It’s not always easy to tell if a drug you prescribe for a patient is legally marketed for animals, meaning if it’s approved, conditionally approved, or indexed. You can’t tell by looking at the tablet in your hand or the solution in the bottle. You can’t tell by feeling or smelling the drug. But, here are some tips to help you identify a legally marketed animal drug:

Look at the drug’s label.

All FDA-approved animal drugs have a New Animal Drug Application (NADA) number, or for generic animal drugs, an Abbreviated New Animal Drug Application (ANADA) number. Many drug manufacturers currently list the six-digit NADA or ANADA number and the statement, “Approved by FDA,” on the drug’s label. By the end of September 2023, all drug manufacturers will be required to list this information on the label of every approved animal drug.

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The same approved animal drug can be legally marketed under several labels. These different labels are made by the various companies that distribute the drug. Each distributor can use a different proprietary name (also known as trade name or brand name) for the drug.

For example, the drug company Vetoquinol has an approved Abbreviated New Animal Drug Application (ANADA) for phenylbutazone paste for horses. Under this same approved application (ANADA number 200-266), four distributors market the paste, each with a different proprietary name:

This can get confusing, so it’s important to look at the drug’s label. If you order one of the above phenylbutazone paste products and see “ANADA 200-266” on the label, you can be confident the drug is FDA-approved for horses.

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Animal drugs conditionally approved by FDA also have a six-digit application number which appears on the drug’s label as part of the following required statement:

“Conditionally approved by FDA pending a full demonstration of effectiveness under application number XXX-XXX.”

Indexed animal drugs have a Minor species Index File (MIF) number. The six-digit MIF number appears on the drug’s label as part of the following required statements:

“LEGAL STATUS—In order to be legally marketed, a new animal drug intended for a minor species must be Approved, Conditionally Approved, or Indexed by the Food and Drug Administration. THIS PRODUCT IS INDEXED—MIF XXX-XXX. Extra-label use is prohibited.”

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Check FDA's website.

If you’ve looked at the drug’s label and can’t find an application or MIF number, then you can check a couple of places on FDA’s website to see if the drug is legally marketed for animals:

Look up the drug in Animal Drugs @ FDA. Most FDA-approved and conditionally approved animal drugs are listed in Animal Drugs @ FDA, a searchable online database. The database allows you to search using several parameters, including proprietary name (also known as trade name or brand name), ingredient, and application (NADA or ANADA) number. Indexed animal drugs are not listed in Animal Drugs @ FDA.

Look up the drug in the Green Book. Most FDA-approved animal drugs are included in the online publication, Approved Animal Drug Products, called the Green Book, for short. FDA updates the Green Book Reports monthly and you can find these reports on Animal Drugs @ FDA. While the information in the Green Book is mainly used by companies wanting to manufacture and distribute generic animal drugs, it is also a resource for the public. Conditionally approved and indexed animal drugs are not listed in the Green Book.

The Green Book is divided into seven sections. To find out if a drug is FDA-approved for animals, the first two sections are the most helpful:

• Section 1 is divided into two subsections. Section 1.1 lists approved animal drugs alphabetically by trade name. Section 1.2 lists approved animal drugs by application number, from lowest to highest.
• Section 2 lists approved animal drugs alphabetically by active ingredient.

In the Green Book, the header "Application Number" refers to either a New Animal Drug Application (NADA) number for a brand name animal drug, or an Abbreviated New Animal Drug Application (ANADA) number for a generic animal drug. If the number in this column is less than 200-000, the animal drug is a brand name drug with an approved NADA. A number over 200-000 indicates the animal drug is a generic drug with an approved ANADA.

Look up the drug in FDA’s Index of Legally Marketed Unapproved New Animal Drugs for Minor Species.

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Common Misconceptions

Misconception: An animal drug is legally marketed if the label includes an NDC number.

Truth: The presence of a National Drug Code (NDC) number on an animal drug’s label does not mean the drug is legally marketed. Under federal law, all drug manufacturers must register with FDA and give the agency a list of their marketed drugs. This requirement for drug manufacturers to “register and drug list” with FDA applies to all marketed drugs, including unapproved ones.

FDA assigns a unique three-segment NDC number to each registered drug, regardless of whether it’s legally marketed or not, to indicate the drug is in commercial distribution. Many drug manufacturers include the NDC number on the drug’s label. FDA publishes the NDC numbers of registered human drugs in the National Drug Code Directory. There is no NDC directory for registered animal drugs.

Misconception: An animal drug is legally marketed if the label includes the statement, “Caution: Federal law restricts this drug to use by or on the order of a licensed veterinarian.”

Truth: The presence of the caution statement on the label does not mean it’s a legally marketed prescription animal drug. Federal law requires that the caution statement be included on the label if the animal drug can only be safely used under a licensed veterinarian’s supervision. Again, this legal requirement applies to all marketed drugs, including unapproved ones.

The labels of some marketed animal drugs have other statements that you should also not take to mean the drugs are legally marketed, such as:

• “Registered and listed with the FDA”
• “Made in an FDA-registered facility”
• “Made in an FDA-inspected facility”
• “Made in an FDA-approved facility”

Bottom line: If you see an NDC number, the caution statement, or any of the above statements on the label, don’t assume the drug is legally marketed. You have to look a bit harder to tell if the drug is legally marketed for animals or FDA-approved for people.