Intervertebral Disc Disease and
Cavalier King Charles Spaniel
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Intervertebral disc disease (IVDD) is progressive degeneration of the disks between the vertebrae of the spine. Cavalier King Charles spaniels are reportedly prone to a form of IVDD known as Hansen Type I intervertebral disk disease. IVDD is most common in the Dachshund. Another consequence of this degeneration is a chronic disorder called spondylosis.
The intervertebral disk (or disc) is a puck-shaped, shock absorbing and stabilizing cushion between most of the vertebrae (the bones of the spine). Each disk consists of a tough outer layer (fibrous tissues and cartilage, called annulus fibrosus) which surrounds a spongy inner core (gelatinus and cartilage, called nucleus pulposus).
For the typical dog, its disks may survive intact or may deteriorate very gradually over its lifetime. However, for some breeds, including the cavalier King Charles spaniel, one or more of the dog’s disks’ outer layer may start to degenerate at a younger age and progress more rapidly, causing the inner core to narrow and harden. As the degeneration of the disk progresses, the outer layer may rupture, allowing the hardened inner core to extrude (herniate) and compress the adjacent spinal cord and nerve roots, causing pressure, inflammation, and pain.
This early progression of the degenerating disc is called Hansen Type I intervertebral disk disease (IVDD) (see at right). This disorder occurs primarily in chondrodystrophic breeds (which include the Cocker spaniel, Basset hound, Beagle, bulldogs, Corgi, Dachshund, Shih-Tzu and Pekingese). Chondrodystrophy is a disorder of the formation of cartilage, which is the connective tissue between bones. The cartilage development of chondodystrophic breeds is genetically deformed, as a consequence of having been bred for shorter legs and other characteristics of dwarfism.
In reports on the subject of chondrodystrophic breeds, cavalier King Charles spaniels have been described as being either chondrodystropic-type or semi-chondrodystrophic. Regardless of where CKCSs fit within the spectrum of chondrodystrophic breeds, they suffer from Hansen Type I IVDD nearly as often as some breeds clearly identifiable as being chondrodystrophic.
In chondrodystrophic breeds, degeneration of the disks occurs as a result of this cartilage deformity, and it usually occurs at relatively young ages, such as between ages 3 and 6 years, and it tends to recur periodically, in multiple areas along the spine. It usually comes on suddenly and is very painful.
Spondylosis (spondylosis deformans) is a chronic version of disk degeneration in which bony spurs form on the spine and may grow together, connecting one vertebra with another one.
Intervertebral disk disease (IVDD) can cause a variety of symptoms, ranging from signs of mild pain to partial or complete paralysis. The most common symptom is pain, and the most common regions of the spine are the thoracolumbar (lower back area) and cervical (neck). Observable symptoms may appear suddenly, intermittently or gradually and could include:
•Stiff or arched back
•Lowered head stance
•Dragging one or more legs when walking
•Reluctance to rise
•Yelping unexpectedly when touched or moving
•Fear of being touched, protecting themselves and possibly showing aggression
•Sensitive to movement
•Stilted gait; tentative gait
•Tender or tense abdomen
•Paralysis in one or more limbs
The symptoms may progress from milder ones to more severe ones.
A veterinarian’s initial examination of a dog with symptoms of IVDD likely will include physical, orthopedic, and neurologic examinations. The exam may include x-rays (radiographs) and the vet may recommend more extensive tests, such as a myelogram, magnetic resonance imaging (MRI) or Computed tomography (CT or CAT scan). A myelogram, CT, or MRI requires that the dog be under general anesthesia.
A myelogram (right) is an x-ray of the spine, taken after the dog’s spine has been tapped and cerebrospinal fluid (CSF) has been injected with a dye, to enhance the view of the spinal cord. The procedure requires a spinal tap, and therefore the dog must be under general anesthesia. The myelogram should enable the examiner to locate the affected disk and the precise location of where the disk is impacting the nerve roots, spinal cord, or surrounding tissues. However, due to the predominance of syringomyelia in the cavalier King Charles spaniel, myelography is deemed to be risky in this breed. See this 2005 report.
Computed tomography (CT) is an x-ray technique using digital geometry processing to generate a three-dimensional image of the inside of an object from a large series of two-dimensional x-ray images taken around a single axis of rotation. It is particularly useful when combined with a myelogram, to give the examiner an independent view of the affected disc, thus eliminating the likelihood of a misinterpretation due to swelling of the injured spinal cord in the area of the disk.
Magnetic resonance imaging scanning (MRI) is the gold standard for examining herniated disks, because it provides the most detailed images of all aspects of the affected area, including the spinal cord, disks, and nerve roots. MRIs are preferred for cavaliers, due to the breed's high percentage of dogs with syringomyelia. See this 2005 report.
In an October 2014 study, infrared imaging (thermography) was 90% successful in differentiating between normal dogs and those with Type I thoracolumbar intervertebral disk disease (TLIDD), and 97% successful in identifying the abnormal intervertebral disc space in dogs with TLIVDD.
Analysis of the CSF may be performed at the time as the diagnostic imaging.
Recommended treatment may vary from confinement to surgery and all categories in between. The form of treatment depends upon the severity of the symptoms, the myelographic, MRI, or CT Images of the affected area, and the lack of success of prior, more conservative treatments.
The main goals of treatment of IVDD are to eliminate the pain and other symptoms, to prevent further disk displacement, and possibly enable the herniated disc to retreat from its displaced position or be resorbed by the body.
Recommended treatment may vary from confinement to surgery and all categories in between. The form of treatment depends upon the severity of the symptoms, the myelographic, MRI, or CT Images of the affected area, and the lack of success of prior, more conservative treatments.
The main goals of treatment of IVDD are to eliminate the pain and other symptoms, to prevent further disk displacement, and possibly enable the herniated disk to retreat from its displaced position or be resorbed by the body.
For dogs with the mildest symptoms, the most conservative care is strict cage rest, often up to a full month. Invariably, medications also will be prescribed, usually, at least initially, non-steroidal anti-inflammatory drugs (NSADs) including carprofen (Rimadyl, Quellin), meloxicam (Metacam), firocoxib (Previcox), mavacoxib (Trocoxil), and aspirin.
*Carprofen (Rimadyl, Quellin) may have serious side effects and should not be given without a veterinarian's close guidance and monitoring.
Frequently, anti-inflammatory glucocorticoids (cortisteroids) also will be prescribed, such as prednisolone (Prelone), methylprednisolone (Medrol, Medrone), and dexamethasone (Decadron, Dexamethasone Intensol, Dexone, Hexadrol). Glucocorticoids additionally may reverse some of the injury to the spinal cord. Anti-inflammatory doses of glucocorticoids should only be used in medically managed patients under strict cage confinement.
Because of potential for additive adverse side effects (especially gastrointestinal), glucocorticoids and nonsteroidal anti-inflammatory drugs should never be administered concurrently. Glucocorticoids have serious side effects, such as weight, gait, and skin changes, and harmful suppression of the immune system. Long term use of these drugs is not advised.
If muscle spasticity is detected, the vet may administer a muscle relaxant, such as methocarbamol (Robaxin) or guaifenesin (glyceryl guaiacolate). A last resort drug to reduce severe pain would be a narcotic analgesic.
Severely affected dogs, with evidence of spinal cord or nerve root compression, almost always require some form of decompressive surgery. Spinal surgery always should be performed only by a board certified veterinary surgeon or board certified veterinary neurologist. The spinal cord and nerve roots are surrounded by the protective bone which forms the vertebral canal.
The goal of decompressive surgery is to gain access to most of the spinal canal, remove a portion of the bone over the spinal canal, to allow access to the spinal cord, nerve roots, and the herniated disc material, and relieve compression on the spinal cord.
The type of surgical technique may depend upon where the affected disk is located along the spine. Surgeries which remove bone from the upper or back side of the spine are labelled laminectomies. The main decompressive procedures for disks in the neck, called the cervical area, are either a dorsal laminectomy, whereby the surgeon approaches from the back of the neck to reach the vertebrae and discs, or a ventral spondylectomy, or ventral slot procedure, whereby the entry is at the throat, displacing the trachea, esophagus and neuro-vascular trunks to the side to reach the vertebrae and disks.
For disks lower along the spine, in the thoracolumbar area, the procedures are a dorsal laminectomy, followed by a dorsal hemilaminectomy. A ventral slot, requring approaching the lower spine from the front (ventral) is not a viable option in the thoracolumbar area.
A somewhat controversial surgical procedure, called preventative fenestration may be recommended. This involves removing the degenerated center of one or more disks – often up to four to six disks – all through a single incision. It is a complex operation with an elevated risk level.
Disc replacement surgery may be an option. Dr. Filippo Adamo, board certified veterinary neurologist, has developed replacement disc implants (the Adamo Spinal Disc), which have been shown to be successful in treating disc-associated Wobbler's Syndrome. See his February 2015 article.
In some cases, non-traditional therapies such as holistic healing or homeopathy, including acupuncture (right), may be useful alternatives to conventional medicine and surgery. Acupuncture, in particular, has been successful for dogs which have signs of pain alone, or only mild neurologic deficits.
February 2015: NC State research team finds 4-Aminopyridine (4-AP and t-butyl) enable paralyzed dogs to walk, wag tails. In a December 2014 report, North Carolina State's Dr. Natasha Olby and her a team found that two potassium channel antagonists, 4-Aminopyridine (4-AP) and N- (4-pyridine) t-butyl carbamate derivative of 4-AP (T-BOC), enabled dogs with acute spinal cord injuries to walk and wag their tails, by restoring the ability to conduct nerve impulses and improving function in the injured animal.
December 2014: New drug lets paralyzed rats move after spinal cord injuries. A team of US researchers, led by Dr. Bradley Lang of Case Western Reserve University School of Medicine, state in a December 2014 report that they designed a drug, intracellular sigma peptide (ISP), which they injected beneath the skin of paralyzed rats near the spinal injury site. After spinal cord injury, axons try to cross the injury site and reconnect with other cells but are stymied by scarring that forms after the injury. Previous studies suggested their movements are blocked when the protein tyrosine phosphatase sigma (PTP sigma), an enzyme found in axons, interacts with chondroitin sulfate proteoglycans, a class of sugary proteins that fill the scars. Injected ISP blocked the enzyme and facilitated the drug’s entry into the brain and spinal cord, partially restoring axon growth and improving movements and bladder functions.
November 2014: Infrared imaging study finds 90% success in identifying dogs with Type I intervertebral disk disease. In an October 2014 study of 70 dogs by a US team of researchers led by Dr. Dominic J. Marino, they found that medical infrared imaging (thermography) was 90% successful in differentiating between normal dogs and those with Type I thoracolumbar intervertebral disk disease (TLIDD), and 97% successful in identifying the abnormal intervertebral disc space in dogs with TLIVDD.
November 2012: German researchers assess effect of gabapentin on post-operative pain after intervertebral disc surgery. In a November 2012 report in Veterinary Anaesthesia and Analgesia, involving 63 dogs, German neurologists compared the pain-relief value of gabapentin when added to opioid analgesia. They concluded that gabapentin administered orally twice a day "did not result in a detectable reduction in pain behaviour compared to background opioid analgesia alone." However, they recommend further studies to determine if the results were related to effective background analgesia or an ineffective dose of gabapentin.
July 2012: NC State studies potassium channel antagonists to treat spinal cord injuries. North Carolina State's Dr. Natasha Olby leads a team evaluating two potassium channel antagonists, 4-Aminopyridine (4-AP) and N- (4-pyridine) t-butyl carbamate derivative of 4-AP (T-BOC) as treatments of dogs with acute spinal cord injuries. Potassium channel antagonists block potassium channels on this exposed tissue, restoring its ability to conduct nerve impulses and improving function in the injured animal. Read the details here.
February 2012: NC State needs dogs for stem cell research of spinal cord injuries. Dr. Natasha Olby of North Carolina State's veterinary college is leading a clinical trial in which stem cells are injected into dogs' herniated discs. According to Dr. Olby, even in the case of severe spinal cord injury all may not be lost in terms of spinal cord function – there may still be salvageable, living nerves and nerve fibers, or axons, bridging the site of the injury that could still transmit signals if they had a little help. Dr. Olby's team target surviving nerves and axons that are still crossing the site of the injury and seek to restore their conductivity.
Often, these damaged nerves have lost the myelin sheath, fatty material that coats axons and allows them to conduct signals. Dr. Olby wants to restore the myelin sheath to these surviving axons by taking fat cells from the patient and turning them into stem cells that can be combined with nerve cells and injected into the site of the damage, regrowing the sheath. Even though she is still in the early stages of a randomized clinical trial, the results thus far are reportedly encouraging. Her team still need candidate dogs for this study. Watch a YouTube video of Dr. Olby explaining this research project here.
The project's inclusion criteria include:
• Dogs must have suffered a thoracolumbar spinal cord injury at least 3
months previously from which they have failed to recover either motor or sensory
function in their hind limbs.
• Dogs with only limited or no motor function in their hind limbs will be admitted – this will be determined at the first evaluation by the investigators.
• Dogs will have to be videotaped when walking on a treadmill and so we can only include dogs that will tolerate working with the investigators on the treadmill.
• Dogs must also be in good health other than their spinal cord injury: dogs with urinary tract infections will not be able to start the study until the infection is treated.
• The owner must be willing to come to the hospital with their dog once a week for the first month of the trial and then once a month for the remainder of the trial.
Intervertebral Disk Disease, Chapter 62, Textbook of Small Animal Orthopedics. Andy Shores. 1982; U. Penn CAL small animal orthopedics.
Spondylosis Deformans, Chapter 61, Textbook of Small Animal Orthopedics. Joseph P. Morgan, Darryl N. Biery . 1982; U. Penn CAL small animal orthopedics.
Neurological diseases of the Cavalier King Charles spaniel. C. Rusbridge. J.Sm.Ani.Pract. 2005; 46:265–272. Quote: "The CKCS is a chondrodystrophic-type breed and as such is prone to Hansen type I disc extrusions. The most common clinical sign is spinal pain, with or without paresis. Disc extrusion is uncommon in dogs younger than two years of age. Survey radiographs may indicate possible sites of disc extrusion by identifying a narrowed intervertebral disc space, foramen or joint spaces, or by finding calcified disc material within the vertebral canal. For confirmation of the diagnosis, further imaging such as myelography or magnetic resonance imaging (MRI) is required. MRI is preferred because of the tendency for CKCSs to have syringomyelia and subsequently a small cisterna magnum and subarachnoid space, presenting an increased risk of intrathecal spinal needle placement. Lumbar, as well as cisternal, myelography is risky in this breed. Management of disc disease may be medical (analgesia and exercise restriction for at least four weeks) or surgical. Surgical management is preferred for dogs with significant paresis or paralysis. For the optimum chance of return of function, dogs without deep pain perception should have decompressive surgery performed within 24 hours of loss of function."
Intervertebral Disc Disease (IVDD). Patty Khuly. Quote: "The more typical, Type I IVDD is common in the dachshund along with many other chondrodystrophic breeds of dogs including the basset hound, beagle, French bulldog, Lhasa apso, Pekingese, pomeranian, shih tzu, and Welsh corgi. Cocker spaniels, Cavalier King Charles spaniels and other semi-chondrodystrophic breeds are also predisposed."
Presumptive exercise-associated peracute thoracolumbar disc extrusion in 48 dogs. W. M. McKee, C. J. Downes, J. J. Pink, T. J. Gemmill. Vet.Rec. April 2010; 166:523-528. Quote: "Forty-eight dogs [including a cavalier King Charles spaniel] were diagnosed with presumptive exercise-associated peracute thoracolumbar disc extrusion. The median age was seven years (range two to 11 years), and median bodyweight was 23 kg (range 10 to 41 kg). The duration of signs before presentation ranged from 0.5 to four days. Twenty-nine dogs were non-ambulatory, of which 17 were incontinent and two had lost pain perception. Pelvic limbs were hyporeflexic or areflexic in 11 dogs. Intervertebral disc narrowing was evident on radiographs in 44 dogs. Myelography demonstrated a small, extradural space-occupying lesion dorsal to an intervertebral disc between T11-12 and L3-4 with adjacent spinal cord swelling. Forty-six dogs were treated non-surgically, one was euthanased and one was managed by hemilaminectomy (and subsequently euthanased). Follow-up information was available for 46 dogs 1.5 to 55 months after injury (median 22 months) showing that pelvic limb function had improved in all cases and all non-ambulatory dogs had regained the ability to walk. Six dogs remained faecally incontinent, and one dog remained urinarily and faecally incontinent."
Dorsolateral spinal cord compression at the C2-C3 junction in two Cavalier King Charles spaniels. K. P. Harris, T. C. Saveraid, and S. Rodenas. Vet. Rec. 2011;169(16):416. Quote: "Due to the high incidence of Chiari-like malformation (CM) and syringomyelia (SM) in Cavalier King Charles spaniels (CKCS), the presentation of this breed with a history of apparent neck pain often prompts an early suspicion for CM-SM. Conversely, CM-SM findings upon MRI have been reported in many asymptomatic CKCS, and thus other differentials for neck pain such as vertebral trauma, meningioencephalomyelitis or myelocompression must be exhaustively excluded. Cervical spondylomyelopathy (CSM), also referred to as cervical vertebral malformation-malarticulation syndrome, cervical vertebral stenotic myelopathy and wobbler syndrome among other terms, is a common multifactorial neurological disorder affecting mainly large/giant breed dogs. Cases of CSM have been broadly classified by their mechanism of spinal cord and/or nerve root compression as either disc-associated (DA-CSM) or osseous-associated (OA-CSM). This short communication describes dorsolateral compressive lesions of the spinal cord at the C2-C3 junction, similar to those described in giant breed dogs with OA-CSM, in two CKCS with concurrent CM, being evaluated with MRI for neck pain. To the author's knowledge, this is the first report of such MRI findings in this breed. In case 1, a 13.9 kg two-year-old male neutered CKCS presented with a three-month history of intermittent periods of apparent discomfort manifested as very abrupt rising from rest. Two weeks earlier, the owner had observed an isolated episode of ataxia during which the dog fell to the left, had a left-sided head tilt and facial twitching. The dog remained responsive to the owner throughout and returned to normal within 30 minutes. The owner also reported that the dog frequently scratched at one ear (the side unknown). Neurological and otoscopic examination revealed no abnormalities. Moderate to severe hyperaesthesia was evident upon manipulation of the cervical spine."
Intervertebral Disk Herniation. Jonathan M. Levine. NAVC Clinicians Brief. Feb 2012; 18-20. Quote: "Intervertebral disk herniation (IVDH) is abnormal displacement of the nucleus pulposus and/or annulus fibrosus into the vertebral canal or intervertebral foramen. IVDH is the most common cause of spinal cord injury in dogs; some breeds have a lifetime incidence that approaches 20%. ... Myelography, computed tomography (CT), and magnetic resonance imaging (MRI) are typically used to diagnose IVDH.All three imaging modalities can localize spinal cord compression. Many clinicians favor MRI because it is multiplanar and noninvasive, provides data associated with functional outcome, and is the only means of diagnosing certain vertebral column diseases that clinically resemble IVDH (eg, vascular myelopathies)."
Evolution of clinical signs and predictors of outcome after conservative medical treatment for disk-associated cervical spondylomyelopathy in dogs. Steven De Decker, Ingrid M. V. L. Gielen, Luc Duchateau, Anna Oevermann, Ingeborgh Polis, Iris Van Soens, Henri J. J. van Bree,Luc M. L. Van Ham. JAVMA April 2012; 240(7):848-857. Quote: "Objective—To evaluate the evolution of clinical signs and their correlation with results of magnetic resonance imaging (MRI) and transcranial magnetic stimulation (TMS) and to assess potential prognostic variables after conservative medical treatment for disk-associated cervical spondylomyelopathy (DA-CSM) in dogs. Design—Prospective cohort study. Animals—21 client-owned dogs with DA-CSM. Procedures—After neurologic grading, dogs underwent low-field MRI and TMS with measurement of onset latencies and peak-to-peak amplitudes from the extensor carpi radialis and cranial tibial muscles. Dimensions calculated from MRI images were remaining spinal cord area, spinal cord compression ratio, vertebral occupying ratio, vertebral canal height-to-body height ratio, vertebral canal height-to-body length ratio, and vertebral canal compromise ratio. Intraparenchymal signal intensity changes were graded. Dogs were reevaluated 1, 3, 6, 12, and 24 months after initial diagnosis. Results—Outcome was successful in 8 of 21 dogs. Negative outcomes were characterized by rapid progression of clinical signs. All dogs with more severe clinical signs of DA-CSM 1 month after diagnosis had unsuccessful outcomes. Outcome was associated with the remaining spinal cord area and vertebral canal compromise ratio. Prognosis was not associated with severity of clinical signs or results of TMS. There were no significant correlations among clinical signs, MRI findings, and TMS results. Conclusions and Clinical Relevance—Conservative medical treatment of DA-CSM was associated with a guarded prognosis. Selected MRI variables and clinical evolution 1 month after diagnosis can be considered prognostic indicators. The lack of correlation among clinical signs, results of diagnostic imaging, and results of electrophysiologic evaluation in dogs with DA-CSM warrants further investigation."
Incidence of intervertebral disk degeneration–related diseases and associated mortality rates in dogs. Niklas Bergknut, Agneta Egenvall, Ragnvi Hagman, Pia Gustås, Herman A. W. Hazewinkel, Björn P. Meij, Anne-Sofie Lagerstedt. J.Amer.Vet.Med.Assn. June 2012; 2240(11):1300-1309. Quote: "Objective — To determine the incidence and distribution of intervertebral disk (IVD) degeneration–related diseases in a large population of dogs of various breeds, ages, and sexes and to determine mortality rates among dogs with these diseases. Design — Epidemiological study. Sample — Insurance data for dogs with veterinary health-care and life insurance coverage (n = 665,249 and 552,120, respectively)[cavalier King Charles spaniels included]. Procedures — Insurance claim records of 1 company in Sweden were searched to identify dogs with IVD degeneration–related diseases; incidence and mortality rates were determined for affected dogs < 12 years old and < 10 years old, respectively. Only the first paid IVD degeneration–related claim for a dog was included in incidence rate calculations. Results — The incidence rate of IVD degeneration–related diseases was 27.8 (95% confidence interval [CI], 27.2 to 28.4) occurrences/10,000 dog-years at risk (DYAR), indicating that approximately 0.3% of dogs/y in this population were affected. Miniature Dachshund was the most highly represented breed, followed by Standard Dachshund and Doberman Pinscher (237.1 [95% CI, 212.9 to 261.4], 141.5 [95% CI, 135.5 to 147.4], and 88.6 [95% CI, 72.1 to 105.2] occurrences/10,000 DYAR, respectively). The incidence rate of IVD degeneration–related disease was greater in male than in female dogs and increased with age. Overall mortality rate attributed to IVD degeneration–related diseases was 9.4 (95% CI, 8.9 to 9.8) deaths/10,000 DYAR and was greater in males than in females. Conclusions and Clinical Relevance — Differences in incidence rates among various breeds suggested a genetic involvement. Knowledge of the distribution of IVD degeneration–related diseases among dogs of various breeds and ages may facilitate early diagnosis and preemptive treatments in patients at risk for developing these diseases."
Intervertebral disc disease in dogs – Part 1: A new histological grading scheme for classification of intervertebral disc degeneration in dogs. N. Bergknut, B.P. Meij, R. Hagman, K.S. de Nies, J.P. Rutges, L.A. Smolders, L.B. Creemers, A.S. Lagerstedt, H.A.W. Hazewinkel, G.C.M. Grinwis. Vet.J. July 2012. Quote: "Intervertebral disc (IVD) degeneration is common in dogs and can lead to serious disorders. Current treatments can relieve clinical signs of disease, but do not restore IVD function. The development of regenerative strategies for IVD dysfunction requires detailed knowledge of the pathogenesis of IVD degeneration and its underlying mechanisms. Histological examination of IVDs at different stages of degeneration might provide this knowledge, but as there is currently no histological grading scheme for canine IVD degeneration, the aim of this study, which is the first of a two-part series, was to design and validate an appropriate scheme. Three independent observers evaluated 35 IVDs at different stages of degeneration using the scheme. Glycosaminoglycan contents of the nucleus pulposus and macroscopic grading according to Thompson, which are considered ‘gold standards’ for IVD degeneration, were used to validate the scheme. Reproducibility was assessed by analysing the inter-observer reliability of all individual variables of the grading scheme, using a weighted κ analysis. Significant correlations were found between Thompson grading and total histological score (r = 0.94; P < 0.01) and between glycosaminoglycan content and total histological score (r = −0.72; P < 0.01). Most individual histological variables showed ‘moderate’ to ‘almost perfect’ inter-observer reliability. The high correlation with the gold standards in combination with the high reproducibility indicates that the proposed histological grading scheme is reliable and objective for classification of IVD degeneration in both chondrodystrophic and non-chondrodystrophic dog breeds."
Intervertebral disc disease in dogs – Part 2: Comparison of clinical, magnetic resonance imaging, and histological findings in 74 surgically treated dogs. Hendrik-Jan C. Kranenburg, Guy C.M. Grinwis, Niklas Bergknut, Ninke Gahrmann, George Voorhout, Herman A.W. Hazewinkel, Björn P. Meij. Vet.J. July 2012. Quote: "The relationship between intervertebral disc (IVD) disease and IVD degeneration remains unclear. The aim of the present study was to compare the clinical severity of IVD herniation (IVDH), determined with a neurological grading system, with findings of magnetic resonance imaging (MRI) and histology using grading systems for IVD degeneration in chondrodystrophic (CD; n = 37) and non-chondrodystrophic (NCD; n = 37) dogs. This study is the second part of a two-part investigation, where the first part involved the development and validation of a histological grading scheme for classification of canine IVD degeneration. IVD degeneration graded on MRI correlated significantly with IVD degeneration graded on histology, but not with pre-operative clinical signs. Hansen type 1 hernias were more common in the cervical and thoracolumbar segments and Hansen type 2 hernias were more common in the lumbosacral segment. Type 1 hernias occurred more often in CD dogs than in NCD dogs, and CD dogs were clinically more severely affected than NCD dogs. The grade of IVD degeneration on MRI was higher in CD dogs than in NCD dogs, but there was no difference between dogs with type 1 and type 2 hernias. No significant differences in histological grade were found between CD and NCD dogs or between type 1 and type 2 hernias. It was possible to conclude that IVD degeneration did not correlate with the neurological severity of IVDH. The extent of degeneration identified on MRI correlated with degeneration seen histologically. Although the MRI grading system reflected the severity of IVD degenerative changes as confirmed by histopathology, it appeared less useful in predicting the clinical implications."
Assessment of the effects of adjunctive gabapentin on postoperative pain after intervertebral disc surgery in dogs. Sonja A. Aghighi, Andrea Tipold, Marion Piechotta, Piotr Lewczuk, Sabine B.R. Kästne. Veterinary Anaesthesia and Analgesia. Nov. 2012; 39(6):636–646. Quote: "Objective: To assess the effect of adjunctive gabapentin (GBP) on pain after thoracolumbar intervertebral disc surgery in dogs. Study design Prospective, randomized, controlled, clinical, ‘blinded’ trial. Animals: Sixty-three client owned dogs undergoing hemilaminectomy. Methods: Dogs were assigned to two treatment groups. The GBP group received gabapentin 10 mg kg−1 orally every 12 hours starting before anaesthesia; the placebo (P) group received empty gelatin capsules. Background analgesia was initiated with intravenous levomethadone 0.6 mg kg−1 (as the combination ‘L-Polamivet) at anaesthesia induction, followed by a fentanyl patch and levomethadone 0.2 mg kg−1 subcutaneously every 8 hours for 24 hours. Pain was assessed by the short form of the Glasgow Composite Measure Pain Score (CMPS-SF) without the gait category, and by a Visual Analogue Scale (VAS). Serum GBP concentrations and cortisol concentrations were measured. Statistical analyses utilized chi square test, Kolmogorov-Smirnov test, two-way analysis of variances for repeated measurements, Wilcoxon test and Friedmann test as relevant. Correlations were tested by Spearman’s and Pearson’s correlation coefficient. p < 0.05 was considered significant. Results: Median CMPS-SF was lower in group GBP than in group P on days 0.5, 1, 4 and 5. However, CMPS-SF and VAS were not significantly different between groups. Both pain scores decreased significantly over time. Cortisol concentrations were not significantly different between groups. Minimum serum concentrations of GBP fell below the detection limit of 1 μg mL−1 in 6 of 29 and 7 of 28 dogs at 24 and 72 hours, respectively. Conclusions and clinical relevance: 10 mg kg−1 GBP orally twice a day did not result in a detectable reduction in pain behaviour compared to background opioid analgesia alone, although a trend to lower pain levels (p < 0.1) was present. Further studies are needed to determine if this is related to effective background analgesia or an ineffective dose of GBP."
Intervertebral disc degeneration in the dog. Part 2: Chondrodystrophic and non-chondrodystrophic breeds. Lucas A. Smolders, Niklas Bergknut, Guy C.M. Grinwis, Ragnvi Hagman, Anne-Sofie Lagerstedt, Herman A.W. Hazewinkel, Marianna A. Tryfonidou, Björn P. Meij. Vety.J. March 2013;195(3):292-299. Quote: "Dogs can be grouped into two distinct types of breed based on the predisposition to chondrodystrophy, namely, non-chondrodystrophic (NCD) and chondrodystrophic (CD). In addition to a different process of endochondral ossification, NCD and CD breeds have different characteristics of intravertebral disc (IVD) degeneration and IVD degenerative diseases. The anatomy, physiology, histopathology, and biochemical and biomechanical characteristics of the healthy and degenerated IVD are discussed in the first part of this two-part review. This second part describes the similarities and differences in the histopathological and biochemical characteristics of IVD degeneration in CD and NCD canine breeds and discusses relevant aetiological factors of IVD degeneration."
Intervertebral Disk Degeneration in Dogs: Consequences, Diagnosis, Treatment, and Future Directions. N.D. Jeffery, J.M. Levine, N.J. Olby and V.M. Stein. J.Vet.Int.Med. Nov. 2013;27(6):1318–1333. Quote: "Evidence of intervertebral disk degeneration (IVDD) is extremely common in dogs, and its prevalence increases with age. It has many important consequences because degeneration of the intervertebral disks often is a prelude to disk herniation, which can injure the spinal cord, spinal nerves, or both. This review summarizes the advances in diagnosis and treatment of IVDD that have been made since the 1950s when the first detailed description of the degenerative changes was published. It also discusses new approaches to treatment of the associated spinal cord injury and new methods by which to classify injury severity that are currently under development."
Medical Infrared Imaging (Thermography) of Type I Thoracolumbar Disk Disease in Chondrodystrophic Dogs. Brian P. Grossbard, Catherine A. Loughin, Dominic J. Marino, Leonard J. Marino, Joseph Sackman, Scott E. Umbaugh, Patrick S. Solt, Jakia Afruz, Peter Leando, Martin L. Lesser, Meredith Akerman. Vet. Surgery. Oct. 2014;43(7):869-876. Quote: "Objective: to: (1) determine the success of medical infrared imaging (MII) in identifying dogs with TLIVDD, (2) compare MII localization with magnetic resonance imaging (MRI) results and surgical findings, and (3) determine if the MII pattern returns to that of normal dogs 10 weeks after decompression surgery. Study Design: Prospective case series. Animals: Chondrodystrophic dogs (n=58) with Type I TLIVDD and 14 chondrodystrophic dogs with no evidence of TLIVDD. Methods: Complete neurologic examination, MII, and MRI studies were performed on all dogs. Dogs with type I TLIVDD had decompressive surgery and follow-up MII was performed at 10 weeks. Pattern analysis software was used to differentiate between clinical and control dogs, and statistical analysis using anatomic regions of interest on the dorsal views were used to determine lesion location. Recheck MII results were compared with control and pre-surgical images. Results: Computer recognition pattern analysis was 90% successful in differentiating normal dogs from dogs affected by TLIVDD and 97% successful in identifying the abnormal intervertebral disc space in dogs with TLIVDD. Statistical comparisons of the ROI mean temperature were unable to determine the location of the disc herniation. Recheck MII patterns did not normalize and more closely resembled the clinical group. Conclusions: MII was 90% successful differentiating between normal dogs and 97% successful in identifying the abnormal intervertebral disc space in dogs with TLIVDD. Abnormal intervertebral disc space localization using ROI mean temperature analysis was not successful. MII patterns 10 weeks after surgery do not normalize."
Disc Prostheses: Cervical Disc Arthroplasty. Filippo Adamo. ACVS. October 2014.
Modulation of the proteoglycan receptor PTPσ promotes recovery after spinal cord injury. Bradley T. Lang, Jared M. Cregg, Marc A. DePaul, Amanda P. Tran, Kui Xu, Scott M. Dyck, Kathryn M. Madalena, Benjamin P. Brown, Yi-Lan Weng, Shuxin Li, Soheila Karimi-Abdolrezaee, Sarah A. Busch, Yingjie Shen, Jerry Silver. Nature. December 2014. Quote: "Contusive spinal cord injury leads to a variety of disabilities owing to limited neuronal regeneration and functional plasticity. It is well established that an upregulation of glial-derived chondroitin sulphate proteoglycans (CSPGs) within the glial scar and perineuronal net creates a barrier to axonal regrowth and sprouting. Protein tyrosine phosphatase σ (PTPσ), along with its sister phosphatase leukocyte common antigen-related (LAR) and the nogo receptors 1 and 3 (NgR), have recently been identified as receptors for the inhibitory glycosylated side chains of CSPGs. Here we find in rats that PTPσ has a critical role in converting growth cones into a dystrophic state by tightly stabilizing them within CSPG-rich substrates. We generated a membrane-permeable peptide mimetic of the PTPσ wedge domain that binds to PTPσ and relieves CSPG-mediated inhibition. Systemic delivery of this peptide over weeks restored substantial serotonergic innervation to the spinal cord below the level of injury and facilitated functional recovery of both locomotor and urinary systems. Our results add a new layer of understanding to the critical role of PTPσ in mediating the growth-inhibited state of neurons due to CSPGs within the injured adult spinal cord."
Potassium Channel Antagonists 4-Aminopyridine and the T-Butyl Carbamate Derivative of 4-Aminopyridine Improve Hind Limb Function in Chronically Non-Ambulatory Dogs; A Blinded, Placebo-Controlled Trial. Ji-Hey Lim, Audrey C. Muguet-Chanoit, Daniel T. Smith, Eric Laber, Natasha J. Olby. PLOS One. December 2014. Quote: "4-Aminopyridine (4-AP) blocks voltage gated potassium channels, restoring conduction to demyelinated axons and improving function in demyelinating conditions, but its use is associated with adverse effects and benefit in spinal cord injury is limited. Derivatives of 4-AP have been developed to improve clinical efficacy while reducing toxicity. We compared the therapeutic effects of orally administered 4-AP and its t-butyl carbamate derivative (t-butyl) with placebo in dogs that had suffered an acute spinal cord injury that left them chronically paralyzed. Nineteen dogs were entered into the trial, conducted in two-week treatment blocks starting with placebo, followed by random assignment to 4-AP or t-butyl, a washout and then the opposite medication followed by placebo. Investigators and owners were blinded to treatment group. Primary outcome measures included open field gait score (OFS), and treadmill based stepping score and regularity index, with additional secondary measures also considered. Thirteen of 19 dogs completed the protocol. Two were euthanized due to unrelated heath problems, two developed side effects and two were unable to complete for unrelated reasons. Dogs showed significant improvement in supported stepping score (from 17.39 to 37.24% with 4-AP; 16.85 to 29.18% with t-butyl p<0.0001) and OFS (from 3.63 to 4.73 with 4-AP; 3.78 to 4.45 with t-butyl, p = 0.005). Response was individually variable and most dramatic in three dogs that were able to walk without support with treatment. No significant difference was found between 4-AP and t-butyl. No adverse effects were reported with t-butyl but gastrointestinal upset and seizures were observed in two dogs with 4-AP. In conclusion, both 4-AP and t-butyl significantly improved supported stepping ability in dogs with chronic spinal cord injury with no adverse effects noted with t-butyl. Drug response varied widely between individuals, highlighting the need to understand the factors that influence canine and human patients' response to therapy."
Will There be a Role for Disc Prostheses in Small Animals? Filippo Adamo and Franck Forterre. In, Advances in Intervertebral Disc Disease in Dogs and Cats, First Edition. Edited by James M. Fingeroth and William B. Thomas. John Wiley & Sons, Inc. February 2015.