E-DRUG: Diclofenac kills vultures (2)
-------------------------------------
What can replace diclofenac for veterinary
management of pain? David Sharp in the following
letter to the Lancet describes research into role
of meloxicam.
Beverley Snell
Centre for International Health
Macfarlane Burnet Institute for Medical Research and Public Health
Melbourne
Australia
bev@burnet.edu.au
Meloxicam to prevent rabies?
[Copied as fair use]
www.thelancet.com Vol 367 March 18, 2006 887
A role for meloxicam in the prevention of rabies
sounds bizarre but let us at least explore it.
Over the past 15 years or so, three species of
Asian vulture have experienced a catastrophic
decline in numbers on the Indian subcontinent.1
The oriental white-backed (Gyps bengalensis),
long-billed (G indicus), and slenderbilled (G
tenuirostris) vultures are, in conservation
language, "critically endangered". Infectious
disease seemed the most likely explanation to
begin with, and there was even concern that the
arrival of the migratory middle-eastern and
European vulture, Þlling the gap left by its
Asian peers, would see the illness spread
westward. We think we know better now and the
very probable culprit is the non-steroidal
anti-inþammatory drug diclofenac, which has been
widely used in countries such as India in
large-animal veterinary practice.2
Vultures are, of course, scavengers and drug
residues in carcasses have proved sufÞcient to
cause kidney damage and uric-acid deposition
outside joints, or visceral gout.3 Research
released at the end of January strongly suggests
that a ban on the veterinary use of diclofenac is
practicable because a replacement is available.
This is meloxicam.4 Undertaking comparative
toxicology on diclofenac and meloxicam in an
endangered species of animal is not desirable, so
Gerry Swan and colleagues proceeded one step at a
time. Only after studies in a surrogate, the
African white-backed vulture, a bird that shares
the threatened Asian species' susceptibility to
diclofenac, had suggested that meloxicam was safe
did the research progress to ten oriental
vultures. All the G bengalensis and G indicus
were alive and healthy 4 months after exposure to
meloxicam by gavage at doses of 0·5 or 2·0 mg/kg,
the latter being above the largest dose estimated
to be had from the carcass of a treated animal.
One consequence of the decline in vulture
populations, especially in India, is the arrival
of increasing numbers of feral dogs. This change
has yet to be proved to have increased the
incidence of rabies but, in a country where the
annual risk of being bitten by a dog is already
2% or so 5,6 and which has the highest rabies
rates recorded by WHO, the scenario of a rise in
human rabies ascribable indirectly to the use of
a veterinary prescription is a real one. Nor is
this viral illness the only human effect of the
use of diclofenac in animals. Vultures have very
acid stomachs and suffer no ill-effects after
devouring the dead bodies of animals that might
have died with or of bacterial infections, such
as bovine tuberculosis and anthrax. If rats, as
well as dogs, swarm over sites previously
cleansed by vultures, plague is another
possibility. Then there is the spiritual
dimension. Just as the cow is sacred to Hindus
(hence the, to western eyes, casual disposal of
carcasses), the vulture is esteemed by some
religions as a respected way of disposing of
human remains.
David Sharp
c/o The Lancet, London NW1 7BY, UK
I am a Contributing Editor at The Lancet.
1 Pain DJ, Cunningham AA, Donald PF, et al.
Causes and effects of temporospatial declines of
Gyps vultures in Asia. Conserv Biol 2003; 17:
661-71.
2 Shultz S, Baral HS, Charman S, et al.
Diclofenac poisoning is widespread in declining
vulture populations across the Indian
subcontinent. Proc R Soc Lond B 2004; 271 (suppl
6): S458-60.
3 Meteyer CU, Rideout BA, Gilbert M, Shivaprasad
HL, Oaks JL. Pathology and proposed
pathophysiology of diclofenac poisoning in
free-living and experimentally exposed oriental
white-backed vultures (Gyps bengalensis). J Wildl
Dis 2005; 41: 707-16.
4 Swan G, Naidoo V, Cuthbert R, et al. Removing
the threat of diclofenac to critically endangered
Asian vultures. PLoS Biol 2006; 4: e66.
http://www. plosbiology.org (accessed Jan 31,
2006).
5 Sudarshan MK, Mahendra BJ, Narayan DH. A
community survey of dog bites, anti-rabies
treatment, rabies and dog population management
in Bangalore city. J Commun Dis 2001; 33: 245-51.
6 Agarwal N, Reddajah VP. Epidemiology of dog
bites a community-based study in India. Trop Doct
2004; 34: 76-78.