Jai Arrow's former Broncos teammate Sam Thaiday says watching his interview with 9News, in which Arrow showed clear decline, "hurt his heart".

The veteran forward played 178 NRL games including a grand final for the Rabbitohs, as well as 12 State of Origin matches for Queensland.

South Sydney's Jai Arrow speaks with Nine's Danika Mason after receiving a diagnosis for motor neurone disease.

In his first interview since his retirement due to a motor neurone disease diagnosis, Arrow showed clear signs of decline, particularly his speech.

Jai Arrow sat down with Danika Mason to discuss his diagnosis and what the future looks like.

Jai Arrow's former Broncos teammate Sam Thaiday says watching his interview with 9News, in which Arrow showed clear decline, "hurt his heart".