Imagine not being comfortable in your own skin. Literally. Your skin itches, burns, tingles. You have intermittent stabbing pains. Nothing seems to relieve it. Sometimes it’s so bad you just want to scream. It wakes you from sleep. It happens frequently throughout the day. You never know when, or how intensely, it will strike. You can never get away from it.
That is what it’s like for cats who suffer with feline hyperesthesia syndrome (FHS). They are miserable. Their skin visibly twitches and ripples, especially when you touch them. They often viciously attack themselves: biting, scratching, rolling, throwing their bodies around, and even bolting like they’re trying to get away from themselves. They can become irritable, even aggressive.
Hyperesthesia means excessive sensitivity, especially of the skin. The term syndrome refers to the fact that the cause for the symptoms is unknown, as is the case with FHS. It can happen in any cat, but it is more common in Siamese, Burmese, Persian, and Abyssinian cats. FHS typically strikes between 1 and 5 years of age.
“My opinion is that this is not one disorder, but a similar manifestation of a number of possible disorders,” says veterinary neurologist Curtis W. Dewey, DVM, Diplomate ACVIM (Neurology), Diplomate ACVS.
There are four broad categories of potential underlying conditions that must be considered when faced with FHS: dermatologic (skin), musculoskeletal, behavioral, and neurologic (nervous system).
Considering a dermatologic problem makes sense, as FHS affects the skin. Your veterinarian should rule out all dermatological possibilities including fleas, flea-allergy dermatitis, food allergy, inhaled allergies (atopy), parasitic skin infections like mange mites and lice, and infectious skin disease like bacterial infection (pyoderma) and fungal infection (ringworm).
Musculoskeletal injury to the pelvic region and tail sometimes causes FHS-like symptoms. Muscular disorders are uncommon in cats but could cause symptoms associated with FHS. Diagnosing these disorders requires electromyography (a test that measures electrical activity in the muscles) and/or biopsy. This is often a last step, after all other potential causes and treatments have been exhausted.
Behaviorally, FHS may be a compulsive disorder that results in self injury. It’s thought that a complex interplay between neurotransmitters like dopamine and serotonin set off the neuromotor activity that results in symptoms of FHS.
Medications used to treat behavioral FHS include selective serotonin reuptake inhibitors (SSRIs) like fluoxetine (Prozac), tricyclic antidepressants (TCAs) like clomipramine, and benzodiazepines like alprazolam or lorazepam.
A neurologic problem is frequently considered once other causes have been ruled out.
“My impression is that many, if not most, FHS patients are experiencing a paresthesia (an odd sensation like itchiness) and/or hyperesthesia (a painful sensation) that has a neuropathic component,” says Dr. Dewey.
“The diagnosis of FHS is typically based upon history, signalment (gender, breed, age), and clinical features consistent with the disorder,” says Dr. Dewey. “There is no specific test for FHS, but depending on the particulars of each case, diagnostics may be indicated to find a specific cause for the irritability observed (e.g., a disk protrusion that may require MRI to diagnose). In most suspected cases of FHS, diagnostic tests are normal. I often base a diagnosis of FHS on typical features of the disease and treatment response.”
“My drug of choice for the initial treatment of FHS is pregabalin (Lyrica, a human nerve-pain drug used to treat fibromyalgia),” says Dr. Dewey. He says that pregabalin has demonstrated efficacy for both neuropathic pain and seizures (another potential cause of FHS). In Dr. Dewey’s experience, gabapentin, a common pain reliever, has similar effects but is less potent and its effects don’t last as long as pregabalin.
Dr. Dewey has also had success using electroacupuncture in FHS-affected cats.
“The prognosis for FHS is variable and at least guarded, according to the sparse amount of literature (nearly all of which is anecdotal) available on the subject,” says Dr. Dewey. “My experience is that most cats exhibit a positive response to treatment, although this may require several drugs in some patients.” He said that one published study found clinical improvement in six out of seven cats with FHS, with five achieving complete remission.
FHS is not common, but if it happens to your cat, it can be devastating. It’s uncomfortable for your cat and emotionally disturbing for both of you. Diagnosis and treatment start with your regular veterinarian, but referral for specialty care, whether it be dermatology, neurology, or behavior, may be necessary for this unusual disorder.