Dog haven't got a huge sound vocabulary - its barking, growling, howling and whining and that's about it.
Here are some of the most common reasons why dogs whine.
1. They are seeking our attention - this is most common and tops the list of reasons.
2. Our dog may be uncomfortable. This could mean he/she is cold, wet or hot etc..
3. Dogs will whine if they are in pain.
4. It is common for a dog to whine if he/she is not comfortable in a new environment. Whining in a dog crate is a very common behavior.
5. The dog may be bored or lonely.
6. A dog who whines may need to go to the toilet (or has already soiled his sleeping area).
7. Dogs with unused energy will often whine - the energy has to come out somehow!
8. A hungry or thirsty dog will often cry or whine.
9. Many dogs whine because it works - we reward them for it!
10. The whining may be a symptom of canine separation anxiety.
11. If your dog is whining take a step back and consider whether he/she is involved in the family, loved and properly exercised?
Hope this helps answer your question

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