Multifocal and Diffuse Brain Disorders

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Questions and Answers

Which of the following is NOT considered a multifocal and diffuse brain disorder?

  • Vitamin deficiency (correct)
  • Infectious and inflammatory conditions
  • Traumatic brain injury
  • Degenerative conditions

Which diagnostic method is NOT typically used in the initial approach to meningoencephalitis?

  • Biopsy (correct)
  • Multifocal clinical signs and localization
  • Signalment and history
  • MRI and CSF analysis

Which of these viruses belongs to the Rhabdoviridae family?

  • Lyssa virus (correct)
  • Feline infectious peritonitis virus
  • West Nile virus
  • Distemper virus

Which animal is LEAST likely to be susceptible to rabies?

<p>Opossum (D)</p> Signup and view all the answers

In the context of rabies, what does 'neurotrophic' mean?

<p>The virus has a preference for nerve tissue. (A)</p> Signup and view all the answers

What is the typical incubation period for rabies in dogs?

<p>3-8 weeks (A)</p> Signup and view all the answers

Which of the following is a characteristic of the prodromal phase of rabies?

<p>Dilated pupils (D)</p> Signup and view all the answers

Which of the following is a typical clinical sign of the furious form of rabies?

<p>Photophobia (B)</p> Signup and view all the answers

Which diagnostic test is considered the gold standard for confirming rabies infection postmortem?

<p>Direct Fluorescent Antibody (DFA) test (B)</p> Signup and view all the answers

What are Negri bodies?

<p>Viral inclusion bodies found in nerve cells (A)</p> Signup and view all the answers

Which of the following is true regarding rabies vaccination in dogs?

<p>It involves an initial immunization followed by boosters. (C)</p> Signup and view all the answers

What type of virus is the canine distemper virus?

<p>Paramyxovirus (A)</p> Signup and view all the answers

Which of the following is considered an 'extra-neural' sign of distemper in dogs?

<p>Hyperkeratosis (D)</p> Signup and view all the answers

What is myoclonus, often seen in dogs with the CNS form of distemper?

<p>Involuntary, repetitive muscle contractions (B)</p> Signup and view all the answers

In cases of canine distemper, which diagnostic test is performed on epithelial cell swabs?

<p>Immunofluorescence (IF) (C)</p> Signup and view all the answers

Which statement is most accurate regarding neurologic therapy for dogs with distemper?

<p>Seizures are managed with prophylactic therapy. (C)</p> Signup and view all the answers

What is the recommended vaccination schedule for canine distemper?

<p>Every 3-4 weeks between 6-16 weeks of age, then every 3 years (A)</p> Signup and view all the answers

What percentage of cats with the nervous form of FIP (Feline Infectious Peritonitis) show CNS involvement?

<p>30% (D)</p> Signup and view all the answers

Which form of FIP (Feline Infectious Peritonitis) is characterized by a partial cellular response?

<p>Dry form (A)</p> Signup and view all the answers

What diagnostic tool is considered most reliable for diagnosing the CNS form of FIP?

<p>Tissue diagnosis with immunohistochemistry (A)</p> Signup and view all the answers

Which medication has shown promise in clinical trials for treating FIP, particularly in cases with CNS involvement?

<p>GS-441524 (Obeldesivir) (B)</p> Signup and view all the answers

Which of the following is NOT a type of non-infectious meningoencephalitis of unknown origin (MUO)?

<p>Steroid responsive meningitis-arteritis (SRMA) (A)</p> Signup and view all the answers

Which breed was necrotizing meningoencephalitis (NME) initially described in?

<p>Pugs (C)</p> Signup and view all the answers

What is a key characteristic of the lesions associated with Necrotizing Leukoencephalitis (NLE)?

<p>Large, focal, asymmetric necrosis with cyst formation (C)</p> Signup and view all the answers

Which type of meningoencephalitis is characterized by granulomas often found in the brain stem?

<p>Granulomatous Meningoencephalitis (GME) (C)</p> Signup and view all the answers

Which of the following is a typical signalment characteristic for dogs affected by Necrotizing Encephalitis (NE)?

<p>Young dogs, around 4.5 years old on average (A)</p> Signup and view all the answers

What is the primary characteristic of the lesions in dogs affected by Steroid Responsive Meningitis Arteritis (SRMA)?

<p>Severe meningitis and damage to small arteries of the meninges (B)</p> Signup and view all the answers

Which of the following breeds has a known predisposition for Steroid Responsive Meningitis Arteritis (SRMA)?

<p>Beagle (C)</p> Signup and view all the answers

Which of the following is NOT a typical clinical sign associated with Steroid Responsive Meningitis Arteritis (SRMA)?

<p>Seizures (A)</p> Signup and view all the answers

What is a common initial treatment for most immune-mediated CNS disorders?

<p>Prednisone (B)</p> Signup and view all the answers

Besides prednisone, which of the following is used in the treatment protocols for immune-mediated CNS disorders?

<p>Lomustine (CCNU) (A)</p> Signup and view all the answers

What percentage of disorders causing multifocal brain disorder presentations in small animals are immune mediated?

<p>80% (D)</p> Signup and view all the answers

Which of the following is true regarding multifocal brain disorders?

<p>Multifocal brain disorders are a common presentation in small animal neurology (B)</p> Signup and view all the answers

A dog presents with fever, lethargy, and cervical pain. CSF analysis reveals elevated protein and white blood cells. Which of the following is the MOST likely differential diagnosis, based solely on this information?

<p>Steroid-responsive Meningitis Arteritis (SRMA) (D)</p> Signup and view all the answers

A veterinary neurologist is presented with multiple canine patients exhibiting neurological symptoms. Based on the information provided, which statement is MOST accurate?

<p>Obtaining brain tissue via biopsy and performing histopathology are recommended to confirm a diagnosis of NME. (B)</p> Signup and view all the answers

An unvaccinated stray dog is brought in displaying acute behavioral changes, including aggression and disorientation. Which of the following is the MOST appropriate next step?

<p>Quarantine the animal and observe for ten days. (B)</p> Signup and view all the answers

Lily arrives exhibiting lethargy, fever and pain. After some time, Lily begins presenting with a hunched back, and ultimately is transferred to neurology for assistance. Which of the following neurological conditions is the LEAST likely to contribute to these symptoms?

<p>NME (D)</p> Signup and view all the answers

What is the typical course of CNS signs associated with canine distemper?

<p>Relatively rapid progression due to the diffuse nature of the disease (D)</p> Signup and view all the answers

What is the primary mechanism by which rabies virus spreads within the host?

<p>Through retrograde axonal transport within peripheral nerves (C)</p> Signup and view all the answers

Why is serological testing not considered a reliable diagnostic tool for rabies in vaccinated animals?

<p>Antibodies produced post-vaccination cannot be differentiated from those produced during natural infection. (C)</p> Signup and view all the answers

What is the most common initial treatment for most immune-mediated CNS disorders, as indicated in the material?

<p>Glucocorticoids (e.g., Prednisone) (C)</p> Signup and view all the answers

Which of the following components is unique to modified live rabies vaccines, such as PureVax Feline Rabies?

<p>Canarypox virus expressing rabies glycoprotein (A)</p> Signup and view all the answers

When considering a diagnosis of Granulomatous Meningoencephalitis (GME), which of the following factors is LEAST likely to influence the prognosis?

<p>The dog's blood type (C)</p> Signup and view all the answers

In the context of multifocal brain disorders, which category is LEAST likely to be a direct cause but can exacerbate underlying conditions?

<p>Nutritional deficiency (D)</p> Signup and view all the answers

Which of the following statements best describes the role of viral load in the manifestation of neurological signs in canine distemper?

<p>The development and severity of neurological signs depend on the complex interaction between viral load, host immune response, and viral strain pathogenicity. (C)</p> Signup and view all the answers

What is the reported success rate of GS-441524 (Obeldesivir) in treating cats with the nervous form of FIP?

<p>75% (A)</p> Signup and view all the answers

Besides supportive care, which of the following medications is typically administered to address myoclonus in dogs with distemper?

<p>Procainamide or lidocaine (D)</p> Signup and view all the answers

What is the MOST crucial aspect of a patient's history to consider when evaluating a potential case of meningoencephalitis?

<p>Travel and vaccination history. (A)</p> Signup and view all the answers

In a patient suspected of having a multifocal brain disorder, what is the MOST important initial diagnostic consideration?

<p>Ruling out infectious or inflammatory conditions. (A)</p> Signup and view all the answers

What is the primary reason dogs and cats are included in the wildlife rabies reservoir in certain countries?

<p>They exist as feral populations in those regions. (D)</p> Signup and view all the answers

What is the MOST significant factor influencing the incubation period of the rabies virus?

<p>The distance the virus must travel to reach the brain. (A)</p> Signup and view all the answers

What is the mechanism by which the rabies virus gains entry into the nervous system?

<p>Retrograde axonal transport. (D)</p> Signup and view all the answers

Why might an animal with rabies exhibit increased salivation?

<p>Due to the virus affecting nerves innervating the salivary glands. (C)</p> Signup and view all the answers

What is the primary reason cats are statistically the most common domestic animal diagnosed with rabies on the East Coast?

<p>Cats are more likely to be unvaccinated and allowed outdoors compared to dogs. (B)</p> Signup and view all the answers

What is the MOST common neurological sign seen in young dogs affected by the gray matter form of canine distemper?

<p>Seizures. (A)</p> Signup and view all the answers

A dog presents with twitching which is characterized by abrupt, shock-like movements. What specific term describes these clinical signs?

<p>Myoclonus. (D)</p> Signup and view all the answers

Why is it crucial to handle samples for canine distemper PCR testing with extreme care?

<p>To avoid false positive results due to human measles virus. (B)</p> Signup and view all the answers

What is the known efficacy of specific antiviral medications in treating the CNS form of Feline Infectious Peritonitis (FIP)?

<p>Medication improves the conditions, however relapses are common. (C)</p> Signup and view all the answers

What distinguishes necrotizing meningoencephalitis (NME) from granulomatous meningoencephalitis (GME) in terms of lesion distribution?

<p>NME primarily affects the cortex, while GME affects white matter and the brainstem (D)</p> Signup and view all the answers

What cellular change is MOST commonly observed in the cerebrospinal fluid (CSF) of dogs with steroid-responsive meningitis-arteritis (SRMA)?

<p>Neutrophilic pleocytosis. (C)</p> Signup and view all the answers

What is the typical age range for dogs affected by steroid-responsive meningitis-arteritis (SRMA)?

<p>5 to 19 months. (B)</p> Signup and view all the answers

Why is additional immunosuppressive therapy typically added to the treatment plan for dogs with GME, NME, or SRMA?

<p>To prevent the recurrence of clinical signs and reduce the need for long-term steroid use. (B)</p> Signup and view all the answers

Considering the approach to multifocal brain disorders, which factor would LEAST influence the decision to initiate immediate empiric antimicrobial therapy?

<p>A complete vaccination history and lack of systemic signs. (C)</p> Signup and view all the answers

When evaluating a dog presenting with potential neurological signs of rabies, what historical detail would MOST increase suspicion for rabies, warranting extreme caution?

<p>The dog was recently adopted from a shelter with unknown vaccination history in an area known for raccoon rabies. (B)</p> Signup and view all the answers

What is the MOST critical factor that determines the distribution and severity of central nervous system (CNS) lesions in canine distemper cases?

<p>The dog's age and the specific strain of the distemper virus. (B)</p> Signup and view all the answers

A cat presents with neurological signs suggestive of Feline Infectious Peritonitis (FIP), but the blood work is largely unremarkable. What action should the veterinarian perform?

<p>Consider FIP as a possible diagnosis, as CNS involvement can occur with minimal systemic signs. (D)</p> Signup and view all the answers

What is the MOST important consideration when choosing between different immunosuppressive drugs for long-term management of non-infectious meningoencephalitis?

<p>The potential for bone marrow suppression and cumulative side effects. (C)</p> Signup and view all the answers

Which diagnostic finding is MOST consistent with steroid-responsive meningitis-arteritis (SRMA) in dogs?

<p>Markedly elevated CSF protein and neutrophilic pleocytosis. (B)</p> Signup and view all the answers

A dog presents with a one-week history of progressive neurological signs, including seizures and behavioral changes. Which of the following differentials would be the LEAST likely, assuming the dog is fully vaccinated and lives in a suburban environment?

<p>Canine Distemper. (D)</p> Signup and view all the answers

When diagnosing Feline Infectious Peritonitis (FIP), which sign(s) is MOST specific to nervous system involvement?

<p>Seizures, ataxia, and behavioral changes. (B)</p> Signup and view all the answers

Which of the following findings would be MOST suggestive of a diagnosis of rabies in a dog presenting with acute neurological signs?

<p>Rapidly progressive behavioral changes and unexplained aggression in an unvaccinated dog. (A)</p> Signup and view all the answers

A 6-month-old Yorkshire Terrier presents with seizures, progressive ataxia, and vision deficits. What is the MOST likely differential diagnosis given the breed and age?

<p>Necrotizing Encephalitis (NE). (D)</p> Signup and view all the answers

When considering the prognosis for dogs diagnosed with non-infectious meningoencephalitis, which statement is MOST accurate?

<p>Dogs with SRMA typically have a better prognosis compared to those with NME or GME, given appropriate treatment. (D)</p> Signup and view all the answers

You are presented with a confusing neurological case. Which step would be LEAST helpful in narrowing down a diagnosis of multifocal brain disease?

<p>A single CBC and serum chemistry panel, without further diagnostics. (A)</p> Signup and view all the answers

Which statement is MOST accurate regarding the typical treatment approach for dogs diagnosed with granulomatous meningoencephalitis (GME)?

<p>Steroids is the foundation but additional immunosuppressants are required. (C)</p> Signup and view all the answers

What diagnostic technique is considered the gold standard for confirming a clinical diagnosis of Feline Infectious Peritonitis (FIP) affecting the central nervous system ante-mortem (before death)?

<p>Histopathology of brain tissue with positive coronavirus immunostaining. (C)</p> Signup and view all the answers

Considering the zoonotic importance of rabies, what is the MOST appropriate course of action immediately following a confirmed diagnosis of rabies in a dog?

<p>Notify public health authorities to initiate contact tracing and post-exposure prophylaxis. (A)</p> Signup and view all the answers

A veterinary neurologist diagnoses a patient with a multifocal brain disorder. The client asks if it could be genetic. How should the veterinarian respond?

<p>&quot;Genetic is involved in some inflammatory conditions&quot;. (D)</p> Signup and view all the answers

What is the BEST initial treatment of a patient with steroid-responsive meningitis-arteritis (SRMA)?

<p>Steroids. (A)</p> Signup and view all the answers

Which of these is NOT a common condition seen with multifocal disorders?

<p>Dental. (D)</p> Signup and view all the answers

Which is the WORST option for a prognosis?

<p>Degenerative. (C)</p> Signup and view all the answers

If a DVM is presented with an animal that they suspect has Rabies, which should they NOT do due to extremely high risk?

<p>Tap the patient's spinal fluid immediately. (B)</p> Signup and view all the answers

A dog has potential steroid-responsive meningitis arthritis (SRMA). Which is the LEAST beneficial lab test?

<p>X-ray. (A)</p> Signup and view all the answers

Which condition may be LESS treatable long-term?

<p>GME. (C)</p> Signup and view all the answers

What is one of the MAIN organs involved in post-mortem rabies discovery?

<p>Brain. (D)</p> Signup and view all the answers

What is a possible side effect of Procarbazine?

<p>Bone marrow suppression. (D)</p> Signup and view all the answers

A veterinarian is treating a cat with FIP, but the owners mentioned that they did not want any type of experimental medicine. What should the DVM do?

<p>Administer steroids only. (C)</p> Signup and view all the answers

Which factor is LEAST important when initially evaluating a dog from Louisiana post-hurricane for potential meningoencephalitis?

<p>Availability of advanced imaging (D)</p> Signup and view all the answers

What is the MOST critical action to minimize false positives when performing PCR testing for canine distemper?

<p>Ensuring sterile sample handling (B)</p> Signup and view all the answers

Which of these is NOT one of the main categories of disorders that can cause multifocal and diffuse brain disease?

<p>Neoplastic conditions (D)</p> Signup and view all the answers

What does 'multifocal' mean in the context of neurological disorders?

<p>There are several distinct areas of the brain involved (C)</p> Signup and view all the answers

In a case of suspected rabies, what is the significance of the virus being 'neurotropic'?

<p>The virus mainly replicates in the nervous system (B)</p> Signup and view all the answers

How does the rabies virus typically enter the nervous system?

<p>Via retrograde axonal transport in peripheral nerves (A)</p> Signup and view all the answers

Why is travel history particularly important when assessing a patient for potential infectious meningoencephalitis?

<p>Infectious disease prevalence varies geographically (A)</p> Signup and view all the answers

What is a key difference between necrotizing meningoencephalitis (NME) and granulomatous meningoencephalitis (GME) in lesion distribution?

<p>NME primarily affects the cortex while GME is more common in the white matter and brainstem (C)</p> Signup and view all the answers

Which of the following MOST accurately describes the role of a veterinarian when rabies is suspected?

<p>Prioritizing personal safety and contacting the appropriate authorities (B)</p> Signup and view all the answers

What neurological sign is MOST characteristic of the gray matter form of canine distemper in young dogs?

<p>Seizures (B)</p> Signup and view all the answers

For which condition is periventricular contrast enhancement around the fourth and third ventricles on MRI MOST suggestive?

<p>Feline Infectious Peritonitis (FIP) (D)</p> Signup and view all the answers

What is the MAIN goal of adding immunosuppressive medications (like cyclosporine or azathioprine) to the treatment plan for dogs with GME, NME, or SRMA?

<p>To calm the immune system and allow for better long-term control with less steroid use (A)</p> Signup and view all the answers

What is the initial step a veterinarian should take when they suspect a dog may have rabies?

<p>Isolate the animal and consult with health authorities (C)</p> Signup and view all the answers

In a dog presenting with multifocal brain signs, which diagnostic result would MOST strongly suggest SRMA (steroid-responsive meningitis-arteritis)?

<p>Neutrophilic pleocytosis in CSF (D)</p> Signup and view all the answers

What is the MOST common way Feline Infectious Peritonitis (FIP) manifests in cats?

<p>Through a spontaneous mutation of a coronavirus (C)</p> Signup and view all the answers

What is the MOST likely cause of a positive PCR test for distemper in a dog, if the test was not correctly performed by the lab technician?

<p>There was contamination from the technician who had a measles infection (C)</p> Signup and view all the answers

In the context of rabies transmission, what role do domestic animals like dogs and cats play in certain countries such as India?

<p>They can act as wildlife reservoirs, maintaining and spreading the virus (A)</p> Signup and view all the answers

What is a common prodromal sign of rabies?

<p>Flicking at the inoculation site (A)</p> Signup and view all the answers

What is the typical signalment of a dog that's most likely to have steroid-responsive meningitis arteritis (SRMA)?

<p>A young dog with fever and neck pain (C)</p> Signup and view all the answers

Why might the rabies incubation period be shorter if the animal is bitten on the face, as opposed to the leg?

<p>The distance to the brain is shorter (B)</p> Signup and view all the answers

Which of the following best describes 'myoclonus' as it relates to canine distemper?

<p>Abrupt, shock-like muscle movements (A)</p> Signup and view all the answers

Which of the following would be the MOST appropriate initial treatment choice for a dog diagnosed with steroid-responsive meningitis-arteritis (SRMA)?

<p>High doses of corticosteroids (B)</p> Signup and view all the answers

What is the MOST important historical detail to consider when evaluating a dog with new onset aggressive behavior?

<p>Vaccination status, especially for rabies (B)</p> Signup and view all the answers

How has the approach to treating Feline Infectious Peritonitis (FIP) changed in recent years?

<p>Use of antiviral medications like GS-441524 (C)</p> Signup and view all the answers

When collecting CSF for analysis while investigating a possible case of meningoencephalitis, what is considered a positive result that confirms that there is a meningoencephalitis?

<p>Pleocytosis (C)</p> Signup and view all the answers

Why might a veterinarian consider empiric antimicrobial therapy in a patient presenting with a multifocal brain disorder?

<p>If infectious causes cannot be ruled out quickly (D)</p> Signup and view all the answers

When might West Nile Virus and Triple E be differentials in the Northeast region of the United States?

<p>During the warmer summer months (D)</p> Signup and view all the answers

What does a dog in the wildlife reservoir look like?

<p>The dog is wild (C)</p> Signup and view all the answers

What does post-mortem examination for rabies typically involve?

<p>Brain tissue examination (C)</p> Signup and view all the answers

How has the geographic distribution of certain infectious diseases changed, and why?

<p>Certain infections are becoming more prevalent in new regions due to warming climate (B)</p> Signup and view all the answers

What is a classic sign that has high suspicion of the animal having a FIP infection?

<p>Vestibular signs (A)</p> Signup and view all the answers

What is the most important thing to be concerned with if a dog is on Procarbazine long-term?

<p>Bone marrow suppression (A)</p> Signup and view all the answers

What can the clinic recommend to owners for cats diagnosed with FIP?

<p>The FIP Warriors (A)</p> Signup and view all the answers

If the DVM wants to prevent Rabies, which is the MOST appropriate?

<p>Vaccinate the animal for rabies (C)</p> Signup and view all the answers

A dog presents with a hunched back and neck pain. Which of the following differentials would be the LEAST likely to contribute to these symptoms?

<p>Cerebellar hypoplasia (B)</p> Signup and view all the answers

Upon necropsy of an animal that had rabies, what area will they evaluate?

<p>The brain (D)</p> Signup and view all the answers

What is a potential treatment option of seizures associated with the FIP infection?

<p>Anticonvulsive medications (A)</p> Signup and view all the answers

What is MOST important for sample collection for PCR collection in cases of canine distemper?

<p>Sterile collection (D)</p> Signup and view all the answers

How would one describe a dog with rabies?

<p>It depends (C)</p> Signup and view all the answers

If a dog is found to have SRMA at five years of age, is it the MOST appropriate to treat?

<p>Rarely (B)</p> Signup and view all the answers

What is true of dogs with a multifocal brain disorder?

<p>The primary differential is infectious inflammatory conditions (D)</p> Signup and view all the answers

Which of the following is the MOST crucial piece of information to obtain when taking a history for a potential meningoencephalitis case?

<p>Travel history (C)</p> Signup and view all the answers

If a dog presents with neurological signs indicative of multifocal brain disease, what should be the PRIMARY rule-out?

<p>Infectious or inflammatory condition (C)</p> Signup and view all the answers

Which of the following is the MOST accurate description of how rabies is believed to spread throughout the body?

<p>Through retrograde axonal transport, utilizing nerve pathways to reach the brain (D)</p> Signup and view all the answers

Upon suspicion of a rabies case characterized by both furious and paralytic signs, what is the MOST important reason for immediate euthanasia and testing?

<p>To prevent further transmission and allow for definitive postmortem diagnosis. (C)</p> Signup and view all the answers

How does canine distemper typically manifest in older dogs, compared to younger dogs?

<p>Older dogs tend to show more white matter involvement, while younger dogs have more gray matter involvement. (D)</p> Signup and view all the answers

What is a critical consideration when collecting samples for canine distemper PCR testing to avoid false-positive results?

<p>Wearing gloves and using clean techniques to prevent contamination with measles virus. (A)</p> Signup and view all the answers

Which statement is MOST accurate regarding Feline Infectious Peritonitis (FIP) and its diagnosis?

<p>Definitive diagnosis often requires histopathological confirmation due to the variability of clinical presentation and lab results. (A)</p> Signup and view all the answers

When interpreting MRI findings in a cat suspected of having FIP, what specific feature is MOST suggestive of CNS involvement?

<p>Periventricular contrast enhancement around the fourth and third ventricles (C)</p> Signup and view all the answers

A 6-month-old Bernese Mountain Dog presents with fever, neck pain, and stiff gait. Which condition should be HIGH on your differential list?

<p>Steroid-Responsive Meningitis-Arteritis (SRMA) (C)</p> Signup and view all the answers

You are presented with a canine patient diagnosed with GME and are initiating immunosuppressive therapy. Which drug choice would be LEAST appropriate due to its propensity for cumulative, severe side effects?

<p>Lomustine (CCNU) (A)</p> Signup and view all the answers

Flashcards

Multifocal/diffuse brain disorders

Disorders likely to affect the brain at multiple functional areas.

Rabies

Viral disease affecting the central nervous system

What causes Rabies?

Lyssa virus in the family Rhabdoviridae.

Rabies spread

Intra-axonal movement towards the CNS.

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How does Rabies spread?

Via saliva; replicates in brain and salivary glands.

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Rabies incubation periods

Dogs: 3-8 weeks, Cats: 4-6 weeks.

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Prodromal phase

initial behavioral changes.

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Diagnosing Rabies

Direct Fluorescent Antibody test on brain tissue

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Rabies histopathology

Mononuclear infiltration, Negri bodies.

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Preventing Rabies

Killed virus vaccines.

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Distemper

Viral disease affecting multiple systems.

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Distemper pathogenesis

Widespread invasion of epithelial cells and CNS.

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Extra neural signs of Distemper

Fever, conjunctivitis, hyperkeratosis.

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CNS form signs

Seizures, ataxia, myoclonus.

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Treating Distemper

Glucocorticoids, anti-seizure meds.

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Distemper prevention

Canine distemper vaccines.

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FIP

Feline infectious peritonitis, a complex immune-mediated disease.

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FIP cause

Corona virus infection, immune complex disorder

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FIP forms

Effusive (wet), dry, combined.

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FIP signs

Fever, lethargy, weight loss.

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FIP diagnosis

No single reliable test

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FIP treatment

Prednisone, antivirals (GS-441524).

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MUO

Non-infectious inflammation of the brain and meninges.

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MUO examples

NME, NE, GME

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NME

Necrotizing meningoencephalitis.

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GME

Granulomatous meningoencephalitis.

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NE

Necrotizing encephalitis.

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SRMA

Steroid-responsive meningitis-arteritis.

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MUO treatments

Immunosuppressive drugs.

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Multifocal and Diffuse Brain Disorders

Several areas of the brain are involved, or continuously spreading throughout the brain.

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Causes of Multifocal/Diffuse Brain Disorders

Infectious or inflammatory conditions, degenerative conditions, polytrauma, and metabolic or toxic conditions

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Important History Questions

Age, breed, Vaccination status and travel history.

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Diagnosing Multifocal Issues

MRI to see lesion distribution, spinal fluid analysis for pleocytosis.

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Infectious Disorder Concerns

Rickettsial, protozoal, fungal, parasitic disorders, distemper, West Nile/EEE.

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If Not Infectious...

Non-infectious meningoencephalitis (NME, GME, other).

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Rabies Virus Type

A single-stranded neurotropic virus that replicates in the nervous system.

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High Rabies Susceptibility (Wildlife)

Foxes, coyotes, wolves, skunks, raccoons, bats, rabbits.

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Rabies Infection Spread

Virus enters via bite, travels nerves to brain, multiplies, spreads to salivary glands.

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Rabies Prodromal Phase Signs

Fever, agitation, dilated pupils, flicking at the bite site.

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Rabies Furious Form Symptoms

Salivation, irritation, biting, disorientation, seizures, paralysis.

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Rabies Paralytic Form Symptoms

Generalized lower motor neuron disease and paralysis.

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Rabies Survival Time

Three to eight days, quickly progressive.

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Canine Distemper Overview

Respiratory infection leading to systemic and neurological signs.

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Distemper History Clues

Recent diarrhea, ocular discharge, hyperkeratosis, retinitis, enamel defects.

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Distemper CNS Signs (Young Dogs)

Seizures, myoclonus (twitching), behavior changes, incoordination.

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Myoclonus Definition

Abrupt, shock-like muscle movements.

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Diagnosing Distemper

Swab the cells, check antibody titers, PCR (best method).

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Distemper Treatment

Supportive care, steroids, anti-seizure medication, Keppra for myoclonus.

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FIP (Feline Infectious Peritonitis)

Coronavirus mutation leading to immune-mediated disease, CNS involvement common.

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FIP Brain MRI Signature

Periventricular enhancement around ventricles on MRI.

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FIP Treatment Approach

Antiviral medication (GS-441524), steroids, anticonvulsants

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Common MUO Forms

Necrotizing Meningoencephalitis (NME), Granulomatous Meningoencephalitis (GME).

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NME Characteristics

Immune-mediated, gray matter disease, cortex affected, severe meningitis.

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GME Characteristics

Immune-mediated, white matter disease, brainstem and spinal cord often affected.

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Necrotizing Encephalitis Signs

Lesions on brainstem/cerebellum, with tissue loss.

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SRMA Characteristics

Young dogs, fever, neck pain, joint pain; neutrophilic pleocytosis in CSF.

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Treating Immune-Mediated Issues

Steroids (prednisone), other immunosuppressants (cyclosporine, azathioprine).

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Study Notes

Okay, here are the updated study notes based on the provided text.

Approaching Multifocal and Diffuse Brain Disorders

  • Multifocal disorders involve several brain areas; diffuse disorders are continuous throughout the brain.
  • The result of both presentations is approximately the same.
  • Key categories of these disorders include infectious and inflammatory, degenerative conditions, poly-trauma, and metabolic/toxic issues.
  • Infectious and inflammatory conditions are often the main cause for multifocal localization
  • When assessing, signalment and history are crucial, along with age, breed, vaccination status, and travel history.
  • Travel history is very crucial for infections that are regionally distinct (e.g., different infections in Louisiana vs. California).
  • The presence of multifocal clinical signs should raise suspicion for infection/inflammation.
  • MRI is helpful for visualizing lesion distribution throughout the brain.
  • CSF analysis is helpful to confirm inflammation (pleocytosis, increased protein levels).
  • Bacterial infections should be ruled out initially; a CSF with 90% neutrophils suggests a chance of bacterial involvement.
  • If the CSF has more mononuclear pleocytosis other investigations should be performed.
  • Titer tests screen for rickettsial, protozoal, fungal and parasitic disorders.
  • Distemper is still seen with Triple E/West Nile Fever on the uprise

Rabies

  • First reported 5000 years ago, 1768 in Boston.
  • It is caused by Lyssa virus in the family Rhabdoviridae.
  • The virus is characterized by a single-stranded RNA with a glycoprotein envelope.
  • Rabies is neurotrophic, replicating primarily in the central nervous system (CNS).
  • Animals with high susceptibility include foxes, coyotes, wolves, jackals, skunks, raccoons, bats, and rabbits.
  • Animals with moderate susceptibility include dogs, cattle, sheep, goats, horses, and cats.
  • Low susceptibility animals: birds and opossums.
  • The Enzootic reservoir for rabies includes wildlife such as foxes, coyotes, skunks, raccoons, jackals, mongooses, bats, dogs, and cats.
  • Domestic animals affected: dogs, cats, horses, and ruminants.
  • 25,000 humans died worldwide in 2015.
  • Raccoon rabies is a major concern on the East Coast of the U.S.
  • The virus spreads to the CNS through retrograde intra-axonal flow.
  • Nutrient transport occurs from the alpha motor neuron to the nerve periphery and waste is transported back to the neuron.
  • The virus hitches a "free ride" and has free entry to the nerves.
  • Viral replication occurs in the spinal cord and brain.
  • The virus spreads centrifugally through peripheral nerves, reaching the salivary glands.
  • The incubation period depends on the length of the nerve and travel time via retrograde axonoplasmatic flow.
  • The average incubation for dogs is 3-8 weeks and for cats 4-6 weeks.
  • Initial (prodromal) signs: typically last 2-3 days; can include variable fever, licking site of inoculation due to sensory dysfunction, nervousness, agitation, searching for solitude, and dilated pupils.
  • "Lily" had a recent trip on a ferry to Martha's Vineyard.
  • "Lily" showed lethargy, fever and seemed painful three days prior to admission.
  • "Lily" developed a hunched back, cried, and bit two days prior.
  • "Lily" was reluctant to eat, remained painful, and showed proprioceptive deficits, with pain medication ineffective one day before.
  • "Lily" spent 2.5 days in the ICU before being transferred to neurology.
  • Furious rabies symptoms: salivation, irritability, viciousness, photophobia, disorientation, changes in mental status, ataxia potentially leading to tetraplegia, and grand mal seizures.
  • Dumb or paralytic rabies symptoms: LMN paralysis, CN affected first, dropped jaw, swallowing dysfunction, and coma.
  • Survival time after clinical signs is 3-8 days, with a median of 4 days.
  • Diagnostic methods include direct fluorescent antibody (DFA) tests on skin biopsies and brain tissue, RT-PCR on saliva or CSF and rapid fluorescent focus inhibition test (RFFIT) of serum or CSF.
  • Serological tests are not possible after vaccination.
  • Histopathology will show Mononuclear infiltration, Perivascular cuffing of lymphocytes or polymorphonuclear cells, Lymphocytic foci. Nodules consisting of glial cells, Negri bodies = filamentous ribonucleoproteins
  • The vaccination for dogs: killed virus (Imrab 3 TF) with initial vaccination at 3 months, a booster at 1 year, and revaccination every 1-3 years.
  • The vaccination for cats is with killed virus (Imrab 3 TF) or modified live virus, with Canarypox virus expressing rabies glycoprotein (PureVax Feline Rabies) and the same schedule as for dogs. Vaccination brings exponential drop in the likelihood of contracting rabies, but is not 100%.

Distemper

  • For the viral replication cycle, it starts with inoculation of the respiratory tract and viral replication in local B cells, T cells, and macrophages.
  • This is followed by lymphatic spread to tonsils and bronchial/retropharyngeal lymph nodes and then viral replication and lymphoid organ colonization.
  • The immune response determines if there will be widespread invasion of epithelial cells and the CNS, leading to symptomatic or asymptomatic outcomes depending on the individual.
  • Extraneural: fever, conjunctivitis, pneumonia, diarrhea, hyperkeratosis, retinitis, and cachexia are indicators in addition to neurological signs.
  • History of diarrhea, ocular discharge, hyperkeratosis and retinal/teeth abnormalities are supportive of a diagnosis of distemper.
  • Forms of encephalomyelitis in young dogs: onset with myoclonus; gray > white matter disease.
  • In mature dogs: white matter disease, myoclonus is rare.
  • Chronic old dog encephalitis occurs with forebrain changes.
  • Post-vaccinal distemper encephalitis: often in young dogs, unclear pathogenesis (very rare).
  • In the CNS form, rapid progression with, seizures, abnormal behavior, ataxia, paresis, myoclonus, cerebellar or vestibular signs, and epaxial pain can be observed.
  • Rapidly progressive CORS (cerebral, ocular, respiratory signs), but slower than rabies.
  • It may take weeks as opposed to the very rapid progression of rabies.
  • In young dogs with gray matter involvement, seizures and myoclonus are often seen.
  • Myoclonus can be the only sign.
  • Diagnostic tests for distemper include IF on epithelial cell swabs, IgM/IgG antibody titers in blood or CSF, and PCR on blood, urine, CSF, or conjunctival swabs.
  • Samples should be handled carefully when performing PCR (false positives can occur due to measles virus shedding from humans).
  • A positive PCR has an 80-90% likelihood of indicating distemper infection.
  • In post-infection, IF is 3 weeks, antibody titers 8 days to 3 weeks, and PCR has a sample dependent result
  • In post-vaccination IF is unavailable, antibody titer several months and PCR has MLV weeks result
  • Treatment is primarily supportive, aiming to aid the immune system.
  • High doses of glucocorticoids followed by maintenance doses, alongside immunomodulators help therapy.
  • Seizures can be managed with prophylactic therapy at the onset of systemic signs.
  • There is irreversible myoclonus without proven therapy, but procainamide, lidocaine, and levetiracetam can be used; levothyretacem/Keppra is often the first treatment of choice for myoclonus.
  • Vaccination is key for prevention: every 3-4 weeks between 6-16 weeks of life, then every 3 years.
  • Over 50% of dogs with neurological distemper have been vaccinated, and encephalitis has been reported after vaccination.
  • Infected dogs should be isolated as they can shed the virus for 1-2 weeks after systemic infection or longer.

FIP (Feline Infectious Peritonitis)

  • It is caused by a corona virus and is characterized by immune complex disorder and vasculitis. The virus undergoes a spontaneous mutation and generates the FIP variant.
  • Effusive (wet) form with no cellular immunity or dry with partial cellular response, or a combined form are possible presentations.
  • About 30% of cats with FIP show CNS involvement. Some cases show nearly no systemic signs.
  • the brain stem is often affected:.
  • Varying signs of feline infectious peritonitis (FIP) may include fever, lethargy, loss of appetite, weight loss, effusions in the abdomen or thorax, CNS signs like central vestibular issues, and anterior uveitis.
  • There is no single reliable test for FIP diagnosis, it requires a combination of multiple tests include blood work (CBC), chemistry profile, X-rays / ultrasound, FIP titers.
  • For diagnosing CNS form, MRI, CSF analysis, immunofluorescence antibody tests, and immunohistochemistry of tissue samples are most reliable.
  • Periventricular enhancement around the fourth and third ventricles on MRI is nearly classical for FIP.
  • FIP therapy includes prednisone for disease control, antiviral medications (GS-441524) in clinical trials, and anticonvulsants.
  • GS-441524, at 10 mg/kg SID to BID subcutaneously for 3 months, showed positive responses in 75% of cats with CNS involvement; relapses after treatment completion are possible.
  • The medication interferes with viral RNA transcription, with potential liver and kidney toxicity. The cost can be around $2000 for a 3 month treatment at 10mg/kg BID.
  • Some cats relapse after stopping antiviral treatment.
  • One cat developed an accumulation of viral substance in the bladder that caused obstruction.
  • Remdesivir showed less success than GS-441524.
  • Combining prednisolone with antivirals may prolong life in some cats.

Non-Infectious Meningoencephalitis

  • Meningoencephalitis of unknown origin (MUO) and meningitis of unknown origin are both important.
  • MUO includes necrotizing meningoencephalitis (NME, including Pug dog encephalitis), necrotizing encephalitis (NE, including Yorkshire encephalitis and necrotizing leuko-encephalitis), and granulomatous meningoencephalitis (GME).
  • Meningitis of unknown origin includes steroid-responsive meningitis-arteritis (SRMA) and idiopathic pachymeningitis of greyhounds.
  • Necrotizing Meningoencephalitis (NME): cause is unknown (immune-mediated suspected).
  • First identified in 1982 in CA and MA.
  • NME occurs in intact and neutered males and females.
  • NME has acute and chronic clinical forms. Acute forms are difficult to treat due to risk of increased ICP.
  • Recent studies show antibodies against GFAP of astrocytes in CSF along with elevated GFAP CSF levels; significance not clear, but supports the possible immune mediated condition.
  • NME is largely a gray matter disease, typically affecting the cortex with severe meningitis. The brainstem is typically spared.
  • The cortex collapses and fades away in chronic cases.
  • Inflammation of the gray matter with necrosis of the white matter below.
  • Granulomatous Meningoencephalitis (GME) has an unknown cause that is most likely immune mediated.
  • GME is more likely in middle-aged dogs, small breeds and has females.
  • GME can manifest as ocular, focal (brainstem), or disseminated (spinal cord, brainstem, forebrain) forms.
  • GME is more common in the white matter of the brainstem and sometimes includes the spinal cord.
  • Necrotizing Encephalitis (NE) and Necrotizing Leukoencephalitis (NLE) are idiopathic.
  • NLE is described in Yorkshire terriers and diagnosed in other breeds like French bulldogs or Boston terriers.
  • Symptoms appear around ~4.5 years (range 1-10 yrs) with no gender predilection.
  • NLE has Large, focal, asymmetric necrosis, cyst formation, severe inflammation around necrotic, mostly white matter disease, Meninges is mostly spared, and located in the mid brain, brainstem, cerebellum.
  • Steroid Responsive Meningitis Arteritis (SRMA) is most likely immune mediated.
  • SRMA is not fully understood, it includes upregulation of CD4, CD8 & CDIIT-cells, downregulation of interleukins IL2, IL4 and interferon, high level of IL8 and IgA, severe meningitis and damage to small arteries of meninges.
  • JSRMA can appear with joint, heart and thyroids' disease.
  • Younger dogs (5-19 months old) are more susceptible, it would be very unlikely in dogs older than the age of 2.
  • Those Breeds are beagles, Bernese mountain dogs, boxers, border collies, English Springer Spaniels, Jack Russells, Labrador retrievers, Nova Scotia Duck Toll retrievers, Weimaraners, whippets, and Wirehaired Pointing Griffons.
  • SRMA clinical signs: are fever, lethargy, stiff gait, neck and thoracolumbar pain, and joint pain.
  • In some cases, there's reduced heart function and pericardial fluid.
  • Diagnostic features: signalment, clinical signs, CSF analysis (granulcytic pleocytosis), tests for C-reactive protein. Values can go up as high as 1500 Y-pod cells in the CSF (upper limit 8).
  • Due to damaged arteries, protein can be elevated in the range of 100-300 (normal range up to 25)
  • Rule out infectious disorders, a joint tap (if indicated), and MRI.
  • Prednisone, dexamethasone IV, methylprednisolone IV, and prednisone PO can be used.
  • Use it to slowly taper off and continue at the lowest possible level.
  • Immunomodulating therapy: lomustine (CCNU), procarbazine, cytosine arabinoside, cyclosporine, leflunomide, and azathioprine.
  • Steroids help to slow down the immune system, but dogs respond poorly to long-term treatment.
  • Procarbazine may be very helpful to replace steroids; Cytosine can only be administered via IV so it has to be given recurring every 4 weeks; Low-Mustine CCNU has cumulative side effects so there is also a time limit.

Summary

  • Multifocal brain disorders are common in small animal neurology.
  • Inflammatory and infectious disorders are most common.
  • Of the disorders, about 80% are immune mediated, which are often treatable.
  • Toxic and metabolic conditions are another important group.
  • Trauma and poly-trauma cases are often presented to ER.
  • Degenerative conditions are rare and challenging to diagnose.
  • Expertise in infectious and non-infectious brain disorders is crucial for small animal medicine, internships/residencies, and private practice.

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