Best-practice medicine use – the five Rs

Find out why the five Rs are critical to responsible medicine use on farm.

The five Rs of using medicines are:

1. Right animal.
2. Right medicine.
3. Right route.
4. Right dose.
5. Right time.

Only animals with bacterial infections will benefit from antibiotic treatment. To this, we can also add two further Rs:

• Record all medicine use
• Report any treatment failures to your vet or the VMD

Medicines must only be used on prescription and under instruction of a veterinary surgeon. The animal(s) to be treated must be under their care and should follow a veterinary visit or consultation. The welfare and likely recovery of the animal(s) to be treated must be considered before starting treatment, and regularly reassessed during its course.

Medicines prescribed for one condition should never be used for a different condition without authorisation from your vet.

Prompt treatment reduces animal suffering, improves the chances of recovery and reduces the risk of disease spreading to other animals in the group.

Sick animals should be isolated from healthy animals to reduce disease spread.

Getting the dosage right is very important, regardless of the medicine being used.

Every medicine licensed in the UK has undergone rigorous testing to calculate the optimum dosage and route of administration for each species for which it is licensed. This information is provided on the data sheet, box or bottle supplied with the medicine.

It is vital to give the correct dosage when treating an animal. This is to avoid the drug not working and resistance developing because of overdosing or underdosing. Animal welfare can also be compromised by overdosing, as many medicines are toxic if too much is given. The stated milk and meat withdrawal times only apply if the medicine has been given at the correct dosage by the right route of administration.

There may be times when the vet will prescribe medicines to be used at a dosage rate that differs from that stated on the data sheet or for a species that is not listed. In these cases, the vet will advise on the withdrawal periods that apply.

Dosages are usually given in millilitres per kilogram (ml/kg). Always weigh animals before treatment – judging weight by eye nearly always underestimates an animal’s weight.

When a group of animals are to be treated:

• Weigh the heaviest and the lightest animal in the group
• If there is a wide variation between the heaviest and lightest animal, split the group into subgroups of more even weight
• Within each subgroup, calculate the dosage according to the heaviest animal in the group

The data sheet will give additional important information, such as the maximum volume that can be injected in one site and any special precautions.

Remember to check the accuracy of the weigh scales before starting.

Example dose rate:

• Dose weight 2 ml/20 kg
• Animal weight 65 kg
• 65 ÷ 20 3.25
• 25 x 2 6.5 ml

When the vet prescribes a course of treatment, it is important this is completed, even if the animal appears better after only one or two doses.

If the course has not been completed, some bacteria may have survived and there is a danger the animal may relapse. More importantly, the surviving bacteria are the ones that are the least susceptible to the antibiotic, which leads to selection of a resistant strain of bacteria.

There are seven main routes to administer animal medicine:

• Subcutaneous injection (S/C or sub-cut) – under the skin
• Intramuscular injection (I/M) – into the muscle
• Intravenously (I/V) – into the vein (this is a vet-only procedure)
• Oral drench
• Pour-on – onto the skin
• Intramammary – up the teat (for mastitis or dry cow treatments)
• Topical (spray, eye ointment)

Each medicine used on farm will have its own recommended route of administration. Check the label on the bottle and read the data sheet, even if the medicine has been used before.

• Record the date, dosage, and withdrawal period of the product, and the animal treated
• Complete the full course prescribed by the vet or RAMA
• Only use medicines that have been stored at the correct temperature and are not contaminated by dirt or other medicines
• Adhere to withdrawal periods
• Do not use medicines that are past their expiry date
• Dispose of unused or expired medicines safely
• Report any adverse reactions or treatment failures to your vet or the Veterinary Medicines Directorate
• Medicines should only be used in line with the guidance provided in the veterinary health plan for specific clinical signs and disease conditions. If any other disease signs are observed, a veterinary surgeon should be consulted
• Antibiotics should only be used for disease control until alternative methods are fully implemented or where there are no effective alternative ways to control disease
• The number of animals receiving antibiotics should be kept to the minimum – the smallest possible number of animals should be treated, but the health and welfare of at-risk animals should not be compromised
• Early isolation of animals showing signs of disease can reduce its spread, minimising the number requiring antibiotic treatment

If you would like to order a hard copy of Using medicines responsibly, please contact publications@ahdb.org.uk or call 0247 799 0069.