Comparative Medicine Volume 74: Issue 5

Introduction

A recent editorial discussed the pending merger of the AALAS Comparative Medicine journal into the Journal of the American Association for Laboratory Animal Science (JAALAS), including the rationale supporting the decision and the March 2024 survey results that endorsed this change.³¹ In that editorial, we also briefly noted that the survey results supported full adoption of the ARRIVE (Animal Research: Reporting of In Vivo Experiments) 2.0 guidelines, and we announced that AALAS journals would fully adopt the guidelines starting on January 1, 2025. The purpose of this editorial is to document

The fetal sheep model has been widely used in fetal therapy research. However, there is a significant degree of variability among published normal values. Our study aimed to evaluate the literature available on normal values for hemodynamics, blood gases, and acid-base status in the sheep fetus and to determine the best possible estimation of such physiologic values. We conducted a systematic review with a comprehensive search of several databases. We included 189 articles in the database and over 2,800 sheep fetuses. Analysis revealed a mean umbilical blood flow of 202 mL/kg/min (95% CI: 182 to 223); mean arterial pCO₂ of 49.8 mm Hg (95% CI: 49.2 to 50.3); mean arterial pO₂ of 22.3 mm Hg (95% CI: 21.9 to 22.7); mean arterial pH of 7.35 (95% CI: 7.3487 to 7.3562); and mean arterial oxygen saturation of 59.8 (95% CI; 58 to 61.7). Our findings were punctuated by a high heterogeneity, for which we conducted several subanalyses. The results showed high heterogeneity and small study effect in the literature available and provided our best assessment of relevant variables on normal hemodynamics, blood gases, and acid-base status in the fetus after using strategies to mitigate the risk of bias present in the literature.

It is assumed that hyperextension of the elbow joint beyond 0° in humans is due to local ligament and other soft tissue laxity. The common extant old-world olive baboon (Papio anubis), with a quadrupedal gait, commonly has a mild elbow joint flexion contracture. This study compares anatomic and functional roles of the olecranon-coronoid notch angle of the proximal ulna and the anterior direction of its opening on terminal elbow extension in humans and baboons. Active terminal elbow extension was measured in 211 elbows of skeletally mature humans using the neutral zero method. Passive elbow extension and radiographs were performed on 60 extremities of 30 anesthetized baboons. The mean olecranon-coronoid notch angle for humans and baboons was 22.2 ± 6.0° and 11.3 ± 3.2°, respectively (P < 0.001). Mixed effect regression analysis showed that the magnitude of the angle was a significant predictor of terminal elbow extension (P < 0.001) when accounting for species. Also, the causal mediation analysis showed that 18% of the difference in terminal elbow extension between species could be attributed to the olecranon-coronoid notch angle (P < 0.001). Anatomic dissection of 16 baboon arms showed that sectioning of all the anterior soft tissue structures increased mean terminal elbow extension from −18.2 ± 5.9° to −7.1 ± 6.0° and that further elbow extension was blocked primarily by the intact humeroulnar joint. The size of the notch angle and the positioning of its anterior proximal opening played a significant role in deciding terminal elbow extension in both species.

Significant weight loss in mice (Mus musculus) is a welfare concern and can alter physiology and behavior in ways that may confound research aims. In this study, factorial design was used to investigate the effect of enterally administered capromorelin on changes in mouse body weight overall and with various research-related interventions, such as administration of analgesics, anesthesia, or surgery. BALB/c mice (n = 61 [27 males/34 females] for analysis) were randomized into 8 intervention-treatment groups with 2 treatment allocations: capromorelin (10 mg/kg) or control, and 4 intervention allocations: no intervention; buprenorphine extended-release (XR) alone; buprenorphine XR, meloxicam, and anesthesia; or surgery under anesthesia with buprenorphine XR, meloxicam, and bupivacaine administered. Mice were habituated to handling, weighing, and voluntary consumption of condensed milk, which was used as the control solution and later a vehicle for capromorelin delivery, for 5 d (days 0 to 4). Then, mice received their interventions followed by 3 days of daily treatment or control administration (days 7 to 9). Body weights were measured daily (days 8 to 11 and day 14) to compare with baseline weights (days 0 to 4 and day 7) and evaluate for treatment and intervention effects on body weight. The interventions resulted in a decrease in group body weights 3 and 4 d after the interventions were conducted. Overall, body weights increased more in mice given capromorelin compared with control, and mice treated with capromorelin returned to, or exceeded, baseline weights faster. The weight loss was mitigated by capromorelin administration in all interventions except for the buprenorphine XR-only group. It is recommended to clinically consider enterally administered capromorelin to mitigate research-induced weight loss in mice.

Optimization of Ketamine/Xylazine Anesthesia in Geriatric Mice

Sidney BeecyDVM,

Desiree MeuseBS, LATG,

Nicole KizielewiczDVM,

Corinna BealeDVM, DACLAM, and

Denise MolkVMD, DACLAM

Comparison of Dexmedetomidine/Morphine and Xylazine/Morphine as Premedication in Isoflurane-Anesthetized Sheep

Ekkapol AkaraphutipornDVM, PhD,

Patmanachatr BunnagDVM, PhD,

Vudhiporn LimprasutrDVM, PhD,

Kasem RattanapinyopitukDVM, MSc, PhD, DTBVP,

Sumit DurongphongtornDVM, DVSc, DTBVS,

Luisito S PabloDVM, DACVAA,

Patrick SharpDVM, MRCVS, MANZCVS, DACLAM,

Cholawat PacharinsakDVM, PhD, DACVAA, and

Chalika WangdeeDVM, MSc, PhD, DTBVS, De Facto AiCVS

The ARRIVE 2.0 Guidelines: Importance and Full Adoption by AALAS Journals

Introduction

A Systematic Review and Meta-Analysis of Physiologic Variables in Sheep Fetuses

Comparison of Terminal Elbow Extension between Humans and Baboons (Papio anubis)

Investigating the Effect of Enterally Administered Capromorelin on Body Weight in Mice (Mus musculus)

Effectiveness, Safety, and Pharmacokinetics of Meloxicam Formulations in African-clawed Frogs, Xenopus laevis

Prevalence and Pathologic Characterization of Mouse Kidney Parvovirus in Sentinel CD1 Mice

Characterization of Effect of Enterovirus D68 in 129/Sv Mice Deficient in IFN-α/β and/or IFN-γ Receptors

Pathophysiological and Pedigree Analysis of Left Ventricular Noncompaction in Japanese Macaques (Macaca fuscata)

AALAS Members

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Laboratory Animal Science Professional: July/August 2025

Optimization of Ketamine/Xylazine Anesthesia in Geriatric Mice

Comparison of Dexmedetomidine/Morphine and Xylazine/Morphine as Premedication in Isoflurane-Anesthetized Sheep

Comparison of Intrarenal and Intravenous Injections of Sodium Pentobarbital for Euthanasia in New Zealand White Rabbits (Oryctolagus cuniculus)

Repeated Administration of Pharmaceutical-Grade Medium-Chain Triglycerides, a Common Pharmacologic Excipient, Confers Dose-Dependent Toxicity by the Intraperitoneal but Not Oral Route in Mice