Podcast
Questions and Answers
What is the primary role of Vitamin E in preventing Equine Degenerative Myelopathy (EDM)?
What is the primary role of Vitamin E in preventing Equine Degenerative Myelopathy (EDM)?
- Boosting the immune response to central nervous system antigens.
- Enhancing the structural integrity of neurons.
- Promoting the synthesis of myelin sheath around nerve fibers.
- Preventing oxidation of membrane lipids within the central nervous system. (correct)
Which of the following best describes the characteristic clinical presentation of Equine Protozoal Myeloencephalitis (EPM)?
Which of the following best describes the characteristic clinical presentation of Equine Protozoal Myeloencephalitis (EPM)?
- Rapidly progressive muscle atrophy with hypersensitivity to touch.
- Gradual onset of asymmetric neurological deficits. (correct)
- Sudden collapse followed by generalized seizures.
- Acute onset of symmetrical ataxia affecting all four limbs equally.
What is the significance of the N752/D752 mutation in the context of Equine Herpes Myeloencephalitis (EHM)?
What is the significance of the N752/D752 mutation in the context of Equine Herpes Myeloencephalitis (EHM)?
- It is a marker for increased shedding of the virus, leading to higher transmission rates.
- It is associated with the neuropathogenic strains of EHV-1 due to a mutation at position 752. (correct)
- It shows an increased likelihood of abortion in pregnant mares infected with the virus.
- It indicates a stronger immune response, mitigating the severity of neurological signs.
Which diagnostic approach offers the most accurate assessment of disease likelihood in cases of Equine Protozoal Myeloencephalitis (EPM)?
Which diagnostic approach offers the most accurate assessment of disease likelihood in cases of Equine Protozoal Myeloencephalitis (EPM)?
What is the most critical factor to consider when collecting cerebrospinal fluid (CSF) for diagnosing Equine Protozoal Myeloencephalitis (EPM)?
What is the most critical factor to consider when collecting cerebrospinal fluid (CSF) for diagnosing Equine Protozoal Myeloencephalitis (EPM)?
A horse presents with clinical signs suggestive of Equine Degenerative Myelopathy (EDM). Serum vitamin E levels are marginal. What additional information would be most useful in supporting a diagnosis of EDM?
A horse presents with clinical signs suggestive of Equine Degenerative Myelopathy (EDM). Serum vitamin E levels are marginal. What additional information would be most useful in supporting a diagnosis of EDM?
Which statement accurately articulates the current understanding of the role of vaccines in managing Equine Herpes Myeloencephalitis (EHM)?
Which statement accurately articulates the current understanding of the role of vaccines in managing Equine Herpes Myeloencephalitis (EHM)?
What is the primary reason for the guarded prognosis associated with Equine Degenerative Myelopathy (EDM), even with early and consistent treatment?
What is the primary reason for the guarded prognosis associated with Equine Degenerative Myelopathy (EDM), even with early and consistent treatment?
What is the primary rationale behind administering nonsteroidal anti-inflammatory drugs (NSAIDs) in the early stages of managing Equine Herpes Myeloencephalitis (EHM)?
What is the primary rationale behind administering nonsteroidal anti-inflammatory drugs (NSAIDs) in the early stages of managing Equine Herpes Myeloencephalitis (EHM)?
Which key element in the life cycle of Sarcocystis neurona is most critical to target when implementing preventative measures against Equine Protozoal Myeloencephalitis (EPM)?
Which key element in the life cycle of Sarcocystis neurona is most critical to target when implementing preventative measures against Equine Protozoal Myeloencephalitis (EPM)?
What is the primary mechanism of action of ponazuril and diclazuril, the FDA-approved medications for treating Equine Protozoal Myeloencephalitis (EPM)?
What is the primary mechanism of action of ponazuril and diclazuril, the FDA-approved medications for treating Equine Protozoal Myeloencephalitis (EPM)?
In cases of Equine Herpes Myeloencephalitis (EHM), what is the significance of xanthochromia upon cerebrospinal fluid (CSF) analysis?
In cases of Equine Herpes Myeloencephalitis (EHM), what is the significance of xanthochromia upon cerebrospinal fluid (CSF) analysis?
A horse is suspected of having Equine Degenerative Myelopathy (EDM) based on clinical signs. If postmortem necropsy is performed; where would be the most important region to examine for characteristic lesions?
A horse is suspected of having Equine Degenerative Myelopathy (EDM) based on clinical signs. If postmortem necropsy is performed; where would be the most important region to examine for characteristic lesions?
A horse displays asymmetric ataxia and muscle atrophy. If Equine Protozoal Myeloencephalitis (EPM) is suspected; where should you collect CSF to increase test sentitivity?
A horse displays asymmetric ataxia and muscle atrophy. If Equine Protozoal Myeloencephalitis (EPM) is suspected; where should you collect CSF to increase test sentitivity?
When assessing a horse with suspected Equine Herpes Myeloencephalitis (EHM) during an outbreak, what is the most appropriate protocol regarding isolation?
When assessing a horse with suspected Equine Herpes Myeloencephalitis (EHM) during an outbreak, what is the most appropriate protocol regarding isolation?
A horse is diagnosed with Equine Protozoal Myeloencephalitis (EPM) and treated with an FDA-approved medication. Despite initial improvement, the horse relapses several months later. What is the most important consideration for managing the relapse?
A horse is diagnosed with Equine Protozoal Myeloencephalitis (EPM) and treated with an FDA-approved medication. Despite initial improvement, the horse relapses several months later. What is the most important consideration for managing the relapse?
Which of the following is the most critical component in designing a biosecurity protocol to prevent the spread of Equine Herpes Myeloencephalitis (EHM) in a large boarding facility?
Which of the following is the most critical component in designing a biosecurity protocol to prevent the spread of Equine Herpes Myeloencephalitis (EHM) in a large boarding facility?
In the context of managing Equine Degenerative Myelopathy (EDM), what is the primary goal of advising Vitamin E supplementation in predisposed individuals?
In the context of managing Equine Degenerative Myelopathy (EDM), what is the primary goal of advising Vitamin E supplementation in predisposed individuals?
What is the implication of a negative test for Sarcocystis neurona in a horse displaying clinical signs of neurological disease?
What is the implication of a negative test for Sarcocystis neurona in a horse displaying clinical signs of neurological disease?
What is the rationale for using valacyclovir in the treatment of Equine Herpes Myeloencephalitis (EHM)?
What is the rationale for using valacyclovir in the treatment of Equine Herpes Myeloencephalitis (EHM)?
What is the best description of the typical signalment of horses that develop Equine Degenerative Myelopathy (EDM)?
What is the best description of the typical signalment of horses that develop Equine Degenerative Myelopathy (EDM)?
Which of the following clinical signs is most suggestive of Equine Herpes Myeloencephalitis (EHM) rather than Equine Protozoal Myeloencephalitis (EPM)?
Which of the following clinical signs is most suggestive of Equine Herpes Myeloencephalitis (EHM) rather than Equine Protozoal Myeloencephalitis (EPM)?
What characteristic finding on CSF analysis is most suggestive of Equine Herpes Myeloencephalitis (EHM)?
What characteristic finding on CSF analysis is most suggestive of Equine Herpes Myeloencephalitis (EHM)?
What statement best summarizes the approach to managing Equine Protozoal Myeloencephalitis (EPM) to minimize the risk of relapse after successful treatment?
What statement best summarizes the approach to managing Equine Protozoal Myeloencephalitis (EPM) to minimize the risk of relapse after successful treatment?
How could Equine Protozoal Myeloencephalitis be prevented?
How could Equine Protozoal Myeloencephalitis be prevented?
When does relapse occur for Equine Protozoal Myeloencephalitis (EPM)?
When does relapse occur for Equine Protozoal Myeloencephalitis (EPM)?
Which of the following is not a clinical sign of Equine Herpes Myelitis (EHM)?
Which of the following is not a clinical sign of Equine Herpes Myelitis (EHM)?
The gene sequence determines pathogenicity for Equine Herpes Virus. Which has a high virulance in order?
The gene sequence determines pathogenicity for Equine Herpes Virus. Which has a high virulance in order?
Which of the following has FDA approval for Equine Protozoal Myeloencephalitis (EPM) treatment?
Which of the following has FDA approval for Equine Protozoal Myeloencephalitis (EPM) treatment?
Which of the following is not a cause of Equine spinal ataxia?
Which of the following is not a cause of Equine spinal ataxia?
Which of the following breeds are not predisposed to Equine Degenerative Myelopathy (EDM)?
Which of the following breeds are not predisposed to Equine Degenerative Myelopathy (EDM)?
How often should a horse be treated with Propionibacterium acnes if following label instructions?
How often should a horse be treated with Propionibacterium acnes if following label instructions?
What lesion region would be associated with Equine Protozoal Myeloencephalitis?
What lesion region would be associated with Equine Protozoal Myeloencephalitis?
What is the relationship between Equine Herpesvirus-1 respiratory infection and Equine Herpes Myeloencephalitis (EHМ)?
What is the relationship between Equine Herpesvirus-1 respiratory infection and Equine Herpes Myeloencephalitis (EHМ)?
At what vitamin E µg/mL level is a horse considered normal and adequate to support neurologic and muscular function?
At what vitamin E µg/mL level is a horse considered normal and adequate to support neurologic and muscular function?
What serum:CSF ratio result would indicate a postive EPM test?
What serum:CSF ratio result would indicate a postive EPM test?
What is the primary neuropathological finding that differentiates Equine Degenerative Myelopathy (EDM) from Neuroaxonal Dystrophy (NAD)?
What is the primary neuropathological finding that differentiates Equine Degenerative Myelopathy (EDM) from Neuroaxonal Dystrophy (NAD)?
Considering the complex interplay of factors contributing to Equine Degenerative Myelopathy (EDM), which of the following best describes its etiology?
Considering the complex interplay of factors contributing to Equine Degenerative Myelopathy (EDM), which of the following best describes its etiology?
A veterinary practice is located in a region with a known high seroprevalence of Sarcocystis neurona. Which of the following strategies would be most effective in reducing the incidence of new Equine Protozoal Myeloencephalitis (EPM) cases?
A veterinary practice is located in a region with a known high seroprevalence of Sarcocystis neurona. Which of the following strategies would be most effective in reducing the incidence of new Equine Protozoal Myeloencephalitis (EPM) cases?
A horse exhibits asymmetric ataxia, hindlimb weakness, and focal muscle atrophy. Diagnostic testing confirms Equine Protozoal Myeloencephalitis (EPM). Despite treatment with an FDA-approved medication, the horse shows only marginal improvement. What is the most appropriate next step?
A horse exhibits asymmetric ataxia, hindlimb weakness, and focal muscle atrophy. Diagnostic testing confirms Equine Protozoal Myeloencephalitis (EPM). Despite treatment with an FDA-approved medication, the horse shows only marginal improvement. What is the most appropriate next step?
In a large equine practice, a cluster of horses suddenly develop neurological signs, including fever, ataxia, and urinary incontinence. Equine Herpes Myeloencephalitis (EHM) is suspected. What immediate action should be taken to control the outbreak and minimize further spread?
In a large equine practice, a cluster of horses suddenly develop neurological signs, including fever, ataxia, and urinary incontinence. Equine Herpes Myeloencephalitis (EHM) is suspected. What immediate action should be taken to control the outbreak and minimize further spread?
Following a confirmed outbreak of Equine Herpes Myeloencephalitis (EHM) in a boarding facility, what is the most critical long-term biosecurity measure to implement to prevent future outbreaks?
Following a confirmed outbreak of Equine Herpes Myeloencephalitis (EHM) in a boarding facility, what is the most critical long-term biosecurity measure to implement to prevent future outbreaks?
A young horse presents with symmetrical ataxia and paresis, worse in the hind limbs. Serum vitamin E levels are within the marginal range. To further investigate a possible diagnosis of Equine Degenerative Myelopathy (EDM), what additional diagnostic step would be most informative?
A young horse presents with symmetrical ataxia and paresis, worse in the hind limbs. Serum vitamin E levels are within the marginal range. To further investigate a possible diagnosis of Equine Degenerative Myelopathy (EDM), what additional diagnostic step would be most informative?
Considering the limitations of antemortem diagnostics for Equine Degenerative Myelopathy (EDM), which combination of clinical findings and diagnostic results would most strongly suggest EDM?
Considering the limitations of antemortem diagnostics for Equine Degenerative Myelopathy (EDM), which combination of clinical findings and diagnostic results would most strongly suggest EDM?
A horse diagnosed with Equine Protozoal Myeloencephalitis (EPM) initially responds well to treatment but relapses several months later with similar neurological deficits. What factor is most likely contributing to the relapse?
A horse diagnosed with Equine Protozoal Myeloencephalitis (EPM) initially responds well to treatment but relapses several months later with similar neurological deficits. What factor is most likely contributing to the relapse?
What is the most accurate statement regarding the impact of vaccination on Equine Herpes Myeloencephalitis (EHM) outbreaks?
What is the most accurate statement regarding the impact of vaccination on Equine Herpes Myeloencephalitis (EHM) outbreaks?
Based on current understanding of Equine Degenerative Myelopathy (EDM), which of the following management strategies is most likely to improve long-term outcomes in affected horses?
Based on current understanding of Equine Degenerative Myelopathy (EDM), which of the following management strategies is most likely to improve long-term outcomes in affected horses?
A horse presents with acute onset of fever, severe ataxia, and urine dribbling. Cerebrospinal fluid (CSF) analysis reveals xanthochromia and elevated protein levels, with a normal cell count. Which of the following is the most likely diagnosis?
A horse presents with acute onset of fever, severe ataxia, and urine dribbling. Cerebrospinal fluid (CSF) analysis reveals xanthochromia and elevated protein levels, with a normal cell count. Which of the following is the most likely diagnosis?
In comparing Equine Protozoal Myeloencephalitis (EPM) and Equine Herpes Myeloencephalitis (EHM), which statement best differentiates the typical clinical presentation of these diseases?
In comparing Equine Protozoal Myeloencephalitis (EPM) and Equine Herpes Myeloencephalitis (EHM), which statement best differentiates the typical clinical presentation of these diseases?
What is the significance of albuminocytologic dissociation in cerebrospinal fluid (CSF) analysis in cases of Equine Herpes Myeloencephalitis (EHM)?
What is the significance of albuminocytologic dissociation in cerebrospinal fluid (CSF) analysis in cases of Equine Herpes Myeloencephalitis (EHM)?
Which factor is least likely to impact the efficacy of treatment for Equine Protozoal Myeloencephalitis (EPM)?
Which factor is least likely to impact the efficacy of treatment for Equine Protozoal Myeloencephalitis (EPM)?
In a region with high Sarcocystis neurona seroprevalence, what result would give the highest confidence that a horse's neurological issues are due to EPM?
In a region with high Sarcocystis neurona seroprevalence, what result would give the highest confidence that a horse's neurological issues are due to EPM?
Which of the following scenarios poses the highest risk for the development of Equine Herpes Myeloencephalitis (EHM) within a closed herd of horses?
Which of the following scenarios poses the highest risk for the development of Equine Herpes Myeloencephalitis (EHM) within a closed herd of horses?
What is the primary reason behind the recommendation to administer vegetable oil alongside ponazuril when treating Equine Protozoal Myeloencephalitis (EPM)?
What is the primary reason behind the recommendation to administer vegetable oil alongside ponazuril when treating Equine Protozoal Myeloencephalitis (EPM)?
Which diagnostic result would be most indicative of EHV-1 as the causative agent in a horse displaying acute neurological signs?
Which diagnostic result would be most indicative of EHV-1 as the causative agent in a horse displaying acute neurological signs?
What is the most likely implication of a negative Western blot test for Sarcocystis neurona in a horse displaying neurological signs consistent with Equine Protozoal Myeloencephalitis (EPM)?
What is the most likely implication of a negative Western blot test for Sarcocystis neurona in a horse displaying neurological signs consistent with Equine Protozoal Myeloencephalitis (EPM)?
Which of the following statements most accurately describes the role of the opossum in the transmission of Equine Protozoal Myeloencephalitis (EPM)?
Which of the following statements most accurately describes the role of the opossum in the transmission of Equine Protozoal Myeloencephalitis (EPM)?
Considering the clinical presentations and diagnostic challenges, what is the most appropriate approach to differentiating between Equine Degenerative Myelopathy (EDM) and Cervical Vertebral Stenotic Myelopathy (CVSM) in a young horse?
Considering the clinical presentations and diagnostic challenges, what is the most appropriate approach to differentiating between Equine Degenerative Myelopathy (EDM) and Cervical Vertebral Stenotic Myelopathy (CVSM) in a young horse?
In the context of Equine Herpes Myeloencephalitis (EHM), what is the primary rationale for using valacyclovir?
In the context of Equine Herpes Myeloencephalitis (EHM), what is the primary rationale for using valacyclovir?
A horse with confirmed Equine Protozoal Myeloencephalitis (EPM) is being treated with ponazuril. What adjunctive therapy would provide NO benefit?
A horse with confirmed Equine Protozoal Myeloencephalitis (EPM) is being treated with ponazuril. What adjunctive therapy would provide NO benefit?
Which statement accurately describes the role of genetic predisposition in Equine Degenerative Myelopathy (EDM)?
Which statement accurately describes the role of genetic predisposition in Equine Degenerative Myelopathy (EDM)?
Which of the following best describes the diagnostic approach for Equine Degenerative Myelopathy (EDM)?
Which of the following best describes the diagnostic approach for Equine Degenerative Myelopathy (EDM)?
During an Equine Herpes Myeloencephalitis (EHM) outbreak, which action poses the highest risk for spreading the virus?
During an Equine Herpes Myeloencephalitis (EHM) outbreak, which action poses the highest risk for spreading the virus?
When considering treatment options for a horse diagnosed with Equine Protozoal Myeloencephalitis, which additional immune modulating therapy would be least benificial if using traditionally effective approaches?
When considering treatment options for a horse diagnosed with Equine Protozoal Myeloencephalitis, which additional immune modulating therapy would be least benificial if using traditionally effective approaches?
With regards to the EPM parasite Sarcocystis neurona, where is the most common lesion location?
With regards to the EPM parasite Sarcocystis neurona, where is the most common lesion location?
Flashcards
Equine Degenerative Myelopathy (EDM)
Equine Degenerative Myelopathy (EDM)
A neurological disease in horses characterized by neuronal degeneration.
Spheroids
Spheroids
Degenerating neurons and axons that are swollen.
EDM location in spinal cord
EDM location in spinal cord
Dorsal and ventral spinocerebellar tracts of cervicothoracic spinal cord.
EDM Pathogenesis
EDM Pathogenesis
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EDM Onset
EDM Onset
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EDM Predisposed Breeds
EDM Predisposed Breeds
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EDM Clinical Signs
EDM Clinical Signs
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EDM Diagnosis
EDM Diagnosis
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Treatment of EDM with Vitamin E
Treatment of EDM with Vitamin E
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Key factors of EDM
Key factors of EDM
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Equine Protozoal Myelitis (EPM)
Equine Protozoal Myelitis (EPM)
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Intermediate hosts for EPM
Intermediate hosts for EPM
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EPM Signalment
EPM Signalment
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EPM Prevalence
EPM Prevalence
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EPM Season of Development
EPM Season of Development
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EPM Neurologic Signs
EPM Neurologic Signs
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Location of EPM lesions
Location of EPM lesions
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CSF Collection for EPM
CSF Collection for EPM
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EPM Diagnosis
EPM Diagnosis
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Serology for EPM
Serology for EPM
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Normal CSF Cytology
Normal CSF Cytology
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Surface antigen ELISA for EPM
Surface antigen ELISA for EPM
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EPM Treatment
EPM Treatment
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Ponazuril Use
Ponazuril Use
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ReBalance
ReBalance
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EPM Treatment Efficacy
EPM Treatment Efficacy
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Clinical Management of EPM
Clinical Management of EPM
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EPM Prevention
EPM Prevention
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Equine Herpes Myeloencephalitis (EHM)
Equine Herpes Myeloencephalitis (EHM)
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EHM Signalment
EHM Signalment
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Gene Sequence EHM
Gene Sequence EHM
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EHM Virulence
EHM Virulence
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EHV-1 DNA ORF 30
EHV-1 DNA ORF 30
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EHV-1 Paralysis vs Abortion
EHV-1 Paralysis vs Abortion
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EHM Clinical Signs
EHM Clinical Signs
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EHM Specific Clinical Signs
EHM Specific Clinical Signs
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EHM Diagnosis
EHM Diagnosis
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EHM Treatment
EHM Treatment
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EHM Drug Treatment
EHM Drug Treatment
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EHM Carriers
EHM Carriers
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EHM Prevention
EHM Prevention
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Study Notes
Equine Degenerative Myelopathy (EDM)
- EDM involves neuronal degeneration
- EDM is on a continuum of Neuroaxonal Dystrophy (NAD)
- Dystrophic neurons and axons have spheroids, which are swollen axons
- In NAD, brainstem nuclei are affected
- In EDM, the dorsal and ventral spinocerebellar tracts of the cervicothoracic spinal cord are affected
- EDM causes axonal necrosis and demyelination
- The exact cause and underlying mechanisms are unknown
- EDM occurs in genetically predisposed individuals with vitamin E deficiency within their first year
- Vitamin E deficiency is associated with oxidation of central nervous system membrane lipids
- Clinical signs typically begin in the first year
- Morgan, Appaloosa, and Lusitano breeds are more prone to EDM
- Standardbred, Paso Finos, Norwegian Fjord, Arabian, Welsh pony, Haflinger, and Quarter Horse breeds may also be affected
- Symmetric ataxia and paresis occur in the trunk and limbs
- EDM is worse in the pelvic limbs
- Affected horses exhibit a wide-based stance and gait, spasticity, and a 2-beat lateral "pacing" walk
- Long spinal reflexes are reduced or absent and the cutaneous trunci is affected
- It is localized in the spinal cord, specifically in the cervical vertebrae; may also be diffuse
- No specific antemortem test exists
- it is diagnosed through exclusion of other conditions
- Cerebrospinal fluid (CSF) analysis, cervical vertebral radiographs, and myelogram are normal
- Postmortem necropsy reveals lesions in the brainstem, cervical, and thoracic spinal cord
- A serum vitamin E level of >4 µg/mL (or >400 µg/dL) is considered normal for supporting neurological and muscular function
- A serum vitamin E level of 2-4 µg/mL (200-400 µg/dL) indicates marginal/borderline status and a risk of deficiency if persistent or combined with stressors
- A serum vitamin E level of <2 µg/mL (or <200 µg/dL) indicates vitamin E deficiency and an increased risk for neurologic conditions like EDM
- Vitamin E supplementation is used as treatment.
- Natural Vitamin E is needed for uptake by the liver
- Administer 10-20 IU/kg PO daily (5,000-10,000 IU)
- Monitor serum vitamin E levels.
- Prognosis for recovery is guarded, even with early treatment
- Vitamin E supplementation may serve as preventative for predisposed horses
Equine Protozoal Myelitis (EPM)
- The term was created in the mid 1970's
- The causative agent Sarcocystis neurona was cultured from an affected horse's spinal cord in 1991
- Its life cycle involves the opossum as the definitive host
- Intermediate hosts include raccoons, armadillos, skunks and cats
- The related protozoa Neospora hughesi can also cause EPM-like signs
- All breeds have been reported
- 62% of cases are in horses under 4 years of age
- 20% cases are in horses over 8 years of age
- Peak incidence occurs from 15 months to 5 years
- Standardbreds, Thoroughbreds, and Quarter Horses are common breeds
- Overall seroprevalence from US submissions is around 60%
- Seroprevalence ranges from 31-85% in Arizona/Arkansas
- Seroprevalence is lower in the western and far northeast states, and higher in the southeastern central states
- States with moderate seroprevalence (22-42%) may test negative for EPM
- States with higher seroprevalence may still have up to 20% test negative cases.
- The western blot is a useful tool
- A negative test helps rule out S. neurona caused EPM
- EPM has a predilection in the fall and spring/summer
- It presents with spinal cord lesions in 85% of cases, cortical and brainstem lesions in 15%
- Multifocal and asymmetric signs are highly suspect for EPM
- Focal muscle atrophy occurs
- Disease progression may be insidious and progressive, acute, or static
- Serology only determines exposure
- It can help refine the differential diagnosis.
- CSF analysis is more accurate for disease likelihood
- collect CSF samples as close to lesion as possible at the AO, C1-2, and LS locations
- Increasing test sensitivity is gained via an increased concentration of antibodies
- Normal CSF cytology shows clear, colorless fluid
- A cell count of <5-8/uL
- Protein concentration of <50-80 mg/dL
- Glucose at 80% of circulating levels
- Commercial testing exists for antiprotozoal antibodies of S. neurona and N. hughesi
- Testing can be performed on serum, CSF, or both
- Western blot is qualitative and examines antibodies against merozoite lysate
- Indirect fluorescent antibody test is quantitative and examines antibodies against culture-grown merozoites. The titer is a poor predictor and has low specificity
- Surface antigen ELISAs detect SnSAG 2 and SnSAG 4/3 antibodies in serum and CSF
- A serum to CSF ratio provides the highest diagnostic accuracy
- A serum:CSF <100 indicates a positive test for EPM
- FDA approved treatments: Benzeneacetonitrile (triazine) medications
- They target the parasite's apicoplast organelle
- Can use Ponazuril at 15 mg/kg PO loading, then 5 mg/kg PO daily x 28 days
- Ponazuril should be administered with vegetable oil to enhance absorption
- Diclazuril can be used with no loading dose: label 1 mg/kg PO daily x 28 days
- ReBalance® is FDA approved, includes pyrimethamine and sulfadiazine, and blocks protozoal folate synthesis
- Administer by PYR 1 mg/kg PO daily and SDZ 20 mg/kg PO daily on an empty stomach
- FDA-approved compounds have a 62-67% response rate
- Treatments improve at least 1 grade or result in negative antibody tests in serum and CSF
- Triazines have minimal toxicity, while pyrimethamine is not recommended in broodmares
- Treat for 6-8 weeks minimum
- NSAIDs may be used for the first 5-7 days of therapy: Flunixin meglumine 0.5-1.1 mg/kg IV/PO and Phenylbutazone 2.2-4.4 mg/kg IV/PO
- Corticosteroids can be employed for rapidly progressive, recumbent or cortical manifestations
- Antioxidant therapy with DMSO: 0.5-1 g/kg/day for 3-6 days alongside Vitamin E at 1000-10,000 IU can be beneficial
- Immunostimulant therapy with Propionibacterium and Levamisole can be used
- Demonstrate improvement – 60-70%
- One grade improvement occurs with medications
- 10-20% complete recovery can occur
- Neurologically normal return occurs less than 20%
- Recumbency and muscle mass loss are associated with a poor prognosis
- Relapse occurs in 10% of cases
- Deficits are similar to previous episodes
- Symptoms can return months to years after discontinuation
- Response to treatment is worse than the first episode
- Relapses require more aggressive treatment and preventative maintenance therapy.
- To prevent EPM, avoid contact with opossums and protect food/grain
- FDA-approved drugs can be used strategically
- Ponazuril can be used at 2.5-5.0 mg/kg PO daily before exposure or 20 mg/kg PO every 7 days.
- Diclazuril at 0.5 mg/kg PO daily.
Equine Herpes Myelitis (EHM)
- Equine Herpesvirus (EHV) causes rhinopneumonitis and can manifest in respiratory, abortion/perinatal, neurologic diseases, and chorioretinitis
- EHV has caused the FEI to shutdown international events due to the EHV-1 outbreak; it is a common DNA virus
- No gender, breed, geographic, or seasonal predilection
- Aged (>20 years) horses are more susceptible
- Fever presents 5 to 7 days prior to neurologic signs
- Unique EHV-1 strains can remain abortogenic but show single AA substitution
- Unique EHV-1 strains includes a DNA polymerase shift
- Position 752: asparagine is replaced with aspartic acid
- Gene sequence determines pathogenicity
- Ab4 is high virulence and V592 is low virulence
- Sequence variation at ORF30 for viral DNA polymerase is associated with paralytic viruses
- Confirmation of EHV-1 aids in clinical management
- Mutation is associated with neurologic disease; interpret with caution
- 14-24% of EHV-1 isolates in horses with EHM do not have mutation
- When infected with the neuropathic strain, the OR of neurologic disease is 162 x greater
- EHV is evolving in virulence and behavior; USDA designation: Potentially Emerging
- Clinical signs present with symmetric weakness and ataxia
- Ascending myelitis occurs from Hind >>>> fore
- Poor tail tone is a symptom
- Urine dribbling and prolapsed penis are also symptoms
EHM CSF Analysis
- Xanthochromia
- Total protein > 150 mg/dl
- Normal cell count (<5-8 cells/µL)
- Albuminocytologic dissociation
- High protein
- Normal cell concentration
- CSF titers - unreliable
- A diagnosis of neuropathic EHV 1 involves a Quantitative PCR (qPCR)
- This can be done on CSF, nasal secretions, pharyngeal swab, or buffy coat
- Virus isolation
- Treatment includes supportive care such as a sling, good footing and a urinary catheter
- Anti-inflammatory drugs like NSAIDs (flunixin meglumine) are used at 0.5-1.1 mg/g PO / IV 5-10 days
- As well as CCS (dexamethasone) at 0.05-0.1 mg/kg PO / IV 1-3 days
- Valacyclovir is used at 30-40 mg/kg PO TID to BID x 7-10 days
- A prognosis for recovery is good if standing
- Once infected, patients are carriers for life due to latency
- The best strategy to prevent is BIOSECURITY
- High antigen EHV-1 vaccines are recommended, but currently no approved vaccine exists
- Vaccination may reduce shedding
- Isolate affected horses for 21-28 days after resolution of signs or until PCR of nasal swab is negative
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