St. Bernard in Delhi, India

Hi, sounds like you have a gorgeous dog there Not quite sure what health issues your friend is refering to? You could possibly encounter behavioural problems with him around this age as it's usually around this time a dog will turn into an unruly teenager, but as long as you keep on top of his training and make sure he knows his place you should be OK and having him castrated will also help.
St. Bernards, like most large, heavy coated dogs do prefer colder climates. Do you have a cool area where he can go to escape the heat and is there anywhere he could swim or have a paddle around? Just be sure not to walk him during the hottest part of the day...maybe keep walking to a minimum until the evening when it's cooler. Be sure to carry plenty of water with you for him to drink and you could also carry a cloth that you can wet so you can wipe down his forelegs and ears which will also help to cool him. Be sure he always has access to fresh drinking water around the house as well.
If you are worried about him becoming bored and excitable when he can't be walked as often, then up the amount of time you spend playing with him as mental stimulation tires dogs out almost as much as walking them. Try playing games like hide and seek with a toy or treats...dogs like this have a tremendous sence of smell and love to have it put to the test.
ALso without sounding cheeky.....I can see the attraction with having a St. Bernard, we nearly did....but why did you get a breed that couldn't tolerate your climate???

Hi again, the damage to bones and joints can be minimised by limiting the amount of walking your dog does as a puppy, not letting him use stairs or jump etc. I own 2 large breed pups....although they look like adults now ...and have had to be very careful with regards to exercise. Were your dogs dam and sire hip scored and heart tested? If they were and found to be normal, this should mean there is less chance of your pup encountering genetically inherited problems with his hips and heart and you should just be as careful as possible with him till his growth slows down. Your vet will be able to check your dogs hips and heart at the relevant age if you are worried. Is the breeder of your dog based in India, they may be able to give you more advice on how to keep him cool?

Swimming is also good for helping build muscle around the joints and as it's a low impact exercise it won't do your dog any harm...don't know how easy it would be to find somewhere for your dog to swim in India and it depends if you dog likes the water too Does your vet have a hydrotherapy pool? Raw eggs are more for the dogs coat and if you are giving milk, try goat's rather than cow's as it contains less fat