ABSTRACT OF THE WEEK

Journal of veterinary behavior : clinical applications and research
Volume 41 | Issue 0 (Jan-Feb 2021)

Hypersexuality responsive to phenobarbital in a male neutered domestic shorthair cat

J Vet Behav. Jan-Feb 2021;41(0):7-11. 43 Refs

Theophanes Liatis¹, Giunio Bruto Cherubini

¹ Dick White Referrals, Six Mile Bottom, Cambridgeshire,; Small Animal Hospital, University of Glasgow, Garscube Estate, 464 Bearsden Road, Glasgow, G61 1QH, UK. theofanis.liatis@gmail.com

Author Abstract

A 6-year-old, vaccinated, male neutered domestic shorthair cat was presented due to polyphagia and hypersexuality manifested since he had been adopted one year prior. Clinical and neurological examination was unremarkable, including absence of scrotal testicles and penile spines, indicative of testosterone absence. Differential diagnoses included inadequate neutering and residual testicular tissue, cryptorchidism, adrenal hyperplasia/neoplasia (sex steroid–producing), urinary bladder neoplasia, infectious myelopathy/neuropathy (e.g., feline infectious peritonitis [FIP]), temporal lobe epilepsy, or primary behavioral disorder. Hematology, biochemistry, and thyroid profile were almost unremarkable. Serology for Feline Immunodeficiency Virus, Feline Leukemia Virus, and Feline Coronavirus was negative. Serum pre- and post-human chorionic gonadotropin hormone stimulation Serum pre- and post-human chorionic gonadotropin hormone (hCG) stimulation testosterone ruled out cryptorchidism. Abdominal ultrasound revealed mildly enlarged colonic lymph nodes, the cytology of which revealed mild reactive hyperplasia. Urinalysis and culture were positive to Enterococcus spp. Magnetic resonance imaging of the brain and spinal cord and cerebrospinal fluid analysis was unremarkable. polymerase chain reaction in the cerebrospinal fluid for Toxoplasma gondii, FPV, FCoV, and bornavirus was negative. Attempts to treat hypersexuality as a behavioral disorder, urinary tract infection (amoxicillin clavulanic acid), pain (meloxicam and diazepam), and anxiety (diazepam) were unsuccessful. Thus, phenobarbital was prescribed in a low dose (1 mg/kg PO q 12h) which eliminated the episodes of polyphagia and hypersexuality without sedating the cat. Phenobarbital withdrawal resulted in hypersexuality re-establishment. Two years later, the cat remained episode-free on phenobarbital. Hypersexuality in male cats is characterized mainly by biting the nape, mounting, pelvic thrusting, penile erection, coital intermission, ejaculation, and/or masturbation. Temporal limbic structures play a significant role in the regulation of sexual arousal independently of testosterone. Hypersexuality has been associated with temporal lobe epilepsy in cats experimentally, while along with other clinical signs such as polyphagia, it is an established condition in humans called Klüver-Bucy syndrome. This is the first report to describe phenobarbital as a successful treatment of hypersexuality and polyphagia in a male neutered cat, raising a suspicion of feline Klüver-Bucy syndrome and temporal lobe epilepsy origin of these signs.

Companion Notes

Case report of hypersexuality responsive to phenobarbital in a neutered male cat

Introduction on hypersexuality

- hypersexuality = extremely frequent or suddenly increased libido

- nymphomania in women or satyriasis in men

- hypersexuality in male cats is characterized mainly by the following:

- biting the nape

- mounting

- pelvic thrusting

- penile erection

- coital intermission

- ejaculation

- masturbation

- temporal limbic structures significantly affect the regulation of sexual arousal

- and does so independently of testosterone

- in feline medicine

- penile spines indicate the presence of testosterone in male cats

- start to appear ~ 12 weeks of age and reach full size in the adult

- regress by 6 weeks after postpubertal castration

- single resting testosterone is not a reliable indicator of testicular dysfunction

- secretion is episodic and pulsatile

- stimulation by human chorionic gonadotropin or GnRH is more reliable

- urine spraying should not be confused with pollakiuria

(pollakiuria = increased frequency of urination)

- ~ 10% of neutered cats retain behaviors associated with intact tomcats

- mating may be present after castration

- hypersexuality has been misinterpreted in some intact sex:M cats

- cats showed persistent mounting with intense, prolonged pelvic thrusting

- without intromission

- thought due to formation of a hair ring around the base of glans penis

- penile spines may collect hair from perineum of sex:F cat

- in other tomcats, it might be due to improper pelvic orientation

- usually from lack of experience

- Klüver-Bucy syndrome (KBS) in human medicine

- hypersexuality reported in monkeys after bilateral temporal lobectomy

- usually consists of 3 or more of the clinical features below:

- hypersexuality

- hyperorality or marked oral examination of objects

- licking, sucking, chewing movements

- placing nonfood objects in mouth

- placidity (loss of fear response)

- hypermetamorphosis (compulsory urge to respond to visual objects)

- dietary changes including polyphagia, pica, and coprophagia

- visual agnosia (eg prosopagnosia)

[agnosia = inability to recognize sensory stimuli]

- hypersexuality in humans may include the following:

- ictal or postictal improper sexually oriented remarks

- exhibitionism

- attempts to touch the genitals of others

- solicitation of sex

- masturbation

- attempting sex with inanimate objects

- the following reported in humans with temporal lobe epilepsy

- interictal hyposexuality

- interictal transvestism

- exhibitionism

- fetishism

- most common clinical features in both affected adults and children with KBS

- hypersexuality

- polyphagia/hyperorality (most authors can’t distinguish between the two)

- causes of hypersexuality or Klüver-Bucy syndrome include the following:

- acute bitemporal injury or dysfunction

- bilateral temporal lobectomy or amygdalectomy

- traumatic brain injury

- meningoencephalitis, particularly herpes simplex encephalitis

- transtentorial herniation

- cerebrovascular disease

- postirradiation encephalopathy, especially after nasopharyngeal carcinoma

- metabolic disorders

- anoxic-ischemic encephalopathy

- carbon monoxide poisoning

- rapid correction of hyponatremia

- prolonged and severe hypoglycemia

- demyelinating disorders

- acute disseminated encephalomyelitis

- multiple sclerosis

- osmotic demyelination syndrome

- delayed postanoxic leukoencephalopathy

- methotrexate leukoencephalopathy)

- epileptic disorders

- ictal and postictal and complex partial (psychomotor) status epilepticus

- neoplasms

- developmental/congenital like bilateral arachnoid cysts

- progressive neurodegenerative conditions

- frontotemporal dementia

- Pick disease

- progressive subcortical gliosis

- other chromosome-17-linked dementias

- Alzheimer’s disease

- Huntington’s chorea

- amyotrophic lateral sclerosis

- adrenoleukodystrophy

- acute intermittent porphyria

- neuronal ceroid lipofuscinosis

- Sanfilippo syndrome (mucopolysaccharidosis III)

- Rett syndrome

Case report of a 6-year-old, vaccinated, neutered male DSHcat

- presentation for polyphagia and hypersexuality episodes since adoption 1 year prior

- hypersexuality episodes were reported to include the following:

- humping or biting the nape of the following:

- animate objects, owners and other household cats

- inanimate objects, towels

- followed by pelvic thrusting and penile licking

- no ejaculation noticed

- occurring 20 times/day with a duration of 2-3 minutes each

- physical examination and neurological examination: unremarkable

- absent scrotal testicles and penile spines

- differential diagnosis for a neutered male cat with hypersexuality

- inadequate neutering and residual testicular tissue

- cryptorchidism

- adrenal hyperplasia/neoplasia (sex steroid-producing)

- urinary bladder neoplasia

- infectious myelopathy/neuropathy (feline infectious peritonitis)

- temporal lobe epilepsy

- primary behavioral disorder

- differential diagnosis for polyphagia in cats

- primary polyphagia (CNS disease affecting the satiety center)

- psychogenic

- stress

- introduction of more palatable diet

- secondary polyphagia

- endocrine diseases

- exocrine pancreatic insufficiency

- parasitism

- neoplasia

- portosystemic shunts

- medications

- others

- CBC, serum biochemistry and total thyroxine: unremarkable

- negative serology for FeLV, FIV and feline coronavirus

- elevated alpha 1-acid glycoprotein (AGP) at 1004 µg/ml with reference at <500

- low serum resting testosterone at <0.3 nmol/L with reference at 0-7.6 nmol/L

- low testosterone post-human chorionic gonadotropin stimulation at <0.3 nmol/L

- with reference at 17.3-41.6

- suggesting cryptorchidism not present

- abdominal ultrasonography: lymphadenomegaly, colonic lymph nodes

- cytology: compatible with mild reactive hyperplasia

- urinalysis and urine culture: urinary tract infection by Enterococcus spp

- MRI of brain and spinal cord to investigate possible neurologic origin: unremarkable

- CSF analysis: unremarkable

- negative PCR of CSF for T gondii, FPV, FCoV, and Borna disease virus

- initial therapy for 2 weeks did not improve hypersexuality/polyphagia

- amoxicillin/clavulanic acid, 20 mg/kg PO q12h

- meloxicam, 0.1 mg/kg PO q24h for analgesia

- diazepam, 0.3 mg/kg PO q8h as a bladder relaxant/anxiolytic

- treatment

- environmental changes did not improve behavior

- provide extra space, privacy, entertainment (toys) and additional litter trays

- pheromone diffuser

- phenobarbital, 1 mg/kg PO q24h for 2 weeks

(antiepileptic effect or sedative effect might have affected the hypersexuality)

- episode frequency reduced to 10 per day

- phenobarbital changed to 1 mg/kg PO q12h

- episodes stopped for a month

- phenobarbital gradually withdrawn and stopped

- episodes returned to initial frequency of 20 per day

- phenobarbital, 1 mg/kg PO q12h reintroduced

- hypersexuality/polyphagia episodes stopped

- 1 month after phenobarbital reintroduction

- low serum therapeutic phenobarbital levels at 11 mg/l with reference at 15-30

- outcome at time of writing

- cat episode-free for a total of 2 years

- no reported adverse effects including sedation

“It should be noted that catamenian seizures should not be confused with KBS. It is known that sexual hormones might play a role in epileptic activity. Catamenian seizures are described as a pattern of seizures that changes in severity (e.g., clusters) during particular phases of the human menstrual cycle, wherein estrogens are proconvulsant, increasing the neuronal excitability, and progesterone is anticonvulsant, enhancing GABA-mediated inhibition…”

Keywords

feline, Klüver-Bucy syndrome, limbic seizures, polyphagia, temporal lobe epilepsy, phenobarbitone

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