Video‐Assisted Thoracoscopic Resection of Noninvasive Thymomas Using One‐Lung Ventilation in Two Dogs

Objective— To report the technique and outcome of video‐assisted thoracoscopic surgery (VATS) for resection of cranial mediastinal thymoma in 2 dogs. Study Design— Case report. Animals— Eleven‐year‐old Labrador Retrievers (n=2). Methods— Two dogs had VATS resection of thymoma. Preoperative computed tomography (CT) scans revealed well‐circumscribed cranial mediastinal masses with dimensions of 4.5 cm × 4.2 cm × 3.7 cm and 2.1 cm × 2.1 cm × 4.1 cm (at the time of resection) without CT evidence of vascular invasion. One‐lung ventilation (OLV) was achieved using a bronchoscopically placed double‐lumen endobronchial tube. A 3‐portal technique was used for VATS access to the thorax. Thymomas were dissected from the tissues of the cranial mediastinum with the aid of a harmonic scalpel and retrieved in specimen retrieval bags. Results— Two cranial mediastinal thymomas were resected successfully, with their capsules intact, using a VATS technique. One dog developed aspiration pneumonia postoperatively which resolved with treatment and remains healthy 18 months postoperatively with no radiographic evidence of tumor recurrence. The second dog was diagnosed with myasthenia gravis, megaesophagus, and aspiration pneumonia preoperatively and despite recovering well from the procedure had a second episode of aspiration pneumonia 5 days postoperatively and was euthanatized. Conclusions— VATS resection of modestly sized noninvasive thymoma is possible in dogs. Careful case selection and preoperative imaging are the keys. Clinical Relevance— Thoracoscopic resection of modestly sized mediastinal masses forms part of an increasingly expansive set of indications for minimally invasive surgery in select veterinary patients.     

Antioxidant supplementation,effect on post‐thaw spermatozoan function in three sturgeon species

High levels of reactive oxygen species (ROS), which may be associated with reduced sperm quality, can be detected during cryopreservation of sperm of some species. Our objective was to investigate whether the addition of antioxidants to cryopreservation extenders influenced post‐thaw sperm characteristics and fertility in Acipenser dabryanus, Acipenser sinensis and Acipenser baerii. Prior to freezing, sperm samples were diluted with a base extender as control or in extender supplemented with catalase (CAT), glutathione (GSH), cysteine (NAC), ascorbic acid (VC) or their paired combinations. Protective concentrations of CAT, GSH and VC in the three species were 25 U/ml, 0.25‐0.5 mg/ml and 0.5 mg/ml, respectively. Cysteine showed no protective effect against ROS. The addition of CAT, GSH and VC positively affected either acrosome or membrane integrity of post‐thawed sperm in the three species, as well as spermatozoan motility in A. sinensis. The combination of antioxidants did not show a positive synergistic effect. This study suggested that the use of antioxidants in the cryopreservation of sturgeon sperm has potential to decrease intracellular ROS, and consequently preserve acrosome and membrane integrity, as well as spermatozoan motility.     

Clinical presentation and disease prevalence of captive central bearded dragons (Pogona vitticeps) at veterinary clinics in Australia

Central bearded dragons (Pogona vitticeps) are one of the most popular reptile pets in Australia and around the world. Diseases, including metabolic bone disease, periodontal disease, and gastrointestinal endoparasites commonly affect captive animals. To determine the common reasons these lizards were presented to the veterinarian and to establish the prevalence of disease seen in captive P. vitticeps in Australia, this retrospective study evaluated the clinical records of three exotic pet veterinary hospitals. Records from 724 P. vitticeps were analysed, with 70 reasons for presentation and 88 diseases identified across 1000 visits to the veterinarian. Lethargy was the most reported reason for presentation (n = 181). The gastrointestinal tract (18.25%) and skin (18.25%) were the equally most commonly affected organ systems, followed by the musculoskeletal system (15.17%). Endoparasites were the most common single disease process (n = 103), followed by metabolic bone disease (n = 65), skin wounds (n = 59) and periodontal disease (n = 48). Of the patients that presented for routine preventive health examinations (n = 159), 45.30% received some form of intervention to treat or prevent disease. Many of the conditions that were identified by the veterinarians in this study are traditionally correlated with suboptimal husbandry and may be easily prevented. This study identified the common reasons for presentation to the veterinarian and the prevalence of disease in captive P. vitticeps in Australia, providing the first extensive retrospective analysis of objective reference literature for central bearded dragon owners and aspiring reptile veterinarians.     

Biomechanics of Cranial Cruciate Ligament Reconstruction in the Dog II. Mechanical Properties

A biomechanical analysis of the results of an over-the-top procedure for replacement of the cranial cruciate ligament (CCL) in the dog is presented. Using 15 adult mongrel dogs, the CCL in one stifle joint was reconstructed using fascia lata and the lateral one-third of the patellar ligament. The opposite CCL served as the control. Animals were sacrificed at 0, 4, 12 and 26 weeks postoperation and axial failure tests were performed. Stiffness, maximum load, and elastic modulus of the replacement increased over time, while elongation to maximum load continually decreased as compared to controls. Other parameters showed less consistent trends.
The results are encouraging given the reduction in joint laxity and the increases in tissue stiffness and strength. However, the ligament substitute was still unable to replicate the mechanical properties of the normal cruciate ligament. Longer studies therefore are required to determine if this replacement is capable of completely restoring joint stability and normal function.     

A century of transformation: fire regime transitions from 1919 to 2019 in southeastern British Columbia,Canada

Context

In fire-excluded forests across western North America, recent intense wildfire seasons starkly contrast with fire regimes of the past. The last 100 years mark a transition between pre-colonial and modern era fire regimes, providing crucial context for understanding future wildfire behavior.

Objectives

Using the greatest time depth of digitized fire events in Canada, we identify distinct phases of wildfire regimes from 1919 to 2019 by evaluating changes in mapped fire perimeters (>?20-ha) across the East Kootenay region (including the southern Rocky Mountain Trench), British Columbia.

Methods

We detect transitions in annual number of fires, burned area, and fire size; explore the role of lightning- and human-caused fires in driving these transitions; and quantify departures from historical fire frequency at the regional level.

Results

Relative to historical fire frequency, fire exclusion has created a significant fire deficit in active fire regimes, with a minimum of 1–10 fires missed across 46.4-percent of the landscape. Fire was active from 1919 to 1939 with frequent and large fire events, but the regime was already altered by a century of colonization. Fire activity decreased in 1940, coinciding with effective fire suppression influenced by a mild climatic period. In 2003, the combined effects of fire exclusion and accelerated climate change fueled a shift in fire regimes of various forest types, with increases in area burned and mean fire size driven by lightning.

Conclusions

The extent of fire regime disruption warrants significant management and policy attention to alter the current trajectory and facilitate better co-existence with wildfire throughout this century.

Graphical abstract