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Topic:Skin
The skin of horses is a complex organ that serves multiple functions, including protection, thermoregulation, and sensory perception. It consists of several layers, primarily the epidermis and dermis, each contributing to the overall health and functionality of the skin. The epidermis provides a barrier against environmental factors, while the dermis supports the skin structure and houses blood vessels, nerves, and hair follicles. Equine skin is also involved in the production of sweat and sebum, which aid in temperature regulation and skin lubrication, respectively. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, physiology, and health conditions of equine skin, as well as advancements in dermatological treatments and care practices.
An unexpected advantage of whiteness in horses: the most horsefly-proof horse has a depolarizing white coat. White horses frequently suffer from malign skin cancer and visual deficiencies owing to their high sensitivity to the ultraviolet solar radiation. Furthermore, in the wild, white horses suffer a larger predation risk than dark individuals because they can more easily be detected. In spite of their greater vulnerability, white horses have been highly appreciated for centuries owing to their natural rarity. Here, we show that blood-sucking tabanid flies, known to transmit disease agents to mammals, are less attracted to white than dark horses. We also demonstrate that tabanids use reflected pola...
Prevalence of infiltrative lymphocytic mural folliculitis in equine inflammatory skin diseases. Infiltrative lymphocytic mural folliculitis (ILMF) is a histopathological reaction pattern reported to occur in a small number of equine inflammatory dermatoses. However, the prevalence of ILMF in a variety of equine dermatoses has not been reported. Skin biopsy specimens from 250 horses with inflammatory dermatoses and from 27 horses with physically healthy skin were therefore evaluated. ILMF was present in 82% of the diseased skin specimens examined. ILMF was not seen in physically healthy skin. It appears that ILMF is frequently seen in a wide variety of equine inflammatory dermatoses and t...
Atypical Dermatophilus congolensis infection in a three-year-old pony. Dermatophilosis caused by Dermatophilus congolensis causes exudative dermatitis in a variety of species. The infection is generally limited to the cutaneous tissues, where infection is acquired from the environment and bacteria penetrate into keratinized epithelium through epithelial disruption. A 3-year-old pony filly was examined for enlarging mandibular lymph nodes during the preceding 10 months. Biopsy of the node revealed mixed and granulomatous inflammation and thick, filamentous Gram-positive bacteria. Dermatophilus congolensis, confirmed by biochemical testing and sequencing of the rib...
Identification of equine cutaneous lymphangioma by application of a lymphatic endothelial cell marker. An adult horse was presented with a mass located within the dermis and subcutis of the right forelimb. At post-mortem examination there was a marked increase in thickness of the subcutis of the right forelimb extending from the fetlock to the pectoral muscles. Microscopically, the dermis and subcutis were diffusely infiltrated by endothelial-like cells forming irregular channels and cavernous spaces. Immunohistochemical examination revealed the endothelial-like cells to express vimentin, factor VIII-related antigen and PROX-1, confirming the identity of the tumour as a lymphangioma. Ultrastruc...
Whole-genome scan identifies quantitative trait loci for chronic pastern dermatitis in German draft horses. Chronic pastern dermatitis (CPD), also known as chronic progressive lymphedema (CPL), is a skin disease that affects draft horses. This disease causes painful lower-leg swelling, nodule formation, and skin ulceration, interfering with movement. The aim of this whole-genome scan was to identify quantitative trait loci (QTL) for CPD in German draft horses. We recorded clinical data for CPD in 917 German draft horses and collected blood samples from these horses. Of these 917 horses, 31 paternal half-sib families comprising 378 horses from the breeds Rhenish German, Schleswig, Saxon-Thuringian, a...
Tissue engineering in wound repair: the three “R”s–repair, replace, regenerate. Horses are predisposed to traumatic wounds that can be labor intensive and expensive to manage. Skin has a considerable potential for efficient and functional repair however, while cutaneous repair is a regenerative process in the fetus, this capability declines in late gestation as inflammation and scarring alter the outcome of healing. The historical gold standard for replacement of lost skin is the autologous skin graft. However, the horse's lack of redundant donor skin limits the practicality of full-thickness grafting to smaller wounds; moreover, graft failure is relatively common in equi...
Comparison of characteristics and enzymatic products of leukocytes in the skin and laminar tissues of horses administered black walnut heartwood extract or lipopolysaccharide. To compare characteristics and enzymatic products of leukocytes detected in the skin and laminar tissues of horses administered black walnut heartwood extract (BWHE) and horses administered purified lipopolysaccharide (LPS). Methods: 25 healthy 5- to 15-year-old horses. Methods: Horses were randomly assigned to receive LPS (20 ng of O55:B5 Escherichia coli endotoxin/kg; n = 5) IV or 6 L of BWHE (10) or water (control group; 10) via nasogastric intubation. Horses were euthanatized 12 hours after treatment or at onset of Obel grade 1 lameness. Laminar tissue samples and skin samples from the mid...
Equine neutrophil elastase in plasma, laminar tissue, and skin of horses administered black walnut heartwood extract. Laminitis is a local manifestation of a systemic inflammatory response that is characterized by neutrophil activation and movement of neutrophils into the laminar tissues. Given the evidence for the involvement of neutrophils in the development of laminitis, we measured concentrations of neutrophil elastase, a serine protease released from the azurophilic granules of neutrophils, in plasma, skin and laminar tissues obtained from control horses and horses given black walnut heartwood extract (BWHE) to induce laminitis. Healthy horses (5-15 years old) were randomly assigned to 4 groups: 3 experi...
Effect of different penetration enhancers on diclofenac permeation across horse skin. Diclofenac is a hydrophilic non-steroidal anti-inflammatory drug widely used in humans and animals. Previous reports have shown that this compound has low percutaneous absorption in horses. The effect of five penetration enhancers (10% urea, 15% and 20% oleic acid and 5% and 10% d-limonene) on the percutaneous absorption of diclofenac diethylamine through horse skin was evaluated in vitro using Franz-type diffusion cells. All tested penetration enhancers induced a significant increase in diclofenac diethylamine permeation, with limonene showing the highest enhancing effect at the lowest concen...
Radiation therapy communication: equine hemangioma. A 13-month-old Standardbred Colt had a recurrent hemangioma at the level of the coronary band. Multiple excisions had led to a nonhealing skin and hoof defect. Using 14 MV electrons, a total dose of 36 Gy was administered, given as six fractions of 6 Gy twice a week. Wound healing by second intention was achieved over the next 4 months and the colt began race training 6 months after the end of therapy. Twenty months later the colt is sound and there is no evidence of tumor recurrence.
Sensitization of skin mast cells with IgE antibodies to Culicoides allergens occurs frequently in clinically healthy horses. IgE antibodies are mediators of mast cell degranulation during allergic diseases. The binding of IgE to its high-affinity IgE receptor on mast cell surfaces is called "sensitization" and precedes the development of clinical allergy. Previously, intradermal injection of anti-IgE or the anti-IgG(T) antibody CVS40 induced immediate skin reactions in horses. This suggested that both IgE and IgG(T) sensitize equine skin mast cells. Here, we investigated sensitization to allergen and with IgE or IgG(T) in clinically healthy horses of different age groups. In addition, immediate skin reactions to Cul...
Case report: tripelennamine in the treatment of skin disorders in horses. Presented here is a case r eport on a horse that is a part of the South Dakota State Univeristy equestrian team. The horse experienced an itchy skin allergy, as did other horses. It was successfully treated with compounded tripelennamine hydrochloride injection and diphenhydramine hydrochloride, hydrocortisone and tripelennamine hydrochloride topical gel.
Skin disorders in horses. Many skin disorders in horses share the same appearance-hair loss of various degrees, itchiness, lesions that may or may not be painful to the touch, oozing sores, or skin that is reddened, crusty, scaly, flaky, thickened or swollen- making diagnosis sometimes difficult. A horse owner's documentation of a horse's medical history, the history of the skin disorder, and the horse's environment assists veterinarians and compounding pharmacists in their diagnosis and treatment. This article discusses some of the common skin problems that affect horses, takes a look at causes, and provides a case re...
Effects of platelet-rich plasma gel on skin healing in surgical wound in horses. To establish a low-cost method to prepare platelet-rich plasma (PRP) and evaluates the potential of platelet derived factors to enhance wound healing in the surgical wounds in equine. Methods: To obtain a PRP gel, calcium gluconate and autologous thrombin were added to platelet-rich plasma. For the tests six saddle horses were used and two surgical incisions were made in each animal. Wounds were treated with PRP gel or untreated. Sequential wound biopsies collected at Treatment 1: at days 5 and 30 and Treatment 2: at days 15 and 45 post wounding permitted comparison of differentiation markers ...
Lack of detectable equine herpesviruses 1 and 2 in paraffin-embedded specimens of equine sarcoidosis. Equine sarcoidosis is a rare, multisystemic, noncaseating, granulomatous and lymphoplasmacytic disease of unknown etiology. A recent report described a horse with granulomatous skin disease displaying histologic, electron microscopic, and polymerase chain reaction (PCR) findings consistent with equine herpesvirus 2 (EHV-2). Objective: To investigate the presence of EHV-2 and equine herpesvirus 1 (EHV-1) in 8 horses with sarcoidosis. Methods: Eight horses with sarcoidosis, reported previously. Methods: Retrospective study. PCR assays of the tissues were performed to detect DNA associated with E...
Prevalence, number and morphological types of multinucleated histiocytic giant cells in equine inflammatory dermatoses: a retrospective light microscopic study of skin-biopsy specimens from 362 horses. Multinucleated histiocytic giant cells (MHGC) are seen frequently in skin-biopsy specimens from horses with inflammatory dermatoses. However, the prevalence, number and morphological types of these cells have not been reported. Objective: To determine the prevalence, number and morphological types of MHGC in equine inflammatory dermatoses, and the association of these cells with specific conditions. Methods: Skin-biopsy specimens from 335 horses with inflammatory dermatoses and from 27 horses with normal skin were evaluated for the prevalence, number and morphological types of MHGC. Results: T...
Dietetic effects of oral intervention with mare’s milk on the Severity Scoring of Atopic Dermatitis, on faecal microbiota and on immunological parameters in patients with atopic dermatitis. In a double-blind, placebo-controlled crossover trial, 23 patients consumed 250 ml mare's milk or placebo for 16 weeks. The aim was to examine the effects of mare's milk on the characteristics of atopic dermatitis (AD), on faecal microbiota and on clinical and immunological parameters. The intensity of AD was examined using the Severity Scoring of Atopic Dermatitis (SCORAD) index. During the mare's milk period, the mean SCORAD value of patients (n=23; 17 females, 6 males) decreased from 30.1 to 25.3 after 12 weeks (P<0.05) and to 26.7 after 16 weeks (P<0.1). In a subgroup (n=7) the SCORA...
Randomised controlled trial of the treatment of pastern dermatitis with a formulation containing kunzea oil. The efficacy of an ointment containing kunzea oil for the treatment of horses with localised acute or chronic pastern dermatitis was assessed. Thirty-seven horses were randomly allocated to treatment with an ointment containing either 20 per cent kunzea oil (test) or 2 per cent ketoconazole (control). Only 21 of the horses completed the study. The severity of the lesions was assessed before and after seven days of treatment. The kunzea oil formulation resulted in a significant decrease in the median total area of the lesions from 40 cm(2) (range 3 to 252 cm(2)) to 0 cm(2) (range 0 to 34 cm(2))...
Equine skin tumours in 20 horses resembling three variants of human melanocytic naevi. Melanocytic tumours are important in horses, especially grey horses. Intradermal common melanocytic naevi, cellular blue naevi and combined cellular blue naevi are subgroups of human melanocytic tumours, which have not been reported in horses. In this study, we describe 20 horses with skin tumours similar to these naevi of humans. These tumours represented individual skin masses in male and female horses of different breeds. Tumours resembling human intradermal common melanocytic naevi were noted in 12 horses aged between 2 and 17 years. Seven horses aged between 4 and 15 years developed cutan...
Activated platelet-derived growth factor beta receptor expression, PI3K-AKT pathway molecular analysis, and transforming signals in equine sarcoids. The equine sarcoid is the most common dermatologic neoplasm reported in horses. Bovine papillomavirus (BPV) types 1 and 2 are associated with sarcoids, in which the expression of the major transforming oncoprotein (E5) is often recorded. The transformation activity of the virus is due to the binding of the E5 to the platelet-derived growth factor beta receptor (PDGFbeta-r). In the present study, we show by Western blot in 4 sarcoid samples and 3 normal equine skin samples that the PDGFbeta-r is more phosphorylated in sarcoid tissue than in normal skin (P < .001). Furthermore, the physical i...
Complications of equine wound management and dermatologic surgery. Complications of wounds and cosmetic surgery can be accurately managed with a combination of timely surgical and medical intervention to ensure the best possible outcome. The lack of soft tissue protection and a large quantity of susceptible synovial, tendon, ligament, and neurovascular structures make early and meticulous evaluation of limb wounds critical. Skin grafting is usually used following a period of open wound management and after healthy granulation tissue formation. Penetrating wounds of the abdomen or thorax have a guarded prognosis resulting from the ensuing potential for infecti...
Cutaneous fungal granuloma in a horse. This case report describes a 4-year-old-horse with two cutaneous masses on the right crest of the neck. Biopsy revealed chronic nodular pyogranulomatous dermatitis and panniculitis. Giemsa and periodic acid-Schiff stains showed focal spherical, yeast-like organisms. A diagnosis of cutaneous fungal granuloma was made. The size of the masses decreased after oral treatment with fluconazole for 10 days combined with potassium iodide for 30 days, and the remaining masses were excised by laser. Lesions did not recur at the site. Fungal granuloma should be considered as a differential diagnosis in ho...
Influence of time of day on body temperature, heart rate, arterial pressure, and other biological variables in horses during incremental exercise. We examined the response to exercise of selected physiological variables in horses performing the identical routine for eight days, in the morning (a.m.) or in the afternoon (p.m.). Heart rate (HR), systolic and diastolic blood pressure (BP), and body temperature (BT) were all consistently greater in the p.m. For BP and BT, the absolute increase above the a.m. values was the same at rest and during exercise. For HR, the absolute increase was greater during exercise, but the percent increase was the same as during rest. During exercise, blood glucose decreased, while blood lactate and skin temp...
Quantitative and qualitative evaluation of dermal elastin of draught horses with chronic progressive lymphoedema. Chronic progressive lymphoedema (CPL) in horses, a disease of certain draught breeds, is associated with altered elastin metabolism. The characteristic lesions are seen in the skin of the lower (distal) limbs. This study was based on horses of susceptible breeds, with and without CPL, and on horses of a non-susceptible breed. Skin samples were obtained for examination from the neck (considered a non-affected region) and from the distal limb. The skin lesions were characterized histologically and the dermal elastic fibres were evaluated morphologically and quantitatively. In all horses the mean...
Assessing techniques for disinfecting sites for inserting intravenous catheters into the jugular veins of horses. The sites of insertion of catheters into the jugular veins of six horses were investigated to determine common isolates and to assess the effectiveness of two disinfection protocols with the hair coat left long, clipped or shaved. Skin commensals (Staphylococcus, Streptococcus and Micrococcus species) and environmental contaminants (Bacillus, Enterobacteriaceae, Aspergillus and Mucor species) were the microorganisms most frequently isolated. Chlorhexidine gluconate and povidone-iodine-based skin disinfection protocols resulted in significant reductions in the number of bacterial isolates from ...
Nucleotide structure and expression of equine pigment epithelium-derived factor during repair of experimentally induced wounds in horses. To clone full-length equine pigment epithelium-derived factor (PEDF) complementary DNA (cDNA) and to evaluate its temporal expression during repair of wounds in horses. Methods: 4 clinically normal 2-to 3-year-old Standardbred mares. Methods: Full-length equine PEDF cDNA was cloned by screening size-selected cDNA libraries derived from biopsy specimens obtained from the wound edge 7 days after experimental creation of a 6.25-cm(2) full-thickness wound in the skin of the lateral thoracic wall. Expression was evaluated in normal skin and in biopsy specimens obtained weekly from experimentally in...
Evaluation of four topical preparations for the treatment of cannon hyperkeratosis in a horse. The response to treatment with four topical preparations was evaluated in an 11-year-old Morgan horse mare with histologically confirmed quadrilateral cannon hyperkeratosis. Each limb was treated for 30 days with 0.1% tacrolimus ointment, 0.1% adapalene gel, 0.2% phytosphingosine spray or a water-based emollient. Response to treatment was evaluated both histologically and visually. A water-based emollient and 0.1% tacrolimus ointment produced encouraging clinical responses. Pre-treatment histopathology identified marked, mostly compact, hyperkeratosis and follicular hyperkeratosis, most promin...
Expression of platelet-derived growth factor-beta receptor and bovine papillomavirus E5 and E7 oncoproteins in equine sarcoid. Equine sarcoids are benign fibroblastic skin tumours that are recognized throughout the world. Infection with bovine papillomavirus (BPV) types 1 and 2 has been implicated as a major factor in disease development; however, the cellular mechanisms underlying fibroblast transformation remain poorly defined. The present study further characterizes aspects of the association with BPV in 15 equine sarcoids. BPV DNA was demonstrated in 12/15 tumours collected from different areas of Italy. Nine of these 12 tumours expressed the BPV oncoproteins E5 and E7, but these oncoproteins were not expressed by...
Generalized sarcoidosis in two horses. Equine sarcoidosis is a rare disorder usually characterized by exfoliative dermatitis, moderate to severe wasting, and sarcoidal granulomatous inflammation of multiple organ systems. It has an unknown aetiopathogenesis. The condition is not related to equine sarcoid. This case report describes generalized cutaneous and systemic sarcoidosis in an 11-year-old Trakehner mare (case A) and in a 7-year-old Dutch Warmblood gelding (case B). Case A was presented with cutaneous sarcoidosis on the head and body and was diagnosed on the basis of histological examination of skin. Case B presented with mul...
