Neuro

Question 1

DDX of vestibular disease in horses ?

Answer 1

• Temporohyoid osteoarthropathy (+++)
• Otitis media and interna (bacterial, viral, fungal, parasitic or neoplasia)
• Trauma (collision, kick, or flipping over)
• Infectious : EPM in USA, Lyme (Borrelia burgdorferi), aberrant parasite migration (Halicephalobus gingivalis), meningitis, brain abscess

Vestibular disease in horses: Recognition, localisation and common causes
(Clinical commentary) EVE 2024

Question 2

What is Juvenile Idiopathic Epilepsy ? (breed, age, clinical signs, prognosis)

Answer 2

Juvenile idiopathic epilepsy (JIE) is a self-limiting disorder in Egyptian Arabian foals, with an early onset of seizures ranging from 2 days to 6 months of age, with apparent resolution within 1 to 2 years of life with no known long-term neurologic sequelae. Prognosis for life and athletic performance generally is good provided no life-threatening complications occur.

Electroencephalographic evaluation under standing sedation using sublingual detomidine hydrochloride in Egyptian Arabian foals for investigation of epilepsy
JVIM 2023

Question 3

What is the suspected mode of inheritance of Juvenile Idiopathic Epilepsy in Arabian foals ?
What is the most common postictal sign ?

Answer 3

JIE in foals has a familial basis and is suspected to be inherited in an autosomal dominant manner with a self-limiting pattern, likely with incomplete penetrance resulting in some asymptomatic foals (siblings of affected foals).
Cortical blindness is the most common postictal sign.

Juvenile idiopathic epilepsy in Egyptian Arabian foals, a potential animal model of self-limited epilepsy in children
JVIM 2024

Question 4

What have been identified in eNAD/EDM affected QH ?
* decreased α-tocopherol metabolism
* increased α-tocopherol metabolism
* increased α-tocopherol and γ-tocopherol metabolism
* decreased hepatic expression of metabolizer of vitamin E (CYP4F2)

Answer 4

Metabolic rate of α-tocopherol was increased in serum and urine of eNAD/EDM horses, with no difference in the metabolic rate of γ-tocopherol.
Increased expression of CYP4F2 → likely a consequence of the underlying genetic etiology of eNAD/EDM.

Increased α-tocopherol metabolism in horses with equine neuroaxonal dystrophy
JVIM 2021

Question 5

What is the main hypothese(s) associated with increased CSF pNfH (> 3 ng/mL) ?
What is the main hypothese(s) associated with increased blood pNfH (> 1 ng/mL) ?

Answer 5

Increased CSF pNfH concentrations (>3 ng/mL) can be observed with eNAD/EDM or CVCM.
Serum pNfH concentrations are specifically increased (>1 ng/mL) in some horses with eNAD/EDM (but low sensitivity).

Serum and cerebrospinal fluid phosphorylated neurofilament
heavy protein concentrations in equine neurodegenerative
diseases
EVJ 2022

Question 6

Which factor is associated with normalization of vitamine E dosage post-supplementation?
Hypothesis of transmission ?

Answer 6

Significantly associated with age, older horses were more likely to respond appropriately to supplementation.
Hyp : autosomal dominant transmission with incomplete penetrance or polygenic

Equine neuroaxonal dystrophy/degenerative
myeloencephalopathy in Gypsy Vanner horses
JVIM 2024

Question 7

True or false : A mutation in CD36 is responsible of eNAD/EDM in QH.

Answer 7

False
2 intronic CD36 SNPs were significantly associated with eNAD/EDM in QHs. However, many postmortem-confirmed cases of eNAD/EDM were wild-type (non-mutated) for these variants. We either identified a false positive association or genetic heterogeneity exists for eNAD/EDM within the QH breed.

Genetic polymorphisms in vitamin E transport genes as
determinants for risk of equine neuroaxonal dystrophy
JVIM 24

Question 8

What are the 2 clinical presentations of eNAD/EDM ?

Answer 8

Initial descriptions identified young horses (birth to 2 years) of specific breeds (Arabians, TB, QH and Morgan), with symmetric ataxia, tetraparesis, and general proprioceptive tract lesions.
Second identified presentation : adult horses (median age 8 yo), majority of Warmbloods, with behavioral changes and proprioceptive ataxia.

Clinical and histopathological features in horses with
neuroaxonal degeneration: 100 cases (2017-2021)
JVIM 2024

Question 9

What is 8-hydroxy-2’-deoxyguanosine (8-OHdG) a biomarker for ? Is it efficient to antemortem diagnose eNAD/EDM ?

Answer 9

8-OHdG is a commonly used biomarker of oxidative damage, extensively studied in humans with neurodegenerative diseases.
8-OHdG did not aid in antemortem diagnosis of eNAD/EDM in this cohort of horses.

Measurement of 8-hydroxy-20-deoxyguanosine in serum and
cerebrospinal fluid of horses with neuroaxonal degeneration
and other causes of proprioceptive ataxia
JVIM 2024

Question 10

Which breed is most likely to show severe muscular symptoms in cases of anaplasmosis?

Answer 10

Muscle disease was less common, with QH breeds with the variant causing myosin heavy chain myopathy (MYHM) having severe disease.

Common and atypical presentations of Anaplasma
phagocytophilum infection in equids with emphasis
on neurologic and muscle disease
JVIM 2024

Question 11

What is the current known etiology of shivering in horses?

Answer 11

Our findings support axonal degeneration of Purkinje cells in the cerebellum, without a substantial impact on Purkinje cells soma.

Cerebellar axonopathy in Shivers horses identified by spatial
transcriptomic and proteomic analyses
JVIM 2023

Question 12

What is the current hypothesis when faced with an acute onset of neurological deficits, with decubitus, high GGT and hyperglycemia, in a QH foal (< 1 month) ?
Hypothetical etiology ?

Answer 12

Equine Juvenile Spinocerebellar Ataxia (EJSCA) is a uniformly fatal, rapidly progressive, likely autosomal recessive neurological disease of QHs <1 month of age in North America.

Clinicopathological and pedigree investigation of a novel
spinocerebellar neurological disease in juvenile Quarter Horses
in North America
JVIM 2024

Question 13

What is the most frequent in a population of horses ?
- Selenium deficiency
- Vitamine E deficiency
- β-carotene deficiency
- selenium overdose

Answer 13

• Selenium deficiency
  - Vitamine E deficiency
• β-carotene deficiency
• selenium overdose
  in Oregon despite most owners providing supplementation.

Influence of specific management practices on blood selenium,
vitamin E, and beta-carotene concentrations in horses and risk
of nutritional deficiency
JVIM 2020

Question 14

What is the safety and efficacy of subcutaneous alpha-tocopherol administration in horses ?

Answer 14

Parenteral administration of ⍺-tocopherol via the subcutaneous route effectively increases serum and CSF ⍺-tocopherol concentrations.
But the tested product is not safe for use in horses due to local tissue reaction and as such cannot be recommended for clinical use at this time.

Safety and efficacy of subcutaneous alpha-tocopherol in healthy
adult horses
eve 2021

Question 15

What is the impact of vitamin E depletion in healthy juvenile horses ?

Answer 15

Vitamin E depletion may elevate CSF pNfH in otherwise healthy juvenile foals by 6 months of age, compatible with subclinical axonal degeneration.

Vitamin E depletion is associated with subclinical axonal
degeneration in juvenile horses
evj 2023

Question 16

Which seems to be the most accurate for discriminating healthy vs eNAD vs CVCM horses : protein test using serum or CSF ?

Answer 16

Modeling indicated that a 2-protein test using CSF had the highest accuracy for discriminating among all 3 groups. CSF R-spondin 1 (RSPO1) and neurofilament-light (NEFL)
Future studies to validate these markers in larger replication cohorts are required before clinical adoption of these biomarkers.

Cerebrospinal fluid and serum proteomic profiles accurately
distinguish neuroaxonal dystrophy from cervical vertebral
compressive myelopathy in horses
JVIM 2023

Question 17

What are the key findings regarding juvenile idiopathic epilepsy (JIE) in Egyptian Arabian foals based on EEG and clinical observations?

A) EEG findings showed generalized epileptic discharges in 60% of JIE foals, originating from random cortical regions, and there were no postictal signs like cortical blindness.

B) Most JIE foals experienced focal seizures, with EEG abnormalities being rare and only occurring during wakefulness, unrelated to genetic factors.

C) Focal epileptic discharges originating from the central vertex were observed in 95% of JIE foals. Seizures were mostly generalized tonic-clonic, with postictal signs like cortical blindness, and photic stimulation triggered discharges in 62% of the foals. Asymptomatic siblings also showed EEG abnormalities, suggesting genetic susceptibility.

D) Juvenile idiopathic epilepsy in foals primarily manifests as focal seizures, with generalized tonic-clonic seizures being rare, and all foals responded to antiseizure medications without exception.

Answer 17

Answer: C.

A) INCORRECT-> mentions no postictal signs and generalized discharges in 60% of foals. The paper states postictal signs were observed, and generalized seizures occurred in 86% of foals​

B) INCORRECT->claims focal seizures are common and EEG abnormalities are rare. In reality, generalized seizures were the majority (86%), and 95% of JIE foals had EEG abnormalities​

C)CORRECT
Focal epileptic discharges originating from the central vertex were observed in 95% of JIE foals (n = 35/37) in the form of focal spike-and-wave discharges;
Seizures were mostly generalized tonic-clonic:
Clinically, 41 of 48 JIE foals had generalized seizures… Seizures were characterized as violent generalized tonic-clonic with a facial motor component, trismus, and loss of consciousness.
ostictal signs like cortical blindness:
Postictal signs included disorientation, obtundation, cortical blindness, mydriasis, decreased palpebral reflex, lack of suckle reflex, dysphagia, tongue protrusion, proprioceptive deficits of all limbs, and ataxia.
Intermittent PS [photic stimulation] resulted in photoparoxysmal responses in the form of ED in the central or centroparietal regions in 62% (n = 13/21) of JIE foals.
Asymptomatic siblings also showed EEG abnormalities, suggesting genetic susceptibility:In 3 control foals, focal spike and waves discharges occasionally were observed… None of these 3 control foals had a history of epilepsy, but all had a family history of a sibling with JIE

D)INCORRECT: suggests focal seizures are predominant and all foals responded to treatment, but the paper clearly states that generalized tonic-clonic seizures were more frequent, and 6% of foals were resistant to treatment​

2023 Juvenile idiopathic epilepsy in Egyptian Arabian foals JVIM

Question 18

In horses diagnosed with Shivers, which of the following best describes the primary pathological finding in the cerebellum?

A) Degeneration of Purkinje cell (PC) soma with significant gene expression changes.
B) Loss of myelin proteins in the cerebellar cortex.
C) Axonal degeneration in the cerebellar white matter with minimal changes in the Purkinje cell soma.
D) Neurofilament accumulation in Purkinje cell bodies causing axonal atrophy.

Answer 18

answer: C

A) Incorrect. The study found no significant differential gene expression in Purkinje cell soma between Shivers and control horses. The primary pathology was in the axons, not the soma​.

B) Incorrect. While the study did find a reduction in myelin-related proteins, this occurred primarily in the cerebellar white matter, particularly in the axonal regions, not limited to the cortex​.

C) Correct. The primary finding in Shivers horses was axonal degeneration in the cerebellar white matter, particularly in regions rich in axons. There were minimal changes in the Purkinje cell soma, consistent with axonal degeneration without significant soma involvement​.

D) Incorrect. While neurofilament proteins were reduced in Shivers horses, the pathology involved axonal degeneration, not accumulation in the Purkinje cell bodies.​

Cerebellar axonopathy in Shivers horses identified by spatial
transcriptomic and proteomic analyses 2023