fecundity and long-lived adult stages, and
can often survive adverse conditions due
to great biological/ecological adaptation
including the ability of early fourth-stage
larvae to undergo arrested development
(Craig 2009, Kenyon and others 2009).
Climate change (a trend towards wetter
summers and shorter warmer winters) has
been suggested to be a possible reason for the
spread northwards of cases of haemonchosis
in sheep in the UK (Kenyon and others
2009). It is too early to tell whether the
four cases reported here represent changes
in the epidemiology of these parasites
and the emergence of a significant
haemonchosis problem in cattle and other
large domesticated ruminants in the UK.
However, they are consistent with the report
of Fox and others (2007), who unexpectedly
found Haemonchus larvae (of ‘sheep’ origin)
on the pasture grazed by dairy cows on
three of five farms in England that were
surveyed in 2002. The parasite had been
recovered only rarely from pasture samples
in a previous study of the same farms carried
out in 1978/79; sheep had not had access to
fields grazed by cows for over a year on one
farm where the parasite was most abundant.
H contortus is a species reported to have
a marked ability to develop anthelmintic
resistance (Craig 2009). There are reports of
anthelmintic resistance in cattle nematodes
in the UK but currently it is not thought to
be as significant a problem as it has become
in nematodes of sheep. Nevertheless,
measures to avoid resistance developing in
cattle nematodes, as advocated by Coles
(2003), should be adopted by cattle farmers.
In view of the recent cases reported
here we urge cattle practitioners to remain
vigilant for the clinical signs associated with
haemonchosis: anaemia (which may be
severe), hypoproteinaemia, weakness and
death. Note that similar signs may be seen
in cases of chronic fasciolosis. Diarrhoea
is not generally a feature unless animals
are also infected with other nematodes
causing parasitic gastroenteritis. If necessary,
appropriate faecal examinations should be
carried out to investigate possible causes
of illness, particularly if there has been a
poor response to anthelmintic treatment.
To assist with these investigations the VLA
is now able to offer practitioners a new
test (TC0777) that is able to differentiate
Haemonchus species eggs from those of
other trichostrongylid nematodes in faecal
samples without larval differentiation by
application of a fluorescent stain. The test
will detect Haemonchus species eggs in the
faeces of any host species (sheep, cattle,
other ruminants and camelids) and the
results will be reported as a percentage.
Jane Anscombe, Farm First Veterinary
Services, Unit 2, The Bryn Garage,
Penpergwm, Abergavenny,
Monmonthshire NP7 9AT
Libby Redman, Division of Infection and
Immunity, Faculty of Veterinary Medicine,
Institute of Comparative Medicine,
University of Glasgow, Bearsden Road,
Glasgow G61 1QH
John Gilleard, Department of Comparative
Biology and Experimental Medicine, Faculty
of Veterinary Medicine, 3330 Hospital
Drive, University of Calgary, Calgary,
Alberta, T2N 4N1, Canada
Robert Hogg, Kate Whitaker, VLA –
Preston, Barton Hall, Garstang Road,
Barton, Preston, Lancashire PR3 5HE
e-mail: [email protected]
Rachael Collins, VLA – Starcross, Staplake
Mount, Starcross, Exeter EX6 8PE
Paul Holmes, VLA – Shrewsbury, Kendal
Road, Harlescott, Shrewsbury SY1 4HD
Sian Mitchell, VLA – Carmarthen, Job’s
Well Road, Johnstown, Carmarthen,
Carmarthenshire SA31 3EZ
n ORIGINAL LETTERS on all topics relating
to the science, practice and politics of
veterinary medicine and surgery will be
considered for publication. They can be
submitted by post, fax or e-mail and must
give full address details of all authors
as well as a contact telephone number.
They should be typed, double spaced and
addressed to the Editor, Veterinary Record,
BMJ Group, BMA House, Tavistock Square,
London WC1H 9JR; fax 020 7383 6418;
e-mail: [email protected]. Letters may
be shortened for publication
“ I certainly would not have
entered into it if I didn’t
have clinical freedom you are the vet.”
Rachel Howard BVM&S MRCVS Scarborough
References
COLES, G. (2003) Strategies to minimise anthelmintic
resistance in large animal practice. In Practice 25, 494-499
CRAIG, T. M. (2009) Helminth parasites of the
ruminant gastrointestinal tract. In Current Veterinary
Therapy: Food Animal Practice. 5th edn. Eds D. E.
Anderson, D. M. Rings. Saunders Elsevier. pp 78-91
FOX, M., HUTCHINSON, M., RIDDLE, A. &
FORBES, A. (2007) Epidemiology of subclinical dairy
cow nematode infections on five farms in England
in 2002 and a comparison with results from 1978 to
1979. Veterinary Parasitology 146, 294-301
KENYON, F., SARGISON, N., SKUCE, P. & JACKSON,
F. (2009) Sheep helminth parasitic disease in south
eastern Scotland arising as a possible consequence of
climate change. Veterinary Parasitology 163, 293-297
TAYLOR, M. (2009) Changing patterns of parasitism in
sheep. In Practice 31, 474-483
TAYLOR, M., COOP, R. & WALL, R. (2007) Parasites
of sheep and goats. In Veterinary Parasitology. 3rd edn.
Blackwell Publishing. pp 158-161
doi: 10.1136/vr. c1509
A joint venture with Companion Care offers a proven
business model which allows you to achieve your goals
as a veterinary partner. As the UK’s leading provider of
small animal veterinary services we can offer superb
opportunities in brand new and existing locations
across the UK.
For information on partnership opportunities with
Companion Care and to listen to Rachel, please go
to our new website and download our partnership
brochure, or e-mail us direct at:
[email protected]
www.ccvets.co.uk
374 | Veterinary Record | March 20, 2010