Lymphoid system Flashcards
what causes splenic congestion
barbiturates euthanasia
anthrax
torsion/gdv
circulatory failure
IMHA - vessels blocked with dead RBCs
Splenic nodules
Haematoma
hyperplasia
abscess
lymphoid reticular hyperplasia
senile nodular hyperplasia - common incidental change in older dogs, can be caused by incomplete splenic contraction (wrinkley)
capsule/peritonitis
neoplasia
thymus response to injury
lymphoid atrophy/depletion
inflammation
haemorrhage/haematomas
neoplasia
cysts
hypoplasia
atrophy
depletion
what is SCID
severe combined immunodeficiency
failed production of lymphocytes - splenic/thymic hypoplasia
dogs/horses and mice affected
mechanisms that cause SCID
autosomal recessive defect causing inhibition of DNA-dependent protein kinase
X-linked defect in type 1 cytokine receptors
what effect do splenic surface indentations have
none - born with them
what cells/tissues are lymphoid
Cells - lymphocytes
Tissues - lymph nodes, thymus, spleen, peyer’s patches
what cells/tissue are myeloid
cells - granulocytes, monocytes, macrophages, erythrocytes, thrombocytes
tissue - bone marrow
when may a stress leukogram not occur in a sick patient
hypoadrenocorticism (Addisonian crisis)
non-neoplastic lymphadenopathy
pathophysiology - reactive hyperplasia LN enlarges, usually localised . Lymphadenitis - infection/inflammation of the lymph node
chylothorax/abdomen cause
lipids transported via lymphatics, effusions may result for rupture of duct/major vessel
both are rare
treatment involves surgical repair
Lymphangiectasia - lacteal dilation
intestinal lymphatics dilate and lose chyle into the lumen causing a protein losing enteropathy
can be congenital, obstructive in cause
management includes low fat diet
lymphopaenia present on haematology
hyperechoic lacteals on ultrasound
examples of non-neoplastic myeloid disease
aplastic anaemia - failure of myeloid cell production
red cell aplasia
myeloid neoplasia
myeloid leukaemia - acute with immature cells or chronic with differentiated cells
classic presentation for histiocytoma
young dogs <2 years
classically benign and regress over several weeks
mast cell tumours
form of granulocyte appearing as reactive lymph nodes.
Usually older dogs and common
cytology very good for diagnosis
locally invasive
histamine release can invoke anaphylaxis - anti-histamines
approach to mast cell tumours
staging (or not)
surgery
chemotherapy
if non-resectable Tyrosine kinase inhibitors, mastinib, tigilanol tiglate
feline MCT
cutaneous can act benign
visceral have poorer prognoses
association between mitotic rate and survival
transmissible venereal tumoour
infectious
imported on dogs
can respond to chemotherapy
lymphoid neoplasia
lymphoid leukaemia - t/b/natural killer cell and acute/chronic
lymphoma - b/t cell. B = better prognosis
what is the difference betweeen immunocompromised, immunosuppressed and immunodeficient
immunocompromised - any aspect of host defences is deficient
immunosuppressed - immune defences are specifically impaired
immunodeficient - body’s immune system is compromised or absent
what does lytic mean
goes into cells and destroys them
what does oncogenic mean
transforms into tumourous cells
how does a virus enter a cell
utilises natural receptors on the cell surface and are endocytosed
can enter through direct injection or with fusion of the envelope
canine distemper virus
morbillivirus related to measles, RNA enveloped has to be transcribed - can have mistakes, easily killed with disinfectants
causes lymphocyte destruction
oro-nasal infection replicating in lymphoid tissue, looks like a cold with thick crusty snot initially.
canine parvovirus/feline panleukopenia
non-enveloped DNA
causes V+/D+
e.coli continues GI infection
destroys WBC precursors in bone marrow and damages mucosal barrier
FeLV
retrovirus - RNA virus
4 subtypes - A, B, C, T
transmitted through grooming - saliva, increased risk when being groomed by mum with population density and poor hygiene
shed in saliva, respiratory secretions, urine, milk and faeces
detection in virus PCR - antigen wont show for 30 days
FIV
viral RNA/proviral DNA
kittens born to + queen can have anti-bodies to 12 weeks
infected for life but have normal lifespan, recurrent infections, gingivitis, neoplasia
Debates as to who to test
positive predictive value
likelihood of having disease when testing positive
what are howell-jolly bodies
nuclear remnants not removed properly as the RBC left the bone marrow
what is anisocytosis
RBCs of different sizes due to differing ages
what is evans syndrome
combined IMHA and IMTP
what drug can be used as an anti-thrombotic?
aspirin
differentials for neutropaenia
Increased demand - most common
- migration to tissue for inflammation
- shift from circulating to marginating pool
Increased demand
- immune mediated neutropaenia
- drugs/toxins/viruses
Decreased production
- viral disease
- drugs/toxins
- bone marrow disease
- inherited defects
Unknown mechanisms - least common
- feline idiopathic neutropaenia
- breed associated
when is a pyrexia a PUO
pyrexia lasting upwards of 72h
