From the AAAP Avian Disease Manual:
[FONT=TimesNewRoman,Bold][FONT=TimesNewRoman,Bold]GANGRENOUS DERMATITIS[/FONT][/FONT]
(Necrotic Dermatitis)
DEFINITION
Gangrenous dermatitis is a disease of young growing chickens characterized by necrotic areas of the skin
and by a severe, underlying, infectious cellulitis.
OCCURRENCE
Most outbreaks have occurred in chickens 4-16 weeks old. Young birds of this age group may be poorly
feathered. Outbreaks often occur in excessively warm, humid houses.
HISTORICAL INFORMATION
Gangrenous dermatitis was reported first in 1930 although most outbreaks have been reported since 1963.
Some of the more recent reports have suggested that affected flocks may be immunologically deficient.
ETIOLOGY
It appears that primary skin lesions are secondarily invaded by various bacteria including
[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]Clostridia sp[/FONT][/FONT].
(especially
[FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]C. septicum[/FONT][/FONT]), [FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]Staphylococcus [/FONT][/FONT]sp. and [FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]Escherichia coli[/FONT][/FONT].
EPIZOOTIOLOGY
1. Cutaneous wounds probably occur initially as a result of cannibalism, mechanical trauma (from mechanical
feeders, etc.), or other trauma. Bacteria invade the traumatized skin and underlying tissue and their toxins
or metabolites cause cellulitis. Septicemia and toxemia follow, leading to death.
2. Increased susceptibility of affected flocks to infection is an important factor in the pathogenesis. This
increased susceptibility is commonly related to immunosuppression secondary to infectious bursal disease
or chicken infectious anemia virus.
3. Other factors that may enhance susceptibility include aflatoxicosis, nutritional insufficiency or imbalance,
or poor sanitation.
CLINICAL SIGNS
A sudden, sharp increase in mortality is often the first indication of onset. When sick birds are observed,
they are depressed, and sometimes prostrate or lame. Skin lesions, often crepitant, are apparent in live or dead
birds. The course of the illness is often less than 24 hours. Mortality varies but can be quite high.
LESIONS
1. There are scattered patches of darkened, gangrenous skin, often with cutaneous sloughing or feather loss in
affected areas. Marked emphysematous or serosanguineous cellulitis underlies some skin lesions,
especially with clostridial infections.
2. Swelling and infarction may be apparent in parenchymatous organs. There may be foci of necrosis in the
liver.
3. Severe atrophy of the bursa of Fabricius is usually present.
[FONT=TimesNewRoman,Bold][FONT=TimesNewRoman,Bold]GANGRENOUS DERMATITIS[/FONT][/FONT]
DIAGNOSIS
A tentative diagnosis often can be made on the basis of history and gross lesions. For confirmation, smears
or histologic sections of affected tissues will reveal bacteria. Bacteria can be cultured from the area of cellulitis.
CONTROL
1. The cause of skin trauma should be found and eliminated. If cannibalism is a cause, it may be necessary to
trim the beaks or improve the quality of previous beak trimming. Mechanical feeders should be examined
carefully as a source of possible trauma.
2. Vaccinate the breeder flock for infectious bursal disease to prevent or reduce possible immunosuppression
in the progeny.
3. Insofar as is possible, eliminate all stresses on the birds (e.g., parasitism, malnutrition, coccidiosis, etc.).
4. Improve sanitation in the house, particularly that of the feeders, waterers, and litter. A thorough cleaning
and disinfection of the house may be helpful. If litter in the house stays wet, improve moisture control.
Repeat problem houses may benefit from salting the floor at cleanout. Cheap grade feed salt is used on the
soil at a rate of 60-63 lb/1,000 ft
2.
5. Broad-spectrum antibiotics (e.g., penicillin, erythromycin, and tetracyclines) can be added to the ration of
the flock and will reduce mortality.
TREATMENT
In addition to adding broad-spectrum antibiotics to the ration, valuable birds can be treated individually
with penicillin, tetracyclines, or other fast-acting antibiotics.
