Starting today, Monday, April 29, new restrictions are in place for the movement of lactating dairy cattle across state lines. This decision is an attempt to limit the further spread of highly pathogenic H5N1 avian influenza that has been identified in dairy cows in a growing number of states.

Last week, USDA issued a federal order that requires lactating dairy cattle be tested for the virus prior to interstate movement; this includes animals being transported for slaughter. A negative test within seven days of transport will be required before a Certificate of Veterinary Inspection can be issued. Testing is recommended for dry cows and heifers but is not required at this time.

USDA will cover the cost of these pre-movement tests, which must be submitted to an approved National Animal Health Laboratory Network laboratory. Results will be available within two or three days, according to USDA. In addition, the federal order now requires all laboratories and state veterinarians to report H5N1 cases to USDA.

If an animal tests positive during the pre-movement testing, it should be quarantined for 30 days before retesting. Herd owners with positive animals must provide epidemiological information, including animal movement tracing.

Since H5N1 was first confirmed on a Texas dairy in late March, USDA, veterinarians, and others have been racing to learn more about the virus and its transmission. Spread between cows in the same herd has been confirmed, along with spread between dairies because of cattle movement and transmission from cows to poultry. Cows without clinical signs have also tested positive.

As of last week, USDA confirmed the virus was detected on 33 farms in eight states, including Idaho, Kansas, Michigan, New Mexico, North Carolina, Ohio, South Dakota, and Texas. A number of states had already put transport or testing restrictions into place prior to the announcement of the federal order.

Even with the additional testing requirements, USDA emphasized that the current risk to the public remains low. In addition, the virus is associated with little to no mortality among dairy cattle.