Caseous Lymphadenitis
Sheep & goats
Gram +ve facultative anaerobe & facultative intracellular bacillus
Corynebacterium pseudoteburculosis
(nitrate -/+ biotypes)
Nitrate +ve one is associated with ulcerative lymphangitis in horses & cattle
Caseous Lymphadenitis - pathogenesis
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
Caseous Lymphadenitis - transmission
Need to have a contaminated environment (e.g. wounds after fighting or shearing, traumatized oral/mucous membranes)
can be aerosol - pulmonary abscessation
Caseous Lymphadenitis - in environment
Doesn’t multiply in the environment but survives for weeks to months
e.g. shaded areas, wooded bedding
Caseous Lymphadenitis - prevalence
Prevalence increase with age
Clnical cases are sporadic
Subclinical common
goats»_space; sheep
Caseous Lymphadenitis - clinical signs
SUperficial lymph node abscesses in head & neck
Visceral lymph nodes - weight loss anorexia, depression
Sheep lamelated - goats pasty & green-y
Caseous Lymphadenitis - diagnosis
clinical signs, cytology & culture of abscesses
elisa, serology
(CBC unreliable)
Caseous Lymphadenitis - PM
Abcessed lymph nodes
Peripheral or visearl lymph nodes OR abscesses in lung parenchyma
Caseous Lymphadenitis - treatment
no a/b
drain abscesses, but may cause transmission
no yet reliable vaccine
irradicate infected animals
Leukosis
A. enzootic bovine leukosis or B. sporadic
Enzootic Leukosis bovine leukosis
bovine leukaemia virus
any tissue affected
once clinical, fatal
Enzootic Leukosis bovine leukosis
macrophages & lymphocytes in a pro-viral form
antibodies produced but not effective to the virus
Enzootic Leukosis bovine leukosis - Factors affecting prevalence
age level of infection in the herd status of the dam genetics concurrent disease or stress
Enzootic Leukosis bovine leukosis - transmission
mostly horizontal, blood
Enzootic Leukosis bovine leukosis - clin path
lymphocytosis in 30% of seropositives
Lymphoma is <5% of seropositives
Latent period
A. Enzootic Leukosis bovine leukosis 1. persistant lymphocytosis
Persistant lymphocytosis - sublicinical lymphoproliferative state (pre-lymphosarcoma) tumour associated antigen in the circulating cells
Enzootic Leukosis bovine leukosis 2. multi-centric lymphoma
greater than 2 years old, sporadically
depends on cli
Lymph node, retrobulbar, abomasal, heart, meninges, etc.
A. Enzootic Leukosis bovine leukosis 1. persistant lymphocytosis
CBC for cell count etc
Enzootic Leukosis bovine leukosis 2. multi-centric lymphoma
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
Enzootic Leukosis bovine leukosis - control
Can attempt eradication for control
sporadic bovine leukosis (name 3)
Juvenile multi-centril lymphoma
Cutaneous lymphoma
Thymic lymphoma
Juvenile multi-centril lymphoma
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
Cutaneous lymphoma
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
Thymic lymphoma
6 months to 2 years old
Clinical signs associated with a mediastinal mass
Venous obstruction edema, jugular distension, thoracic fluid –> interfere with ventilation