Flashcards in DL: Neuro Cases (Holgar and Piercey) Deck (49):
What type of neuro problems do horses get?
- spinal/proprioceptive only!!
How does weakness manifest in horses?
- toe drag
- shuffly steps
> but can be d/t lameness/other ataxia too
How do proprioceptive tests in cats differ to dogs?
- much less sensitive in cats than dogs
- use table for concious proprioception in cats
- extensor postural thrust used more commonly in cats
How do CN reflexes/responses differ in cats cf. dogs?
- ^ Symp tone so poor PLR
- menace badly (make sure you do palpebral in between each meance)
Ddx for CSF with ^ protein, cell count esp neutrophils in a kitten?
- FIP (viral) test for corona virus but hard to dx d/t mutation (new test for specific protein coming out)
- toxoplasma gondii (protozoa) PCR/serology
- bacterial meningitis (very rare)
- fungal [Cryptococcus, hyalohyphomycosis, phaemohyphomycosis] (very rare)
Neuro signs associated with FIP?
- acute painful myelopathy
- brainstem and cerebellar most common
- seizures poss
- dry form = pyogranulomatous and immune complex mediated vasculitis -> gelatinousi nfiltrate into ventricles
- "inside and outside" affected -> meningitis and ventricles d/t blocked CSF outflow
How long can a horse be recumbent (down without being able to get up) for before you give up on it
What may ^WBCS and neutrophils on bloods be indivcative of?
Which bones protect the brainstem in horses? When may these be damaged?
- basisphenoid and basioccipital bones, rectus capitus m. underlies these
- should be in line, v thick bones
- can be fx if horse goes over backwards and hits head on floor
> do not ocnfused symphysis of bones for a fx
Damage to what n. may -> DDSP?
Where does the facial nerve course?
- stylomastoid foramen
- vertical ramus of the mandible
- across the masseter
> if muzzle only place affected = distal portion of facial n. affected (section overlying masseter)
Tx of progressive brainstem lesion?
- ^ dose steroids (no evidence for head trauma but do it anyway?)
- hyertonic saline/mannitol - only really useful in acute phase of disease
What does nystagmus indicate?
Acute onset as will compensate after a while
> peripheral vestibular lesion = horizontal
> central vestibular lesion = anything!!
- steroids and IFNw for palliative tx
What does hopping test detect mainly in horses?
Strength rather than coordination
Dx of FIP based on..?
- FCov Ab titre/IHC
- Alb: Glob ratio v (globulins in serum v high, A:G >0.8 r/o FIP, 0.4-0.8 consider other parameters)
- AGP (acid glycoprotein, an acute phase protein) levels >1500ug/ml
- haem: lymphopenia, non-regenerative anaemis, HCT
Clinical signs of head trauma in horses
- haemorrhage/CSF from skull (ear, nostril, mouth)
- blindness (sudden onset, fixed dilated pupils, papilloedema and retinl haemorrhage)
- longus capitus rupture -> caudo-medial aspect GP
- basisphenoid bone fx
Tx head trauma in the horse
- IV mannitol/hypertonic saline
- ?corticosteroids (no evidence, everyone does)
- supportive nursing care (decubital/corneal ulcers, pneumonia)
3 [potential diseases classified as MUO?
(meningitis of unknown origin)
> GME: granulomatous meningoencaphalitis
> NME: necoritising meningoencephalitis
> NLE: necrotising leukoencephalomyelitis
PDF for GME
- any breed but esp toy and terriers
- mean age ~5yrs
3 forms of GME?
- most common, multifocal disease
- single SOL, ddx neoplasia
- optic n. affected
- can progress -> focal/disseminate
- procarbazine +- pred
- radiation + pred
- cytarabine + pred
- cyclosporine +- steroids +- ketoconazole (best outcome)
What is NME? pdf?
> necortising meningioencaphalitis
= pug dog encephalitis (though other breeds shih Tzu, Lhasa apso, Chihuahua can get)
- 6mo-7yrs, mean 19months
- esp fawn coloured females
Clinical course of NME?
- few days/months before presentation
- FOREBRAIN signs (cerebrum +- thalamus)
- mean survival 93d (1-680d)
What is NLE? pdf?
> necrotising leucoencephalitis
- 1-10yrs mean 4.5yrs
- no sex predilection
- esp yorkies but others too
Clinical course of NLE?
- highly variable, usually chronic and progressive
- FOREBRAIN and BRAINSTEM
- altered mentation, seizures, central blindness, central vestibular signs
Viral causes of encephalitis
> Canine distemper encephalitis (CDE)
= immature/mature dogs = old dog encephalitis = chronic relapsing encephalomyelitis = post vaccinal CDE
- acute (most common) and chronic forms
- URT/GIT signs + myoclonus rhythmical contractions seen acutely
- furious (more common in cats, cerebral signs + aggression)
- dumb/paralytic form (brainstem signs, dropped jaw and swallowing difficulty)
Who should be contacted in a suspect rabies case?
Protozoal causes of encephalitis?
- toxoplasma gondii [dog and cat], neospora caninum [dog], sarcocystis neurona [horse]
- pathogenesis by ingestion of infected tissue
Clinical signs associated with toxoplasmosis/neosporosis?
- seizures and cerebellar signs, neuromuscular
- systemic and ocular involvement
Disgnosis of toxoplasmosis/neopsporosis?
- IgM/G serology
- CSF mixed cell pleiocytosis
- PCR on CSF
> 8-12 weeks
- TMPS 15mg/kg/BID
- Clindamycin 20mg/kg BID
Bacterial causes of encephalitis? Diagnostic indicators and Tx?
VERY RARE in dogs, cts and horses
- haematogenous/local invasion
- severe neutrophilic pleiocytosis
- intracellular bacteria/bacterial culture from CSF
- aggressive Abx to tx, ideally based on culture
Parasitic causes of encephalitis?
> A. vasorum (metastrongyloid nematode) -> coagulopathy
Clinical signs of a. vasorum encephalopathy?
- mainly young dogs
- cough + dyspnoea (essentially d/t interstitial pneumonia)
- subcut swelling/haemorrhage
- coagulopathy and thrombocytopenia
Outline the lifecycle of A> Vasorum
> L1-L3 development in the snail
> eaten by dog
> penetrates GIT and develops in mesenteric LNs -> L5
> Liver, portal v. -> Pulm a. and RV (10d post infection)
> in heart , maturation in ~ 1month post-infect
> adults shed eggs
> develop -> L1 in pulm aa.
> L1 penetrate cepillaries and alveolar walls
> coughed up and swallowed
> pooped out
-> Cycling beings again
How can A. Vasorum cause a coagulopathy? What linical parameter is this associated with?
- eosinophilia -> hypersensitivity
- cellular response
- deposition of immune complexes d/t adults irritating BVs
- inappropriate activation of clotting uses up platelets
- eggs hatching also inhibit thrombocytopoeisis
> intravascular consumptive coagulopathy overall
- prolonged APPT time observed clinically
Causes of head tilt in horses?
- trauma eg. basisphenoid bone fx
- temporohyoid osteoarthropathy
- otitis media/interna (rare)
What is head tilt often seen in association with in horses?
facial n. signs
Aetiology of temporohyoid osteoarthropathy?
- chronic otitis media/interna
- infection spreads to tympanohyoid joint and stylohyoid bnoe
- inflame fuses tympanohyoid joint
- degenerative hanges over time
- muscle contraction mechanimal forces (swallowing/mastication) induce pathological fx extending into petrous temporal bone
Tx temporohyoid Osteoarthropathy?
- ceratohyoid bone removal
Prognosis for temporohyoid osteoarthropathy?
- 67% survival
~ 50% will have residual vestibular +/+- facial deficits
- recovery takes >1yr
- risk of relapse
How can thiamine levels be assessed ?
- pyridoxal diphosphate assay on whole blood by HPLC (high performance liquid chromatography)
Blood thiamine ref range?
Pathogensis of thiamine deficiency?
> thiamine (vit B1) important for oxidative metabolism of many nutrients
- 4 reasons:
> reduced uptake
- thiamine deficient food d/t overheating
- thiaminase activity of fish, bracken etc.
- sulphur dioxide
> v absorption
> ^ consumption
Clinical signs of thiamine deficiency?
- vestibular signs
- pupillary dilation/absent PLR
- cats = head ventroflexion
Diagnostic tools for thiamine deficiency
- MRI: bilat symmetrical lesionin brainstem nuclei
- transketolase activity in erythrocytes
- ^ certain urinary organi acids (2-oxo/hydroxyadipate)
Tx thiamine deficiency?
- sc q24hrs until oral supplemetns can be given