A vegan blogger who has put her pet fennec fox on a vegan diet has sparked a massive backlash after photos of the animal looking thin were spread online.

YouTuber Sonia Sae from Barcelona has made her name online as an animal rights activist, offering tips for living vegan and encouragement for others to go vegan on her channel.

But recently her own animal-advocate audience has turned on her with a vengeance, and it's all down to how she has been treating her very own pet: a fennec fox named Jumanji.

Lifting up: Vegan blogger Sonia Sae from Barcelona has come under fire by animal activists who have criticized her for feeding her pet fennec fox a plant-based diet

Putting it out there: Sonia has made a name for herself online for her outspoken advocacy against eating animals

An example: Fennec foxes (such as this one in a Tel Aviv zoo) live on a mainly carnivorous diet in the wild, eating insects and small animals, as well as a tiny amount of plant-based foods

Sonia claimed that she rescued Jumanji from a breeder in 2014 and has been feeding him on a vegan diet consisting mostly of cat food for a number of years.

However, this goes against the natural diet of Fennec foxes, which are classified as mostly carnivorous.

In the wild, the animals' diet consists mainly of insects, small animals such as lizards and birds, and eggs. As a small portion of their diet they also can also eat plant-based foods like fruit and roots.

Sonia has regularly shared pictures of her pet online looking quite thin, as well as mentioned some health ailments he has experienced, manifesting in weight loss, hair loss and partial blindness.

Given the general knowledge of a fox's diet and the photographic evidence, many of Sonia's followers started to voice their belief that his vegan diet is the source of all of Jumanji's health troubles.

Causing concern: But Sonia's audience is now turning on her after suggestions emerged that the vegan diet she is feeding her fox Jumanji is making him deathly ill

Accusations: Criticism exploded after this post from a concerned viewer went viral

Lying down: Sonia has claimed that Jumanji's hair loss and therefore thin appearance is actually due to a 'skin allergy'

Concerns for the animal hit a fever pitch after a Facebook user named Alice Natanya Moore shared a number of photos of Jumanji and accused Sonia of animal abuse.

'Sonia has refused to listen to experts who are all appalled at her treatment of Jumanji and have contacted her regarding the health of her fennec fox,' Alice wrote in her post, which has been shared more than 22,000 times.

Alice also included photos of correspondence from animal rights groups such as Faithful Foxes and Ears.org seconding concern for Jumanji.

According to Faithful Foxes, a site dedicated to educating prospective fox owners, a domesticated fennec fox's diet should 'reflect their natural wild diet.' This includes: 'High quality meat-rich dog food, wild canine food brands, cat food, meats, insects, mealworms, custom dietary mixtures, or any combination.

'And remember, if the ingredients don't have an actual meat listed as the first ingredient, don't buy it.'

First days: Jumanji was adopted by Sonia back in 2014 (pictured) when she claims she rescued him from a breeder

Current look: Images of Jumanji looking particularly thin have been posted online by many accusing her of abusing her pet

Backing up: Facebook user Alice also posted correspondence with animal rights activists who echoed concerns for the creature

Sonia has since been bombarded on her social media and YouTube pages by angry animal lovers accusing her of slowly killing her pet by forcing an 'unnatural' diet on him.

In response to the stream of hate coming her way, Sonia took to Facebook saying that Jumanji's concerning appearance is actually down to 'a skin allergy due to plant pollen,' adding that it affects him more during the spring and summer months.

She shared a number of photos of Jumanji before and after being put on his current vegan diet, saying that his food includes 'all the needed amino acids for a carnivore animal such as taurine and lysine.'

'Thank you for being concerned about his health on this subject. He is in good shape, his blood tests are fine, he’s healthy, playful and hasn’t shown any signs of malnutrition for around 3 years,' she wrote.

In another post she argued that feeding an animal a meat-based diet is in itself animal abuse since it comes from other dead creatures.

Standing up: Sonia has defended herself against the accusations, saying that feeding her pet a meat-based diet would in itself be animal abuse

Offering proof: Sonia tried to show that Jumanji's diet has little to do with his appearance by posting this photo from 2015, when he was still eating meat

Ups and downs: Sonia shared this post showing her pet before and after his diet changed

Telling her side: Sonia revealed that she is working on a YouTube video explaining Jumanji's story and proving that he is healthy, but hasn't announced when it will be released

'They use the word "abuse" to describe the act of feeding [it] food that no animal had to die for. Despite the obvious oxymoron, any other non-vegan alternative does involve abuse by default,' she said.

Sonia has also posted a pair of videos of Jumanji running her home to show that the animal is indeed healthy, but viewers have accused her of using videos of a different fox to make her point.

Under one of the videos, Sonia commented that she is planning to release a video containing proof that Jumanji is perfectly healthy and not malnourished, but hasn't said when the video will appear.

'I am preparing a video to explain everything, debunking all the lies that some people have spread about this whole situation, putting updated blood tests, explaining his story etc,' she said.