The coronavirus which has infected people around the globe may be dominating headlines, but related infections among livestock, including horses, have been reported for years.
Coronavirus infections are well known to livestock and poultry producers. Infections are also reported in horses, although the Equine Disease Control Center in the United States describes their frequency as low.
The Centers for Disease Control and Prevention (CDC) says common human coronaviruses usually cause mild to moderate upper-respiratory tract illnesses, such as the common cold.
Most people get infected with one or more of these viruses at some point in their lives.
But the new coronavirus, dubbed Covid-19, first detected in Wuhan City, in Hubei Province, China, is a far different challenge, with a growing death toll, and growing evidence that its containment may not be successful.
“Coronavirus is a common virus in livestock herds and poultry flocks seen routinely worldwide,” says veterinarian Heather Simmons, associated director of the Institute for Infectious Animal Diseases, which is under the wing of the Texas A&M University System.
“In wildlife, bats are known to carry over 100 different strains of coronavirus, and wild civets are the source of the coronavirus that causes SARS (Severe Acute Respiratory Syndrome), first reported in China in 2002-2003.
“Although our understanding is still limited, wild pangolins (a scaly anteater) sold at live markets may be associated with the recently reported coronavirus outbreak in China.”
Bats, civets and pangolins are all commonly sold at live markets in China, she said.
Coronaviruses from wildlife are dangerous since they have the potential to mutate, adapt and spill over to new species, including humans.
“That is the concern now; this new strain of coronavirus has emerged to cause disease in humans,” she says.
“It is important to create an understanding of the difference between coronaviruses occurring in domestic livestock and poultry compared to coronaviruses that spill over from wildlife to humans.”
Simmons said, to date, the coronaviruses in livestock are not considered reportable diseases because their main effect is as an economic burden to livestock producers.
They are known to occur worldwide annually, with some of the most common coronaviruses found in production animals, including the scours and winter dysentery in beef and dairy cattle, porcine respiratory coronavirus in swine and avian infectious bronchitis in poultry.
The World Health Organization has reported that while another coronavirus, MERS-CoV, is known to be transmitted from dromedary camels to humans, other coronaviruses circulating in domestic animals have not yet infected humans.
“That’s what is very important to understand at this time,” Simmons says. “We have been dealing with these diseases for a long time but as of yet, we have not seen cases worldwide transmitted from livestock to humans or vice versa.”
Coronaviruses in livestock and poultry are generally considered to have low mortality, Simmons says.
They affect either the respiratory system or the gastrointestinal system, depending on the species and the age of the animal.
Equine Coronavirus (ECoV) is usually a mild infection, but death can occur in complicated cases, according to the Equine Disease Control Center.
Signs include fever, lack of appetite, depression, colic, laying down frequently, diarrhea in some cases, and a low white blood cell count.
Complications in rare cases include protein loss, dehydration, neurologic signs, recumbency that can progress to an inability to stand, and death.
Supportive care is the primary treatment, with intravenous fluids given in more severe cases.
The prognosis is usually good. Indeed, most infected animals will not even show clinical signs.
Equine Coronavirus is spread when feces from an infected horse is ingested by another horse, either directly in a pasture or via contaminated objects such as stalls, manure forks or the like.
Its incubation period is 2 to 4 days.
In calves, diarrhea commonly occurs in animals under three weeks of age due to a lack of obtaining antibodies when the calf does not get enough colostrum from the mother in order to build up immunity.
Clinical signs include severe dehydration and diarrhea. The severity of the clinical signs depends on the age of the calf and their immune status. This is often seen by producers in the winter months as the virus is more stable in cold weather.
The second clinical syndrome, winter dysentery, is found in adult cattle.
Clinical signs include bloody diarrhea with decreased mild production, loss of appetite with some respiratory signs. Bovine coronaviruses can also cause mild respiratory disease or pneumonia in calves up to six months. The virus is shed in the environment through nasal secretions and through feces.
There are multiple coronaviruses that affect swine. Like cattle, they affect the respiratory or gastrointestinal tract.
In sows and piglets, porcine respiratory coronavirus usually presents with no clinical signs. If clinical signs do occur, it may be a transient cough within the herd and the spread of this disease occurs through aerosolized methods.
In poultry, infectious bronchitis virus, or IBV, is a rapidly spreading respiratory disease in young chicks. Clinical signs in laying hens include reduced production, eggshell abnormalities and decreased internal egg quality.
Livestock producers should consult with a veterinarian for treatment. Treatment in livestock herds and poultry flocks typically includes supportive therapy of fluids. Antibiotics are not indicated for viral infections but may be used if a secondary bacterial infection occurs.
The Equine Disease Communication Center factsheet on Equine Coronavirus can be read here.