Buon Giorno - with a dog you are going to have to get a house. None of the apartment buildings or condominiums allow pets of any kind. Also none of the hotels or guest houses as far as I've been able to determine allow dogs. You will need to have housing sorted out before you bring your dog.
25,000 TB is 657 euro a month or approximately 800 USD. That's not a lot of money and will be a tight squeeze if you want anything resembling a western standard of living. You certainly will not be able to save anything.
We pay 14,000 bhat a month for a townhouse with a small yard. Electricity will run 900 to 1500 a month, we run the AC a LOT (and yes, we are high maintenance americans). Water is another 100 bhat. Satellite TV varies up to their most expensive package is 900 bhat. Internet is 2000 bhat, transportation is another 1000. That is 18,000 bhat not including cell phone.
Cars, gas and insurance is horribly expensive. On 25,000 a month you probably won't be able to afford one. If you try to bring one from Italy the customs will be equivalent to the original purchase price. Even 15 year old cars here sell for 200,000 bhat or more.
After fixed living expenses you have 8000 bhat a month for food, entertainment, travel which is doable but tight.
You would need to make sure your employer provides health insurance or you would be required to pay for all your medical care. It's not like Italy's national health care plan. The only people who qualify for national health care are thai nationals. As a farang they WILL dump you back on the street if you can't pay for care.
Make sure wherever you live you are within easy walking/bicycling distance of work, food markets, entertainment, etc.. You can find nice suburban homes out past the ring road but you will easily pay another 1000 bhat a WEEK for transportation. If you live within the ring road (the closer to the center the better) you can usually grab a songtaw anywhere in the ring road for 20 bhat. However, you may pay more for rent but it still is less expensive to live city center.
Motorcycles are an option if you want to have your own vehicle. Most thais (particularly the young people) ride motorcycles.
As far as bringing your fur baby we moved here with ours in November. He is a xoloitzquintli which is a Mexican Hairless so the heat is his friend. If you are talking about a breed of dog bred for northern climes (husky, malamute, german shepherd) they look pretty miserable. They will end up inside in the air conditioning.
You have to be extremely careful when walking your dog. Thais are notorious for poisoning the street dogs. Unfortunately your dog can ingest the same poison the same way.
Additionally the food offerings for Buddha when they sit out in the sun can develop various bacteria that can make a dog extremely sick. The offerings are left many times right on the ground where any dog worth the name of dog will immediately snap it up.
There have been stories of people throwing poisoned food over fences at neighbor dogs that are too noisy, etc. Thais are totally non-confrontational so they won't complain to you about your dog they will just remove the problem.
When you arrive take your dog to a vet and get a parvo, distemper immunization update. There is a version of distemper here in Asia that doesn't seem to be covered by European and American vaccines. I've been hearing about it from friends in the rescue community.
If you are only coming for a year or two I'd recommend you leave your fur baby with your parents, kids, friends or other relatives. Even a small dog (and mine is less than 4 kilograms) cost 250 euro as luggage.