Electromyography in the localization of spinal cord and nerve root neoplasia in dogs and cats.

In 8 cases (6 dogs and 2 cats) of spinal cord and nerve root neoplasia, electromyography was used to localize the area of involvement. The locations of the lesions were confirmed at necropsy.     

Prevalence of diseases of the spinal cord of cats

A retrospective review of records of 205 cats with histologically confirmed disease of the spinal cord was performed to identify the prevalence of disease in this nonrandomly selected population of cats. Clinical records were reviewed, and age, duration of neurologic illness, and clinical and histopathologic findings in cats with spinal cord disease were abstracted. Disease processes were classified into 7 categories and 23 groups. The most common diseases affecting the spinal cord of cats were feline infectious peritonitis (FIP), lymphosarcoma (LSA), and neoplasia of the vertebral column secondarily affecting the spinal cord. Information on age, onset and duration of clinical signs, and lesion localization at the postmortem examination in cats belonging to the 7 categories of disease were analyzed to create a practical list of differential diagnoses. Cats were also subcategorized into 3 groups based on their age at death. FIP was the most common disease of cats younger than 2 years of age. LSA and vertebral column neoplasia were the most common diseases affecting cats between 2 and 8 years of age. Vertebral column neoplasia was the most common disease affecting cats older than 8 years of age. Results of this histopathologic study showed that FIP and LSA were the most common disease processes affecting the spinal cord of cats. However, at least 21 other groups of diseases and their relative prevalence were identified.     

Arterial supply to the rat colon

Rats are often used as animal models in studies such as on intestinal transplantation and anastomosis healing, which require colectomy. Although detailed information regarding arterial supply is important to establish accurate and reproducible experimental procedures, this has not been studied in the rat colon. Therefore, we analysed the detailed arterial distribution pattern and its individual variations in the colon of 34 rats. The rat colon received colic branches of the ileocolic artery, and the right, middle and left colic arteries. The single left colic artery constantly arose from the caudal mesenteric artery and was distributed to the descending colon, whereas the others showed variations in number and distribution. The ileocolic artery gave rise to one (12%) or two (88%) colic branches supplying the proximal ascending colon, and these branches formed rich, mesh-like anastomoses along the initial portion of the ascending colon. One (74%) or two (26%) right colic arteries originated from the cranial mesenteric artery and supplied the ascending colon and right colic flexure. Moreover, one (38%), two (56%) or three (6%) middle colic arteries emerged from the cranial mesenteric artery and were distributed to the transverse colon, left colic flexure and proximal descending colon. In total, we categorized the individual variations in arterial branching and anastomosis into 11 patterns. Arterial supply to the rat colon showed a specific pattern and frequent individual variations. These findings thus provide essential information for establishing reproducible models of rat colic surgery.     

Anatomical study of blood supply to the cervical spinal cord in the guinea pig

The aim of this study was to describe the arterial arrangement of the cervical spinal cord in the guinea pig. The study was carried out on 20 adult English self guinea pigs using corrosion and dissection technique. Batson's corrosion casting kit no. 17^© was used as a casting medium. The origin of the ventral spinal artery from the left vertebral artery was found on average in 35% of the cases and from the right vertebral artery on average in 40% of the cases. The ventral spinal artery with origin from the anastomosis of two medial branches was found on average in 25% of the cases. The presence of ventral radicular branches of rami spinales entering the ventral spinal artery in the cervical region was observed in 42% of the cases on the right side and in 58% of the cases on the left side. The presence of dorsal radicular branches of rami spinales that reached the spinal cord was observed in 63% of the cases on the left side and in 37% of the cases on the right side. The number of radicular branches supplying the spinal cord is greater in guinea pig than in humans.     

Fecal incontinence and spinal cord abnormalities in seven dogs

Seven dogs with fecal incontinence and abnormal gaits were evaluated. Fecal incontinence was characterized as defecation of normal stools without posturing. Duration of clinical signs prior to evaluation ranged from 5 months to 3 years. Five dogs had upper motor neuron (UMN) paraparesis, and 2 dogs had UMN tetraparesis. With magnetic resonance imaging, spinal cord abnormalities primarily involving the dorsal aspect of the spinal cord were identified in all dogs. Five dogs had focal abnormalities, and 2 dogs had diffuse abnormalities of the spinal cord. Of the dogs with focal spinal cord lesions, 4 had cystic spinal cord abnormalities and 1 had a meningioma. Surgery was performed on all dogs with focal lesions; 4 of the 5 dogs had resolution of fecal incontinence after surgery. Results in these dogs suggest that fecal incontinence can be associated with spinal cord abnormalities and, depending on the characteristics of the lesion, can resolve after surgical treatment of the abnormality.     

Intramedullary cavernous malformation of the spinal cord in two dogs

Intramedullary cavernous malformations (CVMs) of the spinal cord were diagnosed in 2 adult dogs that presented for paraparesis. An intramedullary spinal cord lesion was identified on a myelogram in the first dog, and expansion of the vertebral canal was evident on radiographs in the second. Extensive intraparenchymal hemorrhage was found on gross postmortem examination in both dogs, and a distinct lobulated intramedullary mass was evident in the second dog. Microscopically, both lesions were composed of dilated, thin-walled vascular channels with little-to-no intervening neural parenchyma. Both dogs had evidence of channel thrombosis along with perilesional hemorrhage and hemosiderin accumulation. The second dog had additional degenerative changes, including thickened fibrous channel walls with hyalinization, foci of mineralization, and occasional tongues of entrapped gliotic neuropil. CVMs appear to be an uncommon cause of both acute and chronic spinal cord disease in the dog.     

Amplitude and latency characteristics of spinal cord motor-evoked potentials in dogs

The motor-evoked potential can be reliably recorded in anesthetized dogs by use of percutaneous placement of active recording electrodes near the dorsal lamina of the vertebral column. Two types of responses were observed in this study; short (less than 5.5 ms at T9-10)- and long (greater than 5.8 ms at T9-10)-latency waves. Short-latency waves are larger in amplitude and appear with higher stimulus intensities than do long-latency waves. Short-latency waves are conducted at greater than 80 m/s and may not reflect pyramidal tract activation. The safety of using higher intensity stimuli to generate short-latency waves has not been determined.     

Percutaneous recording of evoked spinal cord potentials of dogs.

Using a signal-averaging system, potentials evoked by stimulation of nerves in the limbs or tail of dogs were recorded through needle electrodes placed adjacent to the vertebral column. Cord dorsum potentials (consisting of a small triphasic wave followed by a large negative peak and a subsequent slow positive phase) were recorded at the level of the lumbar enlargement after stimulating nerves in the pelvic limb or tail, and at the cervical enlargement after forelimb nerve stimulation. Ascending volleys were recorded from appropriate levels of the spinal cord or from regions of the cauda equina. After forelimb nerve stimulation, a large slow potential, reflecting activation of an unidentified neuronal pool, was recorded at the level of the first cervical vertebra. Percutaneously recorded potentials were closely similar to those recorded directly from the dura mater, suggesting that the method accurately recorded spinal cord electrical events and, therefore, might be of use in studying clinical or experimental spinal cord disease.     

Osteological features in pure-bred dogs predisposing to thoracic or lumbar spinal cord compression

Consistent with those vertebral sites most commonly clinically affected by spinal cord compression, body size normalised midsagittal diameters of the caudal vertebral foramen limits T10-T12 were significantly (P<0.05) lower in Dachshunds relative to other breeds. Minimal midsagittal diameters in Yorkshire Terriers and Maltese were noted at T11cd/12cr. However, these diameters were always larger (P<0.05) in small breeds compared to those in Dachshunds and large breeds suggesting that the small breeds investigated are at lower risk of developing clinical signs if a compressive disease occurs at that site. In large breeds, minimal values were present at L1cd/L2cr and in agreement with clinical findings correlate with those spinal sites most susceptible to spinal cord compression in nonchondrodystrophic large breeds. Caudal displacement of the lumbosacral enlargement of the spinal cord relative to the position previously noted in large breeds was confirmed for the Dachshunds and 50% of small breeds. However, caudal displacement was also noticed in the German Shepherd dogs.     

Surgical treatment of intramedullary spinal cord neoplasia in two dogs

An area of intramedullary spinal cord enlargement at the thoracolumbar junction was identified by myelography in each of two dogs, Exploratory laminectomy followed by durotomy and myelotomy permitted removal of an intramedullary neoplasm in each dog. In one animal the tumour was diagnosed to be an ependymoma, in the other the tumour had the characteristics of a nephroblastoma. Following surgery each dog recovered quickly to pre-operative status or better. In one dog there was long term resolution of neurological deficits, while the other was euthanased because of persistent faecal incontinence.     

Feline infectious peritonitis with spinal cord involvement in two cats.

Two cats from the same household had posterior paresis and hypergammaglobulinemia. Histologic evaluation of the spinal cords revealed a pyogranulomatous reaction consistent with that reported for feline infectious peritonitis.     

Developing a predictive model for spinal shock in dogs with spinal cord injury

BackgroundReduced pelvic limb reflexes in dogs with spinal cord injury typically suggests a lesion of the L4‐S3 spinal cord segments. However, pelvic limb reflexes might also be reduced in dogs with a T3‐L3 myelopathy and concurrent spinal shock.Hypothesis/ObjectivesWe hypothesized that statistical models could be used to identify clinical variables associated with spinal shock in dogs with spinal cord injuries.AnimalsCohort of 59 dogs with T3‐L3 myelopathies and spinal shock and 13 dogs with L4‐S3 myelopathies.MethodsData used for this study were prospectively entered by partner institutions into the International Canine Spinal Cord Injury observational registry between October 2016 and July 2019. Univariable logistic regression analyses were performed to assess the association between independent variables and the presence of spinal shock. Independent variables were selected for inclusion in a multivariable logistic regression model if they had a significant effect (P ≤ .1) on the odds of spinal shock in univariable logistic regression.ResultsThe final multivariable model included the natural log of weight (kg), the natural log of duration of clinical signs (hours), severity (paresis vs paraplegia), and pelvic limb tone (normal vs decreased/absent). The odds of spinal shock decreased with increasing weight (odds ratio [OR] = 0.28, P = .09; confidence interval [CI] 0.07‐1.2), increasing duration (OR = 0.44, P = .02; CI 0.21‐0.9), decreased pelvic limb tone (OR = 0.04, P = .003; CI 0.01‐0.36), and increased in the presence of paraplegia (OR = 7.87, P = .04; CI 1.1‐56.62).Conclusions and Clinical ImportanceA formula, as developed by the present study and after external validation, could be useful for assisting clinicians in determining the likelihood of spinal shock in various clinical scenarios and aid in diagnostic planning.     

Survival rates and outcomes in cats with thoracic and lumbar spinal cord injuries due to external trauma

Survival rates and outcome were retrospectively examined in 30 cats with traumatic spinal cord lesions to the thoracic and lumbar spine. Treatment included both surgical and non-surgical management. In cats with loss of deep pain sensation, a high incidence of myelomalacia was found during surgery or postmortem examination. The outcome in cats with grade II and III neurological dysfunction (11/18) was poor in two cases, functional in one and complete in eight. Recovery in cats with grade IV neurological dysfunctions (7/18) was poor in one case, functional in two and complete in four. The other 12 of the original 30 cats were euthanased within four days of presentation. The results of this study are compared with those reported in cats with spinal injuries due to spontaneous disc herniations and to those that have been achieved in cats with experimental transections of the spinal cord.