Coronavirus update

Emerging coronavirus strains and veterinary patients

Diagnostic update • April 2020

A novel coronavirus causing an outbreak of respiratory disease in humans has led to questions about the importance of this newly discovered virus, if any, to our veterinary patients. This guide provides summary information intended to answer some of the more frequently asked questions about the coronavirus. An understanding of coronaviruses and their transmission is rapidly evolving and we suggest that you check the reference sources provided at the end of this update for the most recent information.

Coronavirus disease 2019 (COVID-19) was first detected in China with an initial outbreak in the city of Wuhan. This disease is caused by a novel coronavirus named SARS-CoV-2 and is believed to have originated from bats. Since its emergence in late 2019, COVID-19 has spread to locations around the globe.^1-3

The SARS-CoV-2 virus, which causes COVID-19, is a unique coronavirus that infects the human respiratory tract and differs from previously identified coronaviruses that infect humans or veterinary patients. Coronaviruses are a large family of viruses consisting of multiple sub-groups that are commonly found in humans and other mammals, birds and reptiles.

Alpha and beta coronaviruses (including coronaviruses such as those responsible for the common cold in humans) usually infect mammals, while gamma and delta coronaviruses normally infect birds and fish. Many of the common coronaviruses causing disease in pets, such as feline enteric coronavirus, are alpha coronaviruses. SARS-CoV-2, responsible for this COVID-19 respiratory outbreak in humans, is a beta coronavirus.

Transmission of COVID-19 and pets

Leading public health authorities agree that COVID-19 is primarily a human disease that is transmitted directly from person to person in respiratory droplets.^1-4 Secondary transmission by touching a surface with the virus on it may also be possible, particularly from smooth surfaces such as plastic or metal.^5,6 Porous surfaces such as clothing and fur are thought to be less than ideal surfaces for fomite transmission.

Recent studies have demonstrated that cats and ferrets may be infected in experimental settings and transmit to other animals while dogs are generally resistant to infection, likely due to species differences in their ACE-2 receptors.^7-9 In isolated cases, reverse zoonotic (infected human to pet) transmission has been reported in cats, ferrets, and dogs.^10,11 Infection in cats and ferrets is often subclinical but may present with mild respiratory signs, fever and, in some cases, gastrointestinal signs. In these non-primary host species, infection seems to be of shorter duration than in humans. Unlike dogs and cats, mink have been identified as a species susceptible to infection by SARS-CoV-2 (for example, by infected humans in high population density situations such as mink farms), and could potentially pose as a reservoir of infection and viral mutation.¹² Although transient reverse zoonotic infections have been sporadically reported in dogs living with COVID-19 infected humans, no clinical signs have been reported in these dogs.^10,13 Pets are not believed to play a role in transmitting COVID-19 to humans.^1-4

An understanding of SARS-CoV-2 transmission and COVID-19 disease is rapidly evolving. 

Development of an IDEXX SARS-CoV-2 (COVID-19) RealPCR Test 

IDEXX Reference Laboratories has developed and validated a real-time PCR test to detect SARS-CoV-2 based on the published genetic sequences of the virus from the human outbreak.¹⁴ The IDEXX SARS-CoV2 (COVID-19) RealPCR Test targets the same nucleocapsid gene as the CDC (Centers for Disease Control and Prevention) assay but has been adapted with a unique alignment for use in animals. It has been carefully designed to avoid cross-reactivity with other veterinary-specific coronaviruses. Specificity studies confirm that there is no cross-reactivity with the new PCR test against common veterinary coronaviruses affecting companion animals. Likewise, currently available RealPCR tests for these veterinary coronaviruses were demonstrated to not detect the SARS-CoV-2 viral nucleic acid. 

During the initial four-week validation of the new SARS-CoV-2 (COVID-19) RealPCR Test, IDEXX tested more than 3,500 canine, feline and equine specimens submitted to IDEXX Reference Laboratories for respiratory RealPCR panels. Specimens were tested in parallel with three assays from the Centers for Disease Control and Prevention (CDC). A subset of faecal specimens submitted for diagnostic diarrhoea RealPCR panels were also evaluated as part of the cross-reactivity studies. The specimens originated from the United States and South Korea. Screening was expanded to Canada and European countries starting in mid-March, including areas with high rates of COVID-19 in the human population. 

SARS-CoV-2 specimen collection guidelines

It is encouraged that you consult with your state public health veterinarian  for the latest guidelines on safely collecting specimens prior to testing for SARS-CoV-2 in a pet. The use of personal protective equipment (PPE) including gloves, mask, gown and eye protection is recommended when collecting specimens from a pet in which SARS-CoV-2 infection is suspected.

The ideal specimen should be based on clinical presentation and purpose for testing. 

• For respiratory manifestations: deep pharyngeal swab (with visible organic material on swab; please rub firmly) and a conjunctival swab (wipe eye clean, swab inside of eyelid). If the patient is cooperative, a swab from the caudal nasal cavity may also be included. Please submit dry, plastic-stemmed swabs, without transport media; keep refrigerated. 
• For gastrointestinal manifestations: 3-5 g (1 g minimum) fresh faeces in a sterile container and deep pharyngeal swab (with visible organic material on swab; please rub firmly) and a conjunctival swab (wipe eye clean, swab inside of eyelid). Please submit dry, plastic-stemmed swabs, without transport media; keep refrigerated.
• No distinct clinical signs (e.g. public health investigations): 3-5 g (1 g minimum) fresh faeces in a sterile container and deep pharyngeal swab (with visible organic material on swab; please rub firmly), conjunctival swab (wipe eye clean, swab inside of eyelid) and caudal nasal swab, in the same tube.

Managing SARS-CoV-2 positive pets

COVID-19 is an internationally reportable disease. If a positive SARS-CoV-2 result is detected, the IDEXX RealPCR team will provide essential information (consistent with applicable privacy and other laws) to the public health and/or veterinary authorities. The submitting veterinarian is then responsible for providing additional clinical details to the local public health authorities as required by applicable law. Positive IDEXX SARS-CoV-2 (COVID-19) RealPCR tests will be further confirmed at a third-party government laboratory, according to regulatory guidance.

Positive PCR results in a pet from a COVID-19 positive household may result from either reverse zoonotic transmission of infection from the infected owner (or other infected human) to the pet or may reflect environmental contamination. It is important to interpret results based on history, clinical signs and the results of diagnostic tests for common veterinary pathogens. 

Infected pets should be treated symptomatically based on their clinical signs and monitored for evidence of secondary complications (e.g. bacterial infection). If respiratory signs are mild enough that hospitalisation is not required, it is recommended that the pet be isolated at home with its owner. If there is no history of human COVID-19 infection in the household, consultation with a public health authority is recommended to determine the best course for the testing of humans in the household and management of the infected pet. Repeat RealPCR testing in one to two weeks should be considered to confirm that the pet is no longer PCR positive before considering the household clear of infection or allowing the pet to mingle with other unexposed animals (especially cats or ferrets). 

Prevention of COVID-19 infection

Recommendations for prevention of the spread of COVID-19 are centred around preventing exposure. These include limiting person-to-person contact with sick individuals, limiting travel and attendance at gatherings of large numbers of people, regular hand washing and covering the mouth and nose when coughing or sneezing.^1,2

At this time, no antiviral medications have proven to be effective in the treatment of COVID-19. Similarly, no commercially available vaccines are currently indicated for the prevention of SARS-CoV-2 infection in humans or animals.

Although reverse zoonotic infection (humans to their pets) resulting in clinical disease is considered uncommon, the AVMA and CDC and other authorities globally recommend limiting contact with any pets if a pet owner has been diagnosed with COVID-19 infection as a precautionary animal health measure. If possible, another family or household member should provide daily care of the pet.