Long-distance train travel with a dog in India - looking for advice

I’m relocating permanently to another city for work and need to bring my dog with me. Leaving her with family isn’t an option.

I’m considering train travel as my preferred option, with road travel as a backup. My dog is generally quiet during car rides but tends to salivate heavily, so I’m a bit concerned about a long journey.

Has anyone here travelled long distances with their dog by train? How was the experience, how difficult was it to get a First AC coupe, and what should I keep in mind while planning?

Any tips or experiences would be greatly appreciated.