Worst were her hip collapses, I assume a dislocation. Usually they would happen after a bit of running, but sometimes for no reason at all. She had to lie down and could not get up. These would correct after some minutes but she was in excruciating pain, and very wobbly for a while afterwards. The collapses had become more frequent. There are dogs with arthritis and hip problems, but the pain is at a lower level. I could not bear seeing her in this much pain and so the decision.

We had Cardhu since she was a tiny pup, over eight years. Not old, but not young either, about 60 in human terms. She was very intelligent, very good-natured. As a Border Collie, she had a strong herding instinct and loved to play a herding game with me. The herding instinct was very strong, and Cardhu attempted to herd our cat, something the cat did not like. A more interesting case came up when we had company for dinner and the guests had a toddler. Everyone was in the dining room, and the child was playing next to the dining room in the foyer – essentially a room with three sets of stairs. Every now and then the child would toddle toward a set of stairs so the mom would get up and move him to the centre of the foyer. After this happened two or three times, Cardhu realized this was a herding job and kept the child in the centre of the foyer. No growling or biting, just a bit of positioning and body language. The mom saw what was going on and allowed Cardhu to do the job.

For several years, Cardhu would to play in some of the parks with her many dog friends. It was a good-natured bit of energetic chasing and herding that would regularly last for well over an hour. I have seen Cardhu exhaust three dogs and then wonder why no one wants to play. We would also bicycle around the neighbourhood, with Cardhu running eagerly beside the bike. Ten kilometres (six miles) was a pleasant trot.

Border Collies have a very strong work instinct. One day Lynn was pruning in the back yard, cutting off branches then dragging them to the side gate ready for bundling. Cardhu watched for a few minutes, realized what Lynn was doing, then started helping by grabbing limbs in her teeth and dragging them to the gate.

We did agility, running obstacle courses. This is an activity at which Border Collies excel, as it needs speed, strength and obedience. As Carchu’s hip started to act up, I withdrew from this activity. A year or two ago, we were at a display, and I tried to get Cardhu to go up the A-frame (two pieces of plywood in the form of an A, the peak is about six feet high), and where she used to sprint up and down, now she was unable to get even half way up. As an obedient dog, there was no problem walking her off leash: one neighbour commented she had a virtual leash. All the neighbours knew Cardhu and particularly the children – mobs of them would crowd around to pet her.

At Susan’s suggestion, the day before taking Cardhu in, we had a steak dinner which we all shared (though on different plates!). Behaviour: when I placed some pieces of steak on Cardhu’s plate she looked at them and waited until I said, "OK."

Most difficult decisions are situations forced on people by external circumstances: there is no choice. This was probably the hardest decision I have ever had to make. Cardhu was a wonderful dog in so many ways, loved by everyone in the family. Having Cardhu put down was the right decision, but – especially for me - a truly sad one. I’ll miss her a lot.

"That'll do, Cardhu."