Computed tomographic diagnosis of necroulcerative reticulorumenitis with portal venous gas in a lamb

A 2-month-old, intact male Merino sheep was presented for acute inappetence and pyrexia. Contrast-enhanced abdominal computed tomography identified reticulorumenal intramural gas with suspected ruminal ulceration, arborizing portal venous gas, and mild peritoneal fluid. The lamb was treated medically for presumptive ulcerative reticulorumenitis and non-septic peritonitis. Over 10 days, the lamb initially showed mild improvement before clinical deterioration and was ultimately euthanized. Definitive diagnosis of necrotizing, ulcerative reticulorumenitis was made via necropsy with histopathology. An underlying cause was not determined. Key clinical message: Contrast-enhanced computed tomography was effective in identifying gastric emphysema and portal venous gas associated with reticuloruminal ulceration.

Viruses in unexplained encephalitis cases in American black bears (Ursus americanus)

Viral infections were investigated in American black bears (Ursus americanus) from Nevada and northern California with and without idiopathic encephalitis. Metagenomics analyses of tissue pools revealed novel viruses in the genera Circoviridae, Parvoviridae, Anelloviridae, Polyomaviridae, and Papillomaviridae. The circovirus and parvovirus were of particular interest due to their potential importance as pathogens. We characterized the genomes of these viruses and subsequently screened bears by PCR to determine their prevalence. The circovirus (Ursus americanus circovirus, UaCV) was detected at a high prevalence (10/16, 67%), and the chaphamaparvovirus (Ursus americanus parvovirus, UaPV) was found in a single bear. We showed that UaCV is present in liver, spleen/lymph node, and brain tissue of selected cases by in situ hybridization (ISH) and PCR. Infections were detected in cases of idiopathic encephalitis and in cases without inflammatory brain lesions. Infection status was not clearly correlated with disease, and the significance of these infections remains unclear. Given the known pathogenicity of a closely related mammalian circovirus, and the complex manifestations of circovirus-associated diseases, we suggest that UaCV warrants further study as a possible cause or contributor to disease in American black bears.

Comparison of multilocus sequence types found among North American isolates of Mycoplasma bovis from cattle, bison, and deer, 2007-2017

A prior multilocus sequence typing (MLST) study reported that Mycoplasma bovis isolates from North American bison possess sequence types (STs) different from those found among cattle. The 42 bison isolates evaluated were obtained in 2007 or later, whereas only 19 of 94 (~20%) of the available cattle isolates, with only 1 from North America, were from that same time. We compared STs of additional, contemporary, North American cattle isolates with those from bison, as well as isolates from 2 North American deer, all originating during the same timeframe, to more definitively assess potential strain-related host specificity and expand our understanding of the genetic diversity of M. bovis. From 307 isolates obtained between 2007 and 2017 (209 from cattle, 96 from bison, 2 from deer), we identified 49 STs, with 39 found exclusively in cattle and 5 exclusively in bison. Four STs were shared between bison and cattle isolates; one ST was found in cattle and in a deer. There was no clear association between ST and the health status of the animal of origin. An MLST-based phylogeny including 41 novel STs identified in our study reveals that STs found in bison fall within several divergent lineages that include STs found exclusively in cattle.

Viral testing of 10 cases of Theiler's disease and 37 in-contact horses in the absence of equine biologic product administration: A prospective study (2014-2018)

Background

A novel equine parvovirus (EqPV‐H) was recently discovered in the equine liver with Theiler's disease.

Objectives

To determine the prevalence of EqPV‐H infection in naturally occurring Theiler's disease cases and in‐contact horses in the absence of historical equine biologic product administration.

Animals

Ten cases of Theiler's disease from 6 separate properties were included in the study, based on the criteria of acute onset of clinical signs of liver failure with laboratory or histopathologic findings characteristic of Theiler's disease and no history of receiving an equine biologic product within the preceding 4 months. In addition, 37 in‐contact horses from 4 of the 6 properties were screened for EqPV‐H infection and hepatitis.

Methods

In prospective case series, cases were diagnosed with Theiler's disease by the attending veterinarian and were tested for EqPV‐H by PCR of liver or serum. In‐contact horses were assessed via serum chemistry and PCR at the attending veterinarian's discretion. Hepatitis was defined as serum gamma‐glutamyltransferase activity above reference interval. The association of EqPV‐H with hepatitis was determined by Fisher's exact test.

Results

Nine of 10 (90%) Theiler's disease cases and 54% of tested in‐contact horses were EqPV‐H positive. Hepatitis was significantly associated with EqPV‐H infection (P = .036).

Conclusions and Clinical Importance

Although further study is required to identify EqPV‐H as the causative agent of Theiler's disease, EqPV‐H appears strongly associated with cases of fatal Theiler's disease and subclinical hepatitis in horses in contact with those cases. The prevalence of EqPV‐H infection on affected properties can be high.

Dental pathology in conventionally fed and pasture managed dairy cattle

Healthy teeth are important in the first stages of digestion for dairy cattle, yet little is known about bovine dental disease. This study aimed to investigate dental pathology of dairy cattle in two parts. First dairy cattle cadaver heads (n=11) were examined at the time of culling. Second, the authors performed oral exams in cattle fed a total mixed ration (TMR) (n=200) and pasture-based (n=71) grazing cattle. Cadaver heads were imaged using radiography and computed tomography before gross dissection to study dental anatomy and pathology. The most prevalent dental abnormalities were excessive transverse ridging of the occlusal surface, the presence of diastemas and third molar dental overgrowths (M3DO) in cadaver heads. Average thickness of subocclusal dentine ranged from 3.5 mm to 5.8 mm in cheek teeth but was >10 mm in maxillary teeth with M3DO. Radiographic findings were compared with oral examinations in live cattle. Prevalence of M3DO upon oral examination was 19 per cent and 28 per cent in herds of cattle fed a TMR diet and 0 per cent in a herd of grazing cattle. Dental abnormalities are prevalent in dairy cattle but due to thin subocclusal dentine in the cheek teeth, established equine dental treatment methodology is not appropriate for bovine cheek teeth with the exception of those that have developed M3DO.

Characterization of Cervidpoxvirus Isolates from Oregon, California, and Eastern Canada

The present report describes the analysis of 4 Deerpox virus isolates from California, Oregon, and Ontario, Canada. All 4 isolates were associated with cutaneous crusting lesions. Examination of selected samples by electron microscopy demonstrated that the viruses were morphologically similar to orthopoxviruses. Phylogenetic analysis of the A21 gene, which is found in all poxviruses, indicated that the 4 isolates form a lineage distinct from other members except for those belonging to the genus Cervidpoxvirus of the subfamily Chordopoxvirinae. Members of the Cervidpoxvirus lineage encode a set of genes not found in other poxviruses. These include homologs of genes encoding interleukin 1 receptor antagonists (IL-1Ra) and C-type lectin-like receptors (CTLR). In the current investigation, genes encoding homologs of IL-1Ra and CTLR were amplified from all the isolates and were found to be closely related to orthologs found in the Cervidpoxvirus genus, which further supports the inclusion of these isolates in the Cervidpoxvirus genus.

The influence of diesel exhaust on polycyclic aromatic hydrocarbon-induced DNA damage, gene expression, and tumor initiation in Sencar mice in vivo

The carcinogenic effects of individual polycyclic aromatic hydrocarbons (PAH) are well established. However, their potency within an environmental complex mixture is uncertain. We evaluated the influence of diesel exhaust particulate matter on PAH-induced cytochrome P450 (CYP) activity, PAH-DNA adduct formation, expression of certain candidate genes and the frequency of tumor initiation in the two-stage Sencar mouse model. To this end, we monitored the effects of treatment of mice with diesel exhaust, benzo[a]pyrene (BP), dibenzo[a,l]pyrene (DBP), or a combination of diesel exhaust with either carcinogenic PAH. The applied diesel particulate matter (SRM(1975)) altered the tumor initiating potency of DBP: a statistically significant decrease in overall tumor and carcinoma burden was observed following 25 weeks of promotion with 12-O-tetradecanoylphorbol-13-acetate (TPA), compared with DBP exposure alone. From those mice that were treated at the beginning of the observation period with 2 nmol DBP all survivors developed tumors (9 out of 9 animals, 100%). Among all tumors counted at the end, nine carcinomas were detected and an overall tumor incidence of 2.6 tumors per tumor-bearing animal (TBA) was determined. By contrast, co-treatment of DBP with 50mg SRM(1975) led to a tumor rate of only 66% (19 out of 29 animals), occurrence of only three carcinomas in 29 animals and an overall rate of 2.1 tumors per TBA (P=0.04). In contrast to the results with DBP, the tumor incidence induced by 200 nmol BP was found slightly increased when co-treatment with SRM(1975) occurred (71% vs. 85% after 25 weeks). Despite this difference in tumor incidence, the numbers of carcinomas and tumors per TBA did not differ statistically significant between both treatment groups possibly due to the small size of the BP treatment group. Since bioactivation of DBP, but not BP, predominantly depends on CYP1B1 enzyme activity, SRM(1975) affected PAH-induced carcinogenesis in an antagonistic manner when CYP1B1-mediated bioactivation was required. The explanation most likely lies in the much stronger inhibitory effects of certain PAHs present in diesel exhaust on CYP1B1 compared to CYP1A1. In the present study we also found molecular markers such as highly elevated AKR1C21 and TNFRSF21 gene expression levels in tumor tissue derived from animals co-treated with SRM(1975) plus DBP. Therefore we validate microarray data as a source to uncover transcriptional signatures that may provide insights into molecular pathways affected following exposure to environmental complex mixtures such as diesel exhaust particulates.

Chitosan dressing provides hemostasis in swine femoral arterial injury model

OBJECTIVE

Chitosan dressings have been shown to be effective in improving survival of severe parenchymal injuries in an animal model and in treating prehospital combat casualties. Our goal was to test the efficacy of chitosan acetate dressings in providing durable hemostasis in a high-flow arterial wound model.

METHODS

A proximal arterial injury was created with 2.7-mm vascular punches in both femoral arteries of fourteen anesthetized swine. By using a crossover design, 48-ply gauze (48PG) or a chitosan dressing (HC) was applied with pressure to the injury for 3 minutes and then released. If hemostasis was not maintained for 30 minutes, a second identical attempt was made by using the same dressing type. If hemostasis was still not achieved, the dressing was considered an acute failure and the alternate dressing type was applied. If failure of hemostasis occurred between 30 and 240 minutes after application, the dressing was considered a chronic failure and the artery was ligated.

RESULTS

All 25/25 (100%) of the HC tests and 3/14 (21%) of the 48PG maintained hemostasis for 30 minutes. At 240 minutes, 21/25 (84%) of the HC tests and 1/14 (7%) of the 48PG maintained hemostasis. Statistical analysis by Fischer's exact test shows a significant (p < 0.001) difference in hemostatic efficacy between the 48PG and HC groups in this model, both at 30 minutes and at 240 minutes.

CONCLUSION

Chitosan acetate hemorrhage control dressings provided superior hemostasis to 48 ply gauze in high inguinal femoral arterial injuries. Chitosan-based dressings may provide prehospital treatment options for hemostasis in patients with severe hemorrhagic arterial injuries.

Identification of Mycobacterium avium pathogenicity island important for macrophage and amoeba infection

The ability to infect macrophages is a common characteristic shared among many mycobacterial species. Mycobacterium avium, Mycobacterium tuberculosis, and Mycobacterium kansasii enter macrophages, using the complement receptors CR1, CR3, CR4, and the mannose receptor. To identify M. avium genes and host cell pathways involved in the bacterial uptake by macrophages, we screened a M. avium transposon mutant library for the inability to enter macrophages. Uptake-impaired clones were selected. Sequence of six M. avium clones identified one gene involved in glycopeptidolipid biosynthesis, one gene encoding the conserved membrane protein homologue to the M. avium subsp. paratuberculosis MAP2446c gene and four others belonging to the same region of the chromosome. Analysis of the chromosome region revealed a pathogenicity island inserted between two tRNA sequences with 58% of G+C content versus 69% in the M. avium genome. The region is unique for M. avium and is not present in M. tuberculosis or M. paratuberculosis. Although the mutants did not differ from the WT bacterium regarding the binding to macrophage cell membrane, analysis of macrophage proteins after 1 h infection revealed a deficiency in the mutant to phosphorylate certain proteins on uptake. To understand M. avium interaction with two evolutionarily distinct hosts, the mutants were evaluated for Acanthamoeba castellanii invasion. The defect in the ability of the mutants to invade both cells was highly similar, suggesting that M. avium might have evolved mechanisms that are used to enter amoebas and human macrophages.

Urban dust particulate matter alters PAH-induced carcinogenesis by inhibition of CYP1A1 and CYP1B1

The polycyclic aromatic hydrocarbons (PAHs) benzo[a]pyrene (B[a]P) and dibenzo[a,l]pyrene (DB[a,l]P) are well-studied environmental carcinogens, however, their potency within a complex mixture is uncertain. We investigated the influence of urban dust particulate matter (UDPM) on the bioactivation and tumor initiation of B[a]P and DB[a,l]P in an initiation-promotion tumorigenesis model. SENCAR mice were treated topically with UDPM or in combination with B[a]P or DB[a,l]P, followed by weekly application of the promoter 12-O-tetradecanoylphorbol-13 acetate. UDPM exhibited weak tumor-initiating activity but significantly delayed the onset of B[a]P-induced tumor initiation by two-fold. When cotreated with UDPM, DB[a,l]P-treated animals displayed no significant difference in tumor-initiating activity, compared with DB[a,l]P alone. Tumor initiation correlated with PAH-DNA adducts, as detected by (33)P-postlabeling and reversed-phase high-performance liquid chromatography. Induction of cytochrome P450 (CYP)1A1 and 1B1 proteins was also detected following UDPM treatment or cotreatment with B[a]P or DB[a,l]P, indicating PAH bioactivation. Further genotoxicity analyses by the comet assay revealed that cotreatment of UDPM plus B[a]P or DB[a,l]P resulted in increased DNA strand breaks, compared with PAH treatment alone. The metabolizing activities of CYP1A1 and CYP1B1, as measured by the 7-ethoxyresorufin O-deethylation (EROD) assay, revealed that UDPM noncompetitively inhibited CYP1A1 and CYP1B1 EROD activity in a dose-dependent manner. Overall, these data suggest that components within complex mixtures can alter PAH-induced carcinogenesis by inhibiting CYP bioactivation and influence other genotoxic effects, such as oxidative DNA damage. These data further suggest that in addition to the levels of potent PAH, the effects of other mixture components must be considered when predicting human cancer risk.

The ability to form biofilm influences Mycobacterium avium invasion and translocation of bronchial epithelial cells

Organisms of the Mycobacterium avium complex (MAC) are widely distributed in the environment, form biofilms in water pipes and potable water tanks, and cause chronic lung infections in patients with chronic obstructive pulmonary disease and cystic fibrosis. Pathological studies in patients with pulmonary MAC infection revealed granulomatous inflammation around bronchi and bronchioles. BEAS-2B human bronchial epithelial cell line was used to study MAC invasion. MAC strain A5 entered polarized BEAS-2B cells with an efficiency of 0.1 +/- 0.03% in 2 h and 11.3 +/- 4.0% in 24 h. In contrast, biofilm-deficient transposon mutants 5G4, 6H9 and 9B5 showed impaired invasion. Bacteria exposed to BEAS-2B cells for 24 h had greater ability to invade BEAS-2B cells compared with bacteria incubated in broth. M. avium had no impact on the monolayer transmembrane resistance. Scanning electron microscopy showed that MAC A5 forms aggregates on the surface of BEAS-2B cell monolayers, and transmission electron microscopy evidenced MAC within vacuoles in BEAS-2B cells. Cells infected with the 5G4 mutant, however, showed significantly fewer bacteria and no aggregates on the cell surface. Mutants had impaired ability to cause infection in mice, as well. The ability to form biofilm appeared to be associated with the invasiveness of MAC A5.

Congenital hepatic fibrosis in calves

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Evaluation of lansoprazole (an H+/K+-ATPase inhibitor) and azithromycin (an antibiotic) for control of gastric ulceration in swine during periods of feed deprivation

Helicobacter-like organisms as well as fermentative bacteria have been implicated in gastric ulcer production in swine. Irregular feeding schedules are also considered a major risk factor. A research trial was conducted to determine whether medication with an acid secretion inhibitor (lansoprazole), either alone or in combination with an antibiotic (azithromycin), would protect pigs from gastric ulceration if the animals were subjected to a 48 h period of fasting. In a 2 x 3 factorial design, 48 pigs were fasted, while an equal number were fed ad libitum. Within these 2 study groups, pigs were randomly assigned to 1 of 3 treatments: control, 30 mg lansoprazole s.i.d. for 7 d, or lansoprazole (30 mg s.i.d. for 7 d) and azithromycin (500 mg s.i.d. for 3 d). Overall, fasted pigs were 1.9 times more likely to develop erosive or ulcerative lesions of the pars esophagea (chi2 = 9.89, P < 0.002). Treatment with an acid secretion inhibitor alone or in combination with an antibiotic did not protect pigs from developing gastric lesions. Helicobacter-like organisms were not detected in any of the stomachs. Possibly, the lansoprazole dose of 30 mg given once per day was insufficient to prevent pH levels from becoming low enough to cause damage to epithelial tissue. Alternatively other substances such as bile acids may have caused the ulcerative lesions, even though stomach acid production was suppressed.

Neuronal ceroid-lipofuscinosis in a cat

Neuronal ceroid-lipofuscinosis was diagnosed in a young adult domestic short-haired cat euthanatized because of severe progressive neurologic disease. Clinical signs included blindness, seizures, and decreased mentation. An autofluorescent pigment, identified as ceroid-lipofuscin by electron microscopy and staining properties, was found within neurons of the central and peripheral nervous systems. A diffuse reactive astrocytosis accompanied by multifocal microgliosis was visible in all areas of the brain. Retinal atrophy with intraneuronal lipopigment accumulation was also identified. Contrary to the human neuronal ceroid-lipofuscinoses, pigment deposition appeared to be restricted to neural tissues.

Pulmonary histopathologic findings, acid-base status, and absorption of colostral immunoglobulins in newborn calves

A study was conducted to investigate whether aspiration of amniotic fluid is associated with a deleterious effect on absorption of colostral immunoglobulins or on blood gas and acid-base values of healthy newborn calves. Fourteen calves purchased from commercial sources were transported to a research facility immediately after birth and fed colostrum with known concentrations of immunoglobulins. Blood samples for gas analyses were collected within 5 hours of birth, 24 hours later, and prior to euthanasia. Between 3 and 5 days of age, calves were euthanatized by an overdose of barbiturates. Eleven calves had evidence of bronchoaspiration of amniotic fluid, as determined by presence of meconium, squamous epithelium, or keratin in histologic sections of fixed lung or by cytologic analysis of bronchoalveolar lavage fluid. Blood gas tensions and pH were within reference ranges in 11 of 14 calves. Aspiration of amniotic fluid could not be linked to any specific changes in blood gas tensions, acid-base status, or absorption of colostral immunoglobulins. Presence of keratin and meconium in the lungs often was accompanied by mild exudative alveolitis and focal atelectasis. It was concluded that aspiration of small amounts of amniotic fluid with or without meconium is common in calves and is not associated with hypoxemia, respiratory acidosis, or failure of passive transfer.

Pulmonary inflammation associated with aspirated meconium and epithelial cells in calves

"Meconium aspiration syndrome" is a condition resulting in respiratory distress and the occasional death of newborn human beings. A retrospective study was conducted on 52 calves that were submitted for postmortem examination to the Atlantic Veterinary College, Charlottetown, Prince Edward Island, Canada. These calves died of infectious and noninfectious diseases within the first 2 weeks of life due to a variety of causes. The most common cause of death was infectious enteric disease. Histologic examination of lungs revealed that 42.5% of calves had evidence of meconium, squamous cells, or keratin in the lung. There was considerable variation in the magnitude of histologic changes in lungs containing aspirated material. Typically, affected lungs had only a few inconspicuous pieces of meconium, keratin, and squamous cells within bronchoalveolar spaces. Sporadically, the entire lumen of airways was obliterated by aspirated material. Lungs with aspirated material had a mild but diffuse alveolitis characterized by exudation of a few neutrophils, macrophages, and occasional multinucleated giant cells. Obstruction of small airways and focal atelectasis were also observed. Similar lesions have been reported in human meconium aspiration syndrome. It is concluded that histologic changes similar to those of human meconium aspiration syndrome occur commonly in calves that die within 2 weeks of birth. Further studies involving healthy age-matched calves are required to evaluate the clinicopathologic significance of meconium aspiration in this species.

Neonatal porcine listeriosis

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