Gingival hyperplasia associated with the administration of amlodipine to dogs with degenerative valvular disease (2004-2008).

BACKGROUND: Calcium channel blocking drugs, usually nifedipine and less often amlodipine, have been reported to cause gingival hyperplasia (GH) in humans. HYPOTHESIS: Amlodipine, a dihydropyridine calcium channel blocking drug, can cause GH when administered chronically to older small dogs with degenerative valvular disease. ANIMALS STUDIED: From January 2004 to May 2008, 82 client-owned dogs with degenerative valvular disease and left atrial dilatation were treated with amlodipine in combination with spironolactone and enalapril and followed for >6 months. METHODS: Retrospective study. A chronological observation of GH in 2 dogs treated with amlodipine in 2004 and 2006 prompted the study. Patient histories and medical records of each dog treated with amlodipine for degenerative valvular disease from January 2004 to May 2008 were reviewed. RESULTS: GH was observed by clients and the authors in 7 of 82 (8.5%) dogs. Histologic confirmation of the diagnosis was made in 2 dogs. The minimum duration of treatment before diagnosis of GH was 5 months. GH began to resolve within 2 weeks of discontinuing amlodipine and resolution was complete within 6 months. Amlodipine administration was reinstituted in 1 dog in which GH had resolved, and GH reoccurred within 4 months. CONCLUSION AND CLINICAL IMPORTANCE: Long-term administration of amlodipine to dogs with degenerative valvular disease may cause GH in a small percentage of patients. GH resolves quickly after withdrawal of amlodipine treatment.

Histologic and ultrastructural studies of juvenile onset renal disease in four Rottweiler dogs.

Juvenile onset renal disease is described in 2 male and 2 female young Rottweiler dogs. Histologic changes in all dogs were cystic dilatation of Bowman's space, mesangial hypercellularity, and glomerulosclerosis. Three dogs also had glomerular crescents and moderate to severe interstitial fibrosis. Electron microscopy revealed glomerular basement membranes of variable thickness, with extensive splitting or lamellation of the lamina densa. These ultrastructural findings are similar to those found in people and in other breeds of dogs with inherited defects in type IV collagen.

T cell lymphoma in the lumbar spine of a domestic ferret (Mustela putorius furo).

A 22-month-old castrated male ferret developed acute pelvic limb paresis. Radiographs and computed tomography revealed a soft tissue mass with associated bony lysis of L5, and ultrasound-guided fine needle aspirates suggested that it was a lymphoma. Treatment with prednisone at immunosuppressive doses did not produce any detectable improvement in the ferret's clinical signs and it became moribund less than two weeks after they developed. A postmortem biopsy confirmed the presence of a lymphoma which had invaded the vertebral bone. No viruses were detected by cell culture, or electron microscopy.

Photoreceptor cell dysplasia in two Tippler pigeons.

Two 12-week-old Tippler pigeons were evaluated for ocular abnormalities associated with congenital blindness. The pigeons were emaciated and blind. Biomicroscopy and direct and indirect ophthalmoscopy findings of the Tippler pigeons were normal with the exception of partially dilated pupils at rest. Scotopic (blue stimuli) and photopic monocular electroretinograms were extinguished in the blind Tippler pigeons. Histological and electron microscopy studies revealed reduced numbers of rods and cones, and an absence of the double cone complex. The photoreceptor cells' outer segments were absent, and the inner segments were short and broad. The number of cell nuclei in the outer and inner nuclear layers was decreased, and the internal and external plexiform layers were reduced in width. Photoreceptor cell endfeet with developing synaptic ribbons were present in the external plexiform layer. Inflammatory cell and subretinal debris was not seen. The electroretinographic, histopathological, and ultrastructural findings of the blind Tippler pigeons support the diagnosis of a photoreceptor cell dysplasia.

Feline leukemia virus-associated myelopathy in cats.

Feline leukemia virus (FeLV) infection is associated with distinct neoplastic, hematologic, and immunosuppressive diseases. Here we report on a novel neurologic syndrome in 16 cats infected with FeLV for more than 2 years. Clinical signs consisted of abnormal vocalization, hyperesthesia, and paresis progressing to paralysis. The clinical course of affected cats involved gradually progressive neurologic dysfunction invariably resulting in euthanasia. Microscopically, white-matter degeneration with dilation of myelin sheaths and swollen axons was identified in the spinal cord and brain stem of affected animals. Neither neoplastic nor hematologic diseases commonly associated with FeLV infection were present. Fungal and protozoal infection in one animal was suggestive of impaired immune competence. Immunohistochemical staining of affected tissues revealed consistent expression of FeLV p27 antigens in neurons, endothelial cells, and glial cells. Furthermore, proviral DNA was amplified from multiple sections of spinal cord as well as intestine, spleen, and lymph nodes. These findings suggest that in a proportion of chronically FeLV-infected cats, a virus evolved with cytopathic potential for cells in the central nervous system.

Pathogenesis of six pigeon-origin isolates of Newcastle disease virus for domestic chickens.

The pathogenesis of six pigeon-origin isolates of Newcastle disease virus (NDV) was investigated in chickens. Four isolates were previously defined as the variant pigeon paramyxovirus 1 (PPMV-1), and two isolates were classified as avian paramyxovirus 1 (APMV-1). Birds inoculated with PPMV-1 isolates were euthanatized, and tissue samples were collected at 2, 5, and 10 days postinoculation (DPI). Birds inoculated with APMV-1 isolates died or were euthanatized, and tissue samples were collected at 2, 4, and 5 DPI. Tissues were examined by histopathology, immunohistochemistry (IHC) for the presence of NDV nucleoprotein, and in situ hybridization (ISH) for the presence of viral mRNA for the matrix gene. Spleen sections were stained by the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay and by IHC using an anti-active caspase-3 antibody (IHC-Casp) to detect apoptotic cells. Brain sections of PPMV-1-infected birds were examined by IHC to detect T and B lymphocytes and glial fibrillary acidic protein (GFAP). Histologically, birds inoculated with PPMV-1 isolates had marked lesions in the heart and brain. Presence of viral nucleoprotein and viral mRNA in the affected tissues was confirmed by IHC and ISH, respectively. Numerous reactive astrocytes were observed in brain sections stained for GFAP Among all the isolates, the IHC-Casp demonstrated that apoptosis was very prominent in the ellipsoid-associated cells of the spleen at 2 DPI. Results of the TUNEL assay indicated that apoptotic cells were prominent at 5 DPI and were more randomly distributed. The clinical signs and gross and histopathologic changes observed in the APMV-1-infected birds were characteristic of an extensive infection with highly virulent NDV evident by IHC.

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.

Canine heparan sulfate sulfamidase and the molecular pathology underlying Sanfilippo syndrome type A in Dachshunds.

Heparan sulfate sulfamidase (HSS) is a lysosomal exohydrolase that, when deficient, results in intralysosomal accumulation of heparan sulfate and the clinical phenotype of Sanfilippo syndrome type A. The first animal disease homolog of human Sanfilippo syndrome type A has been recently indentified in Dachshund littermates. To identify the molecular defect, the nucleotide sequences of the normal canine HSS gene and cDNA were determined using PCR-based approaches. The coding region showed 87% nucleotide homology, and 89% amino acid sequence homology, with human HSS. All exon-intron borders were conserved. Sequence analysis of the entire coding region with exon-intron boundaries was performed in the propositus, a healthy littermate, and six unrelated normal dogs. Comparison revealed a 3-bp deletion, 737-739delCCA, resulting in the loss of threonine at position 246 in both alleles of the propositus and in one allele of a healthy littermate. Prediction of the three-dimensional structure of canine HSS, based on homology with human arylsulfatases A and B, suggested the pathogenic effect of this deletion. Six other sequence variations in exons, and 10 in introns, appear to be benign polymorphisms. This study supports the potential development of a canine model of Sanfilippo syndrome type A to evaluate gene therapy for this disorder.

Cellular localization of gene expression for progranulin.

Granulins, also called epithelins, are 6-kD peptides with growth modulatory effects on a variety of cells. The granulin/epithelin precursor supports tumorigenesis in appropriate cell models and is the only growth factor able to overcome the cell cycle block that occurs in murine fibroblasts after deletion of a functional IGF-1 receptor. However, little is known of the role of granulin/epithelin gene products in vivo. To understand the physiological role of granulins it is essential to know the cell types and conditions in which it is expressed. We examined granulin/epithelin gene expression in adult rodents by in situ hybridization. The granulin/epithelin precursor is constitutively expressed in a number of epithelia, particularly in the skin, GI tract, and reproductive system. Other epithelia express the gene less strongly. Progranulin is expressed in immune cells in vivo and in specific neurons in the brain, including Purkinje cells, pyramidal cells of the hippocampus, and some cerebral cortical neurons. Little expression was detected in muscle cell, connective tissue, or endothelium. Cumulatively, these results define the basal gene expression of a new growth factor system and suggest that the progranulin/epithelin gene is multifunctional, with important constitutive roles in epithelial homeostasis, reproductive, immunological, and neuronal function.

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.

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.

Trombidiosis-induced dermatitis in white-tailed deer (Odocoileus virginianus).

During a routine blood collection at a wildlife management checkpoint, several white-tailed deer (Odocoileus virginianus) from Lake Russell Wildlife Management Area, Habersham County, Georgia, were observed to have accumulations of orange granular material around the eyes and mouth accompanied by serous exudate, crusting, and alopecia. Microscopic examination of the granular material disclosed numerous larval mites of the family Trombiculidae. Histologic examination revealed severe chronic diffuse plasmacytic dermatitis with intralesional larval trombiculid mites. Several stylostomes were also identified in the tissue sections. This paper describes the gross and histologic changes associated with severe trombiculid infestation in a white-tailed deer and suggests potential causes for this unusual finding.

Clinical, hematologic, and biochemical features of a syndrome in Bernese mountain dogs characterized by hepatocerebellar degeneration.

Seven related Bernese Mountain Dogs developed a syndrome Characterized by progressive cerebellar and hepatic disease. Clinically, stiffness in the hind limbs, mild incoordination, and a slight head tremor were first noticeable when pups were 4 to 6 weeks old. The condition progressed, causing pups to assume a wide-based stance. Other signs included head bobbing, spontaneous nystagmus, and, finally, paresis. Hematologic findings included leukocytosis with a left shift; normocytic, normochromic anemia; hypoproteinemia, low serum creatinine, and urea nitrogen concentrations; excessive fasting plasma ammonia concentration; and an increase in concentration of serum bile acids. Portal venography performed on 1 dog revealed a small liver and extensive extrahepatic varicosities. Necropsy revealed cerebellar hypoplasia, nodular liver, extensive abdominal varicosities, and ascites. Histologically, degeneration and depletion of Purkinje's cells and vacuolation, degeneration, and nodular regeneration of hepatic tissues were evident. Preliminary analysis of the pedigree was suggestive of an autosomal recessive pattern of inheritance.

Lesions resulting from attempted Shwartzman reaction in turkey poults inoculated with Pasteurella multocida lipopolysaccharide.

Five-week-old turkey poults were given two consecutive intravenous injections (24 hours apart) of highly purified Pasteurella multocida lipopolysaccharide (LPS) in an effort to induce a generalized Shwartzman reaction. There were no gross lesions, and microscopic lesions were limited to focal hepatic necrosis with heterophil infiltration. Hepatic lesions did not differ qualitatively from lesions in turkeys given a single dose of lipopolysaccharide. Margination of heterophils in the pulmonary vasculature was observed in turkeys 4 hours after a single injection of LPS, but it was not present in turkeys given the consecutive injections of LPS. To induce a dermal Shwartzman reaction, turkeys were given intradermal injections of LPS followed by an intravenous injection of LPS 24 hours later. Although no grossly visible hemorrhagic dermal necrosis occurred, microscopic lesions, including heterophil infiltration, vasculitis, thrombosis, and necrosis, were present. Thrombosis and vasculitis were observed only in turkeys given the intravenous and intradermal LPS, whereas the other inflammatory changes were observed in turkeys given the intradermal injection of LPS and intravenous water. Prominent lymphocytic perivascular cuffing at the site of dermal injection was present in all turkeys given intradermal LPS.

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 electron-dense, 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.

Antemortem diagnosis of cholangiocellular carcinoma in a horse.

A 10-year-old Tennessee Walking Horse gelding was admitted to the veterinary teaching hospital for evaluation of intermittent fever, lethargy, and anorexia. Initial laboratory analyses revealed anemia and hyperfibrinogenemia. Abdominocentesis and thoracentesis yielded fluid samples with high nucleated cell counts and total protein concentrations. The tentative diagnosis was nonseptic peritonitis. The horse did not improve after 4 days of antimicrobial treatment, and pitting edema of the ventral midline developed. Thoracic radiography and ultrasonography revealed consolidation of the ventral aspect of the lung fields and pleural effusion. Pleuroscopy of the right hemithorax revealed pleural effusion and a soft-tissue mass in the caudal portion of the mediastinum. Findings on biopsy of the liver and mediastinal mass led to a presumptive diagnosis of metastatic cholangiocellular carcinoma. The horse was euthanatized, and the diagnosis was confirmed at necropsy.