Excalibur is no more.

The dog who belonged to the Spanish nurse infected with Ebola has been killed by Spanish authorities, Madrid's health department tells Mashable.

Earlier Wednesday, dozens of animal rights supporters protested outside the Madrid apartment where Excalibur and his owners lived, as the dog howled from a balcony.

Excalibur, the dog of the Spanish nurse infected with Ebola, barks from his balcony in Madrid on Wednesday. Image: Andres Kudacki/Associated Press

But Spanish authorities said Excalibur had to be euthanized because they didn't want to risk him transmitting Ebola to anyone else. It's unclear whether dogs could be infected with the disease, though one study suggests they could carry it and not show symptoms.

PACMA, an animal rights political party that organized the protests, confirmed the dog's death in a tweet.

"We can confirm the bad news. Excalibur has been put down. Thanks to your hearts for all the support, we'll keep working for [the animals]," it said.

Ahora sí confirmamos las malas noticias. Excalibur ha sido sacrificado. Gracias de corazón por tanto apoyo. Seguiremos trabajando por ellos. — PACMA (@PartidoPACMA) October 8, 2014

The group released a video showing the moment the dog was taken away — although it was unclear if it was dead or alive — as protesters swarmed the van and were pushed back by Spanish police.

PETA's UK arm condemned the Spanish authorities decision.

"PETA is sad to hear that a dearly loved dog was destroyed because of the Ebola scare, even though no one can point to any evidence that dogs can transmit Ebola and efforts could have been made to quarantine him," PETA UK Director Mimi Bekhechi told Mashable. "The last thing that this nurse needs is to learn that a family member has been lost, even if, as we all hope, her own life is saved. We appeal for common sense and mercy to prevail if such a case arises in the future."

Excalibur's owner, a nurse, remains in the hospital with Ebola. Her husband is in quarantine.

“We cannot take the risk,” said Felipe Vilas, head of the Madrid Official College of Veterinarians, whose criteria were reportedly the determining factor in the authorities' decision to put the animal down, according to the Spanish newspaper El Pais.

“This measure is more than justified, no matter how tough it may appear,” Vilas further explained. “The protection of the population is the most important factor here. No matter how small the risk, the logical step is to destroy the animal.”

The animal rights organization People for the Ethical Treatment of Animals called that decision unfair. "PETA is not aware of any evidence that dogs can transmit Ebola, but even if they can, it seems contrary, unfair and upsetting that while all efforts are being made to save the afflicted woman, none will be made to save Excalibur," Mimi Bekhechi, director of PETA UK, said in a statement.