COPULATORY TIE IN DOG

I was fortunate to see two dogs on my way back from football field today. Though this is not my first time of seeing dog sticking together

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The dogs were stucked together during the process of mating and I made my research about what could have been the reason for this incident.
Below are the images I took;

I found out that the process is called copulatory tie and research let me understand that;

“When a male dog emits semen, the 'bulbas glandis' of his genitals become quite stiff and at the same time the muscles of the vagina of a female dog become constricted. As a result, the male dog cannot remove its genitals from the female dog's genitals until both muscles are relaxed”
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