Table of Contents and Abstracts

The domestic dog has been given considerable attention as a system for investigating the genetics of human diseases. Population diversity and breed structure are unique features that make dogs particularly amenable to genetic studies. Dogs show distinguished features of breed-specific homogeneity, which is associated with striking interbreed heterogeneity. This review discusses the significance of studying the genetic maps, genome-wide association studies (GWAS), and usefulness of this species as an animal model. Most canine genetic disorders are similar to those of humans, including inherited, psychiatric, and genetic disorders. In addition to revealing new candidate genes, canine models allow access to experimental resources, such as cells, tissues, and even live animals, for research and intervention purposes.

Endotoxin-induced diseases cause significant mortality and morbidity in the horse, leading to enormous economic damage to the equine industry. Neutrophils play a critical role in initiating the immune response in the lung. Pattern recognition receptors (PRRs) are programmed to recognize microbial structures unique to pathogens and mount an immune response. Pentraxin 3 (PTX3) is a PRR that is produced at sites of inflammation by many cell types upon stimulation by pro-inflammatory cytokines and agonists, such as endotoxins [also known as lipopolysaccharides (LPS)]. Pentraxin 3 recognizes and binds to many pathogens, activates the complement cascade, and has a role in the clearance of apoptotic and necrotic cells. Recently, PTX3 has been reported to be localized in the specific granules in human and mouse neutrophils, but no reports exist on the in-situ localization of PTX3 in neutrophils and the lungs of horses. Therefore, the objective of this study was to localize the PTX3 protein in normal and LPS-exposed neutrophils and in normal equine lungs. Immunohistochemical data showed PTX3 staining in the bronchial epithelial cells and the vascular endothelium of normal lungs. Immunogold electron microscopy localized PTX3 in the nuclei, cytoplasm, and vesicular organelles of alveolar macrophages, endothelial cells, and pulmonary intravascular macrophages. Immunohistochemical staining for PTX3 in isolated horse neutrophils showed an altered staining pattern in neutrophils stimulated with LPS. These data suggest that neutrophils may be a mobile form of PTX3 that is readily shuttled to the site of inflammation, where it can be released to fine tune a host defense response.

The objective of this study was to determine the relationship of bull location (shade versus no shade), scrotal subcutaneous and ambient temperatures, and sperm quality. Six Angus bulls (4 to 5 y) were randomly allocated into 2 groups of 3 bulls each, housed in 2 outdoor pens, with 1 containing a shed (~3.5 × 6 m and 2.5 m high, 1 open side) to provide shade. Semen was collected by electroejaculation once weekly for 9 wk. The percentage of time a bull voluntarily accessed shade for ≥ 15 min (observed with a game camera) increased with the ambient temperature and ranged from 7.6% to 86.7% for ambient temperatures of < 25°C and > 33°C, respectively. During the 10 hottest days, scrotal subcutaneous temperature (measured hourly with an implanted data logger) in the bulls without access to shade (control group) was directly associated with ambient temperature. Conversely, bulls with access to shade had lower (P = 0.001) scrotal subcutaneous temperatures during high ambient temperatures, particularly when they accessed shade. During the 4 hottest days, these bulls voluntarily accessed shade most of the time from 12:00 noon to 5:00 p.m. (peak ambient temperatures). For total sperm morphological abnormalities and acrosome integrity, there were group effects (P = 0.001 for each), plus a time effect for acrosome integrity (P = 0.009). For total and progressive forward sperm motility, there were group effects (P = 0.001 and 0.023, respectively). For sperm motility kinetics, which were measured with computer-assisted sperm analysis (CASA), [average path velocity (VAP), curvilinear velocity (VCL), straight line velocity (VSL), straightness of track (STR), and linearity of track (LIN)], there were also group effects (P = 0.005, 0.011, 0.010, 0.020, and 0.046, respectively). In summary, during hot weather, bulls voluntarily accessed shade, which significantly lowered scrotal subcutaneous temperatures and improved sperm quality.

E-cadherin is an adhesion molecule expressed on epithelial surfaces. Loss of its expression is described in cancerous tissues. Here, we examined the expression of E-cadherin in canine cutaneous squamous cell carcinoma (SCC) and determined its association with tumor grade (TG), proliferation index (PI), apoptosis index (AI), and intra-tumoral microvascular density (iMVD) in archived samples. Thirty-six cutaneous SCC samples (archived from 2014 to 2019) were graded and E-cadherin level, Ki67 (PI), von Willebrand factor (iMVD), and apoptosis (AI) were determined immunohistochemically. Tumor grades were assigned as Grade 1 (n = 18), Grade 2 (n = 16), and Grade 3 (n = 2). Of the 36 tumors, 21 were digital and 15 were from other locations, including the tail, neck, ear, and elbow. The median E-cadherin score decreased statistically (P = 0.03) with an increase in TG. There was a negative association between median E-cadherin score and TG (r = -0.445, P = 0.013), AI (r = -0.342, P = 0.08), and PI (r = -0.459, P = 0.016). The median E-cadherin score was significantly higher in digital SCC compared to SCC from other locations (P = 0.035). In conclusion, a negative association was observed between TG, PI, AI, and E-cadherin.

In obese dogs, oxidative stress is associated with inflammatory processes and systemic endocrine imbalances. Monitoring oxidative status is an early and valuable means of obesity control as it is a marker of weight loss, which leads to a reduction in oxidative status or injury potential. The objective of this study was to investgate the changes in the concentrations of thiobarbituric acid reactive substances (TBARS) and symmetric dimethylarginine (SDMA) in obese female dogs subjected to an 8-week weight-loss program. We included obese female dogs without comorbidities and with body condition scores (BCS) of 8 and 9 out of 9. In addition to TBARS and SDMA assessments, laboratory tests of blood and urine (blood count; levels of serum biochemistry; albumin, alanine aminotransferase, alkaline phosphatase, creatinine, urea, triglycerides, cholesterol, and glucose; urinalysis; and albuminuria), systolic blood pressure, and hormone concentrations (insulin, cortisol, and free thyroxine) were carried out before and after the weight-loss program. All the obese dogs presented high TBARS levels. After the program, the dogs showed significant reductions in TBARS (P = 0.005) and SDMA (P = 0.0013). In conclusion, obese female dogs were prone to lipid peroxidation and the TBARS and SDMA levels decreased after the 8-week weight-loss program.

Commercial products containing immunoglobulin G (IgG) sourced from colostrum, milk, and/or serum may be used to supplement or replace maternal colostrum in newborn dairy calves. To determine if antibody specificities in bovine milk and serum IgG differ from colostrum IgG, we sampled serum, colostrum (1 to 2 hours post-partum), and milk (day 5 post-partum) from 24 dairy heifers or cows. Specific antibodies [IgG class (H&L)] to 8 common pathogens were measured using enzyme-linked immunosorbent assays (ELISAs). Immunoglobin G1 and IgG2 subclass-specific ELISAs were performed for 3 of these pathogens. Colostrum-derived IgG contained more specific antibodies to rotavirus [IgG (H&L) and IgG1] and to IgG (H&L) of bovine respiratory syncytial virus (BRSV), bovine parainfluenza-3 virus (BPI₃V), Staphylococcus aureus, Escherichia coli F5 (K99), and bovine coronavirus than milk IgG. Colostral IgG contained more antibodies to BRSV (IgG1), rotavirus (IgG1), and IgG (H&L) specific for BRSV, bovine herpesvirus-1 (BHV-1), BPI₃V, E. coli F5 (K99), and Streptococcus uberis than serum IgG. Compared to serum, milk contained more IgG (H&L) antibody to BRSV, BHV-1, and BPI₃V, IgG1-specific BRSV, and rotavirus. These data indicate that IgG derived from colostrum delivers more specific antibodies to these endemic pathogens of calves compared to IgG sourced from milk or serum. In addition, the IgG1 subclass predominates in milk and colostrum, and both deliver a similar spectrum of antibodies.

The objective of this study was to compare the virulence of 4 porcine circovirus type 2 (PCV-2) genotypes (2a, 2b, 2d, and 2e) in pigs singly infected with 1 of these 4 PCV-2 genotypes and pigs dually infected with a combination of 1 of the 4 PCV-2 genotypes and porcine reproductive and respiratory syndrome virus (PRRSV). Virulence was determined based on levels of PCV-2 loads in the blood and lymph nodes and the severity of lymphoid lesion. Within the singly infected groups, PCV-2a, PCV-2b, and PCV-2d resulted in a similar virulence to each other and all were more virulent than the PCV-2e groups. Within the dually infected groups, the combination of PCV-2d and PRRSV was more virulent than the other 3 PCV-2 genotypes (2a, 2b, and 2e), each in combination with PRRSV. Both PCV-2a+PRRSV and PCV-2b+PRRSV were more virulent than PCV-2e+PRRSV in dually infected pigs. This increased virulence of PCV-2d compared to the other 3 PCV-2 genotypes (2a, 2b, and 2e) may be attributed to an extra amino acid (lysine residue) found within open reading frame 2 (ORF2) of PCV-2d. In contrast, extra amino acids in ORF2 may decrease the virulence of PCV-2e when compared to the other 3 PCV-2 genotypes (2a, 2b, and 2d). The results of this study demonstrated that PCV-2d was the most virulent PCV-2 genotype in pigs co-infected with PRRSV. The results also suggest that genetic differences in the ORF2 of PCV-2 may affect the virulence of PCV-2 genotypes.

Enterococci are environmental pathogens that can cause bovine mastitis, which is treated with macrolides, one of which is erythromycin (ERY). The aim of this study was to compare the characteristics of high-level erythromycin-resistant (HLER) Enterococcus faecalis (E. faecalis) isolates from bulk tank milk of 4 dairy companies, identified as A to D, in order to assess the threat to public health. Although isolates from company D showed the highest prevalence of E. faecalis, the prevalence of HLER E. faecalis in isolates from company A showed a significant difference. A total of 149 of the 301 HLER E. faecalis isolates showed the highest rate of resistance to tetracycline. In the distribution of antimicrobial resistance genes, 147 isolates carried the ermB gene alone and 2 isolates carried both ermA and ermB genes. Also, 72 and 60 isolates carried both tetM and tetL genes and the tetM gene alone, respectively, and 38 isolates carried the optrA gene. The prevalence of both aac(6′)Ie-aph(2″)-la and ant(6′)-Ia genes was the highest and 104 isolates harbored the Int-Tn gene carrying the Tn916/1545-like transposon. Although the distribution of the ermB gene showed no significant difference among dairy companies, the prevalence of other resistance genes and transposons showed significant differences among dairy companies. Virulence genes were highly conserved in the HLER E. faecalis isolates. Our results indicated that there were significant differences in phenotypic and genotypic characteristics of HLER E. faecalis isolates in milk from 4 different dairy companies. A structured management protocol by companies and constant monitoring are therefore necessary to minimize public health hazards.

Biofilm (BF) formation is a considerable obstacle to the effective control of Listeria monocytogenes (LM). In this study, we used transcriptomics to analyze LM BF and planktonic bacteria at different stages of BF formation and growth to compare differential gene expression between the 2. We identified 1588, 1517, and 1462 differentially expressed genes (DEGs) when early formation BF and planktonic bacteria were compared at 12, 24, and 48 h, respectively. Among these, 1123 DEGs were shared across the 3 data pool. Gene Ontology functional enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses demonstrated significant changes associated with the phosphotransferase system, the microbial metabolism in diverse environments, the flagella assembly, the bacterial chemotaxis, the bacterial secretion, the quorum sensing, and the 2-component system. The top 5 upregulated DEGs were lmo0024, lmo0374, lmo0544, hly, and lmo2434. The top 5 downregulated DEGs were lmo2192, lmo1211, cheY, lmo0689, and secY. After real-time quantitative polymerase chain reaction, the expression of these 10 DEGs were consistent with the results of the transcriptomic sequence. This research lays the foundation for further studies on mechanisms regulating BF formation and will help to identify BF inhibitors to reduce the risk of LM infection.

The objective of this retrospective case series was to report overall peri-operative complications, short- to mid-term outcome, and owner satisfaction of closing tibial wedge osteotomy (CTWO) using locking compression plates, in dogs weighing ≤ 20 kg, for the treatment of cranial cruciate ligament disease.

Medical records from 2015 to 2020 were reviewed for surgical technique, intraoperative findings, and complications. Pre- and postoperative radiographs were evaluated for healing, complications, and tibial plateau angles (TPAs). A follow-up telephone questionnaire was used to evaluate patient outcome and owner satisfaction.

Eighty-one client-owned dogs (12.0 kg ± 3.0 kg; 95% CI: 8.4 to 15.5) (N = 89 stifles) were included in the study. Mean tibial plateau angles at preoperative, postoperative, and 8-week follow-up were 29.7° ± 4.1° (95% CI: 25.5 to 33.8), 6.7° ± 2.6° (95% CI: 4.2 to 9.2), and 7.8° ± 2.4° (95% CI: 4.9 to 10.6), respectively. Tibial plateau angles had significantly increased at the 8-week follow-up assessment by 1.04° ± 1.8°; 95% CI: -0.8 to -2.8) compared to immediately postoperative. The postoperative complication rate was 4.49% (4 cases). Overall satisfaction was excellent with good return to limb function.

Closing tibial wedge osteotomy can be performed in dogs ≤ 20 kg, using locking compression plates, achieving excellent overall owner satisfaction and return to function.

The objective of this study was to evaluate unidimensional (mm), bidimensional (mm²), or tridimensional (mL) computed tomography (CT) tumor measurements for ability to discriminate changes in lesion size and predict survival in dogs with nonresectable hepatic carcinoma treated with drug-eluting bead transarterial-chemoembolization (DEB-TACE) and to compare CT response via Response Evaluation Criteria in Solid Tumors 1.1 (mm), World Health Organization (mm²), ellipsoid and spherical volume (mL), and percent necrosis, for their ability to differentiate treatment responders. This was a prospective, single-arm clinical trial. DEB-TACE was performed to varying levels of blood flow stasis in 16 client-owned dogs with nonresectable hepatic carcinoma. Computed tomography imaging responses were assessed and compared to median survival time. Results revealed that initial, follow-up, or changes in unidimensional, bidimensional, or tridimensional tumor measurements were not associated with survival. Larger bidimensional and tridimensional tumor measurements/body weight on initial and follow-up CT were significantly associated with a shorter median survival time [bidimensional (P = 0.04, 0.016) and tridimensional (P = 0.025, 0.015), respectively]. A higher percent necrosis on initial CT was significantly associated with a shorter median survival time (P = 0.038). Ellipsoid volumetric criteria detected treatment response most frequently; however, response classification was not associated with median survival time. Computed tomography bidimensional and tridimensional tumor measurements/body weight before and after DEB-TACE may help to predict median survival time for dogs undergoing DEB-TACE for hepatic carcinoma.