Postmortem findings in four litters of dogs with familial canine dermatomyositis

Postmortem evaluations were performed on 20 juvenile to young adult collie and collie-Labrador retriever crossbred dogs with dermatomyositis and 10 neonatal collies. Cutaneous, muscular, and vascular lesions were present in the juvenile and adult dogs and were most severe in areas of the head and distal extremities. In more severely affected dogs, lesions were more generalized, including myositis of esophageal muscle and arteritis of skin, muscle, bladder, and spermatic cord. Although viruses were not isolated from muscle, crystalline viral-like structures were present in cytoplasm of endothelial cells within skeletal muscle. The dogs with dermatitis and myositis consistently had lymphoid hyperplasia, especially of peripheral lymph nodes. More severely affected dogs were smaller than less severely affected littermates, and the more severely affected males had reduced weight of testicles and prostate glands, compared with body weight. The reduced weight of genital organs correlated positively with reduced fertility. A few lymphoid aggregates were present in or around thyroid glands of 6 of the 20 dogs. There was no histologic evidence of glomerular disease in any of the dogs. The neonatal collies had no evidence of dermatomyositis.     

Intracellular calcium in canine muscle biopsies

Intracellular staining for calcium was studied in muscle biopsies from 15 dogs by the alizarin red S (ARS) stain. Rare positive fibres were present in normal muscle and in denervation atrophy. The percentage of positive fibres was slightly increased in polymyositis, dermatomyositis and canine temporal/masseter myositis and markedly increased in progressive muscular dystrophy. Calcium-positive fibres were usually so-called large-dark (hypercontracted) fibres or necrotic fibres, although there was occasional staining of normal and atrophied fibres. These results indicate the probable involvement of calcium in muscle injury in canine inflammatory myopathies and in canine muscular dystrophy. In addition, use of the ARS stain appears to be useful for detecting the earliest lesions of acute muscle fibre injury.     

Prospective study of familial canine dermatomyositis. Correlation of the severity of dermatomyositis and circulating immune complex levels.

Familial canine dermatomyositis in collie dogs is a newly recognized spontaneous disease that resembles dermatomyositis in children. A litter of 9 collie dogs was studied from birth to 7.5 months of age. The onset and severity of dermatitis and myositis correlated with elevated serum levels of circulating immune complexes (CICs) and IgG. The immunoglobulin component of the CICs consisted principally of IgG. All dogs developed elevated levels of CIC before or concurrent with the onset of dermatitis. Myositis developed later. The CIC tended to peak between 14-18 weeks of age in all dogs except the most severely affected dog, in which the CICs continued to increase to 238 micrograms/ml (controls 30 micrograms/ml) at 7 months of age. In the moderately affected dogs the CICs tended to stabilize at the levels reached at 14-18 weeks, and in the mildly affected dogs the CICs tended to decrease to normal levels after 14-18 weeks. Although the dogs had electromyographic and repetitive nerve stimulation abnormalities, the abnormalities did not correlate with severity of dermatomyositis or degree of elevation of CICs or IgG. Necropsy at 7.5 months of age revealed that all dogs had myositis and 8 of 9 had dermatitis. Except for 1 dog, the severity of dermatomyositis correlated positively with higher levels of CICs. A strong positive association between elevated levels of CICs and IgG, but not IgM or IgA, was generally present. Elevated levels of CICs appear to be involved in the mechanisms that control the development, severity, and progression of dermatomyositis in collie dogs.     

Histological and immunohistochemical study of clinically normal skin of Leishmania infantum-infected dogs

Skin lesions are the most usual manifestation of canine leishmaniosis. The aim of this study was to investigate the histological pattern and parasite load in clinically normal skin of Leishmania-infected dogs. Two groups of Leishmania-infected dogs were studied. Group A consisted of 15 symptomless animals which, although seronegative or only mildly seropositive, gave a positive polymerase chain reaction (PCR) for Leishmania in the skin. Group B consisted of 20 clinically affected dogs which were highly seropositive and PCR-positive. Biopsies of normal skin from all dogs were processed for routine histology and Leishmania immunohistochemistry. The study demonstrated microscopical lesions and the presence of parasites in the skin from dogs of group B, but not group A. The results cast doubt on the relevance of infected but symptomless dogs in the epidemiology of canine leishmaniosis. In contrast, however, the clinically normal skin of sick dogs harbours the parasite and probably plays a role in the transmission of leishmaniosis.     

Canine cutaneous epitheliotropic lymphoma (mycosis fungoides) is a proliferative disorder of CD8+ T cells.

Canine epitheliotropic lymphoma (mycosis fungoides [MF]) is a spontaneous neoplasm of skin and mucous membranes that occurs in old dogs (mean age 11 years) and has no breed predilection. The lesions evolve from a patch-plaque stage with prominent epitheliotropism into a tumor stage in which distant metastasis is observed. Unlike human MF, epitheliotropism of the lymphoid infiltrate is still prominent in tumor stage lesions. Tropism of the lymphoid infiltrate for adnexal structures, especially hair follicles and apocrine sweat glands, was marked in all clinical stages of canine MF. Twenty-three cases of MF were subjected to extensive immunophenotypic analysis in which reagents specific for canine leukocyte antigens and fresh frozen tissue sections of the canine lesions were used. Canine MF proved to be a T cell lymphoma in which the epitheliotropic lymphocytes consistently expressed CD3 (22 cases) and CD8 (19 cases); CD3+CD4-CD8- lymphocytes predominated in the remaining 4 cases. In this regard, canine MF clearly differed from human MF in which a CD4 immunophenotype predominates in the T cell infiltrate. Lack of expression of CD45RA by epitheliotropic T cells and intense expression of a beta 1 integrin (VLA-4-like) suggested that T cells in canine MF belonged to the memory subpopulation, as has been suggested for T cells in human MF. Pan-T cell antigen loss or discordant expression also proved useful as phenotypic indicators of neoplasia in canine MF. Loss of CD5 was observed in epitheliotropic T cells in 63% of cases. Discordance of neoplastic T cell Thy-1 expression was frequently observed between epithelial and dermal or submucosal compartments. We conclude that canine MF still represents a useful spontaneous animal disease model of human cutaneous T cell lymphoma, despite the immunophenotypic differences, which may reflect operational differences between human and canine skin-associated lymphoid tissue.     

Tuberculin-specific transfer factor in dogs.

The present study examined the specificity of guinea pig erythrocyte (E) and erythrocyte-antibody-complement (EAC) rosette formation assays with suspensions of canine peripheral blood lymphocytes. Neutrophils, monocytes, and lymphocytes bound EAC but not erythrocyte-antibody (EA) controls. Similarly, all three cell types formed rosettes with guinea pig E. Adherence of guinea pig E to these cells was apparently mediated by natural cytophilic antibodies present in the serum used in the suspension medium. The nonspecificity of the guinea pig E-rosette formation assay with canine lymphocytes renders the technique unreliable for the identification of thymus-derived lymphocytes in dogs.     

Sensitization of Naive Beagles by Intradermal Injection of an Ascaris Antigen: Induction of a Model of Skin Allergy

Ascaris suum-hypersensitive beagles represent a unique model of skin allergy. Despite its suitability, the need to test numerous dogs prior to the selection of natural positive responders causes many complications. We hypothesized that the model could be induced in adult beagles by primary sensitization. Ten dogs were included in an intradermal sensitization program using ascaris antigen and were thereafter tested for cutaneous reaction. After 2 weeks, 60% developed a positive reaction that lasted for months. We therefore present a straightforward method to establish the Ascaris canine model of allergy that will extend its availability for research in cutaneous allergy immunomodulation.     

Sensitization of naive beagles by intradermal injection of an ascaris antigen: induction of a model of skin allergy

Ascaris suum-hypersensitive beagles represent a unique model of skin allergy. Despite its suitability, the need to test numerous dogs prior to the selection of natural positive responders causes many complications. We hypothesized that the model could be induced in adult beagles by primary sensitization. Ten dogs were included in an intradermal sensitization program using ascaris antigen and were thereafter tested for cutaneous reaction. After 2 weeks, 60% developed a positive reaction that lasted for months. We therefore present a straightforward method to establish the Ascaris canine model of allergy that will extend its availability for research in cutaneous allergy immunomodulation.     

Detrusor myopathy in young beagle dogs

Hematoxylin and eosin-stained sections of urinary bladder were examined microscopically from 449 male and female beagle dogs after 2- to 4-week toxicology studies. Degenerative lesions (detrusor myopathy) of the urinary bladder muscular tunic were present in 59 of 449 (13%) dogs. Myopathic lesions consisted of focal to multifocal areas of smooth muscle fiber atrophy with cytoplasmic basophilia and vacuolation, individual cell necrosis, enlarged smooth muscle nuclei and nucleoli, and occasional mitotic figures. Adjacent areas of arteritis and periarteritis were present in 10 of 59 (17%) beagles with detrusor myopathy suggesting a possible ischemic pathogenesis of the smooth muscle lesions. There was no significant difference in prevalence of myopathy in beagles administered vehicle or various test compounds. Prior urinary catheterization procedures appeared to augment the prevalence of myopathy; some lesions were adjacent to minor, iatrogenically traumatized urinary bladder mucosa. Muscle lesions were not observed in urinary bladders from mongrel dogs, monkeys, cats, rats, or microswine. When compared to crossbred dogs and other laboratory species, the beagle dog thus appears to be sensitive to development of detrusor myopathy.     

Cutaneous cryptococcosis in a donkey

A 7-year-old indigenous male donkey presented with a 3-month history of non-healing ulcerated nodular lesions involving the skin and subcutaneous tissue of the ears. The affected ears were misshapen due to firm, small, often ulcerated nodules along with seropurulent discharge and some local. There was histopathologically granulomatous dermatitis composed of multinucleated giant cells, macrophages, lymphocytes, plasma cells, and eosinophils in the dermis. Numerous ovoid or spherical, yeast-like organisms in small clear halo or spaces were present both freely and in the cytoplasm of macrophages and giant cells. The capsule was stained by periodic acid schiff and Alcian blue stains. Based on lesion histopathology, it was diagnosed as cutaneous cryptococcosis. The following article documents previously unreported gross and histologic findings of cutaneous cryptococcosis in a donkey.     

Muscle lesions associated with dystrophin deficiency in neonatal golden retriever puppies

Golden retriever muscular dystrophy (GRMD), a degenerative myopathy due to the absence of dystrophin, is genetically homologous to human Duchenne muscular dystrophy (DMD). Spontaneous death of GRMD neonates within the first 2 weeks of life occurs frequently. This report describes the microscopical muscle lesions that developed in 12 GRMD puppies aged 1-8 days of age, and makes a comparison with three normal age-matched siblings and two older GRMD dogs. Immunohistochemical methods were used to confirm dystrophin deficiency in GRMD puppies. Muscle lesions were assessed on sections stained with haematoxylin-eosin-saffron, Gomori's trichrome and alizarin red S, and their severity was graded semi-quantitatively. Muscle fibre types were determined immunohistochemically on the basis of the pattern of expression of developmental, slow and fast isoforms of myosin. Muscle lesions in the GRMD puppies were characterized by massive necrosis, affecting most muscles of the proximal limbs, trunk and neck at birth. Lingual lesions began to develop in utero, and respiratory muscles underwent terminal diffuse necrosis resulting in death from acute respiratory failure. However, GRMD puppies do not invariably die in the neonatal period. Muscle in 2-month-old GRMD dogs showed signs of regeneration (immunohistochemical immaturity of muscle tissue), which suggested that all GRMD dogs suffer from massive post-natal myonecrosis, whether fatal or not. Muscle lesions in neonates consisted mainly of hyalinization, hypertrophy, calcification and necrosis, followed by regeneration. Such "phase I" lesions due to the absence of dystrophin are found in all species in which dystrophin deficiency has been described (human beings, dogs, cats and mice), whereas the endomysial fibrosis and myofibre atrophy found in 2-month-old GRMD dogs constituted "phase II" lesions, which are specific to GRMD and human DMD.     

Cutaneous histiocytoma in a heifer

A young Friesian heifer developed multiple skin nodules. Histologically, the tumours appeared similar to the canine cutaneous histiocytoma. Over the next few weeks, the tumours underwent regression. These findings are considered to be consistent with a case of hitherto unreported bovine cutaneous histiocytoma. The only previously reported cases have been in dogs.     

Lymphocytic insulitis in a juvenile dog with diabetes mellitus

Autoimmune diabetes has never been described in a juvenile dog, whereas serologica evidence has established its development in adult dogs. Diabetes mellitus was diagnosea in a 3-mo-old Donge de Bordeaux dog suffering from persistent hyperglycemia and concurrent insulinopenia. Histological analysis of the pancreas revealed in flammatory lesions in 40% of the islets of Lagerhans, with infiltration predominantly by T lymphocytes (more than 90%), either at the edge (peri-insulitis: 10%) or in the islets (insulitis: 30%). The remaining 60% of the islets showed a marked atrophy due to massive beta cell loss with no loss of alpha cells. This pattern is quite similar to that observed in humans in which a characteristic insulitis containing high numbers of T lymphocytes is found in 20% of the islets at diabetes diagnosis. By contrast, in rodent models, nearly 70% of the islets of langerhans show inflamation at diagnosis and macrophages and dendritic cells predominate in the inflamatory lesions. This is the first report of lymphocytic insulitis in a juvenile dog exhibiting diabetes mellitus. Our observations suggest an autoimmune origin for the disease in this dog that is similar to human type 1 diabetes mellitus, for which there is no accurate spontaneous large animal model. These authors contributed equally to this work     

Juvenile hyaline fibromatosis: two new patients and review of the literature

We report on a sister and a brother (born to normal consanguineous parents) with joint contractures and osteolytic lesions of bones. The sister had also gingival hyperplasia and skin lesions consisting of multiple tumors of the face, nose, palate, ears, and neck. Histologic examination showed findings of juvenile hyaline fibromatosis. The literature is reviewed, and 15 cases already reported are summarized.     

Development of a real-time PCR to detect <Emphasis Type="Italic">Demodex canis</Emphasis> DNA in different tissue samples

The present study reports the development of a real-time polymerase chain reaction (PCR) to detect Demodex canis DNA on different tissue samples. The technique amplifies a 166 bp of D. canis chitin synthase gene (AB 080667) and it has been successfully tested on hairs extracted with their roots and on formalin-fixed paraffin embedded skin biopsies. The real-time PCR amplified on the hairs of all 14 dogs with a firm diagnosis of demodicosis and consistently failed to amplify on negative controls. Eleven of 12 skin biopsies with a morphologic diagnosis of canine demodicosis were also positive. Sampling hairs on two skin points (lateral face and interdigital skin), D. canis DNA was detected on nine of 51 healthy dogs (17.6%) a much higher percentage than previously reported with microscopic studies. Furthermore, it is foreseen that if the number of samples were increased, the percentage of positive dogs would probably also grow. Moreover, in four of the six dogs with demodicosis, the samples taken from non-lesioned skin were positive. This finding, if confirmed in further studies, suggests that demodicosis is a generalized phenomenon in canine skin, due to proliferation of local mite populations, even though macroscopic lesions only appear in certain areas. The real-time PCR technique to detect D. canis DNA described in this work is a useful tool to advance our understanding of canine demodicosis.     

Skeletal muscle major histocompatibility complex class I and II expression differences in adult and juvenile dermatomyositis

OBJECTIVE:

To analyze major histocompatibility complex expression in the muscle fibers of juvenile and adult dermatomyositis.

METHOD:

In total, 28 untreated adult dermatomyositis patients, 28 juvenile dermatomyositis patients (Bohan and Peter''s criteria) and a control group consisting of four dystrophic and five Pompe''s disease patients were analyzed. Routine histological and immunohistochemical (major histocompatibility complex I and II, StreptoABComplex/HRP, Dakopatts) analyses were performed on serial frozen muscle sections. Inflammatory cells, fiber damage, perifascicular atrophy and increased connective tissue were analyzed relative to the expression of major histocompatibility complexes I and II, which were assessed as negatively or positively stained fibers in 10 fields (200X).

RESULTS:

The mean ages at disease onset were 42.0±15.9 and 7.3±3.4 years in adult and juvenile dermatomyositis, respectively, and the symptom durations before muscle biopsy were similar in both groups. No significant differences were observed regarding gender, ethnicity and frequency of organ involvement, except for higher creatine kinase and lactate dehydrogenase levels in adult dermatomyositis (p<0.050). Moreover, a significantly higher frequency of major histocompatibility complex I (96.4% vs. 50.0%, p<0.001) compared with major histocompatibility complex II expression (14.3% vs. 53.6%, p = 0.004) was observed in juvenile dermatomyositis. Fiber damage (p = 0.006) and increased connective tissue (p<0.001) were significantly higher in adult dermatomyositis compared with the presence of perifascicular atrophy (p<0.001). The results of the histochemical and histological data did not correlate with the demographic data or with the clinical and laboratory features.

CONCLUSION:

The overexpression of major histocompatibility complex I was an important finding for the diagnosis of both groups, particularly for juvenile dermatomyositis, whereas there was lower levels of expression of major histocompatibility complex II than major histocompatibility complex I. This finding was particularly apparent in juvenile dermatomyositis.     

Avian pox infection in Spanish Imperial eagles (Aquila adalberti)

A cutaneous lesion, previously known as "warts", affecting the featherless parts of face and legs has long been recognized in juvenile Spanish Imperial eagles (Aquila adalberti). This paper describes the presentation, microbiological, histopathological, and electron microscopic findings of lesions and diagnosis of poxvirus infection in nine juveniles. Lesions consisted of single or multiple nodules with a crust and surrounded by skin swelling. Seventy-eight percent of the swabs taken from lesions yielded bacterial growth, with Escherichia coli being the most common bacterium isolated. Histopathology revealed typical pox lesions in all cases. Histopathological changes found consisted of proliferative epithelium, with ballooning degeneration of keratinocytes and lymphocyte infiltrates extending into underlying dermis. Avianpox virus was confirmed by the presence of eosinophilic intracytoplasmatic inclusion bodies in the affected cells on light microscopy, and diagnosis confirmation was performed by electron microscopy of biopsies from all nine eagles.     

Pathology of acute graft-versus-host disease in the dog. An autopsy study of ninety-five dogs.

The morphology of graft-versus-host disease (GVHD) in canine radiation chimeras was studied by examination of autopsy tissue from 95 dogs including: 1) 13 healthy, untreated dogs; 2) 9 dogs given 1200 R total body irradiation and no marrow infusion; 3) 17 dogs given 1200 R and autologous marrow infusion; 4) 25 dogs given 1200 R and hemopoietic cells from dog-leukocyte-antigen (DLA)--identical littermates; and 5) 31 dogs given 1200 R and nonidentical DLA hemopoietic cells. Some of the dogs in Groups 3--5 received a postgrafting methotrexate (MTX) regimen of 0.25--0.5 mg/kg body weight on Days 1, 3, 6, and 11 and once weekly until Day 102. Prominent lesions were found in the small and large intestines, skin, and liver of dogs with allogeneic grafts. Skin lesions consisted of lymphocytic infiltrates of epidermis with necrosis of basal epidermal cells progressing to denudation. Gut lesions consisted of mucosal destruction progressing from crypt abscess formation to denudation. Liver lesions consisted of portal triaditis, plasmacytic and lymphocytic infiltrates, necorsis and atypia of small bile ducts, and scattered individual hepatocyte necrosis. These lesions were differentiated from changes caused by irradiation and MTX and were deemed characteristic of GVHD. The overall severity of GVHD lesions was less in the identical DLA group than in the nonidentical DLA group, and also less in dogs treated with MTX than in those not given MTX. The degree of lymphoid depletion in the lymph nodes, spleen, and intestinal lymphoid tissue was very similar in dogs with autologous and allogeneic grafts at comparable survival times. No specific evidence of pancreatic or renal involvement in GVHD was discovered.     

Polymyositis following Vogt-Koyanagi-Harada-like syndrome in a Jack Russell terrier

A male Jack Russell terrier developed bilateral uveitis and glaucoma at 1 year of age. Since the ocular disease was painful and unresponsive to treatment, both globes were enucleated. Microscopical evaluation of one enucleated globe revealed panuveitis, with pigment dispersion and phagocytosis consistent with the ocular lesions of canine Vogt-Koyanagi-Harada (VKH)-like syndrome. Three years later the dog was represented with severe muscle disease and skin lesions. Due to rapid clinical deterioration the dog was humanely destroyed. Necropsy examination revealed lichenoid interface inflammation in the skin and mucous membranes, with pigmentary incontinence consistent with VKH-like syndrome and lymphocytic and histiocytic polymyositis with marked muscle atrophy. Canine VKH-like syndrome is an autoimmune disease that targets melanocyte antigens. Some human patients with VKH disease develop additional autoimmune diseases. To our knowledge this is the first reported case of polymyositis subsequent to VKH-like disease in a dog. In addition, VKH-like disease has not been previously reported in a Jack Russell terrier.     

Patch test responses to Malassezia pachydermatis in healthy dogs.

The effects of the patch test application of Malassezia pachydermatis extracts to normal canine skin were evaluated in eight healthy beagle dogs. Antigens (4 and 0.4 mg/ml) and saline controls were applied for 48 h using filter paper discs in Finn chambers. At the first test, two dogs showed patch test reactivity 20 min and 24 h after patch removal. Four out of six dogs that did not react to the first patch test showed reactivity when re-tested on day 8. Two remaining dogs were patch tested for a third time on day 15, after 7 days of cutaneous challenge with suspensions of M. pachydermatis cells, but failed to display reactivity. Positive patch test reactions were characterized histologically by mild epidermal hyperplasia, superficial dermal oedema and mild to moderate perivascular, periadnexal and interstitial infiltrates of neutrophils and CD3+ lymphocytes. Four dogs showed delayed intradermal test reactivity to M. pachydermatis antigens but intradermal and patch test reactivity did not correlate. This study indicates that patch test reactivity to M. pachydermatis antigen occurs in some healthy dogs exposed to the yeast, or may develop after a short period of antigen exposure. Further studies of patch test reactivity are warranted in dogs with disease associated with this cutaneous yeast.