Martijn Beukers

COMPUTED TOMOGRAPHIC CHARACTERISTICS OF PRESUMED NORMAL CANINE ABDOMINAL LYMPH NODES

Though identification of lymph nodes is essential in staging cancer patients, little has been reported about the CT features of canine abdominal lymph nodes. The purpose of this retrospective study was to describe the visibility, location, and characteristics of abdominal lymph nodes in abdominal CT studies of dogs considered unlikely to have lymphadenopathy. The relationship between the number of identified lymph nodes and intraabdominal fat ranking, body weight, and slice thickness was also investigated. A total of 19 dogs were included. At least two jejunal lymph nodes and both left and right medial iliac lymph nodes were identified in all dogs. Colic lymph nodes were not identified in any of the dogs. Visualization of all other lymph nodes varied. There were significantly more lymph nodes visible in dogs with more intraabdominal fat (P < 0.0001). No correlation between the number of identified lymph nodes and body weight (P = 0.64) or slice thickness (P = 0.76) was found. Though most of all identified lymph nodes had an elongated shape, a rounded shape was most common in splenic, pancreaticoduodenal, renal, ileocolic and caudal mesenteric lymph nodes. Most lymph nodes had a homogeneous structure before and following the intravenous administration of contrast medium. Some lymph nodes had a slightly irregular structure or were relatively more hyper attenuating in the periphery than centrally before and/or after contrast administration. Mean attenuation before contrast was 37 Hounsfield Units (HU) (range 20-52 HU), and 109 HU after contrast (range 36-223 HU). Findings indicated that the CT visibility, characteristics of different abdominal lymph nodes may be variable in dogs.

Novel B19-Like Parvovirus in the Brain of a Harbor Seal

Using random PCR in combination with next-generation sequencing, a novel parvovirus was detected in the brain of a young harbor seal (Phoca vitulina) with chronic non-suppurative meningo-encephalitis that was rehabilitated at the Seal Rehabilitation and Research Centre (SRRC) in the Netherlands. In addition, two novel viruses belonging to the family Anelloviridae were detected in the lungs of this animal. Phylogenetic analysis of the coding sequence of the novel parvovirus, tentatively called Seal parvovirus, indicated that this virus belonged to the genus Erythrovirus, to which human parvovirus B19 also belongs. Although no other seals with similar signs were rehabilitated in SRRC in recent years, a prevalence study of tissues of seals from the same area collected in the period 2008-2012 indicated that the Seal parvovirus has circulated in the harbor seal population at least since 2008. The presence of the Seal parvovirus in the brain was confirmed by real-time PCR and in vitro replication. Using in situ hybridization, we showed for the first time that a parvovirus of the genus Erythrovirus was present in the Virchow-Robin space and in cerebral parenchyma adjacent to the meninges. These findings showed that a parvovirus of the genus Erythrovirus can be involved in central nervous system infection and inflammation, as has also been suspected but not proven for human parvovirus B19 infection.

Intradiscal application of a PCLA–PEG–PCLA hydrogel loaded with celecoxib for the treatment of back pain in canines : What's in it for humans?

Chronic low back pain is a common clinical problem in both the human and canine population. Current pharmaceutical treatment often consists of oral anti‐inflammatory drugs to alleviate pain. Novel treatments for degenerative disc disease focus on local application of sustained released drug formulations. The aim of this study was to determine safety and feasibility of intradiscal application of a poly(ε‐caprolactone‐co‐lactide)‐b‐poly(ethylene glycol)‐bpoly(ε‐caprolactone‐co‐lactide) PCLA–PEG–PCLA hydrogel releasing celecoxib, a COX‐2 inhibitor. Biocompatibility was evaluated after subcutaneous injection in mice, and safety of intradiscal injection of the hydrogel was evaluated in experimental dogs with early spontaneous intervertebral disc (IVD) degeneration. COX‐2 expression was increased in IVD samples surgically obtained from canine patients, indicating a role of COX‐2 in clinical IVD disease. Ten client‐owned dogs with chronic low back pain related to IVD degeneration received an intradiscal injection with the celecoxib‐loaded hydrogel. None of the dogs showed adverse reactions after intradiscal injection. The hydrogel did not influence magnetic resonance imaging signal at long‐term follow‐up. Clinical improvement was achieved by reduction of back pain in 9 of 10 dogs, as was shown by clinical examination and owner questionnaires. In 3 of 10 dogs, back pain recurred after 3 months. This study showed the safety and effectiveness of intradiscal injections in vivo with a thermoresponsive PCLA–PEG–PCLA hydrogel loaded with celecoxib. In this set‐up, the dog can be used as a model for the development of novel treatment modalities in both canine and human patients with chronic low back pain.

Surgical treatment of a cerebral brain abscess in a cat

A nine-year-old male castrated European Shorthair cat was presented with a six-day history of progressive depression and ataxic gait. Neurological examination revealed depression, absent menace in the left eye, absent pupillary light reflex in the right eye, anisocoria, circling to the right, and delayed proprioception in all limbs. Magnetic resonance imaging showed a space-occupying right temporal lobe lesion adjacent to a small defect in the temporal bone suggestive of a meningo-encephalitis with concurrent abscess formation. The site was surgically approached by a rostrotentorial craniectomy. A cerebral abscess was found and debrided. Histopathological examination of the removed tissue demonstrated a subacute to chronic purulent encephalitis with extensive necrosis of brain tissue. Neurological symptoms resolved completely within two weeks and full recovery was observed four weeks after surgery.

Biologic canine and human intervertebral disc repair by notochordal cell-derived matrix : From bench towards bedside

The socioeconomic burden of chronic back pain related to intervertebral disc (IVD) disease is high and current treatments are only symptomatic. Minimally invasive strategies that promote biological IVD repair should address this unmet need. Notochordal cells (NCs) are replaced by chondrocyte-like cells (CLCs) during IVD maturation and degeneration. The regenerative potential of NC-secreted substances on CLCs and mesenchymal stromal cells (MSCs) has already been demonstrated. However, identification of these substances remains elusive. Innovatively, this study exploits the regenerative NC potential by using healthy porcine NC-derived matrix (NCM) and employs the dog as a clinically relevant translational model. NCM increased the glycosaminoglycan and DNA content of human and canine CLC aggregates and facilitated chondrogenic differentiation of canine MSCs in vitro. Based on these results, NCM, MSCs and NCM+MSCs were injected in mildly (spontaneously) and moderately (induced) degenerated canine IVDs in vivo and, after six months of treatment, were analyzed. NCM injected in moderately (induced) degenerated canine IVDs exerted beneficial effects at the macroscopic and MRI level, induced collagen type II-rich extracellular matrix production, improved the disc height, and ameliorated local inflammation. MSCs exerted no (additive) effects. In conclusion, NCM induced in vivo regenerative effects on degenerated canine IVDs. NCM may, comparable to demineralized bone matrix in bone regeneration, serve as ‘instructive matrix’, by locally releasing growth factors and facilitating tissue repair. Therefore, intradiscal NCM injection could be a promising regenerative treatment for IVD disease, circumventing the cumbersome identification of bioactive NC-secreted substances.

Temporary Segmental Distraction in a Dog with Degenerative Lumbosacral Stenosis

OBJECTIVES  Degenerative lumbosacral stenosis (DLSS) is characterized by intervertebral disc degeneration and causes lower back pain in dogs. Temporary distraction in rabbit models with induced intervertebral disc degeneration showed signs of intervertebral disc repair. In the present study, we assessed safety and efficacy of temporary segmental distraction in a dog with clinical signs of DLSS. METHODS  Distraction of the lumbosacral junction by pedicle screw-rod fixation was applied in a 5-year-old Greyhound with DLSS and evaluated by radiography, magnetic resonance imaging, and force plate analysis before and after distraction. RESULTS  Safe distraction of the lumbosacral junction was demonstrated, with improvement of clinical signs after removal of the distraction device. Signal intensity of the intervertebral disc showed no changes over time. T2 value was highest directly after removal of the distraction device but decreased by 10% of the preoperative value at 9 months of follow-up. Disc height decreased (8%) immediately after removal of the distraction device, but recovered to the initial value. A decrease in the pelvic/thoracic propulsive force during pedicle screw-rod fixation and distraction was demonstrated, which slowly increased by 4% compared with the initial value. CLINICAL SIGNIFICANCE  Temporary pedicle screw-rod fixation in combination with distraction in a dog with DLSS was safe, improved clinical signs and retained disc height at 9 months of follow-up.

Intradiscal delivery of celecoxib-loaded microspheres restores intervertebral disc integrity in a preclinical canine model

ABSTRACT Low back pain, related to degeneration of the intervertebral disc (IVD), affects millions of people worldwide. Clinical studies using oral cyclooxygenase‐2 (COX‐2) inhibitors have shown beneficial effects, although side‐effects were reported. Therefore, intradiscal delivery of nonsteroidal anti‐inflammatory drugs can be an alternative treatment strategy to halt degeneration and address IVD‐related pain. In the present study, the controlled release and biologic potency of celecoxib, a selective COX‐2 inhibitor, from polyesteramide microspheres was investigated in vitro. In addition, safety and efficacy of injection of celecoxib‐loaded microspheres were evaluated in vivo in a canine IVD degeneration model. In vitro, a sustained release of celecoxib was noted for over 28 days resulting in sustained inhibition of inflammation, as indicated by decreased prostaglandin E2 (PGE2) production, and anti‐catabolic effects in nucleus pulposus (NP) cells from degenerated IVDs on qPCR. In vivo, there was no evidence of adverse effects on computed tomography and magnetic resonance imaging or macroscopic evaluation of IVDs. Local and sustained delivery of celecoxib prevented progression of IVD degeneration corroborated by MRI, histology, and measurement of NP proteoglycan content. Furthermore, it seemed to harness inflammation as indicated by decreased PGE2 tissue levels and decreased neuronal growth factor immunopositivity, providing indirect evidence that local delivery of a COX‐2 inhibitor could also address pain related to IVD degeneration. In conclusion, intradiscal controlled release of celecoxib from polyesteramide microspheres prevented progression of IVD degeneration both in vitro and in vivo. Follow‐up studies are warranted to determine the clinical efficacy of celecoxib‐loaded PEAMs in chronic back pain. Graphical abstract Figure. No caption available.

Intradiscal Injection of a Slow Release Formulation of Celecoxib for the Treatment of Dogs with Low Back Pain

Introduction Intervertebral disc (IVD) disease characterized by low back pain is common in both humans and large breed dogs. Inflammatory mediators such as prostaglandin E2 (PGE2) play a key role in IVD degeneration, causing structural changes of the IVD and low back pain. The current conservative and surgical treatment modalities do not reverse IVD degeneration and have certain drawbacks. Long term systemic administration of non-steroidal anti-inflammatory drugs can cause gastro-intestinal side effects. Decompressive surgery is effective in over 80% of the patients, but is rather costly and has a long recovery period. Injectable formulations that enable local sustained release of anti-inflammatory drugs aim at decreasing inflammation and thereby inhibiting degeneration and pain. In vitro, controlled release of celecoxib, a COX-2 inhibitor, from a thermoreversible acetyl-capped PCLA-PEG-PCLA hydrogel inhibited PGE2 production and enhanced matrix production for 28 days in 3D culture of canine nucleus pulposus cells that were subjected to the catabolic effects of TNF-α. In vivo, sustained release of celecoxib by the hydrogel for up to 60 days was shown and safely applied intradiscally in laboratory dogs with naturally occurring IVD degeneration. The aim of the present study is to report the safety and feasibility of intradiscal application in client-owned dogs with low back pain related to IVD degeneration. Material and Methods Client-owned dogs with low back pain were diagnosed by MRI with degenerative lumbosacral stenosis marked by mild to moderate IVD degeneration and protrusion. The dogs were surgical candidates but were offered intradiscal injection. The PCLA-PEG-PCLA thermogel, loaded with 0.013mg/ml celecoxib, was percutaneously injected into the nucleus pulposus of L7-S1 under fluoroscopy guidance. Follow-up consisted of clinical examination, owner questionnaires, and objective gait analysis by measurement of ground reaction forces (GRFs) using force plate analysis (FPA) at 6 weeks, and 3 and 6 months after injection. MRI was repeated after 3 months and included T2- and T1-weighted images and T2-mapping. Results Ten dogs with DLLS were injected with the celecoxib-loaded hydrogel. None of the dogs showed adverse reactions after intradiscal injection. Follow up MRI showed no worsening of the IVD degeneration. Clinical improvement was achieved by reduction of low back pain in 9/10 dogs, as was shown by clinical examination, force plate analysis and owner questionnaires. In 3/10 dogs low back pain recurred at 3 months and they subsequently underwent standard-of-care surgical treatment. Conclusion This study showed the safety and feasibility of intradiscal injections with a thermoresponsive hydrogel loaded with celecoxib. Ongoing studies concentrate on the long term clinical follow up of these patients. Future studies will determine the optimal loading dose of celecoxib for clinical efficacy. In this setup, the dog can be used as a model for the development of novel treatment modalities in both canine and human patients with chronic low back pain.