ARE DOGS AT RISK?
First, let me put your mind at ease that the current strains of Ebola virus cannot kill your dog or cat. That said, dogs and other pets are not totally without worry from Ebola.
You see the phrase “abundance of caution” in every Ebola report discussing pets. The real message behind that phrase is that there are many unknowns about Ebola and our four-legged babies.
Epidemiologists depend heavily on a study published in 2005 from an Ebola outbreak in the Gabonese Republic which ran from 2001 to 2002. French researchers had previously shown that the reservoir for Ebola virus consists of commonly-occurring animals in the vicinity. Gorillas, chimpanzees and duikers (a small antelope) were the main sources of human Ebola exposure as villagers dressed the kill of what they call “bushmeat.”
Prevention of future epidemics begins with data collection and analysis. In every outbreak there is a percentage of human cases with no exposure to a human Ebola patient or animal contact. Therefore, researchers look for other means of transmission such as respiratory tract (aerosol droplet) dissemination. They also investigate previously-unknown animal species that might be involved.
HOW DO DOGS BECOME INFECTED WITH EBOLA?
Dogs in many African villages are kept as pets and hunting dogs, but they are not fed; instead they must scavenge for food. They frequently catch and eat small animals as well as the body parts of animals their hunting owners discard. They lick the bleeding wounds and eat the vomitus of human Ebola victims.
It is in these ways dogs become exposed to the virus.
The French study evaluated 439 dogs, including 102 in France as negative controls (having had no possible exposure to Ebola). African dogs showed Ebola antibodies in their blood, which means that the Ebola virus had entered their bodies and the dogs’ immune systems had responded to the virus. The French researchers concluded that these dogs had become infected, although other scientists stop short of using the term “infected” and say only that the dogs were exposed and produced antibodies. The next statement is easily the most important for dog owners: “No circulating Ebola antigens or viral DNA sequences [parts of viruses] were detected in either positive or negative serum specimens, and attempts to isolate virus from these samples failed. These findings indicate either old, transient Ebola infection of the tested dogs, or antigenic stimulation.”
CAN MY DOG GIVE EBOLA TO ME?
In other words, not only were there no viruses in these dogs capable of causing human infection, there were not even any parts of viruses detectable.
Furthermore, it also helps to explain why dogs are not among the list of animals known to become ill from Ebola.
That said, many, many more dogs need to be tested to determine whether viable virus is ever released from the canine body. Only then will we be able to say with total assuredness that dogs exposed to Ebola are completely safe to be around humans. Such a study will be performed someday, but that information is not available yet, which is why extreme caution has been taken in the current outbreak.
WHY WAS THE DOG IN SPAIN PUT TO SLEEP?
Spanish officials have been widely criticized for euthanizing Excalibur, the dog belonging to the lone Ebola victim in Spain. The officials’ decision was based on current information, which is admittedly incomplete. Still, they were driven by “an abundance of caution.”
In the United States, officials in Dallas, Texas, took the approach of isolating Ebola-infected nurse Nina Pham’s dog, Bentley. An adorable Cavalier King Charles Spaniel, Bentley is being quarantined under extremely close observation. His caretakers provide playtime, but they wear the same protective suits that nurses and doctors caring for his “mom” wear. The time period for Bentley’s observation is 21 days. Given the above information, the selection of a 21-day time period seems arbitrary, except that 21 days is the usual incubation period in humans. That said, at least one expert questions the generally-accepted 21-day incubation period for people.
Bentley’s urine and stool will be tested for Ebola virus three times during his confinement. As of October 23, 2014, his first test was negative. (That’s the good one!)
One concern that health officials have is that pet owners who become ill might not seek medical attention for themselves lest their pets become victims of the system. That alone is reason enough to have a workable quarantine period for pets.
Following up on Dr. Greg McGrath’s Your Pet’s Doctor column on the topic of “One Medicine” last week, the same concept is being applied to Nina Pham and Bentley. Dean of the College of Veterinary Medicine (CVM) at Texas A&M University (TAMU), Dr. Eleanor Green, says, “One Health [TAMU’s specific program] refers to that inextricable link between animal, human and environmental health…Bentley and his owner demonstrate this.” Two CVM faculty members are in charge of Bentley’s care in Dallas, TX. Dr. Green goes on to say, “It will be better for her [Pham] if she has the confidence that Bentley is being well taken care of, too. That will make her better. We know there are very positive health effects from the interaction between animals and people.”
WHAT ABOUT OTHER PETS?
Experimentally, Ebola virus has been transmitted from infected pigs to nonhuman primates. Whether such transmission occurs in nature between pigs and monkeys or pigs and humans is unknown. What risk a Ebola-exposed pet Vietnamese potbellied pig might pose to its human owner is also unknown.
Little is known about Ebola’s relationship to cats.