Lymphoid Disease in Ruminants

Question 1

Caseous Lymphadenitis

Answer 1

Sheep & goats
Gram +ve facultative anaerobe & facultative intracellular bacillus
Corynebacterium pseudoteburculosis
(nitrate -/+ biotypes)
Nitrate +ve one is associated with ulcerative lymphangitis in horses & cattle

Question 2

Caseous Lymphadenitis - pathogenesis

Answer 2

outer cell wall = lipid layer
Resists phagocytic killing
Phospholipase D - exotoxin, cytotoxin, partial hemolysin, causes local inflammation & necrosis
Causes lymphatic thrombosis
Penetrates the skin
Leukocytes phagocytose the bacteria (survive)
Go to lymph node & multiply
cells die, release, lymphogenous & hematogenous spread

Question 3

Caseous Lymphadenitis - transmission

Answer 3

Need to have a contaminated environment (e.g. wounds after fighting or shearing, traumatized oral/mucous membranes)
can be aerosol - pulmonary abscessation

Question 4

Caseous Lymphadenitis - in environment

Answer 4

Doesn’t multiply in the environment but survives for weeks to months
e.g. shaded areas, wooded bedding

Question 5

Caseous Lymphadenitis - prevalence

Answer 5

Prevalence increase with age
Clnical cases are sporadic
Subclinical common
goats&raquo_space; sheep

Question 6

Caseous Lymphadenitis - clinical signs

Answer 6

SUperficial lymph node abscesses in head & neck
Visceral lymph nodes - weight loss anorexia, depression
Sheep lamelated - goats pasty & green-y

Question 7

Caseous Lymphadenitis - diagnosis

Answer 7

clinical signs, cytology & culture of abscesses
elisa, serology
(CBC unreliable)

Question 8

Caseous Lymphadenitis - PM

Answer 8

Abcessed lymph nodes

Peripheral or visearl lymph nodes OR abscesses in lung parenchyma

Question 9

Caseous Lymphadenitis - treatment

Answer 9

no a/b
drain abscesses, but may cause transmission
no yet reliable vaccine
irradicate infected animals

Question 10

Leukosis

Answer 10

A. enzootic bovine leukosis or B. sporadic

Question 11

Enzootic Leukosis bovine leukosis

Answer 11

bovine leukaemia virus
any tissue affected
once clinical, fatal

Question 12

Enzootic Leukosis bovine leukosis

Answer 12

macrophages & lymphocytes in a pro-viral form

antibodies produced but not effective to the virus

Question 13

Enzootic Leukosis bovine leukosis - Factors affecting prevalence

Answer 13

age
level of infection in the herd
status of the dam
genetics
concurrent disease or stress

Question 14

Enzootic Leukosis bovine leukosis - transmission

Answer 14

mostly horizontal, blood

Question 15

Enzootic Leukosis bovine leukosis - clin path

Answer 15

lymphocytosis in 30% of seropositives
Lymphoma is <5% of seropositives
Latent period

Question 16

A. Enzootic Leukosis bovine leukosis 1. persistant lymphocytosis

Answer 16

Persistant lymphocytosis - sublicinical lymphoproliferative state (pre-lymphosarcoma) tumour associated antigen in the circulating cells

Question 17

Enzootic Leukosis bovine leukosis 2. multi-centric lymphoma

Answer 17

greater than 2 years old, sporadically
depends on cli
Lymph node, retrobulbar, abomasal, heart, meninges, etc.

Question 18

A. Enzootic Leukosis bovine leukosis 1. persistant lymphocytosis

Answer 18

CBC for cell count etc

Question 19

Enzootic Leukosis bovine leukosis 2. multi-centric lymphoma

Answer 19

lymph nodes are unreliable (don’t test those
Do a post mortem & serology)
Aged serology - high sensitivity/specificity, but you may get false negatives & false positives
Can use RAA/Virus isolation/PCR

Question 20

Enzootic Leukosis bovine leukosis - control

Answer 20

Can attempt eradication for control

Question 21

sporadic bovine leukosis (name 3)

Answer 21

Juvenile multi-centril lymphoma
Cutaneous lymphoma
Thymic lymphoma

Question 22

Juvenile multi-centril lymphoma

Answer 22

Cavles under 6 months
sudden onset, rapid course of disease
weight loss, depression, lymphadenopathy or variable signs depending on organs
If bone marrow infiltrates - anemia leukaemia

Question 23

Cutaneous lymphoma

Answer 23

Dermal lesions, back hind limbs & perineum
May become multi centric lymphoma
Occurs in animals 1-3 years old
lesions are 1-3 cm with a necrotic centre
May regress & reoccur

Question 24

Thymic lymphoma

Answer 24

6 months to 2 years old
Clinical signs associated with a mediastinal mass
Venous obstruction edema, jugular distension, thoracic fluid –> interfere with ventilation