Hore struck Bradley Davies from behind in New Zealand's 33-10 win at the Millennium Stadium.
Welsh lock Davies needed hospital treatment after being knocked unconscious by Hore in the opening minutes and disciplinary chiefs are expected to take stern action after the 34-year-old was cited by match commissioner Mike Rafter.
Davies could still feature against Australia at the weekend, despite suffering from severe concussion, but Howley gave a scathing assessment of Hore when asked about the incident.
"What Hore did has got no place on a rugby field, as far as I am concerned," he said. "It was an absolute disgrace. He has been cited, and I am sure it won't be taken too lightly.
"Situations and incidents like that have no place on the rugby field, and it had a huge impact on the game."
New Zealand coach Steve Hansen is preparing to lose Hore through suspension and has already called up Chiefs hooker Hika Elliot into the squad for Saturday's clash against England at Twickenham.
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