My motto is, you can teach an old dog new tricks, but it can take more perseverance.
The fact that you have gradually become more strict assists this; as he has a general sense of your changing expectations, as opposed to be letting to run riot and then wanting a complete change (which would be confusing).
A good start, to give you some more instant relief, not as a long term solution, so you can enjoy your dog, is to drive the family to an off leash area and start your walk from there. Let your dog off leash and he dog can have a good sniff around. You will see when his initial enthusiasm wanes and that's your key that he is ready for a more manageable walk. It obviously means you and your family are stuck hanging around the dog park for 20 minutes or so, but it can be fun and interesting to chat to other dog owners (note I am assuming he is well socialised).
The gentle approach:
Not knowing your dog (I suspect you've already done this), it's important to try the easier softer way first.
when the dog attempts to go to a tree to sniff, a simple call;
Rover! in a high pitched voice (not a corrective tone, but a
hey look at this type of voice) may be all that is needed to bring his attention back to the walk. Remember to praise
if he is more reluctant and it takes more effort to get his attention, you can add the occasional food reward.
Now if this doesn't work, it's time for the hard part.
I would consider using similar techniques as for a dog pulling on the lead, as in effect, that is what he is doing, by going his own way on a walk and setting the pace.
Walk at a brisk pace, and encourage him with your voice. When he does this and he is walking on track, especially he he is looking at you, it can be a good idea to reward him with one of his favorite food treats; it is important to accompany this with plenty of verbal praise, as you want him to associate the verbal praise with the the anticipation of a food reward.
When using verbal praise dogs respond better to the same phrases used.
good boy! or
No!. I keep it really simple.
If he ignores you and insists on stopping to sniff; you can try:
- positive reinforcement
- you need to get your hand in his face, while using your voice; again with the tone of
hey look at this, you can have the treat in the hand you use to try and tantalise him, then reward him when he gives you his attention and continue the walk.
- as time progresses you can tease him playfully with the treat and prolong the time between his compliance and when you give him the treat. It can become a bit of a game between you both.
- as he progresses the rewards need to become randomized. After establishing a guaranteed reward expectation, you can move into partial reinforcement, which ultimately works very well. Even with well trained dogs, it's important to continue with partial reinforcement.
A word on punishment, for such a dear little dog of 12 years age, I would discourage using punishment, except for the harsh voice
The ASPCA has two articles:
Urban Dog Etiquette
The command “Leave it” is employed when it is necessary for Fido to avert his gaze. Whether he's being tantalized by chicken bones or a jogger, getting your dog to break eye contact with “forbidden fruit” before he acts enables you to draw his attention to safer rewards and pursuits. Or, should the dog slip his collar or break his leash, a recall command (“Come”) could save his life. Most, if not all, of these commands are taught in basic obedience/manners class. Contact your local shelter for a referral to a class near you.
Teaching Your Dog Not to Pull on a Leash
Teaching a dog to walk without pulling requires plenty of rewards. Use highly desirable treats that your dog doesn’t get at other times. Soft treats are best so your dog can eat them quickly and continue training. Most dogs love wieners, cheese, cooked chicken or ham, small jerky treats or freeze-dried liver. Chop all treats into small peanut-sized cubes.
Walk at a quick pace. If your dog trots or runs, she’ll have fewer opportunities to catch a whiff of something enticing, and she’ll be less inclined to stop and eliminate every few steps. Additionally, you are far more interesting to your dog when you move quickly