Disorders of the Equine Hemolymphatic System III

Lymphoma

What is the most common neoplasia of horses?

Lymphoma

Hematopoietic neoplasia arising from lymphoid tissue

B

T or F: Lymphoma is a disease of older horses

1. Multicentric

2. Intestinal

3. Mediastinal

4. Cutaneous

What are the different clinical syndromes of lymphoma based on anatomic distribution?

1. Anatomic location

2. Morphologic

3. Cell lineage

How is lymphoma classified?

Immunohistochemical evaluation

How do we determine the cell lineage of lymphoma?

T cell rich, large B cell lymphoma

What is the most common cell lineage of equine lymphoma?

1. Weight loss

2. Anorexia

3. Lethargy, depression

4. Edema

5. Recurrent fever

6. Lymphadenopathy

What are the most common clinical signs of lymphoma? (6)

A (you can only feel 1 peripheral LN)

T or F: Peripheral lymphadenopathy is rare in horses

Lymphopenia

The leukogram varies for lymphoma, which is more common? Lymphopenia or lymphocytosis

Hypoproteinemia

____________________ can occur from GI loss if there is GI lymphoma

1. Hypercalcemia

2. IMHA or IMTP

What are some paraneoplastic syndrome hematologic abnormalities that can be observed?

Multicentric lymphoma

Lymphoma involving multiple LNs and extra-nodal metastasis with nonlymphoid tissue involvement (spleen and liver most common)

A

T or F: Multicentric has a very poor prognosis

1. Malabsorption, protein loss

2. Weight loss

3. Edema

4. Abdominal effusion

5. Colic/diarrhea

What are clinical signs of intestinal lymphoma? (5)

1. Diffuse/segmental thickening

2. Focal masses

3. Scattered ulcerative lesions

What neoplastic lesions can be seen with intestinal lymphoma?

Intestinal lymphoma

What is the most common neoplasia of the equine gastrointestinal tract?

1. Ultrasound, rectal biopsy

2. Abdominal fluid analysis (?)

3. +/- glucose absorption test

How do you diagnose intestinal lymphoma?

Thoracic lymphoma

What is the most common thoracic neoplasia of horses?

1. Mediastinal

2. Thymic

3. Pulmonary

What are the different types of thoracic lymphoma?

T cell

(B cell or T cell) predominates for thoracic lymphoma in horses

1. Nasal discharge

2. Abnormal lung sounds, dyspnea

3. Pleural effusion

4. Ventral thoracic and limb edema

5. Lymphadenopathy

What are clinical signs of thoracic lymphoma in horses? (5)

Cutaneous lymphoma

Skin associated lymphoid tissue with lymphoma

A

T or F: Cutaneous lymphoma can have single to multiple firm, subcutaneous, nonpainful masses

T cell rich, large B cell lymphoma

Cutaneous lymphoma is predominantly what cell lineage?

B

T or F: Cutaneous lymphoma is very aggressive

Corticosteroids or surgical excision

Cutaneous lymphoma is often responsive to what treatments?

Hormonal changes (pregnancy)

__________________ may influence the recurrence of cutaneous lymphoma

1. Palpable mass or lymphadenopathy

2. Ultrasound (mass identified)

3. Fluid cytology (pleural or peritoneal)

4. Excisional biopsy or FNA

5. Bone marrow aspirate

6. Flow cytometry (immunophenotyping or serum IgM)

Antemortem diagnosis of lymphoma is often challenging, what are your diagnostic options? (6)

Palliative, curative

Lymphoma treatment is typically ______________ and not _______________

1. Radiation therapy (brachytherapy, linear accelerator)

2. Corticosteroids (alone or with chemotherapy)

3. Chemotherapy (very expensive)

4. Intralesional

What is involved in lymphoma treatment in horses?

Cisplatin

What drug is used for intralesional cutaneous lymphoma treatment?

Primary leukemia

Leukemia originates from bone marrow

Secondary leukemia

Leukemic phase of lymphoma

Leukemic leukemia

Leukemia with profound leukocytosis

Subleukemic leukemia

Leukemia with blast cells and low/normal WBC

Aleukemic leukemia

Leukemia with abnormal bone marrow only

Grave

Leukemia has a _____________ prognosis

1. Anemia

2. Thrombocytopenia

3. Increased blast (or atypical) cells in blood

What are the most common hematologic changes for equine leukemia?

1. Bone marrow aspirate

2. Flow cytometry (cellular antigens)

3. Immunohistochemistry, immunophenotyping

How do you diagnose leukemia?

Primary myeloma

Plasma cell proliferation in the bone marrow

Myeloma

Plasma cell proliferation

Secondary myeloma

Plasma cell proliferation extramedullary - LN, spleen, kidney, liver

Multiple myeloma

Plasma cell proliferation in bone marrow and tissues

1. Weight loss

2. Fever

3. Lethargy

4. Pale MM

5. Limb edema

6. Recurrent infection

What are clinical signs of myeloma in horses? (6)

1. Bone marrow - plasmacytosis

2. Hematology

How do you diagnose myeloma?

1. Anemia

2. Hyperglobulinemia

3. Pancytopenia

4. Hypercalcemia

5. Monoclonal immunoglobulinemia

What will you see on hematology for myeloma? (5)

A

T or F: Equine myeloma has a poor prognosis and rapid deterioration

Pigeon fever

What is another name for Corynebacterium pseduotuberculosis?

Corynebacterium pseudotuberculosis

What is the etiology of pigeon fever?

Southwest US

Pigeon fever is endemic where?

Dry and dusty

What type of conditions are good for pigeon fever?

B (only certain states)

T or F: Pigeon fever is reportable in all states

Mechanical vectors - flies

How is Corynebacterium pseudotuberculosis transmitted?

Ventral midline

Corynebacterium pseudotuberculosis bacteria enter via wounds/abrasions in the skin or mucous membranes with the _________________ being predisposed

1. Ulcerative lymphangitis

2. Internal infection

3. External abscesses

What are the three clinical presentations of Pigeon fever?

1. Ulcerative lymphangitis

2. Internal infection

Of the clinical presentations of pigeon fever, which require aggressive treatment?

Ulcerative lymphangitis

What is the least common clinical presentation of pigeon fever?

External abscesses

What is the most common clinical presentation of pigeon fever?

Ulcerative lymphangitis

Clinical presentation of pigeon fever characterized by severe limb swelling, cellulitis and draining tracts

Hind

Ulcerative lymphangitis from pigeon fever most commonly affects (fore or hind) limbs

Internal infection

Clinical presentation of pigeon fever characterized by infection in the liver, spleen, kidney and lungs

External abscesses

Clinical presentation of pigeon fever characterized by single-multiple well encapsulated abscesses with odor-free tan exudate

Culture of aspirate or exudate

How do you diagnose external abscesses for pigeon fever?

1. Clinical signs

2. Diagnostic imaging

3. +/- transcutaneous biopsy/aspirate

4. Synergistic hemolysis inhibition test (SHI)

How do you diagnose internal infection for pigeon fever?

Clinical signs

The synergistic hemolysis inhibition test (used to diagnose internal infection of pigeon fever) should be interpreted in light of ________________

B

T or F: You should use a synergistic hemolysis inhibition test (SHI) as a sole diagnostic test for internal infection of pigeon fever

Establish drainage

How do you treat external abscesses from pigeon fever?

B (may prolong course of disease)

T or F: Antimicrobial therapy is recommended for external abscesses from pigeon fever

1. Ulcerative lymphangitis

2. Internal abscesses

3. Systemic illness

When is antimicrobial therapy recommended for when treating for pigeon fever?

1. Rifampin and ceftiofur/penicillin

2. TMS

3. Enrofloxacin

What antimicrobial drugs can be used to treat for pigeon fever?

1. Hydrotherapy

2. Exercise

3. Drainage

4. Wraps

5. NSAIDs

What is included in supportive care for pigeon fever? (5)

1. Reduce environmental contamination

2. Insect control

How do you prevent pigeon fever?