Introduction

Lesions

Treatment

Immunosuppression

Nutrition

Management

Points to remember

Immunosuppression in poultry has number of adverse effects, be it a breeder, broiler or a commercial layer.  Wing Rot is one of the sequels of such immunosuppression.

Gangrenous dermatitis which is otherwise known as wing rot, blue wing or necrotic dermatitis is a bacterial complication with Clostredia sp., Staphyllococcus sp. and E-coli.  Most of the outbreaks in layers occur in 4-16 weeks and also in rapidly growing broilers, those with poor feathering.

Gangrenous dermatitis (GD) is characterized by areas of necrosis in the skin and underlying tissues, usually resulting in death.  Any damage to the skin followed by secondary bacterial infection with Clostredium septicum, Clostridium perfringens type A, or Staphylococcus aureus alone or in combination, initiates the disease.

Clostridia are part of the normal flora of the chicken gut and are usually found in soil and contaminated litter. Staphylococcal bacteria are everywhere; existing on the chicken's skin, intestine and in the chicken house environment. 

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.  Mortality varies but can be quite high.

• Dark and gangrenous skin with sloughing and feather loss

• Swelling of parenchymatous organs

• Necrosis of liver

• Severe atrophy of bursa

• The subcutaneous tissue with pink or straw colored fluid and gas (emphysema)

Diagnosis is simple as one cannot miss the lesions.  However, there are many similarities between GD and cellulitis.  Both diseases are produced by bacterial infection secondary to skin damage and occur more frequently following immunosuppression.  The primary difference being the type of bacteria causing the infection (E. coli in the case of cellulitis).  Therefore, many of the preventive measures are the same for both diseases.

 Treatment  

Factors influencing GD incidence:

GD can occur in all breed crosses.  Two determining factors that may be associated with the contraction of GD are sex and breed type.  In feather sexable breeds, the slow feathering broiler males may be more vulnerable  to skin injuries due to a longer period of exposure prior to feather coverage than females, which are fast feathering.  Also, male broilers may have a higher frequency of GD because they gain weight faster, are heavier and are more aggressive than females, although the females have more fragile skin.

As stated previously, it is well documented that impaired function of the immune system will contribute to an increase in the incidence of GD.  Many viral agents can affect the immune system, with both CAV and IBDV being particularly harmful.  Significant immunosuppression may occur if birds are exposed to CAV early in life or infected through vertical transmission.  Also, chicks lacking maternal immunity are more susceptible to clinical disease and immunosuppression.  Control of IBDV requires the transfer of sufficient levels of maternal antibody to protect against early field change.  Never ending Mycotoxins menace & stress contribute to immunosuppression.

 Nutrition 
The following nutritional / feed factors impact the incidence of GD because of thier influence on feathering, skin strength and immunocompetence:

1. Protein: Both feathers and skin are composed primarily of protein (keratin). Adequate protein with an appropriate balance of essential amino acids in the ration will promote adequate feather development and increase skin strength.
2. High Energy: High-energy feed (low protein to calorie ration) may marginalize protein intake. Excessive energy in the diets also increases fat deposits in the skin causing increased skin fragility.
3. Vitamin E & Se: A sufficient level of Vitamin E & Se is important for development of the immune system and also protects the bird's cells against oxidative compounds (originated from rancid fat or tissue damage).
4. Fat Rancidity: Use of rancid fat will cause increased utilization of vitamin E (through oxidation) and rapid feed transit (therefore, decreased nutrient uptake). If you are using oils in feed, ensure to blend the feed with good antioxidant.
5. Salt: Insufficient salt in the feed may lead to hysteria and increased cannibalistic behavior.

Management:

Numerous management factors as described below can also influence the occurrence of GD by an increased risk of skin wounds and / or additional bacterial challenge.

1. Stocking Density : High density is directly correlated to increased skin damage

2. Coccidiosis control : Adequate control is important as coccidiosis causes stress, immunosuppression, malabsorption and secondary nutritional deficiencies. Coccidiosis may induce vitamin E deficiency by interfering with absorption and causing increased utilization due to oxidation caused by damage of the intestinal cell walls.

3. Lighting programs: These are important for controlling growth rate and reducing bird activity. Lighting programs can help to reduce excitability, physiological stress and improve immunity.

4. Feed and water outages, loud noises etc. cause the birds to pile or crowd together and must be prevented by adequate management practices. Also ensures sufficient feeder space and avoid harsh feed restriction programs.

5. Heat and humidity: High environmental temperature causes stress and reduces feed consumption (inadequate nutrient intake) which may result in poor feathering and immunosuppression. Excess moisture in the litter promotes bacterial growth. Adequate ventilation and use of nipple drinkers can improve environmental conditions.

6. Farm hygiene: Improved cleaning and disinfecting practices, more frequent litter replacement, water sanitation will decrease the level of bacterial challenge. Litter acidification has been shown to reduce bacterial challenge. Dead birds from GD must be collected minimum of twice per day, otherwise spores produced by clostridia in the carcass will result in heavy environmental contamination.

Antibiotics that have been found effective are pencillin erythromycin, tetracycline, lincomycin, chloram-phenicol etc. Vit E and Selenium are found to be useful in reducing the severity and mortality.
Efforts to prevent GD should be focused on limiting the level of bacterial challenge, boosting immune system function and minimizing the possibility of wounds and / or scratches to the skin through nutrition and management factors.

• Minimize the risk of early exposure to CAV and IBD as much as possible
• Test for seroconversion to CAV before the onset of egg production in all breeder flocks
• Proper vaccination programme against IBDV, MD the immunosuppressive disease.

• Ensure proper protein levels for skin strength and feather development
• Avoid expressive energy levels which increases fat deposits and skin fragility
• Make sure diet has biotin which is important for keratin formation
• Provide Vitamin E and Se in young birds to pep up the immune system
• Test for and prevent fat rancidity which can deplete reserves of vitamin E
• Ensure sufficient salt intake to prevent cannibalistic behavior

• Ensure proper stocking density to prevent skin damage
• Control coccidiosis to prevent stress, malabsorption and secondary nutritional deficiencies
• Implement a lighting program to help control growth rate and activity to promote immunity
• Avoid feed and water outages, loud noises and bird migration which cause crowding
• Ensure adequate ventilation to minimize heat and humidity
• Maintain good farm hygiene and treat litter as needed. Remove daily mortality as quickly and as often as possible