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Renal Tumors

Other Names: Nephroblastomas, Embryonal Nephromas, Kidney Tumors

Nephroblastomas, also known as embryonal nephromas, are the most commonly reported renal tumor in chickens, and frequently associated with the avian leukosis virus (ALV). Renal carcinomas, adenoma, cystadenoma, fibrosarcoma, lymphosarcoma, and other neoplasms can also occur.

Clinical Signs


The predominant clinical sign that points towards the possibility of renal tumor is unilateral or bilateral leg lameness or paralysis, with no history of trauma. The chicken may still be able to move their leg from front to back, but just can't stand on it. This clinical sign results from compression on the ischiadic nerve by the mass of the tumor.

The musculature in the affected leg(s) may atrophy from disuse, and the entire leg may become paretic. Affected birds may have trouble resting or sleeping due to discomfort. Their appetite, however, often remains relatively normal. Other less specific clinical signs which may occur are abdominal enlargement, apathy, weight loss, dyspnoea, and diarrhea, resulting from the intracoelomic pressure or organ displacement. Once clinical signs develop, most chickens can live an additional 3 to 6 months if they're provided proper palliative care.

Diagnosis


  • Radiographs: Are useful in assessing the size, location, and radiopacity of the kidneys. Two views are recommended---right or left lateral and ventrodorsal. Correct patient positioning is essential.
  • Ultrasound: Can be useful if the patient has ascites, which compresses the air sacs, allowing the ultrasonographic imaging of the kidneys. Otherwise, the presence of the air sacs makes it difficult to view kidneys in birds using ultrasound imaging.

Treatment


In mammals, nephrectomy is the treatment of choice for unilateral renal tumors. However, this is not the case in birds. Surgical removal of kidneys in birds is virtually impossible due to their location and intricate relationship with the surrounding blood vessels and nerves. There are also no effective medical management options for renal tumors in birds. Palliative care through the use of analgesics for pain management (for nerve compression by the renal mass), corticosteroids, and special care for immobility may help make the remainder of their lives more comfortable. Ultimately, euthanasia must be considered once husbandry modifications and analgesia fail to ensure appropriate quality of life for the bird.

Clinical Signs

Unilateral lameness
Ataxia
Paralysis
Diarrhea
Weight loss
Abdominal distension
Muscle atrophy

Diagnosis

  • History
  • Clinical signs
  • Radiographs

Reported Cases

  • Case 1: Renal adenocarcinoma in a Budgie. Two female budgerigars had a history of gradual emaciation. One bird also had abdominal distention and a paralyzed left leg. Histologically, the tumors appeared to be adenocarcinomas. Ref
    Primary tumor site: kidneySites of Metastases: none

  • Case 2: Renal adenocarcinoma in a Cocktatiel. A 7-year-old cockatiel presented with a 1 week history of right leg lameness. A renal adenocarcinoma invading and constricting the right ischiatic nerve resulted in disuse atrophy of the affected leg and radiographic evidence of osteopenia. Ref
    Primary tumor site: kidneySites of Metastases: none

  • Case 3: Renal adenocarcinoma in a Eagle. A 33-year-old captive male golden eagle was presented for necropsy with a history of emaciation and depression. The liver was severely distorted by numerous, coalescent, poorly demarcated, white firm nodules. Upon microscopic examination, these masses were found to be infiltrative and were composed of anastomosing tubular structures lined by signettiring cells piling up in a disorderly fashion. Ultrastructurally, neoplastic cells were characterized by abundant microvilli at their apical pole and by numerous junctional complexes on lateral cell membranes. Based on morphological criteria, this tumor was classified as a poorly differentiated cholangiocellular carcinoma. Metastases were found in kidneys, testes, lungs, air sacs, pericardium, pancreas, adrenals and meninges. Additionally, two (11 and 2 mm) beige nodules were found in the cranial portion of the left kidney. Histological examination revealed locally infiltrative compact masses composed of well-differentiated tubules lined by a tall columnar epithelium without microvilli. These tumours were diagnosed as renal tubular adenocarcinomas. Ref
    Primary tumor site: kidneySites of Metastases: testes, lungs, air sacs, pericardium, pancreas, ad

  • Case 4: Renal adenocarcinoma in a Japanese quail. A 2-year-old female Japanese quail, stopped laying eggs and showed signs of weight loss and ascites followed by death. Necropsy revealed that macroscopically, she had a whitish left lung, whitish masses measuring 1.0 cm in diameter in the caudal right lobe of the liver and in the gizzard serosa; 0.1-0.5cm masses in the mesentery and intestinal serosa; and a 5.0x2.0cm mass in synsacral area that encompassed 90% of the renal parenchyma and part of ovary and oviduct. Histologically, epithelial cells proliferation with formation of tubules, sometimes without lumen supported by mild fibrovascular stroma and multifocal necrosis was observed in the renal mass. The neoplastic cells were cuboidal, with round to oval nuclei, and evident nucleolus, abundant eosinophilic cytoplasm, moderated pleomorphism. Mitotic figures were rare. Metastasis was seen diffuse in ovary, oviduct, left lung, multifocal in intestinal serosa, focal in liver and serosal and muscular layer in gizzard. Immunohistochemically, tumors cells were positive for cytokeratin (clones AE1+AE3) and negative for cytokeratin 5/6, CD10 and placental alkaline phosphatase. Ref
    Primary tumor site: kidneySites of Metastases: ovary, oviduct, left lung, multifocal in intestina

  • Case 5: Renal tubular adenoma in a Toucan. An adult male channel-billed toucan was presented with a history of weakness, dyspnea, and severe dilatation of the coelomic cavity, which was caused by accumulation of serohemorrhagic fluid. Radiographs revealed increased radiodensity and thickness of the descending aorta and a pectoral mass, and blood test results revealed anemia, hypocalcemia, hypoproteinemia, and hyperuricemia. On ultrasound examination, a hyperechoic enlarged soft tissue mass was found in the caudodorsal region of the coelom. The bird did not respond to supportive care and died. Postmortem examination revealed severe, bilateral nephromegaly due to multifocal to coalescing renal tubular adenomas (adenomatosis), which was complicated with renal gout and soft tissue mineralization. Relevant concurrent diseases included hepatic hemochromatosis, subcutaneous cestodiasis with cellulitis, and systemic amyloidosis. Ref
    Primary tumor site: kidneySites of Metastases: coelum

Treatment

NameSummary
Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Provide additional vitamins and probiotics. Limit stress. Call your veterinarian.
Methylprednisolone20 mg/kg as a palliative therapy. However, should be used with caution, since corticosteroids predispose chickens to secondary disease.
Pain managementAnalgesics and/or low-level laser therapy (660 nm, 9 J/cm squared).
Omega 3 fatty acidsAdded to the diet at 0.22 ml/kg. Concurrently add 160 mg/kg of Vitamin E (since the bird's requirements for dietary vitamin E will increase.O Cojean et al., 2020

Support

Prevention

Ensure all birds receive the Marek's Disease vaccine.

Prognosis

Poor

Scientific References

Risk Factors

  • Infection with avian leukosis virus or Marek's disease virus.
  • Not getting chicks vaccinated against Marek's disease.

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