Veterinary medicines for livestock
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Keeping records for medicines used on animals to stop residues getting into the food chain, and how to report adverse reactions
The use of veterinary medicines on farm animals is controlled under European law. This covers the initial authorisation of a veterinary medicine, its use on farms and how long after any particular treatment an animal or its food products may be used for human consumption.
The legislation aims to protect consumers by stopping unacceptable levels or concentrations of residues from veterinary medicines getting into the food chain. Maximum Residue Limits (MRLs) and withdrawal periods are set as part of achieving this objective.
This guide outlines MRLs, veterinary medicine withdrawal periods, how to keep food for human consumption safe and the legislation that applies. It also discusses residue surveillance monitoring and inspection, as well as where to find up to date information such as the National Office of Animal Health (NOAH) withdrawal period tables.
It also tells you how to identify veterinary medical products, keep records for the veterinary medicines used on your animals and how to reduce the development of drug resistance. Finally, it gives guidance on how to report an adverse reaction to a veterinary medicine and what to do if you want to use organic standards for your animals’ withdrawal periods.
Legal background and identification of veterinary medicines
There are two major pieces of domestic legislation that apply to the use of veterinary medicines on farms and the control of residues. They are:
- the Animals, and Animal Products (Examination for Residues and Maximum Residue Limits) Regulations 1997 as amended (the ‘Residue Regulations’)
- the Veterinary Medicines Regulations 2013
The Residues Regulations help Britain fulfil an EU requirement for all member states to have a system of surveillance for checking residues of veterinary medicines in foods of animal origin. They give authorised officers powers to:
- inspect and examine animals and take samples for analysis
- inspect records on farms
- carry out follow-up investigations on farms when residues above statutory or other limits are detected
The Residues Regulations ensure that the process of authorising veterinary medicines is working correctly and veterinary medicines do not result in residues above the relevant Maximum Residue Level. The surveillance also helps detect if unauthorised substances are being used in food-producing species.
Under the Veterinary Medicines Regulations 2013, it is an offence to give any veterinary medicine to your animals unless those medicines have a marketing authorisation for their use in the UK. Veterinary medicines whose active ingredients have been evaluated for residue safety can be used, and your veterinarian must keep records of their use. These regulations also allow your vet to give other products under a ‘prescribing cascade’. This is allowed when no medicines are available for an illness and the animal’s suffering must be prevented.
The cascade has three levels:
- level 1 - use of a UK-authorised veterinary medicine indicated for the same species but for another condition or indicated for use in another species
- level 2 - use of a UK-authorised human medicine or veterinary medicine authorised in the EU but not the UK. This requires a Special Import Certificate
- level 3 - specially prepared medicine made by a veterinary surgeon, pharmacist or suitably authorised manufacturer
If a Veterinary Medicinal Product (VMP) is used outside its authorised uses under the cascade, a vet must specify an appropriate withdrawal period. The statutory withdrawal period for VMPs must not be less than:
- seven days for eggs
- seven days for milk
- 28 days for meat from poultry and mammals, including fat and offal
- 500 degree days for fish meat
How to identify VMPs
The possession, administration to animals, or supply of unauthorised medicines is illegal under the Veterinary Medicines Regulations. Therefore, it is important to become familiar with the labelling of veterinary medicines so you can determine those that are legal, those that are not and those that are questionable.
In the UK, the labelling of an authorised VMP is in English. While companies are allowed to use multi-lingual labels, one of the languages must be English. VMPs also need to carry the UK marketing authorisation number. This can be identified by the letters Vm, Vh or PL. These letters are followed by a five-digit, an oblique ( / ) and a four-digit code. Marketing authorisation numbers will look like this:
- Vm 09011/2001
- Vh 18705/2563
Products showing these codes or those with a prefix of EU - which are authorised throughout Europe - can be used.
Anyone who sells veterinary medicines should also remind their clients about all the responsibilities under these regulations, including the importance of record keeping.
You can get two laminated wall posters on residue requirements and regulation materials for use on your farm - one covers red meat while the other covers poultry and eggs. To order your copies, write to:
Veterinary Medicines Directorate
Alternatively, you can call the Veterinary Medicines Directorate Helpline on 01932 336 911.
What is a Suitably Qualified Person?
Suitably Qualified Persons (SQPs) are a group of professionally qualified individuals who are allowed to prescribe and/or supply certain VMPs under the Veterinary Medicines Regulations. To qualify as an SQP, you must take training and pass exams, then register with an approved registration body in order to practice. At this time, the Animal Medicines Training Regulatory Authority (AMTRA) is the only register available for SQPs.
Food safety and Maximum Residue Limits
The Maximum Residue Limit (MRL) is the highest level or concentration of a residue from an active substance that is legally permitted or acceptable in a foodstuff, such as meat, milk, eggs, or honey. The residue may consist of the parent substance that was administered to the animal and its ‘metabolites’. Metabolites are the substances that the animal has converted the parent substance into.
MRLs are set by the regulatory authorities after evaluating the results of a pharmacological and toxicological studies on the particular substance (see setting MRLs and withdrawal periods).
The withdrawal period is the period of time regulatory authorities have set between giving the animal its last dose of veterinary medicine, and it, or its food products, being allowed into the food chain. If you observe the correct withdrawal periods you should prevent consumers being exposed to residues from veterinary medicines at concentrations greater than the MRLs.
However, for the same species and same veterinary medicine, there may be different withdrawal periods for the different foodstuffs. The withdrawal period is included in the veterinary medicine’s Summary of Product Characteristics (SPC), labels and package leaflet - which should be part of the product packaging.
The law relating to the use of veterinary medicines, keeping records of their use and following the prescribed withdrawal periods is there to ensure that MRLs are not exceeded and so consumers are protected. If a residue of a veterinary medicine is at a concentration below the MRL, then it does not pose a threat to consumer health. Therefore, supplying treated animals for slaughter before the withdrawal period has been observed or supplying food products from them that contain residues above the relevant MRLs are offences.
Finding the correct withdrawal period
A full and up-to-date database of authorised veterinary medicines is available online on the VMD website. This database includes the SPC for each product and the respective withdrawal periods. Find the VMD Product Information Database on the VMD website.
You can also find information on animal medicine withdrawal periods on the NOAH website. This information is also available in print format as an annual book. Both versions include product data sheets for animal medicines. However, not all pharmaceutical businesses are members of NOAH, so the compendium does not list all authorised medicines.
How does the VMD determine withdrawal periods?
Setting the withdrawal periods is considered to be a multi-stage, scientific process. See our flowchart for the VMD withdrawal periods.
The first three steps of this scientific process are conducted at a European level by the European Medicines Agency (EMA). The VMD is involved in this work as the UK’s Veterinary Medicines Regulatory Agency and member of the EU Committee for Medicinal Products for Veterinary Use. Step 4 is conducted both at National and European levels and the VMD is involved in the determination of withdrawal periods for all veterinary medicinal products authorised for use in the UK.
Step 1 Identify No Observed (Adverse) Effect Level (NO(A)EL) samples
A range of scientific studies are conducted on laboratory animals using the active substance that will be used in a VMP and from the results the highest dose (of the active substance) that does not cause observed adverse effects is identified. This is referred to as the NO(A)EL.
Step 2 Determine the ADI
The NO(A)EL is divided by an ‘uncertainty factor’, typically 100-1000. This uncertainty factor is to allow for extrapolation between species, differences between individuals and to compensate for other uncertainties in the data. The figure determined is referred to as the Acceptable Daily Intake or ADI. The ADI is the amount of a residue that is considered safe for a person to eat every day over a lifetime.
Step 3 Establish MRLs
The MRL is then set by dividing the ADI amongst all the edible tissues (muscle, liver, kidney, fat/skin) and edible products, (milk, eggs, honey), taking account of:
- how much of a particular food may be eaten each day- this is called the ‘food basket’
- how much of the active substance and/or its metabolites occur in each food substance, and how it is distributed in the animal’s body
- how and how much of the active substance is metabolised in the animal’s body
- identifying the appropriate ‘marker’ for intake calculations - this may be the parent compound or a metabolite - this is referred to as the ‘marker residue’
A limit is then set for the marker residue in each edible tissue and edible product ensuring that the ADI is not exceeded - these limits are the MRLs.
Step 4 Determine withdrawal periods
The time that must elapse after the last treatment of a veterinary medicine before an animal can be slaughtered, or the animal product can be taken for human consumption is calculated from data collected in scientific studies. These studies determine how rapidly the marker residue is depleted from edible tissues and edible products, and how quickly the levels of the marker residue fall to below the MRLs. Sometimes an ‘uncertainty factor’ is included in the determination to allow for inconsistencies in the data and differences between individual animals. This period of time is referred to as the withdrawal period. A withdrawal period is set for each VMP intended to be used in food producing species, so that the residues in each food will be below the relevant MRL and, therefore, ensure no risk to consumer health.
Avoiding veterinary residues in food
There are several simple steps that as a farmer, you can take to avoid unacceptable residues in food of animal origin.
- maintain close communication with their vet about the safe and appropriate way to use veterinary medicines
- give animals the appropriate dose, based on actual body weights
- use only veterinary medicinal products that are authorised in the UK for the specific purpose, or that are prescribed under the cascade
- buy medicines from recognised sources, such as vets, veterinary pharmacies or animal health retailers
- follow the instructions for use on the product label and package leaflet, unless directed otherwise by a vet
- apply the appropriate withdrawal periods, as specified in the product’s instructions, unless the product has been prescribed under the cascade
- consider if there is a risk of cross-contamination between treated and untreated animals and their feed
- keep correct records
- ensure that any farmed animals sold are accompanied by their medicines treatment history and not send them if their treatment history is unknown
- not treat animals with medicines that are not authorised for use in food-producing species such as phenylbutazone, an anti-inflammatory medicine
- not use out-of-date medicines - it is an offence to supply an out-of-date medicine
Residue monitoring and inspection
The VMD operates a statutory surveillance programme that fulfils the UK’s obligations to the EU Directive 96/23/EC. This directive requires EU member states to analyse food samples for residues of veterinary medicines, unauthorised substances and environmental contaminants. The programme covers red meat, poultry, salmon, trout, eggs, wild and farmed game, honey, and milk. Over 35,000 samples are collected for analysis each year. They are collected from farms, egg-packing stations, abattoirs and meat-cutting plants.
You can [read about the surveillance programme and see published results on the VMD website].(http://www.vmd.gov.uk/fsf/residues_nonstat.aspx) The Veterinary Residues Committee (VRC) advises on the surveillance programme. Find VRC information on the VRC website.
The results of the surveillance programme indicate that the UK-authorised uses of veterinary medicines do not result in unacceptable residues. However, where the instructions for use are not followed, residues above the MRL can result.
Action taken where unacceptable residues are detected
Under normal circumstances, action is taken where a residue of an authorised veterinary medicine is detected at a concentration above the MRL. An authorised officer, such as a vet or Fish Health Officer carries out a thorough on-farm investigation at the farm of origin to discover the source of the residue. The farmer and their own veterinary surgeon can then be given advice to help avoid a recurrence.
Where very high concentrations of authorised substances or unauthorised substances are detected, an investigation will be undertaken by an Investigation Officer from Defra’s Rural Payments Agency (RPA). The VMD may prosecute if there is sufficient evidence of misuse of an authorised product or use of an unauthorised substance. Animals on the farm that are shown to contain residues of unauthorised substances could be destroyed.
Using withdrawal period tables for veterinary medicines
The NOAH withdrawal period tables are multiple A-Z tables. They contain information on all authorised veterinary medicines from companies registered with NOAH, the manufacturing company, the species it is used for, the withdrawal period and any contraindications or usage instructions involved. You can refer to these tables to get an overview of some of the different products. It is very important that you check the latest information for each product you intend to use on the Veterinary Medicines Directorate (VMD) website and follow the advice set out on the product label and package leaflet.
It is essential that the correct withdrawal period is observed. For the most recent information on the correct authorised withdrawal period, you should also search the VMD Product Information Database on the VMD website.
Each table shows a specific animal, meat or product with their corresponding withdrawal periods. The word ‘nil’ indicates that no withdrawal period is needed. The animals and their products include:
- cattle milk
- cattle meat
- sheep meat
- pig meat
- poultry meat
- fish meat
Your vet should set a withdrawal period of at least 28 days for meat when intramammaries are used outside the Summary of Product Characteristics (SPC) recommendations, including when:
- the treatment period is increased
- the number of tubes is increased
- the interdose interval, or time between doses is shortened
- the treatment is changed to another product
- simultaneous dosing of other antimicrobials
Specific considerations for milk
Milk should be left out from the bulk sold if you have any cows that are in poor health such as those with:
- udder or reproductive tract diseases
- a diet that contains any substance that can make milk unsuitable
- low milk yields of less than two litres a day
Milk withdrawals for goats and sheep will be found under the ‘notes’ column.
Your vet should set a withdrawal period of not less than seven days for milk when intramammaries are used outside the data sheet recommendations, including when:
- the treatment period is increased
- the interdose interval is shortened
- the number of tubes is increased
- the treatment is changed to another product
- simultaneous dosing of other antimicrobials
Withdrawal periods for dry cow preparations
In the tables, some dry cow medicines are given two withdrawal periods. The ‘cattle milk’ column is the number of hours that follow a dry period that’s at least as long as the Minimum Dry Period (MDP). A second figure that shows in the ‘cattle milk’ column is the minimum amount of time between the product’s infusion into the dry udder and the cow’s calving date.
If calving takes place before the expected date, you will need to extend the withdrawal period. This is to combine the remaining expected MDP along with the milk withdrawal from the last treatment.
If you give dry cow medicines outside of the SPC, you should confirm the absence of antimicrobials before using the milk for human consumption.
Anthelmintic and antimicrobial use and drug resistance
Antimicrobial and anthelmintic drugs play an important role in treating disease in animals. Antimicrobials are used to treat, control or prevent bacterial, fungal, viral and protozoal-based diseases. Anthelmintics, or ‘wormers’, are used to treat various helminth species - also known as worms - such as the liver fluke, roundworm and tapeworm.
Antimicrobial resistance and use of antimicrobial drugs
Resistance occurs when the micro-organism that an animal is being treated for becomes resistant to an antimicrobial that normally kills it. The resistance can occur because:
- Micro-organisms may not have, or no longer have, the cellular sites where an antimicrobial will act. They could also have special enzymes that block the action of the drug, or a pump that pumps the antimicrobial out of the cell.
- A spontaneous mutation occurs that changes genes on chromosomes without adding new genes. As more antimicrobials are used over time, more resistance takes place as the mutated genes prevent the drugs from working.
- Mobile genetic elements known as plasmids, transposons and integrons - which carry antimicrobial resistant genes and can easily move from one cell to another - are active. Genetic information is shared and is the major way to develop multi-drug resistance.
There are other ways the antimicrobial resistance can occur. Overuse and inappropriate use of antimicrobial drugs may kill off bacteria, but if any of these micro-organisms have even small amounts of resistance, they can survive and continue the cycle of growing resistance.
How to reduce antimicrobial resistance
There are a number of steps that you, as a farmer or vet can take to reduce antimicrobial resistance. You must:
- use good herd or flock health and biosecurity practices, hygiene, good nutrition and animal comfort
- use antimicrobials early in a disease when the clinical signs are first diagnosed
- use a narrow spectrum antimicrobial rather than a broad spectrum one
- if more than one antimicrobial is needed, use the one that is least important for human therapy and the least likely to select for resistance
- understand the product’s literature thoroughly
- follow the product’s labelling instructions, most importantly the dosing instructions - the amount of antimicrobial and how many times it should be administered
- perform sensitivity testing on causal bacteria against those antimicrobials of choice
- re-evaluate the benefit of any preventative antimicrobial use from time to time if no benefit is seen
Anthelmintic resistance and use of anthelmintic drugs
Anthelmintic resistance is seen in sheep and goats and to a lesser extent, horses and cattle. There is growing multi-drug resistance in some areas that means farmers are left with solutions like clearing their land and restocking at a later time or moving into other business areas altogether.
Why is the resistance occurring?
There are numerous reasons as to why anthelmintic resistance is occurring. These include:
- heavy use of the same or different anthelmintics on money farms
- continued use of anthelmintics which has caused a more resistant population of worms
- increase in the population of resistant worms
- some farmers using lower doses of anthelmintic drugs
- poor knowledge of the various classes of anthelmintics and the use of worm control strategies
- misdiagnosis of symptoms that lead to overuse or inappropriate use of the drugs when they’re not needed
How to reduce anthelmintic resistance
In order to reduce anthelmintic resistance, farmers and their veterinarians should develop good worming strategies and practices. These include:
- developing a health plan with a vet or Suitably Qualified Person (SQP)
- using the right drug at the correct dose for the specific worm, based on the advice of the veterinary surgeon or SQP
- performing a slow annual rotation of the drugs used
- avoiding worming to a set pattern, but instead looking at current worming patterns and making adjustments based on veterinary or SQP advice
- performing regular faecal egg count testing and adjust the worming programme accordingly
- reporting any suspected adverse reactions to the drugs used to the vet or SQP
- reporting adverse reactions to the VMD using form MLA 252A - more commonly known as the ‘yellow form’
- arranging specialist investigations to find out if this is a resistance problem or lack of efficacy of the drug used
- using ‘safe’ pasture developed from new pasture land, or hay or silage fields
- considering using non-susceptible adult stock that are bred for resilience to infestation in order to reduce worm populations in pastures and thus, frequent treatments
- treating all new animals with anthelmintics from two classes with the lowest known resistance levels
- quarantining the animals after treatment and then releasing them on to pasture land contaminated with worms to avoid importing resistant worms
Record keeping for veterinary medicines
You must keep records for your veterinary medicines, as this provides traceability for specific batches of products. You also have to have all your proofs of purchase for the veterinary products you have bought for your food-producing animals. Your vet must also provide you with information of any medications that you have given to your food-producing animals. You need to record the disposal of veterinary medicines that have not been used. These activities are required by law.
You must keep all records and proofs-of-purchase for at least five years following the administration or disposal of the product, even if the animals involved have been slaughtered or have died during that period. All records must be in writing, capable of lasting for a prolonged period of time, permanent and available on request by anyone who is in an enforcement capacity. You can also keep electronic copies of these records.
Adverse event reporting
An adverse event is any observation in animals or humans, whether or not considered to be product-related, which is unfavourable and unintended and which occurs after the use of, or exposure to, a veterinary medicinal product.
The science and activities relating to the detection, assessment, understanding and prevention of adverse effects, or any other medicine-related problem, are known as pharmacovigilance. Adverse events include:
- adverse reactions in animals that occur after use according to label instructions and after off-label use
- suspected lack of expected efficacy after use according to the label instructions
- adverse reactions in humans after exposure to a veterinary medicine or treated animal
- adverse effects in non-target animals, humans or plants when exposed to veterinary medicine in the environment
- concentrations of veterinary medicine residues in tissues or food products of treated food-producing animals higher than the maximum residue limits when the recommended withdrawal period of the given veterinary medicine has been followed
Anyone can report an adverse event in reaction to a veterinary medicine to the Veterinary Medicines Directorate (VMD), including:
- animal owners
- veterinary surgeons
- veterinary nurses
- Suitably Qualified Persons
- marketing authorisation holders - they have a legal obligation to report serious adverse events to the VMD involving prolonged severe clinical signs or death within 15 days following the receipt of information
All suspected adverse events should be reported to the VMD using form MLA 252A - more commonly known as the ‘yellow form’. You must use this form when a suspected adverse reaction is observed in animals or humans during or after the use of a veterinary medicine. Report an adverse reaction online or download form MLA252A from the VMD website.
The yellow form can also be obtained by contacting the VMD at the following address:
Veterinary Medicines Directorate
You can also call the VMD helpline on 01932 338427 or email them at firstname.lastname@example.org.
All reports received by the VMD are recorded on a database. Additional information may be requested, such as laboratory or post mortem reports, in order to assist in determining the causal relationship between the veterinary medicine and the adverse event. All reports of suspected adverse events are reviewed by a group of VMD veterinarians, toxicologists, ecotoxicologists, immunologists and pharmacists, and all serious adverse events are further examined by the Veterinary Products Committee (VPC). Adverse events in humans are reviewed by the Appraisal Panel for Human Suspected Adverse Reactions to Veterinary Medicines, a sub-committee of the VPC. VMD representatives also take part in the European Pharmacovigilance Working Party. This group monitors and harmonises adverse event reporting in the European Union (EU).
If there is a pattern of adverse events for a particular product, regulatory actions will be initiated. Such actions include:
- addition of warnings to the labels and literature of the product
- changes in the authorised use of the product
- batch or product recall
- removal of the product from the market until safety issues are resolved
- suspension of the right to manufacture the product
Others who need to keep records
There are other individuals who need to keep veterinary medicine records. These are:
- persons allowed to supply veterinary medicinal products on prescription
- holders of manufacturing authorisations
- wholesale dealers
- approved distributors of feed stuffs or premixtures
Keeping records for horses
EU legislation defines a horse as a food-producing animal. Therefore, if you keep horses, ponies, donkeys, zebras and Przewalski’s horses for human consumption, you need to maintain records for your purchases of all veterinary medicines and their administration in the animals’ passports. The passports are important because they make certain that if the animals have been treated with certain medicines, they are not used as food for human consumption.
Also, since 1 July 2009, foals must have a passport and also be microchipped. This needs to be done before the foal is six months old or by 31 December in the year it was born, whichever comes later.
See our guide on horses on farms.
Further information on withdrawal periods for livestock veterinary medicines
There are several organisations that can offer advice on withdrawal periods for livestock medicines, as well as specific guidance on livestock.
The Veterinary Medicines Directorate (VMD) is an Executive Agency of the Department for Environment, Food and Rural Affairs. The VMD’s goals are to protect animal health and welfare, public health and the environment by assuring the safety, quality and efficacy of veterinary medicines. The VMD also develops, updates and enforces the legislation surrounding veterinary medicines, controlling them from their point of manufacture to their supply process and final administration. For further information, you can call the Veterinary Medicines Directorate helpline on 01932 336 911.
The General Pharmaceutical Council (GPhC) is the independent regulator for pharmacists, pharmacy technicians and pharmacy premises in Great Britain. You can contact them on their enquiry line on 020 3365 3400 or email them via their website
Alternatively, you can write to them at the following address:
The General Pharmaceutical Council
129 Lambeth Road
London SE1 7BT
AMTRA is an independent regulatory body whose task is to ensure that the marketing and distribution of animal medicines in the UK is undertaken in a responsible manner by AMTRA qualified persons. Currently, it is also the only body to hold a register for Suitably Qualified Persons. You can call the AMTRA helpline on 01359 245 801 or email them at email@example.com. Alternatively, you can write to them at the following address:
Animal Medicines Training Regulatory Authority
Unit 1C, Woolpit Business Park
Bury St Edmunds, IP30 9UP
One of the major roles of the Department for Environment, Food and Rural Affairs (Defra) is to help the farming industry operate as efficiently as possible. Defra administers European Commission support policies that provide around £3 billion to UK agriculture. They also oversee a number of agencies that work with arable farmers, imports and exports of crops, and implement pest and disease controls. You can call the Defra helpline on 08459 33 55 77.
The RPA is responsible for licences and schemes for growers as well as for running the Single Payment Scheme (SPS). For information about the SPS and how it can help your farming business, you can call the RPA Helpline on 0845 603 7777.
You can also read the guide on the SPS.
In England, the Farm Advisory System advises farmers about cross compliance. For further information call the Cross Compliance helpline on 0845 345 1302. Alternatively, find information on cross compliance requirements on the Cross Compliance website.
The National Farmers Union (NFU) represents the farmers and growers of England and Wales. It aims to promote successful and socially responsible agriculture and horticulture, while ensuring the long-term viability of rural communities.
Farmers are likely to come into contact with local authorities over a number of farming, land-use, food standards and environmental regulations. Your local authority may also be able to provide further information or resources.
020 8367 3131
RPSGB Enquiry Line
020 7735 9141
01359 245 801
08459 33 55 77
0845 603 7777
Veterinary Medicines Directorate Helpline
01932 336 911
Cross Compliance Helpline
0845 345 1302
Published: 29 August 2012
Updated: 13 June 2013
- Fixing references to specialist guides
- Minor correction - in 'specific considerations for milk', the milk withdrawal period previously showed incorrect. The correct period is "not less than seven days".
- First published.