Dear Daisy Dog: Gertie, my 8-year-old cocker spaniel mix, looks odd. Her left ear and lip droop, and she drools out the left side of her mouth. What’s going on? Did she have a stroke? What should I do about it?

Daisy Responds: Since she’s developed a problem, Gertie should see her veterinarian. She may have facial nerve paralysis, an abnormality of the nerve that controls the muscles of facial expression.

The left and right facial nerves control the position of the ear, eyelid, cheek, lip and nose on their respective sides of the face. Partial or complete paralysis of one of these nerves leads to facial droop, drooling and diminished ability to blink. Since the muscles on the other side of the face usually have normal tone, the nose deviates in that direction.

Facial nerve paralysis most often targets middle-aged and older dogs. While the disease strikes both genders and all breeds of dogs, it’s most common in cocker spaniels.

In three of four affected dogs, a cause cannot be found, and the disease is termed idiopathic facial nerve paralysis. It’s similar to Bell’s palsy in humans.

In the remainder of dogs, causes include a middle or inner ear infection, inflammation along the nerve’s pathway, such as from head trauma or a bite wound, or any condition that affects the nervous system in general, such as hypothyroidism or hypoglycemia.

Treatment is aimed at resolving the underlying cause, if one is found, and addressing the clinical signs. For example, if Gertie can’t blink, artificial tears must be applied regularly so her eyes don’t dry out.

Idiopathic facial nerve paralysis completely or partially resolves in weeks to months. We wish her a full recovery.