In the long history of mankind, animals have played significant roles.We owe much of our intellectual sophistication and societal status to animal husbandry. 1 Farming and agriculture have allowed humans to control their environment and an improved nutrition. The first rural settlements marked the birth of the ancient civilizations, 2 but also triggered the first zoonotic outbreaks and the beginning of public health concerns. 3 The earliest records of animal use coincide with the appearance of Hippocrates' concepts and the birth of Western medicine. 2 Jumping ahead 2400 years, in the year 2018 more than 20 000 animal subjects-exceeding 200 species-were part of translational studies worldwide, 4 in pre-clinical trials. 2 Animal modelling can provide reliable data to elucidate human diseases. 5 Despite benefiting our quality of life, animal research remains controversial. 3 There is a growing sense of disapproval over using household pets in experiments. 1 New technologies have been created to replace animals in research, but the position of ideal bone substitute remains open. 6 Thus, primary research on novel models continues paramount. 7 AbstractAnimal models are live subjects applied to translational research. They provide insights into human diseases and enhance biomedical knowledge. Livestock production has favored the pace of human social development over millennia. Today's society is more aware of animal welfare than past generations. The general public has marked objections to animal research and many species are falling into disuse. The search for an ideal methodology to replace animal use is on, but animal modeling still holds great importance to human health. Bone research, in particular, has unmet requirements that in vitro technologies cannot yet fully address. In that sense, standardizing novel models remains necessary and rabbits are gaining in popularity as potential bone models. Our aim here is to provide a broad overview of animal modeling and its ethical implications, followed by a narrower focus on bone research and the role rabbits are playing in the current scenario. K E Y W O R D Sanimal experimentation, bone density, Lagomorpha, translational medical research MACEDO Et Al.

Quando fraturas ósseas ocorrem, forças externas produzem movimentação interfragmentária continuamente e um método de estabilização se faz necessário. É sabido que as condições mecânicas no local de fratura influenciam a formação de calo durante o processo de cicatrização óssea e para que cicatrização óssea primária seja obtida é necessária estabilidade absoluta no foco de fratura. O conceito de strain de Perren determina que a deformação relativa no foco de fratura estabilizado depende do tamanho da lacuna de fratura original. Fraturas redutíveis (sem cominuição) são consideradas de alto strain, pois uma pequena força aplicada a linha de fratura resulta em grande movimentação com efeito deletério ao processo de consolidação. O presente trabalho revisa a literatura disponível a respeito de fatores que influenciam a mecânica de fraturas de alto strain em medicina veterinária, seus métodos de tratamento e a física por trás dos implantes disponíveis. Cada configuração de fratura requer atenção especial e cuidado crítico na escolha do método de osteossíntese e no tipo de estabilidade necessária para que a consolidação ocorra no tempo esperado. Conhecimento da teoria do strain é mandatório para a formação de cirurgiões ortopédicos.

Traumatic events such as a motor vehicle accident or falling from heights are very common in veterinary medicine and often lead to vertebral fracture-luxation with concomitant spinal cord injuries, mostly in the thoracolumbar spine. The purpose of this cadaveric biomechanical study was to determine the feasibility of the three-column concept in canine thoracolumbar segments with induced fractures. Eighteen Functional Spinal Units (FSU) of the thoracolumbar segments (T12-L2) were collected from 18 medium-sized adult dog cadavers and were subjected to flexion-extension and lateral bending tests so that range of motion (ROM) was recorded with a goniometer. Fractures were induced by compressive loads applied by a universal testing machine (EMIC®). After this, specimens were screened using computed tomography (CT) and the fractures were graded as affecting one, two or three columns, and divided into groups A, B, and C, respectively. Post-fracture range of motion (ROM) was compared with the previous results. Groups B and C (with fractures in two or three columns) had instability in the two axes evaluated (P<0.05). The outcomes of this study support the applicability of the three-column theory to thoracolumbar spines of dogs, as the FSUs that suffered fractures in two or more columns showed axial instability.

Vertebral and spinal cord trauma are common conditions in small animal practice and often result in vertebral fractures/luxation (VFL) with concomitant spinal cord laceration, concussion, compression, or ischemia. These lesions have several clinical presentations that may vary from moderate to severe pain and partial to total loss of motor, sensory, and visceral functions, which may result in death or euthanasia. Our purpose is to describe five cases (four dogs and one cat) of complications secondary to the use of bone cement for vertebral stabilization. The patients, between five months and four years of age and weighing between 1.4 and 12.2 kg, were referred to the Small Animal Orthopedics and Traumatology Service of the Veterinary Hospital of the College of Veterinary Medicine and Animal Science of the University of São Paulo. They had a history of post-operatory polymethyl methacrylate (PMMA) reactions (such as drainage or cement exposure due to infection or implant failure) in periods from 9 to 18 months after undergoing spinal osteosynthesis. Surgical implant removal occurred in 80% of the patients (4/5). Complete remission was not observed in the patient with residual implants. The association of pins/screws and PMMA is a versatile osteosynthesis technique and is applicable in all spinal regions. However, delayed complications can occur, which could require additional surgical procedures. Despite the small number of cases included in this study, one can infer that complications related to the use of bone cement in spinal surgery can occur in the long term and should be highlighted during the implant choosing process for vertebral osteosynthesis in small animals.

Background: Intervertebral disc extrusion with consequent spinal compression or intervertebral disc disease (IVDD) is one of the most common causes of compressive myelopathy in dogs, and the thoracolumbar spine discs between T12 and L2 are most affected. Extrusions in cranial thoracic region are rare, and there is few cases in literature reporting this situations, this rarity is attributed to the presence of the intercapital ligament connecting the rib heads between T2 and T10, which strengthens this region both mechanically and anatomically. The aim of this article is report the clinical signs, diagnosis and treatment of a case of Type I Hansen IVDD between T8 and T9 in a Dachshund breed dog.Case: An 8-year-old Dachshund male dog was presented for investigation of pelvic limb incoordination and back pain, which started 10 days prior to the consultation. It had a history of a similar condition 3 months earlier that showed improvement after clinical treatment. On neurological examination was identified in both pelvic limbs proprioceptive ataxia, absence of proprioception, increased muscle tone, presence of interdigital reflex and increased patellar reflex. Cutaneous trunci reflex was absent below T11 on the left side, and pain was noted upon palpation of T7 through the T12 vertebrae. A grade II asymmetric thoracolumbar lesion with hyperesthesia was diagnosed. On suspicion of IVDD, cerebrospinal fluid (CSF) collection and CT scan analysis of the thoracolumbar region were performed. CT scan showed the presence of hyperattenuating and mineralized material, 1 cm long, on the floor of the spinal canal, mainly on the left side, occupying 80% of the diameter of the spinal canal between T8 and T9. The patient was then submitted to decompression surgery through hemilaminectomy and showed a good recovery. As the occurrence of disc extrusion in cranial thoracic region of chondrodystrophic breeds is rare, we report the clinical signs, diagnosis and treatment of a case of Type I Hansen intervertebral disc disease (IVDD) between T8 and T9 in a Dachshund breed dog.Discussion: All spinal discs can undergo a process of degeneration causing IVDD, in which the cervical and thoracolumbar regions are the most affected due to reasons not yet fully understood, however spinal cord compression between the T1 and T9 vertebrae is very rare, probably due to the strengthening provided by the intercapital ligament to the posterior annulus fibrosus. Disc extrusion in unusual locations in chondrodystrophic breeds is mainly reported as extrusion between vertebrae T1 and T2, and T9 and T10, with some cases was attributed to an anatomical abnormality of the intercapital ligament. The evaluation of intervertebral discs of the German shepherd breed dogs using MRI showed disc degeneration processes in thoracic vertebras. Disc extrusions often result in more severe clinical signs than protrusions, and occur acutely or subacutely, which was different from the case described here, maybe because the presence of the intercapital ligament permitted gradual extrusion allowing the spinal cord to adapt to the compression. Despite surgical access to this region being described as more complex due to the presence and proximity of the rib head to the vertebral body and the possibility of injuring the intercostal muscles causing pneumothorax, the hemilaminectomy and rib head excision at T9 could be performed without any complications. Thus, although unusual, the cranial thoracic region should not be overlooked as a possible site of occurrence of IVDD, since the diagnosis, treatment and prognosis are similar to those in patients with extrusions in the most common sites.Keywords: intervertebral disc degeneration, dogs, paresis, ataxia.