My dog barks when tied up outside. Could it be separation anxiety?
It sounds like Onyx is having some separation anxiety. If he can see you, but can't get to you, he might not understand why he can't. Is there a reason he needs to be tied up? Are you able to just let him lose to spend time with you? If you can't keep an eye on him, keeping him in a pen or crate while you are gone may help him feel more comfortable in a sort of "den" rather than being tied up (and is safer). If you are home, having him stay by your side may help reduce his anxiety.
Looking up separation anxiety treatment online may also help give you some ideas on how to make him more comfortable, or you can speak with a local trainer that can observe the situation. If Onyx must be tied up, giving him a puzzle toy filled with a favorite treat may provide enough distraction to help him calm down.
Updated on September 23rd, 2025