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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.

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.

Diagnosis

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

Cyanosis

Lethargy

Diagnosis

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

Treatment

Name	Summary
Supportive care	Isolate 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.
Enalapril	30-60 ppm	M Fathi et al., 2015
Furosemide	0.5-1 mg/kg	Beaufrère, H et al., 2015
Imidapril	3 mg/kg once daily	X Hau et al., 2014.
CoQ10	20-40 mg/kg	A Geng et al., 2010; M Nemati et al., 2017
Elecampane (Inula helenium) rhizome	500-2000 mg/kg diet	M Abolfathi et al., 2020
Garlic (Allium sativum) bulb extract	5 g/kg diet	S Varmaghany et al., 2015
Hawthorn (Crataegus oxyacantha) extract	0.1-0.2 ml/L drinking water	B Ahmadipour et al., 2019
L-arginine	Added to diet at 0.3% overall diet or at 10 g/kg	Zhang, Beibei, et al., 2018; Khajali et al., 2014
L-carnitine	75-150 mg/kg	A Geng et al., 2010
Omega-3 fatty acids	Beaufrère, H et al., 2015; Alagawany, M et al., 2019
Turmeric (Curcuma longa) rhizome powder	5 g/kg diet	D Daneshyar et al., 2012
Vitamin C	300-500 mg/kg	A Gupta 2011; Beaufrère, H et al., 2015; M Nemati et al., 2017; C Ruiz-Feria
Vitamin E	40 to 200 IU	C Ruiz-Feria; A Gupta 2011