Yes, most dogs perform perfectly okay in water without the aid of a life jacket. But with some dogs, it’s a risk for the reasons stated. If your dog is overweight then a life jacket could be multi-purposed.
First, he is safe when he is in the water if he gets too tired, and also by using it and 
encouraging him to go into the water, you are giving him a safe workout to get him back in prime condition.
Where to get them
One disadvantage of shopping online is simply that getting the fit right for your dog is important and you cannot be sure of getting the right fit so you may have to send it back and get a better size. For this reason, it may be better to go to the pet supply store yourself with your dog. Having the wrong size delivered may be an inconvenience but still, online is the best way to see the variety and many dog life jackets would be adjustable anyway so possibly only a small concern.
A good place to look for bargains is on Amazon. There is quite a range available there. PetStreetmall.com, the Dog Life Jacket.com, the Big Dog Clothing, and eDogLifeJacket.com are just a few sites to check out.
The need for one
How often have you seen a dog on a boat whether out with fishermen or with the family? A dog life jacket is a must as if you are out in choppy waters, you cannot be too sure you will be able to rescue your dog if he ends up in the water. At least by equipping him with a dog life jacket, you know he will at least stay afloat until you are able to get him back onto the boat.
Sometimes in a lake, dogs excitedly jump into the water and then try to climb out in another location only to find a muddy bank and not able to get out. In trying, they are at risk of exhaustion. And you may be over the other side of the lake yourself and unable to get to them. It is always best to put the dog’s safety first and invest in a dog life jacket.
The choices and the styles, mostly practical but some are fancy; all sizes are catered for even teacup dogs although you may have to search a little harder.
It’s a question which all of us at first must answer. Dogs can swim so why the need for dog life jackets? Well, there are many circumstances where even the best dog swimmer can come a little unstuck in the water so it is not such a crazy idea to kit out your dog in a sensible and possibly life saving dog life jacket.
Take your time in selecting as there are many choices and ensure it is a comfortable fit. Some dogs may not enjoy wearing one and there is always the concern that he may damage it in trying to take it off so all the more reason to ensure that he is totally comfortable with it on.
Let your dog enjoy the water safely and get a dog life jacket.