17 November 2021

Antimicrobial Stewardship – Frequently Asked Questions

Just like people, animals get sick too. Antibiotics are critically important medicines that help to keep both people and animals healthy.

When a bacterial infection strikes, an antibiotic is often the only appropriate treatment. Animals will continue to develop bacterial infections, just as people will, and there will always be a need to use some antibiotics in some animals, sometimes.

Antibiotics should never be routinely used in place of good animal care practices. However, it is vital that antibiotics remain available for a veterinarian to use when an animal is sick, or likely to become sick, from a bacterial infection.

The responsible use of antibiotics in both veterinary and human medicine is essential to protect both animal and human health, and ensure that animal-derived products, such as meat, milk, eggs, leather and wool, are safe for human consumption and use.

Antibiotics contribute to better animal health and welfare

Animal welfare always starts with good animal care and management practices that reduce the risk of disease and improve the animal’s quality of life. Healthy animals lead better quality and more productive lives, are less susceptible to infection and disease produce higher quantities and better-quality food and fibre, consume fewer resources, and support Australia’s multi-billion dollar agricultural and pet industries.

Antibiotics are just one of many tools that farmers use to keep their animals healthy and minimise the risk of disease. Animal husbandry practices that support good animal health and welfare include (but are not limited to):

  • Good housing, shelter and nutrition
  • Strong hygiene and biosecurity practices
  • Regular parasite and pest control
  • The use of vaccines to prevent disease (where possible)
  • Early detection and treatment of illness and disease
  • Use of pain relief for routine husbandry procedures (eg: tailing, castration)
  • Use of low stress stock handling techniques during mustering, handling and transport
  • Selective breeding for welfare-friendly traits, such as polled (hornless) cattle and calm temperaments

However, even with the highest possible standards of animal health and welfare, it is inevitable that some animals, at some point in their lifetime, may develop a bacterial infection and require antibiotic treatment to regain health. Bacteria are ubiquitous in the soil, vegetation and water – it is impossible to prevent the exposure of animals (and humans) to all bacteria that could, potentially, cause an infection.

Why do we use antibiotics for food-producing animals?

We have an ethical and moral responsibility to prevent illness when possible and treat sick animals when necessary. Animal medicines are essential to help farmers keep their animals healthy and support sustainable livestock production.

Antibiotics that are used in both animals and human health are known as ‘shared class’ or ‘medically important’ antibiotics. Medically-important antibiotics can only be used for animals in Australia to treat and control bacterial infections, and are available only on prescription from a registered veterinarian.

Antibiotics may be needed to:

  1. treat animals that have been diagnosed by a veterinarian with a bacterial infection. Especially when there is a non-responsive or recurrent infection, laboratory testing should be used to identify the pathogen and assist with the selection of the most appropriate antibiotic.*
    1. For example, some cows will develop mastitis during lactation. Mastitis is a very painful udder infection and requires rapid treatment with antibiotics for the welfare of the animal, and to ensure that the milk from that farm remains safe for human consumption.
    2. A human health equivalent would be a urinary tract infection (UTI). UTIs can be very painful and can lead to serious bladder and kidney infections. Someone with a UTI will be prescribed antibiotics by their medical practitioner to treat the infection.
* the cost of laboratory testing in veterinary medicine is borne entirely by the animal owner, unlike human pathology testing which is subsidised by the government.
  1. control the spread of disease in a group of animals. Infections can spread rapidly between animals (especially between mother and offspring, and within a flock or herd), so when a sick animal is identified, rapid treatment of all animals in close contact can prevent significant animal suffering.
    1. For example, cattle are susceptible to bovine respiratory disease (BRD) following transport. Invariably, some animals in the group will develop bacterial pneumonia within a few days of transport. The pathogen is highly infectious and will spread rapidly to other cattle unless they are appropriately treated to control the outbreak.
    2. In people, when there is a diagnosed case of meningitis, those who have been in close contact with the infected person are given antibiotics as a precaution to prevent the spread of the disease.
  1. prevent disease occurring in animals when infection is very likely. This could be at certain times of the year (for example, related to the seasonal activity of insects that carry disease) or at specific life stages when infection is most likely to occur.
    1. For example, young pigs are particularly vulnerable to dysentery at weaning, and can quickly develop septicaemia, meningitis, infectious arthritis, pericarditis and potentially die. A short preventative course of antibiotics may be appropriate to protect the most vulnerable piglets during this very specific life stage.
    2. Antibiotics are also used preventatively in humans at specific times when infection is more likely. This includes before and after major surgical procedures (especially cardiovascular, orthopaedic and dental procedures) or when a person’s immune system is suppressed (such as during chemotherapy).

Why do we treat groups of animals rather than individuals?

Animals are usually raised in groups and bacterial infections can spread extremely quickly between individuals. Treating and controlling an infectious disease in a group of animals is similar to treating and controlling an infectious disease in a group of people.

For example, a large naval carrier can be home to several thousand people at a time. Just like herds of cattle or flocks of chickens, naval crews live in close proximity, they need to be kept healthy and they need to receive treatment when they are sick.

On-board medical protocols are very similar to on-farm animal health protocols. Crew members get preventative care, such as vaccinations and good nutrition, to prevent illness occurring whenever possible. If a crew member gets sick, the entire population is carefully monitored for signs of infection and treated as needed.

However, infections can spread quickly, and often before a person feels unwell or shows obvious symptoms. A large number of crew members suddenly falling ill at the same time would have disastrous effects on its ability to function and perform its duties. Therefore, in some circumstances, the entire crew may need to be treated to quickly control the spread of the disease and prevent many more people from getting sick.

Managing the health of a group of animals is the same – when an infection does occur, the affected animal should be promptly treated. However, food-producing animals are usually raised in groups and it may not be possible to physically isolate individual animals. This means that the most appropriate treatment of a sick animal must consider the conditions of the whole herd or flock, including the animal species, age and condition, the severity of illness, number of animals, type of housing, the range of medicines registered for use in that species and for that disease, and the formulations of those medicines (for example, injections vs tablets vs feed additives).

The infection of an entire herd or flock of animals would be associated with substantial animal suffering and pain. Treating an entire herd or flock may therefore be necessary to prevent the spread of the disease and protect the welfare of those animals.

What is antibiotic resistance?

Antibiotics work by killing or inhibiting the growth of harmful bacteria that cause illness and disease.

However, bacteria are living organisms and they have the ability to adapt (or become ‘resistant’) to the effects of antibiotics – in other words, the harmful bacteria are able to continue to multiply, and do not die, when exposed to antibiotics that usually kill or damage them. This is called antibiotic resistance.

The development of antibiotic resistance is a natural process that existed long before modern antibiotics. It is a classic example of “survival of the fittest”, where evolution over generations encourages the survival of the strongest members of a population that are able to persist in adverse conditions – for example, a strain of bacteria that is able to survive when the person or animal is treated with antibiotics. The misuse and/or overuse of antibiotics may also accelerate the development of antibiotic resistance.

Antibiotic resistance and the threat to animal health

Just as in human health, antimicrobial resistance poses a major threat to animal health, welfare and production.

Infectious diseases can cause significant animal pain and suffering, including death. Infections that are resistant to antibiotics are very difficult to treat, and treatment options may become increasingly limited in the future as resistance develops. This poses grave dangers to animal welfare and threatens the sustainable production of food and fibre that is safe for human consumption and use.

It is critically important that pet owners and livestock producers use antibiotics responsibly, judiciously and only when needed. It is very likely that any new antibiotics developed in the future will be reserved for human use only and will not be able to be used in animals. Veterinary medicine cannot rely on the development of new antibiotics to provide alternative treatments to antibiotic-resistant infections.

We must therefore use what we already have extremely carefully to minimise the development of resistance and ensure that we are able to treat and control many debilitating animal diseases in the future.

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