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Ascites Syndrome

Other Names: Waterbelly, Pulmonary Hypertension Syndrome

Ascites syndrome is one of the most common causes of mortality in commercial flocks of broilers. It shouldn't be confused with the general term, 'ascites', referring to the accumulation of fluid in the peritoneal cavity. Ascites syndrome is a cardiovascular disease unique to broilers, as it is directly linked to their rapid growth rate.

Ascites syndrome occurs as a result of right-heart congestive heart failure and valvular insufficiency. The growth rate of modern day commercial broiler breeds has quadrupled since the 1950s. Their body composition has changed dramatically, especially the relative size of the pectoral muscles. This has numerous repercussions on the endocrine physiology. Their internal organs aren't able meet the increased metabolic demands required by their bodies (especially during the period of rapid juvenile growth, when the metabolic rate is already very high). A higher oxygen demand from the anabolic processes, together with high requirements, exceeds the capacity of their respiratory and cardiovascular system, triggering the events leading to heart failure.
Signs of Ascites Syndrome in chickens
Several environmental factors contribute to the onset of ascites syndrome. These include being raised at a high altitude, exposure to stressful living conditions (such as overcrowing, poor ventilation, or cold or hot temperatures), and feed management.


There are several diagnostic tests which can be performed to help diagnose ascites syndrome in chickens.
  • Abdominal fluid analysis: Fluid is usually clear, but can also be cloudy with fibrin clots.
  • Radiographs: Loss of abdominal detail and an enlarged cardiac and/or cardiohepatic silhouette.
  • Electrocardiography: Decreased heart rate, with an increase in S-wave amplitude and ventricular fibrillation associated with right-heart dilation and a right deviation of the mean electrical axis (which becomes negative).
  • Echocardiography: Right and left atrioventricular valves regurgitation, reduction in fractional shortening of the left ventricle, dilation of cardiac chambers, and pericardial effusion.

Gross Lesions

Gross lesions may include dilated and hypertrophic right ventricle, ascites, pericardial effusion, pericarditis, organ congestion, dilation of pulmonary veins, and a fibrotic liver when chronic.

Clinical Signs

Abdominal distension
Difficulty breathing


  • History
  • Clinical signs
  • Abdominal fluid analysis
  • Radiographs
  • Echocardiography
  • Electrocardiography

Reported Cases

  • Case 1: Ascites syndrome in a Chickens A naturally occurring cardiomyopathy in broiler chickens from a single Ontario farm was studied in order to define the morphologic changes. Gross and histologic features of affected birds were compared with those in age-matched control penmates. Body weight and weight and volume of individual cardiac chambers were measured. Histologic sections of 18 different tissues were examined, and lesions observed were scored subjectively. Affected birds were stunted and had marked right ventricular dilation and hypertrophy, atrial hypertrophy, ascites, pulmonary congestion and edema, and hepatic capsular fibrosis. Microscopic changes in the heart of affected birds were mild and did not suggest a specific cause of heart failure. Lungs had marked hypertrophy of parabronchial smooth muscle and collapse and apparent loss of associated air capillaries. Other histologic changes observed were thought to be the result of passive congestion of viscera caused by right heart failure and chronic debility. Ref


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.
Enalapril30-60 ppmM Fathi et al., 2015
Furosemide0.5-1 mg/kgBeaufrère, H et al., 2015
Imidapril3 mg/kg once dailyX Hau et al., 2014.
CoQ1020-40 mg/kgA Geng et al., 2010; M Nemati et al., 2017
Elecampane (Inula helenium) rhizome500-2000 mg/kg dietM Abolfathi et al., 2020
Garlic (Allium sativum) bulb extract5 g/kg dietS Varmaghany et al., 2015
Hawthorn (Crataegus oxyacantha) extract0.1-0.2 ml/L drinking waterB Ahmadipour et al., 2019
L-arginineAdded to diet at 0.3% overall diet or at 10 g/kgZhang, Beibei, et al., 2018; Khajali et al., 2014
L-carnitine75-150 mg/kgA Geng et al., 2010
Omega-3 fatty acidsBeaufrère, H et al., 2015; Alagawany, M et al., 2019
Turmeric (Curcuma longa) rhizome powder5 g/kg dietD Daneshyar et al., 2012
Vitamin C300-500 mg/kgA Gupta 2011; Beaufrère, H et al., 2015; M Nemati et al., 2017; C Ruiz-Feria
Vitamin E40 to 200 IUC Ruiz-Feria; A Gupta 2011



  • Modify diet to decrease growth rate and restrict feed intake
  • Minimize stress
  • Limit altitude exposure to below 1500m
  • Minimize exposure to excessive heat or cold



Scientific References

Age Range

It most commonly occurs in young, rapidly growing male Cornish breed chickens.

Risk Factors

  • Commercial broiler breeds, such as the Cornish.
  • Males are more susceptible.
  • Living at a high altitude
  • Stress
  • Exposure to cold or hot temperature
  • Hypoxia during incubation
  • Electrolytes supplementation

Also Consider