A lentivirus-vectored feline erythropoietin gene therapy strategy in tissue culture and rodent models for the potential treatment of chronic renal disease-associated anemia

OBJECTIVE

The aim of this study was to assess the efficacy and safety of a third-generation lentivirus-based vector encoding the feline erythropoietin (EPO) (feEPO) gene in vitro and in rodent models in vivo. This vector incorporates a genetic mechanism to facilitate the termination of the therapeutic effect in the event of supraphysiologic polycythemia, the herpes simplex virus thymidine kinase (HSV-TK) "suicide gene."

ANIMALS

CFRK cells and replication-defective lentiviral vectors encoding feEPO were used for in vitro experiments. Eight Fischer rats were enrolled in the pilot in vivo study, 24 EPO-deficient mice were used in the initial mouse study, and 15 EPO-deficient mice were enrolled in the final mouse study.

METHODS

Efficacy of a third-generation lentivirus encoding feEPO was determined in vitro using western blot assays. Subsequently, in a series of rodent experiments, animals were administered the viral vector in progressively increasing inoculation doses with serial measurements of blood packed cell volume (PCV) over time.

RESULTS

We documented production of feEPO protein in transduced CRFK cells with subsequent cessation of production when treated with the HSV-TK substrate ganciclovir. In vivo, we demonstrated variably persistent elevated PCV values in treated rats and mice with eventual return to baseline values over time.

CLINICAL RELEVANCE

These results provide justification for a lentiviral gene therapy approach to the treatment of nonregenerative anemia associated with chronic renal disease in cats.

Serologic, Virologic and Pathologic Features of Cats with Naturally Occurring Feline Infectious Peritonitis Enrolled in Antiviral Clinical Trials

Feline infectious peritonitis (FIP) is a multisystemic, generally lethal immuno-inflammatory disease of domestic cats caused by an infection with a genetic variant of feline coronavirus, referred to as the FIP virus (FIPV). We leveraged data from four different antiviral clinical trials performed at the University of California, Davis. Collectively, a total of 60 client-owned domestic cats, each with a confirmed diagnosis of naturally occurring FIP, were treated with a variety of antiviral compounds. The tested therapies included the antiviral compounds GS-441524, remdesivir, molnupiravir and allogeneic feline mesenchymal stem/stroma cell transfusions. Four client-owned cats with FIP did not meet the inclusion criteria for the trials and were not treated with antiviral therapies; these cats were included in the data set as untreated FIP control cats. ELISA and Western blot assays were performed using feline serum/plasma or ascites effusions obtained from a subset of the FIP cats. Normalized tissue/effusion viral loads were determined in 34 cats by a quantitative RT-PCR of nucleic acids isolated from either effusions or abdominal lymph node tissue. Twenty-one cats were PCR "serotyped" (genotyped) and had the S1/S2 region of the coronaviral spike gene amplified, cloned and sequenced from effusions or abdominal lymph node tissue. In total, 3 untreated control cats and 14 (23.3%) of the 60 antiviral-treated cats died or were euthanized during (13) or after the completion of (1) antiviral treatment. Of these 17 cats, 13 had complete necropsies performed (10 cats treated with antivirals and 3 untreated control cats). We found that anticoronaviral serologic responses were persistent and robust throughout the treatment period, primarily the IgG isotype, and focused on the viral structural Nucleocapsid and Membrane proteins. Coronavirus serologic patterns were similar for the effusions and serum/plasma of cats with FIP and in cats entering remission or that died. Viral RNA was readily detectable in the majority of the cats in either abdominal lymph node tissue or ascites effusions, and all of the viral isolates were determined to be serotype I FIPV. Viral nucleic acids in cats treated with antiviral compounds became undetectable in ascites or abdominal lymph node tissue by 11 days post-treatment using a sensitive quantitative RT-PCR assay. The most common pathologic lesions identified in the necropsied cats were hepatitis, abdominal effusion (ascites), serositis, pancreatitis, lymphadenitis, icterus and perivasculitis. In cats treated with antiviral compounds, gross and histological lesions characteristic of FIP persisted for several weeks, while the viral antigen became progressively less detectable.

Gingival squamous cell carcinoma in 2 lions under managed care

Neoplasia is one of the main causes of euthanasia in geriatric captive nondomestic felids. However, few studies have examined oral tumors in these animals. We describe here the clinicopathologic features of gingival squamous cell carcinoma (SCC) in 2 lions (Panthera leo) from separate zoologic collections. In both cases, the lions had a history of sialorrhea, bloody oral discharge, and anorexia. Autopsy findings in both lions were similar and were characterized by poorly circumscribed, friable, and bloody gingival masses with grossly apparent invasion of the mandibular bone; a pathologic fracture was observed in 1 case. Histologically, the masses consisted of poorly circumscribed, unencapsulated, densely cellular proliferations of neoplastic epithelial cells arranged in irregular islands, cords, and anastomosing trabeculae with formation of keratin pearls, which, coupled with positive immunohistochemistry for pancytokeratin, were diagnostic for SCC. Although no metastases were found in either animal, both lions were ultimately euthanized because of poor prognosis.

Pathological Spectrum of Ovine Pulmonary Adenocarcinoma in Small Ruminants: A Focus on the Mixed Form

Ovine pulmonary adenocarcinoma (OPA) is a contagious respiratory tumor of small ruminants, manifesting in chronic weight loss and respiratory failure. Infection with the betaretrovirus jaagsiekte sheep retrovirus (JSRV) is the cause of OPA. Here, we describe the gross and microscopic features of twenty-six sheep and one goat with naturally occurring JSRV-associated OPA. All the animals included in this study had pulmonary lesions morphologically consistent with OPA, but the majority of the observed lesions demonstrated features of both the classical and the atypical form of OPA, and were, therefore, classified grossly as mixed. The gross lesions were located mainly in the cranial pulmonary lobes, were multifocal to coalescing, variable in number and size, flat to slightly raised, firm, and white to grey. Histologically, the cases were classified according to the predominant architectural patterns as lepidic, papillary, acinar, or mixed; the mixed histological pattern was the most prevalent. The aim of this study was to describe the gross and microscopic spectrum of OPA in naturally infected small ruminants from Spain. The mixed form of OPA is less commonly reported, and can be confused with other concurrent pulmonary pathologies (such as BALT hyperplasia in SRLV-associated pneumonia or lungworm granulomas).

The Late Asymptomatic and Terminal Immunodeficiency Phases in Experimentally FIV-Infected Cats-A Long-Term Study

Feline immunodeficiency virus (FIV) is a lentivirus in the family Retroviridae that infects domestic cats resulting in an immunodeficiency disease featuring a progressive and profound decline in multiple sets of peripheral lymphocytes. Despite compelling evidence of FIV-associated immunopathology, there are conflicting data concerning the clinical effects of FIV infection on host morbidity and mortality. To explore FIV-associated immunopathogenesis and clinical disease, we experimentally inoculated a cohort of four specific pathogen-free kittens with a biological isolate of FIV clade C and continuously monitored these animals along with two uninfected control animals for more than thirteen years from the time of inoculation to the humane euthanasia endpoint. Here, we report the results obtained during the late asymptomatic and terminal phases of FIV infection in this group of experimentally FIV-infected cats.

Efficacy of Oral Remdesivir Compared to GS-441524 for Treatment of Cats with Naturally Occurring Effusive Feline Infectious Peritonitis: A Blinded, Non-Inferiority Study

Nucleoside analogs GS-441524 and remdesivir (GS-5734) are effective in treating cats with feline infectious peritonitis (FIP). However, no studies have compared the efficacy between antiviral medications. The objective of this study was to evaluate the efficacy of orally administered GS-442514 (12.5-15 mg/kg) compared to orally administered remdesivir (25-30 mg/kg) in a double-blinded non-inferiority trial. Eighteen cats with effusive FIP were prospectively enrolled and randomly assigned to receive either GS-442514 or remdesivir. Cats were treated daily for 12 weeks and evaluated at week 0, 12, and 16. Survival and disease remission at week 16 were compared between groups. Five of 9 (55%) cats treated GS-441524 and 7/9 (77%) cats treated with remdesivir survived, with no difference in survival rate (p = 0.2). Remdesivir fulfilled the criteria for non-inferiority with a difference in survival of 22% (90% CI; -13.5-57.5%). Three of the 18 cats died within 48 h of enrollment. Excluding these cats, 5/6 (83%) of the cats treated with GS-441524 and 7/9 (77%) of the cats treated with remdesivir survived. These findings suggest that both orally administered GS-441524 and remdesivir are safe and effective anti-viral medications for the treatment of effusive FIP. Further optimization of the first 48 h of treatment is needed.

Odontogenic-like neoplasms of the rabbit cheek: pathological features and comparison to cutaneous trichoblastoma and jaw-associated ameloblastoma

Odontogenic neoplasms demonstrate unique histopathological features and are thought to arise from the germinal tissues of the developing tooth germ, effectively restricting their anatomic origin to the tooth-bearing regions of the jaw and directly associated soft tissues of the oral cavity. Ectopic odontogenic-like neoplasms located in the skin of cats, rabbits, and human beings challenge these assumptions. Here we describe the clinical, pathological, and immunohistochemical features of 6 spontaneously occurring odontogenic-like neoplasms arising in the cutaneous tissue of the cheek in client-owned pet rabbits, including ameloblastoma-like (n = 3), ameloblastic fibroma-like (n = 2), and ameloblastic carcinoma-like neoplasms (n = 1). Microscopically, all the cheek tumors featured neoplastic epithelium exhibiting odontogenic architectural structures (plexiform ribbons, anastomosing trabeculae, follicles, cysts, and irregular structures with rounded botryoid protuberances) and 1 or more cardinal odontogenic epithelial features (basal palisading, antibasilar nuclei, and central stellate reticulum-like cells). The pancytokeratin, cytokeratin 5/6, cytokeratin 14, and vimentin immunohistochemical patterns of these odontogenic-like lesions were most similar to those of jaw-associated ameloblastoma and differed from those of cutaneous trichoblastoma. All neoplasms were narrowly excised, and for lesions with clinical follow-up information, none had evidence of recurrence 1-7 months after surgical removal. Although evidence suggests that these odontogenic-like tumors of the rabbit cheek may be derived from ectopic rests of transformed tooth germ, the histogenesis of these lesions remains unresolved.

Medical Management of Canine Chronic Ulcerative Stomatitis Using Cyclosporine and Metronidazole

Canine chronic ulcerative stomatitis (CCUS) is a spontaneously occurring, painful, and often debilitating condition of the oral cavity, with a suspected immune-mediated component. The response to pharmacological treatment is generally poor, thus the need to identify more effective medical therapies for this condition. This article describes a prospective clinical trial that was designed to evaluate the efficiency of a combination of cyclosporine and metronidazole in managing CCUS. The hypothesis was that a combination of cyclosporine and metronidazole would effectively minimize clinical signs associated with CCUS. Ten client-owned dogs with a biopsy-confirmed diagnosis consistent with CCUS were prescribed cyclosporine (5 mg/kg) for 1 week, followed by the addition of metronidazole (15-20 mg/kg), both administered orally once daily. The cyclosporine dosage interval was lengthened over time. Dogs were observed for a 6-month period and evaluated using a 32-point Canine Ulcerative Stomatitis Disease Activity Index (CUSDAI). Regular cyclosporine therapeutic drug monitoring was also conducted by the measurement of whole blood cyclosporine levels and the pharmacodynamic assessment of the T-cell expression of IL-2. The results demonstrated that a combination of cyclosporine and metronidazole was effective in minimizing the clinical signs of CCUS and in reducing CUSDAI scores. Neither blood cyclosporine levels nor the T-cell expression of IL-2 predicted improvement in clinical signs and CUSDAI scores, although there was a correlation between blood drug concentrations and the suppression of T-cell IL-2 expression. The evaluation of clinical signs and CUSDAI scores appears to be the most effective means of assessing response to therapy, and therapeutic drug level monitoring does not appear to be routinely indicated.

Use of Enrofloxacin and Hydrotherapy in the Management of Fibrodysplasia Ossificans Progressiva (FOP) in a Savannah Cat

FOP is a rare genetic condition, described mainly in man and cats, characterized by progressive, painful debilitation and shortened lifespan. A 10-month-old neutered male Savannah cat was referred for progressive gait abnormalities and multifocal firm masses within the soft-tissues that were unresponsive to previous treatment. Diagnosis of FOP was based on histopathological evaluation of intralesional biopsies, which revealed osteo-cartilaginous metaplasia and fibrocellular proliferation with intralesional chondrogenesis and endochondral ossification. The cat was managed with 5 mg/kg BID enrofloxacin and hydrotherapy for 3 years until acute death. During that three-year period, the cat displayed consistent improvement in endurance, quality of life, and range of motion. Postmortem histopathology further confirmed the diagnosis of FOP via identification of intramuscular and intra-fascial ossification with lymphoplasmacytic infiltration, degeneration, and regeneration of adjacent myocytes. To the authors' knowledge, this is the first report of long-term enrofloxacin treatment and hydrotherapy for the management of FOP in a cat, leading to improved mobility and survival time, and the first report of FOP in an exotic breed cat.

An Optimized Bioassay for Screening Combined Anticoronaviral Compounds for Efficacy against Feline Infectious Peritonitis Virus with Pharmacokinetic Analyses of GS-441524, Remdesivir, and Molnupiravir in Cats

Feline infectious peritonitis (FIP) is a fatal disease of cats that currently lacks licensed and affordable vaccines or antiviral therapeutics. The disease has a spectrum of clinical presentations including an effusive ("wet") form and non-effusive ("dry") form, both of which may be complicated by neurologic or ocular involvement. The feline coronavirus (FCoV) biotype, termed feline infectious peritonitis virus (FIPV), is the etiologic agent of FIP. The objective of this study was to determine and compare the in vitro antiviral efficacies of the viral protease inhibitors GC376 and nirmatrelvir and the nucleoside analogs remdesivir (RDV), GS-441524, molnupiravir (MPV; EIDD-2801), and β-D-N⁴-hydroxycytidine (NHC; EIDD-1931). These antiviral agents were functionally evaluated using an optimized in vitro bioassay system. Antivirals were assessed as monotherapies against FIPV serotypes I and II and as combined anticoronaviral therapies (CACT) against FIPV serotype II, which provided evidence for synergy for selected combinations. We also determined the pharmacokinetic properties of MPV, GS-441524, and RDV after oral administration to cats in vivo as well as after intravenous administration of RDV. We established that orally administered MPV at 10 mg/kg, GS-441524 and RDV at 25 mg/kg, and intravenously administered RDV at 7 mg/kg achieves plasma levels greater than the established corresponding EC₅₀ values, which are sustained over 24 h for GS-441514 and RDV.

Clinical, Diagnostic and Histological Findings Involving Cheek Teeth Hypercementosis in Nine Horses

Hypercementosis is infrequently reported to affect the cheek teeth of horses and presents as mineral deposits either attached (peripheral) or solitary ovoid (nodular) structures in the tooth bearing region. There is overlap between radiological and histological appearance of hypercementosis, cementoma, and equine odontoclastic tooth resorption and hypercementosis (EOTRH). The clinical presentation, imaging features, surgical management, and histological findings of nine horses that presented for dental lesions and associated hypercementosis of cheek teeth are reported. Horses were 4-15 years old and presented for either nasal discharge or facial swelling. Peripheral and nodular mineral structures were identified using radiographs or computed tomography in six and three horses, respectively. Eight of nine cases involved maxillary cheek teeth. Of six cases with peripheral hypercementosis, three had enlargement of the apical cross-sectional area that was greater than the coronal cross-sectional area thus preventing extraction along the normal eruption pathway and necessitating sectioning (two cases) and repulsion. Nodular hypercementosis lesions were extracted in three of the four cases. Post-extraction complications occurred in five cases; four cases required additional procedures. All horses returned to their intended use, ie riding or pasture. Histology of extracted dental and proliferative mineral material revealed hypercementosis characterized by large sheets of eosinophilic matrix with lacunae (usually empty; presumed artifact) and frequent, irregular, basophilic cement lines. All cases had evidence of chronic inflammation, such as caries, chronic fractures and/or pulpitis. The findings of this case series share many features with previous published descriptions of cementoma and with histological findings of hypercementosis lesions of EOTRH. Further investigation into differentiation of these entities is warranted.

Ameloblastic carcinoma in horses: case report and literature review

Ameloblastic carcinoma is a malignant odontogenic neoplasm that has been reported only rarely in veterinary species. A 16-y-old Arabian crossbred mare was presented for evaluation of a hard mass on the body of the mandible, with evidence of osteolysis on radiographs. Incisional biopsies revealed an invasive neoplasm comprised of spindloid epithelial cells with a high mitotic count and partial dual cytokeratin-vimentin immunoreactivity. The horse was euthanized because of rapid tumor progression 3 mo after presentation. Postmortem evaluation revealed partial obliteration of the mandible by a large, firm-to-hard, tan, locally destructive and invasive mass with no gross or histologic evidence of metastasis. Postmortem histology revealed a poorly differentiated epithelial neoplasm with variably prominent features suggestive of odontogenic histogenesis: a plexiform ribbon architecture, infrequent basilar palisading with antibasilar nuclei, rare basilar cytoplasmic clearing, subepithelial matrix hyalinization, and partial dual cytokeratin-vimentin immunoreactivity. Features of malignancy included regions of necrosis, pronounced cellular atypia, a high mitotic count, extensive tissue invasion and local tissue destruction, and extension of neoplastic cells beyond the margins of the mandibular bone. Collectively, these features are most consistent with mandibular ameloblastic carcinoma. Including our case described here, ameloblastic carcinoma has been reported in only 5 horses. The microscopic features reported most consistently are dual cytokeratin-vimentin immunoreactivity, a high mitotic count, and basilar palisading. Ameloblastic carcinoma should be considered as a differential diagnosis for rapidly growing, locally invasive masses arising from the dentate jaw of horses.

Osteochondral necrosis of the femoral condyles in Thoroughbred foals: eight cases (2008–2018)

OBJECTIVE

To describe clinical, imaging, gross, and histopathological abnormalities associated with osteochondral necrosis of the femoral condyles in foals and identify features suggestive of a common pathogenesis.

ANIMALS

8 Thoroughbred foals euthanized with a presumptive diagnosis of necrosis of the femoral condyles.

PROCEDURES

Postmortem CT was performed on all distal femoral epiphyseal samples. The articular epiphyseal cartilage complex (AECC) of affected distal femurs was examined grossly and histologically, focusing on lesions of interest identified on CT images.

RESULTS

7 foals were between 9 and 23 days old at the time of euthanasia; 1 foal was 85 days old. Concurrent illness (neonatal maladjustment syndrome, neonatal isoerythrolysis, or infection such as enteritis and omphalitis) was diagnosed in 7 foals. The characteristic antemortem radiographic and postmortem CT finding was a crescent-shaped osteochondral flap displaced from the affected medial femoral condyle. Synovial fluid cytology from affected joints was either within normal limits or consistent with mild inflammation. Histologically, all lesions were characterized by osteochondral necrosis and detachment of the AECC. In 6 foals, polymorphonuclear cells were found within growth cartilage canals, representing septic cartilage canals.

CLINICAL RELEVANCE

Osteochondral necrosis was interpreted to be secondary to bacterial colonization of the distal femoral AECC, evidenced by septic cartilage canals identified in 6 of 8 foals. This uncommon condition was previously thought to arise from an ischemic event, but the disease process was not well understood. An improved understanding of the pathogenesis of osteochondral necrosis is the first step in formulating more successful preventative and treatment strategies.

Investigation of monotherapy and combined anticoronaviral therapies against feline coronavirus serotype II in vitro

OBJECTIVES

Feline infectious peritonitis (FIP), caused by genetic mutants of feline enteric coronavirus known as FIPV, is a highly fatal disease of cats with no currently available vaccine or US Food and Drug Administration-approved cure. Dissemination of FIPV in affected cats results in a range of clinical signs, including cavitary effusions, anorexia, fever and lesions of pyogranulomatous vasculitis and perivasculitis, with or without central nervous system or ocular involvement. The objectives of this study were to screen an array of antiviral compounds for anti-FIPV (serotype II) activity, determine cytotoxicity safety profiles of identified compounds with anti-FIPV activity and strategically combine identified monotherapies to assess compound synergy against FIPV in vitro. Based upon clinically successful combination treatment strategies for human patients with HIV and hepatitis C virus infections, we hypothesized that a combined anticoronaviral therapy approach featuring concurrent multiple mechanisms of drug action would result in an additive or synergistic antiviral effect.

METHODS

This study screened 90 putative antiviral compounds for efficacy and cytotoxicity using a multimodal in vitro strategy, including plaque bioassays, real-time RT-PCR viral inhibition and cytotoxicity assays.

RESULTS

Through this process, we identified 26 compounds with effective antiviral activity against FIPV, representing a variety of drug classes and mechanisms of antiviral action. The most effective compounds include GC376, GS-441524, EIDD2081 and EIDD2931. We documented antiviral efficacy for combinations of antiviral agents, with a few examined drug combinations demonstrating evidence of limited synergistic antiviral activity.

CONCLUSIONS AND RELEVANCE

Although evidence of compound synergy was identified for several combinations of antiviral agents, monotherapies were ultimately determined to be the most effective in the inhibition of viral transcription.

Rickets in a Thoroughbred-cross foal: case report and review of the literature

Rickets is a metabolic bone disease associated with failure of endochondral ossification and impaired osteoid mineralization in growing animals. As a consequence, affected individuals can develop gross and microscopic bone malformations. The most common causes of rickets in domestic species include vitamin D and phosphorus deficiency. Rickets has been described in multiple species; however, comprehensive postmortem characterizations with confirmatory histopathology in equids have not been published. A 6-mo-old, Thoroughbred-cross foal was diagnosed with rickets based on gross autopsy findings and microscopic examination of the ribs and long bones. Grossly, all costochondral junctions of the ribs were enlarged with a "rachitic rosary" appearance, and there were multiple fracture calluses in the rib bodies. Epiphyses and metaphyses of the long bones appeared widened on sagittal section, and their physes were irregularly thickened. Histologically, there were poorly organized columns of hypertrophic chondrocytes within the physes of affected bones, islands of chondrocytes embedded within the primary and secondary spongiosa, and faintly eosinophilic seams of poorly mineralized osteoid within the bone trabeculae. Areas of focally increased osteoclastic activity were observed in some of the sections, perhaps pointing to a more complex metabolic bone disease in a growing animal. Low serum concentrations of calcium and 25-hydroxyvitamin D were detected in an antemortem sample. The pathogenesis of these imbalances was not definitively established, but lack of sunlight exposure, low concentration of vitamin D precursors in the diet (perhaps secondary to malnutrition), or both, were suspected; a genetic basis cannot be ruled out.

Daylight-Induced Antibacterial and Antiviral Nanofibrous Membranes Containing Vitamin K Derivatives for Personal Protective Equipment

During the development of antibacterial and antiviral materials for personal protective equipment (PPE), daylight active functional polymeric materials containing vitamin K compounds (VKs) and impacts of polymer structures to the functions were investigated. As examples, hydrophobic polyacrylonitrile (PAN) and hydrophilic poly(vinyl alcohol-co-ethylene) (PVA-co-PE) polymers were directly blended with three VK compounds and electrospun into VK-containing nanofibrous membranes (VNFMs). The prepared VNFMs exhibited robust photoactivity in generating reactive oxygen species (ROS) under both daylight (D65, 300-800 nm) and ultraviolet A (UVA, 365 nm) irradiation, resulting in high antimicrobial and antiviral efficiency (>99.9%) within a short exposure time (<90 min). Interestingly, the PVA-co-PE/VK₃ VNFM showed higher ROS production rates and better biocidal functions than those of the PAN/VK₃ VNFM under the same photoirradiation conditions, indicating that PVA-co-PE is a better matrix polymer material for these functions. Moreover, the prepared PVA-co-PE/VK₃ VNFM maintains its powerful microbicidal function even after five times of repeated exposures to bacteria and viruses, showing the stability and reusability of the antimicrobial materials. The fabrication of photoinduced antimicrobial VNFMs may provide new insights into the development of non-toxic and reusable photoinduced antimicrobial materials that could be applied in personal protective equipment with improved biological protections.

Oral Lesions in Captive Nondomestic Felids With a Focus on Odontogenic Lesions

Odontogenic lesions are well described in domestic cats, but published literature describing these lesions in nondomestic felids is limited. This study reports oral lesions in 109 captive, non-domestic felids. Ten cases of odontogenic lesions were diagnosed, including 9 with fibromatous epulis of periodontal ligament origin (FEPLO) and one odontogenic cyst in a cougar. FEPLO was common in lions. FEPLO did not recur after surgical removal in any of the 3 cases for which follow-up information was available. Increased occurrences of oral papillomas in snow leopards and eosinophilic granulomas in tigers were identified, which is consistent with the reported literature. With the exception of oral papillomas in snow leopards and FEPLO in lions, the spectrum of oral lesions in nondomestic felids was similar to what is reported in domestic cats, with squamous cell carcinoma being the most common oral malignancy, and stomatitis/gingivitis/glossitis accounting for approximately one third of all cases. Rare diagnoses with one case each included hemangioma, fibrosarcoma, melanoma, cleft palate, and glossal amyloidosis.

Osteomalacia With Hyperostosis in Captive Lesser Hedgehog Tenrecs (Echinops telfairi)

Four captive, lesser hedgehog tenrecs (Echinops telfairi) were euthanized for soft bones that prevented normal mastication and/or ambulation. Antemortem radiographs (available in 2 cases) revealed osteopenia. Antemortem bloodwork (available in 2 cases) revealed hypophosphatemia. Dietary history (available in 2 cases) indicated the animals were eating only insects. Histologically, all examined bones had wide osteoid seams that caused expansion of the cortices. Osteoid deposition was exuberant and it partially filled marrow cavities (hyperostosis). Nondecalcified sections of bone (available in 2 cases) revealed that osteoid was poorly mineralized, consistent with osteomalacia. Insects are poor dietary sources of vitamin D, and dietary vitamin D deficiency is considered the most likely cause for metabolic bone disease in these animals.

Chondrosesamoidean ligament enthesopathy: Prevalence and findings in a population of lame horses imaged with positron emission tomography

BACKGROUND

Increased ¹⁸ F-Sodium Fluoride (¹⁸ F-NaF) uptake at the chondrosesamoidean ligament (ChSL) attachment on the distal phalanx was identified in an exploratory positron emission tomography (PET) study. The prevalence and significance of this lesion has not been previously investigated.

OBJECTIVES

The goal of this study was to assess the prevalence of this lesion, its association with other imaging findings and with clinical signs.

STUDY DESIGN

Retrospective cross-sectional analytical study.

METHODS

All horses with ¹⁸ F-NaF PET and computed tomography (CT) imaging of the feet performed between October 2016 and December 2017 were included in the study. All PET scans were independently assessed by two radiologists for increased uptake at the ChSL attachment site and concurrent imaging was reviewed. Clinical findings, treatment and outcome were retrieved from the medical records.

RESULTS

Fourteen of 30 horses (20/56 feet) had increased ¹⁸ F-NaF uptake in the region of interest. ChSL enthesopathy was the primary lesion in three horses. Other PET abnormalities included navicular bone uptake (13 feet) and ipsilateral palmar process uptake (9 feet). There was no significant association between ChSL enthesopathy and other lesions. ChSL enthesopathy was significantly associated with foot lameness. CT abnormalities at the ChSL attachment were initially identified in one foot, and retrospectively noted in another five following the results of PET imaging.

MAIN LIMITATIONS

The study is retrospective and there was a limited sample size.

CONCLUSIONS

PET led to identification of ChSL enthesopathy in a large proportion of horses with foot pain. This finding is most commonly associated with other lesions but may also represent the main abnormality. The axial border of the palmar processes of the distal phalanx should be carefully assessed on cross sectional imaging to identify this lesion. ChSL enthesopathy may be an important but previously not recognised component of foot pathology in horses.

Odontomas in Frogs

Odontomas are variably differentiated, hamartoma-like proliferations of odontogenic epithelium, pulp ectomesenchyme (odontoblasts), and dental matrix. Frogs are polyphyodont and homodont. Their teeth also differ from mammals in that they are restricted to the upper jaw in adults and lack a periodontal ligament and cementum, attaching directly to the underlying bone. Odontomas were identified in an African clawed frog (Xenopus laevis), a false tomato frog (Dyscophus guineti), and a tomato frog of unknown species (Dyscophus sp.). All of the examined odontomas were composed of numerous tooth-like structures comprising an arc of dentinal matrix lined on the convex surface by ameloblasts and on the concave surface by odontoblasts. Masson's trichrome and immunohistochemistry with pan-cytokeratin supported these findings. The pathogenesis of these lesions may be displacement of the dental lamina, which has been shown in research studies to lead to de novo proliferation of dental elements in frogs.

Pathologic Features of the Intervertebral Disc in Young Nova Scotia Duck Tolling Retrievers Confirms Chondrodystrophy Degenerative Phenotype Associated With Genotype

Chondrodystrophy results in predictable and progressive biochemical and structural changes to the intervertebral disc, resulting in early onset degeneration and dystrophic mineralization of the disc. Accelerated degeneration and mineralization of the intervertebral disc are common in multiple dog breeds and can result in compromised function, herniation, pain, and a variety of neurological sequelae. A mutation responsible for chondrodystrophy in dogs has been identified as an aberrant fibroblast growth factor 4 (FGF4) retrogene insertion on chromosome 12 (CFA12) and is associated with short stature of the Nova Scotia Duck Tolling Retriever. Segregation of the CFA12 FGF4 retrogene in this dog breed provides an opportunity to examine the effect of retrogene presence on radiographic and histologic appearance of chondrodystrophic disc degeneration within a single breed. Here we found that in the intervertebral discs isolated from 2 dogs with the CFA12 FGF4 genotype, the nucleus pulposus was largely replaced by cartilaginous tissue, and physaliferous notochordal cells were rarely if ever identified. These findings are in contrast to the normal histologic findings in 2 breed-matched dogs lacking the mutation. The findings are consistent with premature chondroid degeneration of the intervertebral disc and suggest that the presence of the CFA12 FGF4 retrogene is sufficient to cause the chondrodystrophic phenotype.

Mixed odontogenic tumors in four young dogs: ameloblastic fibroma and ameloblastic fibro-odontoma

Ameloblastic fibroma (AF) and ameloblastic fibro-odontoma (AFO) are mixed odontogenic tumors (odontogenic tumors with induction) that are reported only rarely in dogs. These tumors are histologically complex and, to a degree, recapitulate the early stages of tooth development, comprising 2 types of tissue: neoplastic odontogenic epithelium, and induced ectomesenchyme (dental pulp). AFOs are distinguished from AFs by the additional presence of hard dental matrices such as dentin. Herein, we describe the key diagnostic features of AF and AFO in 4 young dogs.

Investigation of immune cell markers in feline oral squamous cell carcinoma

Squamous cell carcinoma is the most common oral cancer in the cat and presents as a locally aggressive lesion for which an effective therapeutic protocol remains elusive. Feline oral squamous cell carcinoma (OSCC) shares many clinical characteristics with human head and neck squamous cell carcinoma (HNSCC). Accordingly, present studies were conducted to determine similarities for immune markers shared by feline OSCC and human HNSCC. Biopsies harvested from a feline patient cohort-1 (n = 12) were analyzed for lymphoid cell infiltrates by immunohistochemistry (IHC). Results revealed unique patterns of T cell infiltration involving both neoplastic epithelium and stroma that were detected in most patient tumor biopsies (92%) examined by IHC staining for CD3. Intratumoral B cell infiltrates were detected within tumor stroma only, based on IHC staining for CD79a and CD20 for all patients within the same cohort-1. Infiltration of tumors by a regulatory CD4 T cell subset (Tregs) defined by expression of the forkhead transcription factor FoxP3, was also detected in biopsies from 57% of patients and involved infiltration of neoplastic epithelium and stroma. Patient biopsies were also examined for expression of immunomodulator cyclooxygenase (COX)-2 and revealed positive but weak staining of neoplastic epithelium in a significant proportion of cases (75%). Interestingly, COX-2 expression was detected in both neoplastic epithelium and stroma. Blood collected from a second cohort of feline OSCC patients (n = 9) revealed an increased frequency of circulating CD4+FoxP3+ T cells when compared to healthy adult controls (n = 7) (P = 0.045), although frequencies of CD4+CD25+FoxP3+ T cells were comparable between patients and healthy pet cat controls. Lastly, biopsies from feline OSCC patients were characterized for histologic subtype using a classification scheme previously described for human HNSCC. This analysis revealed the conventional subtype as the predominant variant (75%) with conventional subtypes split evenly between well differentiated and moderately differentiated carcinomas. Two cases were classified as papillary and one case as basaloid subtypes. Correlations between subtype, immune marker scores or circulating Treg frequencies and clinical characteristics or outcome were not detected, most likely due to small patient numbers within patient cohorts. However, findings from these studies provide a preliminary step in the characterization of immune and histologic markers that will be critical to defining prognostic immune markers for feline OSCC and potential targets for testing of immunotherapeutics also relevant to human HNSCC in future studies.

Bone formation transcripts dominate the differential gene expression profile in an equine osteoporotic condition associated with pulmonary silicosis

Osteoporosis has been associated with pulmonary silicosis in California horses exposed to soils rich in cytotoxic silica dioxide crystals, a syndrome termed silicate associated osteoporosis (SAO). The causal mechanism for the development of osteoporosis is unknown. Osteoporotic lesions are primarily located in bone marrow-rich sites such as ribs, scapula and pelvis. Gene transcription patterns within bone marrow and pulmonary lymph nodes of affected horses may offer clues to disease pathobiology. Bone marrow core and tracheobronchial lymph node tissue samples harvested postmortem from affected and unaffected horses were examined histologically and subjected to RNA sequencing (RNA-seq). Sequenced data were analyzed for differential gene expression and gene ontology. Metatranscriptomic and metagenomic assays evaluated samples for infectious agents. Thirteen of 17 differentially expressed transcripts in bone marrow were linked to bone and cartilage formation such as integrin binding bone sialoprotein (log2FC = 3.39, PFDR = 0.013) and chondroadherin (log2FC = 4.48, PFDR = 0.031). Equus caballus solute carrier family 9, subfamily A2 (log2FC = 3.77, PFDR = 0.0034) was one of the four differentially expressed transcripts linked to osteoclast activity. Osteoblasts were hyperplastic and hypertrophic in bone marrow from affected horses. Biological pathways associated with skeletal morphogenesis were significantly enriched in affected horses. The 30 differentially expressed genes in affected lymph nodes were associated with inflammatory responses. Evidence of infectious agents was not found. The SAO affected bone marrow molecular signature demonstrated increased transcription and heightened activation of osteoblasts. Increased osteoblastic activity could be part of the pathological mechanism for osteoporosis or a compensatory response to the accelerated osteolysis. Transcriptome data offer gene targets for inquiries into the role of osteocytes and osteoblasts in SAO pathogenesis. Viral or bacterial infectious etiology in SAO is less likely based on metatranscriptomic and metagenomic data but cannot be completely ruled out.

Multiple, Independent T Cell Lymphomas Arising in an Experimentally FIV-Infected Cat during the Terminal Stage of Infection

Our laboratory has serially reported on the virologic and immunopathologic features of a cohort of experimental feline immunodeficiency virus (FIV)-infected cats for more than eight years. At 8.09 years post infection (PI), one of these animals entered the terminal stage of infection, characterized by undulating hyperthermia, progressive anorexia, weight loss, and pancytopenia; the animal was not responsive to therapeutic interventions, necessitating euthanasia six weeks later (8.20 years PI). Subsequent analyses indicated that neoplastic lymphocytes infiltrated multiple cervical lymph nodes and a band-like region of the mucosal lamina propria within a segment of the intestine. Immunohistochemistry and T cell clonality testing determined that the nodal and intestinal lesions were independently arising from CD3 T cell lymphomas. In-situ RNA hybridization studies indicated that diffuse neoplastic lymphocytes from the cervical lymph node contained abundant viral nucleic acid, while viral nucleic acid was not detectable in lymphocytes from the intestinal lymphoma lesion. The proviral long terminal repeat (LTR) was amplified and sequenced from multiple anatomic sites, and a common clone containing a single nucleotide polymorphism was determined to be defective in response to phorbol myristate acetate (PMA)-mediated promoter activation in a reporter gene assay. This assay revealed a previously unidentified PMA response element within the FIV U3 region 3’ to the TATA box. The possible implications of these results on FIV-lymphoma pathogenesis are discussed.

The nucleoside analog GS-441524 strongly inhibits feline infectious peritonitis (FIP) virus in tissue culture and experimental cat infection studies

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GS-441524 inhibited replication of serotype II FIP virus (FIPV) in CRFK cell cultures at an EC50 of approximately 1 uM and no toxicity at 100 uM.

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GS-441524 inhibited wildtype FIPV replication in macrophage cultures from ascitic fluid of two cats with naturally occurring FIP.

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GS-441525 is triphosphorylated by CRFK cells in vitro and PBMC in vivo.

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Pharmacokinetic studies in laboratory cats demonstrated effective blood levels over 24 h after a single dose of 5 mg/kg SC or IV.

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Severe experimental effusive FIP was successfully treated with 2 or 5 mg/kg GS-441524 SC q24 h for two weeks.

Feline infectious peritonitis (FIP) is a common and highly lethal coronavirus disease of domestic cats. Recent studies of diseases caused by several RNA viruses in people and other species indicate that antiviral therapy may be effective against FIP in cats. The small molecule nucleoside analog GS-441524 is a molecular precursor to a pharmacologically active nucleoside triphosphate molecule. These analogs act as an alternative substrate and RNA-chain terminator of viral RNA dependent RNA polymerase. We determined that GS-441524 was non-toxic in feline cells at concentrations as high as 100 uM and effectively inhibited FIPV replication in cultured CRFK cells and in naturally infected feline peritoneal macrophages at concentrations as low as 1 uM. We determined the pharmacokinetics of GS-441524 in cats in vivo and established a dosage that would sustain effective blood levels for 24 h. In an experimental FIPV infection of cats, GS-441524 treatment caused a rapid reversal of disease signs and return to normality with as little as two weeks of treatment in 10/10 cats and with no apparent toxicity.

Apical Elongation of Molar Teeth in Captive Microtus Voles

Molar apical elongation (MAE) was the leading cause for euthanasia or death in a captive breeding colony of endangered Amargosa voles ( Microtus californicus scirpensis). Clinical signs included ocular discharge, abnormal mastication, dyspnea, abnormal mentation, weight loss, and death. Although the severity varied, all molars in all quadrants were affected. When severe, the overgrown molar reserve crown and apex protruded into the nasal meatuses, the orbit, the calvarial vault and through the ventral margin of the mandible. Overall prevalence in the colony was 63% (92/146 voles) and increased to 77% in aged voles (>1 year). Mean age of onset was 5.3 months (1.7-11.2 months). Progression to extreme severity occurred over 1 to 3 months. Mean survival was 10.9 months (7.1-21.7 months). Histologically, the lesion was characterized by odontogenic hyperplasia and dysplasia. MAE was also documented in museum specimens of 2 other M. californicus subspecies ( M. californicus californicus, M. californicus vallicola) and 3 other Microtus species ( M. montanus, M. pennsylvanicus, M. socialis). In the M. californicus californicus collection, overall prevalence was 35.1% (129/368 skulls) and increased to 77.3% in aged voles (>1 year). A probable genetic influence was identified in the museum collection of M. californicus californicus. The etiopathogenesis of MAE is likely multifactorial, due to (1) inherent continuous odontogenic proliferation, (2) inadequate occlusal attrition, and (3) possible heritable disease susceptibility. In captivity, dietary or other management of occlusal attrition to prevent or delay MAE is a fundamental concern.

Multifocal discrete osteolysis in a horse with silicate associated osteoporosis

Silicate associated osteoporosis (SAO) was diagnosed post mortem in an adult horse with the shortest documented exposure to cytotoxic silicates of 2 years. The horse was evaluated for a 6-months history of progressive back tenderness and acute onset of lameness. The horse had a marked (4/5) [American Association of Equine Practitioners scale] left forelimb lameness, moderate (2/5) hindlimb ataxia and weakness, and cervical pain upon palpation. Physical examination did not reveal clinical skeletal deformities or respiratory compromise. Radiographs revealed widespread, discrete, sharply delineated, osteolytic lesions in the skull, vertebral column, ribs, scapulae and middle phalanx (P2) of the left forelimb and a diffuse bronchointerstitial lung pattern. The presumptive clinical diagnosis was widespread, metastatic osteolytic neoplasia. Due to the poor quality of life and grave prognosis, the horse was humanely euthanised. Post mortem examination revealed pulmonary silicosis in the lungs and hilar lymph nodes and osteolytic lesions with numerous, large osteoclasts and disorganised bone remodeling both consistent with SAO. SAO should be included as a differential diagnosis for horses with widespread, multifocal, discrete osteolysis and history of exposure to endemic regions with possible cytotoxic silicate inhalation. Exposure time of 2 years is potentially sufficient to develop SAO.

Evaluation of P16 expression in canine appendicular osteosarcoma

BACKGROUND

Osteosarcoma (OSA) is a common malignant bone tumor of large breed dogs that occurs at predictable anatomic sites. At the time of initial diagnosis, most affected dogs have occult pulmonary metastases. Even with aggressive surgical treatment combined with chemotherapy, the majority of dogs diagnosed with OSA live less than 1 year from the time of diagnosis. The ability to identify canine OSA cases most responsive to treatment is needed. In humans, OSA is also an aggressive tumor that is histologically and molecularly similar to canine OSA. The expression of the tumor suppressor gene product P16 by human OSA tissue has been linked to a favorable response to chemotherapy.

RESULTS

We identified an antibody that binds canine P16 and developed a canine OSA tissue microarray in order to test the hypothesis that P16 expression by canine OSA tissue is predictive of clinical outcome following amputation and chemotherapy. Although statistical significance was not reached, a trend was identified between the lack of canine OSA P16 expression and a shorter disease free interval.

CONCLUSIONS

The identification of a molecular marker for canine OSA is an important goal and the results reported here justify a larger study.

Implant-associated neoplasia in dogs: 16 cases (1983-2013)

OBJECTIVE

To characterize clinical and pathological features of implant-associated neoplasms in dogs.

DESIGN

Retrospective case-control study.

ANIMALS

16 dogs with implant-associated neoplasia and 32 control dogs with osteosarcoma without implants. Procedures: Medical records of dogs with tumors associated with metallic implants (cases) treated between 1983 and 2013 were reviewed. Two dogs with naturally occurring osteosarcoma (controls) were matched to each case on the basis of tumor location, age, and sex.

RESULTS

Median time from implant placement to diagnosis of neoplasia was 5.5 years (range, 9 months to 10 years). Pelvic limbs were most frequently affected, including the tibia (8/16) and femur (5/16), with 1 neoplasm involving both the femur and pelvis. Implant: associated tumors most commonly affected the diaphysis (15/16), with osteosarcomas significantly more likely to involve the long bone diaphysis in case dogs than in control dogs with naturally occurring osteosarcomas. Osteosarcoma was the most common tumor, accounting for 13 of 16 implant-associated tumors. For 7 of these osteosarcoma cases, review of histopathology results enabled subclassification into osteoblastic nonproductive (n = 3), chondroblastic (2), osteoblastic productive (1), and fibroblastic (1) groups. Three case dogs had a diagnosis of histiocytic sarcoma, fibrosarcoma, and spindle cell sarcoma.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of this study highlighted important anatomic differences between spontaneous and implant-associated neoplasia in dogs.

Sequence Instability in the Proviral Long Terminal Repeat and gag Regions from Peripheral Blood and Tissue-Derived Leukocytes of FIV-Infected Cats during the Late Asymptomatic Phase

Feline immunodeficiency virus (FIV) infection results in viral persistence, a prolonged asymptomatic phase, and progressive immunopathology. During the asymptomatic phase, a cohort of experimentally FIV-infected cats exhibits features of viral latency in blood suggestive of inactive viral replication. We sought to investigate viral replication activity and genomic stability of the FIV proviral long terminal repeat (LTR) and the 5′ aspect of gag over time. FIV-infected cats during the asymptomatic phase demonstrated undetectable plasma FIV gag RNA transcripts and intermittent to undetectable blood-derived cell-associated FIV gag RNA. The LTR sequence demonstrated instability in blood-derived cells over time, in spite of low to undetectable viral replication. Sequence variation in the LTR was identified in CD4+ and CD21+ leukocytes from blood and surgically removed lymph nodes. Three single nucleotide polymorphisms (SNPs) in the LTR were commonly identified. Promoter functionality of a common LTR SNP and rare U3 mutation were examined by reporter gene assays and demonstrated either no change or increased basal FIV promoter function, respectively. In conclusion, this cohort of asymptomatic FIV-infected cats demonstrated instability of the LTR and 5’ gag sequences during the study period, in spite of undetectable plasma and rare to undetectable viral gag RNA, which suggests that blood may not accurately represent viral activity in asymptomatic FIV-infected cats.

Viral Reservoirs in Lymph Nodes of FIV-Infected Progressor and Long-Term Non-Progressor Cats during the Asymptomatic Phase

Background

Examination of a cohort of cats experimentally infected with feline immunodeficiency virus (FIV) for 5.75 years revealed detectable proviral DNA in peripheral blood mononuclear cells (PBMCs) harvested during the asymptomatic phase, undetectable plasma viral RNA (FIV gag), and rarely detectable cell-associated viral RNA. Despite apparent viral latency in peripheral CD4+ T cells, circulating CD4+ T cell numbers progressively declined in progressor animals. The aim of this study was to explore this dichotomy of peripheral blood viral latency in the face of progressive immunopathology. The viral replication status, cellular immunophenotypes, and histopathologic features were compared between popliteal lymph nodes (PLNs) and peripheral blood. Also, we identified and further characterized one of the FIV-infected cats identified as a long-term non-progressor (LTNP).

Results

PLN-derived leukocytes from FIV-infected cats during the chronic asymptomatic phase demonstrated active viral gag transcription and FIV protein translation as determined by real-time RT-PCR, Western blot and in situ immunohistochemistry, whereas viral RNA in blood leukocytes was either undetectable or intermittently detectable and viral protein was not detected. Active transcription of viral RNA was detectable in PLN-derived CD4+ and CD21+ leukocytes. Replication competent provirus was reactivated ex vivo from PLN-derived leukocytes from three of four FIV-infected cats. Progressor cats showed a persistent and dramatically decreased proportion and absolute count of CD4+ T cells in blood, and a decreased proportion of CD4+ T cells in PLNs. A single long-term non-progressor (LTNP) cat persistently demonstrated an absolute peripheral blood CD4+ T cell count indistinguishable from uninfected animals, a lower proviral load in unfractionated blood and PLN leukocytes, and very low amounts of viral RNA in the PLN.

Conclusion

Collectively our data indicates that PLNs harbor important reservoirs of ongoing viral replication during the asymptomatic phase of infection, in spite of undetectable viral activity in peripheral blood. A thorough understanding of tissue-based lentiviral reservoirs is fundamental to medical interventions to eliminate virus or prolong the asymptomatic phase of FIV infection.

Endoscopic treatment of an intrathoracic tracheal osteochondroma in a dog

CASE DESCRIPTION

A 1.5-year-old spayed female Bernese Mountain Dog was examined for a 6-month history of intermittent vomiting, regurgitation, wheezing, and coughing. Initially, a diagnosis of gastroesophageal reflux disease with secondary aspiration pneumonitis was made but clinical signs did not resolve with treatment.

CLINICAL FINDINGS

Thoracic and cervical radiography and CT revealed a sessile, irregularly marginated soft tissue opacity at the level of the fourth rib. Results of a CBC, serum biochemical analysis, and urinalysis were within reference limits. Results of abdominal ultrasonography were normal.

TREATMENT AND OUTCOME

Tracheoscopy revealed a firm, irregularly marginated mass apparently originating from the ventral aspect of the trachea, occluding approximately one-half of the tracheal lumen, and located 2 cm cranial to the carina. Cytologic and histopathologic examination of fine-needle aspirate and biopsy samples suggested a benign etiology; therefore, endoscopic minimally invasive laser and electrocautery resection of the mass was scheduled. A total IV anesthetic protocol was administered with an oxygen-air mixture used to decrease the risk of fire during tracheal surgery. The mass was successfully resected, and histopathologic examination confirmed a diagnosis of osteochondroma. Clinical signs resolved, and at follow-up 32 months later, no regrowth of the mass was evident.

CLINICAL RELEVANCE

Tracheoscopy-guided electrocautery and surgical diode laser resection was successful in removing an obstructive tracheal mass that was not resectable by means of a conventional open surgical approach. Minimally invasive procedures may decrease morbidity and mortality and improve outcome in appropriately selected small animal patients.

Nasal Cavity Masses Resembling Chondro-osseous Respiratory Epithelial Adenomatoid Hamartomas in 3 Dogs

Chondro-osseous respiratory epithelial adenomatoid hamartomas (COREAHs) are rare tumors in the nasal cavity of people, which have not been described in other species. COREAHs in people are minimally invasive and rarely recur following excision. Histologically, these tumors are composed of disorganized, mature, nasal turbinate tissue that is organized into polypoid growths. These growths are lined by respiratory epithelium, contain glandular elements, and are organized around central cores of chondro-osseous matrix. This report describes 3 cases of dogs with nasal tumors that have histomorphology similar to that of COREAH in people. The tumors were all identified within the nasal cavity and were associated with regional bony lysis of the turbinates and surrounding skull bones, a feature that has not been reported in COREAH in people. There was no evidence of metastasis or extension beyond the nasal cavity in any of the 3 cases.

Chytridiomycosis in dwarf African frogs Hymenochirus curtipes

Chytridiomycosis, resulting from an infection with the fungal agent Batrachochytrium dendrobatidis (Bd), has resulted in widespread population declines in both wild and captive amphibians. The dwarf African frog (DAF) Hymenochirus curtipes is native to central Africa and is commonly sold throughout North America as an aquarium pet species. Here we document fatal chytridiomycosis resulting from cutaneous Bd infections in DAF purchased directly from a pet store and from a historical lethal epizootic occurring at an aquaculture facility in central California, USA, more than 25 yr ago. Histological lesions and PCR-amplified sequence data were consistent with the etiology of Bd. The potential epidemiological relevance of this infection in DAF is discussed.

Osteonecrosis of the Jaws in Dogs in Previously Irradiated Fields: 13 Cases (1989-2014)

The aim of this report was to characterize osteonecrosis of the jaws (ONJ) in previously irradiated fields in dogs that underwent radiotherapy (RT) for oral tumors. Osteoradionecrosis of the jaw (ORNJ) was further defined as osteonecrosis in a previously irradiated field in the absence of a tumor. Thirteen dogs clinically diagnosed with 15 ONJ lesions were included in this retrospective case series. Medical records were reviewed for: breed, sex, weight, and age of the patient, tumor type, location in the oral cavity and size, location of the ONJ, time from RT to ONJ onset, known duration of the ONJ, and tumor presence. Where available, histological assessment of tissues obtained from the primary tumor, and tissues obtained from the ONJ lesion, was performed, and computed tomographic (CT) images and dental radiographs were reviewed. RT and other treatment details were also reviewed. Twelve dogs developed ONJ in the area of the previously irradiated tumor or the jaw closest to the irradiated mucosal tumor. Recurrence of neoplasia was evident at the time of ONJ diagnosis in five dogs. Time from RT start to ONJ onset varied from 2 to 44 months. In three cases, ORNJ developed after dental extractions in the irradiated field. Dental radiographs mostly revealed a moth-eaten pattern of bone loss, CT mostly revealed osteolysis, and histopathology was consistent with osteonecrosis. To conclude, development of ONJ/ORNJ following RT is a rare, but potentially fatal complication. Patients undergoing RT may benefit from a comprehensive oral and dental examination and treatment prior to RT.

Genetic variability and in vitro transcriptional permissibility of primary ovine beta-retrovirus promoter isolates

OBJECTIVE

To assess genomic sequence conservation and variation in the proviral promoter of enzootic nasal tumor virus (ENTV) and Jaagsiekte sheep retrovirus (JSRV) in tissue samples from 3 sheep with nasal adenocarcinoma associated with ENTV and 3 sheep with pulmonary adenocarcinoma associated with JSRV and to identify a cell culture system that supports transcriptional activity of the ENTV and JSRV viral promoters.

ANIMALS

6 adult sheep.

PROCEDURES

Standard PCR procedures for detection of the ENTV and JSRV long terminal repeat (LTR) promoter region were performed on samples from the 3 nasal adenocarcinomas and 3 pulmonary adenocarcinomas, respectively. The LTRs were cloned into shuttle vectors, amplified, sequenced, and analyzed. The cloned LTR regions were transferred into reporter plasmids and multiple human and ruminant cell lines, and primary cells were transfected with the promoter-reporter plasmids. The viral promoter activity was evaluated by use of an in vitro β-galactosidase reporter assay.

RESULTS

Each isolate had a unique nucleotide sequence. Single nucleotide polymorphisms were the most common LTR mutation and rarely occurred at transcription factor binding sites. Relative to ENTV, the JSRV promoter isolates had a conserved 66-bp U3 insertion, including the lung-specific transcription factor HNF-3β binding site. Among the cell lines used, human embryonic kidney (293T) and goat synovial membrane cells supported promoter transcription.

CONCLUSIONS AND CLINICAL RELEVANCE

The LTRs of ENTV and JSRV have extensive blocks of sequence conservation. Human 293T and goat synovial membrane cell lines may be suitable in vitro cell culture systems for further research of viral promoter functions.

Common and emerging infectious diseases in the animal shelter

The beneficial role that animal shelters play is unquestionable. An estimated 3 to 4 million animals are cared for or placed in homes each year, and most shelters promote public health and support responsible pet ownership. It is, nonetheless, inevitable that shelters are prime examples of anthropogenic biological instability: even well-run shelters often house transient, displaced, and mixed populations of animals. Many of these animals have received minimal to no prior health care, and some have a history of scavenging or predation to survive. Overcrowding and poor shelter conditions further magnify these inherent risks to create individual, intraspecies, and interspecies stress and provide an environment conducive to exposure to numerous potentially collaborative pathogens. All of these factors can contribute to the evolution and emergence of new pathogens or to alterations in virulence of endemic pathogens. While it is not possible to effectively anticipate the timing or the pathogen type in emergence events, their sites of origin are less enigmatic, and pathologists and diagnosticians who work with sheltered animal populations have recognized several such events in the past decade. This article first considers the contribution of the shelter environment to canine and feline disease. This is followed by summaries of recent research on the pathogenesis of common shelter pathogens, as well as research that has led to the discovery of novel or emerging diseases and the methods that are used for their diagnosis and discovery. For the infectious agents that commonly affect sheltered dogs and cats, including canine distemper virus, canine influenza virus, Streptococcus spp, parvoviruses, feline herpesvirus, feline caliciviruses, and feline infectious peritonitis virus, we present familiar as well as newly recognized lesions associated with infection. Preliminary studies on recently discovered viruses like canine circovirus, canine bocavirus, and feline norovirus indicate that these pathogens can cause or contribute to canine and feline disease.

Pharmacokinetics and pharmacodynamics of suberoylanilide hydroxamic acid in cats

Suberoylanilide hydroxamic acid (SAHA), or vorinostat, is a histone deacetylase inhibitor approved for use as chemotherapy for lymphoma in humans. The goal of this study was to establish pharmacological parameters of SAHA in cats. Our interest in treating cats with SAHA is twofold: as an anticancer chemotherapeutic and as antilatency therapy for feline retroviral infections. Relying solely on data from studies in other animals would be inappropriate as SAHA is partially metabolized by glucuronidation, which is absent in feline metabolism. SAHA was administered to cats intravenously (2 mg/kg) or orally (250 mg/m², ~17 mg/kg) in a cross-over study design. Clinically, SAHA was well tolerated at these dosages as no abnormalities were noted following administration. The pharmacokinetics of SAHA in cats was found to be similar to that of dogs, but the overall serum drug exposure was much less than that of humans at an equivalent dose. The pharmacodynamic effect of an increase in acetylated histone proteins in blood was detected after both routes of administration. An increased oral dose of 60 mg SAHA/kg administered to one animal resulted in a surprisingly modest increase in peak drug concentration, suggesting possible saturation of absorption kinetics. This study provides a foundation for future studies of the clinical efficacy of SAHA in treating feline disease.

Oral papillary squamous cell carcinoma in twelve dogs

Papillary squamous cell carcinoma (PSCC) is a distinct histological subtype of oral squamous cell carcinoma (SCC), described in both dogs and man. In dogs, PSCC has long been considered a malignant oral tumour of very young animals, but it has recently been reported to occur in adult dogs as well. The aim of this study was to describe the major clinicopathological characteristics of canine oral PSCC (COPSCC). Twelve dogs diagnosed with COPSCC were included in this retrospective study (1990-2012). The majority (75%) of the dogs were >6 years of age (median age 9 years). All tumours were derived from the gingiva of dentate jaws, with 66.7% affecting the rostral aspects of the jaws. The gross appearance of the lesions varied, with one having an intraosseous component only. The majority (91.7%) of the tumours were advanced lesions (T2 and T3), but no local or distant metastases were noted. Microscopically, two patterns were seen: (1) invasion of bone forming a cup-shaped indentation in the bone or a deeply cavitating cyst within the bone (cavitating pattern), (2) histologically malignant growth, but lack of apparent bone invasion (non-cavitating pattern). The microscopical appearance corresponded to imaging findings in a majority of cases, with cavitating forms presenting with a cyst-like pattern of bone loss or an expansile mass on imaging and non-cavitating forms showing an infiltrative pattern of bone destruction on imaging. These features suggest two distinct biological behaviours of COPSCC.

Sex differences in blood flow restricted isotonic knee extensions to fatigue

AIM

It has been shown that females have greater muscular endurance than males and that this advantage is eliminated when blood flow is restricted. It is unknown if sex differences in dynamic endurance exist during low-load blood flow restricted (BFR) resistance exercise. The purpose of this study was to investigate sex differences in quadriceps femoris fatigability during isotonic knee extension exercise coupled with a blood flow restriction.

METHODS

Ten males and ten females completed three sets of low-load isotonic knee extension exercises (20% of peak torque) to volitional failure under two conditions: blood flow restricted (BFR) and non-restricted free flow (FF). The number of repetitions, exercise volume, post-exercise strength loss and surface electromyography (EMG) were measured.

RESULTS

Females performed more repetitions than males in the FF (252±37 vs. 112±17 repetitions; P<0.01) and BFR conditions (165±29 vs. 79±8 repetitions; P<0.01). Both sexes performed ~30% fewer repetitions during the BFR condition. MVC torque decreased approximately 37% following both conditions (P<0.01) and EMG activity increased (P<0.05) during the exercise bouts.

CONCLUSION

Similar fatigue characteristics were evident in FF and BFR conditions for both sexes, and females demonstrated greater endurance, as determined by the number of repetitions completed, in both conditions. It may be beneficial to increase the relative exercise load for females in order to decrease the time under BFR.

Feline immunodeficiency virus latency

Despite highly effective anti-retroviral therapy, HIV is thought to persist in patients within long-lived cellular reservoirs in the form of a transcriptionally inactive (latent) integrated provirus. Lentiviral latency has therefore come to the forefront of the discussion on the possibility of a cure for HIV infection in humans. Animal models of lentiviral latency provide an essential tool to study mechanisms of latency and therapeutic manipulation. Of the three animal models that have been described, the feline immunodeficiency virus (FIV)-infected cat is the most recent and least characterized. However, several aspects of this model make it attractive for latency research, and it may be complementary to other model systems. This article reviews what is known about FIV latency and chronic FIV infection and how it compares with that of other lentiviruses. It thereby offers a framework for the usefulness of this model in future research aimed at lentiviral eradication.

Pharmacologic reactivation of latent feline immunodeficiency virus ex vivo in peripheral CD4+ T-lymphocytes

FIV establishes a latent infection in peripheral CD4+ T-cells, and the latent FIV promoter is associated with deacetylated, methylated histones, consistent with a restrictive chromatin structure. Here we explored the use of 5 histone-modifying agents - 4 histone deacetylase inhibitors (HDACi) and 1 histone methyltransferase inhibitor (HMTi) - to reactivate latent FIV ex vivo. All compounds tested were able to alter histone lysine residue modifications in feline cells, both globally and at the FIV promoter locally. When latently FIV-infected peripheral CD4+ T-cells were cultured ex vivo in the presence of these inhibitors, viral transcription was significantly activated relative to no treatment controls. Transcriptional reactivation of virus mediated by the HDACi suberoylanilide hydroxamic acid (SAHA) was dose-dependent, detected after as little as 1h of exposure, and resulted in virion formation as evidenced by supernatant reverse transcriptase activity. A synergistic effect was not found when SAHA was combined with HMTi under the conditions tested. At low therapeutically relevant concentrations in primary feline PBMC, SAHA was found to be minimally cytotoxic and non-immune activating. HDACi and HMTi can reactivate latent FIV ex vivo, and SAHA, also known as the anticancer drug Vorinostat, in particular is a promising candidate for in vivo use because of its efficacy, potency, and relative safety. Use of the FIV/cat model of lentiviral latency to explore in vivo treatment with SAHA and other anti-latency therapeutics will allow investigations that are either ethically or logistically not addressable in patients persistently infected with human immunodeficiency virus (HIV-1).

Gastric cryptosporidiosis in freshwater angelfish (Pterophyllum scalare)

A freshwater angelfish (Pterophyllum scalare) hatchery experienced variable levels of emaciation, poor growth rates, swollen coelomic cavities, anorexia, listlessness, and increased mortality within their fish. Multiple chemotherapeutic trials had been attempted without success. In affected fish, large numbers of protozoa were identified both histologically and ultrastructurally associated with the gastric mucosa. The youngest cohort of parasitized fish was the most severely affected and demonstrated the greatest morbidity and mortality. The protozoa were morphologically most consistent with Cryptosporidium. All of the protozoan life stages were identified ultrastructurally and protozoal genomic DNA was isolated from parasitized tissue viscera and sequenced. Histological, ultrastructural, genetic, and phylogenetic analyses confirmed this protozoal organism to be a novel species of Cryptosporidium.

Ganglioneuroma of the brachial plexus in two cockatiels (Nymphicus hollandicus)

Ganglioneuroma involving the brachial plexus, paraspinal ganglia, and cervical-thoracic spinal cord was diagnosed in 2 adult cockatiels (Nymphicus hollandicus). Both birds had a chronic 1-year history of ataxia and perching difficulty. At necropsy, each bird had a unilateral, firm, gelatinous white to tan multilobular mass at the thoracic inlet expanding and partially obliterating the brachial plexus and cervical spinal cord. Histologically, the masses were characterized by a locally infiltrative neoplasm comprised of spindloid cells forming streams and sheets with interspersed distinct neuron cell bodies consistent with ganglion cells. The spindloid cell population was immunohistochemically positive for neurofilament protein in one of the birds.