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Paul Freeman

My research is focused on intervertebral disc disease in dogs. Currently I have a PhD student funded jointly by the Kennel Club Charitable Trust (KCCT), BSAVA Petsavers, Debs Foundation and Dachshund Health UK. I also have an MPhil student partly funded by KCCT and the Alice Noakes Trust. Both students are co-supervised by my colleague from the pathology department Kate Hughes

Thoracolumbar intervertebral disc herniation (TL IVDH) is known to have a lifetime prevalence of ~20% in the Miniature Dachshund, and is fatal in 25% of cases. There is a perception that dogs which are more severely affected require decompressive surgery to recover ambulation, and a small amount of evidence to support this. The severe clinical signs are distressing to owners and further compounded by high financial costs of cross sectional imaging and surgery. It is however known that some dogs will recover without the need for surgery, and in 2017 I carried out an extensive data mining exercise which showed that recovery rates of  dogs suffering from TL IVDH treated with medical therapy are similar to those following surgical management in all grades of severity except the most severely affected dogs (Freeman and Jeffery, JSAP 2017: 58, 199-204).

My PhD student is studying dogs rendered non-ambulatory following acute TL IVDH and treated medically rather than surgically; these dogs receive an MRI scan to confirm diagnosis, followed by a second scan after three months of medical management. It is known that in some cases both in human and canine disc herniation the herniated material is removed by natural processes (Argent et al 2019) and we aim to document the frequency with which this occurs, and whether there is a correlation with recovery of ambulation. A pressure sensor mat (Tekscan) will be used to monitor the recovery of  dogs treated medically as well as surgically in the hospital with the aim of establishing a more objective way to evaluate recovery of co-ordination and strength of gait which could be used to compare different treatment modalities.

We aim to provide answers to a number of questions:

  • Can dogs rendered non-ambulatory following acute compressive thoracolumbar intervertebral disc herniation (TL IVDH) recover ambulation without decompressive surgery?
  • By what mechanism may herniated intervertebral disc material be removed by natural processes from the vertebral canal in dogs treated conservatively for TL IVDH?
  • Is recovery of ambulation and/or speed of recovery associated with removal of extruded disc material from the vertebral canal?

Ultimately we aim to provide an answer to the key question: In dogs suffering acute severe TL IVDH, which cases genuinely require surgical treatment, and which may recover just as well with medical management

There are many other unanswered questions surrounding the role of calcification in the pathogenesis of intervertebral disc extrusion in dogs as well as humans. Some of the key questions we have are:

  • Why do certain specific discs tend to extrude commonly, whereas others rarely do?
  • Why do some extrusions cause calamitous irreversible spinal cord injury, whereas others only lead to minimal self-limiting pain?
  • Why should disc calcification lead to an increased risk of disc extrusion?

Additional work being carried out currently by my MPhil student with the assistance of Jonathan Powell’s biominerals laboratory  is aimed at identifying the role of calcification in IVDH. Several studies have attempted to investigate the role of calcification in human disc herniation (Grant et al 2016, Shao et al 2016), and we have begun to look more closely into the mineral analysis of extruded and non-extruded disc material. Our early results indicate, as expected, a very high level of calcium and phosphorous in extruded disc material removed from the vertebral canal of clinical cases, and we are now trying to establish a valid method to look at the nature of the calcified material in this material.

We aim compare calcification in extruded and non-extruded disc material,as well as in non-degenerate discs, looking for reasons why some discs extrude and others do not, and why some extrusions are so catastrophic but others relatively benign.

Finally we are involved in a newly launched Kennel Club screening scheme for Dachshunds which provides guidelines for breeding based on the numbers of calcified discs identified by radiography. We are able to offer a CT scan alongside the radiographs, a much more sensitive modality for identification of disc calcification, with the aim of following these dogs and assessing their likelihood of suffering IVDH later in life.

In addition to this work, I am collaborating with the work of bioengineer George Malliaras and Christopher Proctor, who have designed an electrical stimulation device intended to deliver an oscillating electrical field to injured spinal cord. Our aim is to implant a series of such devices onto the surface of the injured spinal cord in a series of dogs suffering acute severe injury as a result of intervertebral disc disease.This type of stimulation has been shown in both dogs and humans to improve recovery in severe spinal cord injury, but currently no commercially available stimulator is in use. This technology has the potential to improve outcomes in both dogs and people suffering severe spinal cord injury.

 

Significant publications:

Freeman P, Jeffery ND. Re-opening the window on fenestration as a treatment for acute thoracolumbar intervertebral disc herniation in dogs. J Small Anim Pract. 2017 Apr;58(4):199-204. doi: 10.1111/jsap.12653. PMID: 28276121.

Jeffery ND, Freeman PM. The Role of Fenestration in Management of Type I Thoracolumbar Disk Degeneration. Vet Clin North Am Small Anim Pract. 2018 Jan;48(1):187-200. doi: 10.1016/j.cvsm.2017.08.012. Epub 2017 Oct 23. PMID: 29074336.

Harris G, Freeman P. Introduction of Disc Material into the Vertebral Canal by Fenestration of Thoracolumbar Discs Following Decompressive Surgery. Vet Comp Orthop Traumatol. 2020 Jan;33(1):66-70. doi: 10.1055/s-0039-1700554. Epub 2019 Nov 22. PMID: 31756749.

Hare C, Sanchini L, Worrall C, Van Poucke S, Alves L, Restif O, Freeman P. Rapid in-house method of CSF analysis utilising sedimentation direct from the spinal needle. J Small Anim Pract. 2019 Aug;60(8):486-492. doi: 10.1111/jsap.13010. Epub 2019 Apr 26. PMID: 31025384.

Freeman PM, Holmes MA, Jeffrey ND, Granger N. Time requirement and effect on owners of home-based management of dogs with severe chronic spinal cord injury.  Journal of Veterinary Behavior (2013), 8(6): 439-443

Monforte Monteiro SR et al, “Medical management of spinal epidural empyema in five dogs”. Journal of the American Veterinary Medicine Association (2017) 249, 10: 1180-1186.

Cashmore RG, Harcourt-Brown TR, Freeman PM, Jeffery ND, Granger N. Clinical diagnosis and treatment of suspected neuropathic pain in three dogs. Australian Veterinary Journal (2009), 87(1): 45-50.

Serrano G, Freeman P. Neosporosis presenting as temporal muscle atrophy in a dog. Veterinary Record Case Reports Mar 2017, 5 (1) e000380; DOI: 10.1136/vetreccr-2016-000380

Kortum A, Freeman P. Fibrocartilaginous embolism and marked cerebrospinal fluid pleocytosis in a dog. Veterinary Record Case Reports May 2018, 6 (2) e000608; DOI: 10.1136/vetreccr-2018-000608

Argent V, Fraser A, Alves L, Freeman P. Spontaneous regression of a cervical intervertebral disc extrusion in French bulldogs documented on MRI after medical management. Veterinary Record Case Reports Apr 2019, 7 (2) e000817; DOI: 10.1136/vetreccr-2019-000817

Clarke N, Harris G, Greville-Heygate O,Constantino-Casas F, Freeman P. Spinal cord clear cell meningioma in a dog. Veterinary Record Case Reports Jul 2020, 8 (3) e001118; DOI: 10.1136/vetreccr-2020-001118

Freeman P. Sacrococcygeal intervertebral disc extrusion in a Dachshund. Veterinary Record (2010), 167(16): 618-9

Freeman PM, Harcourt-Brown TR, Jeffery ND, Granger N. Electrophysiologic evidence of polyneuropathy in a cat with signs of bilateral brachial plexus neuropathy. J Am Vet Med Assoc. 2009 Jan 15;234(2):240-4. doi: 10.2460/javma.234.2.240. PMID: 19210244.

 

 

 

 

Principal Clinical Neurologist

European & RCVS Specialist in Veterinary Neurology

pf266@cam.ac.uk

Group Members:

Kate Hughes (Co-supervisor),

Jonathan Powell’s Biominerals Laboratory

George Malliaras’ Bioengineering Laboratory

Sam Khan (PhD student)

Theresa Banu Yenen (MPhil student)

The Clinical Neurology Team

 


Plain English

Canine intervertebral disc disease (‘slipped discs’) is very common especially within certain breeds. The severe clinical signs are distressing to owners and further compounded by potentially high financial costs of treatment. Although it is known many such affected dogs could recover without surgery, it is currently difficult for veterinarians to this. It is likely some dogs are being euthanised when they could be recovered, and others undergo surgery when they could have recovered with medical management. The major part of our research aims to define which of these dogs really benefit from surgical treatment.

Additional work is aimed at a better understanding of what lies behind the process of slipped discs (mineral analysis), and producing guidelines which may help to reduce the incidence of this disease (X-ray and CT screening).

I am working with a bioengineering team in design of an electrical stimulator to improve recovery in the most severely affected dogs with slipped discs, and spinal cord injury in general. This is an exciting area with potential implications for treatment of human spinal cord injury.

Grants

Kennel Club Charitable Trust

Dachshund Health UK

BSAVA Petsavers

The Debs Foundation

The Alice Noakes Trust