This is the heroic moment a pregnant horse was rescued after slipping into a septic tank in Thailand.

The four-year-old mare named Saengdow had reportedly tripped and fallen into the sewage outside her yard in Tak province on August 15.

Video shows Saengdow craning her neck out of the tank's opening as volunteers tied a rope around her body while preparing to hoist her up.

They then pulled on her forelegs while another rescuer used a long piece of wood to crowbar her bottom upwards. However, they had difficulty due to the cramped space, and the animal's muck-slicked body.

Saengdow had also grown considerably heavy since she was already five months pregnant.

Her worried owner tapped her awake each time her head dropped, seemingly on the verge of collapse from exhaustion and stress.

After around an hour of pulling, the team finally managed to release poor Saengdaw from the septic tank. The fatigued animal could not even stand up after the ordeal, opting instead to rest on the ground.

Onlooker Tammatat Thachai said: 'The owner had just arrived home after traveling from Bangkok. He found that a water tap was broken and this whole house was flooded. He believes that the horse tripped over the tap and fell into the septic tank in the afternoon.

‘We were afraid something might happen to the horse and its pregnancy, but luckily Saengdow is well and healthy.'