Feline hyperesthesia syndrome (FHS) is an enigmatic and controversial behavioral and medical condition that most often affects Oriental cat breeds. I saw my first case many years ago in a Siamese cat that displayed the three cardinal signs: excessive skin rippling or twitching (hence the alternative designation “rolling skin disease”), bouts of manic self-grooming, often initiated by stroking the cat along its back (”hyperesthesia”), and widely dilated pupils during bouts of the behavior.
The cat had just bitten one of our students, who was trying to restrain him, sending the student to the hospital for intravenous antibiotic treatment. Mercurial aggression, while being restrained, is another feature of FHS in some cats.
Other odd behaviors associated with the syndrome include periods of freezing in position while staring vacuously into space, sudden bouts of running away from what appears to be some unseen enemy and apparent hallucinations (visually following things that aren’t there).
In the early days, feline hyperesthesia syndrome was described as a compulsive disorder or stereotypy, but over time I became skeptical of the label to the point where I now consider it incorrect. The first seeds of doubt regarding the compulsive disorder etiology of FHS were planted by two long-in-the-tooth veterinary practitioners attending a talk I gave 20 years ago at a Arizona/California/Nevada veterinary meeting.
During question time, both senior veterinarians reported witnessing cats in the throes of an FHS bout transition into a full-blown tonoclonic seizure. Some weeks later in my clinic I saw a cat under treatment for tonoclonic seizures with phenobarbital also display signs of FHS.
At the very least, I thought, these two conditions were somehow linked and appeared co-morbid. The final straw came when I read an article by the late Dr. Barbara Stein in which she described various forms of feline hyperesthesia syndrome, ranging from frenetic self-grooming directed along the spine, tail chasing or tail biting, bizarre hallucinatory behavior, and any or all of the above, progressing to frank tonoclonic seizures. In other words, she, too, thought the condition manifested itself in various ways and that seizures were a component.
For years, I considered FHS to be a condition that somehow straddled the compulsive disorder-epilepsy spectrum and found that treatments for compulsive disorder, serotonin-enhancing drugs, like fluoxetine, and anti-convulsants, like phenobarbital and Keppra, were variously effective. Sometimes combinations of serotonin drugs and anti-convulsants worked when neither drug alone was sufficiently effective. There does not seem to be much rhyme or reason to why the treatment response is so variable.
In the midst of my dilemma, I read an abstract from the Ohio State University veterinary school in which researchers attributed FHS to a viral infection affecting cats’ epaxial musculature but have since written off that explanation as not gelling with the facts as we know them: For example, the fact that the condition affects primarily Oriental cat breeds and responds to selective serotonin reuptake inhibitors and anti-convulsants.
Another suggestion as to the etiology of this strange syndrome was made by an M.D. in the front row of a talk to cat owners I was giving at Tufts. After I had shown videotape of a cat with FHS who was apparently hallucinating, the doctor asked whether I had tried treating such cases with human antipsychotic medication because people who see or hear things that are not there are typically schizophrenics.
Looking at FHS from the prospective of it being a feline form of schizophrenia is so intriguing that the then-editor of the journal “CNS Spectrums” asked me to write an article on the topic. I declined because I wasn’t sure I had my all my ducks in a row, but here’s how I would have compared the two conditions:
Like schizophrenia, feline hyperesthesia syndrome affects males and females equally and usually begins in early adult life. Cats with FHS sometimes appear irritable or tense and, as mentioned, sometimes display explosive aggression, as do schizophrenics. The explosive aggression seems to occur when cats, like their human counterparts, falsely construe that others are trying to harm them.
This could equate with paranoia. Cats with FHS often show bizarre behaviors, ranging from occasional lack of activity (freezing) to apparent hallucinatory behavior. Genetic factors appear to play a role.
Schizophrenics also display bizarre behaviors, sometimes showing a lack of activity. They may experience visual or auditory hallucinations, and genetic factors seem to be involved in the condition.
In addition, an association exists between schizophrenic disorders and epilepsy, with seizures originating in the temporal limbic system. This type of association in cats with FHS would account for the strange compulsive-seizure spectrum that seems to encompass this entire syndrome.
Another similarity between FHS and schizophrenia is the medicines that are effective for treatment. For example, it is not unusual for schizophrenics to be treated with antidepressants of the selective serotonin reuptake inhibitor type, like fluoxetine (Prozac) and sertraline (Zoloft). Anti-convulsant medicines are also sometimes used to keep schizophrenics’ moods stable and reduce symptoms of the condition as well as any associated seizures.
It is logical to think that antipsychotic medications like risperidone may be effective and that there may be a place for anti-anxiety medications such as clonazepam (Klonopin) or alprazolam (Xanax).
I may not have convinced you that FHS is an animal version of schizophrenia, but you must admit the analogy is fascinating. I suppose FHS could be some unique idiosyncratic feline disease of neurological origin, but most behavioral conditions we see in animals have parallels in other species, including humans. It would be really odd if FHS occurred only in cats and had no other animal equivalent, but I suppose that is possible.
One final thought: Some schizophrenics inflict deliberate self-harm, injuring themselves quite seriously, and the same happens in extreme cases of FHS. In such cases, extreme self-grooming may progress to self-biting, particularly of the tip of the tail, and the injuries sometimes necessitate partial amputation of the tail.
One thing is for sure: FHS does occur, has the manifestations I described and is often successfully treated using SSRI’s or anti-convulsants. I must admit, though, that the jury is out on the precise cause of this bizarre and enigmatic behavior.
An author and researcher, Dr. Dodman is a professor at Cummings School of Veterinary Medicine at Tufts University and is founder of Tufts’ Animal Behavior Clinic.