Presentation, treatment and outcome of long-bone fractures in pet rabbits (Oryctolagus cuniculus)

Retinoic acid induces the osteogenic differentiation of cat adipose tissue-derived stromal cells from distinct anatomical sites

Mesenchymal stromal cells-based regenerative orthopedic therapies have been used in cats as a promising and innovative therapeutic approach to enhance the repair of bone defects. Adipose tissue-derived stromal cells (ADSCs) can be obtained from two main sites-subcutaneous and visceral-with established differences regarding structure, composition, cell content, and functionality. However, in cats, to the best of the authors' knowledge, no studies have been conducted to compare the functional activity of the ADSCs isolated from the two sites, and the impact of these differences on the induced osteogenic potential. Additionally, retinoic acid has been recently regarded as a new osteogenic inducer within cells of distinct species, with undisclosed functionality on cat-derived cell populations. Thus, the present study aimed to evaluate the functional activity of ADSCs isolated from the subcutaneous and visceral adipose sites (SCAT and VAT, respectively) of the cat, as well as the effects of two osteogenic-inducing conditions-the classic dexamethasone, β-glycerophosphate and ascorbic acid-supplemented media (Dex + β + AAM), and Retinoic Acid-supplemented media (RAM). The adipose tissue of subcutaneous and visceral origin was isolated, characterized, and ADSCs were isolated and grown in the presence of the two osteogenic-inducing conditions, and characterized in terms of proliferation, metabolic activity, morphology, and osteogenic activity. Our results demonstrated a distinct biological profile of the two adipose tissue sites regarding cell size, vascularization, and morphology. Further, osteogenic-induced ADSCs from both sites presented an increased expression of alkaline phosphatase activity (ALP) and cytochemical staining, as compared with control. Overall, RAM induced higher levels of ALP activity than Dex + β + AAM, supporting an increased osteogenic activation. Additionally, VAT was the tissue with the best osteogenic potential, showing higher levels of ALP expression, particularly with RAM. In conclusion, different characteristics were found between the two adipose tissue sites-SCAT and VAT, which probably reflect the differences found in the functionality of isolated ADSCs from both tissues. Furthermore, for cat, VAT shows a greater osteogenic-inductive capacity than SCAT, particularly with RAM, which can be of therapeutic relevance for regenerative medicine applications.

Treatment options, complications and long-term outcomes for limb fractures in pet rabbits

BACKGROUND

Limb fractures represent the most common orthopaedic disease in pet rabbits. However, only a few studies have evaluated therapeutic details of limb fractures. There are no data available for long-term outcomes of limb fracture treatment.

METHODS

The medical records of six institutions were reviewed retrospectively to identify cases of traumatic limb bone fractures in pet rabbits between 1999 and 2020. The medical records (n = 387) were analysed for details of fracture prevalence, aetiology, therapy protocols, treatment complications, outcome and long-term effects. In addition to the retrospective data evaluation, 13 rabbits were re-evaluated in person in recent clinical analyses, including orthopaedic examination, radiography and computed-tomographic imaging. Details of long-term effects of fracture treatment were requested over the telephone for a further 232 animals using a standardised questionnaire.

RESULTS

Long bone fractures accounted for the majority of all fractures (296/387; 76.5%). Hindlimb fractures (301/387; 77.7%) were more common than forelimb fractures (86/387; 22.2%), and tibial fractures and combined fractures of the tibia and fibula (119/387; 30.8%) were observed most frequently. Most fracture treatments were based on osteosynthesis procedures (243/328; 74.1%). Treatment complications occurred in 130 out of 328 (39.6%) cases. A high bodyweight (p = 0.047) and an older age (p = 0.01) were found to be significant risk factors for the emergence of therapy complications. Overall, 75.4% of animals (175/232) had a satisfactory long-term outcome. Limb posture anomalies were evaluated in 61 cases (26.3%).

LIMITATIONS

The multi-centre approach led to the inclusion of various institutions, veterinarians, treatment protocols and rabbit populations that might have influenced the results. The medical records were reviewed retrospectively, so there were some data that were lacking or could not be collected in a standardised manner. Furthermore, rabbit owners' evaluation of long-term outcomes might be prone to error, despite the use of a standardised interview questionnaire.

CONCLUSION

Limb fractures are a common orthopaedic issue in pet rabbits. The patient's bodyweight and age are significant risk factors for the emergence of complications during the fracture treatment process. Long-term orthopaedic effects, such as abnormal limb posture and permanent lameness of the affected limb, were observed regularly.

Correlation of Bone Strength in an Animal Model (Rabbit) After Fracture and During the Period of Fixation with a Titanium Micro Plate

The period of bone healing after trauma goes through certain physiological processes. In situations where a bone fracture occurs, our intention is to surgically position in an appropriate morpho-anatomical position. For osteosynthesis we used vipla wire and micro plates with corresponding screws.

The aim of our research was to evaluate the optimal time for the removal of the osteosynthetic material, fracture site biomechanical stability, and measurement of the callus thickness.

For this research ten 4 months old rabbits with right leg femur fracture were used. Osteosynthesis was done with titanium micro plates, corresponding screws and vipla wire. Experimental animals were observed through the post-operative period at the first and seventh postoperative day and there on at 2, 4, 6, 9, 12 weeks. Further additional fixation was needed in one of the rabbits in the second week.

The postoperative period provided us information about the optimal moment for the removal of titanium micro plates. It showed that over a period of six weeks, the bone had almost all normal biomechanical properties. Significantly greater strength and rigidity of the recovered femur were obtained after 12 weeks. Micro plates that were removed after 4, 6 or 9 weeks, did not need furhter fixation and therefore fixation was not applied, compared to those placed during the 12 weeks. X Ray evaluation provided us with follow up results of fracture healing.

The results suggest that it is acceptable to remove titanium micro plates after a period of healing, that is, after the formation of the callus and bridging of the fracture gap and diastasis with newly formed bone.

[Limb fractures in pet rabbits (Oryctolagus cuniculus f. domestica) - A case series of orthopedic long-term effects in fracture patients]

OBJECTIVE

Limb fractures account for a large proportion of all orthopedic diseases in pet rabbits and are a common reason for presentation. The fracture etiologies and characteristics vary considerably in comparison to trauma of the extremities in cats and dogs. For this reason, conservative and surgical treatment options need to be adapted. To our knowledge, long-term effects of limb fracture therapies in pet rabbits have not been described scientifically.

MATERIALS AND METHODS

This article features a case series of 13 pet rabbits with limb fractures. Their medical records were analyzed retrospectively and all patients were presented for a follow-up examination including clinical and orthopedic examination.

RESULTS

Orthopedic anomalies (abducted limb postures) were identified in four patients. Arthrotic ossification was found in twelve of thirteen animals - in six cases to a high extent. Measurement of the fractured bones revealed a shortening in ten of thirteen cases.

CONCLUSION AND CLINICAL RELEVANCE

Orthopedic long-term complications following fracture treatments were commonly detected in the patient population of this study. Permanent issues may result in anomalies of limb posture or postural control which are not noticed by the rabbit owners in every case. Ultimately, the patients should be examined routinely after the conclusion of fracture therapy in order to detect and adequately treat possible orthopedic complications.

Intramuscular Alfaxalone-Butorphanol-Midazolam Compared with Ketamine-Butorphanol- Midazolam in New Zealand White Rabbits

Rabbits are a common companion animal and research subject and frequently require sedation to facilitate procedures. The objective of this study was to compare the effects of intramuscular butorphanol and midazolam combined with either alfaxalone or ketamine in rabbits. In a complete crossover study, healthy New Zealand white rabbits (n = 9; age, 6 mo) randomly received midazolam (1 mg/kg IM) and butorphanol (1 mg/kg IM) combined with either alfaxalone (2 mg/kg IM; ABM) or ketamine (5 mg/kg IM; KBM). Time to first effects, recumbency, and standing (recovery) were recorded. Every 5 min during recumbency, an investigator who was blind to treatment group collected serial physiologic parameters and sedation scores. At 5 min after rabbits became recumbent, manipulations were performed to mimic 2-view radiography and a cephalic intravenous catheter was placed. At 30 min after drug injection, flumazenil (0.05 mg/kg IM) was administered for reversal. Food consumption and fecal output were measured for 3 d after each study day. Time to standing and duration of recumbency differed significantly between groups. The median (range) of the total sedation score for ABM was 10 (8 to 10) and for KBM was 10 (6 to 10). Sham radiographs were successful in all rabbits in both groups. Physiologic parameters were not significantly different between groups over time. At 24 h after drug treatment, KBM-treated rabbits showed reduced food intake and both groups showed reduced fecal output. Total sedation scores decreased significantly over time in KBM rabbits ( P < 0.001) but not in ABM rabbits (P = 1). The duration of recumbency was significantly longer in ABM rabbits than in KBM rabbits. Both protocols produced sufficient sedation for radiograph acquisition without clinically significant adverse effects.

Femoral condylar fractures in four continental giant breed rabbits

Four male neutered continental giant rabbits aged between 10 and 30 months were presented with femoral condylar fractures, which developed without an observed traumatic injury. Stabilisation of the condylar fracture was achieved with screw fixation in all cases, which was supplemented with additional fixation in three cases. Complications consequent to the surgical intervention occurred in two cases: a femoral fracture and loss of fixation. Three rabbits were reported to have recovered normal limb function, and the rabbit that developed a femoral fracture as a consequence of its surgical intervention was treated with amputation.