K. Paige Carmichael

Immunohistochemical Diagnosis of Chronic Wasting Disease in Preclinically Affected Elk from a Captive Herd

An immunohistochemical (IHC) method was used to test brain tissues from 17 elk in a captive herd in which chronic wasting disease (CWD) had previously occurred. The IHC technique detects the protease-resistant prion protein (PrP-res), which is considered a disease-specific marker for transmissible spongiform encephalopathies (TSE), regardless of the species affected. Of the 17 elk tested, 10 were positive by IHC. Only 2 of these 10 animals had shown clinical signs and histologic lesions of CWD, and an additional animal had histologic lesions only. The most consistently IHC-positive tissue was medulla oblongata, especially the obex. These results show that the PrP-res IHC test on brain tissue, specifically medulla oblongata at the obex, should be considered an essential component of any surveillance study intended to determine the incidence of CWD in captive or free-ranging cervids.

Variation among pathologists in histologic grading of canine cutaneous mast cell tumors.

Ten veterinary pathologists at 1 veterinary institution independently assigned histologic grades to the same 60 canine cutaneous mast cell tumors (MCTs). There was significant variation among pathologists in grading the MCTs (P < 0.001). The probability of assigning a low grade was significantly higher for the pathologists in this study who use a published reference for histologic grading of canine cutaneous MCTs that allows subcutaneous MCTs or MCTs with mitotic figures to be included in the low-grade category (P < 0.0001 and P < 0.0001, respectively).

Sulfamidase deficiency in a family of Dachshunds: a canine model of mucopolysaccharidosis IIIA (Sanfilippo A).

Mucopolysaccharidosis IIIA (MPS IIIA or Sanfilippo A, McKusick 25290) was diagnosed in two adult wire-haired Dachshund littermates. Clinical and pathologic features paralleled the human disorder; both dogs exhibited progressive neurologic disease without apparent somatic involvement. Pelvic limb ataxia was observed when the dogs were 3 y old and progressed gradually within 1-2 y to severe generalized spinocerebellar ataxia. Mentation remained normal throughout the course of the disease. A mucopolysaccharide storage disorder was indicated in both dogs by positive toluidine blue spot tests of urine. The diagnosis of MPS IIIA was confirmed by documentation of urinary excretion and tissue accumulation of heparan sulfate and decreased sulfamidase activity in fibroblasts and hepatic tissue. Mild cerebral cortical atrophy and dilation of the lateral ventricles were grossly evident in both dogs. Light microscopically, fibroblasts, hepatocytes, and renal tubular epithelial cells were vacuolated. Within the nervous system, cerebellar Purkinje cells, neurons of brainstem nuclei, ventral and dorsal horns, and dorsal ganglia were distended with brightly autofluorescent, periodic acid-Schiff-positive, sudanophilic material. Ultrastructurally, visceral storage presented as membrane-bound vacuoles with finely granular, variably electron-lucent contents. Neuronal storage appeared as membranous concentric whorls, lamellated parallel membrane stacks, or electron-dense lipid-like globules. This represents the first reported animal disease homolog of the human Sanfilippo A syndrome.

Neuroaxonal dystrophy in a group of related cats.

A syndrome resembling previously described feline hereditary neuroaxonal dystrophy (FHND) was diagnosed in a litter of cats. The disorder was characterized by a sudden onset of hind limb ataxia that slowly progressed to hind limb paresis and paralysis. The cats were between 6 and 9 months old when clinical signs were first noted. Histologically, there was marked ballooning of axonal processes, with spheroid formation and vacuolation in specific regions of the brain and spinal cord. Some dystrophic axons contained a central periodic acid-Schiff (PAS)-positive core. Neuronal loss and gliosis were seen in certain brain stem nuclei, spinal cord nuclei, and the cerebellum. Ultrastructurally, there was hypomyelination and dysmyelination of affected axons. The PAS-positive core in dystrophic axons corresponded ultrastructurally with accumulations of electrondense, flocculent, amorphous material. In addition, these axons contained membrane-bound osmiophilic bodies and large nonmembrane-bound vacuoles. The syndrome in this report differs from the previously described FHND in that no inner ear involvement was seen and onset of clinical signs occurred at a later age. In addition, although some of the affected cats did have diluted coat colors, abnormal coat color was not always associated with clinical disease. This disease is similar to juvenile neuroaxonal dystrophy in children and to neuroaxonal dystrophies described in horses, dogs, cattle, and sheep.

Characterization of cytokines associated with Th17 cells in the eyes of horses with recurrent uveitis

OBJECTIVE Equine recurrent uveitis (ERU) is a spontaneous disease that is the most common cause of blindness in horses, affecting up to 15% of the horse population. Th17 cells are a major cell population driving the pathogenesis in several mouse models of autoimmune inflammation, including experimental autoimmune uveitis. The purpose of this study is to investigate the role a Th17 cell-mediated response plays in the pathogenesis of ERU. PROCEDURE Banked, Davidsons-fixed equine globes histopathologically diagnosed with ERU (n = 7) were compared immunohistochemically with healthy control globes (n = 7). Immunohistochemical staining was performed using a pan-Leptospira antibody and antibodies against IL-6, IL-17, and IL-23. Additionally, immunostaining was performed for T-cell (CD3) and B-cell (CD79α) markers. Specificity of immunoreactivity was confirmed by western blot analysis. RESULTS Immunohistochemical staining was positive for IL-6, IL-17, and IL-23 within the cytoplasm of nonpigmented ciliary epithelial cells and mononuclear inflammatory cells infiltrating the iris, and ciliary body of ERU horses (n = 7) but negative in controls (n = 7). ERU-affected eyes were CD3 positive (n = 7) and CD79α negative (n = 7). Staining for Leptospira was negative in all ERU and control globes. CONCLUSIONS Strong immunoreactivity for IL-6, IL-17, and IL-23, in conjunction with the fact that T lymphocytes are the predominating inflammatory cells present in ERU, suggests that IL-17-secreting helper T-cells play a role in the pathogenesis of ERU. These findings suggest that horses with ERU may serve as a naturally occurring animal model for autoimmune uveitis.

Immunohistochemical study of matrix metalloproteinases-2 and -9, macrophage inflammatory protein-2 and tissue inhibitors of matrix metalloproteinases-1 and -2 in normal, purulonecrotic and fungal infected equine corneas.

OBJECTIVE Determine the effects of matrix metalloproteinases (MMPs)-2, -9, macrophage inflammatory protein-2 (MIP-2), tissue inhibitors of matrix metalloproteinase (TIMP)-1 and -2 by immunohistochemical expression in fungal affected and purulonecrotic corneas. PROCEDURE Paraffin-embedded equine corneal samples; normal (n = 9), fungal affected (FA; n = 26), and purulonecrotic without fungi (PN; n = 41) were evaluated immunohistochemically for MMP-2, -9, MIP-2, TIMP-1 and -2. The number of immunoreactive inflammatory cells was counted and statistics analyzed. Western blot was performed to detect MMP-2, MMP-9, TIMP-1 and TIMP-2 proteins. RESULTS Matrix metalloproteinases-2, -9, MIP-2, TIMP-1 and -2 immunoreactivity was identified in corneal epithelium of normal corneas, and in corneal epithelium, inflammatory cells, keratocytes, and vascular endothelial cells of both FA and PN samples. Inflammatory cell immunoreactivity was significantly higher in FA and PN samples than in the normal corneas. There was positive correlation between MMP-2 and MIP-2, MMP-9 and MIP-2, and MMP-9 and TIMP-1 in inflammatory cell immunoreactivity in FA samples. There was positive correlation between MMP-9 and MIP-2, MMP-9 and TIMP-2, MIP-2 and TIMP-1, and MIP-2 and TIMP-2 in inflammatory cell immunoreactivity in PN samples. Western blot confirmed the presence of all four proteins in equine corneal samples. CONCLUSION Increased immunoreactivity of MMP-2 and -9 in FA and PN samples is indirectly related to MIP-2 through its role in neutrophil chemo-attraction. Tissue inhibitors of matrix metalloproteinase-1 and TIMP-2 are up-regulated in equine purulonecrotic and fungal keratitis secondary to MMP-2 and MMP-9 expression. The correlation between MMPs -2 and -9, MIP-2, TIMPs -1 and -2 suggests that these proteins play a specific role in the pathogenesis of equine fungal keratitis.

Suspected Sodium Hypochlorite Toxicosis in a Group of Psittacine Birds

Abstract Seven psittacine birds from an aviary of 35 birds developed respiratory disease and died after the premises were cleaned with a commercial solution of undiluted sodium hypochlorite (5% chlorine bleach). Six birds died within 12 days postexposure, and clinical abnormalities were first observed at 6 days. All 7 birds were necropsied and had gross and histopathologic lesions of the trachea, including epithelial deciliation (7/7), ulceration (6/7), squamous metaplasia (5/7), and epithelial hyperplasia (5/7). These tracheal lesions were consistent with inhalation of a noxious agent. Death in these birds was considered to result from hypoxia secondary to blockage of the trachea or pulmonary congestion and, in some cases, sepsis secondary to invasion of bacteria through the altered tracheal mucosa.

Spontaneous Neoplasia in Four Captive Greater Hedgehog Tenrecs (Setifer setosus)

Abstract Little information is available about diseases and pathology of species within the family Tenrecidae, including the greater hedgehog tenrec (Setifer setosus), a Madagascan insectivore. This report summarizes necropsy and histopathologic findings of neoplasia in four captive greater hedgehog tenrecs. Although only four animals are included in this report, neoplasia seems to be a common and significant source of morbidity and mortality in greater hedgehog tenrecs. Types of neoplasia identified include a thyroid follicular-solid carcinoma, two urinary bladder transitional cell carcinomas, uterine endometrial polyps, and multicentric B-cell lymphoma. Due to small sample size, no etiology could be determined, but genetics, viral infection, pesticide treatment, nutrition, or other environmental factors might contribute to the development of neoplasia in this species. This is the first report of neoplasia in greater hedgehog tenrecs.

Is canine hepatocerebellar degeneration syndrome an animal model for carbohydrate-deficient glycoprotein syndrome in humans? An example of sequencing glycoprotein glycans with mass spectrometry.

The clinical symptoms and morphologic features of canine hepatocerebellar degeneration syndrome (CHD) bear striking resemblance to those of human carbohydrate-deficient glycoprotein syndrome (CDGS). The characteristic biochemical and molecular features of human CDGS lie in the truncated carbohydrate side chains of serum transferrin and numerous other glycoproteins of affected persons. Therefore, to explore the biochemical similarities between CHD and CDGS, we compared the structures of the carbohydrate side chains of canine serum transferrin isolated from a normal and a CHD-affected dog. Because of the very small quantity of serum transferrin available from the CHD-affected dog, we used analytical procedures that minimize sample consumption. In this scheme, we used microbore liquid chromatography interfaced to electrospray tandem mass spectrometry to identify and purify the glycopeptides from the tryptic digest of canine serum transferrin. This was followed by a series of exoglycosidase digestions coupled with mass spectrometric detection to sequence the carbohydrate side chains of the glycopeptides. With these procedures we completely characterized the carbohydrate chains attached to serum transferrin isolated from both a normal and a CHD-affected dog. However, we found no discernible differences in glycosylation of the carbohydrate side chains of serum transferrin from these two animals, suggesting that the biochemical defect in puppies with CHD differs from that in children with CDGS.

Biocompatibility of a Novel Microfistula Implant in Nonprimate Mammals for the Surgical Treatment of Glaucoma

PURPOSE The purpose of this study was to evaluate the ocular safety of a novel microfistula implant and its composite materials in an animal model. METHODS The anterior chambers of 12 rabbit eyes were injected with either glutaraldehyde cross-linked porcine gelatin extract or balanced salt solution and were followed by serial slit lamp examinations over 3 days. The eyes of 18 canines underwent microfistula implantation or a sham procedure. The animals were monitored over the subsequent 12 months, using serial slit lamp examinations, indirect ophthalmoscopy, tonometry, specular microscopy, and high-resolution ultrasonography. Ocular tissues were examined histopathologically on postoperative days 7, 30, 90, 180, and 365. RESULTS Glutaraldehyde cross-linked porcine gelatin did not induce significant intraocular inflammation in the rabbit model. The microfistula implant was well tolerated and did not stimulate significant tissue response in the canine eye. The microfistula tube did not undergo structural change or degradation over the course of the study. CONCLUSIONS In nonprimate mammals, the material composing the microfistula implant and the implant itself do not induce significant inflammation or tissue reaction.