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What is part of the CNS (central nervous system)?
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What is part of the peripheral nervous system?
- cranial nerves
- peripheral nerves
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What are the different CNS diseases?
- idiopathic epilepsy
- intervertebral disc disease
- atlantoaxial subluxation
- cervical spondylomyelopathy
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What is idiopathic epilepsy?
- convulsions, fits, spells
- repeated episodes of seizures
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When do idiopathic epilepsy usually occur?
seizures usually begin between 1 and 3 years of age
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What are the different stages of an idiopathic epilepsy?
- aura (pre-ictus)
- ictus
- post ictus
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What is the aura stage? How long does it last? What kind of behavior do we see during this stage?
- just before the seizure
- lasts minutes to hours
- abnormal behavior - pace, seek companionship, hide, bark, salivate
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What is the ictus stage? What are the signs of this stage?
- actual seizure event
- many forms exist - full body, focal, petit mal, behavioral
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What is the post-ictus stage? What are the signs of this stage?
- after the actual seizure
- disorientation, inappropriate bowel/bladder activity, increased thirst/appetite, weakness, blindness
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How do we diagnose idiopathic epilepsy?
- CBC
- serum profile
- UA
- radiographs
- CT scan
- MRI
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How do we treat idiopathic epilepsy?
- treat primary disease if present
- initiate treatment if more than 1 per month
- phenobarbital
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What is the realistic goal when treating idiopathic epilepsy?
to reduce the frequency, severity, and duration of the seizures
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How long does phenobarbital take to reach a steady state in the blood?
7 - 10 days
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What should we monitor when a patient is on phenobarbital?
serum levels
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What are some side effects of phenobarbital?
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What can we combine with phenobarbital to treat idiopathic epilepsy?
- potassium bromide
- felbamate
- valproic acid
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How do we educate clients on idiopathic epilepsy?
- no cure
- reduce frequency, severity, and duration
- spaying or neutering may help to prevent hormonal influences
- medication will probably be required for life
- check serum drug levels frequently
- rectal diazepam
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What is status epilepticus?
- continued seizures for prolonged periods of time
- more than 5 - 10 minutes
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Is status epilepticus a medical emergency?
yes due to hyperthermia and difficulty breathing
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What can status epilepticus cause?
irreversible coma or death
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Should we treat status epilepticus aggressively?
yes
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How do we treat status epilepticus?
- diazepam IV
- pentobarbital IV
- establish an ariway, oxygen as needed
- IV catheter
- monitor body temperature
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What does IVD stand for?
intervertebral disc disease
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What is the most common disorder involving the spinal cord?
IVD
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What is extrusion?
rupture of nucleus pulposus into vertebral canal
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What is protrusion?
disc bulges into vertebral canal
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What is IVD?
compression of the spinal cord
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Where can IVD occur?
- cervical
- caudal thoracic
- lumbar disc
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What is IVD usually secondary to?
degenerative changes in the disc
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Can a spinal cord injury cause IVD?
yes
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What are the clinical signs of IVD?
- pain
- muscle spasms
- reluctance to move
- lameness
- hunched up
- abdominal muscle rigidity
- ataxia
- loss of proprioception - the body's awareness of posture, position, movement, changes in balance
- paresis - partial paralysis, weakness
- paralysis
- loss of deep pain perception
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How do we diagnose IVD?
- plain radiography - accurate in 70% of cases
- myelography - more definitive location of lesion
- MRI - accurate in 85 - 97% of cases
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When do we treat IVD medically?
painful, no or mild neurological deficits
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How do we treat IVD medically?
- strict confinement, 2 - 3 weeks
- anti-inflammatory drugs
- analgesics
- urinary and fecal incontinence management
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When do we treat IVD surgically?
- substantial neurological deficits
- medical treatment failure
- recurrent episodes
- urinary and fecal incontinence mangement
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How do we educate clients on IVD?
- weight control, especially in predisposed breeds
- avoid back strain
- dogs treated medically only - recurrence rate is 40%
- lack of deep pain for more than 24 hours (poor prognosis)
- lack of deep pain for less than 24 hours (guarded prognosis)
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Which breeds are predisposed to IVD?
chondrodystrophic breeds - dachshunds, pekingese, lhasa apso
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What breeds do we typically see atlantoaxial subluxation in?
toy breeds - yorkshire terrier, miniature poodle, toy poodle, chihuahua, pekingese
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What age do we usually see atlantoaxial subluxation?
young dogs - under 1 yar old
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How does atlantoaxial subluxation occur?
- instability of the atlantoaxial joint
- C2 luxates dorsally
- compression of the spinal cord
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What are the clinical signs of atlantoaxial subluxation?
- reluctance to be patted on the head
- neck pain, low head carriage
- gait dysfunction
- tetraparesis, tetraplegia
- sudden death due to respiratory paralysis
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How do we diagnose atlantoaxial subluxation?
- radiographs - be careful not to cause further trauma when positioning the animal
- if animal is under general anesthesia for films, may need to splint neck
- must be very careful with neck during anesthetic recovery
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How do we treat atlantoaxial subluxation medically?
- splint neck in extension for 6 weeks
- anti-inflammatories
- analgesics
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Why do most cases of atlantoaxial subluxation treated surgically?
to relieve pressure on the spinal cord
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How do we surgically fix atlantoaxial subluxation?
immobilize joint
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What percent of surgeries for atlantoaxial subluxation are successful?
60%
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What is another name for cervical spondylomyelopathy?
wobbler syndrome
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What is cervical spondylomyelopathy?
- cervical vertebral malformation of misarticulation - C5 - 7
- compression of the spinal cord
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Which breeds are common for having cervical spondylomyelophathy?
- doberman pinschers
- great dane
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What age do we typically see clinical signs for cervical spondylomyelopathy?
seen by 1 - 2 years old
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What are the clinical signs of cervical spondylomyelopathy?
- ataxia of rear limbs, +/- fore limbs
- abnormal wear of dorsal surfaces of rear paws
- swinging, wobbling gait in rear
- proprioception deficits
- rigid flexion of neck
- neck pain is variable
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How do we diagnose cervical spondylomyelopathy?
- radiographs
- myelography, CT, or MRI to localize lesion
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How do we treat cervical spondylomyelopathy medically?
- restrict activity
- corticosteroids
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What does surgical treatment of cervical spondylomyelopathy do?
- decompresses spinal cord
- stablizes vertebral column
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What is the percent recovery for patients who have surgical treatment of cervical spondylomyelopathy?
40 - 80%
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What causes peripheral nervous system diseases?
- idiopathic vestibular disease
- neuropathies - metabolic - hypothyroid, diabetes mellitus
- laryngeal paralysis
- megaesophagus
- tick paralysis
- coonhound paralysis
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Which animals do we see idiopathic vestibular disease in?
- middle aged dogs
- cats of all ages
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What are the clinical signs of idiopathic vestibular disease?
- loss of balance
- ataxia
- disorientation
- nystagmus
- vomiting
- head tilt to the side of the lesion
- rolling or circling to side of lesion
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How do we diagnose idiopathic vestibular disease?
- clinical signs
- blood work to rule out underlying disease
- otic exam to rule out ear disease
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How do we treat idiopathic vestibular disease?
- no definitive therapy
- condition usually resolves on its own
- supportive therapy if needed - fluids, force feed
- residual head tilut or ataxia may persist
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What is metabolic neuropathy?
disease of the nervous system due to a metabolic disease - hypothyroidism, diabetes mellitus
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What can hypothyroid neuropathies occur with?
myopathies
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What are the clinical signs of hypothyroid neuropathy?
- progressive generalized weakness
- muscle atrophy
- dimished spinal reflexes
- laryngeal paralysis
- facial nerve paralysis
- vestibular disease
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What is the treatment for hypothyroid neuropathy?
- thyroid supplementation (soloxine)
- may take several months to see improvement
- may not fully recover
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What are the clinical signs of diabetes mellitus neuropathy?
- pelvic limb weakness
- muscle atrophy
- depressed spinal reflexes
- cats can have plantigrade stance and pelvic limb weakness
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How do we treat diabetes mellitus neuropathy?
treat the diabetes
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What is laryngeal paralysis?
- paralysis of laryngeal muscles
- airway obstruction occurs on inspiration
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What are the different types of laryngeal paralysis?
- congenital
- acquired
- idiopathic
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Which breeds are predisposed to congenital laryngeal paralysis?
- siberian husky
- bouvier des flandres
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What causes acquired laryngeal paralysis?
- lead poisoning
- rabies
- trauma
- inflammatory cell infiltration
- neuropathy
- myopathy
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Which breeds usually get idiopathic laryngeal paralysis?
middle aged to older large and giant breeds
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What are the clinical signs of laryngeal paralysis?
- high pitched inspiratory noise
- raspy inspiration
- worsens with exercise or heat stress
- voice change, gagging, coughing
- collapse
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How do we diagnose laryngeal paralysis?
- direct visualization of laryngeal motion - under opioid sedation or light general anesthesia
- failure of walls of larynx to abduct during inspiration
- ultrasound
- cervical and thoracic radiographs
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How do we treat laryngeal paralysis?
- surgical correction
- prognosis good to guarded
- do not breed animals that have hereditary paralysis
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What kind of disease is megaesophagus?
neurologic disease
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What causes megaesophagus?
- lack of effective peristalsis of esophagus
- generalized esophageal dilation
- regurgitation
- aspiration, aspiration pneumonia
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What are the two types of megaesophagus?
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When do we see congenital megaesophagus?
usually evident at weaning
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What is congenital megaesophagus?
chronic regurgitation of undigested food
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What is acquired megaesophagus?
dilation of esophagus
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What are the clinical signs of megaesophagus?
- regurgitation of food and liquids (distinguish between regurgitation and vomiting)
- hypersalivation
- repeated swallowing attempts
- halitosis from fermented ingesta
- respiratory distress (aspiration pneumonia, moist cough, crackles, dyspnea)
- malnutrition
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How do we diagnose megaesophagus?
- radiographs - gas/fluid/ingesta in esophagus, aspiration pneumonia
- esophagography - barium mixed into dog food
- fluoroscopy - with a barium swallow
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How do we treat megaesophagus?
- feed from elevated position
- keep animal elevated for 10 minutes postprandial
- frequent small meals
- vary consistency of food
- treat aspiration pneumonia
- motility modifiers of unproven benefit
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Is the prognosis good for megaesophagus?
generally poor and patient usually dies or is euthanized
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What causes tick paralysis?
prevents release of acetylcholine
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Which ticks cause tick paralysis?
- Dermacentor variabilis (common dog tick)
- Dermacentor andersoni (Rocky Mountain wood tick)
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What are the clinical signs of tick paralysis?
- develop 5 - 9 days after tick attachment
- weakness begins in rear legs
- ascends to thoracic limbs in 24 - 48 hours
- flaccid paralysis
- respiratory paralysis - death
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How do we diagnose tick paralysis?
- clinical signs - ascending flaccid paralysis
- presence of ticks
- improvement within 24 hours of tick removal
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How do we treat tick paralysis?
- remove ticks
- carefully examine for ticks - inside ears, interdigital spaces
- may need to clip long haired dogs
- Proban - cythioate can be used to remove hidden ticks
- supportive care
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What is Coonhound paralysis?
polyradiculoneuritis
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When did we first see coonhound paralysis?
first seen in 1954 after exposure to raccoon saliva - however, it can occur wtihout exposure to raccoon saliva
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What does the antigen in raccoon saliva cause?
nerve demyelination
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What kind of nerve damage does coonhound paralysis cause?
peripheral nerve damage
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Who gets coonhound paralysis?
adult dogs of any breed or sex
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What are the clinical signs of coonhound paralysis?
- begin 7 - 14 days post exposure
- spontaneous recovery begins as early as 1 week post exposure
- recovery may take several months
- recovery may be incomplete
- ascending flaccid paralysis
- if severe: cranial nerve deficits, respiratory paralysis
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How do we diagnose coonhound paralysis?
clinical signs and history
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How do we treat coonhound paralysis?
- no specific therapy
- supportive care while recovering
- support respiration if needed
- maintain soft bedding
- turn frequently
- maintain hydration and nutrition
- physical therapy and massage
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How do we educate clients on coonhound paralysis?
- dogs can get the disease without exposure to raccoons
- may require long-term nursing care
- may not regain total function
- may be prone to recurrence
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