Feline Hyperesthesia (FHS)

Ever since the earliest days of human-cat interactions, we’ve puzzled about the unique and confusing behavior of cats. Throughout history, this has often given them a reputation for being divine, mystical, or even possessed.

As devoted cat companions, we often ask ourselves which kitty quirks are normal, and which could signal a problem, like pain, stress, or illness. Nothing exemplifies the need to understand normal cat behavior more than the poorly understood medical condition, Feline Hyperesthesia Syndrome.

Clinical Signs of Feline Hyperesthesia Syndrome (FHS)

• Sudden bouts of bizarre hyperactive or aggressive behavior
• Frenetic self-directed grooming, directed along the flank or tail (possibly leading to hair loss)
• Tail swishing, fixation with tail, tail chasing, or vicious attacks directed toward the tail
• Large pupils/strange look to the eyes
• Skin rippling/rolling (this disorder is sometimes referred to as “Rolling Skin Disease”)
• Vocalization, crying, loud meowing
• Sensitivity to touch (“hyperesthesia”) along the spine – stroking can precipitate a bout of the behavior
• Sudden mood swings – e.g. from extremely affectionate to aggressive
• Seizure-like activity including falling, twitching, paddling, and salivation Clinical signs that are present constantly or intermittently.

Possible Causes

FHS tends to appear for the first time in mature cats. No one really knows what causes FHS, but there are a few possibilities:

• Because some cats display seizure-like signs during or following a bout of FHS, some experts suspect that the condition arises from aberrant electrical activity in areas of the brain that control emotions, grooming, and/or predatory behavior (i.e. there may be partial seizure activity). Some affected cats also seem to respond to anticonvulsant (anti-epileptic) therapy.
• FHS could be a form of feline obsessive-compulsive disorder (OCD) in which the obsession relates to grooming and/or aggression. The apparently compulsive nature of self-directed grooming and a positive response to behavior-modifying medication supports this etiology.
• Genetic factors. There may be an inherited tendency for stress to precipitate manic behaviors. Some breeds are more susceptible to FHS and stress does seem to trigger clinical signs.
• Some affected cats have been reported to have pathological lesions in the muscles along their spine. It is hypothesized that the lesions may cause local irritation, altered sensitivity, and/or pain.

Diagnosis

Many well-understood medical conditions can cause clinical signs that are similar or even identical to FHS. Because there is no definitive test that confirms FHS, it is important that veterinarians eliminate other possible causes for the cat’s unusual behavior. Conditions like parasites, hyperthyroidism, spinal cord injuries/disease, dermatological disease, and others must be investigated and ruled out. If the clinical picture fits FHS and no other illness has been identified, a positive response to treatment for FHS allows the condition to be diagnosed. To this end, your veterinarian will obtain a careful behavioral history regarding your cat, perform a thorough physical examination, run diagnostic blood and skin tests, and take spinal x-rays.

Treatment

Optimize the affected cat’s environment to minimize stress (stress could be a factor in every expression of the syndrome). Recommendations include:

• Provide daily aerobic exercise for the cat by playing with the cat using a feather wand toy or toys dragged along on a string.
• Feed the cat frequently and on a regular schedule to minimize stress over food.
• Provide mental stimulation by training the cat to perform one new trick each month (come for food, sit for food, jump up, jump down). Click and treat training is the best way to accomplish this goal.
• Address any infighting between existing cats in the home. Feed cats separately, and provide multiple litter options in different locations in the home.
• Arrange predatory play activities to allow the cat to “blow off steam” and dissipate any unvented prey drive. The feather wand type of toys mentioned above are appropriate for this purpose, as are “laser mice” toys, ping-pong balls kicked or dragged around, Cat Dancer toys, and so on.
• Make life interesting for your cat: spend more quality time with them and make the environment more “cat friendly.” Provide a three-dimensional environment by adding cat perches, and strategically place them so that they can sit up high and have a good view of the world. Buy a fish tank or get some birds in a cage, but make sure the little ones are always safe and secure. Get a window bird feeder. Provide an assortment of cat toys – moving interactive toys are best. Catnip mice appeal to some cats.

Behavior-Modifying Therapy

Drugs that help are potent serotonin-enhancing medications. In the brain, the neuromodulator, serotonin, stabilizes mood and has anti-obsessional and anti-aggressive effects. Drugs that have been found effective include clomipramine (Clomicalm®) and fluoxetine (Prozac®) Your vet may also recommend other potent serotonin-enhancing drugs, including paroxetine (Paxil®), sertraline (Zoloft®), and fluvoxamine (Luvox®). These drugs take a while to become effective. Typically, little to no improvement is seen for the first three weeks. Then, by four weeks, owners might notice a 50% reduction in the incidence and severity of bouts of FHS. Typically, the improvement may reach 75% at eight weeks, 85% at 12 weeks, and 95% by sixteen weeks.

Complete cure is rare and most cats need to remain on medication long term to suppress the FHS behavior. Pet owners can be assured that medical complications of treatment are rare, and the benefits of treating the condition generally outweigh the risks. Nevertheless, it is important for affected cats to be monitored regularly by the veterinarian, and complete appropriate bloodwork at least once per year. If you’re concerned about costs related to treatment of behavioral issues, pet insurance may be able to help. Click here to learn more.

Anti-Convulsant Therapy

When stress reduction and behavior modifying therapy is ineffective or only marginally effective, anti-convulsants can be administered. One common treatment choice is Gabapentin. Gabapentin has a multi-modal benefit of reducing stress in cats, addressing nerve-generated pain, and suppressing seizure activity. This medication is given by mouth, so it can be administered to cats at home. Unfortunately, many cats don’t like the taste of gabapentin, so it’s important to work with your veterinarian to find a flavor and texture option that works well for your pet.

Conclusion

With appropriate environmental and pharmacologic treatment, affected cats can often be rehabilitated and can lead a normal life. When treated, most appear much happier than they were previously while suffering the full brunt of their affliction.