Tests conducted by the USDA National Veterinary Services Laboratories (NVSL) were unable to verify SARS-CoV-2 infection in a pet Pug in North Carolina, NVSL officials said Wednesday.
On April 28, multiple media outlets reported the pet Pug had positive results of a quantitative PCR (aPCR) test for SARS-CoV-2. The NVSL then tested the original sample, and collected and tested additional samples, in an effort to confirm the presumptive positive result. NVSL officials shared the results on Wednesday (May 27), saying they did not verify infection in the dog. No virus was isolated, and there was no evidence of an immune response based on a virus neutralization test, according to the NVSL.
The Pug belongs to a family whose members were tested for the virus as part of a voluntary Duke University research study of COVID-19-positive households in North Carolina. Media reports indicated family members recalled the Pug had exhibited mild and transient clinical signs of disease, including coughing and an episode of not wanting to eat a meal. But it appears the dog was not evaluated by a veterinarian at that time.
Based on the results available from the NVSL, it appears the weak detection of viral RNA by PCR may be the result of contamination from the COVID-19-positive household.
Recommended SARS-CoV-2 testing protocol
Because of the wide range of potential common causes for respiratory and gastrointestinal illness in dogs, and because infection of household pets with SARS-CoV-2 appears uncommon, veterinarians should evaluate patients to rule out more common causes of illness before evaluating pets for SARS-CoV-2.
Once common causes are ruled out, then testing for SARS-CoV-2 typically involves collecting samples from the nasal cavity, mouth, and possibly the rectum. It’s important that samples be collected in such a way as to avoid environmental contamination and to support accurate results. Directions for collecting samples are available from the USDA.
The approach to SARS-CoV-2 testing should be confirmed via consultation with a state public health veterinarian or state animal health official. The collection of samples must be appropriate, and different states have different requirements as to where samples can be submitted for testing.
COVID-19 is classified as an emerging disease by the World Organisation for Animal Health (OIE). As such, presumptive positive results of testing for SARs-CoV-2 in animals must be confirmed by the USDA NVSL. Confirmed positive results are then reported to the OIE.
What this case shows
This case serves as a good reminder to veterinarians of the importance of following a logical approach to diagnosis in cases of suspected SARS-CoV-2 in animals. A necessary part of the diagnostic workup is consultation with the state public health veterinarian or designated state animal health official. The AVMA has created a decision tree to assist.
AVMA’s COVID-19 resource center provides more information about testing for SARS-CoV-2 in animals, along with a handout to help with client communication about testing. Veterinary team members also can view a free webinar on AVMA Axon that delves into the guidance for testing animals for SARS-CoV-2.
See all of AVMA's COVID-19 resources at avma.org/Coronavirus.