Antibiotics for Animals
An Overview
Healthy animals mean healthy food. Animals, just like
humans, can suffer from disease. NOAH believes it would be a rejection of
responsibility towards the production of healthy food to deny animals access
to medicines which keep them healthy. Animals, like people, need antibiotics
too.
Definition
The term antimicrobial describes a medicine which
destroys or inhibits the growth of bacteria. Most are naturally produced by
bacteria and fungi, others are man-made but have the same effect.
“Antibiotic” is popularly used to describe this whole range of chemicals.
Strictly, it should only apply to the naturally derived chemical substances,
with the term antimicrobial describing the bigger group: however, we will
use this popular terminology here.
Introduction
The introduction of antibiotics has saved countless
lives. Without antibiotics, pet and farm animals would endure pain and
suffering and the safe production of food would be endangered. This position
paper addresses four issues facing the UK animal health industry:
- The correct use of antibiotics in the treatment of
sick animals.
- The appropriate use of antibiotics to ensure animals
do not fall sick.
- The beneficial use of antibiotics in animal
production.
- Resistance to antibiotics.
It concludes: animals need antibiotics, too.
Licensed Products
Like human medicines, by law all animal medicines require
official marketing authorisations before they can be marketed. Authorisation
is given only when data collected over many years’ research are approved by
independent UK and European scientific and technical experts. These data
include full dossiers on quality, effectiveness and safety for animals and
especially safety for users, consumers, and for the environment.
Of special importance is the evaluation and operation of
withdrawal periods - the time during which treated animals cannot be
slaughtered for food, nor can their products enter the human food chain.
Extensive testing by highly sensitive methods and enforcement of the
required withdrawal period by vets and farmers ensures safety of food from
such animals1.
Usage in animals
The continued responsible use of antibiotics has given
man and animals freedom from many diseases and safe and efficient food
production on farms. It is important to recognise that antibiotics cover a
very wide range of compounds, split into many different classes.
In animal medicine, antibiotics are used in two main
ways: to treat an individual or an outbreak of disease and to prevent
outbreaks occurring.
To Treat Disease
Like humans, when animals fall ill, they may need
medicines and courses of antibiotics are prescribed when necessary. These
antibiotics are available only with a veterinary prescription and it is the
veterinary surgeon who decides what to administer and when to use them. For
example antibiotics may be given in different ways, such as by tablet, by
injection, in drinking water or in food and their prescription will be for
as short a period as necessary to beat the disease.
Most farm animals are relatively young and, like
children, are susceptible to many infectious diseases. Without antibiotics,
if they contract a bacterial disease their condition can deteriorate
rapidly, resulting in suffering and, potentially, death. Disease can also
spread to other animals and in some cases humans.
Where livestock are grouped together, it is often
necessary to treat the whole group when only a few are showing signs of
illness. This is because others in the group may already be developing the
disease.
To Prevent Disease
Prevention is always better than cure, particularly in
flocks and herds where disease can spread rapidly.
To prevent outbreaks of infectious bacterial disease when
animals are most at risk, and animals are known to be susceptible, courses
of appropriate antibiotics may be prescribed by a veterinary surgeon.
Anticoccidial products are a vital part in the prevention
and control of coccidiosis, a parasite disease mainly affecting poultry (see
NOAH briefing document 13 - Anticoccidials).
In Production
A selected group of antibiotics, reserved for animal use
only, were used to help growing animals digest their food more efficiently,
get maximum benefit from it and allow them to develop into strong and
healthy individuals. This was achieved by destroying or inhibiting
undesirable bacteria in the gut which prevent optimum absorption of food.
These products are no longer used in the EU, as from 1 January 2006.
Resistance to Antibiotics?
Not all antibiotics work against all bacteria. It is
important to choose the right one and to follow the tried and tested correct
dosage levels and treatment recommendations.
Concerns that antibiotics may be losing their
effectiveness are not new.
Resistance to antibiotics is seen most commonly in
hospitals where antibiotic usage is high and where the ‘selection pressure’
creating and maintaining a pool of resistant bacteria is also high. Many
antibiotics have been in animal use for 50 years and resistance here is not
seen as a significant problem.
There is currently concern in some quarters that use of
antibiotics in animals may compromise the effectiveness of related medicines
in man. The animal health industry recognises these concerns and takes
seriously its own responsibility in this area. As a result, extensive
studies, set up in conjunction with the relevant regulatory authorities, are
underway to help shed more light on this subject. Industry is also heavily
involved, from a worldwide to a UK level, in the development of responsible
use guidelines. In the UK these are produced by
RUMA (the Responsible Use of
Medicines in Agriculture Alliance).
This type of work is not new: for decades, investigations
in many countries, and different species, have been conducted and no
conclusive evidence produced. There have been multiple resistant Salmonellae
in Europe for 30 or more years. In the 1980s, high incidence of Salmonella
Typhimurium DT204C was a major concern; that disappeared over time. More
recently, Salmonella Typhimurium DT104 has been the issue, but that is now
on the decline. So the situation is certainly not static as far as food
poisoning bacteria are concerned and is often unrelated to medicines used in
farming.
For example, in 1999, the UK's Advisory Committee on the
Microbiological Safety of Food (ACMSF) published its report recommending
'evolution not revolution', with proposals in line with the existing
responsible use initiatives.
And in 2003, the UK’s Veterinary Products Committee
published a report on antimicrobial resistance. It announced it stressing:
“Antimicrobials are essential drugs for the treatment and prevention of
disease. They help reduce animal suffering and contribute to the production
of healthy food.”
In 2004, an international group of leading independent
scientists, headed by Professor Ian Phillips, published a critical review of
the all the research and information relating to the question “Does the use
of antibiotics in food animals pose a risk to human health?” In all, some
276 references were cited in the review. Their main conclusions were: “All
the facts at our disposal persuade us that whereas resistance is undoubtedly
selected in man and animals by the use of antibiotics, in organisms that are
part of the normal flora as well as in pathogens, including zoonotic
pathogens, and whereas some resistant organisms can be shown to reach man
via the food chain, little additional harm results from resistance, even
when infection supervenes. Only in the case of salmonellae and
campylobacters do risk analyses, albeit still hampered by a lack of data,
suggest that resistance possibly acquired in animals may add, albeit very
little, to the burden of human disease.” (Ref: I Phillips et al (2004),
Journal of Antimicrobial Chemotherapy 53, 28–520)
These conclusions were endorsed by Prof Phillips' 2007
paper "Withdrawal of growth-promoting antibiotics in Europe and its
effect on relation to human health". (Ref: I Phillips (2007)
International Journal of Antimicrobial Agents 30, (2007) 101-107)
(For more information see NOAH briefing document No 11
Antibiotic Resistance).
Conclusions
-
Antibiotics are essential for animal
health and welfare and offer significant environmental benefits.
-
All
antibiotics used in animals are thoroughly tested and independently assessed
prior to their approval for use.
-
Farmers and their veterinary surgeons
have responsibility for observing post-treatment withholding periods to
avoid residues in the final food.
-
All groups involved in food production
have agreed common “Responsible use policies” for all medicines, including
antibiotics. An example of this is the guidelines produced by RUMA on
responsible use of antimicrobials in the major farm species.
-
The concerns
about potential impact on human health continue to be addressed by industry
and independent bodies.
-
There is a remarkable lack of documented evidence
that use of antibiotics in livestock has been proved to cause treatment
failure in people.
-
Antibiotics must remain available for animal usage.
Updated October 2007
1 NOAH publishes a comprehensive listing of manufacturers'
recommended and approved withdrawal periods in the
Compendium of Data Sheets
for Animal Medicines.
|
