Intrahepatic mucinous cholangiocarcinoma with recurrent colic in a horse: case report and literature review of cholangiocarcinoma in horses.

A 17-y-old Arabian mare was presented to the Auburn Large Animal Veterinary Teaching Hospital with a long-term history of intermittent mild recurrent colic that responded to medical treatment. CBC revealed mild lymphopenia; serum biochemistry findings were of increased gamma-glutamyl transferase and creatine kinase activities, hyperferremia, hyperglycemia, hypomagnesemia, and hypokalemia. Abdominocentesis was compatible with low-protein transudate. Due to the progression and duration of clinical signs, the owner elected euthanasia. Postmortem examination and histopathology confirmed a cholangiocarcinoma. The neoplastic cells were arranged in large cysts containing lakes of mucin that comprised 90% of the tumor volume; thus, a mucinous variant was determined. The neoplastic cells had strong cytoplasmic immunolabeling for cytokeratin 19 and lacked immunolabeling for hepatocyte paraffin 1, supporting bile duct origin. Cholangiocarcinomas are infrequent tumors in horses with nonspecific and slow progressive clinical signs, including recurrent colic. Mucinous cholangiocarcinomas are seldom reported in veterinary medicine and, to our knowledge, have not been reported previously in horses.

Hepatic Perisinusoidal Myofibroblast Proliferation and Systemic Inflammatory Response Precedes Sep/Tox Hepatitis in Broilers.

Septicemia-toxemia (sep/tox) falls under U.S. Department of Agriculture (USDA) food safety Category 1 and is the most common and economically significant cause of broiler carcass condemnations. Hepatic lesions are considered a possible consequence of septicemia and associated bacterial contamination of the carcass. Thus, these lesions are considered an indicator of sep/tox (sep/tox hepatitis). This study was undertaken to analyze the histologic lesions preceding grossly visible liver lesions leading to condemnation because of sep/tox at the processing plant. Livers from carcasses of broilers condemned by USDA inspectors for sep/tox were used to establish microscopic and gross criteria of end-stage sep/tox hepatitis. Following the characterization of sep/tox hepatitis, broilers from a farm with a history of sep/tox condemnations were submitted for postmortem examination and bacteriologic investigation at four intervals during the final 20 days of production. Five healthy and five clinically ill chickens were submitted from four houses at 18, 25, 32, and 38 days of production (160 total). Microscopic lesions representing hepatic perisinusoidal myofibroblast proliferation (HPMP), periportal extramedullary granulopoiesis (PEMG), splenic follicular histiocytosis, and bone marrow cellularity (BMC) were graded subjectively for each bird, and subjective grading was evaluated with digital quantitative techniques. Perisinusoidal hepatic stellate cell morphology and progressive transformation of these cells into myofibroblasts was confirmed by immunohistochemistry for smooth muscle actin and desmin. Aerobic cultures of livers and gall bladders from sep/tox birds yielded no growth of bacteria associated with septicemia. Mild to severe HPMP was observed in all age groups, representing 28% of examined birds. Increases in inflammatory cells observed by PEMG and BMC were positively correlated with progressive HPMP and end-stage sep/tox hepatitis in broiler chickens.

Artículo regular­Proliferación de miofibroblastos perisinusoidales hepáticos y respuesta inflamatoria sistémica que precede a la hepatitis por septicemia y toxemia (sep/tox) en pollos de engorde. La septicemia-toxemia (sep/tox) se incluye en la Categoría 1 de seguridad alimentaria del Departamento de Agricultura de los Estados Unidos. (USDA) y es la causa más común y económicamente significativa de decomisos de canales de pollos de engorde. Las lesiones hepáticas se consideran una posible consecuencia de la septicemia y de la contaminación bacteriana asociada con la canal. Por lo tanto, estas lesiones se consideran un indicador de septicemia/toxemia (hepatitis sep/tox). Este estudio se llevó a cabo para analizar las lesiones histológicas que preceden a las lesiones hepáticas muy visibles que conducen a los decomisos debido a septicemia/toxemia en la planta de procesamiento. Se utilizaron hígados de canales de pollos de engorde decomisados por los inspectores del USDA por septicemia/toxemia para establecer criterios microscópicos y generales de hepatitis en etapa terminal de la septicemia/toxemia. Después de la caracterización de la hepatitis por septicemia/toxemia, los pollos de engorde de una granja con un historial de decomisos por septicemia/toxemia se sometieron a examen post mortem e investigación bacteriológica en cuatro intervalos durante los últimos 20 días de producción. Se enviaron cinco pollos sanos y cinco clínicamente enfermos de cuatro casetas a los 18, 25, 32 y 38 días de producción (160 en total). Las lesiones microscópicas que representan la proliferación de miofibroblastos perisinusoidales hepáticos (HPMP), la granulopoyesis extramedular periportal (PEMG), la histocitosis folicular esplénica y la celularidad de la médula ósea (BMC) se clasificaron subjetivamente para cada ave, y la clasificación subjetiva se evaluó con técnicas cuantitativas digitales. La morfología de las células estrelladas hepáticas perisinusoidales y la transformación progresiva de estas células en miofibroblastos se confirmó mediante inmunohistoquímica para actina y desmina del músculo liso. Los cultivos aeróbicos de hígados y vesícula biliar de aves con septicemia/toxemia no produjeron crecimiento de bacterias asociadas con la septicemia. Se observó proliferación de miofibroblastos perisinusoidales hepáticos de leve a severa en todos los grupos de edad, lo que representa el 28% de las aves examinadas. Los aumentos en las células inflamatorias observados por granulopoyesis extramedular periportal y celularidad de la médula ósea se correlacionaron positivamente con proliferación progresiva de miofibroblastos perisinusoidales hepáticos y con hepatitis por septicemia/toxemia en etapa terminal en pollos de engorde.

Key Characteristics of Human Hepatotoxicants as a Basis for Identification and Characterization of the Causes of Liver Toxicity.

Hazard identification regarding adverse effects on the liver is a critical step in safety evaluations of drugs and other chemicals. Current testing paradigms for hepatotoxicity rely heavily on preclinical studies in animals and human data (epidemiology and clinical trials). Mechanistic understanding of the molecular and cellular pathways that may cause or exacerbate hepatotoxicity is well advanced and holds promise for identification of hepatotoxicants. One of the challenges in translating mechanistic evidence into robust decisions about potential hepatotoxicity is the lack of a systematic approach to integrate these data to help identify liver toxicity hazards. Recently, marked improvements were achieved in the practice of hazard identification of carcinogens, female and male reproductive toxicants, and endocrine disrupting chemicals using the key characteristics approach. Here, we describe the methods by which key characteristics of human hepatotoxicants were identified and provide examples for how they could be used to systematically identify, organize, and use mechanistic data when identifying hepatotoxicants.

Nonclassified Lymphoma as a Cause of Radial Nerve Paralysis in a Horse.

A 4-year-old American Quarter Horse gelding was evaluated for acute non-weight-bearing lameness of the right thoracic limb with swelling in the right shoulder region. Physical examination revealed radial nerve paralysis of unknown etiology. The primary differential diagnosis was musculoskeletal trauma. Ultrasonography of the right shoulder region identified a heterogeneous mass that extended from the point of the shoulder to the thoracic inlet. Cytologic analysis of fluid collected by fine needle aspirate of the mass was consistent with large cell lymphoma. Based on the cytological findings, locally invasive neoplasia was diagnosed and considered the likely cause of the radial nerve paralysis. Because of the poor prognosis, the horse was euthanized, and postmortem examination confirmed the diagnosis of a nonclassified large cell lymphoma that extended from the deep tissues of the right pectoral muscle group into the thoracic inlet and pleural cavity, as well as the right brachial plexus. The mass in the region of the brachial plexus encompassed and mechanically compressed all of the nerves within the area, resulting in the clinical sign of radial nerve paralysis. Although neoplasia as a cause of radial nerve paralysis is rare, it should be considered as a differential diagnosis, regardless of age.

Tensile strength and early healing of self-locking and surgeon's knots.

OBJECTIVE: To compare the biomechanical properties and healing of ventral midline celiotomies (VMC) closed with a self-locking knot combination and forwarder start and Aberdeen end (F-A) vs a traditional knot combination and surgeon's start and end (S-S). STUDY DESIGN: In vivo, experimental. ANIMALS: Twenty-one horses. METHODS: Fourteen horses underwent VMC, which was closed with either an F-A (n = 7) or an S-S (n = 7) knot combination. Incisions were subjectively graded by masked evaluators for dehiscence, edema, and drainage. Biomechanical testing was performed on three abdominal segments, and histology was performed on one segment from each animal after humane euthanasia 10 days post-VMC. The abdominal wall of control horses (n = 7, no celiotomy) was collected for biomechanical testing. RESULTS: Forwarder start and Aberdeen end and S-S horses had less tensile strength compared with control horses (P ≤ .001). No differences were detected between treatment groups for any variable evaluated, including tensile strength (P = .975), location of failure (P = .240), and histologic healing at the knot (P = .600). CONCLUSION: Closure of VMC with self-locking knots resulted in biomechanical and healing features similar to those with a traditional closure technique, with neither restoring the tensile strength of the linea alba. CLINICAL SIGNIFICANCE: Results of this study provide evidence to support a clinical trial to evaluate long-term performance of the F-A self-locking knot closure in horses.

Comparison of microbiota, antimicrobial resistance genes and mobile genetic elements in flies and the feces of sympatric animals.

Flies are well-known vectors of bacterial pathogens, but there are little data on their role in spreading microbial community and antimicrobial resistance. In this study, we compared the bacterial community, antimicrobial resistance genes (ARGs) and mobile genetic elements (MGEs) in flies with those in the feces of sympatric animals. A 16S rRNA-based microbial analysis identified 23 bacterial phyla in fecal samples and 25 phyla in flies; all the phyla identified in the fecal samples were also found in the flies. Bray-Curtis dissimilarity analysis showed that the microbiota of the flies were more similar to the microbiota of the feces of their sympatric animals than those of the feces from the three other animal species studied. The qPCR array amplified 276 ARGs/MGEs in fecal samples, and 216 ARGs/MGEs in the flies, while 198 of these genes were identified in both flies and feces. Long-term studies with larger sample numbers from more geospatially distinct populations and infection trials are indicated to further evaluate the possibility of flies as sentinels for antimicrobial resistance.

Expression of Hematopoietic Stem and Endothelial Cell Markers in Canine Hemangiosarcoma.

Several chemicals and pharmaceuticals increase the incidence of hemangiosarcomas (HSAs) in mice, but the relevance to humans is uncertain. Recently, canine HSAs were identified as a powerful tool for investigating the pathogenesis of human HSAs. To characterize the cellular phenotype of canine HSAs, we evaluated immunoreactivity and/or messenger RNA (mRNA) expression of markers for hematopoietic stem cells (HSCs), endothelial cells (ECs), a tumor suppressor protein, and a myeloid marker in canine HSAs. Neoplastic canine cells expressed EC markers and a myeloid marker, but expressed HSC markers less consistently. The canine tumor expression results were then compared to previously published immunoreactivity results for these markers in human and mouse HSAs. There are 2 noteworthy differences across species: (1) most human HSAs had HSC marker expression, indicating that they were comprised of tumor cells that were less differentiated than those in canine and mouse tumors; and (2) human and canine HSAs expressed a late-stage EC maturation marker, whereas mouse HSAs were negative, suggesting that human and canine tumors may retain greater differentiation potential than mouse tumors. These results indicate that HSA development is variable across species and that caution is necessary when discussing translation of carcinogenic risk from animal models to humans.

Phage constructs targeting gonadotropin-releasing hormone for fertility control: evaluation in cats.

OBJECTIVES: Phage-gonadotropin-releasing hormone (GnRH) constructs with potential contraceptive properties were generated in our previous study via selection from a phage display library using neutralizing GnRH antibodies as selection targets. In mice, these constructs invoked the production of antibodies against GnRH and suppressed serum testosterone. The goal of this study was to evaluate this vaccine against GnRH for its potential to suppress reproductive characteristics in cats. METHODS: Sexually mature male cats were injected with a phage-GnRH vaccine using the following treatment groups: (1) single phage-GnRH vaccine with adjuvant; (2) phage-GnRH vaccine without adjuvant and half-dose booster 1 month later; or (3) phage-GnRH vaccine with adjuvant and two half-dose boosters with adjuvant 3 and 6 months later. Anti-GnRH antibodies and serum testosterone, testicular volume and sperm characteristics were evaluated monthly for 7-9 months. RESULTS: All cats developed anti-GnRH antibodies following immunization. Serum antibody titers increased significantly after booster immunizations. In group 3, serum testosterone was suppressed 8 months after primary immunization. Total testicular volume decreased in group 1 by 24-42% and in group 3 by 15-36% at 7 months after immunization, indicating potential gonadal atrophy. Vacuolation of epididymides was observed histologically. Although all cats produced sperm at the conclusion of the study, normal morphology was decreased as much as 38%. Phage alone produced no local or systemic reactions. Immunization of phage with AdjuVac produced unacceptable injection site reactions. CONCLUSIONS AND RELEVANCE: Our phage-based vaccine against GnRH demonstrated a potential for fertility impairment in cats. Future research is required to optimize vaccine regimens and identify animal age groups most responsive to the vaccine. If permanent contraception (highly desirable in feral and shelter cats) cannot be achieved, the vaccine has a potential use in zoo animals or pets where multiple administrations are more practical and/or reversible infertility is desirable.

Multidrug-Resistant Escherichia coli, Klebsiella pneumoniae and Staphylococcus spp. in Houseflies and Blowflies from Farms and Their Environmental Settings.

Background: Antimicrobial resistance is rising globally at an alarming rate. While multiple active surveillance programs have been established to monitor the antimicrobial resistance, studies on the environmental link to antimicrobial spread are lacking. Methods: A total of 493 flies were trapped from a dairy unit, a dog kennel, a poultry farm, a beef cattle unit, an urban trash facility and an urban downtown area to isolate Escherichia coli, Klebsiella pneumoniae and Staphylococcus spp. for antimicrobial susceptibility testing and molecular characterization. Results: E. coli, K. pneumoniae and coagulase-negative Staphylococcus were recovered from 43.9%, 15.5% and 66.2% of the houseflies, and 26.0%, 19.2%, 37.0% of the blowflies, respectively. In total, 35.3% of flies were found to harbor antimicrobial-resistant bacteria and 9.0% contained multidrug-resistant isolates. Three Staphylococcus aureus isolates were recovered from blowflies while three extended spectrum beta lactamase (ESBL)-carrying E. coli and one ESBL-carrying K. pneumoniae were isolated from houseflies. Whole genome sequencing identified the antimicrobial resistance genes blaCMY-2 and blaCTXM-1 as ESBLs. Conclusion: Taken together, our data indicate that flies can be used as indicators for environmental contamination of antimicrobial resistance. More extensive studies are warranted to explore the sentinel role of flies for antimicrobial resistance.

Dimethyl fumarate abrogates dust mite-induced allergic asthma by altering dendritic cell function.

INTRODUCTION: Allergic asthma is the most common inflammatory disease of upper airways. Airway dendritic cells (DCs) are key antigen presenting cells that regulate T helper 2 (Th2)-dependent allergic inflammation. Recent studies have shown critical role of airway DCs in the induction of Th2-mediated allergic inflammation and are attractive therapeutic targets in asthma. However, molecular signaling mechanism that regulate DCs function to Th2 immune responses are poorly understood. Here we aim to evaluate the immunomodulatory effect of dimethyl fumarate (DMF), an FDA approved small molecule drug, in the house dust mite (HDM)-induced experimental model of allergic asthma. METHODS: DMF was administered intranasally in the challenge period of HDM-induced murine model of experimental asthma. Airway inflammation, airway hyperreactivity, Th2/Th1 cytokine were assessed. The effect of DMF on DC function was further evaluated by adoptive transfer of HDM-pulsed DMF treated DCs to wild-type naïve mice. RESULTS: DMF treatment significantly reduced HDM-induced airway inflammation, mucous cell metaplasia, and airway hyperactivity to inhaled methacholine. Mechanistically, DMF interferes with the migration of lung DCs to draining mediastinal lymph nodes, thereby attenuates the induction of allergic sensitization and Th2 immune response. Notably, adoptive transfer of DMF treated DCs to naïve mice with HDM challenge similarly reduces the features of allergic asthma. CONCLUSION: This identifies a novel function of DMF on DC-mediated adaptive immune responses in the setting of HDM-induced airway inflammation. Taken together, our results offer a mechanistic rationale for DMF use to target DCs in local lung environment as antiasthmatic therapy.

DNA Vaccine Targeting Gonadotropin-Releasing Hormone Receptor and Its Application in Animal Contraception.

Overpopulation of free-roaming and wildlife animals negatively affects economy and public health in many parts of the world. Contraceptive vaccines are viewed as a valuable option for reducing numbers of unwanted animals. This study develops vaccines for potential use in animal contraception exploiting a DNA platform. Objectives of the study were to generate DNA constructs directed against gonadotropin-releasing hormone receptor (GnRHR), a crucial molecular player in animal reproduction, and characterize them for ability to promote immune responses and suppression of reproductive parameters in vivo. DNA constructs were created to encode for a recombinant protein composed of two domains: GnRHR, the target antigen, and ubiquitin (Ub), a support protein. Ub-GnRHR constructs administered intramuscularly or intradermally or containing different promoters were compared. CMV and EF1α promoters were shown to be superior to CAG. In fertility trials, mice immunized intradermally with Ub-GnRHR construct driven by EF1α had a significantly lower number of fetuses. Importantly, the impaired fertility was achieved with a single DNA immunization and without the use of adjuvants. The study demonstrated for the first time that targeting the GnRH receptor with DNA-based vaccines could be a viable option for animal contraception.

Housefly (Musca domestica) and Blow Fly (Protophormia terraenovae) as Vectors of Bacteria Carrying Colistin Resistance Genes.

Flies have the capacity to transfer pathogens between different environments, acting as one of the most important vectors of human diseases worldwide. In this study, we trapped flies on a university campus and tested them for mobile resistance genes against colistin, a last-resort antibiotic in human medicine for treating clinical infections caused by multidrug-resistant Gram-negative bacteria. Quantitative PCR assays we developed showed that 34.1% of Musca domestica (86/252) and 51.1% of Protophormia terraenovae (23/45) isolates were positive for the mcr-1 gene, 1.2% of M. domestica (3/252) and 2.2% of P. terraenovae (2.2%, 1/45) isolates were positive for mcr-2, and 5.2% of M. domestica (13/252) and 44.4% of P. terraenovae (20/45) isolates were positive for mcr-3 Overall, 4.8% (9/189) of bacteria isolated from the flies were positive for the mcr-1 gene (Escherichia coli: 8.3%, 4/48; Enterobacter cloacae: 12.5%, 1/8; Providencia alcalifaciens: 11.8%, 2/17; Providencia stuartii: 4.9%, 2/41), while none were positive for mcr-2 and mcr-3 Four mcr-1-positive isolates (two P. stuartii and two P. alcalifaciens) from blow flies trapped near a dumpster had a MIC for colistin above 4 mg/ml. This study reports mcr-1 carriage in Providencia spp. and detection of mcr-2 and mcr-3 after their initial identification in Belgium and China, respectively. This study suggests that flies might contribute significantly to the dissemination of bacteria, carrying these genes into a large variety of ecological niches. Further studies are warranted to explore the roles that flies might play in the spread of colistin resistance genes.IMPORTANCE Antimicrobial resistance is recognized as one of the most serious global threats to human health. An option for treatment of the Gram-negative ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) bacteria with multiple drug resistance was the reintroduction of the older antibiotic colistin. However, a mobile colistin resistance gene (mcr-1) has recently been found to occur widely; very recently, two other colistin resistance genes (mcr-2 and mcr-3) have been identified in Belgium and China, respectively. In this study, we report the presence of colistin resistance genes in flies. This study also reports the carriage of colistin resistance genes in the genus Providencia and detection of mcr-2 and mcr-3 after their initial identification. This study will stimulate more in-depth studies to fully elucidate the transmission mechanisms of the colistin resistance genes and their interaction.

Effect of heartworm disease and heartworm-associated respiratory disease (HARD) on the right ventricle of cats.

BACKGROUND: Dirofilaria immitis infection occurs in dogs and cats, both of which species are clinically affected by mature adult infections. Cats are uniquely affected by immature-adult infections with an inflammatory pulmonary disease called Heartworm-Associated Respiratory Disease (HARD). D. immitis infection causes pulmonary parenchymal and vascular pathology in the dog and cat. Dogs develop pulmonary hypertension and cor pulmonale, whereas the development of pulmonary hypertension is rare in the cat. D. immitis infection in the dog causes alteration of the right ventricular (RV) extracellular matrix, including a decrease in myocardial collagen. In this study, the RV myocardial changes of cats infected with adult and immature-adult D. immitis were assessed. METHODS: The cardiopulmonary systems of six groups of SPF cats (n = 9-10 per group) were examined 8 or 18 months after infection with L3 D. immitis. Two groups were untreated and allowed to develop adult HW; two groups were treated with ivermectin starting 3 months post infection, thus allowing HARD but no mature adult heartworms; and two groups were treated with selamectin beginning 1 month post infection, preventing development of L5 or adult heartworms. A group of specific pathogen free (SPF) normal cats was utilized as a negative control (n = 12). Lung pathologic lesions were objectively assessed, and both RV and left ventricular (LV) weights were obtained to calculate an RV/LV ratio. Intramural RV myocardial collagen content was quantitatively assessed. RESULTS: RV/LV weight ratios were not different between groups. Negative control cats had significantly greater RV collagen content than all other affected groups (P = 0.032). Analysis of the RV/LV ratios and collagen content revealed no significant relationship (r = 0.03, P = 0.723, respectively). Collagen content had a modest, but significant, negative correlation, however, with both pulmonary vascular pathology (r = -0.25, P = 0.032) as well as the total pulmonary parenchymal and vascular pathology (r = -0.26, P = 0.025). CONCLUSIONS: Cats infected with mature and immature D. immitis did not develop RV hypertrophy but did demonstrate loss of RV myocardial collagen content. The collagen loss was present at 8 and 18 months after infection in all infected cats. This loss of RV myocardial collagen was correlated with the severity of pulmonary parenchymal and vascular pathology.

Heartworm-associated respiratory disease (HARD) induced by immature adult Dirofilaria immitis in cats.

BACKGROUND: A controlled, blind research study was conducted to define the initial inflammatory response and lung damage associated with the death of immature adult Dirofilaria immitis in cats as compared with cats developing adult heartworm infections and cats on preventive medication. METHODS: Three groups of cats were utilized, 10 per group. All cats were infected with 100 third-stage (L3) larvae by subcutaneous injection. Group A cats were treated topically with selamectin (Revolution®; Zoetis) per label directions at 28 days post infection (PI) and once monthly for 8 months. Group B cats were treated orally with ivermectin (Ivomec®; Merial) at 150 µg/kg at 70 days PI, then every 2 weeks for 5 months. Group C cats were untreated PI. At baseline (Day 0) and on Days 70, 110, 168, and 240 PI, peripheral blood, serum, bronchial lavage, and thoracic radiographic images were collected on all cats. Upon completion of the study (Day 245), cats were euthanized and necropsies were conducted. RESULTS: Results were analyzed statistically between groups by ANOVA and by paired sample T testing for changes within the group over time. The selamectin-treated cats (Group A) did not develop radiographically evident changes throughout the study and were free of adult heartworms or worm fragments at necropsy. The heartworm life cycle was abbreviated with oral doses of ivermectin (Group B), shown by the absence of adult heartworms or worm fragments at necropsy. The early stage of immature adult worm in Group B cats, however, did induce severe pulmonary airway, interstitial, and arterial lung lesions, revealing that the abbreviated infection is a significant cause of respiratory pathology in cats. Cats in Groups B and C could not be differentiated based on radiographic changes, serologic antibody titers, complete blood count, or bronchoalveolar lavage cytology at any time point throughout the study. Eighty percent of cats in Group A and 100% of cats in Groups B and C became heartworm antibody positive at some time point post infection. CONCLUSIONS: The clinical implications of this study are that cats that become infected with immature adult heartworms may not develop fully mature heartworms and are only transiently heartworm antibody positive, but do develop Heartworm-Associated Respiratory Disease (HARD).

The progression of heartworm associated respiratory disease (HARD) in SPF cats 18 months after Dirofilaria immitis infection.

BACKGROUND: Heartworm-associated respiratory disease (HARD) in cats is induced by the arrival and death of immature adult Dirofilaria immitis in the pulmonary system and is indistinguishable from mature adult heartworm infection. METHODS: A controlled, blind research study investigated the long-term (18 months post infection, PI) consequences of the inflammatory response associated with the death of immature adult heartworms in cats. Three groups of cats, 10 per group, were infected with 100 third-stage (L3) larvae by subcutaneous injection. Group A cats were treated with selamectin (Revolution®; Zoetis) per label directions at 28 days PI and once monthly for 17 months. Group B cats were treated orally with ivermectin (Ivomec®; Merial) at 150 µg/kg) at 70 days PI, then every 2 weeks for 15 months. Group C cats were untreated PI. At baseline (Day 0) and on Days 70, 110, 168, 240, 309, 380, and 505 PI, peripheral blood, serum, bronchial lavage, and thoracic radiographic images were collected. RESULTS: The selamectin-treated cats (Group A) and ivermectin-treated cats (Group B) were free of heartworms or heartworm fragments at necropsy. All cats became heartworm antibody positive at some time point in the study except for one cat in Group A. Only cats in Group C (all with adult heartworms) were heartworm antigen positive. The heartworm antibody titer for Group B was highest on Days 110 to 168 and then decreased over time and 50% were serologically antibody negative on Day 240. Eosinophilic bronchoalveolar lavage (BAL) cytology and peripheral eosinophilia were most pronounced on Day 110 in all cats. Randomly distributed myofibrocytes in the lungs of some Group A cats suggest that precardiac larval stages were affecting the lungs. Radiographs in Group B cats demonstrated partial resolution of the initial HARD reaction but chronic myofibrocyte proliferation was histologically evident 18 months after infection. CONCLUSION: HARD was induced by immature adult worm infection with progressive improvement starting 6 to 8 months after infection but histologic lesions were evident in some cats 18 months after infection. The serologic antibody assay was negative in 50% of cats at 8 months and 100% of cats at 18 months post infection. Abnormal radiographic lung patterns continued in a subset of Group B cats for months after heartworm antibody serology and BAL cytology returned to normal.

Adding a Second Quinol to a Redox-Responsive MRI Contrast Agent Improves Its Relaxivity Response to H2O2.

The overproduction of reactive oxygen species has been linked to a wide array of health disorders. The ability to noninvasively monitor oxidative stress in vivo could provide substantial insight into the progression of these conditions and, in turn, could facilitate the development of better diagnosis and treatment options. A mononuclear Mn(II) complex with the redox-active ligand N,N'-bis(2,5-dihydroxybenzyl)-N,N'-bis(2-pyridinylmethyl)-1,2-ethanediamine (H4qtp2) was made and characterized. A previously prepared Mn(II) complex with a ligand containing a single quinol subunit was found to display a modest T1-derived relaxivity response to H2O2. The introduction of a second redox-active quinol both substantially improves the relaxivity response of the complex to H2O2 and reduces the cytotoxicity of the sensor but renders the complex more susceptible to transmetalation. The addition of H2O2 partially oxidizes the quinol subunits to para-quinones, concomitantly increasing the r1 from 5.46 mM-1 s-1 to 7.17 mM-1 s-1. The oxidation of the ligand enables more water molecules to coordinate to the metal ion, providing an explanation for the enhanced relaxivity. That the diquinol complex is only partially oxidized by H2O2 is attributed to its activity as an antioxidant; the complex can both catalytically degrade superoxide and serve as a hydrogen atom donor.

A comparison of microRNA expression profiles from splenic hemangiosarcoma, splenic nodular hyperplasia, and normal spleens of dogs.

BACKGROUND: Splenic masses are common in older dogs; yet diagnosis preceding splenectomy and histopathology remains elusive. MicroRNAs (miRNAs) are short, non-coding RNAs that play a role in post-transcriptional regulation, and differential expression of miRNAs between normal and tumor tissue has been used to diagnose neoplastic diseases. The objective of this study was to determine differential expression of miRNAs by use of RNA-sequencing in canine spleens that were histologically confirmed as hemangiosarcoma, nodular hyperplasia, or normal. RESULTS: Twenty-two miRNAs were found to be differentially expressed in hemangiosarcoma samples (4 between hemangiosarcoma and both nodular hyperplasia and normal spleen and 18 between hemangiosarcoma and normal spleen only). In particular, mir-26a, mir-126, mir-139, mir-140, mir-150, mir-203, mir-424, mir-503, mir-505, mir-542, mir-30e, mir-33b, mir-365, mir-758, mir-22, and mir-452 are of interest in the pathogenesis of hemangiosarcoma. CONCLUSIONS: Findings of this study confirm the hypothesis that miRNA expression profiles are different between canine splenic hemangiosarcoma, nodular hyperplasia, and normal spleens. A large portion of the differentially expressed miRNAs have roles in angiogenesis, with an additional group of miRNAs being dysregulated in vascular disease processes. Two other miRNAs have been implicated in cancer pathways such as PTEN and cell cycle checkpoints. The finding of multiple miRNAs with roles in angiogenesis and vascular disease is important, as hemangiosarcoma is a tumor of endothelial cells, which are driven by angiogenic stimuli. This study shows that miRNA dysregulation is a potential player in the pathogenesis of canine splenic hemangiosarcoma.

Effect of histologic processing on dimensions of skin samples obtained from cat cadavers.

OBJECTIVE To determine changes in dimensions of feline skin samples as a result of histologic processing and to identify factors that contributed to changes in dimensions of skin samples after sample collection. SAMPLE Cadavers of 12 clinically normal cats. PROCEDURES Skin samples were obtained bilaterally from 3 locations (neck, thorax, and tibia) of each cadaver; half of the thoracic samples included underlying muscle. Length, width, and depth were measured at 5 time points (before excision, after excision, after application of ink to mark tissue margins, after fixation in neutral-buffered 10% formalin for 36 hours, and after completion of histologic processing and staining with H&E stain). Measurements obtained after sample collection were compared with measurements obtained before excision. RESULTS At the final time point, tissue samples had decreased in length (mean decrease, 32.40%) and width (mean decrease, 34.21%) and increased in depth (mean increase, 54.95%). Tissue from the tibia had the most shrinkage in length and width and that from the neck had the least shrinkage. Inclusion of underlying muscle on thoracic skin samples did not affect the degree of change in dimensions. CONCLUSIONS AND CLINICAL RELEVANCE In this study, each step during processing from excision to formalin fixation and histologic processing induced changes in tissue dimensions, which were manifested principally as shrinkage in length and width and increase in depth. Most of the changes occured during histologic processing. Inclusion of muscle did not affect thoracic skin shrinkage. Shrinkage should be a consideration when interpreting surgical margins in clinical cases. 945).

Effect of vascular seal configuration using the LigaSure on arterial challenge pressure, time for seal creation, and histologic features.

OBJECTIVE: To determine the effectiveness of a vascular sealing technology on canine carotid arteries using various seal configurations to achieve maximal vessel security. STUDY DESIGN: Ex-vivo study. ANIMALS: Dogs (n = 20). METHODS: Carotid arteries (n = 40) were removed from the mid-cervical region of recently euthanatized dogs. Harvested vessels were closed with 2 circumferential ligatures (Group 1) or a vascular sealing device using 1 of 4 seal configurations of 1 or 2 seals combined with 1 or 2 machine activations/seal. The artery was instrumented to measure intraluminal pressure to evaluate the security of each seal during saline infusion. Maximum intraluminal pressure was recorded for each group, and time for application of each sealing protocol was compared using 1-way ANOVA and Tukey's test for multiple comparisons. Histologic features of the sealing protocols were evaluated. RESULTS: Arterial closures for each group were effective in preventing leakage up to 300 mmHg. There was no significant difference in maximum intraluminal pressure between any group. A significant difference (P ≤ .001) was observed for time to seal creation between the groups using 1 and 2 seals. Histologic evaluation showed no differences between the different sealing protocols. CONCLUSION: Vessel sealing using a single seal created with a single activation cycle was adequate for sealing canine carotid arteries. Histologic examination did not demonstrate any disadvantages to multiple seals or multiple cycle activations.