assistance dog
US /əˈsɪs.təns dɔːɡ/
UK /əˈsɪs.təns dɔːɡ/

1.
a dog that has been specially trained to help a person with a disability
:
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An assistance dog can provide invaluable support to people with visual impairments.
•
The restaurant welcomed the customer and her assistance dog without hesitation.