Chapter 5 Neoplastic Diseases

              

5.1 Marek's disease. 

Probably the most common of lympho-proliferative disease of chickens. characterized by mononuclear infiltration of peripheral nerve, the gonad, iris, visceral organs, muscle and skin.

• a. Synonyms: Fowl paralysis, range paralysis, polyneuritis Marek,1970), neuritis (Doyle, 1926), neurolymphomatoisi gallinarum (Pappenheimer et al. 1926), neuroganulomatois (Lercle and Fritizche 1934), acute leukosis.
• b. Etiology Cell associated DNA, herpes virus, COFAL and RIF tests negative.
• c. Occurrence: The disease had been observed in every major poultry producing country of the world. It attacks primarily young birds. Some broilers come down with the disease at 3 weeks of age. Losses due to mortality varies, estimated from 5 to 25% in affected flocks. Losses due to plant condemnation estimated to be around 200 million each year.
• d. Transmission:
  • 1. Marek's herpes virus is highly cell associated in the chicken cells. However, the virus escape through the confide skin epithelial cells. The virus could live in the dried epithelial cell outside of the chicken body for a few months. It is apparent that the infection is through the respiratory route.
  • 2 . Experimental infection could be accomplished by using whole blood or serum of birds with lymphoid tumor or without showing lymphoid tumor infected into one day old baby chicks. Injection or tumor cells can also reproduce the disease.
  • 3. According to experiment of the Burmester group in Eas Lansing, Miclligan, over 90% of the poultry flocks in the United States are infected with Marek's herpes virus. However, many birds do not develop tumor. Viremia persists for a long time as a source of infection.
  • 4. No evidence of transmission through the eggs.
• e. Factors affecting severity of this disease.
  • 1. Age at exposure: One to a few days old baby chicks are very susceptible.
  • 2. Amount of exposure: Heavier exposure resulted in higher percentage of infection.
  • 3. Genetic resistance: By selection of resistant strain of chicken.
  • 4. The virus can be easily killed by disinfectant.
• f. symptoms:
  • 1. Asymmetric progressive paresis of the leg, wing, or neck to total paralysis.
  • 2. In the beginning the affected leg may show inward curving of the toe, weakness, or incoordination. Later on, the bird has a tendency to hold one foot stretch forward or backward, a position which is quite characteristic.
  • 3. Paresis of the neck may be suggested by low carriage of the head and incipent torticollis, affection of the deep muscles and the nerves, especially the vagus, may lead to dilatation of the corp and gasping symptoms.
  • 4. Locomotory disturbances are often associated with systemic reactions, such as loss of weight, paleness, anorexia and diarrhea, although the appetite not infrequently remains good.
  • 5. Ascites, panting.
  • 6. Leg skin, purplish, red leg syndrome.
  • 7. Ocular, "gray eye", causing blindness, irregular shaped pupil. 
• g . Postmortem lesions:
  • 1. Gross lesions are indistinguishable from lymphoid leukosis.
  • 2. Characterized by localized or occasionally diffuse grayish soft wellings of the peripheral nerve trunks. The femoral portion of the sciatic trunk is commonly affected. Loss striation of the nerve fiber.
  • 3. Lymphoid tumors, focal or diffused in all major visceral organs and muscles.
  • 4. Skin involvement,sometimes skin turned purplish, with small lymphoid follicle tumors. Leg skin may also be affected.
  • 5. The bursa of Fabricius usually atrophic. However, some do develop diffuse thickening due to interfollicular distribution of tumor cells.
  • 6. Another characteristic is tumor in ovary (Cauliflower in appearance) and testicles.
  • 7. Microscopic appearance - The tumors are composed of various size and stages of lymphoid cells Plasma cells, small and medium lymphocytes, lymphoblasts, macrophages and R. E. cells.

In CNS, in addition to lymphoid infiltration, myelin degeneration and Schwann cell proliferation also noted.

• h. Prevention and control:
  • 1. Injection of Marek's tissue culture vaccine. A turkey herpes virus was isolated in 1968 from an apparently normal looking turkey, this virus was then adapted to tissue culture and a caccine was developed. By injection of the tissue culture vaccine subcutaneously or I-P. to one day old baby chicks, it offer protection for the chicken against tumor production. However, vaccination doesn’t t stop viremia of Marel's sherpe- virus.
  • 2 . Injection turkey blood drawn from turkeys with turkey herpes viremia.
  • 3. Genetic selection of resistance strain of birds.
  • 4. FAPp (Filtered Air Positive Pressure) Ventilation: Use biological filters to keep out viruses.
• i. Treatment:
  • No effective treatment. 

5.2 Leukosis group:

1. Etiology:

Caused by RNA (Oncorna virus) positive reaction to complement fixation test with avian leukosis viruses ( C O F A L test), and induce resistance to infection with Rous sarcoma virus (R I F + = Resistance inducing factor positive).

2. Types of manifestations.

• 1. Lymphoid leukosis (visceral lymphomatosis)
• 2. Erythroid leukosi (erthroblastosis).
• 3. Myeloid leukosis (myeloblastosis, myelocytomatosis).
• 4. Osreopetrosis (thick leg disease)
• 5. Rous sarcoma and other non-leukotic tumors.

5.2.1 Lymphoid leukosis:

1. Age:

• 16 weeks and older.

2. Transmission:-

• Primarily by carrier birds egg passage. direct contact, contaminated environment.

3) Clinical signs:

Comb pale, anemia, production stops (adult birds), emaciation. Enlarged abdomen (due to ascites), panting. Greenish diarrhea in terminal stages.

4) Postmortem Lesions:

• Often affects liver, spleen bursa Fabricius.
• Other organs such as kidney, lungs, gonad, heart,bone marrow, and mesentery were also affected.
• Lesions may be nodular, miliary or diffuse.
• No consistent or significant ghanges in the cellular elements of the circulating blood.

Histopathology:

The cytoplasm of most the tumor cells contain a large amount of RNA which stains red methyl pyronine, indicating the cells are immature and rapidly dividing. Intrafollicular infiltration of lymphoblasts in the bursa.

5 ) Diagnosis:

Based on flock history (previous leukosis outbreaks, age management (practices), and tumor confirmed by histopathology and differentiation from Marek's disease, pullorum, T.B., blackhead (enterohepatitis), coli granuloma, fatty liver disease.

Differential diagnosis:

(Lymphoid leukosisvsMarek'sdisease)  

 

COMPARISON	LYMPHOID LEUKO SIS	MAREK'S DISEASE
1. Age	16 weeks	4 weeks
2 Clinical	-	-
Signs(Paralysis or paresis	Absent	Present
3. Gross Lesions	-	-
Peripheral Nerve Involvement.	Absent	Present
Bursa Fabricius	Nodular tumor	Diffuse, enlarge-ment or atrophy
Skin and muscle tumor	Absent	Present
4. Microscopic lesions	-	-
Peripheral Nerve Infiltrate-ion	Absent	Present
Cuffing, white matter cere-bellum.	Absent	Present
Skin infiltration	Absent	Present
Cell proliferation in bursa Fabricius	Intra-follicular	Inter-follicular
Cytology of lymphoid cells	Uniform, blasts	Plemorphic

6) Control methods

• No absolute way of prevention or control .
• Eradication by testing all breeders and slaughter of infected flocks.
• Use only LL - free breeders.
• Breed leukosis resistant strain.

7) Treatment:

• No effective treatment.

5.2.2 Erythroblastosis:

1) Occurrence :

Comparatively rare sporadic occurrence under field conditions.

2) Symptoms:

• Age: 6 months and older. 
• Paleness, yellowish color of the unfeathered parts of the body.
• Stupor and diarrhea.
• Emaciation and loss of egg production.
• Uncontrollable bleeding from the feather follicles.

3) Lesions:

Petechial hemorrhage in mucosa of the small intestine, under the liver capsule, or in the subcutaneous tissue. Diffuse enlargement of liver, kidney and especially the spleen, associated with a cherryed discoloration on fresh specimens. 

Hematology	Plasma	Leukocyte	Erythrocyte
Normal Blood	55	1	44
Erythroblastic Blood	88	1	11
Granuloblastic Blood	16	69	15

(Plasma: Leukocyte: Erythrocyte ratio)

In case of erythroblastosis gives evidence of severe anemia, blood picture characterized by the appearance of many basophil erythroblasts, and erythrogonia, which are considered to be hemoglobin-free precursors of erythrocytes.

5.2.3 Myeloblastosis:

l) Occurrence:

There is no essential difference between myeoblastosis and erythroblastosis.

2) Pathology:

In distinction from erythroblastosis, the disease has a tendency to bring out grayish mottling of the enlarged parenchymatous organs.

3) Hematology:

Characterized by the appearance of primitive cell of the myeloblastic series, especially myeloblasts and prpromyelobytes in large number, up to 2 million per cu. mm.

5.2.4 Myelocytomatosis, aleukemic myeloid leukosis sporadic disease.

l) Occurrence.

2) Pathology.

Tumor with a yellowish-white color, resembles congealed cream in appearance and consistency, and are often of multiple anatomical origin.

Histologically, the tumor consists of compact masses of myelocytes which are strikingly uniformed in appearance and have the typical full acidophil granulation of either the mature eosinophil or the heterophil.

3) Hematology:

Uncomplicated cases are usually aleukemic, although there may be a heterophils leukocytosis. Appearance of polychromic myelocytes and acidophilic metamyelocytes.

5.2.5 Osteopetrosis:

l) Age: 8-12 weeks.

2) Clinical signs.

• The long bones of the limbs are often affected.
• Uniform or irregular thickening of the diaphyseal or metaphyseal regions.

3) Lesions:

Common in tibia and/or tarsometatarsus. The periosteum over the lesion is greatly thickened due to an increase in number and size of basophilic ostebblasts. Lesion more common in male than female.

5.2.6 Sarcoma group:

Connective tissue tumors with evidence of transmissibility and viral etiology. They include fibrosarcoma, fibroma, myxosarcoma,myxoma, histiocytic sarcoma, osteoma, osteogenic sarcoma and chondrosarcoma.

The rous sarcoma virus(RSV) was isolated after extensive transplantation. It includes a variety of tumors, in addition

The tumors are composed of spindle-cells and myxosarcoma that metastasized and kill the host within 7-to- 21 days. The tumor can be produced experimentally in some laboratory rodents, dogs, and primates.

5.2.7 Reticuloendotheliosis:

The "T" virus was isolated from adult turkeys with leukosis-like lesions caused a consistent, rapid, and marked reticculoendotheliosis following inoculation into young chickens, turkeys, and Japanese quail.

There was a high mortality, and affected birds had markedly enlarged livers and spleens. There is no evidence that there is a naturally occurring disease associated with this virus in commercial poultry.

The "T" cirus (REV) is basically similar to the RNA-containing viruses of the myxovirus group.

E. Hephyoblastoma

These are frequently large tumors in the abdomen that have a stalk attached to the kidney or are just anterior to the kidneys. They may be firm and fibrous or meaty or cystic and contain clean of hemorrhagic fluid.

Histologically, there is a neoplastic proliferation of both epithelial and mesenchymal elements. Epithelial elements: Enlarged tubules and malformed glomeruli (adencarcinoma). Some with predominated tubules (cystadenoma). 

5.3 Tumors of unknown etiology:

From an economic and public health view,these tumors are of minor significance.

5.3.1 Central nervous system.

• Avian astrocytoma (avian flioma). (Benign).
• Transitory torticollis, retropulsion, incoordination etc. in adult birds. Sharply delineated whitish area at the base of the cerebellum or thalalnus.

5.3.2 Integument.

• 1. Hemangiopencytoma (benign).

Small subcutaneous nodules, white in color. The histologic appearances a spindle cell sarcoma with rattler striking, concentrically arranged cells. (Silver stain).

• 2. Squamous cell carcinoma (epithelioma, epithelioblastoma, epidernoid).
• 3. Trichoepithelioma (benign cystic epithelioma).

5.3.3 Urogenital system.

• 1. Ovarian carcinoma (adenocarcinoma) carcinoma leiomyomatosum). The most common tumor of unknown etiology of the hen. The tumor occur in Mature hen, at least 1 year of age. Numerous white firm discrete coalesing tumors on the serosal surfaces of the abdominal viscera. There is massive involvement of the duodenal loop and pancreas .

Histopathology:

• 1.Corlike acini lined by a single layer of cuboidal epithelium.
• 2. Fallopian tube carcinoma or oviduct carcinoma. Cystadeno-carcinoma occurring in the epithelial portion of the infundibulum and majnum.
• 3. Granulosa cell (granulosa-theca cell tumor).
• 4. Arrhenoblastoma. (rare.)

5.3.4 Digestive System:

• 1. Bile duct adenoma
• 2. Hepatoma