Page 412 - WSAVA2017
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An Urban Experience
beings, a nodding of the head can occur with lesions of the thalamus and one of the authors has seen this in a dog with a thalamic lesion. A ‘yes’ head tremor also may accompany midline cerebellar lesions. Full diagnostic workup (blood work, CSF analysis and imaging of the brain) is normal with the idiopathic condition. There is little information on the most appropriate treatment: although there may be a partial response to antiepileptic drugs, usually they are ineffective. Fortunately, these tremors rarely impact the animal’s quality of life.
Paroxysmal Dyskinesias - Paroxysmal dyskinesias are episodes of abnormal involuntary hyperkinetic movement or muscle tone. These events are distinguished from seizures by the presence of a normal consciousness, although an EEG would be necessary to definitively determine this. A movement disorder has been described in young Bichon Frise dogs with an extreme variability
of frequency and random occurrence. A rapid muscular contraction causes hyperflexion and or extension of an individual limb. The thoracolumbar spinal column can be affected by altered muscle tone during the event causing a kyphotic posture. A similar condition has also been described in young Boxer pups provoked by excitement causing abnormal facial, truncal and limb movements with sustained hyperflexion.
No successful treatment regimens have been described. It remains to be seen whether a genetic disorder confirms these as truly breed related disorders as documented below. Several drugs have been reported to cause similar dyskinesias and include phenobarbitone and propofol in dogs. These disorders are usually reversible with drug tapering or withdrawal.
(3) Syncope
During a syncopal event, the animal usually collapses into lateral recumbency. Stiffening of the limbs, opisthotonic posture, micturition, and vocalization are common,
but facial ‘spasms’, persistent tonic/clonic motion, defaecation, a prodromal aura, (postictal) dementia,
and neurologic deficits are not usually associated with cardiovascular syncope; however, profound hypotension or asystole can cause hypoxic ‘convulsive syncope’,
with seizure like activity or twitching. Convulsive syncopal episodes are preceded by loss of muscle tone; however, seizure activity caused by underlying neurologic disease is usually preceded by atypical limb or facial movement or staring spells before the loss of postural tone. ‘Presyncope’, where reduced brain perfusion,
or substrate delivery, is not severe enough to cause unconsciousness, may appear as transient ‘wobbliness’ or weakness, especially affecting the pelvic limbs.
(4) Narcolepsy / Cataplexy and Sleep Disorders
Narcolepsy is a disorder of sleep/wake control characterized by a tendency to fall asleep during the day, disturbed night-time sleep patterns and cataplexy.
Cataplexy refers to sudden loss of motor tone ranging in severity from a dropped jaw to complete collapse without loss of consciousness and it represents a disorder of rapid eye movement (REM) sleep. Narcolepsy has been reported in many canine breeds, including Doberman Pinscher, Labrador Retriever, Miniature Poodle, Beagle and Dachshund.
The predominant sign in dogs and cats is cataplexy
but excessive daytime sleepiness and fragmented sleep patterns have also been reported. Cataplexy is characterized by paroxysmal attacks of flaccid paralysis without loss of consciousness and may last up to 20 minutes, with a sudden return to normality. The event
is not accompanied by faecal or urinary incontinence, salivation or rigidity of muscle groups. The episodes, which may occur multiple times a day, are frequently induced by excitement such as eating or playing
and they can be reversed by verbal or tactile stimuli. Cataplexy has been recorded in puppies and adult dogs but usually begins in the first 6 months of life with the establishment of REM sleep.
R.E.M. sleep disorders - Normal sleep is divided into 2 stages called non-rapid eye movement, the first stage of sleep lasting 20 minutes and rapid eye movement (REM) sleep. During non REM sleep there is a decrease in body temperature, heart rate and respiratory rate and the animals are immobile but retain muscle tone. REM sleep lasts for about 15 minutes during which animals have an increase in body temperature, heart rate and respiratory rate coincident with the eye movements and atonia of the postural muscles. Normal movements seen during this phase can include twitching of the eyelids, face, larynx and paws with occasional rhythmic paddling of all four limbs and yelping.
(5) Compulsive Behavioural Disorders
In dogs and cats, behaviors such as ‘‘fly biting’ and tail chasing have commonly been considered symptomatic for seizure disorders, although treatment with anti- epileptic medications may not be successful. These abnormal behaviors in companion animals have also been considered homologous to the stereotypic behavior of livestock and zoo animals. Such behaviors share similarities with human obsessive compulsive disorder (OCD), and have been referred to as OCD or compulsive disorders (CD). Obsessive compulsive behaviors in people include repetitive behaviors, such as hand washing, rituals, checking, arranging / ordering, counting and hoarding, and are accompanied by intrusive thoughts, such as concern of contamination; concern for symmetry; fear of harm; aggressive, religious, or sexual thoughts; or pathologic doubt. Interestingly, the intrusive thoughts (obsessions) and the associated behaviors (compulsions) do not necessarily correspond.

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