Protecting Swine Health through Validated-Qualified Herds

The United States Department of Agriculture’s Animal and Plant Health Inspection 

Service (USDA APHIS) is responsible for protecting American agriculture and natural 

resources. As part of this goal, APHIS protects the health of the nation’s livestock herds 

and poultry flocks. We work to keep foreign diseases out of the country and to keep 

diseases that are present in the United States under control.

Two domestic diseases of concern in swine are swine brucellosis and pseudorabies. 

Swine brucellosis causes abortion, infertility and small litter sizes. Pseudorabies causes 

death in newborn piglets. These diseases can have a significant impact on herd 

productivity. Through a cooperative effort, animal health officials and the swine industry 

eliminated them from indoor swine herds – swine brucellosis in 2011 and pseudorabies in 

2004.

However, both diseases can still be found in feral (wild) pigs. If animals from 

indoor/outdoor swine herds have contact with feral pigs during outdoor periods, the herd 

can become infected. And if one infected pig joins a new herd, that herd can also become 

infected. To address this concern, APHIS established the Validated Brucellosis-free and 

Qualified Pseudorabies negative herd programs. Producers can choose to participate in 

one or both programs.

Validated-Qualified Herds

Validated-Qualified (VQ) swine herds provide assurance that their animals are free of 

these diseases. To gain VQ status, producers must test a certain amount of their herd for 

these diseases every year within a specific timeframe. All animals must test negative. 

They must also follow guidelines to prevent diseases from entering the herd when 

purchasing new additions. The specific guidelines for which pigs, how many, and when 

to test are found in USDA’s Uniform Methods and Rules for each disease. This status 

must be renewed annually.

Buying from a VQ Herd

When adding to your herd, consider buying animals from VQ herds. This simple step 

greatly reduces the risk of introducing swine brucellosis or pseudorabies into your herd. 

Because of the strict testing regiment and biosecurity practices required to gain and keep 

VQ herd status, you can feel confident in your new additions. Also, they will not 

threaten the health of your family and other animals.

Testing an individual animal from a non-VQ herd before buying it is not as effective as 

purchasing from a VQ herd. There are several reasons why. First, the accuracy of the 

test depends on the length of infection, the immune response, reactions to other disease 

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agents and the type of test used. Second, the tests are much better at identifying an 

infected herd (many tests being run on the herd) than detecting just one infected animal. 

It is possible that an animal could test negative even though the herd, and even the animal 

itself, is infected. 

Herds which test negative over time are more likely to be truly disease free. Owners of 

VQ herds also use consistent biosecurity practices to keep the disease from being 

introduced. 

To verify VQ status, look for a document from the state department of agriculture 

showing the herd is VQ and the last test date. This date should be within the past 12 

months. If you have any questions, contact state animal health officials or APHIS.

Benefits of Having a VQ Herd

Earning VQ status is helpful for herds that sell, trade or share feeder pigs, show pigs or 

breeding pigs. Buyers look to VQ herds to help ensure their new animals are disease-free.

Any herd with breeding animals can use VQ status to help protect herd health. Because 

these diseases can affect more than just swine, the programs also help protect the health 

of other livestock, pets (dogs/cats) and even people. Pseudorabies can infect cattle, sheep 

and other animals, and is usually fatal in animals other than swine. Pseudorabies does 

not affect people. On the other hand, brucellosis can affect both people and other animals. 

People are most like to get brucellosis by assisting an infected sow with farrowing, 

slaughtering infected pigs and field dressing infected feral hogs. When properly treated, 

brucellosis is not usually fatal to humans but can cause serious chronic health problems.

Becoming a VQ Herd

If you wish to become a VQ herd, start by contacting your herd veterinarian or the State 

Veterinarian. Depending on the state, you may need to complete an application form or 

simply put VQ on your laboratory submission forms as the reason for testing. Your 

veterinarian, or potentially animal health officials (in areas with few swine veterinarians), 

will collect blood samples from your animals for testing.

For both statuses, you will need to test all breeding swine over 6 months of age. In 

addition, you will need to test some 4-6 month old pigs that were born on the farm to gain 

qualified pseudorabies negative status. You must test an amount equal to 20% of the 

breeding swine (for example, 10 pigs born on the farm for a herd with 50 breeding pigs). 

All tests must be negative to gain VQ status. 

There are three ways to reach the required testing numbers. You may:

• Test annually - all animals once a year;

• Test quarterly - 25% of breeding swine over 6 months of age and the number of 4-

6 month offspring equal to 6% of the breeding herd each every 85-105 days; or

• Test monthly 10% of breeding swine over 6 months of age and the number of 4-6 

month offspring equal to 3% of the breeding herd every 25-35 days.
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No individual animal can be tested twice in 10 months to meet the testing numbers. The 

herd cannot gain VQ status until all its breeding swine, and the required number of 

offspring test negative. 

Keeping VQ Status

VQ status is good for one year – that’s the anniversary date. If all pigs were tested on the 

same date, the anniversary date is the day the blood was drawn. To maintain VQ status, a 

whole herd test can be done once a year, prior to the anniversary date. There is no grace 

period – the VQ status expires one year after the anniversary date.

Once VQ status is achieved, you can maintain it by testing monthly or quarterly (at the 

same rate as to obtain VQ status over time). Testing every quarter or month helps ensure 

the herd’s status won’t expire. 

To keep VQ status when adding outside animals to the herd, you must purchase animals 

from other current VQ herds. Movements of swine from one VQ herd to another VQ 

herd do not require additional testing. Only use semen from boars in VQ herds for 

artificial insemination.

To move breeding swine from a non-VQ herd, you must:

• Test the new pig for Brucellosis and PRV in the herd of origin 30 days prior to 

movement; 

• Retest the new pig for Brucellosis and PRV 30-60 days after arrival; and 

• Keep the new pig isolated from your herd until you get negative results for the second 

test.

For More Information

For more details on the requirements of becoming and remaining a VQ herd, go to: 

https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/animal-diseaseinformation/swine-disease-information/ct_swine_health_home

For Pseudorabies click on the link for Program Standards. When the Program Standards 

open, go to the section on PRV-free Qualified Herd. For Swine Brucellosis, click on the 

link for Uniform Method and Rules (UM&R). When the UM&R opens, go to the section 

on Validated Brucellosis-free herd.

For information on becoming a VQ herd, contact your local APHIS Veterinary Services 

office or your State Veterinarian.