Nausea, acid reflux, and a lower quality diet can all be a culprit. All of these cause an increase in the saliva production in the mouth which leads to lip smacking. It is actually a common misconception that dogs such as boxers, great danes and bull mastiffs are supposed to have long ropey drool.

Why does my dog keep smacking her lips and yawning?

Your dog may be yawning and lip licking due to stress or anxiety; he may be feeling nervous or fearful. Please note that a dog that is feeling fearful and cornered may bite. Bloat can cause yawning, lip licking, retching and drooling. ... If you suspect bloat, please take your dog the veterinarian as soon as possible.

Why is my dog smacking his lips at night?

A common reason that may cause a dog to excessively lick himself is allergies. Allergies cause a dog to feel itchy and he will excessively groom to try to alleviate the itch. Dogs may also lick their lips or objects obsessively if they are nervous, stressed, or bored.