The Use of Fluoroquinolones in Animal
Health
Introduction
Animals, like humans, suffer from bacterial infections
which may need to be treated with antimicrobial drugs. These must always be
prescribed by a veterinary surgeon who has the choice of several groups of
antimicrobials, including the fluoroquinolones.
What are fluoroquinolones?
Fluoroquinolones are a modern group of synthetic
therapeutic antimicrobials, active against a range of bacteria.
With most therapeutic antimicrobials used to treat
bacterial infection in animals there are related antimicrobials used in
human medicine from the same family. This is also true for the
fluoroquinolones, which is inevitable because frequently similar bacteria
cause disease in humans and animals and so have to be treated with similar
antimicrobials.
All therapeutic antimicrobials are categorised as
Prescription Only Medicines - Veterinary (POM-V) and so are available only
on prescription from a veterinary surgeon. Labelling directs veterinary
surgeons toward prudent use.
Marketing Authorisation
Therapeutic antimicrobials must pass strict examination
by the Veterinary Medicines Directorate and fulfil criteria of safety,
quality and efficacy before being allowed a Marketing Authorisation for use
in animal health. 'Safety' includes safety to the treated animal, the user,
the environment and, for farm animals, the consumer.
In products used for farm livestock, a withdrawal period
is calculated i.e. the time that must follow after the last treatment before
the animal, or its produce, can be used for human consumption.
(For more details on what is needed to get a marketing
authorisation, see NOAH briefing document 19
‘Controls on animal medicines’)
How are fluoroquinolones given?
Around half a dozen fluoroquinolones have marketing
authorisations in the UK, for use in one or more of the following species;
cattle, pigs, chickens, turkeys, dogs, cats and other pet animals.
When dogs and cats need antimicrobials, the veterinary
surgeon treats an individual animal. A combination of fluoroquinolone
injections and tablets may be used. Other pet animals may have medicines
administered orally in water or milk. Cattle and pigs are treated on an
individual basis with oral or injectable products.
When chickens or turkeys become ill, it is necessary to
treat all in-contact birds i.e. all the birds in the one shed. Some birds
will be showing clinical signs whereas some, although they may appear
clinically normal, may be incubating the disease. Fluoroquinolones are given
in the drinking water for a short period of time under the direction of the
prescribing veterinary surgeon.
Why is there concern about their
use in animals?
For some time now, scientists have been debating whether
the use of antimicrobials in veterinary medicine might have an adverse
impact on public health. At the core of the debate is the fact that
treatment of animals with antimicrobials can lead to the development of
bacterial resistance, as also can occur following human therapy. It is
postulated that, if these bacteria are passed from animals to humans through
the food chain, then reduction in the clinical efficacy of an antimicrobial
could be possible. However, a World Health Organisation meeting in 1998,
while stressing the need for care in the use of fluoroquinolones, did not
find any clear evidence of harm to man from the use of these products in
animals. Subsequent meetings have resulted in various recommendations to
further contain possible development of resistance.
Nevertheless, in the United States, the Food and Drug
Administration (FDA) have withdrawn the use of fluoroquinolones in poultry.
The scientific basis for this action has been challenged by various
institutions representing the poultry veterinarians and the manufacturer.
They are convinced, as are many scientists and officials, that the
responsible use of fluoroquinolones for the therapy of life-threatening
poultry diseases does not result in a danger to public health. In Europe
(2001) the European Medicines Evaluation Agency gave the opinion that
reducing therapeutic medicines available to the veterinary surgeon can
result in animal health problems which ultimately can also be considered a
threat to human health.
Industry guidance for
fluoroquinolone use
Fluoroquinolone antimicrobials are recognised as making
an important contribution to the treatment of disease in both human and
animal patients. The UK animal medicine industry re-emphasises the following
principles which guide their responsible marketing and give advice for use
of this important group of antimicrobials.
1. Farm hygiene and management programmes such as
vaccination, appropriate animal husbandry and care should be used, as relevant,
to reduce disease and the need for therapeutic intervention.
2. Fluoroquinolones should only be used where the
prescribing veterinary surgeon believes that fluoroquinolones are the most
appropriate antimicrobial for an indication specified in the UK Marketing
Authorisation and in accordance with current UK and EU legislation:
(i) Fluoroquinolones can only be given under
prescription by a veterinary surgeon: they are classified POM-V
(Prescription Only Medicine - Veterinary).
(ii) They are for therapeutic use only, on the basis
of professional experience of the individual case or farm and, where
clinical circumstances allow, following sensitivity testing to determine
the most suitable treatment. In anticipation of emergency disease
outbreaks where there is no time to conduct sensitivity testing of
target pathogens (eg E Coli), regular susceptibility monitoring
is carried out.
3. Advertising must comply with the requirements of the
NOAH Code of Practice for the Promotion of Animal
Medicines and current UK legislation.
Monitoring sensitivity
The animal medicine industry in the UK and elsewhere is collaborating with
national authorities on the development and interpretation of
monitoring programmes designed to identify meaningful changes in the
sensitivity of human and animal pathogens to fluoroquinolones (and other
compounds). We will continue to work with the veterinary
and medical professions to develop the data necessary to enable
scientifically valid decisions to be taken on the appropriate selection and
use of antimicrobials in humans and animals.
Reviewed October 2007
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