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Veterinary Medication Errors

The FDA Center for Veterinary Medicine (CVM) works to prevent veterinary drug medication errors. A medication error, as defined by the National Coordinating Council for Medication Error Reporting and Prevention, is "any preventable event that may cause or lead to inappropriate medication use or patient harm while the medication is in the control of the health care professional, patient, or consumer. Such events may be related to professional practice, health care products, procedures, and systems, including: prescribing; order communication; product labeling, packaging and nomenclature; compounding; dispensing; distribution; administration; education; monitoring; and use."

What would you like to Learn About?

Veterinary Medication Error Causes and Public Health Consequences
CVM’s Role in Preventing Medication Errors
Case Examples of Veterinary Medication Errors
For Consumers: Suggestions for How to Avoid Medication Errors and Medication Accidental Exposures for Your Animals
How to Report Veterinary Medication Errors
For Industry
View Other Resources

Veterinary Medication Error Causes and Public Health Consequences

CVM is responsible for monitoring and addressing issues that affect both animal and human health, including veterinary medication errors. When drug label information is misinterpreted or when one drug is mistaken for another, the treated animal’s health may be harmed. Medication errors involving animal drugs can also affect human health. For example, medication errors involving drugs used in food-producing animals could cause unsafe drug residues in human food. Also, there is a potential risk to people handling animal drugs if the drugs are handled or used improperly.

Some causes of medication errors include, but are not limited to:

  • drug names that look alike or sound alike
  • drug labels that are presented in certain ways, such as lack of background color contrast, overcrowded information, inconsistent presentation of drug strength, and use of certain font style and size 
  • drug dosage devices (such as oral syringes) that are difficult to use because of poor design or inadequate directions for use 
  • use of error-prone abbreviations or symbols on written prescriptions
  • illegible handwriting on written prescriptions
  • miscommunication while verbally prescribing orders
  • some product defects (e.g., faulty parts or packaging, incorrect or missing label information) that could result in accidental exposures and potential harm to the patient
  • improper storage or disposal of drug products that could lead to accidental exposures and/or overdoses

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CVM’s Role in Preventing Medication Errors

Within CVM’s Office of New Animal Drug Evaluation (ONADE), primary review divisions prospectively evaluate drug names, labeling, packaging, and product design prior to drug approval to help prevent medication errors. ONADE may also consult with CVM’s Office of Surveillance and Compliance in evaluating these aspects of the drug product. After a drug is approved and marketed, review divisions within CVM’s Office of Surveillance and Compliance monitor the post approval experience with the drug and overall safety profile, including review of adverse drug experience (ADE) reports, some of which may describe a medication error as a possible contributing factor to the ADE. Evaluation of these reports may lead to label/package design improvements and/or re-assessment of the drug name and other potential sources of error associated with the drug. In addition, CVM provides outreach about preventable veterinary medication errors to the public and veterinary professionals through various publications and presentations. Here are some of the things that CVM does to help prevent medication errors: 

  • Evaluation of Drug Names - A drug name is a critical “identifier” of every drug. Drug name confusion or misinterpretation of the drug name could lead to a medication error causing patient harm. For example, misinterpreting the drug name may cause the wrong drug to be given to the patient. When reviewing proposed drug names, CVM considers potential safety issues, such as look-alike or sound-alike names, that may result in name confusion and medication errors.
  • Review of Drug Labels and Packaging Design - The drug label is the primary way veterinarians and animal owners interact with a drug. The label communicates critical information about the drug, including:
    • proprietary (sometimes called Trade or Brand name) and established names,
      • Example: Amoxi-Tabs (amoxicillin). “Amoxi-Tabs” is the drug’s proprietary name and “amoxicillin” is its established name.
    • drug strength,
    • dosage form,
    • route of administration,
    • container quantity,
    • lot number, and
    • expiration date.

      Before approval of an animal drug, CVM evaluates the drug’s labeling; from its container and carton labels, to its package insert and dosing device. We strive to identify potential problem areas, such as how the label displays and presents drug information. We may also assess the drug’s package design for user-friendliness, including instructions for use that are easily understood.
       
  • Review of Adverse Drug Event Reports and other sources of information - After CVM approves a drug, we continue evaluating it by reviewing available sources of information related to the post approval performance of the product including adverse drug event (ADE) reports. Some of these reports may describe medication errors as possible contributing factors to the ADEs. Based on our findings, we may ask the drug company to improve the drug’s package or label design, reassess the drug’s name, or take other actions intended to minimize potential for medication error.
  • Educational Outreach - CVM aims to increase awareness about veterinary medication errors and to educate veterinary professionals and the public about this important issue. Our outreach includes publications and presentations to the animal health industry, veterinary professional organizations, practicing veterinarians, veterinary colleges, veterinary technicians, and human healthcare practitioners including pharmacists, pharmacy technicians, and others as needed.

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Case Examples of Medication Errors

The following examples are taken from FDA case reports. The examples involve actual medication errors or situations where medication errors could have occurred. The first example describes a medication error involving human drugs; the other examples involve veterinary drugs.

Examples Involving Drug Names

In veterinary medicine, both animal drugs and human drugs can be used to treat animals.  Human drugs are commonly used to treat animals (under certain conditions, it is legal to use FDA-approved human drugs to treat animals in an extralabel manner - see Animal Medicinal Drug Use Clarification Act of 1994 (AMDUCA)).

Commonly, some veterinary clinics carry both animal and human drugs. Veterinary prescriptions for a human drug could also be filled and dispensed at a human pharmacy.  While the use of human drugs opens up therapeutic options, it can also increase opportunities for a drug name mix-up to occur (see Figure 1).  In the veterinary medication use process, there are several different ways drug name mix-up errors can occur.  As demonstrated in Figure 1, there may be confusion between two animal drug names, confusion between two human drug names, and/or confusion between an animal drug and human drug name.  Any of these scenarios could result in a medication error as described in case examples 1, 2, and 3.

In the veterinary medication use process, there are several different ways drug name mix-up errors can occur.  As demonstrated in Figure 1, there may be confusion between two animal drug names, confusion between two human drug names, and/or confusion between an animal drug and human drug name.  Any of these scenarios could result in a medication error, as described in case examples 1, 2, and 3.

Figure 1:  Different ways drug name errors occur in veterinary medicine

Case 1: Animal drug name confusion and error

This case example involved a transcription error involving a prescription at a veterinary hospital pharmacy. The veterinary pharmacist noted that the two brand name drugs, “Convenia” and “Cerenia,” can look-alike on written orders. Convenia is for the treatment of skin infections in dogs and cats and Cerenia is for the prevention and/or treatment of vomiting in dogs and cats. Both are injectable drugs that are dosed by the patient’s body weight. The error resulted in mislabeling of the prescription label with the wrong drug name and billing for the wrong drug. However, the veterinary pharmacist caught the error prior to dispensing the drug product and the wrong drug was not dispensed or administered to the dog. The reporter noted that the look-alike names and overlapping characteristics about the products (e.g., both are used in cats or dogs, both are injectable drugs that can have the same or similar amount administered) may increase the risk of confusion.

Case 2: Human drug name confusion and error

Hydroxyzine and hydralazine are approved human drugs.  Hydroxyzine is an antihistamine used to relieve itching caused by allergic skin reactions. Hydralazine is used to treat high blood pressure.  This name pair is well recognized in human medicine to cause confusion and errors due to look-alike and sound-alike similarities between the two names.  Human drugs are commonly used to treat animals (under certain conditions, it is legal to use FDA-approved human drugs to treat animals in an extralabel manner).  As such, human drugs known to cause drug name errors in the human medication use process can also cause errors in the veterinary medication use process.  In one case, the veterinarian prescribed hydroxyzine for the dog.  The pet owner administered the medicine for two days before noticing the drug information sheet indicated the medicine was for treatment of high blood pressure. The consumer called the pharmacist who confirmed a mix-up did occur. The dog was actually dispensed hydralazine instead of the prescribed hydroxyzine.

Case 3: Animal drug name and human drug name confusion and error

This example illustrates the potential for animal injury due to confusion between human drugs and animal drugs that have sound-alike or look-alike names. CVM received a report of a dog mistakenly receiving the human drug Sinequan (doxepin) instead of the prescribed animal drug Zeniquin (marbofloxacin). Sinequan (doxepin) is used to treat depression and anxiety in humans.  Zeniquin (marbofloxacin) is an antibiotic approved for use in cats and dogs.  The dog became ill (lethargy, anorexia, and not urinating) 24 hours after being administered the Sinequan. The dog was treated and recovered. In this case, possible contributing factors may have included: The sound-alike similarity between the animal drug name (Zeniquin) and the human drug name (Sinequan). The brand name human drug Sinequan (doxepin) is a discontinued drug product; however, Sinequan still has strong brand name recognition and reference to the brand name Sinequan is found in human drug references and animal drug references. Generic doxepin may be prescribed by veterinarians for legal extralabel use to treat animals for various conditions. Some pharmacies may not be familiar with certain animal drugs, especially brand names. Additionally, although this case involved a prescription communicated orally, we note that the name pair also has look-alike similarities when health care professionals are scripting and/or when pharmacists are dispensing medications for animals. For more information, please see FDA Advise-ERR: Veterinary Drug and Human Drug – A Drug Name Mix-up.

Examples involving errors due to use of error-prone notations

Case 1: 

A veterinarian injected an animal patient with 5 mL of an antibiotic.  The next day, the veterinarian realized that the patient she had treated had received a 10-fold overdose of an antibiotic with known toxic side effects to the kidneys.  She had misread a poorly placed decimal point. 

When a decimal point is not prominently placed, either using a trailing zero after the decimal point or not using a leading zero before a decimal point can lead to misinterpretation of the dose and cause an error in dosing, in this case a ten-fold overdose. For example,

  • If a trailing zero is used, what is written as “5.0 mg” (five mg) may be misread as “50 mg” (fifty mg)
  • If a leading zero is not used, what is written as “.5 mg” (zero point five or ½ mg) may be misread as “5 mg” (five mg)

In general, use of a trailing zero should be avoided, while leading zeroes can help by making the decimal point location clearer. 

Case 2:  

At a veterinary clinic, Baytril tablets “SID” were prescribed for a cat.  Baytril (enrofloxacin) is an antibiotic for cats and dogs.  SID is a medical notation sometimes used to denote once a day dosing.  However, the order was wrongly transcribed and labeled “QID” and resulted in an overdose.  QID is a medical notation for four times a day dosing (i.e., every 6 hours). In this case, there was an overdose due to similarities with SID and QID when scripted.  For a drug where there is a strong correlation between the dose and the severity of side effects, an overdose can have serious consequences. 

Medication errors can occur because abbreviations or symbols can be misinterpreted.  Abbreviations and symbols can be vague and unfamiliar, causing the intended meaning to be improperly conveyed.  Medication errors in animals occur not only in veterinary clinics, but also in pharmacies where pharmacists and pharmacy technicians may be unfamiliar with veterinary abbreviations.

Examples of errors involving labels/labeling and packaging configuration

Sometimes, the drug labels or packaging configuration can be confusing or misleading which can lead to medication errors.  The following examples are from reports received by CVM and involve potential or actual errors related to animal drug labels and packaging design.

  • CVM has received many reports involving accidental overdose with Sileo in dogs treated with the drug.  Sileo (dexmedetomidine) oromucosal gel is a prescription gel that is given to dogs by mouth to treat noise aversion (signs related to anxiety or fear due to noise). It was designed to be administered using an oral dosing syringe which would deliver a certain pre-measured dose. Reported use errors that resulted in accidental overdoses involved operation of the dosing syringe’s ring-stop. CVM received reports of users following the instructions, but the dosing syringe failed to operate as it was intended, and it was difficult to use. To mitigate the potential for further use error, the FDA and the manufacturer implemented enhanced labeling, training videos, and communication with veterinarians to teach and show the handlers of the product how to properly handle and administer Sileo to dogs.  Additionally, CVM Updates were published to inform veterinary practitioners and animal owners about the issue: See FDA Animal Drug Safety Communication: FDA continues to warn about risk of accidental overdosing of dogs with the noise aversion drug Sileo
  • An injectable antibiotic drug for food-producing animals has silver writing on a white container label. It was reported that it was “…difficult to read the drug information outside or in the barn when treating the animals….”
  • An antibiotic labeled for intramammary infusion in dry (non-lactating) dairy cows was mistakenly given to lactating dairy cows. The milk from the treated cows tested positive for antibiotic residues. The report stated, “…the drug container label for the lactating dairy cow is too similar to the drug for dry dairy cattle, so can get easily confused....”
  • A veterinarian reported that he almost gave the wrong drug to his client for administration to his cattle. The veterinarian confused a drug used to cause luteolysis in beef and dairy cattle with a drug used to prevent and treat selenium-Vitamin E deficiency in weanling calves and breeding beef cattle. He stated the drugs’ packaging looked too similar.

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For Consumers: Suggestions for How to Avoid Medication Errors and Accidental Medication Exposures for Your Animals

Most medication errors are preventable. Communication is one of the keys to preventing medication errors. It's not much different from what you would do for you or for your child when your doctor prescribes a drug product. If you don’t understand why your veterinarian is ordering or prescribing a drug for your animal, ask. Other questions you can ask your veterinarian are:

  • What is the name of the drug? What is it supposed to do?
  • Could it interact with other drugs my animal is currently taking?
  • What are the possible side effects and what should I do to care for my animal?
  • How do I give it? Do liquids have to be shaken before use?
  • How many times a day should I give it?
  • How much do I give each time?
  • Should I give it before, during, or after meals?
  • What if I accidentally give too much?
  • What should I do if I forget to give a dose to my animal?
  • What should I do if my animal vomits or spits it out?
  • How should I store it and how do I dispose of any unused medication?
  • Should I finish giving all the medication, even if my animal seems better?

Asking questions is important, but sometimes it’s not enough. Share information about your pet with your veterinarian, especially if you are getting a new prescription or visiting that veterinarian for the first time. Here are some suggestions that might help.

  • Keep a list of drugs that your animal is taking – including over-the-counter drugs, supplements, and prescription drugs. Bring it with you and show it to your veterinarian.
  • Discuss any drugs that your animal is allergic to or that have caused problems in the past.
  • Discuss any serious or chronic health conditions that your animal may have.

Here are some steps that could help you avoid medication errors and accidental medication exposures at home:

  • Read labels and follow directions.
  • Do not cut, crush, or break capsules or tablets unless your veterinarian tells you to do so. If your veterinarian tells you to cut the tablet in half, use a pill cutter (available at most drugstores) to get the most accurate dose possible.
  • Keep your animal’s drugs in their original labeled containers.  
  • Do not share one animal’s drug with another unless your veterinarian says it's OK to do so.
  • Store animal drugs away from human drugs to prevent mix-ups and accidental human exposure to animal drugs and animals to human medications.
  • Store animal drugs out of reach of household pets. This is especially true of flavored chewable tablets which may lead to the pet seeking and consuming the flavored tablets, which may result in potentially serious accidental overdoses.
  • Store animal drugs up out of reach of children.
  • Store any human medications you may have at home out of reach of your pets to prevent accidental exposures and overdoses.

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Report Veterinary Medication Errors

We encourage you to report all medication errors, including those that are not associated with an adverse event.  This allows us to monitor and be proactive in preventing adverse events that may result from medication errors.

  • A medication error may cause a serious adverse event for the treated animal patient. If a veterinary professional or an animal owner reports a serious adverse event to the drug company, the drug company is obligated to comply with the regulations in 21 CFR 514.80 (b)(2) for reporting of all serious, unexpected adverse experiences to CVM.
  • In other cases, a medication error may not harm the patient. Perhaps someone caught the medication error before the drug was dispensed or given to a patient. Maybe a veterinarian or an animal owner recognized the potential for label or name confusion. Although drug manufactures are not required to send medication error reports that did not result in an adverse event to CVM, voluntary reporting of these events to CVM by veterinarians, veterinary technicians/nurses, pharmacists, pharmacy technicians, and animal owners is encouraged, regardless of the patient outcome. 

Voluntary reports can be submitted to the FDA using FORM FDA 1932a, "Veterinary Adverse Experience, Lack of Effectiveness or Product Defect Report". You can use this form to report medication errors with or without adverse events for any animal drug (approved or not approved by FDA) or animal device. Unapproved animal drugs include compounded drug products.

  • Download/open the fillable 1932a electronic form 
  • Open the file, complete the fillable form, and email the completed form to CVM1932a@fda.hhs.gov.

More Information on How to Report an Adverse Event to CVM

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For Industry

CVM has a list of additional terms used internally to describe product problems; as such terms do not exist in VeDDRA. Examples include problems related to manufacturing and shipping, as well as terms used to describe medication errors. These terms are now available for use in Adverse Event Report (AER) submission to CVM, should you choose to use them.

Please see ‘Veterinary Adverse Event Reporting for Manufacturers’ for information concerning the voluntary use of CVM’s internal medication error terms. Specifically, please refer to the following documents under the Supporting Document section: ‘CVM GFI #188 Guidance for Data Elements for Submission of Veterinary Adverse Event Reports to the Center for Veterinary Medicine’ (PDF); and ‘CVM Internal Terms for Use in Veterinary ADE Reporting’ (Excel).

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Other Resources

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