What pet owners need to know about medicines


Much of an animal’s medical treatment will be administered by the owner at home. To do this safely and effectively, owners need information about why and how to use the treatments. This module discusses what sort of information owners need, what is required by law, what is available, and how it can be provided in the veterinary practice. 

If a medicine is not used correctly, the intended benefits of the treatment might be lost. This can lead to disease progression, owner dissatisfaction with treatment, reduced quality of life for the animal, and increased treatment costs. 

Incorrect use of a medicine can also lead to harm, even death. For example, there are many reports of owners mistakenly giving spot-on products orally; in one case this led to the death of a dog as a result of inhalation of the product (VMD 2016a).  Cats have been harmed by permethrin-containing spot-ons for dogs; and rabbits harmed by spot-on products for cats (VMD 2016a; VMD 2017a). There is also a risk of harm to people through incorrect handling or disposal of medicines (VMD 2017a).  

As well as knowing how to use a medicine, pet owners also need to know about adverse effects that might occur even if the medicine is used correctly. There is potential for grievance if owners are not informed about adverse effects (for example, in a case of uncharacteristic aggression in a dog treated with glucocorticoids, that attacked a child) (Change.org petition).

Compliance* with prescribed medical treatment, even for dedicated, concerned clients, frequently breaks down (Atkins 2014) and people tend to overestimate their own compliance (Barter et al 1996). Of 301 cases of heartworm in which dog owners felt their compliance in administering preventative products was ‘perfect’, analysis showed that 81% of owners had not purchased sufficient medication to ensure effectiveness (Atkins 2014). In a survey of cat and dog owners, while the majority administered antiparasitic drugs, most did not correctly follow the instructions on use, and so dewormed at irregular (and consequently ineffective) intervals (Matos 2015). The authors of an investigation into lack of ectoparasiticide efficacy concluded that the most likely reason for inefficacy was owners giving inconsistent treatment, as opposed to parasite resistance (Coles, Dryden 2014). 

Various factors may underlie poor compliance (Elsheikha 2016; Jin et al 2008). They include: 

  • interactions between the owner and the professional

    • language and communication barriers

    • inadequate explanation

  • poor information provision

    • information not given, not found, or not read

    • information not being in plain language

    • limited understanding and poor health literacy

  • owner behaviour

    • forgetting to give the medicine

    • ignoring or being unable to follow advice

    • poor dexterity

    • individual beliefs, concerns or expectations

    • competing priorities and costs for the owner

    • lack of support and unstable living conditions

  • treatment factors

    • complicated regimen

    • difficult administration

    • uncooperative animal.

* Several terms are used in healthcare to describe a person’s behaviour when using a medicine as prescribed, or following advice about diet, exercise or lifestyle changes (Jin et al 2008). ‘Compliance’ suggests passively following a health professional’s recommendations; ‘adherence’ implies being able and willing to abide by a prescribed regimen; and ‘concordance’ requires that the prescriber and patient have come to an agreement about the chosen regimen (Aronson 2007, Iuga 2014). These terms are often used interchangeably. In this module we use the term compliance.

There appears to have been little research into what information pet owners need in order to administer treatments effectively and safely. It seems reasonable to apply what has been learned about the information needs of people in relation to human medicines. National guidance suggests people need to know the following in order to use medicines correctly (FDA 2017, NICE 2009):

  1. What the medicine is.

  2. Why it has been prescribed and how it is likely to affect the condition.

  3. How to give the medicine to the pet and whether it should be given with food.

  4. How often to give the medicine and how much to give each time. If it is a liquid, whether to shake the container first.

  5. How long to give it, and whether the course must be finished even if the pet seems to be back to normal.

  6. How to store the medicine.

  7. What to do if the pet vomits or spits out the medicine.

  8. What to do if a dose is missed or too much has been given.

  9. Whether the medicine could interact with other medicines.

  10. What adverse reactions to watch for, and what to do if they notice any.

  11. Whether and when to return the pet for a check-up.

  12. Whether a further supply of the medicine will be needed, and how to get it.

How information is given is also important. People will have a better understanding if they are given both written and verbal instructions, rather than verbal alone (Johnson 2008; NICE 2009). The timing is also important. It should be given when the medicine is dispensed, although people are sometimes not ready to take in the information offered at that time (Murphy 2006). The advantage of written information, given with a medicine, is that it can be read after leaving the practice, when questions and uncertainties may emerge (e.g. if a dose has been missed, or an adverse effect has appeared) (Amery 1999). Prescribers should become familiar with written information that accompanies medicines and not assume that an owner will understand it all or that the information will be specific to every patient (e.g. the leaflet of an authorised medicine will not mention an unauthorised use). It is important to remind owners to read the label and leaflet. Demonstrating how to use a medicine can also help.

Veterinary medicines

The company that markets a veterinary medicine must provide certain information with the medicine – for example, indications, target species, dosage instructions and contraindications (VMD 2016b). If this information does not fit on the immediate packaging or outer pack they must produce an accompanying package leaflet (Veterinary Medicines Regulations 2013). The package and the leaflet of a veterinary medicine are approved by the regulatory authority (Veterinary Medicines Directorate [VMD] or European Medicines Agency [EMA]) as part of the licensing process and the information is based on the product’s summary of product characteristics (SPC). (For more on product SPCs, see the module Quick-reference prescribing information – what is there?

There is a standard EU template for veterinary medicine package leaflets (EMA 2017). This specifies the addition of a few specific phrases, including on reporting side effects and product disposal. However, there is no requirement for a user-friendly layout or for leaflets to be tested with users. Therefore package leaflets for veterinary medicines typically use the same wording as the product SPC (or NOAH data sheet, which is based on the SPC) and so include overwhelming detail and highly technical language that many lay people will not understand or not attempt to read. 

There is no online source of package leaflets for products authorised in the UK by the VMD. If a medicine is authorised via the EMA, any package leaflet is published within the European Public Assessment Report (EPAR) on the EMA website, although it is not easy to find and print (see the module on Quick-reference prescribing information). 

Human medicines

Since 1998, EU legislation has ensured that human patients are provided with understandable written information about medicines when they are dispensed, to aid safe and appropriate use (DTB 1995). A package leaflet (known as a patient information leaflet) must be provided if the required information cannot all be included on the packaging (Article 58 of Directive 2001/83/EC). This means that most human medicines are now dispensed in their original packaging with the accompanying authorised package leaflet, instead of being bought in bulk and then repackaged. If repackaged, a patient information leaflet must be provided. Patient information leaflets for most authorised human medicines can be printed from the electronic Medicines Compendium website

Patient information leaflets are based on the authorised SPC and there are strict criteria on how the information is presented (MHRA 2014). Each leaflet must be tested with target patient groups to ensure that it is legible and clear, and medical terms are translated into language that most patients can understand (MHRA 2014). There are guidelines on type size and font, design and layout, and headings to help navigate the text (MHRA 2014). A well-designed and clearly-worded package leaflet maximises the number of people who can use the information including those with poor literacy skills or sight loss. 

By law anyone prescribing or supplying veterinary medicines must be satisfied that the person who will use the product is competent to use it safely and intends to use it as authorised. The prescriber or supplier must also advise on the medicine’s safe administration, and any warnings or contraindications (Veterinary Medicines Regulations 2013). There is no legal requirement to label medicines supplied in their authorised packing; however the RCVS considers it good practice for all prescription medicines to have a dispensing label attached containing the following information (BSAVA 2017): 

  • Name and address of the animal owner

  • Name and address of the veterinary practice supplying the medicine

  • Date of supply

  • Name, strength and quantity of product

  • Dosage and directions for use

  • The words ‘For animal treatment only’

  • For topical preparations ‘For external use only’.

A vet or pharmacist supplying a product against a written prescription may amend the authorised package label to reflect the prescription (e.g. to change the dose), although none of the other information on the outer packaging or the immediate container must be obscured (VMD 2017b).

If a medicine is supplied in a container other than its original packaging (e.g. tablets dispensed in smaller containers) the person supplying the product must give sufficient written information for the medicine to be used safely (BSAVA 2016, Veterinary Medicines Regulations 2013). For example, if parasiticide products are split for supplying or administering single doses in the practice (e.g. at puppy parties), pet owners must be given a copy of the package leaflet. In reality, it can be difficult to get spare copies of package leaflets for licensed veterinary medicines because they are not readily available online. Many practices photocopy the leaflets that come with large boxes of tablets that will be split up, if not enough leaflets have been supplied in the original pack. An alternative is to print the SPC or NOAH data sheet, although these will not contain the specific wording directed at pet owners that is included in package leaflets (see above). 

Vets must ensure that any person handing out the medicine is competent to do so (VMD 2013) but there is no legal requirement for staff that dispense medicines to have formal training (BSAVA 2016). 

Online retailers that sell veterinary medicines must ensure that a suitably qualified person (SQP) has assessed the details provided by the customer and advised them on how to use the medicine safely. The VMD runs a voluntary ‘Accredited Internet Retailer Scheme’ (AIRS) for UK websites selling veterinary medicines. This aims to reduce the risk of people buying unauthorised, inappropriate or ineffective veterinary medicines. Accredited websites can display a logo to indicate that the VMD has assessed how veterinary medicines are sold on that site and that it complies with the AIRS requirements and the Veterinary Medicines Regulations. 

If an unlicensed medicine is supplied under the prescribing ‘cascade’, it is a legal requirement to supply the following information (VMD 2015, Veterinary Medicines Regulations 2013): 

  • Name and address of the veterinary practice supplying the product

  • Name (or initials) of the veterinary surgeon who prescribed it

  • Name and address of the animal owner

  • Identification (including the species) of the animal or group of animals

  • Date of supply

  • Expiry date of the product, if applicable

  • Name or description of the product (at least the name and quantity of active ingredients)

  • Dosage and administration instructions

  • Any special storage precautions

  • Any necessary warnings for the user, target species, administration or disposal of the product

  • Withdrawal period, if relevant

  • The words 'Keep out of reach of children’ and ‘For animal treatment only’.

The product must be labelled with this information (Veterinary Medicines Regulations 2013) but it is reasonable to place some of the required information on a separate sheet [personal communication, VMD]. 

Companies that market specials do not provide package leaflets with their products.

The BSAVA publishes client information leaflets on commonly-prescribed unlicensed medicines (currently 61 individual drugs and three drug groups: antibacterials, topical eye treatments, steroids). These are well laid out and written in a style suitable for lay people. Plumb’s Veterinary Medicines monographs include helpful bulleted information to tell clients. EBVM.vet/Vetformulary and Vetstream Vetlexicon are other sources of information for clients on unlicensed medicines. There may be instances when practices need to consider creating their own information if ready-made leaflets are not available, but this requires time and skill to get right. Many Veterinary Prescriber modules include a section on what to say to clients. 

  • People will have a better understanding if they are given both written and verbal instructions on how to use medicines.

  • Remind owners to read the label and leaflet. Encourage them to ask questions during the consultation or to contact the practice at any stage if they need to.

  • Become familiar with the available written information and do not assume that an owner will read it, understand it all, or that the information will be specific to every patient (e.g. the leaflet of an authorised medicine will not mention an unauthorised use).

  • The law requires that owners are given information on the safe and effective use of cascade medicines.

  • If parasiticide products are split for supplying or administering single doses in the practice (e.g. at puppy parties), give pet owners a copy of the package leaflet.

  • Ensure that dispensing staff know where to find information on medicines and when it should be given out.

Owners need clear, easy-to-understand information to be able to use medicines effectively and safely. The law goes some way to ensure that minimum information requirements are met when medicines are dispensed. However, package leaflets included with authorised veterinary medicines often use difficult technical language, provide too much information, and do not present important instructions for use prominently. 

Veterinary medicines regulators and pharmaceutical companies must do more to ensure that all package leaflets are clear and easy for pet owners to understand. Package leaflets should be readily accessible online for all authorised veterinary medicines. 

Practices must ensure that all medicines are dispensed with clear written information for owners to refer to at home, including medicines prescribed under the cascade and items not provided in their original packaging. Vets should be aware of what information, if any, is provided with a medicine, and its shortcomings. Anyone dispensing medicines must be adequately trained and have sufficient knowledge to be able to advise owners about medicines and where to find more information if necessary.


If you prefer, you can listen to the whole audio presentation of this module using the following podcast. Don't forget that you can also download the podcast to your iPod, music player, tablet or smartphone using the Download link on the right of the audio player.


Click the play button below to answer the multiple choice questions on this module. Start by entering your first and second names and your email address so we can send you a CPD certificate for your records. 

How we produced this module

Our modules start with a detailed outline and electronic literature search. We commission a collaborating author, who is a specialist in the module topic, to write a draft module. The collaborating author on this module was Emily Newsom-Davis. The draft is circulated unsigned to a wide range of commentators, include practising first-opinion vets, other topic specialists, the companies that market any mentioned drugs and other organisations and individuals, as appropriate. They can raise points about the interpretation of evidence, ask questions that are important to clinical practice, and present alternative viewpoints. There is a rigorous editing and checking process and the result is a module that is evidence-based, impartial and relevant to clinical practice. The final module is unsigned because it is the result of collaboration. 


Amery WK. Coming full circle in pharmacovigilance: communicating safety information to patients through patient package inserts. Pharmacoepidemiol Drug Saf 1999; 8: 121–9.

Aronson JK. Editor’s view. Compliance, concordance, adherence. Br J Clin Pharm 2007; 63: 383-4.

Atkins CE et al. Heartworm ‘lack of effectiveness’ claims in the Mississippi delta: computerized analysis of owner compliance – 2004–2011. Vet Parasitol 2014; 206: 106–113.

Barter LS et al. Comparison of methods to assess dog owners’ compliance. Aust Vet J 1996; 74: 443–6.

BSAVA. Guide to the use of veterinary medicines, 2nd edition. Gloucester: British Small Animal Veterinary Association, 2016. 

Coles TB, Dryden MW. Insecticide/acaricide resistance in fleas and ticks infesting dogs and cats. Parasites Vectors 2014; 7: 8.

Patient pack prescribing and the provision of patient information leaflets. DTB 1995; 33: 86–8.

Elsheikha H. Companion animal worming – maximising owner compliance. Vet Times 2016: 46.30.

European Medicines Agency. Product-information requirements [online] [Accessed 20 November 2017].

Iuga AO, McGuire MJ. Adherence and healthcare costs. Risk Manag Health Policy 2014; 7: 34-44.

U.S. Food & Drug Administration. Medications for Your Pet ... Questions for Your Vet [online]. [Accessed 11 December 2017].

Jin J et al. Factors affecting therapeutic compliance: a review from the patient’s perspective. Ther Clin Risk Manag 2008; 4: 269–86.

Johnson A et al. Written and verbal information versus verbal information only for patients being discharged from acute hospital settings to home. Cochrane Database of Systematic Reviews 2003, Issue 4.

Matos M et al. Parasite control practices and public perception of parasitic diseases: a survey of dog and cat owners. Prevent Vet Med 2015; 122: 174-80.

MHRA. Best practice guidance on patient information leaflets. London: Medicines and Healthcare products Regulatory Agency, 2014 [online].[Accessed 20 November 2017].

Murphy SA. Consumer health information for pet owners. J Med Libr Assoc 2006; 94: 152–8.

National Institute for Health and Care Excellence. Medicines adherence: involving patients in decisions about prescribed medicines and supporting adherence, 2009 [online].[Accessed 20 November 2017].

Veterinary Medicines Directorate. The Cascade: Prescribing unauthorised medicines, 2015 (online). [Accessed 20 November 2017].

The Veterinary Medicines Regulations 2013 No. 2033, [Statutory Instruments]. 

VMD 2016b. Veterinary Medicines Directorate. Product Literature Standards (PLS) for veterinary medicinal products, 2016 (online). 

VMD 2016a. Veterinary Medicines Directorate. Veterinary Pharmacovigilance in the United Kingdom. Annual Review, 2014. 2016 (online). 

VMD 2017a. Veterinary Medicines Directorate. Veterinary Pharmacovigilance in the United Kingdom. Annual Review, 2015. 2017 (online). 

VMD 2017b Veterinary Medicines Directorate. Retail of veterinary medicines, 2017 (online). [Accessed 11 December 2017].