Gangrenous dermatitis (GD) is a disease that affects poultry (layers, chickens, and turkeys) caused by Clostridia and Staphylococcus aureus, either alone or in combination. It is an opportunistic disease and its presence indicates that something is not going well in the farm. It received different names, such as necrotic dermatitis and gangrenous cellulitis, but gangrenous dermatitis is the most used.

Importance of gangrenous dermatitis in the United States

Although it has been considered a sporadic disease, its prevalence and severity has increased over the past two decades in the US and in other parts of the world. This is because of several factors, which include the limitation of the use of antibiotics: lower control of the bacteria in the farms leads to a higher presence of these opportunistic microorganisms. The reduction of the use of chemicals against coccidiosis and necrotic enteritis, two diseases tightly related to GD, lead to an increase of prevalence, too.

According to the President of the American Veterinarians in Broiler Production in 2018, gangrenous dermatitis is one of the major disease issues for broiler production. It is also one of the most important diseases in commercial turkeys in the US (USDA-APHIS). The costs of this disease are related to the associated mortality and the increased condemnation rates and low-quality carcasses of affected birds at slaughter.

Etiology: opportunistic microorganisms

The causative agents are Clostridium septicum, C. perfringens type A, and Staphylococcus aureus. They are often found in the farm environment and the intestine and skin of the birds. Their presence at low concentrations, though, does not always correlate with a challenge, because they are opportunistic pathogens. The incidence and severity will depend on the bacterial strains involved and their capacity to produce toxins, and the type toxins produced.

They are very resistant to unfavourable environmental conditions such as desiccation, heat and cold, and to disinfectants.

Predisposing factors are key to start an outbreak

In opportunistic diseases such as GD, predisposing factors are of major importance to prevent it. In this case, there are multiple factors that are closely related to the disease:

• Presence of diseases and/or conditions that produce immunosuppression (infectious bursal disease, reovirus, infectious bronchitis, stress…)
• Poor litter condition. Any factor causing diarrhoea or environmental conditions that increase litter moisture will lead to an increase of the prevalence of the causative bacteria in the environment and the intestines.
• Management practices and rearing conditions that promote scratching (overcrowding, feed outage, time for feeding, stress…). Many times, the disease starts as a wound to the skin that is secondarily contaminated with bacteria.
• A high charge of microbes in the environment, particularly if dead birds remain in the facilities for too long.

Main signs and lesions of the disease

It commonly affects birds that are close to market age (more than 35 days for broilers, more than 13 weeks for turkeys). It causes necrosis of the skin and acute mortality. The necrosis can also affect the subcutaneous tissue and, sometimes, the muscle.

First, birds show small pimples on the skin, that turn to spots in the wings, breast, abdomen, and thighs. These lesions are easily observed on top of the wings when walking between birds and appear together with rapidly increasing mortality, from a few birds to 3% in a few days. Strong immunocompetent birds will not be affected.

Dead birds are decomposed faster than usual because of the high presence of bacteria, and they are filled with gas, which changes the consistency of the tissues.

Prevention: a multifactorial approach

Prevention should have three main approaches: reduction of the presence of bacteria,  immunosuppression prevention, and decrease the prevalence of skin lesions. Biovet S.A. has developed natural solutions that, together, help to prevent gangrenous dermatitis.

Alquermold Natural to reduce the challenge in the environment and the digestive tract

It is important to use an effective bactericide against Clostridia and Staphylococcus because lower bacterial counts in the intestine and the litter will decrease the challenge that birds are exposed to.

Alquermold Natural is a product with strong bactericidal and fungicidal activities. Its addition to feed or water decreases the loads of Clostridia in the digestive tract and has a residual effect in the excrement and litter.

The mechanism of action is based on the synergy of the cimenol ring, plant-based aromatic compound, and the citric acid. They act together to destroy the cell membrane of pathogenic bacteria and cause their death. It is innocuous for the beneficial flora and does not create resistances.

Alquernat Immuplus to naturally boost immunity

Alquernat Immuplus is a plant-based product that, especially in stressful situations, prevents immunosuppression. It contains immunobooster pronutrients, active molecules from plant extracts, that stimulate the immune cells through increasing the expression of specific genes of the cellular DNA.

When birds receive pronutrients, whether in the feed or in drinking water, the immune system is ready to fight any immunosuppressive agent and to prevent the development of GD. In addition, if pronutrients are administered during vaccination, they increase antibody production and, therefore, animal protection against diseases such as Gumboro disease (+8.17%), infectious bronchitis (+23.48%), and Newcastle disease (+6.23%), among others.

AVAL 9 to improve skin integrity

Integrity of the skin and digestive mucosa is key to control gangrenous dermatitis as it reduces the probability of opportunistic microorganism to enter the organism or deeper skin layers.

Biovet’s R&D Department designed a product that target the integrity of the tissues: AVAL 9. It supplies biotin, an essential vitamin for the skin and other epithelia that is very often found in low quantities in commercial diets, due to cereal quality and its high price as a specific additive. With AVAL 9, animals receive the necessary biotin for the correct status of the skin and digestive tract, and they are more resistant to skin lesions and enteric infections.

In conclusion: three natural solutions to achieve protection against gangrenous dermatitis

Gangrenous dermatitis is a serious concern for many broiler operations. Many predisposing factors lead to the development of this disease, which causes high mortality and carcass condemnation rates.

There is no unique solution to prevent it because it is a multifactorial disease. Despite this, Biovet S.A. has developed natural solutions that, together, reduce the risk of gangrenous dermatitis: Alquernat Immuplus to boost immunity, Alquermold Natural to reduce the challenge in the farm, and AVAL 9 to improve skin integrity.

The combination of these three natural solutions helps the producers to achieve better performance results and decreases the prevalence of GD. They are products based on natural substances that do not create resistances and do not need withdrawal period.