Pathology: infectious and non-infectious diseases of the neural system Flashcards
Septic bacterial emboli are usually seen in young or old animals?
Young
Where in the brain do septic bacterial emboli typically become lodged?
In the cerebrum, at the grey/white matter junction
Causing thrombosis, malacia and abscessation
Histologically will see astrocytic encapsulation
A cow with a septic bacterial embolus is most commonly due to what bacteria?
T. pyogenes
Histophilus somnus
Staph aureus
A lamb with a septic bacterial embolus is most commonly due to what bacteria?
Staph aureus due to tick pyemia
A horse with a septic bacterial embolus is most commonly due to what bacteria?
Strep equi
A dog with a septic bacterial embolus is most commonly due to what bacteria?
Staph aureus
What causes Thromboembolic Mengingoencephalitis (TME) in cattle?
- Histophilus somni (a gram neg coccobacillus)
Causing acute vasculitis which primarily affects the CNS +/- lungs
What bacteria are most commonly associated with abscesses in the brain?
T. pyogenes
Strep spp
Staph spp
Pseudomonas aeruginosa
What are the 2 routes of infection to an abscess in the brain or spinal cord?
- Hematogenous spread
- Direct extension from a penetrating trauma, otogenic or frontal sinus
e. g. migrating grass seed, tail docking in pigs or bulls, or tail biting
An abscess of the pituitary fossa in cattle is usually caused by?
Hematogenous spread of bacteria either from the caudal nasal cavity or frontal sinuses
e.g. nose rings in bulls, or dehorning older cattle
note: patient usually presents with a jaw drop or exopthalmus
At what age is neonatal septicemia most common and why?
Within the first 2 weeks of life
Usually colostrum quantity or quality is lacking, or intrusion through the umbilicus
What are the most commonly found bacteria in neonatal septicemia?
(Calves, foals, small ruminants and swine)
Calves: E.coli, Salmonella, and Pasteurella spp
Foals: Salmonella spp and Actinobacillus equuli
Small ruminaints: Staph. pyogenes
Swine: Hemophilus parasuis
note: these bacteria will release endotoxins and cell wall components, leading to a cytokine secretion, adhesion of neutrophils to the endothelium and subsequent damage and vasculitis
What is the most common bacterial pathogen associated with swine meningitis?
Streptococcus suis
What are the common lesions found in Streptococcal sepsis in piglets?
Lesions are mainly seen in weaned piglets and are associated with lymphadenopathy, meningitis, arthritis, and endocarditis.
Lesions may include fibrinopurulent exudates in the brain, swollen joints, fibrinous serositis, and cardiac valvular vegetation.
Splenomegaly and petechial hemorrhages indicating septicemia are common.
What causes Listeriosis in sheep?
Listeria monocytogenes (gram positive and facultative intracellular bacterium)
recall: this is a zoonotic disease
What are the lesions associated with Listeriosis in sheep?
microabscesses in the brainstem due to retrograde movement up the trigeminal nerve
meningoencephalitis
note: can also cause abortion, septicemia and conjunctivitis
A dog with nonsuppurative meningoencephalitis in the ventral brainstem and periventricular tissue is indicative of what disease?
Ehrlichiosis
agent: Ehrlichia canis
A dog with disseminated suppurative vasculitis is indicative of what disease?
Rocky mountain spotted fever
agent: Rickettsia rickettsii
A dog/ fox with cerebellar meningitis is indicative of what disease?
Salmon poisoning
agent: Neorickettsia helminthoeca