Malabsorption Syndrome: Introduction
(Runting-stunting syndrome, Pale bird syndrome) |  |
| Malabsorption syndrome is characterized by stunted growth and a lack of skin pigmentation in growing chickens, most commonly meat type or broilers. It has been identified in virtually all countries in which intensive poultry production occurs. |
| Etiology and Transmission: |
| Mycotoxins and several viruses, including enteroviruses, parvoviruses, astroviruses, caliciviruses, arenaviruses, and reoviruses have been implicated. Although the etiology is believed to be complex, only mycotoxins, enteroviruses, and reoviruses have thus far been identified as potential etiologic factors. The specific feedborne mycotoxins involved and concentration needed to induce the syndrome are not well understood. Numerous enteric viruses are prevalent worldwide in
commercially produced poultry. Transmission of viruses occurs via fecal-oral routes. |
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| Clinical Findings: |
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The disease is typically recognized in broiler chicks 1-3 wk old. It is characterized by stunted growth; lack of pigmentation in the skin, feet, or beak; slow feathering; broken or twisted feathers; undigested feed in the feces; and/or poor feed conversion ratios. Diarrhea is common during the initial phases. Severely affected birds do not respond immediately to changes in feed or management practices and are usually culled from flocks before
processing. |
Lesions:
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The severity and type of lesions resulting from both field and laboratory infections vary with the particular agents or combinations of agents involved. Lesions often include enlarged proventriculi, small gizzards, and orange mucus in the small-intestinal lumen. No consistent microscopic lesions are found. Encephalomalacia or rickets may be seen occasionally, presumably as a result of malabsorption or malassimilation of nutrients. |
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| Diagnosis: |
| Clinical signs and lesions permit a presumptive diagnosis, although a similar gross appearance can be caused by a retrovirus (see
reticuloendotheliosis,
Reticuloendotheliosis). More conclusive diagnostic evidence includes finding either viruses in the lesions or dietary toxins. |
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| Prevention and Control: |
| There is no effective treatment for severely affected birds. Sanitation and disinfection will reduce the burden of challenge caused by multiple infectious organisms. There are no vaccines that will prevent malabsorption syndrome. Reovirus vaccines can prevent the stunting and poor feed conversions that occur with pathogenic reovirus infections. Feeds should be analyzed for dietary toxins, and high levels of toxins should not knowingly be fed to commercial poultry. |
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