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We Don't Know A Lot About Dogs And Ebola — But We Should

Excalibur, the dog that belonged to the Spanish nurse infected with Ebola, bayed from its balcony in Madrid before being euthanized on Oct. 8.
Andres Kudacki
Excalibur, the dog that belonged to the Spanish nurse infected with Ebola, bayed from its balcony in Madrid before being euthanized on Oct. 8.

Spanish health authorities seem as if they have no heart. They euthanized Excalibur, a dog that could have caught Ebola from his owner, the Spanish nurse who was diagnosed with the virus this week.

But the question of Excalibur's fate is a lot more complicated than just ... Awww, how could they put down a cute dog?

For a better understanding, we turned to Dr. Amesh Adalja. A specialist in infectious diseases, he's a senior associate at the University of Pittsburgh Medical Center's Center for Health Security, and he's having a very busy week, fielding interview requests to talk about Excalibur while attending the thirdannual IDWeek for infectious disease experts. Adalja told us what is already known about dogs and Ebola (very little, it turns out) and why we need to know a lot more.

So what do we know about dogs and Ebola?

We know about Ebola in humans. We know bats. We know antelopes. We know non-human primates. There's not a lot of work done with dogs.

Do you think a dog could transmit Ebola to a human?

We know Ebola is transmitted through blood and body fluids, and people with Ebola are only infectious when symptomatic. But that's based on human data. We don't really know what the role of dogs is in Ebola transmission. Yet dogs are mammalian species and we know viruses – and Ebola — can infect multiple mammalian species.

So it's reasonable that Spanish health authorities are worried that the dog may have been infected. I think [the authorities] are trying to be proactive and not open up a whole new realm of transmission, and that's why the suggestion is that they euthanize the dog.

Couldn't you just test the dog for Ebola?

We don't have diagnostic tests for dogs. We don't know what symptoms dogs might have. What if dogs don't experience symptoms?

And the dog can't tell you, 'I've got a fever' or 'I have muscle aches and pains.' So you have to be measuring temperatures — that is, if dogs even have same fever response as humans. It's very hard to translate what we do for [evaluating] humans to dogs.

Yet we humans love our dogs, which makes us want to keep Excalibur alive.

People are very attached to animals. It's hard for them to think about this [proposed euthanization].

Couldn't you keep the dog in quarantine?

That's very hard to do. Is the incubation period the same in a dog as a human? Does the virus follow the same type of spread inside [a dog's] body? The way we test for virus in the blood – is it the same for dogs as for humans?

All our protocols and algorithms work on primates. It's unclear to me how to translate that to canines and do it with certainty that would ensure the dog wasn't infected or poses no risk.

We know, for example, that in humans, Ebola remains in the semen for three months. What if [the virus] remains in the dog's semen for three months? We can tell a human to refrain from sex or practice safe sex but how do you that in a dog? Even if a dog doesn't have symptoms, it may have a mild case of Ebola that can transmit to other dogs if it has sex with other dogs.

What about the fact that saliva is a body fluid [that can transmit Ebola]? Dogs do a lot of licking, they lick people's wounds.

And that's never a good idea?

There's a risk of infection in general.

Your view of the Spanish decision to euthanize?

I understand a whole bunch of considerations are in play. We're really in uncharted water.

Definitely there is enough unknown that Spanish public health authorities are justified in their concern.

And it sounds as if there's no place for this dog to go.

I don't know what life that dog could have – perhaps as an experimental animal to understand what the disease does. I do hope we learn from this experience irrespective of the outcome about what Ebola does in dogs.

Why is that important?

We heard that during the quarantine in West Point [Liberia], dogs were eating the bodies of the deceased. If we have these situations where bodies are lying in the streets of Africa, it's important to know the virus's role in different animal species help design control strategies and understand the real scope of the disease.

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Marc Silver
Marc Silver, who edits NPR's global health blog, has been a reporter and editor for the Baltimore Jewish Times, U.S. News & World Report and National Geographic. He is the author of Breast Cancer Husband: How to Help Your Wife (and Yourself) During Diagnosis, Treatment and Beyond and co-author, with his daughter, Maya Silver, of My Parent Has Cancer and It Really Sucks: Real-Life Advice From Real-Life Teens. The NPR story he co-wrote with Rebecca Davis and Viola Kosome -- 'No Sex For Fish' — won a Sigma Delta Chi award for online reporting from the Society of Professional Journalists.