Ganesh Joshi, a legislator from the northern state of Uttarakhand, was arrested after he allegedly beat the horse, named Shaktiman, with a stick, during a protest rally in the city of Dehradun.
However Mr Joshi, who was released on bail, has denied assaulting the animal.
Rakesh Nautiyal, the veterinary officer looking after Shaktiman, told the BBC that the horse was now standing and "improving day-by-day".
"The positive approach of the animal has amazed me. Even after undergoing a major surgery Shaktiman is displaying normal behaviour. He is eating well, which is a good sign," he said.
Next in line for the horse is a special shoe called an "ice boot" being brought in from the US, which will help the animal reduce weight on the amputated limb.
"Through the ice boot we will be able to take precautionary measures to keep the hind leg safe," a senior vet told the BBC.
The horse has become the centre of attention in Dehradun, where he is lodged at police quarters.
He is attended to by a team of vets and the police force is sparing no expense for his treatment, even though Shaktiman will never be able to resume official police duties.
At the forefront of efforts to rehabilitate Shaktiman is US animal lover Jamie Vaughn, who has made it her personal mission to care for the animal.
Fondly referred to as "chachi" (aunt) by the Dehradun police officers, Ms Vaughn, who runs an NGO called Maya Foundation for animal welfare in Bhutan, has used her extensive network of contacts to fund most of Shaktiman's post-operative care.
She has facilitated the construction of a new tin shed for the horse, which has been fitted out with two water-cooled fans, a mosquito net and fluorescent lamp. Shaktiman also gets a massage every day.
His bedding is changed every second day and the bandage is changed twice a week.
"I came to Dehradun to see Shaktiman after I received a call from the doctor who operated on him," she told the BBC.
"A lot of people are concerned about the horse and are providing help. The horse is adjusting to the new prosthetic leg. But the road to recovery is still long and needs patience."
An Indian police horse that had a leg amputated after being allegedly assaulted by a politician, has been fitted with a state-of-the-art prosthetic limb that is allowing the animal to stand again, Raju Gusain reports.