Epitheliogenesis imperfecta or Aplasia cutis congenita is a very rare and clinically characteristic recessively inherited sporadic dermatological disorder affecting many species of domestic animals and man encompassing diverse group of disorders of various etiologies and severity. This is characterized by discrete areas on the body that are devoid of skin at the time of birth often presenting small erythematous and ulcerated or scar-like alopecic skin lesions. This condition is reported in many domestic animals including pigs¹, most frequently in Large white and Saddleback breeds, cattle², horses³ and wild animal species such as pumas⁴. In human beings, this can contribute to 0.3% of total live births⁵.

Among the domestic pigs, the condition is characterized by single piglet or group of piglets of the same litter getting affected with minimal localized involvement of feet and face to severe life-threatening generalized blistering, eye defects, gastrointestinal, tooth, nail and tracheal abnormalities often ending with death of the animals⁶. As the natural immunity offered by the skin is lost, the exposed dermis in the affected animals will undergo ulceration and allow the entry of multiple opportunistic infectious agents making the animal patients incompatible to life. Although, surgical correction of the affected skin is usually advised to save the life of animals in other species⁷, better managemental practices are ideal considering economics in pigs. The current study was undertaken to study the gross and histopathological features as diagnostic tools for the confirmation of epitheliogenesis imperfecta and evaluate conservative approach to save the life of suffering piglets.

The first incident was recorded in a village called Agasarahatti in Alur Taluk of Hassan District in an organized large white Yorkshire farm. Among 12 piglets born in the litter (Male: 7; Female: 5), 8 piglets (Male: 4; Female: 4) had clinical lesions of EI with skin malformation on facial, leg and dorsal areas of the body that were devoid of epidermis and hairs (Fig. 1). The piglets appeared anemic and severely dehydrated with a rectal temperature of 40 ± 1° Celsius. However, two piglets that were deeply comatosed at the time of clinical examination showed subnormal temperature. The exposed dermis showed moderate to severe congestion with occasional areas of hemorrhages and inflammatory exudate. The impression smears prepared from the lesions showed the presence of mixed bacterial population. All the affected animals died before any therapeutic interventions were made. The post mortem investigation revealed pneumonic changes and moderate to severe catarrhal enteritis. Tissue samples collected were immediately fixed in 10% neutral buffered formalin. The samples were processed by routine paraffn embedding technique and sectioned at five micron thickness. The sections were stained with routine hematoxylin and eosin (H & E) and Masson’s Trichrome stains (MTS).

The second incident was recorded in the Institutional Livestock farm complex, Veterinary College Hassan in August 2021. The affected Large Yorkshire White piglets showed multiple areas of skin lesions more concentrated in legs and face that were devoid of epidermis, part of dermis and adnexae. The lesions were depressed and of varied sizes and were roughly circular and bright red initially and later got covered with brownish black crusty material. The pigs appeared anorectic, weak, anemic and ataxic upon physical examination. Few piglets had higher body temperature and dyspnea and respiratory rales. Among the 10 piglets (6 males and 4 females) born with the lesions, (total litter size: 14), 4 died (3 males and 1 female) before any therapeutic or managemental interventions were made. Six piglets were administered with 0.5 mL strepto-penicillin (Dicrysticin-S Inj, Zydus AHL. Streptomycin sulphate - 2.5 g, Procaine penicillin G 15,00,000 IU and Penicillin G sodium 5,00,000 IU reconstituted with 10 mL with water for injection) daily once for 5 days. The lesions were cleaned in diluted chloroxylenol based antiseptic solution (Dettol, Reckitt), applied with povidone-iodine based ointment (Cipladine, Cipla) daily and covered with a protective cotton bandaging for 10 days.

The surviving six animals showed scar formation in the lesions that progressively got reduced in size. Necropsy of the dead animals revealed purulent arthritis of hock joints, suppurative bronchopneumonia and enteritis. The lesion had depressed areas representing scar formation in the later stages.

Epitheliogenesis imperfecta refers to a congenital skin disorder characterized by discrete areas of the body that are devoid of skin noticed at the time of birth. This condition is reported in many domestic¹and wild animal species⁴ and human beings⁵.

In the current investigation, two outbreaks have been recorded in herds of Large Yorkshire White piglets near Hassan. The condition was clinically evident by multiple areas of skin lesions that were devoid of epidermis, part of dermis and adnexae. The piglets were anorectic, weak, anemic and ataxic. These observations are in accordance with the earlier findings¹. Before any therapeutic or managemental interventions were made, all the eight affected piglets in first outbreak and four in the second outbreak succumbed to systemic infections. The cause of mortality was mainly attributable to secondary infection leading to arthritis, diarrhea and pneumonia. As skin is one of the major innate barriers, they might have picked up the infection by breach in the skin, which might have led to pneumonia, arthritis and enteritis. This implied that the piglets suffering from EI were vulnerable to infections through discontinuous skin. The higher mortality in outbreak-1 could be attributable to late presentation of the piglets for treatment.

Histopathological examination of the skin revealed patchy loss of epidermis replaced with inflammatory exudates often exposing the dermis and epidermal hyperplasia, parakeratosis and hyperkeratosis in the adjacent areas (Fig. 2), presence of bacterial pathogens, increased and dysplastic hair follicles and connective tissue proliferation in the dermis. These microscopic changes are in line with the earlier findings⁷. However, epidermolysis bullosa externally characterized by cutaneous blisters reported⁷ was not observed in the current study.

In few places, the affected epidermal areas were detached and had formed gaps filled with inflammatory exudates and cell debris. Occasionally, formation of granulation tissue with infiltration of mononuclear inflammatory cells and intensely eosinophilic radiating structures resembling Splendore–Hoeppli bodies were noticed (Fig. 3). In addition, abnormally scattered, oriented and shaped dysplastic hair follicles were seen (Fig. 4). Blood vessels in the vicinity of the epidermal lesions were congested and hemorrhages were observed in the exposed dermis.

Few animals presented intensely eosinophilic radiating structures resembling Splendore-Hoeppli bodies. The Splendore-Hoeppli phenomenon is caused by the formation of intensely eosinophilic material around microorganisms such as fungi, bacteria, allergens and parasites or any other biologically inert substances. This has been observed in Corynebacterium ulcerans or Nocardia spp. in bovine nasal eosinophilic granulomas⁸, cutaneous botryomycosis in a crossbred domestic pig¹⁰ and a castrated male domestic short hair cat⁹. Further, it has been observed that cutaneous botryomycosis associated with Splendore-Hoeppli phenomenon can be caused by a variety of non-fi lamentous bacteria such as Staphylococcus aureus, Streptococcus species, Proteus species, Pseudomonas species and Actinobacillus species in domestic animals.Though the pathogenesis of Splendore-Hoeppli phenomenon is not clearly elucidated, hindrance to phagocytosis, antibody-antigen complex formation and intracellular destruction of bacteria has been postulated to be the reasons behind asteroid formation¹⁰ and it was also opined that cutaneous botryomycosis could be associated with immunosuppression¹⁰. Piglets in the current study would have been under stress due to EI lesions and concurrent infections that would have predisposed them to immunosuppression.

Six piglets from outbreak 2 were subjected to therapeutic intervention with administration of Strepto-Penicillin, wound dressing and protective bandaging. The broad spectrum antibiotic combination would have given protection against both Gram positive and Gram negative bacteria and protective bandaging would probably had acted as artifi cial skin or the barrier. The antibiotics and topical antiseptics are required to prevent secondary pyoderma that may potentially lead to septicemia.

A number of animal species have been reported to have epitheliogenesis imperfecta, and it is thought that this condition is an autosomal recessive in inheritance. The majority of lesions were distinguished by the loss of the epidermis and adnexae. Since the epidermis of the skin is an important external defence organ, the natural defence rendered by it will be lost in this condition making the piglets vulnerable for secondary infections. Timely diagnosis of the condition with systematic therapeutic intervention can aid in minimizing the mortality.

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