The incidence of ectopic cartilaginous and osseous lung nodules in young broiler fowls with ascites and various other diseases

Maxwell, M.H.; Anderson, Iain A.; Dick, Laura

doi:10.1080/03079458808436466

Cited by 12 publications

(8 citation statements)

References 7 publications

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“…The sudden decrease in the incidence of lung nodules in the experimental birds at week 8 is difficult to explain. In previous studies (Maxwell, 1988a;Maxwell et al, 1988) there were some birds with a very low incidence of lung nodule involvement, despite the presence or absence of ascites. Thus, there are clearly some birds, as in the present study, with relatively small nodule counts that will be unaffected by the experimental condition.…”

Section: Discussionmentioning

confidence: 99%

“…It was postulated that this may have been influenced by the environment, possibly due to poor ventilation. A companion study demonstrated that broilers with different diseases had more nodules in their lungs than control birds (Maxwell et al, 1988). Birds with an ascitic syndrome had significantly more nodules than other groups of diseased birds, with a greater number occurring in the left lung than in the right.…”

Section: Introductionmentioning

confidence: 99%

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Ectopic cartilaginous and osseous lung nodules induced in the young broiler by inadequate ventilation

et al. 1989

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ectopic cartilaginous and osseous lung nodules induced in the young broiler by inadequate ventilation

et al. 1989

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“…Increased numbers of cartilaginous and bony masses have been reported in the lungs of broilers with ascites (Maxwell, 1988;Maxwell et al, 1988;Julian et al, 1989a;Reece, 1991;Wilson et al, 1988). Large numbers of these nodules could obstruct blood-flow but there is no evidence that the increased number are the cause of PHS (Julian, 1990b).…”

Section: Reduced Vascular Capacitymentioning

confidence: 97%

Ascites in poultry

1993

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SUMMARYResearch on ascites occurring in meat-type chickens reared at moderate and low altitude has shown that the pathogenesis is similar to that of the high altitude disease. Pulmonary hypertension (PH) caused by increased blood flow or increased resistance to flow in the lung results in right ventricular hypertrophy (RVH), valvular insufficiency, increased venous pressure and ascites. The structure of the avian heart, with its thin-walled right ventricle and muscular right atrioventricular valve, allows PH to induce heart failure quickly. The sudden increase in pulmonary hypertension syndrome (PHS) in meat-type chickens in the 1980s was associated with a rapid increase in growth rate and feed conversion. This was a result of a combination of genetic selection for fast-growing, heavy broilers with low feed conversion and a more dense, high caloric, pelleted food that supplied all the nutrients required for rapid growth and encouraged a high nutrient intake. PHS in meat-type chickens is usually primary pulmonary hypertension, that is, PH that occurs without evidence of prior heart or lung disease that could account for the increase in blood flow or resistance to flow that results in the increased pressure in the pulmonary arteries. The lungs of birds are firm and fixed in the thoracic cavity and they do not expand to draw air into the lung. The blood and air capillaries form a rigid network that allows only minimal expansion of the blood capillaries when more blood flow is required. Air is moved through the lung by abdominal movement which draws air in and out of the air sacs. The anatomy and physiology of the avian respiratory system are important in the susceptibility of meat-type chickens to PHS. The small stature of the modern meat-type chicken, the large, heavy breast mass, the pressure from abdominal contents on air sacs, and the small lung volume compared to body weight, may all be involved in the increased incidence of PHS. There is limited space for blood flow in the avian lung. Factors that increase blood flow or increase resistance to flow are additive. Increased blood viscosity caused by the polycythaemia of hypoxia, or increased erythrocyte rigidity of high Na + , are more likely to produce PH in fast-growing than in slow-growing birds. Increased flow due to cold exposure is also additive. Ascites caused by PH is a production-related disease at low altitude. It can be prevented easily by restricting growth rate. It is possible that some meat-type chickens of the phenotype we have created have reached the limit of blood flow through their lungs and that future improvements in growth rate will only be possible if the lung and abdominal cavity capacities are enlarged.

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“…Although these nodules have been well characterized, their origin and significance have not been fully explained (Borst et al, 1976;Julian, 1983Julian, , 1989Sarango & Riddell, 1985;Wight & Duff, 1985;Carpenter et al, 1986;Maxwell et al, 1988). Maxwell et al (1986) first described the presence of hyaline-cartilaginous nodules in birds suffering from BPHS.…”

Section: Introductionmentioning

confidence: 99%

Morphometric and histologic changes in the pulmonary system of broilers raised at simulated high altitude

et al. 1995

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SUMMARYBroilers were reared in conditions of hypobaric hypoxia (3500 m altitude) to investigate the development of pulmonary nodules in birds reared in hypobaric hypoxia and judged by clinical observation to be developing broiler pulmonary hypertension syndrome (BPHS); in unaffected birds reared in hypobaric hypoxia; and in birds reared at ambient atmospheric pressure. Gross pulmonary morphometric measurements, packed cell volume, electrocardiogram QRS amplitude and body weight also were compared among the three experimental groups. Results indicate that hypobaric hypoxia alone exercised little influence on the development of pulmonary nodules. Nodule numbers per section and nodule area per section were numerically greater in birds reared in hypobaric hypoxia, but there were no consistent significant differences in nodule numbers in birds which developed BPHS. As expected, absolute lung length, inter-rib distance and lung volume increased significantly with increasing age and size; but when these parameters were expressed as a function of body weight, they decreased with increasing age. Again, intergroup differences were inconsistent. Packed cell volume and electrocardiogram QRS amplitude were significantly increased in birds reared in hypobaric hypoxia.

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The incidence of ectopic cartilaginous and osseous lung nodules in young broiler fowls with ascites and various other diseases

Cited by 12 publications

References 7 publications

Ectopic cartilaginous and osseous lung nodules induced in the young broiler by inadequate ventilation

Ectopic cartilaginous and osseous lung nodules induced in the young broiler by inadequate ventilation

Ascites in poultry

Morphometric and histologic changes in the pulmonary system of broilers raised at simulated high altitude

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