Your dog may know exactly where to toilet and still find a new place or a close lead hard. A trip away from the fenced yard changes the surface, smells, privacy and how much room they have to move. Do not solve that by letting a dog with unreliable recall off lead in an unsafe place.

First check whether this is a health problem

If your dog strains without passing stool, seems painful, vomits, stops eating or is acting unwell, contact your veterinarian promptly. If they seem acutely ill or cannot pass stool despite repeated painful attempts, seek urgent care. Tell the clinic how long it has been since a normal bowel movement. Do not keep waiting through another outing just to prove they can go on a lead, and do not give a home laxative without veterinary advice.

For a well dog who still toilets normally in the yard, practise in that familiar place first. Clip on a comfortable lead and give room to sniff and choose a spot while you stay quiet. Reward after they finish, not by leaning over or interrupting them. Later, try another quiet, permitted place with familiar timing and enough time to explore. Keep the lead secure and avoid tension that pulls them off the spot. If the change of place brings worry, make the next outing easier.

The slow sniff-walk guide has more on letting a dog explore safely on lead. It is an enrichment resource, not treatment for constipation.

Today, note your dog's usual toilet times and plan one calm, leashed opportunity in the secure yard. Their health and safety matter more than completing a trip on schedule.

Sources: Dogs Trust on house and toilet training. VCA on constipation signs and veterinary treatment.