To be sad as a dog idiom? - briefly
"To be sad as a dog" is not a recognized idiom in English. The correct expression for someone who is deeply unhappy or depressed is "to be down in the dumps."
To be sad as a dog idiom? - in detail
The idiom "sad as a dog" is not commonly recognized in English and does not appear in standard dictionaries of idioms or proverbs. It seems that this phrase might be a misinterpretation or mistranslation from another language, or possibly a regional or local expression that has not gained widespread usage.
In English, there are several well-known idioms related to sadness, such as "feeling blue," "down in the dumps," or "glum." These phrases capture the essence of feeling sad or depressed and are widely understood and used in everyday conversation. However, "sad as a dog" does not fit into this lexicon of common English idioms.
If you encountered this phrase in a specific context, such as literature, poetry, or a particular region's dialect, it might hold a unique meaning within that framework. Without additional context, it is challenging to provide a precise definition or explain its usage effectively.
For accurate communication and understanding, it is essential to rely on widely recognized idioms and expressions. If you wish to convey the idea of sadness, consider using established phrases like "feeling blue" or "down in the dumps," which are universally understood by English speakers.