Podcast
Questions and Answers
Which of the following should always be examined in an animal with neurological disease?
Which of the following should always be examined in an animal with neurological disease?
- Digestive system
- Central nervous system (correct)
- Peripheral nervous system
- Respiratory system
The spinal cord should only be examined if there is a history of paresis or paralysis.
The spinal cord should only be examined if there is a history of paresis or paralysis.
False (B)
What solution is optimal for immersion fixation of the brain and spinal cord?
What solution is optimal for immersion fixation of the brain and spinal cord?
10% buffered formalin solution
Neurons are highly specialized postmitotic cells that are very susceptible to __________ and toxic substances.
Neurons are highly specialized postmitotic cells that are very susceptible to __________ and toxic substances.
What is the primary reason for the serious consequences of tissue compression in the nervous system?
What is the primary reason for the serious consequences of tissue compression in the nervous system?
Match the types of cells in the nervous system with their functions:
Match the types of cells in the nervous system with their functions:
Autolysis in the brain and spinal cord occurs at a slow rate due to their high lipid content.
Autolysis in the brain and spinal cord occurs at a slow rate due to their high lipid content.
What should be worn when handling tissues of rabies suspects?
What should be worn when handling tissues of rabies suspects?
What is the main cause of cervical vertebral stenotic myelopathy (CVSM) in horses?
What is the main cause of cervical vertebral stenotic myelopathy (CVSM) in horses?
Intervertebral disk disease primarily affects cats and dogs.
Intervertebral disk disease primarily affects cats and dogs.
Name the two types of herniations associated with intervertebral disk disease (IVDD).
Name the two types of herniations associated with intervertebral disk disease (IVDD).
Cervical static stenosis affects horses between the ages of _______ to _______ years.
Cervical static stenosis affects horses between the ages of _______ to _______ years.
Match the types of nerve injuries with their descriptions:
Match the types of nerve injuries with their descriptions:
Which type of herniation occurs without a history of trauma and may involve extrusion of degenerated disc material?
Which type of herniation occurs without a history of trauma and may involve extrusion of degenerated disc material?
Teratogens mainly act during the first third of pregnancy during the critical period of morphogenesis.
Teratogens mainly act during the first third of pregnancy during the critical period of morphogenesis.
What age range does cervical vertebral instability (dynamic stenosis) affect in horses?
What age range does cervical vertebral instability (dynamic stenosis) affect in horses?
What function do interfascicular oligodendrocytes primarily serve?
What function do interfascicular oligodendrocytes primarily serve?
Astrocytes are the least numerous cell type in the CNS.
Astrocytes are the least numerous cell type in the CNS.
What are the primary components transported by the fast axonal anterograde transport system?
What are the primary components transported by the fast axonal anterograde transport system?
The brain's protective membranes are known as the _____ membranes.
The brain's protective membranes are known as the _____ membranes.
Match the following cell types with their primary function:
Match the following cell types with their primary function:
Which structure regulates the flow of cerebrospinal fluid?
Which structure regulates the flow of cerebrospinal fluid?
Schwann cells myelinate central nervous system nerves.
Schwann cells myelinate central nervous system nerves.
What is the primary role of microglia in the CNS?
What is the primary role of microglia in the CNS?
Cerebrospinal fluid (CSF) is produced by the _____ choroid plexus.
Cerebrospinal fluid (CSF) is produced by the _____ choroid plexus.
Match the following axonal transport types with their description:
Match the following axonal transport types with their description:
What can cause axonopathies?
What can cause axonopathies?
Nerve fibers in the PNS can regenerate under certain circumstances.
Nerve fibers in the PNS can regenerate under certain circumstances.
What is the main function of the blood-brain barrier?
What is the main function of the blood-brain barrier?
What is one common cause of acute neuronal necrosis?
What is one common cause of acute neuronal necrosis?
The _____ layer is composed of strong dense collagenous tissue.
The _____ layer is composed of strong dense collagenous tissue.
What happens to neurons during cessation of blood flow?
What happens to neurons during cessation of blood flow?
Chromatolysis is characterized by cell swelling and dispersal of Nissl substance.
Chromatolysis is characterized by cell swelling and dispersal of Nissl substance.
What is the term for the process of axonal degeneration with secondary myelin loss?
What is the term for the process of axonal degeneration with secondary myelin loss?
The accumulation of _____ in aging neurons is known as lipofuscin.
The accumulation of _____ in aging neurons is known as lipofuscin.
Match the following neuronal responses to their descriptions:
Match the following neuronal responses to their descriptions:
Which of the following represents a feature of acute degenerative change in neurons?
Which of the following represents a feature of acute degenerative change in neurons?
Excitotoxicity can be caused by the excessive stimulation of neurons by inhibitory neurotransmitters.
Excitotoxicity can be caused by the excessive stimulation of neurons by inhibitory neurotransmitters.
What type of neuronal injury may result from heavy metal intoxication?
What type of neuronal injury may result from heavy metal intoxication?
Activation of _____ in response to neuronal injury leads to the removal of necrotic neurons.
Activation of _____ in response to neuronal injury leads to the removal of necrotic neurons.
Which process leads to the fragmentation of the axon following an injury?
Which process leads to the fragmentation of the axon following an injury?
Astrogliosis refers to the decrease in size and number of astrocytes in the brain following injury.
Astrogliosis refers to the decrease in size and number of astrocytes in the brain following injury.
Name a type of neuron damage associated with viral diseases.
Name a type of neuron damage associated with viral diseases.
In the central nervous system, degeneration of myelin sheaths is observed in _____ degeneration.
In the central nervous system, degeneration of myelin sheaths is observed in _____ degeneration.
Which of the following is a feature of chronic neuronal necrosis?
Which of the following is a feature of chronic neuronal necrosis?
Which of the following diseases is associated with immunological destruction in animals?
Which of the following diseases is associated with immunological destruction in animals?
Cytotoxic edema is primarily a result of vascular injury and breakdown of the blood-brain barrier.
Cytotoxic edema is primarily a result of vascular injury and breakdown of the blood-brain barrier.
What is the common response of ependymal and choroid plexus epithelial cells to injury?
What is the common response of ependymal and choroid plexus epithelial cells to injury?
The term for inflammation of the meninges is called __________.
The term for inflammation of the meninges is called __________.
Which type of edema is most commonly observed in the CNS of animals?
Which type of edema is most commonly observed in the CNS of animals?
Ependymitis is caused primarily by direct physical trauma.
Ependymitis is caused primarily by direct physical trauma.
What are Gitter cells?
What are Gitter cells?
The predominant injury pattern from traumatic lesions is typically __________.
The predominant injury pattern from traumatic lesions is typically __________.
Match the following conditions with their corresponding characteristics:
Match the following conditions with their corresponding characteristics:
What can result from ischemic lesions in the CNS?
What can result from ischemic lesions in the CNS?
Hydrocephalus refers to inflammation of the brain.
Hydrocephalus refers to inflammation of the brain.
What is a common consequence of severe endothelial injury in the CNS?
What is a common consequence of severe endothelial injury in the CNS?
Interstitial edema occurs due to elevated ventricular __________ pressure.
Interstitial edema occurs due to elevated ventricular __________ pressure.
Which condition is characterized by the accumulation of fibrocartilage in spinal arteries?
Which condition is characterized by the accumulation of fibrocartilage in spinal arteries?
Concussions result in permanent structural damage to the brain.
Concussions result in permanent structural damage to the brain.
What is the primary cause of acquired hydrocephalus in animals?
What is the primary cause of acquired hydrocephalus in animals?
External hydrocephalus refers to fluid accumulation within the ventricular system.
External hydrocephalus refers to fluid accumulation within the ventricular system.
Name one viral infection that can cause cerebellar hypoplasia in domestic animals.
Name one viral infection that can cause cerebellar hypoplasia in domestic animals.
Hydrocephalus is characterized by the abnormal accumulation of __________ fluid.
Hydrocephalus is characterized by the abnormal accumulation of __________ fluid.
Match the following terms with their definitions:
Match the following terms with their definitions:
Which of the following viruses is responsible for causing 'hairy-shaker' lambs?
Which of the following viruses is responsible for causing 'hairy-shaker' lambs?
Abscesses in the nervous system are primarily caused by viral infections.
Abscesses in the nervous system are primarily caused by viral infections.
What type of hydrocephalus involves bilateral and symmetrical dilation of the ventricular system?
What type of hydrocephalus involves bilateral and symmetrical dilation of the ventricular system?
Certain bacterial infections, like those caused by __________, can lead to neonatal bacterial suppurative meningitis.
Certain bacterial infections, like those caused by __________, can lead to neonatal bacterial suppurative meningitis.
What is a common complication of poorly preserved silage in ruminants?
What is a common complication of poorly preserved silage in ruminants?
Ependymitis refers to the inflammation of the meninges.
Ependymitis refers to the inflammation of the meninges.
Which condition affects the brainstem and is associated with the consumption of poorly preserved silage?
Which condition affects the brainstem and is associated with the consumption of poorly preserved silage?
The inflammation of the meninges that involves the pia-arachnoid is called __________.
The inflammation of the meninges that involves the pia-arachnoid is called __________.
Match the bacterial disease with its primary outcome:
Match the bacterial disease with its primary outcome:
What is the primary cause of equine protozoal myeloencephalitis (EPM)?
What is the primary cause of equine protozoal myeloencephalitis (EPM)?
Vaccination of pregnant dogs poses no risk to their puppies.
Vaccination of pregnant dogs poses no risk to their puppies.
Name a definitive host for Sarcocystis neurona.
Name a definitive host for Sarcocystis neurona.
Dogs shed oocysts in their __________ after being infected with Neospora caninum.
Dogs shed oocysts in their __________ after being infected with Neospora caninum.
Match the following diseases with their associated agents:
Match the following diseases with their associated agents:
Which clinical sign is commonly associated with EPM?
Which clinical sign is commonly associated with EPM?
What is a common clinical sign of viral infections affecting the central nervous system?
What is a common clinical sign of viral infections affecting the central nervous system?
Viral CNS infections usually cause the formation of pus in the brain.
Viral CNS infections usually cause the formation of pus in the brain.
The lesions in TSEs are primarily grossly visible in the brain.
The lesions in TSEs are primarily grossly visible in the brain.
What type of lesions characterize EPM in severe cases?
What type of lesions characterize EPM in severe cases?
Which virus is responsible for causing canine herpesviral encephalitis?
Which virus is responsible for causing canine herpesviral encephalitis?
The presence of _______________ is indicative of rabies in infected neural tissues.
The presence of _______________ is indicative of rabies in infected neural tissues.
Neosporosis is an important cause of __________ in bovines.
Neosporosis is an important cause of __________ in bovines.
Match the following viruses with their associated diseases:
Match the following viruses with their associated diseases:
What is the causative agent of toxoplasmosis?
What is the causative agent of toxoplasmosis?
Prion diseases are characterized by inflammatory changes in the brain.
Prion diseases are characterized by inflammatory changes in the brain.
Which of the following is NOT a common effect of herpesvirus infections in the CNS?
Which of the following is NOT a common effect of herpesvirus infections in the CNS?
Which of the following is a common clinical sign of hepatic encephalopathy?
Which of the following is a common clinical sign of hepatic encephalopathy?
The incubation period for rabies infections can last for several months.
The incubation period for rabies infections can last for several months.
Copper deficiency causes congenital defects in lambs.
Copper deficiency causes congenital defects in lambs.
What histological change is a hallmark of transmissible spongiform encephalopathies?
What histological change is a hallmark of transmissible spongiform encephalopathies?
The primary route for Neospora caninum infection in cattle is through __________.
The primary route for Neospora caninum infection in cattle is through __________.
What is the primary cause of equine laryngeal hemiplegia?
What is the primary cause of equine laryngeal hemiplegia?
What is the primary target tissue in malignant catarrhal fever?
What is the primary target tissue in malignant catarrhal fever?
Match the following mycotic diseases with their associated characteristics:
Match the following mycotic diseases with their associated characteristics:
Perennial rye-grass staggers is caused by the fungus __________.
Perennial rye-grass staggers is caused by the fungus __________.
Canine distemper virus spreads to the brain and infects ________ and ________ cells.
Canine distemper virus spreads to the brain and infects ________ and ________ cells.
Match the following CNS tumors with their characteristics:
Match the following CNS tumors with their characteristics:
Which condition is characterized by widespread necrotizing vasculitis due to endothelial cell infection?
Which condition is characterized by widespread necrotizing vasculitis due to endothelial cell infection?
The rabies virus has a short clinical course lasting only a few hours.
The rabies virus has a short clinical course lasting only a few hours.
Which of these is a histopathological finding in hepatic encephalopathy?
Which of these is a histopathological finding in hepatic encephalopathy?
Oligodendrogliomas are primarily reported in cats.
Oligodendrogliomas are primarily reported in cats.
Identify one primary mode through which neurotropic viruses enter the CNS.
Identify one primary mode through which neurotropic viruses enter the CNS.
In horses, spinal cord involvement in rabies is more common than _______ involvement.
In horses, spinal cord involvement in rabies is more common than _______ involvement.
What is the typical recovery time for animals affected by perennial rye-grass staggers after removal from toxic pasture?
What is the typical recovery time for animals affected by perennial rye-grass staggers after removal from toxic pasture?
Match the term with its definition.
Match the term with its definition.
Histopathological findings in copper deficiency associated with swayback include __________ in the spinal cord.
Histopathological findings in copper deficiency associated with swayback include __________ in the spinal cord.
Which type of nervous system tumor originates from the nervous system itself?
Which type of nervous system tumor originates from the nervous system itself?
What is a common cause of polioencephalomalacia (PEM) in ruminants?
What is a common cause of polioencephalomalacia (PEM) in ruminants?
Lead poisoning is rarely observed in swine.
Lead poisoning is rarely observed in swine.
What is the primary mycotoxin responsible for mycotoxic leukoencephalomalacia in horses?
What is the primary mycotoxin responsible for mycotoxic leukoencephalomalacia in horses?
The disease characterized by tail paralysis and urinary incontinence in horses is called __________.
The disease characterized by tail paralysis and urinary incontinence in horses is called __________.
Match each condition to its characteristic feature:
Match each condition to its characteristic feature:
What clinical signs are associated with salt poisoning in livestock?
What clinical signs are associated with salt poisoning in livestock?
Focal symmetrical encephalomalacia is primarily associated with high starch diets in sheep and cattle.
Focal symmetrical encephalomalacia is primarily associated with high starch diets in sheep and cattle.
What type of inflammation is typically observed in chronic cases of Polyneuritis equi?
What type of inflammation is typically observed in chronic cases of Polyneuritis equi?
The mycotoxin responsible for neurological impairment in horses due to mouldy corn is __________.
The mycotoxin responsible for neurological impairment in horses due to mouldy corn is __________.
What is a common gross observation in the brains affected by gatti?
What is a common gross observation in the brains affected by gatti?
Malacia refers to the hardening of tissue in the CNS.
Malacia refers to the hardening of tissue in the CNS.
What are the principal clinical signs of polioencephalomalacia in ruminants?
What are the principal clinical signs of polioencephalomalacia in ruminants?
Match each disease to its respective animal group:
Match each disease to its respective animal group:
Oedema, increased pressure, and necrosis in the brain can occur after regaining access to water following dehydration from salt poisoning.
Oedema, increased pressure, and necrosis in the brain can occur after regaining access to water following dehydration from salt poisoning.
What is the most abundant protein found in normal cerebrospinal fluid (CSF)?
What is the most abundant protein found in normal cerebrospinal fluid (CSF)?
Increased protein levels in CSF are always associated with an increase in cellularity.
Increased protein levels in CSF are always associated with an increase in cellularity.
What is the maximum typical total nucleated cell count per microliter of CSF in dogs?
What is the maximum typical total nucleated cell count per microliter of CSF in dogs?
Turbidity in cerebrospinal fluid can be caused by increased numbers of __________ and/or __________.
Turbidity in cerebrospinal fluid can be caused by increased numbers of __________ and/or __________.
Match the pleocytosis type with its common cause:
Match the pleocytosis type with its common cause:
What method is commonly used to prepare cells for cytological evaluation of CSF?
What method is commonly used to prepare cells for cytological evaluation of CSF?
Normal CSF contains erythrocytes in significant quantities.
Normal CSF contains erythrocytes in significant quantities.
What preliminary screening test is suggested for estimating CSF protein concentration?
What preliminary screening test is suggested for estimating CSF protein concentration?
The Pandy test indicates the presence of increased __________ concentration in CSF.
The Pandy test indicates the presence of increased __________ concentration in CSF.
Which of the following is a common method for identifying bacterial meningitis in cloudy CSF?
Which of the following is a common method for identifying bacterial meningitis in cloudy CSF?
What type of tumors are most commonly benign and associated with the meninges?
What type of tumors are most commonly benign and associated with the meninges?
Choroid plexus tumors can only be carcinomas, due to their cellular characteristics.
Choroid plexus tumors can only be carcinomas, due to their cellular characteristics.
Which breed of dog shows a significant predisposition to choroid plexus tumors?
Which breed of dog shows a significant predisposition to choroid plexus tumors?
Degenerative changes in the choroid plexus often lead to the formation of __________ granulomas.
Degenerative changes in the choroid plexus often lead to the formation of __________ granulomas.
Match the following types of CNS tumors with their characteristics:
Match the following types of CNS tumors with their characteristics:
Which of the following is a characteristic of cerebrospinal fluid (CSF)?
Which of the following is a characteristic of cerebrospinal fluid (CSF)?
Pleocytosis refers to a decrease in total nucleated cell count in cerebrospinal fluid.
Pleocytosis refers to a decrease in total nucleated cell count in cerebrospinal fluid.
What is the main function of cerebrospinal fluid?
What is the main function of cerebrospinal fluid?
The normal total nucleated cell count in CSF for dogs is between __________ cells/μl.
The normal total nucleated cell count in CSF for dogs is between __________ cells/μl.
Match the following CSF abnormalities with their possible indications:
Match the following CSF abnormalities with their possible indications:
Which of the following is a potential complication when collecting CSF from a patient with cranial trauma?
Which of the following is a potential complication when collecting CSF from a patient with cranial trauma?
Cerebrospinal fluid can be collected safely from any site in the body.
Cerebrospinal fluid can be collected safely from any site in the body.
What is the principal protein found in normal cerebrospinal fluid?
What is the principal protein found in normal cerebrospinal fluid?
The reference range for protein concentration in CSF for dogs is __________ mg/dL.
The reference range for protein concentration in CSF for dogs is __________ mg/dL.
Which type of hematopoietic tumor may primarily originate in the central nervous system?
Which type of hematopoietic tumor may primarily originate in the central nervous system?
Study Notes
Postmortem Examination of the Nervous System
- Central nervous system (CNS) examination is mandatory for animals with neurological diseases or inconclusive major organ lesions.
- Spinal cord and canal examination is essential if there is evidence of paresis or paralysis.
- Focused CNS examination is more efficient when specific lesion locations are identified through previous diagnostics like MRI.
- When a specific lesion cannot be localized, representative sampling from multiple anatomical regions is necessary.
- Detailed inspections of the brain include assessing cerebrum and cerebellum size, malformations, symmetry, swellings, and meningeal alterations.
- Rapid autolysis occurs in brain and spinal cord due to high lipid content; immersion fixation in 10% buffered formalin for 5-10 days is recommended.
- Handle rabies or zoonotic disease suspects with caution and appropriate protective gear to prevent exposure.
Pathology of the Nervous System
- Anatomy and histology of the CNS limit room for expansion in disease states, making even slight compression hazardous.
- Neuronal cells are highly specialized and vulnerable to hypoxia and toxins, featuring distinct structures (cell body, dendrites, axon) and functions.
- Various CNS cells are involved in pathology: neurons, glia, ependymal cells, meninges, Schwann cells, endothelial cells, and pericytes.
Neurons
- Neurons are large, specialized postmitotic cells with significant energy requirements but limited oxygen reserves; they cannot regenerate.
- Neurons are organized into functional groups for efficiency and communication.
- Transport systems include fast anterograde and retrograde systems and a slow anterograde system for essential proteins, responsible for injury responses termed axonopathies.
Astrocytes, Oligodendrocytes, Microglia
- Astrocytes act as interstitial cells, providing support, forming the blood-brain barrier, and aiding in repair.
- Oligodendrocytes are crucial for CNS myelination with two types: interfascicular (myelin production) and satellite (environment regulation).
- Microglia serve as phagocytes, playing essential roles in immune response and tissue integrity.
Cerebrospinal Fluid and Meninges
- Cerebrospinal fluid (CSF) is secreted by the choroid plexus, delivering nutrients, removing waste, and acting as shock protection.
- The meninges consist of three layers: dura (strong collagen), arachnoid (multi-layered), and pia mater (vascularized, thin layer).
Blood-Brain Barrier
- Formed by tight junctions of endothelial cells, basement membranes, and astrocyte foot processes, it protects the CNS environment.
Understanding CNS Injuries
- Varying vulnerability to injury among CNS cells: neurons (highest), oligodendroglia (moderate), astrocytes (lower), microglia (minimal), blood vessels (lowest).
- Neurons cannot regenerate; CNS injuries often lead to astrocyte proliferation for healing.
- Space-occupying lesions in the CNS create clinical signs via compression or displacement.
- The CNS shows low resistance to infection and injury.
Neuronal Responses to Injury
- Neurons are prone to necrosis due to energy demands; common results include chromatolysis, acidophilic necrosis, and unique inclusions based on disease.
- Neuronal death can follow an apoptotic or necrotic pathway based on injury type and receptor activation.
Axonal Changes and Wallerian Degeneration
- Loss of axonal integrity leads to degeneration and secondary myelin loss known as Wallerian degeneration.
- Phagocytosis of damaged cells by Schwann cells and macrophages shows clear regenerative pathways in PNS but limited in CNS.
Common Responses of CNS Cells to Injury
- Astrocytes undergo hypertrophy and hyperplasia; responses include gemistocytic and Alzheimer Type II appearances.
- Oligodendrocytes swell or hyperplasia; demyelination may occur due to factors such as infections or nutritional deficiencies.
- Microglia exhibit alterations through hypertrophy and phagocytosis of cellular debris.
Traumatic Injuries
- Traumatic CNS lesions often feature hemorrhages and tissue necrosis, which can lead to further complications like infection from fractures.
- Common traumatic injuries include concussion (transient loss of consciousness), contusions (hemorrhage with retained tissue architecture), and skull fractures.
Other Vascular Disorders
- Ischemia is a critical factor in many CNS diseases; outcomes depend on vessel damage extent and duration of ischemia.
- Systemic vasculitis, bacterial thrombi, and embolic events can lead to severe CNS complications, including ischemic and hemorrhagic lesions.### Intervertebral Disk Disease (IVDD)
- Degenerative changes in intervertebral discs occur in non-chondrodystrophic breeds due to aging or in chondrodystrophic breeds at an early age.
- Herniations happen mainly without trauma history, often between T10 and L3 or in the cervical area.
- Annulus fibrosus degeneration may lead to ruptures (Hansen type I herniation) resulting in extruded degenerated material.
- Protrusions of the annulus fibrosus into the spinal canal are identified as Hansen type II herniation.
Cervical Vertebral Stenotic Myelopathy/Wobbler Syndrome (CVSM)
- CVSM is characterized by ataxia and weakness caused by narrowed cervical vertebral canal and spinal cord compression.
- In horses, it manifests as cervical static stenosis (ages 1-4) and cervical vertebral instability (ages 8-18 months).
- Static stenosis occurs due to canal narrowing at C5-C7, while dynamic stenosis involves canal narrowing during neck flexion at C3-C5.
Nerve Injuries
- Neuropraxia results in temporary nerve paralysis due to pressure or blood flow obstruction, without structural damage.
- Axonotmesis involves disrupted axons but intact neural tubes, with potential for recovery.
- Neurotmesis refers to complete or partial nerve transection, likely resulting in permanent injury.
Central Nervous System Malformations
- CNS malformations are common in domestic animals, with potential inherited or teratogenic causes.
- Teratogens affect primarily during early pregnancy morphogenesis; viral infections can have broader timing impacts.
Hydrocephalus
- Characterized by abnormal cerebrospinal fluid accumulation leading to ventricular enlargement.
- Internal hydrocephalus pertains to ventricular fluid; external involves fluid in the arachnoid space, while communicating hydrocephalus shows bilateral dilation without detectable lesions.
- Acquired hydrocephalus is frequently obstructive, sometimes caused by in utero infections leading to duct stenosis.
Cerebellar Hypoplasia
- Common congenital defect associated with parvoviruses and pestiviruses infection during cerebellum development.
- Maternal viral infections transplacentally infect neuroblast cell precursors, leading to hypoplasia and dysplasia of the granular cell layer.
Viral Infections Causing CNS Developmental Defects
- Bovine viral diarrhoea virus leads to various disorders, including hypomyelinogenesis and skeletal defects.
- Border disease virus causes tremors and 'hairy-shaker' lambs by infecting oligodendroglia and astroglia.
- Classical swine fever virus can cause cerebellum hypoplasia.
- Feline panleukopenia virus adversely affects kittens' cerebellum during rapid development stages.
Inflammatory Lesions Terminology
- Encephalitis: Brain inflammation.
- Myelitis: Spinal cord inflammation.
- Encephalomyelitis: Combined brain and spinal cord inflammation.
- Ependymitis: Inflammation of ependymal cells.
- Choroiditis: Inflammation of choroid plexus.
- Meningitis: Meningeal inflammation; subdivided into leptomeningitis (pia-arachnoid) and pachymeningitis (dura).
Infectious Diseases of the Nervous System
- Pyogenic bacteria can cause localized abscesses from various infection routes, with key bacteria including Streptococcus, Staphylococcus, and Brucella.
- Neonatal bacterial suppurative meningitis can arise from several bacteria, presenting with cloudiness in meninges.
- Septic embolism as a complication of endocarditis can lead to CNS infections.
Important Bacterial Diseases of the CNS
- Listeriosis in ruminants can cause encephalitis, often due to poor silage with Listeria monocytogenes.
- Infectious thrombotic meningoencephalitis caused by Histophilus somni results in vasculitis and potential neurological signs, including ataxia and circling.
Viral Infections of the CNS
- Viruses like FIPV can cause severe CNS lesions through inflammatory reactions.
- Herpesviruses, specifically alphaherpesviruses, lead to necrosis and inflammation within the CNS.
- Canine herpesvirus 1 results in fatal disease in young puppies.
- Equine herpes virus 1 and 4 cause clinical signs of ataxia and paralysis, with CNS involvement through endothelial cell infection.
Prion Diseases
- Transmissible spongiform encephalopathies (TSE) are characterized by spongiform encephalopathy due to PrPSc accumulation.
- TSEs include scrapie, Bovine spongiform encephalopathy (BSE), and Chronic wasting disease, with varying clinical signs and patterns of neuronal vacuolation.
Mycotic and Algal Diseases
- Mainly opportunistic infections in immunocompromised hosts; Cryptococcus neoformans specifically targets the CNS, causing granulomatous infections.
- Inflammatory responses typically involve neutrophils and macrophages resulting in severe clinical manifestations.### Gatti and Nervous System Infections
- Common in cats, dogs, and horses; organisms enter through the cribriform plate due to nasal/sinus infections or pulmonary leukocytic trafficking.
- Gross examination shows multiple small cysts in the brain, with yeast appearing spherical (2-20 μm) and surrounded by a non-staining capsule.
Idiopathic Inflammatory Diseases
- Neuritis of the cauda equina (Polyneuritis equi):
- Clinical signs include tail paralysis, urinary incontinence, faecal retention, weakness, and muscle atrophy.
- Etiology is unknown, potentially autoimmune; may follow viral infection.
- Affects sacral and coccygeal nerves; grossly, affected roots are thickened and discolored due to chronic hemorrhage, with granulomatous inflammation and fibrosis microscopically.
Degenerative Diseases of the Nervous System
-
Malacia and Malacic Diseases:
- Malacia indicates softening due to necrosis; encephalomalacia is brain necrosis, myelomalacia is cord necrosis.
- Softening of grey matter termed poliomalacia, and white matter leukomalacia, with pathology tied to specific syndromes.
-
Polioencephalomalacia (PEM):
- Affecting ruminants, characterized by edema and laminar necrosis; largely caused by thiamine deficiency due to diet changes.
- Clinical signs include blindness and convulsions; lesions fluoresce under UV light.
- Histology shows laminar necrosis with shrunken neurons.
-
Salt Poisoning/Water Deprivation:
- Occurs in swine, sheep, cattle post excessive sodium chloride consumption; complications arise from dehydration.
- Pathogenesis involves Na+ movements causing cerebral edema due to osmotic gradients.
- Lesions include cerebral edema and laminar cortical neuronal loss.
-
Lead Poisoning:
- Common in farm animals; acute symptoms include muscle tremors and recumbency; subacute cases can exhibit laminar cortical necrosis.
-
Focal Symmetrical Encephalomalacia (FSE):
- Seen in lambs and calves fed high-starch diets; epsilon toxin from C. perfringens type D induces brain necrosis.
- Characterized by bilateral malacia and hemorrhage in brain regions.
-
Mycotoxic Leukoencephalomalacia:
- Results from chronic exposure to mouldy corn in horses; caused by fumonisin B1.
- Clinical signs include impaired vision and staggering; white matter necrosis occurs.
Other Degenerative Diseases
-
Hepatic Encephalopathy (HE):
- Metabolic disorder resulting from diminished liver function; leads to impaired detoxification.
- Histopathological findings include microcavitation of myelin and Alzheimer-type II astrocytes.
-
Copper Deficiency:
- Causes swayback in lambs via congenital deficiency and enzootic ataxia post-birth.
- Histology shows axonal degeneration and demyelination.
-
Perennial Ryegrass Staggers:
- Affects ruminants in regions like Australia and Europe; due to neurotoxic lolitrems.
- Symptoms include tremors and ataxic gait; often resolves within weeks after removing from pasture.
-
Equine Laryngeal Hemiplegia:
- Causes airway obstruction leading to “roaring” during exertion; linked to idiopathic degeneration of the recurrent laryngeal nerve.
Neoplastic Diseases of the Nervous System
- Neoplasms categorized as either CNS or PNS; primary originate within the system while secondary originate elsewhere.
- Astrocytomas: Common intracranial tumors, especially in brachycephalic breeds; malignancy dictates structural changes.
- Oligodendrogliomas: Typically found in brachycephalic breeds, characterized by a well-demarcated gray appearance.
- Meningiomas: Common in dogs and cats, generally benign; associated with low metastasis risk.
- Hematopeitic Tumors: Can metastasize to CNS; examples include lymphosarcoma and malignant melanoma.
Cholesterol Granulomas
- Aging-related change in choroid plexus, particularly in older horses due to repeated hemorrhage; large granulomas can lead to obstructive hydrocephalus.
Cerebrospinal Fluid (CSF) Analysis
- CSF serves crucial functions in CNS health, primarily formed by the choroid plexus.
- Normal CSF is clear, colorless, low in protein, and acellular, with species-specific variations in total nucleated cell count.
- CSF collection indicated for neurologic diseases but contraindicated in cases of cranial trauma.
- Analysis assesses colour, turbidity, protein concentration, and total cell count to differentiate disease processes.
- Macroscopic evaluation can reveal blood presence, whereas turbidity indicates increased cells/proteins.
- Increased protein may suggest various CNS disorders; cellular stability can be enhanced post-collection with fresh plasma addition.
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Description
This quiz covers the essential procedures in performing a postmortem examination on the central nervous system (CNS) of animals, particularly those with neurological diseases. It emphasizes the importance of examining the CNS in cases of paresis or paralysis and provides guidance on localized examination based on clinical findings.
