The impact of COVID-19 on pets, wildlife and livestock

Published on 31 August 2021

Coronaviruses (CoVs) not only cause a threat to humans, but also to livestock and pets.  They circulate in wildlife mammals and birds.  It is concerning that there is an emergence of new animal reservoirs of SARS-COV-2, the virus that causes COVID-19.  The latest animal to be infected with the novel coronavirus is the white-tailed deer (Odocoileus virginianus) from the eastern United States.  A survey showed the presence of antibodies against SARS-CoV-2 in the deer population.  It is speculated that the disease could have spread through contact with other infected wild animals, people or contaminated wastewater.  Even the predators of deer and domestic livestock like cattle are at risk, as they share water sources and pastures.

These viruses can remain in animals for a while, spill over to other animals, gather mutations, evolve into a new variant, and then jump back into people.  Zoonotic diseases are the ones passed from animals to humans.  According to CDC, it is estimated that 6 out of 10 infections are zoonotic in origin.  The reverse is also possible.  Anthroponosis or reverse zoonosis is when humans transfer diseases to animals.  Reverse zoonoses can also take bacteria, virus and parasites from humans to animals.

Influenza poses a threat to both canine and feline health.  Cats are susceptible to many avian influenza infections.  Companion animals like cats and dogs can host, sustain and transmit zoonotic viruses.  According to WHO, it is not yet known if a cat, dog or any pet can transmit COVID-19 to humans.  The fur of the animal can carry the virus should it come in contact with an infected sick person.  Research studies have shown that pet dogs and cats of covid-positive owners have SARS-CoV-2 antibodies.

Dogs

Two dogs – a Pomeranian and a German shepherd – had tested positive for the virus in Hong Kong.  The 17-year-old Pomeranian dog died after it was released from quarantine.  The dog tested weak-positive for the virus and showed no symptoms.

Cats

Pet cats in Belgium, UK and Hong Kong tested positive for COVID-19 after catching it from their infected owners.  Some cats showed classical signs of the disease including difficulty breathing, a week after the owner started to show symptoms.  The cats suffered from diarrhea and vomiting.  The virus was found in cat feces.  Compared to dogs, cats are at a higher risk of catching COVID-19.

Monkeys

Some primates can pick up COVID-19 from humans.  Great apes share about 98 percent of their DNA with human beings.  It is with the help of the ACE2 protein found on the surface membrane of cells, particularly in the airways, the novel coronavirus infects people.  The ACE2 protein of apes is similar to that of humans, which makes the apes vulnerable to COVID-19.  In a study, it was found that the 25 amino acids important for binding between ACE2 and the novel coronavirus spike protein were present in mammals the most, especially the Old World monkeys that include the gorillas, chimpanzees, bonobos, macaques, gibbons, and orangutans, as well as, humans.

Lions

In Arignar Anna Zoological Park, Vandalur, Tamil Nadu, ten Asiatic lions had tested positive for SARS-CoV-2 with the death of one animal.  One more animal had tested positive for Canine Distemper Virus (CDV).  In Bronx Zoo in New City, three lions had tested positive for COVID-19.  In May 2021, eight Asiatic lions had tested positive for COVID-19 in Nehru Zoological Park, Hyderabad, India.  It was stated that reverse zoonosis was the reason for their illness.  The staff at the zoo had tested positive for the virus.  According to research, stray cats too can spread COVID-19 to zoo animals.

Tigers

In June 2021, a 10-year-old male tiger died of covid-like symptoms with liver and kidney failure at Bhagwan Birsa Munda Biological Park, Ranchi, India.  The tiger developed fever and loss of appetite.  Four zookeepers had tested positive for COVID-19.  Four tigers at New York City’s Bronx Zoo had tested positive for coronavirus, contracting it from an asymptomatic caretaker.  They had a cough, loss of appetite, nasal discharge and labored breathing.  A 10-year-old male tiger of the Pench Tiger Reserve in India succumbed to respiratory illness in April 2020.  It is to be noted that the virus in the air can reach up to 2 meters and remain alive in the air for three days.

Fish

The aquariums and zoos in New York had thousands of virus deaths.  Frozen salmon can harbor the infectious coronavirus for more than a week, according to Chinese researchers.  This makes the imported fish a potential source of infections.  Salmon samples could survive for eight days at 4 degrees Celsius (39 degrees Fahrenheit).  The fish are transported at temperatures between 0 to 4 degrees Celsius.  Traces of SARS-CoV-2 have been found on food packaging and containers too.

Minks

Minks are carnivorous mammals belonging to the family Mustelidae, which also includes weasels, otters and ferrets. Minks were found to retransmit SARS-CoV-2 back to humans in the mink farms.  Nearly 200 people were found to be infected with a mutant form of mink-related virus variant called Cluster 5.  To stop the virus from spreading, 20 million minks were culled in Denmark and Netherlands.  Cluster 5 mutation reduced the efficiency of human antibodies against COVID-19.  The ability of the virus to jump between minks and humans can very well lead to a recurring plague with newer mutations.  In mink farms that produce the prized mink fur used in clothing, the animals are crammed into battery cages with little freedom to move.

Other plagues

Bubonic plague:  Apart from COVID-19, several outbreaks of bubonic plague were detected in Inner Mongolia in China, El Dorado County in California and Africa in January 2021.  Bubonic plague is a bacterial disease that is spread by fleas living on wild rodents such as marmots, squirrels, and chipmunks.  The plague can be contracted by eating infected marmots.  Plague-infected fleas are carried by dogs and cats.

Avian Influenza:  Many states in India reported bird flu in January 2021.  Highly Pathogenic Avian Influenza (HPAI) was detected in many Asian countries, Europe, Russia, and the UK.  According to Food and Agriculture Organization (FAO), birds are the natural reservoirs of Avian Influenza (AI) viruses.  In December 2020, thousands of ducks had died in a Minjur poultry farm in Chennai, India.  In January 2021, there was another outbreak of the Avian Influenza – H5N8 – killing ducks in Kerala, India.  Nearly, 1800 migratory bar-headed geese died in Pong Dam Lake sanctuary in Himachal Pradesh, 4 lakh poultry birds died in Haryana, and hundreds of crow deaths were reported in Rajasthan.  When there is a wildlife bird sanctuary next to a poultry farm, there is always the danger of pathogen spillover between the free-living and domesticated birds.  China reported its first case of a rare strain of bird flu, namely H10N3, in a man from Jiangsu in May 2021.

Infectious Bronchitis Viruses:  There was an outbreak of Infectious Bronchitis Viruses (IBVs) in chickens, turkeys, guinea fowls, quails and wild birds.  It is a gammacoronavirus harbored by the avian species, the other one being deltacoronavirus.  These are mainly present in wild birds.

Cat Que Virus:  There was an outbreak of Cat Que Virus, which is an arthropod-borne virus called the orthobunyavirus, found in Culex mosquitoes, pigs and wild birds like jungle myna.  It is mainly reported in China and Vietnam.  The antibodies for Cat Que Virus were found in human serum samples in India.

African swine fever:  It is a hemorrhagic disease caused by a virus that is harmless to humans but deadly to pigs.  China’s porcine population has been severely affected by this disease that is currently raging.  Large pig stocks have been culled and the carcasses destroyed.  Small family farmers in China feed their hogs raw meat instead of superheated meat.  The affected pigs are sold off before they show symptoms and this is cited as the reason for the spread.

Animals aiding in the fight against COVID-19

Laboratory animal models:  Rhesus macaques, mice, hamsters, ferrets and cats are being used to study the coronavirus. Mice are genetically engineered to produce human ACE2 receptors which are used by the novel coronaviruses to latch onto human cells.  Such gene-edited mice, vulnerable to COVID-19, are used in therapeutic studies.  One study found that cats in adjacent cages caught the virus, confirming transmission via respiratory droplets.  Such animal models are the gold standard in studying protective immune responses to diseases, route and time of infection, vaccines, therapeutics, dosages, efficacy, and safety.

Horseshoe crab:  The horseshoe crabs, also called living fossils, which have been roaming the earth for the past 450 million years, are helping in the fight against COVID-19.  The blue blood of the horseshoe crab (Limulus) has immune cells called amoebocytes that have the power to coagulate very quickly.  These cells are very sensitive to toxic bacteria and have been widely used in testing vaccines and medications for safety.  A test called Limulus Amebocyte Lysate (LAL) is used to check for contaminants in vaccines.  A synthetic alternative to the blue blood amebocyte, called Recombinant Factor C (rFC), has been genetically engineered in a lab.

Llama, camel and shark:  The immune cells of llamas, camels and sharks make miniature antibodies, which are half the size of the standard antibodies.  Such mini-antibodies can be synthesized in the labs and used for the fight against COVID-19 through inhalable therapeutics.

Super-sniffer dogs:  Canines can detect COVID-19 with perfect accuracy from samples taken from mouth and windpipe and sweat and urine samples.  They can spot the infection even before the symptoms start.  Dogs have around 300 million scent receptors, compared to 5 to 6 million scent receptors in humans.  These super-sniffers are being deployed in airports and sports stadiums to screen for the disease.  The breeds of sniffer dogs included cocker spaniels, Chippiparai, German Shepherds, Belgian Malinoises, and Jack Russell terriers.  According to CDC, although a small number of animals, including dogs, have been infected with the virus that causes COVID-19, there is no evidence that animals play a significant role in spreading the virus.  It is speculated that viral illnesses, diabetes and cancer in the human body let off distinctive patterns of volatile organic compounds (VOCs).  The dogs are capable of picking up these scents.

Vaccines for animals

Carnivac-Cov is the world’s first animal vaccine from Russia for COVID-19.  The immunity can last for six months.  The clinical trials were carried out on dogs, cats, Arctic foxes, minks and other animals.  It is easier to vaccinate farm animals, but a lot harder in the case of wild animals in remote places.  Vaccines can be introduced into baits, which the wild animals feed on, but then the protection is only for the targeted animals.  Transferrable vaccines as pastes can be smeared on the fur of bats.  When bats groom other bats in the colony, the vaccines get passed around.  Transmissible vaccines consist of live modified viruses that cause weak infection in animals.  Different ways to spread immunity among wild animals should be investigated, which can eradicate pathogens in the wild populations.

To keep in mind

Pandemics most likely begin in animal farms close to wildlife sanctuaries and wet markets, especially the ones dealing with exotic animals.  Mass crowding of animals in Confined Animal Feeding Operations (CAFO) have been fertile grounds for disease outbreaks.  It is a threat to both the confined animals and human workers.  Dust and aerosols emanating from such farms can also make people sick.  Animal feces and urine often contain genetic evidence of viruses.

Similarly, slaughterhouses where people work closely together with animals, are also places where diseases can spread.  There is heavy use of antibiotics as a growth promoter and to keep the bacterial disease at bay from livestock.  Land-use change from natural habitats to agricultural or urban ecosystems also carries risks of zoonotic diseases.

In zoos, the animal houses have to be well maintained.  The animal feed should be bought from authorized slaughterhouses and stored in efficient cold storage facilities.  Ultraviolet disinfection should be carried out periodically.

The transmission of coronavirus does not occur through food.  These viruses are thermolabile and are susceptible to normal cooking temperatures (70°C).  General precautions should be followed, and raw, uncooked meat should be avoided.

The influenza virus that caused a pandemic in 2009 had a pig origin.  Phylogenetic studies and data analysis pointed to farms in Mexico that raised the infected pigs and the virus was traced to pigs imported from Europe.

As for the birds, they should be housed in such a manner that they do not come in contact with wild birds.  Best practices and biosecurity measures should be followed by farmers to keep the birds safe.

The risk of pet animal-to-human transmission is very small.  There are no threats from pets.  The owners should not abandon their pets.  On the other hand, infected individuals must keep away from their pets.  Snuggling, cuddling and sharing beds with pets should be avoided.

The lockdown due to COVID-19 helped the African rhinos in a big way.  South Africa, home to 80 percent of the rhino population, had reported a decline in the number of rhinos killed by poachers.  The COVID-19 lockdown had restricted the movement of poachers.

People must reduce their contact with wild animals and take utmost care of their pets and livestock.  Adopting a plant-based diet would help immensely, as well as, avoiding big game hunting.  Extractive industries, industrial farming, and urbanization should not take place at the expense of nature.  Invasive species negatively alter the environment.  Climate change, excessive pesticide use, electropollution and habitat loss are all well-documented threats to the web of life on earth.

The COVID-19 pandemic is teaching the world a new lesson.   Disturbing the ecological balance in one part of this hyperconnected world can have a ripple effect and will quickly lead to chaos everywhere.  People in pandemic lockdown have experienced languishing and the misery of being confined to a small space for long.  Imagine the animals in zoos and farms. Rapid human developmental activities cannot take place at the expense of nature and all its creatures.  If it should so happen, it comes with a heavy price tag, threatening the very fabric of social, cultural and economic stability of mankind.


Image Source: Pexels

References and Further Reading

Coronavirus (COVID-19) updates from Cats Protection

Zoonotic Disease: What Can I Catch from My Cat?

Zoonotic host diversity increases in human-dominated ecosystems

Horseshoe crab blood: the miracle vaccine ingredient that’s saved millions of lives

Cats may catch COVID-19 from sleeping on their owner’s bed

Influenza A Virus Infection in Cats and Dogs: A Literature Review in the Light of the “One Health” Concept

Structural Basis for Potent Neutralization of Betacoronaviruses by Single-Domain Camelid Antibodies

Coronaviruses in Avian Species – Review with Focus on Epidemiology and Diagnosis in Wild Birds

Broad host range of SARS-CoV-2 predicted by comparative and structural analysis of ACE2 in vertebrates

Detection dogs as a help in the detection of COVID-19 Can the dog alert on COVID-19 positive persons by sniffing axillary sweat samples ? Proof-of-concept study

Can dogs smell COVID? Here’s what the science says

If endangered primates disappear, so will their parasites. That’s actually a problem (23 September 2021)

Last updated on 26 September 2021


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