Gangrenous dermatitis in poultry

Gangrenous dermatitis is characterized by areas of death and putrefaction in the skin and underlying

tissues, including muscle. It is quite a common disease. Also known as "wing rot", gangrenous

dermatitis is a serious disease and usually results in death. It is mainly a disease of the broiler

over 4 weeks of age, but is also quite common in grower between 16 and 19 weeks of age. Its occurrence is more common in warm, humid conditions. Mortality ranges from I to 60%.

Causes

I. Bacteria known as clostridia, staphylococci, and E. coli, either singly or in combination, are involved. Combined infections are more severe.

2. Gangrenous dermatitis is more likely to occur in the presence of those diseases which produce

immunosuppression, such as Gumboro disease. Immunosuppression is suppression of the natural immune responses that produce immunity.

3. Other predisposing factors are unhygienic management (poor sanitation), overcrowding, mycotoxins, infectious anaemia virus, and reovirus.

Development of the Disease

I. Most cases in broilers occur between 4 and 6 weeks and in layers between 6 and 20 weeks.

2. Clostridial organisms are present in soil, faeces, dust, contaminated litter or feed, and in the intestinal contents (mainly caeca) of healthy birds. Staphylococci exist everywhere and are common inhabitant

of skin and linings of the digestive, respiratory, and urinary tracts.

3. In many cases, gangrenous dermatitis follows diseases caused by other infectious agents, such as Gumboro virus, chicken infectious anaemia virus, reticuloendotheliosis virus, and avian adenovirus infections, including inclusion body hepatitis.

4. Gangrenous dermatitis usually occurs secondarily following skin injury. This is because all the

infectious agents mentioned above produce immunosuppression, and a damaged immune system is the underlying predisposing factor that allows gangrenous dermatitis to develop.

Symptoms

I. There is increased mortality in the flock. Affected birds are depressed, show loss of appetite, leg weakness,

incoordination of movements, and die within a few hours.

2. The period of illness is very short, usually less than 24 hours. Mortality ranges from I to 60%.

Postmortem Findings

I. The skin and underlying tissues under the wings, between the thighs, and over the ribs and flanks (i.e., area

between ribs and hips) of the birds are very dark, moist, usually devoid of feathers, foul-smelling, and show putrefaction .

2. Deep red and swollen areas are found on the feet, legs, and sometimes around the feather follicles of the wings . There is a blood-tinged watery fluid under the skin.

3. The surrounding muscle is usually coloured and contains fluid (oedematous). If clostridial organisms are involved, gas is produced in the muscle.

Diagnosis

The postmortem picture is diagnostic.

Treatment

I . No treatment has proved completely successful. This is because of the nature of tissue changes. Dead tissue cannot be treated. Moreover, many kinds of causes are involved in the production of disease.
2. However, penicillins, tetracycline, chlortetracycline, oxytetracycline, erythromycin, or bacitracin may be given in the drinking water.
3. Gentamicin injections have proved helpful in controlling the disease. But this antibiotic could be very damaging to the kidneys.
4. Follow up should be done by the addition of antibiotics in the feed.
5. Water acidification, with citric and propionic acid, has been used to reduce but not eliminate mortality in flocks.
6. Control of symptoms and lesions has also been achieved by using water acidifiers and acidification of litter.

Control

I . Avoid overcrowding to prevent skin damage.
2. Maintain good standards of hygiene in management. Improve litter condition, reduce moisture and bacterial levels in the environment, and minimize trauma (injury) to the bird.
3. Protect the birds against immunosuppressive diseases, like Gumboro disease and others, by carrying out proper and timely vaccinations.
4. Remove dead birds daily as quickly and as often as possible.
S. House sanitation should be carefully controlled. Feed, water, and litter management are very important.
6. Good nutrit ion and management of stress are also helpful.