As rescuers comb the ash-covered landscape looking for people after Indonesia's Mount Semeru erupted earlier this month, volunteers are searching for even more vulnerable survivors: cats, cows and other animals.

The disaster killed 48 people, according to the latest toll, and rescuers are still seeking bodies in the mud and rubble.

As deadly ash destroyed villages in East Java's Lumajang district, at least 767 cows also died, while 648 sheep were killed in sheds and thousands of chickens were buried by the mudflow, according to authorities.

Satria Wardhana, along with a team of 15 volunteers from the Centre for Orangutan Protection (COP), has so far rescued and treated 76 cows and scores of goats and sheep abandoned by villagers who fled the area.

"We only evacuated animals who have owners. For strays, if they are injured, we treat them on the spot," Wardhana told AFP in Curah Kobokan, the village closest to the volcano.

Volunteers are searching for even more vulnerable survivors after the eruption: cats, cows and other animals
Volunteers are searching for even more vulnerable survivors after the eruption: cats, cows and other animals AFP / ADEK BERRY

The team evacuated two goats whose owners died and incinerated goat carcasses to prevent the spread of disease.

"We also... feed animals who survived, like chickens, dogs and cats," said Wardhana, who works in the disaster rescue division at COP.

Surviving cows, goats, sheep and cats have injuries such as burns on their ears and feet, said COP's veterinarian Dian Tresno Wikanti.

"Their ears are hairless as they burn easily. Many other animals also suffer from coughing," she said.

"Some of them are also stressed out and there's a goat that had a miscarriage. These animals are... dehydrated because it's hot here."

At least 767 cows died, while 648 sheep were killed in sheds and thousands of chickens were buried by the mud flow
At least 767 cows died, while 648 sheep were killed in sheds and thousands of chickens were buried by the mud flow AFP / ADEK BERRY

The vet also goes door-to-door in some of Lumajang's villages, checking the condition of injured animals.

In Sumber Mujur, Wikanti treated a cat that was trapped under rubble for four days, its paws seared by lava.

The cat's owner, Ryan, said he was happy that his pet was able to get speedy medical treatment.

"I ran to save myself and I didn't have time to take the cat. The medical team... said it was traumatised, but it's getting better now," he said.

In the same village, volunteers treated two evacuated cows, applying burn ointment and injecting vitamins.

For the team, saving the lives of animals is a part of being human.

"Animals are usually abandoned because the main target of a rescue is humans. That's why we are rescuing those who are forgotten," Wikanti said.

Rescuing animals can also help lessen survivors' trauma, said Wardhana.

"Psychologically, they will be more at ease because... their animals also survived."