Should a dog be euthanized for exposure to ebola?

Restingdog

One of the side stories of the ebola epidemic is the story of the dog in Spain, Excalibur, who was euthanized after her owner became ill with ebola (she contracted the infection while treating two ebola-infected patients repatriated from west Africa). She was living with her husband who also had to be quarantined at the nearby hospital, but the dog, authorities decided, had to be euthanized. In spite of protests from both husband and patient, demonstrations by animal rights activitists, and an online petition garnering nearly half a million signatures, the dog was put down two days after the ebola diagnosis.

It’s hard to blame the Spanish authorities for putting down the dog. Ebola has captured the imagination of the world more than any other infectious disease as one of the most terrifying ways to die. An outbreak of the disease in Spain would truly be scary even if health authorities are confident that such an outbreak could be contained. Therefore, Spanish authorities could take no chances and euthanized.

The decision to euthanize Excalibur stems from the nature of transmission of viruses between different animal species. It is generally difficult for viral infections to affect different species in the same way. For example, dogs never develop cold or flu symptoms after being exposed to such viruses. However, transmission between species is not unknown. Many flu viruses have evolved from the close proximity of humans with chickens and pigs. The West Nile virus affects humans and birds alike, and the rabies virus appears to affect all warm-blooded animals.

Numerous studies have been carried out in Africa about transmission of ebola to dogs. Dogs have no doubt have exposed themselves to ebola by eating infected bush meat, eating vomitus or feces of infected humans, and so on. Testing within outbreak zones identified ebola antibodies in dogs indicating they had been exposed and developed antibodies. However, no dogs have been known to become ill as a result of exposure.

Even if dogs do not become ill does not mean that they cannot transmit ebola. Two things can happen when dogs become infected with ebola: either their immune system eradicates the virus, or the virus thrives in the dog without triggering an immune response or making the dog sick. In the latter scenario, the dog then becomes a carrier of the virus meaning they can transmit the virus to humans without showing any symptoms. Humans, for example, are known carriers of the canine parvovirus meaning that they can harbor the virus asymptomatically and subsequently make their dog sick. The scenario in which dogs are carriers of ebola was what motivated Spanish authorities to euthanize Excalibur.

The canine studies in Africa, however, were unable to conclude if dogs can transmit the virus to humans or how long the virus remains in the dog’s body before its immune system can eradicate it. Indeed, how ebola first enters humans during an outbreak remains a mystery highlighting the caution exercised by Spanish authorities.

Many experts on epidemiology, however, felt that Excalibur’s death was excessive and unnecessary. Certainly, the dog at a minimum should have been quarantined but some pointed out that Excalibur could have provided valuable information on how ebola is transmitted to dogs and if so, whether dogs are a potential carrier of the virus. Moreover, Excalibur was 12 years old and could have been permanently quarantined within the couples’ home for the remainder of its life.

Dog lovers agree that officials could have showed more forethought. Why not quarantine the dog with the patients? Why not quarantine the dog and then euthanize it after the patients were out of danger allowing the patients to be with dog when it died? Perhaps not coincidentally, the patient’s condition deteriorated about the same time the dog was euthanized. It’s not known if she knew that the dog was put down when her health took a turn for the worse, but she must have been worried about the dog’s state of mind, surrounded by complete strangers, perhaps terrified of its surroundings, and wondering what happened to its family and home before it drew its last breath.