Evaluation for SARS-CoV-2 Testing in Animals

Summary of Changes

Key Points

• This guidance was developed for use by state public health veterinarians, state animal health officials, veterinarians, biologists, and wildlife health specialists.
• The decision to test an animal as part of an epidemiologic investigation, including companion animals, livestock or production animals, zoo animals, or wild animals (both captive and free-ranging), should be agreed upon using a One Health approach that includes appropriate local, state, and/or federal public health and animal health officials.
  • Pet owners interested in pursuing testing for their animals should consult their veterinarian.
• Veterinarians should use their clinical judgement, including considering other common causes of illness, when deciding whether to test animals for SARS-CoV-2.
• Testing wildlife for SARS-CoV-2 is appropriate for surveillance and other activities to ensure the health of threatened or endangered species.
• Testing of experimentally infected animals is not addressed in this document.

Considerations for testing animals for SARS-CoV-2

Currently, the risk of animals spreading COVID-19 to people is low. In some situations, mostly during close contact, people have spread SARS-CoV-2 to certain types of animals, including companion animals (cats and dogs), animals in zoos and aquaria (big cats, great apes, mustelids), farmed mink, and wildlife. There have also been reports of infected animals such as mink, hamsters, and deer spreading the virus to people when in close contact, but this is rare.

Veterinarians should use their clinical judgement, including considering  other common causes of illness, when deciding whether to test animals for SARS-CoV-2.

The decision to test an animal as part of an epidemiologic investigation, including companion animals, livestock or production animals, zoo animals, or wild animals (both captive and free-ranging), should be made collaboratively using a One Health approach that includes local, state, and/or federal public health and animal health officials, as well as state wildlife veterinarians where free-living wildlife are concerned. Pet owners interested in pursuing testing for their animals should consult their veterinarian. Veterinarians should contact their state public health veterinarian or the designated state official responsible for animal-related issues in public health, and/or their state animal health official  to discuss testing. Veterinarians should report any animal that tests positive for SARS-CoV-2 to these same health officials.

Animal testing for SARS-CoV-2 is available at veterinary diagnostic laboratories, including members of USDA’s National Animal Health Laboratory Network.

Confirmatory testing through USDA’s National Veterinary Services Laboratories (NVSL) is required for all animals except domestic cats and dogs from state, territorial, local, and tribal jurisdictions that have previously confirmed SARS-CoV-2 in cats and dogs. Confirmatory testing is conducted to monitor the virus and to fulfill international reporting requirements based upon the USDA case definition. Because virus monitoring efforts remain a priority, NVSL continues to support sequencing of all cat or dog samples that meet testing criteria.

USDA is responsible for confirming and reporting any new animal species that test positive for SARS-CoV-2 in the United States to the World Organisation for Animal Health (OIE) , uploading sequence information to public databases, and posting all confirmed cases of SARS-CoV-2 on their public dashboard: Confirmed Cases of SARS-CoV-2 in Animals in the United States.

Clinical criteria for SARS-CoV-2 testing in animals

Like people, some animals with SARS-CoV-2 infection do not have any signs of illness, while others may have respiratory and/or gastrointestinal illness.

Clinical signs consistent with SARS-CoV-2 infection in animals include:

• Fever
• Coughing
• Difficulty breathing or shortness of breath
• Lethargy
• Sneezing
• Nasal discharge
• Ocular discharge
• Vomiting
• Diarrhea

Veterinarians should identify if an animal has been exposed to SARS-CoV-2 and if the animal has clinical signs consistent with SARS-CoV-2 infection. Table 1 describes epidemiological risk factors and clinical features that can help guide decisions regarding animal testing.

If One Health partners determine that testing an animal for SARS-CoV-2 is appropriate, coordination between One Health partners will be needed. Refer to USDA’s Testing and Reporting page for sample collection, transport, storage, and test result reporting.

Table 1: Criteria to Guide Evaluation and Laboratory Testing for SARS-CoV-2 in Animals

(This table is not intended to be prescriptive but should help guide testing priorities.)

Biological sample collection and testing

Preferred samples for virus nucleic acid testing and isolating live virus include nasal swab, oropharyngeal swab, and/or rectal swab. Samples may also be taken from internal organs collected post-mortem, or a fecal sample may be used in situations where direct sampling is not possible or may compromise animal welfare. Serum may also be collected for antibody testing where available. Contact the laboratory accepting diagnostic samples in advance for instructions on proper sample collection, storage, and transport, and use appropriate personal protective equipment when collecting samples.

Laboratories testing for SARS-CoV-2 should have established protocols and conduct testing under appropriate biosafety conditions. There are currently several molecular and serologic assays in use at veterinary diagnostic laboratories that are  useful across multiple susceptible animal species.

Additional considerations for testing free-ranging North American wildlife

Some species of wildlife can be infected with SARS-CoV-2, and there is evidence that some free-ranging wildlife have been infected in the United States. Testing may be useful for improving understanding of the epidemiology of the virus in wildlife populations and in applying necessary management actions. These recommendations can be applied to wildlife in human care for research or rehabilitation.

Wildlife health specialists or others conducting surveillance and research in wildlife should use their clinical judgement and consider other causes of morbidity and mortality when deciding whether to test animals for SARS-CoV-2.

Note: The testing of wildlife for research purposes is beyond the scope of this document.  Please refer to the OIE Considerations for sampling, testing, and reporting of SARS-CoV-2 in animals for additional information.

When to consider testing wildlife

Guidance provided in Table 1 are applicable to testing free-ranging wildlife. Additional scenarios to consider testing wildlife include when:

1. Conducting epidemiologic case investigations where wildlife are known or suspected to be associated with spread to or from people or other species.
2. Opportunistic samples are available to detect the presence of SARS-CoV-2 in wildlife populations, such as in hunted and/or trapped animals sampled for other purposes, or animals that are found dead or are euthanized.
3. Investigating threatened and endangered species or species of special concern to prevent SARS-CoV-2 infection spreading in endangered and vulnerable populations.

Footnotes

¹ Exposure is defined as:

• Being within approximately 6 feet (2 meters) of a person with suspected or confirmed COVID-19 starting from 2 days before the person’s illness onset (or, for asymptomatic human patients, 2 days before positive specimen collection) until 10 days after the date infection is identified.
• Having direct contact with infectious secretions from a person with suspected or confirmed COVID-19 starting from 2 days before the person’s illness onset (or, for asymptomatic human patients, 2 days before positive specimen collection) until 10 days after the date infection is identified. Direct contact could include an animal being coughed, sneezed, or spit on by an infected person or sharing food or consuming something that was recently contaminated with an infected person’s mucous or saliva.

² The International Union for the Conservation of Nature (IUCN) governs an assessment of the status of species ranging from “critically endangered” to “least concern”: https://www.iucnredlist.org/

Previous Updates

Updates as of October 21, 2021

• Recommendations were updated to include testing animals with an epidemiological link to SARS-CoV-2 (i.e., exposure to people or animals with infection), regardless of the animal’s clinical presentation.
• New recommendations applicable specifically to farmed mink have been included.

Updates as of March 17, 2021

• Guidance on evaluation for SARS-CoV-2 testing in animals was combined with guidance for SARS-CoV-2 testing in North American wildlife.
• Updates were made to reflect the new confirmatory testing process for animals.

Updates as of August 12, 2020

• Updates were made to the footnotes for Table 1 to clarify the definition of an animal’s exposure to SARS-CoV-2.