Exam 2 - Bovine Lymphosarcoma

Question 1

what is the only form of lymphoma that is related to bovine leukemia virus?

Answer 1

enzootic bovine lymphoma

Question 2

what are the 5 forms of lymphoma that affect cows?

Answer 2

cutaneous

juvenile

thymic

hemal lymph node enlargement

enzootic bovine lymphoma

Question 3

what cows are commonly affected by cutaneous lymphoma?

Answer 3

young - under 1-3 years of age

Question 4

what clinical signs are seen with cutaneous lymphoma in cows?

Answer 4

extreme lymphadenopathy

Question 5

the prevalence of BLV is higher in _____ cattle than in _______ cattle

Answer 5

dairy higher than beef

Question 6

T/F: there is no breed or sex predilection for BLV

Answer 6

true

Question 7

why are some cattle believed to be resistant to BLV infection?

Answer 7

major histocompatibility complex - confers susceptibility or resistance to BLV infection due to differences in allele types

Question 8

T/F: infections of BLV increase with age

Answer 8

true

Question 9

how is BLV transmitted? what is the common means of transmission?

Answer 9

relies on transmission of one infected lymphocyte to another bovid through blood

iatrogenic - same instruments used for dehorning/castration, ear taggers, same needles used

rectal palpation - damage to rectal mucosa

reported cases of in utero transmission

biting flies - lower risk of transmission

Question 10

what cattle are affected by juvenile lymphoma?

Answer 10

extremely rare - seen in animals 2-3 months of age with peripheral lymph node enlargement

Question 11

T/F: for BLV to be transmitted, it has to be blood to blood because it can’t cross intact mucosa

Answer 11

true

Question 12

T/F: blood, milk, & colostrum are the main fluids associated with transmitting BLV to other animals

Answer 12

true

Question 13

T/F: relatively few new infections of BLV rarely occur in cattle older than 3-5 years

Answer 13

true

Question 14

if only 2-5% of cattle with BLV develop solid clinical tumors, what is the ‘loss’ associated with increased prevalence within a herd?

Answer 14

direct loss - death/culling, reproductive inefficiencies, & decreased milk production

indirect loss - loss of revenue from decreased export of breeding animals, loss of eradication & control, & decreased sales of semen & embryos

Question 15

T/F: AI is a cause of BLV transmission even if no injury to the mucosa occurs

Answer 15

false - has to be blood to blood transmission

Question 16

how is bovine enzootic lymphoma diagnosed in adult cattle?

Answer 16

ELISA for the gp-51 antigen on serum or whole blood - presence of antibodies to this antigen is positive for the virus (once infected always infected)

Question 17

how are calves diagnosed with bovine enzootic lymphosarcoma?

Answer 17

if under 3 months of age, test should be run on whole blood due to the potential of interference from maternal antibodies & then they should be checked again at weaning

Question 18

T/F: clinical signs of enzootic bovine lymphoma depends on the organs involved

Answer 18

true

Question 19

what organs are commonly involved in enzootic bovine lymphosarcoma?

Answer 19

right atrium, lymphadenopathy, abomasum, spinal column lymphatics & associated lymph nodes, uterus, & retro-bulbar

Question 20

what age of cows are typically affected by enzootic bovine lymphosarcoma?

Answer 20

3-5 year old cows

Question 21

T/F: for bovine enzootic lymphoma, infection rates increase with age & relatively few new infections happen after 3-5 years of age

Answer 21

true

Question 22

T/F: 70% of cattle that test positive for BLV show no clinical signs

Answer 22

true

Question 23

does a negative BLV test rule out neoplasia?

Answer 23

yes - look at other causes for clinical signs you are seeing

Question 24

what clinical signs may be seen in a cow that has BLV and a tumor on the right atrium?

Answer 24

right sided heart failure - brisket edema, jugular pulse/distension, +/- murmur

Question 25

what clinical signs may be seen in a cow that has BLV and lymphadenopathy?

Answer 25

enlarged pre-scapular, pre-femoral, & submandibular lymph nodes

weight loss

Question 26

what clinical signs may be seen in a cow that has BLV and a tumor in the abomasum?

Answer 26

melena, PLE, +/- abdominal pain

Question 27

what clinical signs may be seen involving the spinal column lymphatics & associated lymph nodes in a cow with BLV?

Answer 27

hind limb weakness/ataxia, localized neuro lesion to the spinal cord, sometimes can palpate through the rectum

Question 28

what clinical signs may be seen involving the uterus in a cow with BLV?

Answer 28

vaginal discharge, reproductive failure, & palpable problems upon rectal exam

Question 29

what clinical signs may be seen involving the eyes?

Answer 29

exophthalmus - retro-bulbar signs

Question 30

what are some rule-outs you should consider for BLV, if you’re concerned about the right atrium/lymphatics/abomasum/spinal column/uterus?

Answer 30

right atrium - high altitude disease, hardware, & endocarditis

lymphadenopathy - systemic infection/chronic inflammation

abomasum - abomasal ulcer/intussusception

spinal column lymphatics - trauma, diskospondylitis, degenerative disc disease, myelopathy

uterus - pyometra

Question 31

T/F: for BLV, FNAs of lymph nodes can be difficult because it can be hard to differentiate a neoplastic lymph node from a reactive lymph node

Answer 31

true

Question 32

what are the 3 basic strategies for control of BLV infection in cattle?

Answer 32

1. test & slaughter
2. test & segregation
3. test & implementation of corrective management

Question 33

why is test & slaughter not a realistic way of managing BLV?

Answer 33

can be very cost prohibitive to producers where the prevalence is high - dairy producers

may be feasible for beef cattle

Question 34

what is the most viable management option for BLV?

Answer 34

testing & implementing control strategies to decrease the transmission of disease - don’t see costs of segregation realized but can be hard to change routines