Veterinarians and conservationists are worried about the deteriorating health of the last male northern white rhinoceros in the world.
The health of the rhino named Sudan is said to have significantly deteriorated after it developed a secondary and much deeper infection on his back right leg, beneath an initial one.
Sudan is one of only three living northern white rhinoceroses in the world. He lives at the Ol Pejeta Conservancy in Laikipia, Kenya.
According to conservationists at the Ol Pejeta ranch, the infection was treated but it is taking longer to heal.
"At the end of 2017, Sudan developed an uncomfortable age-related infection on his back right leg. It was immediately assessed by a team of vets from around the world and responded well to treatment, healing quickly.
"He resumed normal movement and foraging habits over January up to mid-February, with his demeanour and general activity improving significantly," read a press statement sent to newsrooms on Thursday morning.
Last year, the conservancy enrolled Sudan on Tinder, a dating app, in a bid to raise money for a northern white rhino breeding campaign.
Tinder users in 190 countries can access Sudan's profile in 40 languages. The app describes him as the "most eligible bachelor in the world".
If users swipe right (typically a sign of interest on the app) they will be directed to a campaign page to raise $9 million (Sh900 million) to develop reproductive technologies for the species, including in-vitro fertilisation (IVF), where fertilisation is done by manually combining an egg and sperm in a laboratory dish to form an embryo, which is then transferred to the uterus.
This, for researchers, seems to be the most viable way for conception since, like Sudan, the two surviving female rhinos are unable to breed naturally.
Age, they think, is a huge factor since female rhinos start breeding from age six or seven.
And Sudan is now 45 years.
"We are very concerned about him - he's extremely old for a rhino and we do not want him to suffer unnecessarily," added the statement.
Sudan's guards and keepers have watched him creep toward senility, trying not to think about what lies ahead.
Suni, one of the last three remaining northern white males, died in October 2014 at the age of 34. A few months later, the other northern white male died in the American city of San Diego.
For IVF to be performed, female gametes (ova or egg cells) have to be collected from the animals.