As you say the dog is a pet, she will need to travel in the hold unless you fly private. There is not a single airline flying this route allowing non-service dogs of this size in the passenger cabin. Getting her on as an ESAN could be an option, but one I will not be discussing or condoning here.

There's three ways of getting to India from Houston - either trans-atlantic with a stop in Europe (on AF, KLM, LH, TK) or the Middle East (on Qatar, on Emirates the dog will have to be flown as manifested cargo due to total flight length exceeding their 17-hour limit for AVIH acceptance), trans-pacific with a stop in Asia (on KE, OZ and others), or (somewhat) direct on Air Canada with a transfer in Vancouver or Toronto or United via Newark, but that's using PetSafe, which doesn't appear as safe as its name suggests and is several times as expensive (about $1,300 all in if dog and carrier stay under 100 lbs, $1,700 if above 100 lbs) as flying her as checked baggage. While Air India normally allow pets on their flights, they do not accept them on direct routes routes to/from the US, presumably because flight times are too long.
Personally, with an animal I would go via Europe to spare the dog the super-long transpacific fligths. Houston to Frankfurt (on LH), Paris (on AF) or Amsterdam (on KLM) is about nine-and-a-half hours (add 90 minutes of time in crate between check-in and retrieval at the oversize baggage carousel), followed by another seven-and-a-half hour long flight to Delhi. Much better than flying transpacific which will mean flight times of 14 hours and 16 hours of being in her crate.
I would take the one-stop itinerary rather than go IAH-BOS-FRA-DEL just to shave less an hour off the transatlantic flight time. That does not make sense. The stressful part of the journey is takeoff, landing and getting bounced about on carts, conveyor belts and baggage handlers in the airport - once up at cruising altitude, they just go to sleep in the darkness of the cargo hold.
I have taken dogs on intercontinental flights dozens of times with nary an issue, and generally avoid any itinerary where the animal would need to be in a crate for more than twelve hours without a break if possible.

Going one-stop via Europe, there is three choices of airlines, all of which are dog-friendly and have top facilities:
Lufthansa via Frankfurt ($400 pet fee)
Air France via Paris ($200 pet fee)
KLM via Amsterdam ($200 pet fee).
If you want to book a long layover or day-long stopover to give the animal a break, you can either pay for care in the airline facilities (around $150) or get the necessary paperwork to enter France/Germany/the Netherlands, retrieve her and take her on a European hike . Caveat: when booking the flights, make sure they're all native LH/AF/KL flights and not operated by UA or DL. Neither UA nor DL allow animals as checked baggage anymore.

Frankfurt is perfect for this, as the airport is surrounded by a forest with trails where you can let her run off-leash(!) to her hearts content. This is directly accessible from the airport. Quickest/most convenient way is to take the shuttle bus to the Steigenberger Airport hotel which is directly adjacent to the forest. If you want to stay the night, they're pet-friendly.
But that won't even be necessary. Booking LH 441 (IAH-FRA) to LH 760 (FRA-DEL) will give you a five-hour layover in Frankfurt - enough time for a two-hour forest run which will leave doggie nicely tired for the second part of her trip. I have taken many dogs from Europe to South America and vv via the US with a few hours of running on trails around Lake Grapevine during a DFW layover and by the time we had to go back to the airport to check in for the second leg of the flight they were totally ready for a few hours of napping in their crate.