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Ovarian Tumors

Ovarian cancer, and other reproductive tract neoplasia, occur frequently in domestic hens, especially in high egg producing breeds. Up to 30 to 35% of domestic hens develop ovarian cancer by the time they are 2.5 years old (Fredrickson,1987). As a result of this frequency, hens were used as an animal model for ovarian cancer in woman.

The reproductive system of the hen includes two ovaries (left and right) and an oviduct.
Ovarian cancer chickens
Only the left ovary is functional, which is located in the coelomic cavity adjacent to the rostral end of the left kidney. The oviduct consists of five regions: the infundibulum (fertilization), magnum (deposition of albumen), isthmus (deposition of membranes), uterus (shell), and vagina (transport to cloaca). An actively reproducing laying hen maintains 5 or 6 large, yolk-filled follicles with diameters increasing from 8 to 40 mm, comprising a pre-ovulatory hierarchy.

After reaching sexual maturity around 18-20 weeks of age, laying hens ovulate approximately every 24 hours. By the time they are 2 years old, most hens have experienced several hundred ovulations, which is the equivalent to that of a woman approaching menopause. It is this “incessant ovulation” which puts hens at such a high risk for spontaneously developing adenocarcinomas in the ovarian surface epithelium. Because laying hens are kept in a continuous state of active reproduction, small follicles undergo continuous atresia.

Early tumors of the ovary consist of small, round, white, and firm nodules on the ovarian surface, which may be mistaken for atretic follicles. As it progresses, the tumors coalesce into a gray-white, firm cauliflower-like mass. Ascites (accumulation of fluid in the abdomen) usually develops when such tumorous growth is extensive. The walls of affected intestines become thickened and adhere together as a result of the inflammation, and the intestinal lumina become constricted. At this stage, hens are usually extremely thin, and assume an upright, penguin-like position due to the discomfort.

Cancer of the oviduct is usually caused by adenocarcinomas, which develop on the ovary as well as the mesentery and pancreas, which can make it difficult to distinguish whether the primary tumor started in the ovary or the oviduct. Most adenocarcinomas of the oviduct originate in the upper magnum and are extremely malignant. Even if the tumor is small, it often penetrates through the muscularis and spreads through the abdominal cavity via tunnels between the celomic membranes. From there, it spreads to the intestinal serosa, especially the pancreas and duodenum, because they lie deep in the ventral abdominal cavity.

Clinical Signs


Hens with ovarian/oviductal cancer may have a history of egg binding, oviductal prolapse, and/or laying abnormal eggs (soft-shelled, shell-less, etc). Ascites is usually observed in late-stage cases. This results in an abnormal build-up of fluid in the abdomen, causing discomfort, pain, problems with mobility and breathing, and other symptoms that decrease the quality of life.

Treatment


There is no available cure for ovarian tumors in hens. Treatment options are aimed at stopping egg production and to minimize risk of future egg-related infections such as egg yolk peritonitis. These include hormone implants or surgery. There are also a number of different natural herbs which have shown some benefit in slowing down the progression of the disease.

Clinical Signs

Ascites
Enlarged abdomen
Difficulty breathing
Pasting of vent
Upright, penguin-like position
Shell-less eggs
Abnormal eggs
Change in behavior

Diagnosis

  • History
  • Clinical signs
  • Physical exam
  • Ultrasound
  • Radiographs

Reported Cases

  • Case 1: Ovarian adenocarcinoma in a Chicken Ovarian adenocarcinoma was detected in a 3-year-old hen from a backyard flock. The hen had been declining in general health. The hen had very depleted skeletal muscle stores and no body fat. The coelomic cavity had an excess of clear, transparent yellow fluid and numerous firm, pale, and yellow nodules up to 2 cm diameter. The ovary was the site of confluent nodules, and the site of the primary neoplasm. The histologic diagnosis was adenocarcinoma of the ovary, with carcinomatosis throughout the coelomic cavity. This neoplasm is one of the more common neoplasms of older hens. Ref

  • Case 2: Ovarian carcinoma in a Cockatiel. An ovarian carcinoma was diagnosed in a 17-year-old cockatiel that died after several days of depression and respiratory difficulty. Post-mortem examination revealed a large firm and multinodular mass replacing entirely the ovary. Histologically, this mass was found to be an ovarian carcinoma which had also produced metastasis in multiple internal organs, including, heart and liver. Ref
    Primary tumor site: ovarySites of Metastases:

  • Case 3: Ovarian neoplasia in a Cockatiel. Long-term medical therapy of 2 cockatiels eventually diagnosed with ovarian neoplasia is described along with responses to the treatment regimens. Each bird had initial signs consistent with reproductive disease (chronic egg laying, ascites, and lethargy) and respiratory distress. The diagnosis of ovarian adenocarcinoma was confirmed on postmortem examination of both birds. The birds were conservatively managed by periodic coelomocentesis and gonadotropin-releasing hormone (GnRH) agonist administration for 9 and 25 months, respectively. A positive response to GnRH agonist therapy was documented in 1 of the 2 birds. These 2 cases demonstrate that periodic coelomocentesis with or without GnRH agonist therapy may be a viable option for the long-term management of ovarian neoplasia and reproductive-organ-associated ascites in cockatiels. Ref
    Primary tumor site: ovarySites of Metastases:

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. Limit stress. Call your veterinarian.
Hormone implantsSuprelorin®, Virbac is used off-label to stop ovulation (egg production) in hens.
SurgerySalpingohysterectomy (surgical removal of the oviduct)
Flaxseed10% flaxseed supplemented to the daily diet may help decrease the severity.K Ansenberger et al., 2010
Curcumin (Curcuma longa)12 months of dietary curcmin intake at 26 or 53 mg/day led to marked dose-dependent reductions (about 31% and 57%, respectively) in ovarian cancer (serous and mucinous) incidence in hens. Daily curcumin intake also resulted in tumors that were markedly smaller than those hens who did not receive curcumin in their diet.K Sahin et al., 2018
AspirinSupplemented as 0.1% overall diet, may inhibit the progression of ovarian cancer.M.E.Urick et al, 2009
LycopeneSupplemental lycopene given at 200-400 mg/kg per day significantly reduced the overall ovarian tumor incidence (P < 0.01) as well as the number and the size of the tumors (P < 0.004 and P < 0.005, respectively). Lycopene also significantly decreased the rate of adenocarcinoma, including serous and mucinous subtypes (P < 0.006)K Sahin et al., 2018; E Yilmaz et al., 2020
Ginger (Zingiber officinale)J Rhode et al., 2007 discovered that ginger inhibits growth and modulates secretion of angiogenic factors in ovarian cancer cells, and could potentially aid in the treatment and prevention of ovarian cancer. Ginger has also been studied for it's use as an antioxidant in chickens, when given as 5 g/kg of diet per day.J Rhode et al., 2007; G Zhang et al., 2009; C Wen et al., 2019; A Akbarian et al., 2011; X Zhao et al., 2011
Genistein (Genista tinctoria)F Erten et al., 2021 found that when laying hens were given 400-800 mg/kg of genistein per day, it exhibited an anticancer effect by reducing pro-inflammatory biomarkers levels and inhibiting GSK-3 expression in the ovaries of old laying hens. It acts in a dose-dependent manner.F Erten et al., 2021

Support

Prevention

Hormone implants (Suprelorin®, Virbac) to stop egg production.

Prognosis

Poor

Scientific References

Age Range

Occurs usually in mature egg laying hens over 2 years of age

Risk Factors

  • Chronic egg laying
  • Increased age
  • High egg producing breeds

Case Stories

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