Lymphoid system

Question 1

what causes splenic congestion

Answer 1

barbiturates euthanasia
anthrax
torsion/gdv
circulatory failure
IMHA - vessels blocked with dead RBCs

Question 2

Splenic nodules

Answer 2

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

Question 3

thymus response to injury

Answer 3

lymphoid atrophy/depletion
inflammation
haemorrhage/haematomas
neoplasia
cysts
hypoplasia
atrophy
depletion

Question 4

what is SCID

Answer 4

severe combined immunodeficiency
failed production of lymphocytes - splenic/thymic hypoplasia
dogs/horses and mice affected

Question 5

mechanisms that cause SCID

Answer 5

autosomal recessive defect causing inhibition of DNA-dependent protein kinase
X-linked defect in type 1 cytokine receptors

Question 6

what effect do splenic surface indentations have

Answer 6

none - born with them

Question 7

what cells/tissues are lymphoid

Answer 7

Cells - lymphocytes
Tissues - lymph nodes, thymus, spleen, peyer’s patches

Question 8

what cells/tissue are myeloid

Answer 8

cells - granulocytes, monocytes, macrophages, erythrocytes, thrombocytes
tissue - bone marrow

Question 9

when may a stress leukogram not occur in a sick patient

Answer 9

hypoadrenocorticism (Addisonian crisis)

Question 10

non-neoplastic lymphadenopathy

Answer 10

pathophysiology - reactive hyperplasia LN enlarges, usually localised . Lymphadenitis - infection/inflammation of the lymph node

Question 11

chylothorax/abdomen cause

Answer 11

lipids transported via lymphatics, effusions may result for rupture of duct/major vessel
both are rare
treatment involves surgical repair

Question 12

Lymphangiectasia - lacteal dilation

Answer 12

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

Question 13

examples of non-neoplastic myeloid disease

Answer 13

aplastic anaemia - failure of myeloid cell production
red cell aplasia

Question 14

myeloid neoplasia

Answer 14

myeloid leukaemia - acute with immature cells or chronic with differentiated cells

Question 15

classic presentation for histiocytoma

Answer 15

young dogs <2 years
classically benign and regress over several weeks

Question 16

mast cell tumours

Answer 16

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

Question 17

approach to mast cell tumours

Answer 17

staging (or not)
surgery
chemotherapy
if non-resectable Tyrosine kinase inhibitors, mastinib, tigilanol tiglate

Question 18

feline MCT

Answer 18

cutaneous can act benign
visceral have poorer prognoses
association between mitotic rate and survival

Question 19

transmissible venereal tumoour

Answer 19

infectious
imported on dogs
can respond to chemotherapy

Question 20

lymphoid neoplasia

Answer 20

lymphoid leukaemia - t/b/natural killer cell and acute/chronic
lymphoma - b/t cell. B = better prognosis

Question 21

what is the difference betweeen immunocompromised, immunosuppressed and immunodeficient

Answer 21

immunocompromised - any aspect of host defences is deficient
immunosuppressed - immune defences are specifically impaired
immunodeficient - body’s immune system is compromised or absent

Question 22

what does lytic mean

Answer 22

goes into cells and destroys them

Question 23

what does oncogenic mean

Answer 23

transforms into tumourous cells

Question 24

how does a virus enter a cell

Answer 24

utilises natural receptors on the cell surface and are endocytosed
can enter through direct injection or with fusion of the envelope

Question 25

canine distemper virus

Answer 25

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.

Question 26

canine parvovirus/feline panleukopenia

Answer 26

non-enveloped DNA
causes V+/D+
e.coli continues GI infection
destroys WBC precursors in bone marrow and damages mucosal barrier

Question 27

FeLV

Answer 27

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

Question 28

FIV

Answer 28

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

Question 29

positive predictive value

Answer 29

likelihood of having disease when testing positive

Question 30

what are howell-jolly bodies

Answer 30

nuclear remnants not removed properly as the RBC left the bone marrow

Question 31

what is anisocytosis

Answer 31

RBCs of different sizes due to differing ages

Question 32

what is evans syndrome

Answer 32

combined IMHA and IMTP

Question 33

what drug can be used as an anti-thrombotic?

Answer 33

aspirin

Question 34

differentials for neutropaenia

Answer 34

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

Question 35

when is a pyrexia a PUO

Answer 35

pyrexia lasting upwards of 72h