Part one, published last week, examined the role of antibiotics and antibiotic resistance. Part II looks at the use of antibiotics.

THE European Medicines Agency (EMA) is the EU organisation tasked with medicines availability and usage across the EU member states. They published a report in October 2014 which revealed EU antibiotic use in animals reduced by 15% between 2010 and 2012.

These welcome figures prove that both veterinary surgeons and owners are taking the threat of antibiotic resistance seriously and actively seeking alternatives to over-reliance on antibiotics.

Antibiotics are only useful in the treatment of active bacterial infections.

They are no use in dealing with disease outbreaks caused by viruses. Nor are they of any use as a preventative treatment as the bacterial population must have already invaded the animal’s tissues and be multiplying for antibiotics to be effective.

So by the time the animal will benefit from being placed on antibiotics, it is already sick and the owner must now invest time and effort in nursing it back to health. Veterinary costs can quickly add up and even where the patient makes a speedy and uncomplicated recovery; training programmes are interrupted and production or competition targets may be delayed.

Good husbandry can reduce both veterinary costs and antibiotic usage.

Horses that are in good body condition due to a nutritious diet with plenty of high quality forage have a healthy and diverse population of the “good” bacteria in their gut; helping them to avoid colonisation by potentially harmful bugs.

Regular foot care, dental checks, pasture management, adequate shelter, a clean environment and parasite control all contribute to the overall health of the horse. Well cared for horses are less prone to disease and have better healing ability if they do get sick or injured.

Of course, no matter how careful you are, illness and injury will occur from time to time. When antibiotics are necessary, your veterinary surgeon will prescribe them. Ideally the choice of drug should be evidence-based to increase the chances of a successful outcome.

Veterinary surgeons will select the most suitable drug to use based on the signs of disease present, their knowledge of the bacteria most likely to be involved and their experience of similar cases.

Diagnostic tests can greatly facilitate this decision-making process by giving the veterinary surgeon more accurate information to base their choice on.

BLOOD TESTS

Blood tests are often used to measure the number and type of white blood cells involved in the immune response.

Infection and inflammation in general will cause the total number of white blood cells in the blood to rise, as the animal’s immune system tries to overwhelm the invaders. If the invaders are bacteria, then the two types of white blood cell that will be commonly increased are neutrophils and monocytes.

If the animal has a viral infection, lymphocytes will typically be elevated.

The results of this type of blood test are rapidly available so you can normally find out within hours (1) if the horse has an infection and (2) if antibiotics are likely to be of any use or not.

The more accurate the initial diagnosis, the better the chances of a rapid and successful outcome. This approach also saves money overall, as it reduces the likelihood that antibiotics will be employed in cases of viral infection, where they are of no use. It also decreases the risk of antibiotic resistance.

If blood tests indicate a bacterial infection, the veterinary surgeon can take a swab or sample of fluid/tissue from the infection site. Various laboratory techniques can identify the exact bacteria involved and check what specific antibiotics will be effective against it.

Again this can save money and improve patient outcomes by allowing targeted treatment.

The development of new techniques, such as PCR testing, has allowed results to be available much more rapidly for many common conditions e.g. strangles.

These test results also benefit the owner as it means that disease control measures, such as isolation of infectious animals, can be put in place immediately. Once you know exactly what infectious agent is present, you can also devise more effective control measures, e.g. selection of an effective disinfectant.

When using antibiotics, a good rule of thumb is “as little as possible, as much as necessary”. They should not be used unless the patient actually requires them but once necessary, they should be administered at an effective dose for long enough to ensure the infection is cleared.

Always give the antibiotic exactly as recommended by your veterinary surgeon and ensure you administer the complete course.

In many cases the animal will be well improved before the course of treatment is due to end but it is important that you continue to ensure there are no bacterial “stragglers” left behind.

Another important aspect of antibiotic treatment is the length of time they take to kick in: typically 48-72 hours before an obvious improvement is seen in the patient. It is important not to be tempted to chop and change antibiotics during this time. Supportive nursing care is very important: keeping the animal as clean, warm, dry and comfortable as possible will help the medication do its job as quickly as possible.

Karen Dunne MVB MA, CertEm (Stud Med) is a vet and veterinary nursing programme director at Dundalk Institute of Technology. She’s a member of Veterinary Ireland Equine Group.

E-mail: hq@vetireland.ie

Telephone: 01-4577976