Small animal neurology Flashcards
Rabies virus is common where
Endemic in N. America
Some island nations are rabies free
Reservoir is in wildlife
Most common in bats
How is rabies transmitted
Short-lived outside host
#1 cause of infection in dogs is contact with rabid wildlife
#1 cause in people worldwide is bite by rabid dog
Transmission from bats is becoming more common due to vaccination
Direct transmission
Bites
Saliva (MM, scratches, wounds)
How long does it take for rabies to get to the system
The virus get to the brain from the infection site between 3 weeks and 6 months
What are the stages of rabies
Prodromal
- Change in behaviour, mild ADR
Excitation
- Furious form of rabies most obvious
- Aggressive/attack; hypersalivation
Paralytic
- Can also present with dumb form
- Ascending hind end paralysis (polyradiculoneuritis)
Eventually leads to death
What will make you suspicious of rabies
Contact with wildlife (watch for urban bats)
Lack of vaccination
Changes in behaviour/aggression
Neurological signs
Hypersalivation, hind end neuropathy
Paresis (tremors), paralysis, seizures (fly biting seizures)
How do you diagnose rabies
Diagnosis is made by POST-MORTEM examination of the brain
How do you treat/prevent rabies
NO treatment in animals
Do treat all in contact people
“Post exposure prophylaxis”
Prevent in animals by vaccination
What is the rabiess vaccine
Core
Import/export requirement
No provincial requirement in SK
Some municipalities may require that domestic animals be vaccinated for rabies
Regulated by CFIA
On label only
Administered by a licensed DVM
Proof of rabies vaccination
Proof of titers in animals is not equivalent to vaccination
Do you report cases of rabies
Rabies is a federally reportable disease
Where and how do you report rabies
Must report to CFIA
Indirect reporting
Saskatchewan rabies response program
Clinical assesses if rabies suspect
If yes, contact the RRAV (rabies risk assessment veterinarian)
RRAV contacts CFIA for instructions for that animal
RRAV will inform you of what steps to take )isolate, observe, euthanize and submit)
Of there was human contact, contact public health or 811
Of you are bit- immediately wash the wound with soap and water and see an MD ASAP
What is the outcome with wildlife and rabeis
Euthanized- avoid trauma to the animals head
Contact a local conservation officer for testing
What happens to an animal with suspected rabies that is unvaccinated and has no bite
Unvaccinated; suspected rabies; no bite
Contact RRAV
Quarantine (1 week if any clinical signs; up to 6 mo)
Euthanize and test
What happens to unvaccinated aniamls with a bite for rabies
Unvaccinated; suspect rabies; possible bite
Contact RRAV and quarantine animal
Will likely be ordered to euthanize and test
What do you do for an animal with suspected rabies that is UTD on vaccines
Up to CFIA; more likely to monitor under quarantine
Is rabies zoonotic and how
Zoonotic; fatal if not addressed
Public health
How to prevent zoonotic transmission of rabies
Gloves and face shield
Dog bite prevention
Wash with soap and water; flush mucus membranes
Rabies vaccines
Preventative vaccine in people that are at an increased risk of coming into contact with infected animals
Dogs and cats; ferrets; horses; livestock
Post exposure prophylaxis
What is canine distemper virus
Highly contagious
Endemic in sk
Virus is stable in organic matter for up to 2y
Susceptible to heat and disinfectants
How is distemper transmitted
aerosolization of infected bodily secretions, ingestion, direct contact
Who commonly gets distemper
Young dogs (3-6 months)- UNVACCINATED
How severe is distemper to unvaccinated
Clinical distemper- fatal neurological disease
How severe is distemper with vaccinated dogs
> 99.9% protection from fatal disease
Mild self limiting gastroenteritis or upper resp disease
Can still shed the virus
What is stage 1 of clinical distemper
Early (non neuro) stage
Opportunistic infections
V/D, inappetence
coughing/gagging
Ocular and nasal discharge
What is stage 2 of clinical distemper
Remission stage - virus becomes latent, asymptomatic for weeks to months
This stage does not always occur
What is stage 3 of clinical distemper
Neurological signs- virus infects brain and other neurons
Hyperkeratosis of footpads
Muscle wasting
Ataxia, circling
Blindness
Chewing gum seizures
Muscle rigidity to rigid paralysis
How do you diagnose distemper
History– unvaccinated +/- exposure to unvaccinated animals
Clinical signs
Diagnostic
Serum titers for antibodies
Fluorescent antibody test for virus in tissues
PCR
How do you treat distemper
Can not treat the condition, treat the symptoms
What is the prognosis of distemper
Poor - almost 100% fatal
How to prevent distemper
Vaccination
What is cerebral edema
Swelling of the brain
What can cause cerebral edema
Many causes
Anything that causes inflammation
Non-inflammatory causes
Usually related to pressure build up
Common iatrogenic causes of cerebral edema include
Fluid overload
Lack of oxygenation during GA
What is the pathophysioloy of cerebral edema
Fluid accumulation
Limited size or cranium
Causes increased pressure
Compression
Herniation (cerebellum, brainstem)
What are clinical signs of cerebral edema associated with
Associated with where in the brain compression or herniation occurs
Ex
Brainstem- drop in HR, RR, temp
Cerebrum- changes in mentation or seizures
Visual cortex- cortical blindness
Cerebellum- vestibular signs
What are the common clinical signs of cerebral edema
Decreased mentation
Lethargy → obtunded→ stupor→ coma
Ataxia, hypermetria
Rigid and extended limbs
Seizures
Ocular changes
Dilated pupils, anisocoria(one pupil bigger than another)
Abnormal nystagmus (vertical or rotational)
Central blindness
How do you respond to possible cerebral edema
Get vet
Check vitals
IV catheter
Fluids
IV fluids if shock
Stop fluids if fluid overload
Emergency diuresis to remove extra fluid pressure
Provide oxygen support
Treat seizures, treat inflammation
Diagnostics
What should you do if POSSIBLE signs of cerebral edema
Recognize as emergency
Consider the change and the context in which it occurs
Be smart
If the clinical picture is subtle, but fits with the history of event , err on the side of caution
Other causes of compression and herniation are
Any time something extra is added to the cranium or intracranial space
Cerebral edema
Brain tumor
Meningeal tumor
Pituitary tumor
Bleeding
Pieces of cranium
What is ischemia and what does it cause
lack of blood flow
Affects nutrients and oxygen delivery
Neurons rapidly become damaged
What does hypoxia mean and what is it caused by
lack of oxygen
May be caused by lack of blood flow, amount of Hgb, lack of oxygen, cant breath
What are the risk factors with cerebral hypoxia and ischemia
Any cause of decreased BP
Any cause of decreased ventilation
Increased risk with GA
Risk is even greater if
Bleeding
Not on IV fluids
Overdose certain drugs used in GA
Lack of 100% O2
Wha is the prognosis with cerebral hypoxia and ischemia
Nerves in the CNS do not regenerate
Cna form new connections
What are seizures and how are they dagnosed
Clinical signs
Abnormal (usually increased) conductivity
Lesion is in the cerebrum
What are common causes of seizures
Hypoglycemia ← easiest to test for
Idiopathic epilepsy ← no diagnostic test available
Any compression: edema (inflammation), tumor, bleeding, hydrocephalus, ischemia/hypoxia (inflammation), trauma
Anatomical defect
Infection
Toxicity
Insecticides
Lead
Strychnine
Slug poison
Many other causes
What are some common types of seizures
Grand mal
Focal seizure
Petit mal
Status epilepticus
Cluster seizures
What is status epilepticus
Series of seizures, the animal does not regain consciousness in between
Single episode longer than 30 min
What are cluster seizures
More than one seizure within a 24 hour period
Period of normal behaviour between each seizure episodes
What has idiopathic epilepsy
Dogs, all species
Some breed predisposition
What are the 3 stages of seizures
Pre ictal
Ictal (seizure) ← time this segment (less than 5 mins)
Postictal ← less than 1 hour
When do you start treatment for seizures
Can be close together or years apart
Usually progressive
Start chronic treatment when
More frequent
More sever
Longer duration
What are some history findings needed for seizures
When was the first one? Years, months, weeks?
Describe from start to finish
Common triggers/events
Possible toxicity
medications/drugs
If already medicating, find out if any missed doses of medication, changes in diet or treated being given
Diagnosis by ruling out other diseases
Don’t just focus on this one symptom
How do you treat seizures
Maintenance therapy
Emergency drugs
What are maintenance therapy used for seizures
Life long
No missed disease
Goal is to decrease severity and frequency of episodes
Does not eliminate seizures
Phenobarbital
Potassium bromide (KBr)
Levetiracetam
What are emergency drugs for seizures
Stops current seizure
Treatment of status epilepticus
Prevents progression to status epilepticus or cluster seizures
Given during or immediately following a seizure
Diazepam
IV phenobarbital
Propofol
What should a seizure diary include
Owners to write down and track seizures
Potential triggers
Identify pre-ictal signs
Duration of ictal period
Frequency of seizures
More frequent, longer duration, more severe?
How should you respond to a seizure
NPO- choke/aspiration hazard
Do not attempt to place an IV
Check BG- hypoglycemia?
Emergency diazepam (Valium)
Per rectum
Repeat if still seizing after 15 minutes
What are the pathophysiology with insecticides
Normally, acetylcholine (Ach) is released and turns on the postsynaptic response
Turns on muscle (if at a neuromuscular junction)
Turns on neurons in the parasympathetic NS and CNS
Normally, acetylcholinesterase is released into the space → degrades ACh → turns off response
These drugs block acetylcholinesterase
Muscles can’t turn off, parasympathetic response stays on
Turns up PSNS and causes resp paralysis
What is the pathology of insecticides
Increase parasympathetic response → respiratory, CV depression
Rigid paralysis – paralyzed resp muscles
Increased transmission in the brain → seizures→ coma
What is IVDD
Intervertebral disk disease
Slipped disk, ruptured disk, prolapsed disk
“Back dogs”
What is the pathophysiology of IVDD
Intervertebral disc hardens or weakens
Sudden force causes it to rupture or shift
Degenerative change
If the disk material prolapses dorsally, it pushes against the spinal cord
Compresses the nerves causing pain and prevents their proper function
What breeds are predisposed to IVDD
Dachshund
Basset hounds
Corgi
French bulldog
Shih tzu
What is acute IVDD and what is the response
Emergency
Usually traumatic
VERY painful
+/- neurological signs
Ataxia
Paralysis
What does chronic IVDD look like
Degenerative
Possible prior injury
Usually less pain or neuro effects at the time of initial diagnosis
When is IVDD an emergency
Acute pain
Acute neurological signs
Acute ataxia
Acute paresis or paralysis
Listed for
Traumatic event
“All of a sudden…”
Chronic IVDD is not an emergency
How should you handle a dog with IVDD
Handle with care
Painful
May require a muzzle
Will require analgesic
Watch out when handling to not cause further disk rupture
Do not apply pressure to affected area
NO COLLARS
Support body area affected
How do you treat and prevent IVDD
Depends on area affected and severity of clinical signs
Medical management
Surgical repair
Weight control in high risk breeds
Limit jumping on and off of furniture, steps…
Strict cage rest up to 8 weeks, not a kennel run a kennel
What is wobblers syndrome
Cervical IVDD or narrowed vertebral canal
Large and giant breeds
Dobermans- mean 6yo
Great danes - mean 3yo
