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Storage and safe use of medicines on farm
  1. John Carr and
  2. Jenny Smith

Abstract

To ensure the safety of staff and animals on farm, all medicines need to be stored in a safe place, labelled appropriately, kept at the recommended temperature, transported carefully and administered according to the manufacturers' instructions. Giving examples of both good and bad practice, John Carr and Jenny Smith describe the precautions that should be taken by farm staff and veterinary surgeons when handling medicines to maintain a safe working environment and provide the best animal care.

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John Carr graduated from the University of Liverpool in 1982. He worked in general practice before returning to Liverpool where he was the Leverhulme resident in pigs. After obtaining a PhD, he spent some time teaching pig medicine in the UK, USA and Australia; he currently works as an international pig health consultant. He holds a European diploma in pig health and management, as well as the RCVS diploma in pig medicine, and is a RCVS recognised specialist in pigs.

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Jenny Smith graduated from the University of Bristol in 2008. She then worked for a dedicated farm animal practice in Devon. Her main interests lie in serving commercial pig clients, providing a small-holding pig service and developing biosecurity procedures on farms. In 2010, she joined the Royal Army Veterinary Corps as part of the Territorial Army; in 2012, she was commissioned as a Veterinary Officer.

Medicine care on farm

In addition to the appropriate selection of medicines, it is vital that veterinary surgeons on farm also provide advice on the security, storage, hygiene, use and disposal of pharmaceutical products. It is important that standard operating procedures are in place to fulfil these criteria. Reviewing the use of medicines is an essential part of any herd health maintenance programme.

Medicine security

Placement of medicines around the farm

Medicines must be placed in a secure location away from children, animals and thieves. The medicine store must be kept in a lockable area. If medicines are in an open facility, the medicine store itself must be lockable. Medicines should only be accessible to authorised staff (Box 1).

Box 1: Medicine security: placement around the farm

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Medicines used around the farm must be returned to the secure medicine store or placed under lock and key around the farm. All medicine storage requirements (eg, temperature) should still be met for any product that remains on farm but out of the main medicine storage area.

Medicine security must be extended to include in-feed and in-water medicines as well. All feed bins should be numbered clearly and their position marked on a site map. When using feed medication in bags, you should consider colour coding the bags or the food.

The delivery of medication through water systems should be designed, numbered and managed to avoid medication mistakes. The water system also needs to be secure in order to avoid interference from the general public or animals.

Animal identification systems

It is essential that the correct animals are treated with the correct medicine. To do this, you should ensure that the farm, group/pen, and the individual animal is clearly identified for the duration of the withdrawal periods (Box 2), and the use of any medication should always be clearly recorded.

Box 2: Medicine security: animal identification systems

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Medicine storage

Temperature requirements

Many medicines have specific storage temperature requirements (Box 3), so during a routine farm veterinary audit, the temperature of all medicine stores should be checked and recorded. On a day-to-day basis, the farm medicine areas should have maximum and minimum thermometers, and these should be monitored regularly and the readings recorded. There are three main types of storage:

  • Frozen medicine storage;

  • Cold medicine storage;

  • Ambient medicine storage.

The temperature within refrigerators varies; the coldest area is at the top, getting increasingly warmer towards the bottom of the unit. A temperature of 2°C to 8°C is only maintained in the body of the refrigerator. Ensure that the medicines are correctly placed in the refrigerator

Typical medicine storage log from a functional cold refrigeration store. The blue-tinted area represents the ideal temperature of 2°C to 8°C

Box 3: Medicine storage: temperature requirements

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Frozen medicine storage

Most medicines that require freezing will be fine at –20°C. A small number of medicines require a temperature as low as –70°C, but this is generally impractical; most practices don't have access to suitable refrigeration systems at this temperature.

Cold medicine storage

Cold medicine stores are used to keep products at between 2°C and 8°C. Many medicines on farms, including vaccines and open medicine bottles, have specific requirements to be kept within this range (Box 4).

Box 4: Medicine storage: cold medicine storage

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Remember that refrigerators may not be running at the correct temperature. If vaccines are subjected to freezing, their activity is generally significantly reduced and they may be rendered useless.

Ambient medicine storage

Most medicines, including injections and in-feed/in-water antibiotic medications, have specified requirements to be stored below 25 to 30°C. Therefore, it is always important to check the label.

In many parts of the world, including the UK, summer time temperatures may exceed 30°C. It is important to note that the inside of a car may also exceed this temperature, making it an unsuitable place to store medicines.

Most farms do not provide any specific warm medicine storage facilities. These are required for medicines that need to be stored at ‘room temperature’.

Health and safety

Certain products may need to be kept more securely than others, so that if the bottle falls and breaks the medication does not come into contact with human skin. Prostaglandins are a classic example of a product that should be stored in a place where accidental exposure cannot occur. Inappropriate handling of medicinal products can expose staff to potential sharp and stick injuries. Specifically, needles should not be left in the tops of medicine bottles (Box 5) or in woodwork around the farm. Therefore, consider providing training on medicine handling and storage to all farm staff, which increases the value of having a vet on the farm health team. Also remember that data sheets should be collected in an accessible file and kept up to date.

Box 5: Medicine storage: health and safety

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Medicine hygiene

Medicines should be stored in a clean state (Box 6). On-farm medicines are sometimes stored extremely poorly, which can result in contaminated tops and seals. This can lead to abscessation or even gangrene following injections. All of the tops of injection products should be protected between uses and wiped clean before use. Vaccines should be used within 24 hours of opening the bottle so the bottle top should always be clean. Avoid multiple hole damage to bottle tops, as this facilitates the entry of dust and other materials.

Box 6: Medicine storage: hygiene

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Syringes and needles used for injections and any oral medication preparations must be thoroughly cleaned before use. Needles must not be damaged or blunt as this will cause additional tissue damage. If possible, the use of needleless syringe technology should be encouraged.

Feed must be stored appropriately to ensure that any included medication is not affected by feed hygiene or storage issues. Mould can affect the life span of medicines as well as vitamin availability. Mycotoxins may also affect the treated animal's immune system, reducing the effectiveness of vaccine programmes. If insects, rodents and birds eat medicated feed this leads to environmental contamination, so access to feed stores needs to be actively restricted.

Monitoring medicine storage temperature

If you suspect a problem with the temperature of a medicine storage area, a remote temperature data logger should be used to monitor the area for about a week. Place one logger on the outside of the medicine storage area and another inside the store itself. The location of the logger can be critical to obtaining an accurate reading. Cold refrigerators have no warming element and, if the room temperature drops below freezing, the temperature of the cold medicine store will eventually equilibrate with the ambient external temperature. How long it takes for this to happen will depend on the insulation properties of the store.

The medicine temperature report should include some simple measurements, including the maximum, minimum and average temperatures and the percentage of time for which the medicines were stored above or below the acceptable temperature requirements.

It is vital that any temperature maintenance system has air circulation so that the store temperature is evenly distributed. In many stores, medicines are overstocked or products remain in their outer delivery boxes. This leads to restricted air movement around the medicine products, leading to uneven or inadequate cooling. If possible, you should advise the client to purchase a medicine refrigerator.

It is important that any other storage requirements for specific products (eg, keeping the product out of direct light) are adhered to. Use-by dates should also be respected.

Water quality can affect the solubility of medicines. In particular, the pH and the presence of minerals and other chemicals in the water can inactivate medicines. After use, check the bottom of the water medication equipment to ensure that the correct dose has been achieved and that no residual medicines are present.

Take care when using any washing materials to clean the water supply, feeding system or general medicine store. These washing agents may require chemical waste disposal.

Contamination by pathogens

Medicine products can become contaminated by pathogens, which can, in turn, facilitate the spread of pathogens further (Box 7). Human food products must not be stored in a medicine store. They pose a risk to the animals being medicated and to the staff who consume the foods. Medicine stores should be regarded as chemical stores and additional food storage facilities should be made available for staff.

Box 7: Medicine storage: contamination by pathogens

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Medicine use

Records of the purchase and use of medicines must be maintained by the veterinary practice and farm. All-in/all-out batching methods allow medicines to be analysed easily by the veterinarian using standard computer spreadsheet software.

Scrutinising medicine use has become more important as part of various auditing programmes. For example, the Danish monitoring programme has instigated the use of a ‘yellow’ and ‘red’ card system to warn pig farms who have used medications in excess of company standards (see www.vetstat.dk for more information).

Age of products

All medicine products used on farm must be administered according to their data sheets and any labelled instructions. The age of the product, date of seal breach and date of use of the product should all be recorded. Many products are sold in quantities that cannot be used by the farm team within the ‘once open use by date’. Batching programmes and planning are, therefore, necessary to avoid misuse of medications. The use of out-of-date products is illegal and, if any such products are found, they must be removed from the farm.

Administration route

Ensuring that all medications are administered appropriately is an important part of the veterinary audit. Needle length and gauge are important considerations, both for the welfare of animal(s) and the efficacy of the medication. For example, the use of a short needle may place the medication into subcutaneous fat, resulting in poor vaccination in adult pigs.

When in-feed and in-water routes are used to provide medication, vets should ensure that there is sufficient space for all of the animals to receive equal amounts of medication (Box 8). You also need to make sure that the systems are all in working order. Leaking drinkers and feeders that waste feed into the slurry system result in financial losses and contribute to environmental contamination with medicinal products.

Box 8: Medicine use: administration route

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Farms intending to home mix veterinary medicines must first seek approval from the Veterinary Medicines Directorate (VMD).

Accidents involving staff

Standard operating procedures should be in place to ensure that prompt and appropriate first aid action is taken if there are any medicine accidents or emergencies involving staff. All staff who suffer an injection or sharp injury should seek medical attention and should take with them details of the veterinary practice, the bottle of medicine concerned and its data sheet. Where oil-based vaccines are involved, it is essential to make sure that the attendant physician takes the matter extremely seriously. The injured member of staff must not be allowed to drive themselves to the medical centre, but must be accompanied to hospital.

Although not a legal requirement, it is recommended that all adverse events in humans (such as accidental self-injections) involving veterinary medicines be reported to the VMD. Downloadable report forms and an interactive form for completion and submission online are available at www.vmd.defra.gov.uk.

Accidents involving animals

Withdrawal period

A key component of medicine use is adhering to the appropriate medicine withdrawal periods. This depends on the country where they are being used as different countries may have different time frames. This can be extremely significant when dealing with export markets. Ensure that animal identification methods allow all medicated animals to be easily and readily identified.

If a product is used under the prescribing cascade, the vet should determine an appropriate withdrawal period. If a product is administered to a species not identified in the product literature, or to an authorised species at a higher than recommended dosage, it is necessary to apply at least the minimum statutory withdrawal periods or the withdrawal period stated in the product literature – whichever is longer. The minimum statutory withdrawal periods are seven days for eggs and milk, 28 days for meat from poultry and mammals, and 500 degree days (calculated by dividing 500 by the mean temperature of the water in °C) for meat from fish.

For some substances, withdrawal periods that are longer than the statutory minimum withdrawal periods may be appropriate. Veterinary surgeons should use their knowledge and experience in deciding exactly what the length of time should be.

Broken needles

A standard operating procedure should be in place to guide staff on how to proceed with broken needles. Unless adequately marked and identified, the animal, which contains a fragment of the needle, must not be allowed to enter the human food chain.

Responsibilities

The Royal College of Veterinary Surgeons (RCVS) has published recommendations on the storage of medicines within the practice and its vehicles. For further details, review the RCVS's Practice Standards Guidelines and the BVA's Good Practice Guide on Veterinary Medicines. Farmers must be informed that they need to keep records of any medicine treatment in animals for five years. The VMD's web page, www.vmd.defra.gov.uk/index.aspx, has information on record-keeping requirements for farmers and veterinary surgeons, pharmacovigilance and the use of the prescribing cascade.

Disposal of medicinal products

Medicine security must include the safe disposal of all medicinal products, including needles and syringes as well as empty or partly used products (Box 9). Medicines cannot be placed in the normal landfill waste collection, and farms must be encouraged to use suitable containers for sharps.

Box 9: Disposal of medicine products

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Feed bins and water medication containers must be cleaned appropriately and the cleaning water disposed of according to local waste management regulations.

Adding value

Veterinary advice about medicines used on farm is often neglected. Farmers and staff may receive limited specific training in how to manage and dispose of medicines, so it is essential that the management and disposal of medicines are a priority for the attending veterinary surgeon.

A focus on this area of farm practice provides an opportunity for the veterinarian to add value to the farm team by providing appropriate training, helping draw up standard operating procedures and ensuring the best use of medicines for animal health while minimising costs.

Further reading

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Footnotes

  • Provenance: Commissioned

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