CVMA | Table of Contents and Abstracts

Table of Contents and AbstractsOctober 2019, Vol. 83, No. 4


Vesicular disease in pigs inoculated with a recent Canadian isolate of Senecavirus A

Kate Hole, Thanuja Ambagala, Charles Nfon (page 242)

The objective of this study was to investigate whether a virulent Canadian isolate of Senecavirus A (SVA) causes idiopathic vesicular disease (IVD) in pigs. Senecavirus A, which was first isolated in the United States in 2002 as Seneca Valley Virus, was linked to cases of porcine idiopathic vesicular disease in Canada in 2007 and in the United States in 2010. Since 2014, SVA outbreaks in Brazil, the US, Canada, China, Thailand, and Colombia point to an expanding global distribution and the need to study the pathogenicity of the virus. Unlike the prototype virus, recent US isolates of SVA have been shown to cause vesicular disease in pigs. We report vesicular disease in pigs following experimental inoculation with a 2016 Canadian isolate of SVA. All inoculated pigs developed vesicular lesions regardless of route of inoculation. Virus was detected in blood and oral fluids as well as on oral and fecal swabs. In addition, all pigs seroconverted to SVA by 6 days post-inoculation (DPI). This study confirms that recent Canadian isolates of SVA cause vesicular disease in pigs and highlights the importance of monitoring SVA for increased virulence.

Effectiveness of a commercial porcine reproductive and respiratory syndrome virus (PRRSV) subunit vaccine against heterologous PRRSV-1 and PRRSV-2 challenge in late-term pregnant gilts

Taehwan Oh, Hanjin Kim, Kee Hwan Park, Jiwoon Jeong, Ikjae Kang, Siyeon Yang, Chanhee Chae (page 248)

The objective of the present study was to evaluate the efficacy of a commercial porcine reproductive and respiratory syndrome virus (PRRSV) subunit vaccine against heterologous PRRSV-1 and PRRSV-2 challenge in late-term pregnant gilts. Gilts were vaccinated intramuscularly 56 and 35 days antepartum (on days 58 and 79 of gestation) and challenged intranasally 21 days antepartum (on day 93 of gestation) with PRRSV-1 or PRRSV-2. Regardless of the challenge strain’s genotype, the vaccinated gilts carried their pregnancies to term and farrowed between days 114 and 115 of gestation. All the unvaccinated gilts aborted, between days 105 and 110 of gestation. The vaccinated gilts had a significantly lower level (P < 0.05) of PRRSV viremia and significantly higher levels (P < 0.05) of virus-neutralizing antibodies and interferon-γ-secreting cells compared with the unvaccinated gilts. The mean number of PRRSV-positive cells per area of fetal tissue examined did not differ significantly between the litters from the vaccinated and unvaccinated gilts. The data presented here indicate that vaccination in late-term pregnancy with PRRSV subunit vaccine is efficacious against reproductive failure due to heterologous PRRSV-1 and PRRSV-2 infection.

Effect of nursery feeding program on serum haptoglobin, growth performance, and carcass characteristics of pigs reared on commercial farms

Heather Reinhardt, Anna K. Shoveller, Abdolvahab Farzan, Brian McBride, Lee-Anne Huber, Cornelis F.M. de Lange* (page 255)

A total of 774 pigs were enrolled in 13 cohorts across 7 commercial farms to examine the effect of nursery feeding program on serum haptoglobin, subsequent growth performance, and carcass characteristics of finishing pigs. Pigs were weaned [23.4 ± 0.2 days of age and 5.3 ± 1.5 kg body weight (BW)] and randomly assigned to either a complex (HC: highly digestible sources of proteins, including animal proteins; N = 346) or simple (LC: corn- and soybean meal-based; N = 340) diet for 37.7 ± 1.7 days over 3 phases (1 pen per diet per cohort; pen was the experimental unit; n = 13); sex was balanced between treatments. Thereafter, pigs received common grower-finisher diets. At a targeted BW of 118 kg, pigs (subset: n = 275 and 258 for HC and LC, respectively) were processed to evaluate carcass characteristics. Nursery feeding program did not influence BW, BW gain, or serum haptoglobin at any stage of production. Feed cost was reduced by $2.82 per pig during the nursery period for the LC-fed pigs (P < 0.001). Loin eye depth, back fat depth, carcass weight, percent lean yield, and carcass gross revenue at slaughter were not influenced by nursery feeding program. Feeding LC nursery diets on commercial farms is a feasible way to reduce feed cost without negatively impacting serum haptoglobin, growth performance during or after the nursery period, or carcass value.

Protective efficacy of a Brucella vaccine using a Salmonella-based delivery system expressing Brucella Omp3b, BCSP31, and SOD proteins against brucellosis in Korean black goats

Won-Kyong Kim, Ja-Young Moon, Jeong-Sang Cho, Jin Hur (page 261)

This study aimed to assess the protective efficacy of a novel Brucella vaccine formulation in goats. Twenty black goats were separated into 2 groups. Group A was injected with 3.0 × 109 CFU (colony-forming units)/mL of a Salmonella-based delivery system harboring only vector (pMMP65). Group B was immunized with 3.0 × 109 CFU/mL of the vaccine, a mixture of 3 Brucella vaccine strains (using a Salmonella-based delivery system) expressing each recombinant B. abortus Omp3b, BCSP31, and SOD protein. No Salmonella delivery strain was isolated from all tested lymph nodes and parenchymal organs. Serum immunoglobulin (Ig) G titers and interferon gamma concentrations were significantly higher in group B than those in group A. After intraconjunctival challenge with virulent B. abortus strain 544, 40% of the vaccinated animals in group B were protected against B. abortus infection. The infection index and colonization of B. abortus in tested tissues was significantly lower in group B than group A. We conclude that this Brucella vaccine induces significant antigen-specific immune responses and provides effective protection against B. abortus infection in goats. Further studies are needed to enhance the protection rate of this Brucella vaccine and to discover its practical application in small ruminants.

Stability of epidermal growth factor, fibronectin, and alpha-2-macroglobulin in canine serum under different storage conditions

Cecile Briffod, Christian Bédard, Maria Vanore (page 267)

The objective of this study was to assess whether concentrations of epidermal growth factor (EGF), fibronectin, and alpha(α)-2-macroglobulin in canine serum remain stable under different storage conditions. Serum was obtained from 10 adult dogs and stored for 7 d at room temperature (RT) and at 4°C and for 1, 3, and 6 mo at −20°C. Bacterial cultures of serum were carried out after 7 d at 4°C and at RT. For each dog and time point, EGF, fibronectin, and α-2-macroglobulin were quantified in duplicate by enzyme-linked immunosorbent assay (ELISA). Mean concentrations of each factor at each time point were used for statistical analysis. No bacterial growth was observed in any samples. Compared to baseline (232.24 ± 49.47 pg/mL), EGF concentration was significantly lower after 1 wk of storage at 4°C (135.39 ± 27.12 pg/mL, P = 0.006), but not at RT (315.85 ± 79 pg/mL, P = 0.6) or after 1, 3, or 6 mo of storage at −20°C (220.84 ± 41.07 pg/mL, P = 0.7; 220.98 ± 78.26 pg/mL, P = 0.8; 266.06 ± 20.39 pg/mL, P = 0.4, respectively). Compared to baseline, concentrations of fibronectin after 1 wk of storage at 4°C or at RT and 1, 3, or 6 mo of storage at −20°C were not statistically different. Compared to baseline (186.67 ± 45.20 mg/dL), the concentration of α-2-macroglobulin after 1 wk of storage at 4°C was significantly increased (244.61 ± 58.27 mg/dL, P = 0.002), but not at RT (177.09 ± 26.99 mg/dL, P = 0.2). The differences in concentration after 3 and 6 mo of storage at −20°C were significant compared to baseline (243.32 ± 42.64 mg/dL, P = 0.005 and 56.39 ± 21.78 mg/dL, P < 0.0001, respectively), but not after 1 mo of storage at −20°C (136.79 ± 25.61 mg/dL, P = 0.1). One week of storage at RT has little effect on the stability of EGF, fibronectin, and α-2-macroglobulin in canine serum. Measured factors remain stable for 3 mo of storage at −20°C.

Acute-phase protein profile in horses subjected to different exercise protocols

Pedrita Assunção, Tatiana Barbosa, Letícia Yonezawa, Luciano Barbosa, Marcus Watanabe, Aguemi Kohayagawa, Elizabeth Schmidt (page 272)

High-intensity exercise can be associated with the occurrence of muscle injury, as well as the induction of an acute-phase response (APR). The present study aims to investigate the synthesis and profile of serum proteins in horses before and after participating in 2 different exercise protocols and to relate this profile to the presence or absence of muscular injury caused by exercise. Ten purebred Arabian (n = 5) and Criollo (n = 5) horses were subjected to 2 different tests on a treadmill, one consisting of short-duration and rapid-acceleration training (TRA) that was mostly anerobic and the other of long-duration and slow-acceleration training (TLD) that was predominantly aerobic. Blood samples were obtained before the beginning of exercise (T0) and at 6 post-exercise time points: immediately after (T1) and 30 min (T2), 3 h (T3), 12 h (T4), 24 h (T5), and 48 h (T6) after exercise. Hematocrit was determined by the microhematocrit method. Plasma and serum samples were prepared by centrifugation (1500 × g for 5 min) for plasma concentrations of fibrinogen, total serum proteins (TP), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and creatine-kinase (CK) serum activity. Total protein concentration and CK serum activity were determined in an automated biochemistry analyzer. Fibrinogen was determined by the heat precipitation method in microhematocrit capillary tubes. Estimated concentrations of haptoglobin (Hp) significantly decreased after TRA and estimated concentrations of alpha-1 acid glycoprotein (AGP) significantly increased after both protocols at T2. Albumin increased after the TLD exercise protocol. Changes in hematocrit, haptoglobin, and albumin concentrations in horses subjected to different treadmill exercise protocols are related to a physiological response to hemoconcentration and hemolysis. Increases of AGP in the TLD protocol suggest the release of catecholamines as a response to avoid oxidative damage to tissue.

Pharmacodynamic assessment of ex-vivo canine T-lymphocyte proliferation: Responses to dexamethasone, cyclosporine, mycophenolic acid, and the active metabolite of leflunomide

Megan Grobman, Kaitlin A. Bishop, Hansjorg Rindt, Laura A. Nafe, Carol R. Reinero (page 279)

A lack of understanding of specific immune defects underlying canine immune-mediated diseases hampers optimal therapy. Failure to tailor treatment to an individual’s immune abnormality can result in lack of efficacy, secondary complications, added expense, and drug-potentiated adverse effects. We adopted a small-volume whole-blood flow cytometric assay to determine the effect of immunosuppressant drugs on T-lymphocyte proliferation. Using healthy dogs in this proof-of-principle study, we hypothesized that there would be dose-dependent suppression of T-lymphocyte proliferation in response to dexamethasone, cyclosporine, mycophenolic acid, and the active metabolite of leflunomide (A77 1726). Whole blood was collected from 6 healthy pet dogs and incubated for 4 d with or without the mitogens concanavalin A and lipopolysaccharide and with increasing concentrations of immunosuppressant. Samples were subsequently stained with viability dye and with antibodies against the pan-T-lymphocyte marker CD5 and the cell proliferation marker Ki67. Percentages of proliferating T-lymphocytes were determined by flow cytometry, and the 50% inhibitory concentration (IC50) was calculated. Inhibition of T-lymphocyte proliferation by the panel of immunosuppressants was shown to be dose-dependent, with marked variability among the dogs. The mean IC50 was 394.8 ± 871 (standard deviation) µM for dexamethasone, 18.89 ± 36.2 ng/mL for cyclosporine, 106.3 ± 157.7 nM for mycophenolic acid, and 3.746 ± 6.8 µM for A77 1726. These results support the use of this assay for detecting the efficacy of individual immunosuppressants used to diminish T-lymphocyte proliferation. In future, the assay may be applied to pet dogs with spontaneous immune-mediated disease to help tailor individual treatment.

Comparison of hematologic and biochemical reference values in specific-pathogen-free 1-month-old Yorkshire pigs and Yorkshire–Landrace crossbred pigs

Rui Li, Feng Wang, Yuanyuan Zhang, Changwen Li, Changyou Xia, Hongyan Chen, Xiaoye Lu, Fangping Liu (page 285)

Analysis of hematologic and biochemical values in pigs is an important basis for biomedical research and veterinary clinical diagnosis. Reference values for specific-pathogen-free (SPF) 1-month-old Yorkshire (Y) pigs and Yorkshire–Landrace crossbred (YL) pigs are limited. The present research aimed to describe and compare the reference values for hematologic and biochemical parameters in such pigs. Blood samples were obtained from 90 Y pigs (52 males and 38 females) and 88 YL pigs (55 males and 33 females), all 1 month old and bred in an SPF environment. Among the 16 hematologic and 15 serum biochemical parameters tested, no significant differences between the Y and YL pigs were found except in the concentration of triglyceride (P < 0.05), and heterosis was not observed. Thus, the values determined in this study can be used as basic reference values for 1-month-old Y and YL pigs and will contribute to the use of SPF pigs in biomedical research.

Veterinarians’ attitudes towards use of nutraceuticals

Susan M. Elrod, Erik H. Hofmeister (page 291)

The objective of this study was to assess veterinarians’ understanding of nutraceutical use in humans and companion animals and their motivation and circumstances for recommending nutraceuticals to clients. We administered a cross-sectional survey to veterinarians attending continuing education sessions at the University of Georgia (USA) College of Veterinary Medicine from 2012 to 2015 (N = 126). Information regarding veterinarians’ age, year of graduation, practice focus, and typical approaches to nutraceutical use was compiled from the returned surveys. The results indicated that veterinarians are more familiar with nutraceutical use in animals than in humans and primarily recommend nutraceuticals to their clients for preventative purposes and/or due to client interest. Veterinarians believed that nutraceuticals were most useful for osteoarthritis and therefore use omega-3 fatty acid and glucosamine/chondroitin products more often than other products for both their patients and their own pets. Safety and efficacy were the most important considerations when deciding which nutraceuticals to recommend to clients. The survey results show that veterinarians are familiar with nutraceuticals and open to their use in patients when they perceive these products to be safe and efficacious.

Feasibility of a novel 3-dimensional mathematical algorithmic computation of feline bladder volumes using point-of-care longitudinal and transverse cysto-colic ultrasonographic images

Xiu Ting Yiew, Samantha Clarke, Allan Willms, Shane W. Bateman (page 298)

Conventional geometric formulas for estimating bladder volume assume that bladders have a perfectly uniform spheroid geometry. Bladders are often irregularly shaped, however, especially when under-filled or distorted by a full colon, which results in inaccurate ultrasonographic linear measurements and volume estimation. This pilot study investigates the feasibility, inter-observer reliability (reproducibility), robustness, and agreement of a novel 3-dimensional bladder volume computation method using bladder circumference tracing compared to a published feline linear bladder dimension formula. Paired sets of longitudinal and transverse B-mode bladder ultrasound images (n = 228) were acquired by 2 observers with different point-of-care ultrasonography skills using 10 healthy purpose-bred cats positioned in dorsal recumbency at various time points. Using strict criteria for Lin’s concordance correlation coefficient, inter-observer agreements (n = 223) were found to be substantial (0.95 to 0.99) with statistically significant but clinically non-significant median differences (biases) of 0.96 mL [interquartile range (IQR): 0.16 to 2.46, P < 0.001] and 0.23 mL (IQR: 0.88 to 1.97, P = 0.006) when bladder circumference tracings were made on similar sets of ultrasound images respectively. Inter-observer agreements improved from substantial (0.95 to 0.99) to almost perfect (> 0.99) strength-of-agreement as the quality of ultrasound images improved. The bladder circumference tracing method showed moderate (0.90 to 0.95) strength-of-agreement with the recently published feline linear bladder dimension formula, with significant additive median differences (biases) of −6.76 mL (IQR: −9.06 to −3.88, P < 0.001) and −6.44 mL (IQR: −11.41 to −3.81, P < 0.001) recorded by each observer (n = 111, n = 83), respectively. Data obtained from orthogonal ultrasonographic bladder circumference tracings justify further investigation into use of this method for estimating bladder volume in cats.

Brief Communications

Effect of vaccination of pregnant beef heifers on the concentrations of serum IgG and specific antibodies to bovine herpesvirus 1, bovine viral diarrhea virus 1, and bovine viral diarrhea virus 2 in heifers and calves

Emily J. Reppert, Manuel F. Chamorro, Lacey Robinson, Natalia Cernicchiaro, Joyce Wick, Robert L. Weaber, Deborah M. Haines (page 313)

The objective of this study was to evaluate the effect of late-gestation vaccination of beef heifers with 2 doses of a killed-virus (KV) vaccine containing bovine herpesvirus 1 (BoHV-1), bovine viral diarrhea virus 1 (BVDV-1), and bovine viral diarrhea virus 2 (BVDV-2) on the serum concentrations of antibody against BoHV-1, BVDV-1, and BVDV-2 in heifers and their calves and on the IgG concentration in the calves. Of the 47 pregnant beef heifers selected, 26 received 2 doses of the vaccine at 6.5 to 8 mo of gestation (at pregnancy check), and 21 received 2 doses of saline. The mean log2 serum titers of neutralizing antibody against BoHV-1, BVDV-1, and BVDV-2 before vaccination did not differ significantly between the treatment groups; however, at calving all 3 mean titers were significantly greater (P < 0.05) in the vaccinated heifers than in the control heifers. At 24 h after birth the mean serum IgG levels in the calves did not differ significantly between the 2 groups, at 30.18 and 32.28 g/L, respectively (P < 0.05); however, the mean log2 serum titers of antibody to all 3 viruses were greater in the calves nursing colostrum from the vaccinated heifers than in the calves nursing colostrum from the nonvaccinated heifers and significantly so for BoHV-1 and BVDV-1 (P < 0.001 and P = 0.009, respectively). Thus, late-gestation vaccination of beef heifers could result in a greater and more consistent deposition of specific antibodies in colostrum, reducing the variability of initial titers in calves and increasing the duration of maternal immunity.

Three-dimensional kinematic evaluation of Tightrope CCL in a canine in vitro cranial cruciate deficient stifle model

Mathieu Laugier, Jaëlle Tremblay, Yvan Petit, Alexandre Grignon-Lemieux, Annie Levasseur, Bertrand Lussier (page 317)

The impact of surgical correction of cranial cruciate ligament-deficient stifles (CCDS) on the 3-dimensional (3D) kinematics of the canine stifle has been sparsely evaluated. Tightrope (TR) cranial cruciate ligament (CCL) has been proposed to restore baseline 3D kinematics in CCDS by using isometric points. We hypothesized that TR would restore baseline 3D kinematics of the stifle in our model. Ten pelvic limbs were used with a previously validated apparatus. Three experimental conditions were evaluated: i) intact stifle, ii) cranial cruciate ligament transection (CCLt), and iii) CCLt stabilized with TR; kinematic data was recorded. Tightrope CCL in CCDS did not limit sagittal flexion. Tightrope CCL neutralized internal rotation without restoring baseline curves, but it did not restore abduction, nor did it neutralize or restore cranial translation, but it did restore latero-medial and proximo-distal translations. In our model, TR without pre-conditioning of the FiberTape strands did not restore baseline stifle 3D kinematics and residual cranial translation could result in frequent meniscal tears.