The pathology of the avian integument: A review

The evolutionary origin of avian facial bristles and the likely role of rictal bristles in feeding ecology

Facial bristles are one of the least described feather types and have not yet been systematically studied across phylogenetically diverse avian species. Consequently, little is known about their form, function and evolutionary history. Here we address this knowledge gap by characterising the evolution of facial bristles for the first time. We especially focus on rictal bristle presence and their associations with foraging behaviour, diet and habitat preferences in 1022 avian species, representing 91 families in 29 orders. Results reveal that upper rictal, lower rictal and interramal bristles were likely to be present in the most recent common ancestor of this avian phylogeny, whereas narial bristles were likely to be absent. Rictal bristle presence, length and shape varied both within and between avian orders, families and genera. Rictal bristles were gained or lost multiple times throughout evolution, which suggest that the different morphologies observed within species might not be homologous. Phylogenetic relatedness is also not likely to be the only driver of rictal bristle presence and morphology. Rictal bristle presence and length were associated with species-specific ecological traits, especially nocturnality. Our findings suggest that species foraging in low-light conditions are likely to have longer rictal bristles, and that rictal bristles are likely to have evolved in early birds.

Establishment of a culture model for the prolonged maintenance of chicken feather follicles structure in vitro

Protocols allowing the in vitro culture of human hair follicles in a serum free-medium up to 9 days were developed 30 years ago. By using similar protocols, we achieved the prolonged maintenance in vitro of juvenile feather follicles (FF) microdissected from young chickens. Histology showed a preservation of the FF up to 7 days as well as feather morphology compatible with growth and/or differentiation. The integrity of the FF wall epithelium was confirmed by transmission electron microscopy at Day 5 and 7 of culture. A slight elongation of the feathers was detected up to 5 days for 75% of the examined feathers. By immunochemistry, we demonstrated the maintenance of expression and localization of two structural proteins: scaffoldin and fibronectin. Gene expression (assessed by qRT-PCR) of NCAM, LCAM, Wnt6, Notch1, and BMP4 was not altered. In contrast, Shh and HBS1 expression collapsed, DKK3 increased, and KRT14 transiently increased upon cultivation. This indicates that cultivation modifies the mRNA expression of a few genes, possibly due to reduced growth or cell differentiation in the feather, notably in the barb ridges. In conclusion, we have developed the first method that allows the culture and maintenance of chicken FF in vitro that preserves the structure and biology of the FF close to its in vivo state, despite transcriptional modifications of a few genes involved in feather development. This new culture model may serve to study feather interactions with pathogens or toxics and constitutes a way to reduce animal experimentation.

Occurrence and relevance of Mycoplasma spp. in free-ranging pheasants from northwestern Germany

Since 2008/2009, the population of free-ranging ring-necked pheasants was recorded to decrease all over Germany. Various Mycoplasma (M.) spp. are causing severe respiratory signs in captive game bird species. Furthermore, M. gallisepticum is responsible for massive die-offs in consequence to severe conjunctivitis in house finches in the USA. Therefore, the prevalence of mycoplasmas in free-ranging pheasants was investigated and a potential impact on the population decline of pheasants discussed. Within this study, 150 free-ranging pheasants were sampled via tracheal swabs and tissue samples of the trachea and the periorbital skin, as the latter displayed inflammatory alterations in previous studies. In total, 177 samples were investigated for the presence of mycoplasmas using cultural and molecular biological methods. In 76 birds, necropsy was performed additionally. In total, 73.7% (51/76) of the examined pheasants had periorbital skin alterations. Furthermore, 64.4% (114/177) of the samples tested positive for mycoplasmas via PCR. Overall, 102/177 samples (57.6%, 78/105 tracheal swabs, 19/51 skin tissue, 5/21 trachea tissue) tested positive for mycoplasmas via culture. Mycoplasma gallinaceum (n = 50), M. pullorum (n = 45), M. glycophilum (n = 43), M. iners (n = 11), and M. gallinarum (n = 5) were frequently isolated. In 45 cases (45.9%), multiple Mycoplasma spp. were isolated from one sample. All examined samples tested negative for M. gallisepticum. Of 51 skin samples investigated for mycoplasmas, 24 (47.1%) showed inflammatory skin alterations in histology, and 58.3% (14/24) of these samples tested positive for Mycoplasma spp. additionally. Overall, there was a significant correlation between inflammatory altered skin samples and the detection of mycoplasmas in periorbital skin samples. Based on the present results, the isolated Mycoplasma spp. may play a role as facultative agents for the observed inflammatory skin alterations. However, additional investigation is needed to confirm this presumption.

Atypical Manifestation of Cutaneous Fowlpox in Broiler Chickens Associated with High Condemnation at a Processing Plant

The present case is an unusual report of cutaneous fowlpox with an atypical appearance and incidence in broilers. Gross skin lesions were noticed in 41-day-old commercial broilers during the veterinary inspection at a processing plant in the north of Iran. The skin lesions were only observed on feathered skin areas of the broilers and remained unnoticed until slaughter. Round, nodular or coalescent, elongated, reddish-brown proliferative lesions were mainly located on the back, thighs, and proximal areas of the neck of broilers. Nonfeathered skin, including the wattle, comb, eyelids, and legs, were not affected. This condition incurred high losses due to a 5.3% condemnation and trimming of carcasses. Cutaneous lesions were sampled for histopathology and molecular virology for further investigations. Histopathology revealed multifocal necrotic dermatitis with epidermal eosinophilic cytoplasmic inclusion bodies in the skin lesions. Molecular investigations confirmed the presence of fowlpox virus (FWPV) in the proliferative lesions, with further investigations identifying two FWPV genome populations, one carrying a portion of the reticuloendotheliosis virus (REV) and the other a nearly complete REV provirus. Furthermore, the 4b core protein gene-based molecular analysis clustered the field virus into clade A of the genus Avipoxvirus.

Zinc oxide nanoparticles prevent multidrug resistant Staphylococcus-induced footpad dermatitis in broilers

The current experiment was designed to evaluate the effects of dietary supplementations of zinc oxide nanoparticles (ZONPs) on some behavioural, performance, welfare and histopathological changes in broilers exposed to multidrug resistant Staphylococcus aureus (MRSA)-induced footpad dermatitis (FPD). Eighty-four male Indian River (IR) broilers were randomly allotted to six different dietary treatments as follows: C-ve, C+ve, 10, 20, 30 and 40 ppm ZONPs from 7 to 49d of age. At day 28, broilers (n = 70) were sub-cutaneously injected with 0.5 ml of saline containing 5.3 × 107 CFU/ml of S. aureus (MRSA) in each metatarsal foot pad. Control (non-infected) broilers were given 0.5 ml of saline (n = 14). Results clarified that non-infected birds and ZONPs-fed birds had significantly higher standing and feeding activities and lower resting activities in comparison with the infected group. Also, the S. aureus infected group had significantly lower body weight gain (BWG) and higher feed conversion ratio (FCR) than the non-infected group. In addition, the non-infected birds and ZONPs groups had significantly lower object crossing and tonic immobility times (TI) and gait scores (GS) in comparison with the S. aureus group. Only ZONPs 30, 40 ppm and non-infected groups had a significantly higher latency to lie time (LLT) and lower serum cortisol level in comparison with the S. aureus group. Moreover, there were significant changes in the gross lesion score and histopathological lesions between the different groups. In conclusion, the dietary supplementation of ZONPs can reduce S. aureus-induced negative effects of FPD in broilers.

A case of clubbed down syndrome in broilers

This study presents a case of clubbed down syndrome in conventional broilers. During the first week of life, severe growth retardation was observed in approximately 25% of the flock. The growth-retarded chicks weighed only 45 g and showed a typical feather disorder which was most apparent on their abdomen and was defined in literature as typical for clubbed down syndrome. Necropsies, histology, biochemical analysis of blood and liver samples, serology and different PCR tests were performed in broilers to assess the aetiology of the clinical signs that were present in the affected broiler farm. Because of the suspicion of a possible link with the broiler-breeder farms, different investigations including serology, PCR and feed analysis were also performed on these farms. The results suggest that an accidentally excessive amount of calcium and iron in the feed of broiler-breeders, 3 weeks prior to first clinical signs in broilers, led to the development of clubbed down in the offspring, because of a relative Zn-deficiency in broiler-breeders and an absolute Zn-deficiency in the hatching eggs that were produced during this period. This appeared to be a reversible process as no clinical signs were observed in younger offspring of these broiler-breeders after they had consumed more of the new batch of feed. A potential involvement of Astrovirus could not be completely ruled out. This study demonstrates the importance of correct mineral concentrations in broiler-breeder feed and the impact it can have on the development of the offspring.

First report of Dermoglyphus passerinus (Analgoidea: Dermoglyphidae) and Strelkoviacarus sp.(Analgidae: Anomalginae) in canaries (Serinus canaria domestica) in Mexico

Feather mites are the most numerous group of symbionts permanently associated to birds. They are highly specialized to particular microhabitats on their hosts and most of them may be considered as commensals, but several species are parasites. This manuscript documents for the first time a combined infestation by quill mites Dermoglyphus passerinusGaud, 1974 (Analgoidea: Dermoglyphidae) and feather mites Strelkoviacarus sp.(Analgidae: Anomalginae), in domestic canaries (Serinus canaria domestica) (Linnaeus, 1758) (Passeriformes: Fringillidae) in Mexico City, Mexico. Description of the case, the feather and skin lesions, and findings associated with the infection are presented. This manuscript aims to contribute to the knowledge of mite species that can affect the plumage of Serinus canaria domestica; as well as to the diagnosis and control of these infestations.

Rearing and handling injuries in broiler chickens and risk factors for wing injuries during loading

Some injuries to broilers occur during rearing, but most injuries occur during handling before slaughter. Records provided by a processing plant for loads transported over a 19 mo period during 2009 and 2010 were examined. The median percentage of wing injuries per load was 5.7%, whereas injuries to the legs, breast, or shoulders were all less than 1% per load. Risk factors for wing injuries were examined by considering the data from each load by handling event (i.e., loads originating from the same producer on the same date). A multilevel model with three levels, producer (n = 86), handling event (n = 1694), and load (n = 4219), was fitted. The final model included weight, sex, season, catching team, time of day at which loading began, speed of loading, and an interaction between speed of loading and time of day. Factors that reduced the risk of wing injuries were loading lighter birds, loads containing only cockerels, and loading in the fall. The predicted percentage of wing injuries was relatively constant for slower loading speeds, but it was increased significantly when faster loading speeds were adopted during daytime (0700–1700). Identification of these risk factors can be used to adjust loading practices.

A Melanin bleaching method to prevent non-specific immunostaining of chicken feathers

Melanin in pigmented organs like the skin is known to react with 3,3′-diaminobenzidine (DAB) to give a brown colour indistinguishable from the colour that DAB imparts to target antibodies bound to specific antigens. This can lead to false positives in chicken feathers during immunoperoxidase staining. Here, we present a simple, fast and practical method for bleaching chicken feathers which can be applied prior to immunohistochemistry staining without affecting specific antigen-antibody binding. To our knowledge, this is the first report of a melanin-bleaching technique prior to immunoperoxidase staining techniques of chicken feathers for detection of pathogens. Optimisations of the method include:•

Removal of melanin from tissue sections using a short incubation with potassium permanganate followed by incubation with oxalic acid prior to immunostaining for improved specificity.

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This technique did not affect the antigenicity of infectious laryngotracheitis virus antigen and did not cause damage or detachment of tissues from the slides.

Anatomy of avian rictal bristles in Caprimulgiformes reveals reduced tactile function in open-habitat, partially diurnal foraging species

Avian rictal bristles are present in many species of birds, especially in nocturnal species. Rictal bristles occur along the upper beak and are morphologically similar to mammalian whiskers. Mammalian whiskers are important tactile sensors, guiding locomotion, foraging and social interactions, and have a well‐characterised anatomy. However, it is not yet known whether avian rictal bristles have a sensory function, and their morphology, anatomy and function have also not been described in many species. Our study compares bristle morphology, follicle anatomy and their association with foraging traits, across 12 Caprimulgiform species. Rictal bristle morphology and follicle anatomy were diverse across the 12 species. Nine of the 12 species had mechanoreceptors around their bristle follicles; however, there was large variation in their musculature, mechanoreceptor numbers and bristle morphology. Overall, species with short, thin, branching bristles that lacked mechanoreceptors tended to forage pre‐dusk in open habitats, whereas species with mechanoreceptors around their bristle follicle tended to forage at night and in more closed habitats. We suggest that rictal bristles are likely to be tactile in many species and may aid in navigation, foraging and collision avoidance; however, identifying rictal bristle function is challenging and demands further investigation in many species.

Sterile traumatic panniculitis in a captive Brent goose

A captive, adult female Brent goose (Branta bernicla) with a history of severe feather picking by its mate, was presented with 0.5-2.5 cm skin nodules on the head and neck. Histologic examination revealed a well-delineated dermal mass that surrounded an intact feather follicle and was composed of lakes of proteinaceous fluid and fibrin with scattered foamy macrophages and multinucleate giant cells. No bacteria or fungi were identified with histology, microbial culture, or PCR. Sterile panniculitis is an infrequent finding in animals and traumatic panniculitis is rarely sterile.

Histologically validated scoring system for the assessment of hock burn in broilers

The assessment of bird-based welfare indicators plays an important role in the evaluation of bird welfare. The aim of the study was to histologically validate a visual scoring system for hock burn in broilers and to detect threshold values of a visual score to define welfare-relevant alterations in terms of mild lesions or ulcers of the hock. We collected 200 hocks of 39- to 42-day-old Ross 308 broilers after the slaughter process. Each hock was scored visually ("macro scores" 0-4) and evaluated histologically ("micro scores" 0-3), with high scores representing more severe lesions. Although we found a tendency for higher micro scores with increasing macro scores, an exact allocation of macro to micro scores was not possible. For example, macro score 1 could represent micro scores 1, 2 and 3, whereas macro scores 3 and 4 always represented micro score 3 (ulcer). The conditional probability of certain micro scores for given macro scores was estimated using a multinomial logistic regression model. Ulcer showed the highest probability at macro score 1, whereas mild lesions were not found to have an estimated highest probability at any macro score. The depth of inflammation of hock burn lesions increased with increasing macro scores up to macro score 3 with an average depth of 1019 µm. Visually more severe and deeper lesions were also histologically rated with higher scores. Thus, considering limitations, the herein validated macroscopic assessment scheme for hock burn allows an estimation of histological alterations in hocks of broilers.RESEARCH HIGHLIGHTS Histological validation of a visual assessment scheme for hock burn in broilers.Tendency for higher micro scores with increasing macro scores.Estimation of histological score via macro score possible with limitations.Histological depth of inflammation increased with an increasing macro score.

Integumentary structure and composition in an exceptionally well-preserved hadrosaur (Dinosauria: Ornithischia)

Preserved labile tissues (e.g., skin, muscle) in the fossil record of terrestrial vertebrates are increasingly becoming recognized as an important source of biological and taphonomic information. Here, we combine a variety of synchrotron radiation techniques with scanning electron and optical microscopy to elucidate the structure of 72 million-year-old squamous (scaly) skin from a hadrosaurid dinosaur from the Late Cretaceous of Alberta, Canada. Scanning electron and optical microscopy independently reveal that the three-dimensionally preserved scales are associated with a band of carbon-rich layers up to a total thickness of ∼75 microns, which is topographically and morphologically congruent with the stratum corneum in modern reptiles. Compositionally, this band deviates from that of the surrounding sedimentary matrix; Fourier-transform infrared spectroscopy and soft X-ray spectromicroscopy analyses indicate that carbon appears predominantly as carbonyl in the skin. The regions corresponding to the integumentary layers are distinctively enriched in iron compared to the sedimentary matrix and appear with kaolinite-rich laminae. These hosting carbonyl-rich layers are apparently composed of subcircular bodies resembling preserved cell structures. Each of these structures is encapsulated by calcite/vaterite, with iron predominantly concentrated at its center. The presence of iron, calcite/vaterite and kaolinite may, independently or collectively, have played important roles in the preservation of the layered structures.

Liposarcoma in a Backyard Silkie and Retrospective Summary of Neoplasms Diagnosed in Backyard Chickens Submitted to the California Animal Health and Food Safety Laboratory System, 2008-2017

Liposarcomas are a malignant neoplasm of adipocytes, and are rarely diagnosed in avian species. This case report describes the evidence supporting a diagnosis of metastatic liposarcoma in a backyard silkie chicken. On September 28, 2017, a dead 3-yr-old backyard silkie chicken, with a history of unknown skin lesions involving the entire body and severe weight loss, was submitted to California Animal Health and Food Safety Laboratory System-Turlock branch for necropsy. At necropsy, raised necrotic lesions involving the majority of the skin and multiple nodules in the liver, spleen, and bone marrow were noticed. Microscopically, stellate, spindle, and myxoid cells containing large vacuoles, which were confirmed as lipid droplets by Oil Red O, were observed infiltrating the dermis and underlying a necrotic epidermis, with metastasis to liver, spleen, bone marrow, and ovary being the most significant findings. PAS, Oil Red O, Ziehl-Neelsen, Congo red, Gram, and Von Kossa stains, along with immunohistochemistry for pan cytokeratin, vimentin, S100, CD3, pp38, and Meq were used to classify the lesions. Intensely positive vimentin immunohistochemistry, along with large quantities of Oil Red O-positive lipid droplets within the neoplastic cells, were supportive of our diagnosis of liposarcoma. The incidence of neoplastic diseases diagnosed in backyard flock submissions to CAHFS system wide from 2008 to 2017 was also reviewed.

Mechanical removal (epidermal scarification) of pododermatitis injuries reduces the presence of both inflammatory tissue and its associated microbiota in broiler feet

Chicken feet have become an important commodity in the international market, representing a significant portion of poultry products exported by countries such as Brazil and the USA. However, the presence of pododermatitis in the footpad is an important barrier to exportation, since importing countries do not accept injured feet or allow the use of automatic equipments to remove the affected tissue. The objective of this research was to evaluate the impact of using an automatic equipment to remove injuries of pododermatitis on histological and microbiological traits of broiler feet processed according to commercial practices. A total of 240 broiler feet obtained from a commercial processing plant was visually classified according to the degree of pododermatitis and distributed in a 4 × 2 factorial arrangement, totalizing eight treatments with 30 replications. Factors were feet classification (1 to 4) and injury removal (yes or no). Feet were sampled for microbiological and histological analysis before and after the mechanical removal of pododermatitis injuries by an automatic machine that promoted footpad epidermal scarification. No significant interaction between feet classification and injury removal was detected for any of the analyzed variables. Also, no significant effect of feet classification was detected on aerobic plate counts, total coliforms and Escherichia coli. Feet inflammation score tended to increase (P = 0.06) according to the downgrading of feet classification, but the mechanical removal of pododermatitis injuries reduced feet inflammation score (P < 0.01), total coliform counts (P = 0.01), and E. coli (P = 0.01) independently of feet classification. Together, these results demonstrate the efficacy of the automatic equipment in removing both the inflammatory tissue and its associated microbiota in broiler feet affected by pododermatitis. Therefore, in addition to the already authorized use of blades, the use of automatic equipments for epidermal scarification in the processing of broiler feet deserves further consideration by the regulatory agencies.

Investigation into diseases in free-ranging ring-necked pheasants (Phasianus colchicus) in northwestern Germany during population decline with special reference to infectious pathogens

The population of ring-necked pheasants (Phasianus colchicus) is decreasing all over Germany since the years 2008/2009. Besides impacts of habitat changes caused by current rates of land conversion, climatic influences or predators, a contribution of infectious pathogens needs also to be considered. Infectious and non-infectious diseases in free-living populations of ring-necked pheasants have been scarcely investigated so far. In the present study, carcasses of 258 deceased free-ranging pheasants of different age groups, predominantly adult pheasants, collected over a period of 4 years in the states of Lower Saxony, North Rhine–Westphalia and Schleswig-Holstein, were examined pathomorphologically, parasitologically, virologically and bacteriologically, with a focus set on infectious pathogens. A periocular and perinasal dermatitis of unknown origin was present in 62.3% of the pheasants. Additional alterations included protozoal cysts in the skeletal musculature (19.0%), hepatitis (21.7%), enteritis (18.7%), gastritis (12.6%), and pneumonia (11.7%). In single cases, neoplasms (2.6%) and mycobacteriosis (1.7%) occurred. Further findings included identification of coronaviral DNA from trachea or caecal tonsils (16.8%), siadenoviral DNA (7.6%), avian metapneumoviral RNA (6.6%), and infectious bursal disease viral RNA (3.7%). Polymerase chain reaction (PCR) on herpesvirus, avian influenza virus (AIV), paramyxovirus type 1 (PMV-1), avian encephalomyelitis virus (AEV), and chlamydia were negative. Based on the present results, there is no indication of a specific pathogen as a sole cause for population decline in adult pheasants. However, an infectious disease can still not be completely excluded as it may only affect reproduction effectivity or a certain age group of pheasants (e.g., chicks) which were not presented in the study.

Gangrenous dermatitis in chickens and turkeys

Gangrenous dermatitis (GD) is a disease of chickens and turkeys that causes severe economic losses in the poultry industry worldwide. Clostridium septicum, Clostridium perfringens type A, and occasionally Clostridium sordellii are considered the main causes of GD, although Staphylococcus aureus and other aerobic bacteria may also be involved in some cases of the disease. GD has become one of the most significant diseases of commercial turkeys in the United States. Several infectious and/or environmental immunosuppressive factors can predispose to GD. Skin lesions are considered to be the main portal of entry of the microorganism(s) involved. GD is characterized by acute onset of mortality associated with gross skin and subcutaneous tissue lesions consisting of variable amounts of serosanguineous exudate together with emphysema and hemorrhages. The underlying skeletal muscle can also be involved. Ulceration of the epidermis may be also noticed in cases complicated with S. aureus. Microscopically, necrosis of the epidermis and dermis, and subcutaneous edema and emphysema are commonly observed. Gram-positive rods can be identified within the subcutis and skeletal muscles, usually associated with minimal inflammatory infiltrate. A presumptive diagnosis of GD can be made based on history, clinical signs, and gross anatomic and microscopic lesions. However, confirmation should be based on demonstration of the causative agents by culture, PCR, immunohistochemistry, and/or fluorescent antibody tests.

Effects of breeder feeding restriction programs and incubation temperatures on progeny footpad development

Footpad dermatitis begins early in life, and there is evidence of individual susceptibility. An experiment was conducted to evaluate the carryover effects of breeder feed restriction programs and incubation temperatures (TEM) on progeny footpad development at hatch, and 7 and 22 d. Cobb 500 fast feathering breeders were subjected to 2 dietary feed restriction programs during rearing: skip-a-day (SAD) and every-day feeding (EDF). At 60 wk of age, eggs from each group were collected and incubated according to 2 TEM, standard (S) eggshell temperature (38.1°C) and early-low late-high (LH). This second profile had low (36.9°C) eggshell temperature for the first 3 d, and standard temperature until the last 3 d when eggs were subjected to elevated (38.9°C) eggshell temperature. At hatch, 15 chicks from each treatment combination were sampled to obtain footpads for histological analysis. Seventy-two chicks per treatment were placed in 48 cages (6/cage), and raised to 22 d. At 7 and 22 d, 1 and 2 chickens, respectively, were sampled for footpads. The BW and group feed intake were recorded to obtain BW gain and feed conversion ratio at 7 and 21 d. Histological analysis assessed thickness and total area of stratus corneum (SC), epidermis, and dermis, and total papillae height. Data were analyzed as randomized complete block design in a 2 × 2 factorial arrangement of treatments. There was a negative effect of LH TEM on performance at both ages. An interaction effect on SC area and papillae height was observed at hatch. Additionally, SAD treatment increased thickness and area of footpad dermis. At 7 d, the SC parameters of the SAD progeny were increased. Epidermis thickness was affected by treatment interaction. Furthermore, LH TEM decreased epidermis thickness and dermis area. At 22 d, interaction effects were observed in thickness and area of SC and epidermis. Incubation S TEM increased thickness and area of dermis. It was concluded that breeder feed restriction programs and incubation TEM profiles may have carryover effects on histomorphological traits of footpads.

Marek's disease virus and skin interactions

Marek's disease virus (MDV) is a highly contagious herpesvirus which induces T-cell lymphoma in the chicken. This virus is still spreading in flocks despite forty years of vaccination, with important economical losses worldwide. The feather follicles, which anchor feathers into the skin and allow their morphogenesis, are considered as the unique source of MDV excretion, causing environmental contamination and disease transmission. Epithelial cells from the feather follicles are the only known cells in which high levels of infectious mature virions have been observed by transmission electron microscopy and from which cell-free infectious virions have been purified. Finally, feathers harvested on animals and dust are today considered excellent materials to monitor vaccination, spread of pathogenic viruses, and environmental contamination. This article reviews the current knowledge on MDV-skin interactions and discusses new approaches that could solve important issues in the future.

Enzootic outbreak and spontaneous regression of keratoacanthomas in a commercial layer flock

This paper reports an enzootic outbreak and spontaneous regression of keratoacanthomas among adult layer hens with lesions on the skin of the legs. The observations were performed in a flock of 55,000 commercial layers (50,000 Lohmann White and 5,000 Lohmann Brown). At the age of 30 weeks, Lohmann White layers exhibited a number of growths (at an average of 60 hens per week, representing 0.1% of the flock) in the region of leg toes on a daily basis over 28 weeks that regressed during the remaining flock production period. Gross and histological investigations identified the lesions as keratoacanthomas. PCR analysis was negative for avian leukosis virus (ALV) and reticuloendotheliosis virus (REV). The present investigations have revealed an unusual case: this is the first report on an enzootic outbreak of multiple keratoacanthomas in commercial layers. The results of the aetiological investigations do not show a relation to any infectious agent or a chemical-toxic cause. The abnormal invasion of keratinocytes from the stratum corneum leading to neoplasms in this case coincides with the phase of peak laying capacity which is in fact a stress factor and might be regarded as a provocative moment.

The first report of Knemidocoptes intermedius Fain et Macfarlane, 1967 (Acari: Astigmata) in naturally infected European birds

According to the latest taxonomical review, the genus Knemidocoptes (Epidermoptidae: Knemidocoptinae) comprises 15 species of mites responsible for skin lesions on the face, legs, or body of various wild and domestic birds. A number of 54 common ravens, Corvus corax (Aves: Passeriformes: Corvidae) were found dead (accidental poisoning) in March 2009, in Târgu Mureş, Romania. One individual presented bilateral symptoms of scaly leg disease. Microscopic examination revealed the presence of Knemidocoptes intermedius (Epidermoptidae, Knemidocoptinae) in one bird. The lesions were present on both feet (bilateral) and consisted of moderate hypertrophic crusts on the dorsal and ventral part of the toes as well as the distal part of the tarsometatarsal region. It is the first reliable record of K. intermedius in Europe and also the first record of this species in the common raven. The host range and specificity of this parasite is discussed, along with a revision of occurrences in wild birds.

Effects of high dietary levels of soybean meal and its constituents (potassium, oligosaccharides) on foot pad dermatitis in growing turkeys housed on dry and wet litter

Soybean meal (SBM) is the main protein source in diets for turkeys. High dietary levels of SBM are thought to increase the incidence of foot pad dermatitis (FPD). Therefore, this study was conducted to test potential effects of high SBM and to elucidate which constituents in SBM might be associated with the development of FPD. Two week-old female turkeys were allotted to four groups of 29 birds each, and housed on dry wood shavings in floor pens over a period of three weeks. Four different diets were fed: control, high SBM, high potassium (K) or high oligosaccharide (OL) diet. Additionally, for only 8 h/d half of the animals in each group were exposed to wet litter (27% DM) in adjacent separate boxes. The foot pads of all birds were assessed on days 0, 7, 14 and 21 for external lesions. For the histopathology of the foot pads, on day 0 three birds from each group, and on days 7 and 14 six birds per feeding group were selected. The remaining birds in each group were sacrificed on day 21 and their pads were evaluated histologically. High dietary levels of SBM, potassium or oligosaccharides did not influence the severity of FPD on dry litter, but slightly increased the severity on wet litter. However, there were no histopathological differences in FPD severity between these dietary treatments within each litter form compared to the control. Nevertheless, the FPD severity was in general higher on wet litter. Thus, litter moisture appears to be one of the most important factors involved in FPD in turkeys. In addition, all nutritional factors which increase water intake and excreta or litter moisture may contribute to an increased development and severity of FPD in turkeys.

Some observations on naturally occurring neoplasms of domestic fowls in the State of Victoria, Australia (1977-87)

In the 10 years to November 1987, 33 different types of naturally occurring neoplasms were diagnosed in 2281 domestic fowls submitted for necropsy examination. The most prevalent type was lymphoma (1825/2281 = 80%) including two cases in chickens from a flock free from Marek's disease virus, exogenous avian leukosis viruses and reticuloendotheliosis virus; the remaining lymphomas were diagnosed on gross and/or histological criteria as Marek's disease (1069) or lymphoid leukosis (754). Of the non-lymphoid neoplasms, leiomyomas of the ventral ligament of the oviduct (99) were the most common followed closely by metastatic abdominal adenocarcinomas (93) and haemangiomas or haemangiosarcomas (91). A large number of fibromas and fibrosarcomas (40), and a smaller number of myxomas and myxosarcomas (17) were observed. Three fibrosarcomas and two myxosarcomas were presented as metastatic abdominal neoplasms, and two fibromas and seven myxomas were found on the rostral extremity of the upper beak of hens, including five cases of myxoma from one flock. Other less prevalent neoplasms described were myelocytomas or myeloblastomas (12), avian keratoacanthomas (11), granulosa-theca cell tumours (11), oviduct adenomatosis and adenocarcinomas (10) and ovarian adenocarcinomas (8). Small numbers of some neoplasms or well-characterized variants were encountered, namely histiocytic sarcomas (5), lipomas (4), liposarcomas (2), reticulum cell sarcomas (3), plasmacytomas (3), intracutaneous keratinizing epitheliomas (3), feather folliculomas (2), proventricular adenomas (2), hepatocellular adenocarcinomas (2), cholangiocellular adenomas and adenocarcinomas (6), pancreatic adenocarcinomas (3), nephroblastomas (7), astrocytomas (5), pinealomas (3), Schwannomas (3) and multifocal melanomas (3). Single examples were found of osteoma, osteosarcoma, rhabdomyosarcoma, leiomyoma of the gizzard wall, intestinal adenocarcinoma, renal adenocarcinoma, adrenocortical adenoma and ultimobranchial cyst.

Multiple feather follicle cysts in a Moroseta hen (Gallus gallus)

An 8-month-old white feathered, black skinned Moroseta hen was presented for examination because of numerous 2 mm- to 30 mm-diameter irregularly shaped, hard nodules in the skin of the head, wings, back, and abdomen. The nodules were confined to the skin and did not involve subcutaneous tissues. Nodules consisted of dilated feather follicles packed with a caseous tan-to-pale-yellow material admixed with feather remnants. Histologically, affected feather follicles were markedly dilated and filled with laminated keratin debris. Necrosis of the epidermis and perifollicular lymphocyte infiltration was also present. Bacteriologic investigation of internal organs was negative, while secondary bacteria, Proteus spp. and Bacillus spp., were isolated from skin nodules. A concomitant lice infestation of Menopon spp., as well as leg mange caused by Cnemidocoptes spp., were also present. These bacterial isolates and parasites were not related to the disease condition. The condition observed was differentiated from benign feather follicle tumors, and a diagnosis of multiple feather follicle cysts was made. In addition, a breed predisposition was hypothesized.

The contribution of feathers in the spread of chicken anemia virus

Chicken anemia virus (CAV) spreads vertically and horizontally, however, the process is mostly still obscure. To further clarify the horizontal CAV spread, we examined the contribution of feathers. We demonstrated that CAV could be amplified from DNA purified from feather shafts of experimentally infected chicks, and the process efficacy was evaluated by comparing the amplification of DNA purified from feather shafts and lymphoid organs of CAV-experimentally infected chicks. DNA from feathers was found as an efficient source for CAV detection. Further, to substantiate whether CAV reaches the feather shafts passively via the blood, or intrinsically, causing histopathological changes, the feather follicle tissues were examined for CAV-induced lesions. Specific histological changes were found, however, immunohistochemistry failed to detect viral proteins. To determine whether the feather shafts are a source of infective virus, they were homogenized and used to infect 1-day-old chicks via the mucosal entries (eyes, nose and oropharynx). That infection mode simulates the natural route of horizontal infection in commercial poultry houses. We demonstrated the CAV-infection by serology, virology and pathology, showing that feather shafts carry infectious CAV either on their surface or within their feather pulp, and concluded that feathers contribute to the horizontal CAV dissemination.

Investigations on the aetiology of pinching off syndrome in four white-tailed sea eagles (Haliaeetus albicilla) from Germany

The purpose of this study was to investigate the aetiology of the pinching off syndrome (POS), a generalized feather abnormality affecting free-living nestling of the white-tailed sea eagle (Haliaeetus albicilla) in Europe. For the first time, extensive clinical, haematological, biochemical, virological, bacteriological, nutritional, histopathological, parasitological and electron microscopical examinations were performed on three females and one male suffering from POS. Early and increased cytokeratin formation at the base of regenerating feathers and their follicle was observed in affected birds. Ultrathin sections of the feather papillae revealed an extended stratum transitivum and a compact, thickened keratinized stratum corneum. The transitional cells in POS feathers contained vacuoles often associated with the nucleus. Lipofuscin accumulations in neurons, glial cells and islet cells of the pancreas were found in all examined birds. It was not clear whether there is an association between the occurrence of lipofuscin and POS. No evidence was found to suggest that infectious agents (parasites, bacteria, fungi or viruses), malnutrition or hormonal imbalances are involved in the aetiology of POS in white-tailed sea eagles. It remains unclear whether there is a genetic background of POS.

Variations in the morphology, distribution, and arrangement of feathers in domesticated birds

Domesticated birds exhibit a greater diversity in the morphology of their integument and its appendages than their wild ancestors. Many of these variations affect the appearance of a bird significantly and have been bred selectively by poultry and pigeon fanciers and aviculturists for the sake of visual appeal. Variations in feather distribution (e.g., feathering of legs and feet, featherless areas in normally feather-bearing skin) are widespread in chickens and pigeons. Variations in the number of feathers (e.g., increased number of tail feathers, lack of tail feathers) occur in certain pigeon and poultry breeds. Variations in feather length can affect certain body regions or the entire plumage. Variations in feather structure (e.g., silkiness, frilled feathering) can be found in exhibition poultry as well as in pet birds. Variations in feather arrangement (e.g., feather crests and vortices) occur in many domesticated bird species as a results of mutation and intense selective breeding. The causes of variations in the structure, distribution, length and arrangement of feathers is often unknown and opens a wide field for scientific research under various points of view (e.g., morphogenesis, pathogenesis, ethology, etc.). To that extent, variations in the morphology, distribution and arrangement of feathers in domesticated birds require also a concern for animal welfare because certain alleles responsible for integumentary variations in domesticated birds have pleiotropic effects, which often affect normal behaviour and viability.

Electron microscopical observations of psittacine beak and feather disease in an Umbrella cockatoo (Cacatua alba)

Psittacine beak and feather disease (PBFD) was diagnosed in an umbrella cockatoo (Cacatua alba) with severe feather dystrophy and loss. Electron microscopically, the intranuclear and intracytoplasmic inclusion bodies observed by light microscopy were composed of viral particles forming paracrystalline arrays, whorls, semicircles or concentric circles. Recovered viral particles from the skin and feather follicle tracts were icosahedral and 15 to 20 nm in diameter.

Experimentally induced selenosis of adult mallard ducks: clinical signs, lesions, and toxicology

Selenosis is thought to be a significant problem among waterfowl populations in selenium-contaminated wetlands in the western United States. Chemical analysis of avian tissues is currently the principal basis for diagnosis. The purpose of these two 150-day studies was to establish whether morphological criteria for selenosis could be developed to supplement chemical analysis. Forty-eight flightling male mallard ducks were fed either a proprietary waterfowl ration (< 1 ppm selenium) or the same ration amended to contain 10, 25, and 60 ppm selenium supplied as seleno-L-methionine (n = 12/group). In a separate study, 12 birds fed twice daily were offered either a proprietary ration or a selenium-supplemented ration (120 microg/g) for one of two daily feedings. Selenium in whole blood increased from baseline concentrations (< 0.4 microg/ml) to means of 4.5, 8.9, and 16.0 microg/ml in the 10-, 25-, and 60-ppm groups, respectively. All birds in the 60-ppm-dose group rapidly lost weight and were killed (11/12) or died (1/12) between 22 and 50 days of dietary exposure. In addition to emaciation, six of 12 birds (50%) fed the 60-microg/g diet developed mild to moderate generalized hepatopathy with single-cell necrosis, karyomegaly of hepatocytes, hyperplastic bile duct epithelium, and/or iron accumulation in Kupffer cells. The principal lesions in birds exposed to other dietary concentrations of selenium involved integumentary structures containing hard keratin. Gross lesions developed after 76 days of dietary exposure and consisted of bilaterally symmetrical alopecia of the scalp and dorsal cervical midline, broken or lost digital nails, and necrosis of the tip of the beak (maxillary nail). One or more of these three lesions were present in 0/12 birds (0%) fed 10 ppm selenium, 5/12 birds (42%) fed 25 ppm selenium, and 4/9 (44%) birds fed a split-feed diet containing 120 ppm selenium. Controls were unaffected. Histologic lesions in digital and maxillary nails consisted of single-cell to full-thickness necrosis of keratinocytes and multifocal parakeratosis in stratum corneum. Histologic lesions in alopecic skin (necrosis of the epidermal collar, inflammation of the feather pulp, and follicular keratosis) were mild. Some birds with alopecia had no detectable lesions in feather follicles from affected areas of skin. The highest tissue concentrations of selenium were in liver, kidney, and feathers, respectively. Mean hepatic tissue concentrations were 14.5 microg/g (10 ppm group), 29.6 microg/g (25 ppm group), 60.6 microg/g (60 ppm group), 13.0 microg/g (120 ppm split-feed group), and 2.0 microg/g (controls). Integumentary and hepatic lesions may be of value in corroborating a diagnosis of selenosis based on chemical analysis of tissues from naturally intoxicated waterfowl. Some birds with fatal selenosis may have no morphologic lesions other than emaciation.

Multiple cutaneous capillary haemangioma in a red partridge (Alectoris rufa)

A 6-year-old healthy decoy red partridge (Alectoris rufa) developed rapidly growing multiple cutaneous nodules in the dorsal aspect of the neck. Histologically, they were distinctly exophytic growths composed of variably-sized blood vessels often surrounded by solid masses of endothelial-like cells set in an oedematous stroma with abundant inflammatory cells. They were diagnosed as multiple cutaneous capillary haemangiomas. These tumours have been described in chickens in association with viral infections and in old budgerigars, but not in partridges.

Avian keratoacanthoma (dermal squamous cell carcinoma) in broiler chicken carcasses

Multiple lesions of dermal squamous cell carcinoma are found at a low frequency (0.04%) in the carcasses of young meat-type chickens at slaughter. For this study, affected carcasses (n = 308) were removed from the processing line, and lesions were characterized by size, distribution, and morphology. Carcasses were also sexed and examined for evidence of metastasis. Nodular (n = 297) and ulcerative (n = 1,707) lesions were counted and examined. Most lesions were present in the pectoral, dorsopelvic, and femoral feather tracts. Few lesions (n = 11) were found in wing tracts. Mean diameter was 5.4 mm for ulcerative lesions and 3.1 mm for nodular lesions. Histologic sections of ulcerative (n = 579) and nodular (n = 113) lesions were examined. Small nodular lesions originated from hyperplastic feather follicle epithelium. Nodules contained keratin-filled cysts lined by squamous epithelium that were associated with isolated islands and infiltrating cords of dermal keratinocytes. Loss of surface epithelium resulted in noduloulcerative and ulcerative lesions. Invasion of underlying skeletal muscle and evidence of visceral metastasis were not present, but invasion through elastic laminae and into the subcutis was present in 20.5% (134/654) of the lesions examined. The nodular lesions in these carcasses were morphologically similar to early nodular lesions previously described in live chickens as avian keratoacanthomas. A retrospective study compared selected production parameters and disease condemnations to the prevalence of squamous cell carcinoma in 665 flocks of broiler chickens. There was a positive correlation (P < 0.0001) with the occurrence of airsacculitis but a negative correlation with increased age and condemnations for leukosis (P < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Disorders of the avian integument

The avian integument consists of highly specialized structures that show extreme variations between species. Feathers are the most obvious part of the integument, and their color and beauty forms an important basis for the attraction of birds to humans. Any disorder in the feathers can be distressing for a client and frustrating for the avian practitioner. The cause of some disorders may be apparent, but others have a complex pathogenesis involving management, human-bird interaction, malnutrition, psychologic factors, disease, or hormone imbalances.

Extracutaneous viral inclusions in psittacine beak and feather disease

Thirty-five birds that died with naturally acquired psittacine beak and feather disease (PBFD) were necropsied to identify extracutaneous viral inclusions. Inclusions were found in various tissue sections from 34 of 35 birds. By immunoperoxidase staining, intranuclear and intracytoplasmic inclusion bodies were shown to contain PBFD viral antigen. Inclusion-bearing lesions were widely disseminated but often closely associated with the alimentary tract. Lesions within the palate, esophagus, crop, intestine, bursa of Fabricius, and liver probably serve as sources for viral shedding into the feces.