SARS-CoV-2 Infection in Dogs and Cats from Southern Germany and Northern Italy during the First Wave of the COVID-19 Pandemic

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has affected millions of people globally since its first detection in late 2019. Besides humans, cats and, to some extent, dogs were shown to be susceptible to SARS-CoV-2, highlighting the need for surveillance in a One Health context. Seven veterinary clinics from regions with high incidences of coronavirus disease (COVID-19) were recruited during the early pandemic (March to July 2020) for the screening of patients. A total of 2257 oropharyngeal and nasal swab specimen from 877 dogs and 260 cats (including 18 animals from COVID-19-affected households and 92 animals with signs of respiratory disease) were analyzed for the presence of SARS-CoV-2 RNA using reverse transcriptase real-time polymerase chain reaction (RT-qPCR) targeting the viral envelope (E) and RNA dependent RNA polymerase (RdRp) genes. One oropharyngeal swab from an Italian cat, living in a COVID-19-affected household in Piedmont, tested positive in RT-qPCR (1/260; 0.38%, 95% CI: 0.01–2.1%), and SARS-CoV-2 infection of the animal was serologically confirmed six months later. One oropharyngeal swab from a dog was potentially positive (1/877; 0.1%, 95% CI: 0.002–0.63%), but the result was not confirmed in a reference laboratory. Analyses of convenience sera from 118 animals identified one dog (1/94; 1.1%; 95% CI: 0.02–5.7%) from Lombardy, but no cats (0/24), as positive for anti-SARS-CoV-2 receptor binding domain (RBD) antibodies and neutralizing activity. These findings support the hypothesis that the prevalence of SARS-CoV-2 infection in pet cat and dog populations, and hence, the risk of zoonotic transmission to veterinary staff, was low during the first wave of the pandemic, even in hotspot areas.

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“…Markedly, animals infected with the delta variant shed virus for up to 14 days post infection, four days longer than other strains [ 25 ]. Serological studies have detected circulating SARS-CoV-2 antibodies in canines, including in 43.9% of dogs in Croatia as well as a single dog in Italy [ 27 , 28 ]. Furthermore, molecular detection and sequencing identified an alpha variant (B.1.1.7) virus from an asymptomatic dog in Spain [ 29 ].…”

Myocardial Injury Complicated by Systolic Dysfunction in a COVID-19-Positive Dog

“…Concerning epidemiological data from our country, three large-scale Italian surveys conducted on domestic pets living either in SARS-CoV-2-positive households or in geographic areas severely affected by COVID-19 reported a seroprevalence in dogs of 1.1–3.3% [ 5 , 8 , 17 ]. Interestingly, in two of these studies, seroprevalence was higher among animals living in close contact with SARS-CoV-2-positive owners [ 5 , 8 ].…”

“…In two of the aforesaid large-scale Italian surveys, both serological and molecular tests were performed [ 5 , 17 ]. Intriguingly, all animals tested by PCR gave negative results, including those animals living in households with confirmed COVID-19 human infection, those with positive serological results and those with clinical signs [ 5 , 17 ].…”

“…Although such zoonotic disease has probably disseminated mainly by human-to-human transmission, the existence of hundreds of millions of companion animals living closely with humans raises the question of their potential role in the outbreak [ 1 , 2 , 3 , 4 ]. Accordingly, several studies have been recently performed in dogs and cats in many countries [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ], demonstrating their susceptibility to this infection. However, it is important to acknowledge that the majority of these studies are serological and/or molecular surveys primarily aimed at evaluating the transmission of SARS-CoV-2 among domestic animals, not the related clinical compromise [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ].…”

“…Accordingly, several studies have been recently performed in dogs and cats in many countries [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ], demonstrating their susceptibility to this infection. However, it is important to acknowledge that the majority of these studies are serological and/or molecular surveys primarily aimed at evaluating the transmission of SARS-CoV-2 among domestic animals, not the related clinical compromise [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. Consequently, to date, there is little evidence to determine how commonly SARS-CoV-2 naturally infected dogs and cats develop clinical signs and to characterise the clinical manifestations of the viral infection in these species.…”