Footpad dermatitis: what is it?

Footpad dermatitis or contact dermatitis is a type of dermatitis that is common in poultry, particularly in broiler chickens and turkeys, characterized by the presence of lesions in the footpad. It is an inflammation of the cutaneous tissue that can affect from superficial to deeper skin layers, depending on the severity of the lesions.

Why is it important?

The importance of assessing the prevalence, extension and severity of these lesions is because they are related to other underlaying problems in the farm and, additionally, they work as an animal welfare indicator. Footpad dermatitis also has a direct effect on locomotion, which has an impact on water and feed intake.

The causes of footpad dermatitis can be classified into three groups, depending on whether they are pathological, management-related or nutritional. When there is a high prevalence of footpad dermatitis, the possible causes need to be evaluated to apply corrections, because the affected animals are suffering and have a limited access to feed and water, which in turn affects productivity. Moreover, footpad lesions are a gate for pathogens such as Staphylococcus or E. coli, which can aggravate the injury and cause local or systemic infections.

Regarding footpad dermatitis as an indicator of animal welfare, the severity and intensity are evaluated in the European Union and, when more serious issues are detected, legal measures are taken, such as fines or other sanctions [1]–[3].

Another thing to consider is that, in the Asian market, chicken feet are for human consumption, so that the quality of the product depends on the absence of lesions and is an essential requirement for exportation.

Evaluation methods

There are several scoring systems, based on different lesion degrees, to evaluate the incidence and severity of footpad dermatitis.

The Swedish scoring system, based in three lesion degrees, is used in Europe due to it is reliable to evaluate the status of animal flocks at slaughterhouses; so that, when a flock is above the permitted levels, sanctions are applied. Other systems, such as the one proposed by Hocking (2008) [4] to evaluate footpad lesions in turkeys, consist of five different degrees.

Table 1. Source: Management Tools to Reduce Footpad Dermatitis in Broilers (Aviagen, 2012)[5].

Table 2. Source: Standard European footpad dermatitis scoring system for use in turkey processing plants (Hocking, 2008) [4].

Microscopically, in animals with mild lesions, all the epidermal layers are affected: there is hyperplasia of the stratum spinosum and cells that invade the basal layer with centric and small nuclei. In birds with necrotic lesions, it is not possible to identify, microscopically, the different layers of the epidermis and the dermis is also affected in birds with necrotic lesions.

Image 2. Skin layers, where (1) is the epidermis, (2) is the dermis and (3) is the subcutaneous tissue.

What causes footpad dermatitis in poultry?

Footpad dermatitis is an issue with multiple causes, which can be classified into three main groups: pathological, management-related and nutritional. These are defined in the following sections.

• Pathological causes

Any pathological cause that causes gastrointestinal problems, whether from toxic or infectious origin, gives rise to an increased prevalence of footpad dermatitis. This is because they decrease feces consistency, which, in turn, decreases litter quality.

The most frequent infectious agents that cause digestive symptoms in broiler chickens are bacteria (E. coli, Clostridium) and protozoa (coccidia). These microorganisms infect and destroy the enterocytes, with the consequent loss of epithelial tissue and irritation of the gut mucosa, leading to poor feed digestion and absorption, rapid transit and wet feces, which increase litter moisture.

Mycotoxins, especially trichothecenes, are the toxins that usually affect birds’ gut health. They cause necrosis by contact and damage the peak, gizzard and intestinal villi. Their distinctive lesions are a result of cell death in the upper part of the villi. Pasty, orangish feces from affected animals negatively impact litter quality.

• Management-related causes

Any management practice that negatively affects litter quality will increase predisposition to suffer from footpad dermatitis.

The litter

• Material: absorbent materials are recommended, such as wood shavings [6], [7].
• Quality: the litter should stay dry and aired, although materials that are too dry and dull can damage the chicks’ footpads, and lesions may evolve to footpad dermatitis.
• Thickness: thinner litters allow better aeration and decrease leg and footpad problems. Despite this, if the floor is cold, thin litters will negatively impact on growth. For this reason, if the floor is poorly isolated and/or cannot be pre-heated, thicker litters are recommended.

Light program

The light program should be adjusted to the recommendations of each species. Light intensity, color and distribution should be considered [9].

Light influences birds’ behavior, in fact, some studies show that programs with intermittent light stimulate bird activity during the light phases, strengthen their legs and decrease the prevalence of footpad dermatitis. Moreover, active birds scratch the litter and increase aeration.

Temperature and ventilation

Temperature and ventilation should be adjusted to maintain relative humidity among the recommended values. On one hand, it should be below 70% to avoid decreasing the litter quality. On the other hand, if it goes below 50%, it can cause problems due to an excessive dryness of the litter material, which can damage the footpads.

The most recommendable heating systems are the ones that produce less humidity and insufflate hot air on the litter, to help it stay dry. If temperature goes below the condensation point, water from air will condensate on surfaces, including the litter, which get wet and cause an increase in footpad problems.

Population density

Farms with high population densities need more complex management practices and, therefore, it is more likely to have litter problems and a higher incidence of footpad dermatitis [11]. This is because density has an impact on relative humidity, especially if ventilation is poor. In addition, at higher densities, there are more feces in the litter and birds’ activity is limited [12].

Therefore, farms with high densities need to consider management factors in a much more serious way in order to avoid footpad dermatitis to become a major issue.

• Nutritional causes

Nutrition is a very important factor to consider, since it affects water intake, feces consistency and, therefore, the litter quality.

Feed formulation

Follow the nutritional specifications given by the line producers or from trusted sources only. The main parameters to consider related to litter quality are:

Feed presentation

Avoid feed in flour presentation, especially in small particles that produce dust, since it decreases productive performance, increase water consumption and may cause rapid digestive transit.

Water

Water quality and the number and type of drinkers should be adjusted to the birds’ needs, to ensure an adequate water intake and avoid leakage.

• Avoid the presence of bacteria ( coli, Pseudomonas) that cause enteritis and, therefore, poor litter quality.
• Nipple drinkers with a cup are the ones with less leakage.
• Periodically verify that there are no leakages or obturations in the system.
• Adjust the drinkers’ height and water pressure according to the manufacturer’s instructions and the age of the animals.

Prevention of footpad dermatitis

Prevention of footpad dermatitis in broiler chickens and turkeys is based on maintaining a dry and high-quality litter, which consists in controlling the mentioned factors. Hence, prevention measures are based on:

The prevention of infections and mycotoxicoses

• Use preservatives of long-term and broad-spectrum efficacy in feed for the control of microbiological contaminations. Preservatives based on the cimenol ring are highly recommended, since their efficacy lasts in the gut to promote the balance of the digestive flora and prevent alterations of the feces consistency.
• Use intestinal optimizer pronutrients, natural molecules, to control coccidiosis, a disease that significantly alters litter quality. Pronutrients have several advantages compared to other prevention methods, such as they do not require a withdrawal period nor create resistances.
• Use mycotoxin binders in the feed. Molecules like the Silicoglycidol bind mycotoxins and avoid their negative effects, whether in the digestive tract or in the organism, as they prevent mycotoxin absorption.

The implementation of good management practices

• Cleaning, disinfection and drying the facilities before the entrance of the birds is essential. Changing the litter for each production batch is highly recommended, as well as to use an absorbent material.
• The light program should follow the recommendations for the species and age of the animals, and preferably stimulate birds’ activity.
• Perform maintenance to the ventilation, heating and refrigeration systems so that the farm is in optimal conditions of temperature and relative humidity. It is also important to continuously evaluate these parameters.
• Perform maintenance to the drinkers to keep them clean and in good conditions, to avoid leakage. Microorganisms should also be eliminated from the water (sanitization).
• The population density should be adjusted not only to the local regulations, but to the management practices and the facilities.

Adjust the nutritional parameters to the birds’ requirements

• Diet formulation should match the requirements of the species and age. Pay attention to the ingredients that can cause an increase of water consumption or rapid transit, such as the levels of protein, sodium and potassium and the concentration and quality of fats.
• Deficiencies of components related to the integrity of the epithelia should be avoided, such as biotin deficiency. For this, we recommend increasing by 10% the recommended biotin level in the diet. The addition of products that contain this compound is another option, as they help to prevent footpad dermatitis.
• The addition of enzymes depending on the composition of the diet is an essential thing to consider, since some raw materials contain carbohydrates that birds cannot digest. Usually, diets contain high protein levels, for which it is ideal to add subtilisin. In addition, avoid ingredients that contain antinutritional factors, or add the enzymes necessary to inactivate them.

Other additives to control footpad dermatitis

• Intestinal conditioner pronutrients, when added to the diet or in the drinking water, improve the integrity of the digestive epithelium and, therefore, improve digestion and nutrient absorption, which has a positive impact on feces consistency and litter quality. Several field trials, one of them summarized below, show the efficacy of these pronutrients to prevent footpad dermatitis and improve animal welfare.

Conclusions

The presence of footpad dermatitis in a farm is an indicator of a subjacent problem. For this, it is important to evaluate the its incidence and apply changes to reduce it.

It is a multifactorial dermatitis that may be caused by microbiological, management-related or nutritional factors, or a combination of these.

Prevention is based on keeping litter under optimal conditions by using the tools to maintain intestinal health, good environmental conditions and appropriate management practices.

Bibliography

[1] European Commission. Directorate-General for Health and Food Safety. Food and Veterinary Office., Use of slaughterhouse data to monitor welfare of broilers on farm overview report. Publications Office, 2016.
[2] S. S. e I. Gobierno de España (Minisrerio de Sanidad and aecosan, “Procedimiento para la detección post-morten de insuficiente bienestar animal en explotaciones de pollos de engorde y actuaciones de la autoridad competente,” 2014.
[3] Council Directive 2007/43/EC, “Laying down minimum rules for the protection of chickens kept for meat production (Text with EEA relevance),” 2007.
[4] P. M. Hocking, R. K. Mayne, R. W. Else, N. A. French, and J. Gatcliffe, “Standard European footpad dermatitis scoring system for use in turkey processing plants,” World’s Poultry Science Journal, vol. 64, no. 3, pp. 323–328, Sep. 2008, doi: 10.1017/S0043933908000068.
[5] I. de Jong and I. Jan van Harn, “Management Tools to Reduce Footpad Dermatitis in Broilers,” 2012.
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[7] R. K. Mayne, “A review of the aetiology and possible causative factors of foot pad dermatitis in growing turkeys and broilers,” World’s Poultry Science Journal, vol. 61, no. 2, pp. 256–267, Jun. 2005, doi: 10.1079/wps200458.
[8] C. Ekstrand, B. Algers, and J. Svedberg, “Rearing conditions and foot-pad dermatitis in Swedish broiler chickens,” 1997.
[9] D. Díez, “El fotoperiodo en broilers y los programas de iluminación,” Veterinaria Digital, 2019.
[10] W. D. Weaver and R. Mejjerhof, “The Effect of Different Levels of Relative Humidity and Air Movement on Litter Conditions, Ammonia Levels, Growth, and Carcass Quality for Broiler Chickens,” Beekbergen and Blacksburg, The Netherlands, Jun. 1990. [Online]. Available: http://ps.oxfordjournals.org/.
[11] C. H. McMurray, “A contact dermatitis of broilers – epidemiological findings,” Avian Pathology, vol. 16, no. 1, pp. 93–105, Jan. 1987, doi: 10.1080/03079458708436355.
[12] C. C. Berg, Foot-pad dermatitis in broilers and turkeys : prevalence, risk factors and prevention. Swedish University of Agricultural Sciences, 1998.