When dogs greet each other on lead, there are a few things happening:

1 – The lead limits options. A dog who is a little bit unsure or nervous will easily feel trapped and out of options on a lead, which can make them go on the defensive.

2 – Leads create body tension. When dogs are pulling at the end of the lead or the owners hold the lead tightly, this adds tension to the situation. Not only does tension make the dog feel more uneasy, but it also makes their body language more tense and unfriendly, which isn’t setting them up to get on well.

3 – The lead generates frustration. A dog who is excited to greet another dog will be easily frustrated at being held back by a lead and this can lead to them getting overexcited and overreacting.

4 – The dogs are forced to greet head-on. Usually on-lead greetings mean head-on greetings, which are unnatural and a bit confrontational. All of these factors together mean that on-lead greetings between dogs are usually fuelled with anxiety, overexcitement, and frustration.

It is possibly the worst possible scenario for having two dogs meet and should be avoided at all costs.