Table of Contents and AbstractsAugust 2020, Vol. 61, No. 8
Why the hype — What are microRNAs and why do they provide unique investigative, diagnostic, and therapeutic opportunities in veterinary medicine?
Joshua Antunes, Olivia Lee, Amir Hamed Alizadeh, Jonathan LaMarre, Thomas Gadegaard Koch (page 845)
MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression by inhibiting translation or inducing transcript degradation. MiRNAs act as fine-tuning factors that affect the expression of up to 60% of all mammalian protein coding genes. In contrast to proteins, there is widespread conservation of miRNA sequences across species. This conservation strongly suggests that miRNAs appeared early in evolution and have retained their functional importance. Cross-species conservation provides advantages when compiling candidate markers for health and disease compared to protein-based discoveries. This broad utility is accompanied by the emergence of inexpensive sequencing protocols for the identification of all RNAs in a sample (including miRNAs). With the use of miRNA mimics and antagonists, unique research questions can be answered in biological systems with ‘cause and effect’ methodology. MiRNAs are readily detectable in blood making them attractive candidates as biomarkers for disease. Here, we review their utility as biomarkers and their potential as therapeutic agents or targets to combat disease.
Descriptive network analysis of a Standardbred horse training facility contact network: Implications for disease transmission
Tanya M. Rossi, Rachael M. Milwid, Alison Moore, Terri L. O’Sullivan, Amy L. Greer (page 853)
Infectious respiratory disease is a common cause of morbidity among racehorses. Quantification of contact patterns in training facilities could help inform disease prevention strategies. The study objectives were to: i) describe the contact network among horses, locations, and humans at a Standardbred horse training facility in Ontario; ii) describe the characteristics of highly influential individuals; and iii) investigate how management changes alter the network metrics and discuss the potential implications for disease transmission. Proximity loggers detected contacts among horses, staff, and locations (n = 144). Network metrics and node centrality measures were described for a 2-mode and horse-only contact network. The 2-mode network density was 0.16. and the median node degree was 20 [interquartile range (IQR) = 12 to 27]. Yearlings and floating staff were most influential in the network suggesting biosecurity programs should emphasize reducing contacts in these groups. Removing highly influential staff or co-housing of age groups resulted in changes to network diameter and density.
Resolution of neurologic signs presumed to be associated with hyperammonemia in 2 endurance horses
C. Langdon Fielding, K. Gary Magdesian, Jennifer R. Mayer (page 860)
This case report describes 2 endurance horses with non-hepatic hyperammonemia. The animals were competing in a 160-km endurance competition in extreme heat conditions and were presented for obtundation. One of the horses also had evidence of blindness. The blood ammonia concentration was elevated (196 µmol/L and 249 µmol/L) and both horses improved following treatment with intravenous fluids and supportive care. These are the first documented cases of clinical signs presumed to be associated with hyperammonemia in endurance horses. Despite the severity of the clinical presentation, both horses made a full recovery.
Key clinical message: Non-hepatic hyperammonemia should be considered as a potential cause of blindness and obtundation in competing endurance horses. Horses appear to respond well to treatment with intravenous fluids.
Pulsus alternans in a critically ill dog hospitalized for xylitol toxicity
Nolan V. Chalifoux, Anthony P. Carr (page 865)
A 2-year-old spayed female Great Pyrenees cross dog was presented following the consumption of pure xylitol sweetener. Blood tests revealed hepatocellular leakage and cholestasis, hyperlactatemia, thrombocytopenia, and prolonged prothrombin and activated partial thromboplastin times. Thoracic radiographs on day 2 of hospitalization were consistent with pulmonary hemorrhage. Prior to death, the dog developed pulsus alternans suggestive of myocardial dysfunction secondary to severe systemic inflammation. This is the first report of pulsus alternans in a critically ill dog prior to clinical deterioration and death. This is also the first documentation of pulsus alternans with a high-definition oscillometric device.
Key clinical message: Increased recognition of pulsus alternans and its potential implications in veterinary medicine may contribute to the identification of cardiovascular complications associated with systemic disease.
Use of vessel sealing system for multiple partial lung lobectomies for spontaneous pneumothorax
Alicia Oberhaus, Michael Mcfadden (page 875)
A wolf hybrid dog was presented for dyspnea and tachypnea. Thoracic radiographs revealed a pneumothorax. A median sternotomy was performed, and multiple pulmonary blebs were identified on several lung lobes. Multiple partial lung lobectomies were performed using a vessel sealing system. The dog was discharged 4 days after surgery free of clinical signs related to surgery or pneumothorax. This case represents a novel utilization of a vessel sealing system to remove the apex of the lung when there are numerous pulmonary lesions present.
Key clinical message: A vessel sealing system simplified multiple partial lung lobectomies in an open thoracotomy. The system reduced tissue trauma as well as the amount of normal pulmonary tissue removed while efficiently creating a seal.
Acute toxoplasmosis and pox-viral dermatitis in a juvenile bald eagle (Haliaeetus leucocephalus) in New Brunswick, Canada
Laura Bourque, Spencer J. Greenwood, Megan E.B. Jones (page 880)
Although birds of prey are commonly subclinically infected by Toxoplasma gondii tissue cysts, clinical disease is relatively rare in these species. The present report describes a rare case of fatal toxoplasmosis in a juvenile bald eagle in New Brunswick. Necropsy investigation revealed severe emaciation and poxviral dermatitis which partially obscured the palpebral fissures. Microscopically there was severe lymphoplasmacytic inflammation and necrosis of the lung that was associated with abundant protozoal tachyzoites. Infection with T. gondii was confirmed in the lung via immunohistochemistry and DNA sequencing.
Key clinical message: Wildlife rehabilitation centers should be aware of the potential occurrence of acute clinical toxoplasmosis in stressed malnourished raptors.
Auriculectomy for spontaneous thrombosis of the left auricle in a domestic shorthair cat
Zachary Dvornicky-Raymond, Janis Lapsley, Valentin Janvier, Ileana Miranda, Sean McDonaugh, Galina Hayes (page 885)
A 3-year-old castrated male domestic shorthair cat was presented for evaluation of acute onset tachypnea, dyspnea, and restlessness. Blood analysis revealed markedly elevated creatinine kinase, troponin, and D-dimers, together with azotemia and an inflammatory leukogram. Ultrasonography identified cardiomegaly with pericardial and pleural effusion. Thoracocentesis identified a high protein transudate. Cardiac computed tomographic angiography (CTA) identified an enlarged left auricle containing a non-contrast enhancing mass measuring 1.6 × 1.2 × 1.2 cm subsequently confirmed to be a thrombus. The cat underwent a left cardiac auriculectomy and was discharged on clopidogrel. Post-operative complications, including late-onset hemothorax and dyspnea, were managed to resolution.
Key clinical message: A cardiac auriculectomy was effective in management of thromboembolic disease in a domestic cat.
Comparison of bovine viral diarrhea virus-specific antibody responses of young beef calves vaccinated with either modified live virus or inactivated virus regimens
Nathan Erickson, John Ellis, Cheryl Waldner, Herbert Lardner, Sheryl Gow, John Campbell, Adam Berenik (page 871)
Bovine viral diarrhea virus (BVDV) is an important pathogen causally associated with morbidity and mortality, and production losses in both suckling and weaned beef calves. Vaccination for protection against disease caused by BVDV is challenging because of the inhibitory effect of maternal antibodies; however, it is most convenient for beef producers to vaccinate calves before moving herds to summer pastures. We compared modified live and inactivated vaccines used for priming and boosting beef calves and found that neither type of vaccine results in strong antibody responses in the face of maternal antibodies. These data are generally consistent with previous studies and suggest that alternative protocols using early mucosal delivery followed by parenteral boosting should be examined to improve vaccine efficacy.
Ownership structure and financial status of Canadian dairy operations
Christopher D. Luby, Cheryl L. Waldner, Murray D. Jelinski (page 891)
The ownership structure and financial status of Canadian dairy farms is described using Statistics Canada 2016 Census of Agriculture data. As herd size increased, family corporation became the most common ownership model after accounting for herd location by region. Regardless of location, gross farm receipts, operating expenses and profit margin increased significantly with herd size. Western Canadian dairies occupied significantly larger land bases and had significantly higher profit margins compared to all other regions. New trade agreements could affect the financial stability of Canada’s dairy industry; these data provide a baseline for future comparison.
White line disease in a 19-year-old appendix mare
Leah Ellis (page 895)
A 19-year-old appendix mare was presented with severe, acute right forelimb lameness and a history of significant hoof wall defect. The defect began as progressive toe separation affecting the dorsal hoof wall, which was eventually resected by a farrier. Placement of bar shoes by a farrier to stabilize the hoof was ineffective. Radiographs showed hoof wall separation, palmar rotation, and displacement of the coffin bone, consistent with failure of the laminar structures. Treatment included phenylbutazone, radiographic-guided therapeutic farriery consisting of derotation with a wedge shoe, and restriction to a small, dry paddock.
LETTER TO THE EDITOR
February 2020 ethical question of the month and May 2020 response — Comments
Murray Gillies (page 807)
Christian Klopfenstein (page 807)
Alexandre Jalbert (page 808)
Marian Johnson (page 809)
Leanne Van De Weyer (page 809)
Kirsten Aarbo (page 809)
February 2020 ethical question of the month and May 2020 — Responses to comments
Executive Committee of the Canadian Veterinary Medical Association (page 810)
Carlton Gyles, Editor, The Canadian Veterinary Journal (page 810)
Convenient antimicrobial product versus protection of public health — A comment
John Prescott (page 811)
Carlton Gyles (page 813)
VETERINARY MEDICAL ETHICS
Heather Broughton, Sophie Perreault (page 821)
WHAT CAN’T BE TAUGHT
Valuable mentorship in a public service career
Barry Stemshorn (page 899)
Dalmatian remains true to reputation as fire dog
Leah Parlow, Joel Parlow (page 900)
THE ART OF PRIVATE VETERINARY PRACTICE
Transitional client communication in a changing world
Myrna Milani (page 901)
INDEX OF ADVERTISERS