Role of subchondral bone properties and changes in development of load-induced osteoarthritis in mice.

OBJECTIVE: Animal models recapitulating post-traumatic osteoarthritis (OA) suggest that subchondral bone (SCB) properties and remodeling may play major roles in disease initiation and progression. Thus, we investigated the role of SCB properties and its effects on load-induced OA progression by applying a tibial loading model on two distinct mouse strains treated with alendronate (ALN). DESIGN: Cyclic compression was applied to the left tibia of 26-week-old male C57Bl/6 (B6, low bone mass) and FVB (high bone mass) mice. Mice were treated with ALN (26 µg/kg/day) or vehicle (VEH) for loading durations of 1, 2, or 6 weeks. Changes in articular cartilage and subchondral and epiphyseal cancellous bone were analyzed using histology and microcomputed tomography. RESULTS: FVB mice exhibited thicker cartilage, a thicker SCB plate, and higher epiphyseal cancellous bone mass and tissue mineral density than B6 mice. Loading induced cartilage pathology, osteophyte formation, and SCB changes; however, lower initial SCB mass and stiffness in B6 mice did not attenuate load-induced OA severity compared to FVB mice. By contrast, FVB mice exhibited less cartilage damage, and slower-growing and less mature osteophytes. In B6 mice, inhibiting bone remodeling via ALN treatment exacerbated cartilage pathology after 6 weeks of loading, while in FVB mice, inhibiting bone remodeling protected limbs from load-induced cartilage loss. CONCLUSIONS: Intrinsically lower SCB properties were not associated with attenuated load-induced cartilage loss. However, inhibiting bone remodeling produced differential patterns of OA pathology in animals with low compared to high SCB properties, indicating that these factors do influence load-induced OA progression.

Evaluation of antimicrobial usage in companion animals at a Veterinary Teaching Hospital in Nigeria.

This study investigated various qualitative and quantitative indices of antimicrobial use (AMU) in companion animals (CAs) at a Veterinary Teaching Hospital (VTH-A) and its annex (VTH- B) from 2019 to 2021. For 694 documented animals, antimicrobial administrations (AADs) were 5, 278 times, of which 98.8% (5217) and 1.2% (61) were in dogs and cats respectively. At the VTH- A, oxytetracycline (1185 times, 22.5%) was mostly administered in dogs and metronidazole (26 times, 0.5%) in cats. Similarly, at VTH- B, oxytetracycline was administered 895 times (17.0%) in dogs while amoxicillin was given 7 times (0.1%) in cats. The prescription diversity (PD) was estimated at 0.73 and 0.82 in VTH-A and VTH-B respectively. The quantity of antimicrobials (AMs) used was 10.1 kg (A, 6.2 kg and B, 3.9 kg). Oxytetracycline administrations and quantity of metronidazole (P < 0.0001) were higher than other Active Ingredients (AIs). Furthermore, 16.5% of AIs were classified as Critically Important Antibiotics (CIA) with the highest priority, while enrofloxacin, ciprofloxacin, and azithromycin fell under the World Health Organisation (WHO) Watch group. The In-Depth Interview (IDI) indicated that the high frequency of oxytetracycline administrations was linked with being the first choice for blood parasite treatment by the clinicians at the hospital. The quantity of metronidazole used was perceived to be higher due to the clinicians' preference for the treatment of acute gastroenteritis, its wider dose range, and the frequency of administration (bi-daily). The study provides baseline data on AMU indices in CAs, for the development of antimicrobial stewardship (AMS) and communication training, and policy modifications to enhance antimicrobial therapy optimization in tertiary veterinary hospital care in Nigeria.