Cutaneous habronemosis in horses: First molecular characterization of Habronema muscae in Israel

Draschia megastoma, Habronema microstoma, and Habronema muscae are the etiological agents of cutaneous habronemosis, commonly known as summer sores, an inflammatory cutaneous and ocular parasitic disease of horses and other equids transmitted by flies. Here, we describe a cluster of cutaneous habronemosis in five horses that showed single or multiple typical cutaneous ulcerative wounds located on the face, lower forelegs or hindquarters in Israel with the presence of typical "sulphur granules." All affected animals were confirmed by histopathological and/or molecular methods to be infected by H. muscae. This constitutes the first report of cutaneous habronemosis in Israel in which the causative nematode, H. muscae, was identified by molecular means. Cutaneous habronemosis should be considered as a differential diagnosis in equids with cutaneous ulcerative lesions during the summer months, especially when affected animals are refractive to antibiotic treatment alone.     

Molecular cross-sectional survey of gastric habronemosis in horses

Gastric habronemosis of horses caused by Habronema microstoma and Habronema muscae (Nematoda, Spirurida) is characterized by catarrhal gastritis, diarrhoea, progressive weight loss and ulcers. Despite its importance in the equine industry and in clinical practice, knowledge of the epidemiology of this infection is still incomplete as diagnosis in live animals is challenging. A two-step semi-nested PCR assay using ribosomal DNA (rDNA) markers has recently been used for the molecular diagnosis in vivo of gastric habronemosis based on the detection of H. microstoma and/or H. muscae DNA in equine faeces. To evaluate the field efficacy of this assay, a molecular epidemiological survey was carried out on equid gastric habronemosis in central Italy. One hundred and fifty-three individual faecal samples were collected from live native horses and subjected to both coprological examination and the two-step semi-nested PCR. When flotation procedures were performed no horse tested positive for Habronema spp. larvated eggs while 96 animals (61.2%) were positive for other endoparasites (i.e. strongyles, oxyurids, ascarids). Two-step semi-nested PCR detected 86 samples (53.6%) that were positive for H. microstoma and/or H. muscae DNA. H. microstoma prevalences showed statistically significant differences; the highest prevalence was observed in horses infected by other gastrointestinal parasites and concomitantly by H. muscae. No statistical differences were found between the prevalence of Habronema spp. infection and sex, age, breeding management, and antiparasitic treatments. This field survey provided further information on habronemosis and its epidemiology.     

Equine Sarcoid Associated with Cutaneous Habronemosis

Equine sarcoids are benign fibroblastic skin tumors affecting equids worldwide. Infection with bovine papillomavirus types 1 and 2 has been implicated as a major fact in the disease development; however, the cellular mechanisms underlying fibroblast transformation are still largely unknown. In the present study, a diagnosis of sarcoid was histologically assessed along with eosinophilic dermatitis. The sarcoid lesion expressed the viral oncoproteins E5 and E2, suggesting a causative role of the virus and its replication. Ribosomal DNA of the nematode Habronema muscae was also revealed in the lesion. This is the first report to describe and discuss an association of cutaneous habronemosis with equine sarcoid.     

Successful surgical management of eosinophilic granuloma on the urethral process of a gelding associated with Habronema spp. infection

Habronemiasis, otherwise known as summer sores, is a parasitic disease of horses, donkeys and other equids, commonly encountered in subtropical and tropical regions. It occurs as a result of nematode infestation of the skin and typically manifests as ulcerative granulating lesions or masses. Habronema muscae, Habronema microstoma and Draschia megastoma are the usual invaders, usually transmitted by house flies, face flies and stable flies. In this case report, an eosinophilic granuloma on the urethral process of a 15-year-old gelding is presented, followed by successful surgical excision without further medical treatment. To the authors’ knowledge, equine eosinophilic granuloma on the urethral process associated with habronemiasis has not previously been documented in southern Europe and should be considered as a potential differential diagnosis for penile masses.     

Nodular diseases

The development of a nodule is a fairly common reaction pattern in the skin and subcutaneous tissues of the horse. In many such nodules, the inciting aetiologic agent or antigen is unknown, but in some equine cases there is significant evidence for insect bite origin. The pathogenesis of some equine nodular diseases appears to involve marked collagen degeneration which varies from hyalinization to lysis and can become mineralized. The exact role the lytic collagen has in the pathogenesis of these lesions is still unknown. Vascular changes may be present in some entities. Other nodules may be caused by or complicated by the larva of Habronema spp. The clinical or histological entities outlined in this section include the collagenolytic granuloma, axillary nodular necrosis, unilateral papular dermatosis and cutaneous habronemiasis.     

Mycologic disorders of the skin

Cutaneous tissue can become infected when fungal organisms contaminate or colonize the epidermal surface or hair follicles. The skin can be a portal of entry for fungal infection when the epithelial barrier is breached or it can be a site for disseminated, systemic fungal disease. The two most common cutaneous fungal infections in small animals are dermatophytosis and Malassezia dermatitis. Dermatophytosis is a superficial cutaneous infection with one or more of the fungal species in the keratinophilic genera Microsporum, Trichophyton, or Epidermophyton. Malassezia pachydermatis is a nonlipid dependent fungal species that is a normal commensal inhabitant of the skin and external ear canal in dogs and cats. Malassezia pachydermatis is the most common cause of Malassezia dermatitis. The diagnosis and treatment of these cutaneous fungal infections will be discussed.     

A comparative review of cutaneous pH

Abstract This review describes the role of pH in cutaneous structure and function. We first describe the molecules that contribute to the acidity or alkalinity of the skin. Next, differences in cutaneous pH among species, among individuals of the same species and within individuals are described. The potential functions of cutaneous pH in normal and diseased skin are analysed. For example, cutaneous pH has a role in the selection and maintenance of the normal cutaneous microbiota. In addition, cutaneous acidity may protect the skin against infection by microbes. Finally, there is evidence that a cutaneous pH gradient activates pH-dependent enzymes involved in the process of keratinization.     

Detection of feline herpes virus 1 via polymerase chain reaction and immunohistochemistry in cats with ulcerative facial dermatitis, eosinophilic granuloma complex reaction patterns and mosquito bite hypersensitivity

Ulcerative dermatitis caused by feline herpes virus 1 (FHV-1) is an uncommon disease characterized by cutaneous ulcers secondary to epidermal, adnexal and dermal necrosis. Differential diagnoses for FHV-1 lesions include, but are not limited to, mosquito bite hypersensitivity and eosinophilic granuloma complex. Histopathological diagnosis of FHV-1 dermatitis is based on the detection of the intranuclear inclusion bodies. In cases where intranuclear inclusions are missing but clinical and histological findings are compatible with FHV-1 dermatitis, immunohistochemistry (IHC) and PCRs have been used. In this retrospective study, we evaluated the presence of FHV-1 by IHC and PCR in skin biopsies and compared the results of the two tests. Sixty-four skin biopsy specimens from cats with compatible lesions were reviewed and tested via PCR and IHC for evidence of FHV-1. Polymerase chain reaction was positive in 12 of 64 biopsies; PCR and IHC were positive only in two of 64 biopsies, and these cases were considered true positive cases. The higher number of PCR-positive cases was possibly attributed to amplification of viral DNA from a live attenuated vaccination, but a previous FHV-1 infection with subsequent amplification of latently inserted FHV-1 could not be excluded. If clinical signs and histopathology suggest FHV-1 infection in the absence of typical inclusion bodies, IHC is the preferred diagnostic test; PCR may be useful for initial screening, but due to false positives is not sufficient for a definitive diagnosis.     

The role of Hydrotaea irritans in the transmission of summer mastitis

A series of experiments to investigate the possible role of the sheep head fly, Hydrotaea irritans, in the transmission of summer mastitis is reported. These showed that the pathogens Actinomyces pyogenes and Peptococcus indolicus may be harboured in the gut of the fly for up to 96 h following a contaminated meal; A. pyogenes survived on the surface of the fly for a similar period. H. irritans fed on the pathogens can contaminate a subsequent meal by regurgitation. However, no infections resulted from repeated exposure of the teats of heifers or cows to H. irritans fed on blood containing A. pyogenes and P. indolicus or on pus from a case of summer mastitis. In these experiments the frequency of feeding of the flies on the teat was high but subsequent bacterial contamination of the teat skin was low. Artificial contamination of the teat skin with greater than 10(6) cfu A. pyogenes led to a low incidence of mastitis even in the absence of cutaneous damage. Repeated applications of lower doses (less than 10(4) cfu) did not produce infection.     

Amplification of papillomaviral DNA sequences from a high proportion of feline cutaneous in situ and invasive squamous cell carcinomas using a nested polymerase chain reaction

Squamous cell carcinomas (SCCs) are common skin tumours of cats. Previous studies have suggested that papillomaviral (PV) DNA is detectible within some feline SCCs. A PV DNA sequence has been previously amplified from five feline bowenoid in situ carcinomas (BISCs). Primers specific for this sequence were used in a nested polymerase chain reaction to compare PV detection rates in SCCs to rates within non-SCC skin lesions. Papillomaviral DNA was amplified from 20 of 20 BISC, 17 of 20 invasive SCC and 3 of 17 non-SCC controls. The rate of PV amplification from feline cutaneous SCCs was significantly higher than from non-SCC lesions. These results confirm that feline cutaneous SCCs are associated with PV infection. In humans, there is evidence that PVs promote SCC development within sun-exposed skin. The demonstrated association between PVs and feline cutaneous SCCs suggests, but does not prove, that PVs may also promote feline SCC development. If PVs are oncogenic in cats, prevention of PV infection may reduce feline cutaneous SCC development. To the authors' knowledge, this is the first time that PV DNA has been amplified from a non-SCC sample of feline skin.     

Cutaneous neosporosis in two adult dogs on chronic immunosuppressive therapy.

Antemortem diagnosis of generalized ulcerative and pyogranulomatous dermatitis with numerous intralesional tachyzoites was made from skin biopsy specimens from 2 adult dogs on chronic immunosuppressive therapy. A 9-year-old Italian Greyhound was on long-term corticosteroid therapy for the treatment of a lupus-like systemic autoimmune disorder, and a 7-year-old Labrador Retriever had received several months of chemotherapy for lymphosarcoma. The tachyzoites were identified as Neospora caninum by immunoperoxidase immunohistochemistry. Both dogs were treated with clindamycin. Lesions in the Greyhound resolved; however, the Labrador Retriever was euthanized because of evidence of neuromuscular disease, despite improvement of the skin lesions. These 2 cases indicate that cutaneous neosporosis can occur in adult dogs on chronic immunosuppressive therapy. The disease may result from reactivation of a congenital infection and/or a recently acquired primary infection.     

Papular cutaneous lesions in a cat associated with feline infectious peritonitis

A 7-month-old-intact male domestic shorthair cat was presented with fever, anterior uveitis in the right eye and respiratory distress when handled. These signs along with mild changes in serum protein levels and the exclusion of other potential causes were suggestive of feline infectious peritonitis (FIP). As the disease progressed, more clinical signs consistent with FIP, including renal involvement and later pleural effusion, became evident. Non-pruritic cutaneous lesions, characterized by slightly raised intradermal papules over the dorsal neck and over both lateral thoracic walls, were recognized at the end stage of the disease. The identification of papules in well-haired skin was difficult, and clipping of the fur facilitated their detection. Definitive diagnosis of FIP was made by histopathology and by immunohistochemical demonstration of coronavirus antigen in macrophages within kidney and skin lesions. The case was classified as a mixed form of FIP. Recognition of associated cutaneous lesions may facilitate a diagnosis of FIP in suspicious cases.     

Spotted fever group rickettsiae: a brief review and a Canadian perspective

Spotted fever group rickettsioses (SFGR) are infections caused by established and emerging human pathogens worldwide. These rickettsial agents are transmitted to humans via arthropods and may result in mild to severe and potentially fatal diseases. Spotted fever group rickettsioses are characterized by similar clinical features, including fever, rash, headache and myalgias, with the development of an inoculation eschar in many, but not all cases. Endemic rickettsial infections do occur but are infrequent in Canada, in contrast to the United States, where these infections are far more prevalent. Travel-associated rickettsioses, however, are being diagnosed with increasing frequency in Canadian travellers returning from international trips abroad, in particular in travellers returning from Africa. The diagnosis of rickettsial infections can be challenging owing to the non-specific nature of the clinical symptoms and the requirement for specialized testing. Serology cannot distinguish between the approximately 20 spotted fever group rickettsial species currently known or suspected to be capable of causing human infection. Molecular testing is required to determine the rickettsial species responsible for infection, but requires greater effort on the part of the clinician to collect appropriate samples, including cutaneous skin swabs from under the eschar or skin punch biopsies of the eschar or rash. Infections with spotted fever group rickettsiae likely occur more commonly than currently recognized and should be considered in patients with appropriate symptoms and exposure histories.     

Eleven cases of vesicular cutaneous lupus erythematosus in Shetland sheepdogs and rough collies: clinical management and prognosis

Abstract   A cutaneous ulcerative disease is recognized to affect the adult Shetland sheepdog and rough collie. This has a distinct clinical and histological appearance consistent with a vesicular variant of cutaneous lupus erythematosus (VCLE). Retrospective information on the clinical outcome and response to therapy was collected from 11 cases of histologically confirmed VCLE. In 8/11 dogs the onset of disease was in the summer; in three dogs recrudescence occurred in subsequent summers. In eight dogs the skin disease was judged to be 75–100% controlled with therapy after a minimum follow-up of 9 months. Successful treatment in seven of these cases comprised immunosuppressive doses of oral glucocorticoids, alone (one dog), in combination with azathioprine (five dogs) and doxycycline (one dog). One case responded to topical fluocinolone. Three dogs were euthanased for reasons directly related to the disease, one prior to initiating any therapy. Vesicular cutaneous lupus erythematosus in the rough collie and Shetland sheepdog can be a debilitating skin disease which is best managed with aggressive immunosuppressive therapy. Sun avoidance or the use of sunscreens is an important additional management recommendation.     

Staphylococcal skin disease in livestock

This review covers cutaneous manifestations of staphylococcal infection in livestock species. CATTLE: In cattle, staphylococcal infections may present as folliculitis or as impetigo. Both may present as mild forms of a group of conditions loosely termed udder dermatitis, which has various clinical presentations and does not always involve staphylococci. GOATS: In goats, staphylococcal infection may be secondary to chorioptic mange or contagious pustular dermatitis (parapox virus infection). While Staphylococcus aureus is usually implicated, infection with Staphylococcus chromogenes and Staphylococcus hyicus have also been reported. SHEEP: Ovine staphylococcal dermatitis typically involves the head. Trauma due to the close contact of heads over feeding troughs and abrasive plants at pasture may be predisposing factors. PIGS: In pigs, the most common cause of staphylococcal skin disease is S. hyicus, although other bacteria, including Staphylococcus sciuri, Staphylococcus chromogenes and meticillin-resistant S. aureus (MRSA), have also been isolated from some cases of greasy pig disease (exudative epidermitis). DIAGNOSIS: Routine culture methods are increasingly supplemented by molecular methods to characterize staphylococci. MANAGEMENT: As commensal bacteria, staphylococcal skin infection is presumed to develop because of predisposing factors. While topical and systemic therapies can be effective, it is important to control for predisposing factors so that recurrences can be prevented. LIVESTOCK-ASSOCIATED MRSA: In recent years, MRSA strains have emerged, particularly in pigs and cattle. While they rarely cause skin disease, they do pose a significant concern for public health authorities. Studies on livestock-associated MRSA may help to progress our understanding of staphylococci in livestock, especially how they spread between animals and humans.     

Identification of rickettsiae in cutaneous biopsy specimens from dogs with experimental Rocky Mountain spotted fever

Direct immunofluorescence reaction for Rickettsia rickettsii was performed on formalin-fixed, paraffin-embedded cutaneous biopsy specimens collected from dogs with experimental Rocky Mountain spotted fever (RMSF). A technique of trypsin digestion of deparaffinized, rehydrated sections was successful in demonstrating discrete, immunofluorescent organisms in endothelia and adjacent vessel walls in the dermis. R rickettsii was identified only in grossly evident dermal lesions (macular rash or oral vesicles) and was not apparent in randomly collected biopsy specimens from clinically normal inguinal skin. These results suggest that clinical application of this technique for diagnosis of RMSF may be limited in dogs without cutaneous lesions.     

Evaluation of a novel nested PCR for the routine diagnosis of feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV)

Laboratory diagnosis of feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) usually involves both viruses, as the clinical signs are similar and coinfection may occur. Serological methods may not represent an accurate diagnosis: maternal antibodies or cross-reactions may give false positive results to FIV, and false negative results may occur in latent FeLV status, or in certain FIV infection stages. A nested polymerase chain reaction (PCR) technique was designed to detect FeLV, FIV and feline endogenous retrovirus simultaneously. The detection of endogenous sequences was considered indicative of successful DNA extraction. The technique was used to diagnose FIV and FeLV in the blood cells of 179 cats. The kappa value with the serological data was 0.69 for FeLV and 0.87 for FIV. The joint detection of FeLV and FIV by this novel nested PCR is sensitive, specific, fast and convenient, and its applicability for clinical diagnosis is promising, as the direct evidence of the presence of the virus is more realistic than the indirect data provided by the serological detection.     

Infection of the equine population by Leishmania parasites

Infection of equids by Leishmania (L.) parasites was previously described in both the Old and New World, particularly in Central and South America. Equine cutaneous leishmaniasis (CL) is caused by the Leishmania species, L. Viannia (V.) braziliensis and L. infantum, previously identified in humans and other parasite hosts living in the same geographic endemic areas. Sporadic autochthonous clinical cases, with no travel history, were documented in several countries including Germany, Portugal, Spain, Texas and Brazil; L. infantum and L. (Mundinia) martiniquensis were the infectious species. Prevalence of subclinical infections is extremely low and CL is observed in only a small proportion of infected animals with the appearance of single or multiple cutaneous lesions located on the head, external ear, scrotum, legs and the neck. To date, there has been no report of visceral abnormalities. However, the mild clinical profile of the disease and its spontaneous regression may indicate that skin lesions related to Leishmania infection is underdiagnosed. Importantly, although the prevalence of Leishmania infections in the equine population is low, a risk may rise from its potential involvement in the parasite transmission cycles as a source of infection for phlebotomine vectors and susceptible mammalian hosts. This review article summarises our current knowledge of the epidemiology, clinical presentation and diagnosis of Leishmania-infected equids.     

Comparison of pulse administration versus once daily administration of itraconazole for the treatment of Malassezia pachydermatis dermatitis and otitis in dogs

OBJECTIVE To compare clinical efficacy of pulse administration with itraconazole versus once daily administration for the treatment of cutaneous and otic M pachydermatis infection in dogs. DESIGN: Randomized controlled trial. ANIMALS: 20 dogs. PROCEDURE: Dogs were treated with itraconazole orally (n = 10/group), using a pulse administration regimen (5 mg/kg [2.3 mg/lb], PO, q 24 h for 2 consecutive days per week for 3 weeks) or once daily administration (5 mg/kg, PO, q 24 h for 21 days). No other treatment was permitted. On days 0 and 21, clinical severity of cutaneous and otic disease was assessed, and samples were collected for cytologic examination and yeast culture. Cytology (sum of the mean number of yeast organisms per oil immersion field for affected sites) and culture (mean of the score for extent of yeast growth for samples from affected sites) scores were calculated. RESULTS: For dogs in both treatment groups, clinical severity of cutaneous and otic disease was significantly decreased by day 21, but decrease in severity was not significantly different between groups. Similarly, skin cytology, skin culture, and ear culture scores were significantly decreased on day 21, compared with day 0, for both groups, but decreases were not significantly different between groups except that dogs in the pulse administration group had a significantly greater decrease in ear culture scores than did dogs in the daily administration group. However, when cytology scores only for ear samples were analyzed, day 21 score was not significantly decreased, compared with day 0 score, for either group. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that both pulse administration and once daily administration of itraconazole were efficacious in the treatment of M pachydermatis cutaneous infection in dogs. However, adjunctive treatment may be needed in dogs with M pachydermatis otitis.