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.
• Routine testing of animals for SARS-CoV-2, the virus that causes COVID-19 in humans, is not currently recommended.
• The decision to test an animal, 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 with the appropriate local, state, and/or federal public health and animal health officials.
• This document provides recommendations to guide priorities for animal SARS-CoV-2 testing given limited resources.
• Veterinarians are encouraged to consider other, more common causes of illness in animals and should use their clinical judgement when deciding whether to test animals for SARS-CoV-2.
• Testing wildlife for SARS-CoV-2 may be appropriate for morbidity and mortality event-based surveillance, ensuring the health of threatened or endangered species, or for research purposes.

Considerations for testing animals for SARS-CoV-2

The decision to test an animal, 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 between local, state, and/or federal public health and animal health officials, including state wildlife veterinarians where free-living wildlife are concerned. Animal testing for SARS-CoV-2 is available if public health and animal health officials agree the animal’s case merits testing. Table 1 (below) is not intended to be prescriptive, but should help guide priorities given limited resources. Routine testing of animals for SARS-CoV-2 is not recommended.

Currently, the risk of animals spreading COVID-19 to people is considered to be low. In some situations, mostly during close contact, people have spread SARS-CoV-2 to certain types of animals, including pet cats and dogs.

Veterinarians are encouraged to consider other, more common causes of illness in animals and should use their clinical judgement when deciding whether to test animals for SARS-CoV-2. To discuss testing an animal for SARS-CoV-2 in certain circumstances, veterinarians should contact their state public health veterinarianexternal icon¹ or designated state official responsible for animal-related issues in public health; and/or their state animal health officialexternal icon².

Clinical criteria for SARS-CoV-2 testing in animals

Clinical criteria for considering testing for SARS-CoV-2 in animals is based on what is currently known about SARS-CoV-2 and COVID-19 and is subject to change as additional information becomes available. Visit CDC’s COVID-19 and Animals page for the most up-to-date information on SARS-CoV-2 infection in animals.

Humans with COVID-19 often have symptoms that appear 2-14 days after exposure and include fever, cough, and shortness of breath. Like people, some animals with SARS-CoV-2 infection are asymptomatic, while others may present with a combination of respiratory or gastrointestinal illness.

Clinical signs suspicious of SARS-CoV-2 in animals include:

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

Veterinarians should use their best judgment to determine if an animal has been exposed to people with suspected or confirmed COVID-19 and if the animal has clinical signs compatible with SARS-CoV-2 infection (see Guidance for Veterinarians for additional information). Table 1 describes epidemiological risk factors and clinical features that can help guide decisions regarding animal testing.

If public health and animal health² officials determine that testing an animal for SARS-CoV-2 is appropriate, coordination between One Health partners will be needed. Refer to USDA’s FAQsexternal icon for sample collection, transport, storage, and result reporting. If samples are sent to state animal health, university, or private laboratories for initial testing, duplicate samples should be collected because any positive samples must be confirmed through additional testing by USDA’s National Veterinary Services Laboratories (NVSL). USDA is responsible for reporting any new animal species that test positive for SARS-CoV-2 in the United States to the World Organisation for Animal Health (OIE)external icon.

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

NOTE: Veterinarians are encouraged to consider other, more common causes of illness in animals and use their clinical judgement when deciding whether or not to test animals for SARS-CoV-2.

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. Contact the laboratory accepting diagnostic samples in advance for instructions on proper sample collection, storage, and transport, and use appropriate personal protective equipment external iconwhen collecting samples.

Laboratories testing for SARS-CoV-2 should use a validated test, have established protocols, and conduct testing under appropriate biosafety conditions. Currently, there is little information on the sensitivity or specificity of various diagnostic assays among different animal species, and there is no standardized, validated test in animals. Therefore, decisions relying on the ability to predict the true presence or absence of the virus—for example, in situations when wildlife are released from captivity—should be considered in this context.

Testing in North American wildlife

Despite concerns about human-to-wildlife transmission of SARS-CoV-2, routine testing for the virus in free-living or captive North American wildlife species is not currently recommended. However, there may be situations in which testing should be considered. This information may be useful for improving understanding of the epidemiology of the virus in wildlife populations and in applying necessary management actions. These recommendations do not apply to non-domestic species in human care (e.g., zoological facilities) except when free-living wildlife are temporarily in human care for research or rehabilitation.

Before testing sick or dead wildlife for SARS-CoV-2, wildlife health specialists are encouraged to consider other, more common causes of morbidity and mortality in wildlife and use their clinical judgement when deciding whether or not 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 animalsexternal icon for additional information.

When to consider testing a wild animal

Consider testing a wild animal when:

1. Morbidity and mortality event-based surveillance including detection in wildlife with clinical signs or post-mortem lesions consistent with SARS-CoV-2 infection and in animals that are found dead or are euthanized when there is cause for suspicion of previous exposure to SARS-CoV-2.
2. Threatened or endangered species or species of special concern, particularly wildlife with clinical signs consistent with SARS-CoV-2 infection and testing to prevent SARS-CoV-2 infection in endangered and vulnerable populations.

Footnotes

¹ Some jurisdictions do not have state public health veterinarians, or geographic, resource, or time limitations may prevent a state public health veterinarian from managing a situation involving an animal.
² State animal health officials should contact state wildlife officials for decisions concerning non-captive wildlife.
³ 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.

⁴ 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/external icon

Previous Updates

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 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.