black dog

Translations
черная собака
He has been struggling with the black dog for years.
Он борется с черной собакой уже много лет.
Definitions
A metaphor commonly used to describe feelings of depression or melancholy. The phrase 'black dog' was popularized by Winston Churchill to refer to his own struggles with depression.
Words
dog

noun
собака
black

adjective
чёрный