ABSTRACT. A 3-month-old male Japanese cat with feline parvovirus infection, showing central and cervical nerve abnormalities, was diagnosed as hydrocephalus and syringomyelia by use of magnetic resonance imaging (MRI). The cat was maintained clinically by medical treatment even though he could not stand. The MRI scans obtained about 5 months later showed that the ventricles had increased in size and the cervical syrinx had extended into the thoracic spinal cord. Ventriculoperitoneal (VP) shunt was performed. One week after surgery, neurological conditions had improved. At the postoperative MR images, the ventricles had decreased in size and the syrinx in the cervical and thoracic spinal cord could no longer be seen. The cat was still alive and was able to walk well. KEY WORDS: feline, magnetic resonance imaging, syringomyelia.J. Vet. Med. Sci. 63(12): 1331-1334, 2001 Hydrocephalus is a term commonly used to describe a condition involving abnormal dilatation of the ventricular system within the cranium [11,15]. Viral infections such as feline infectious peritonitis (FIP) are a common cause of hydrocephalus in cats [15,18]. Syringomyelia has been defined as fluid-filled cavities in the substance of the spinal cord, with destruction of the nervous tissue [19]. Its cause is unknown, but it may be associated with or result from hydrocephalus [16,24]. Ventriculoperitoneal (VP) shunts are commonly used to divert the flow of cerebrospinal fluid (CSF) from the ventricles of the brain to the peritoneal cavity in human neurosurgery [11], and have proved to be an effective surgical treatment for hydrocephalus in dogs [15] and cats [23]. Several investigators [12,15,16,24] in the veterinary field have suggested magnetic resonance imaging (MRI) to be a useful technique for the antemortem diagnosis of several cranial and spinal disorders in animals. This article describes the clinical findings in, and management of, a cat with hydrocephalus and syringomyelia, together with temporal changes in MR images obtained before and after the insertion of a VP shunt.A 3-month-old male Japanese cat was referred because of severe ataxia following an inadvertent fall onto the floor from a height of about 2 m. The cat had not been vaccinated against any diseases. The owner stated that the cat had walked well until the event. Laboratory examination revealed neutrophilia (56,400/µl; Segmented neutrophils 99%, Lymphocytes 1%). Physical examination revealed severe muscular atrophy over the whole body and myotonus of all four limbs. Neurological examination revealed several cranial nerve abnormalities such as torticollis to the right, nystagmus and depression, and cervical nerve abnormalities such as clasp-knife rigidity of fore limbs. The menace response was absent, but the papillary light reflex and the palpebral reflex were normal. Asymmetry of the pupils was also observed. Patellar reflexes were exaggerated and flexor reflexes were detected in all four limbs. Elevated rectal temperatures (40.8, 40.6 and 39.6°C) were noted on days 7, 8 and 9, ...

This study was designed to characterize the effect of medetomidine (Med) on canine electroencephalography (EEG), to evaluate the use of quantitative EEG for assessing sedation levels and to explore the correlation between the serum concentration of Med and the quantitative EEG. Four groups of dogs were given Med at doses of 20, 40, 80 and 160 microg/kg (Med-20, Med-40, Med-80 and Med-160 groups). Following Med administration, there was synchrony between each unipolar EEG lead. On EEG power spectrum analysis of the bipolar leads, all groups showed a significant depression of the 14-30 Hz components. The power of the 1-3 Hz component in the Med-80 and Med-160 groups was significantly increased, although there were few changes in the other groups. Similar results were obtained from raw data analysis. As a result of quantitative EEG analysis, spectrum edge frequency 90 analysis (SEP90) showed that the frequency was significantly reduced in all groups after Med administration. A dose-response effect was observed in all groups except for the Med-160 group. Both of these EEG analyses were significantly correlated with the serum concentration of Med. However, the result of the SPF90 analysis sugested a stronger correlation than that for median edge frequency analysis. In conclusion, care must be taken in veterinary clinical diagnoses when Med is used during EEG recording, as Med may cause increased activity in the low frequency band and a decrease in high frequency band activity. In addition, quantitative EEG analysis may be useful in assessing the depth of sedation and in further studies on Med administration.

This report describes the use of magnetic resonance imaging (MRI) in five dogs to diagnose spontaneous syringomyelia. Four of the dogs had cervical syringomyelia associated with hydrocephalus, and one of these cases was analogous to the Dandy‐Walker syndrome in humans. The fifth dog had thoracic syringomyelia without hydrocephalus. It was possible to diagnose the condition antemortem in all of the dogs by MRI. It is suggested that MRI is a straightforward and effective tool for the antemortem diagnosis of syringomyelia in dogs.

We investigated the way in which Na+ channel blocking class I antiarrhythmic drugs, lidocaine (30 mu M), flecainide (30 mu M), and RS-2135 (100 mu M) affected contractions elicited by several protocols in rat and rabbit ventricular strips. Rabbit ventricles showed a positive force-frequency relation, and antiarrhythmic drugs inhibited the contraction, flattening the force-frequency curve. In contrast, rat ventricles showed a negative force-frequency relation, and the drugs shifted the force-frequency curve downward. Rapid-cooling contracture (RCC) also showed a positive or negative dependence on the frequency of preceding stimulation in rabbit or rat ventricles, respectively. All drugs inhibited the RCC, suggesting that they reduced the Ca2+ content in the sarcoplasmic reticulum. Ryanodine (1 mu M) abolished the RCC in both muscles and the contraction in rat muscles, but partially decreased contractions at high frequencies in rabbit ventricles. Antiarrhythmic drugs caused a further inhibition of contractions in the presence of ryanodine in rabbit ventricles. These results indicate that inhibition of Na+ channels by antiarrhythmic drugs alters Na+ -Ca2+ exchange, resulting in a decrease in the Ca2+ content in the sarcoplasmic reticulum (SR) and the Ca2+ entry through the exchanger.

ABSTRACT. Three dogs were evaluated in our study using magnetic resonance imaging (MRI) to reveal the anatomical deformity and the degree of the lesion of cauda equina. In all dogs, MRI revealed soft tissue, such as cauda equina, epidural fat, and intervertebral disc, at the lumbosacral region clearly without contrast medium. Our results suggest that MRI has some advantages in evaluating cauda equina syndrome in dogs. -KEY WORDS: canine, cauda equina syndrome, magnetic resonance imaging (MRI).J. Vet. Med. Sci. 60(12): 1345-1348, 1998 side of the L7-S1 disc space was appeared to encapsulate. The sagittal T2-weighted image (Fig. 1b) showed that the cauda equina at the lesion of L7-S1 was strongly compressed and the L7-S1 intervertebral disc was hypointense. We diagnosed this dog as discospondylitis which caused by B. canis at L7-S1 intervertebral disc space. Dog 2: This dog had a decreased tail tone, weakness of the hind limbs and excreted soft feces. Survey radiographs revealed that the ventral canal height was decreased at the level of L7-S1 lesion and the density of both L7 caudal and S1 cranial end-plates were increased (Fig. 2a). The sagittal T1-weighted image ( Fig. 2b) showed that the loss of epidural fat and the L7-S1 intervertebral disc was hypointense. The cauda equina was compressed and elevated at the level of sacral region. We diagnosed this dog as lumbosacral stenosis at L7-S1 lesion.Dog 3: The clinical sign in this dog was decreased tail tone and weakness of the hind limbs, especially left side. The sagittal T1-weighted image (Fig. 3) showed that L7 vertebral body was destroyed and the L7-S1 intervertebral disc was hypointense and the osteophyte at ventral side of the L7 vertebral body was slightly hypointense. We diagnosed that the cauda equina was compressed by means of the destroyed L7 vertebral body and osteophyte.Hathcock et al. [3] showed that it was difficult to diagnose the cauda equina syndrome, because survey radiography or myelography has not been able to reveal the cauda equina lesion. In epidulography or discography [11], the result was sometimes false as the contrast medium leaked to arachinoid space and after examination, some animals rarely showed back pain. The advantage of MRI was that it was able to show, without the use of contrast medium, the * CORRESPONDENCE TO: TAURA, Y., Department of Veterinary Hospital, Faculty of Agriculture, Yamaguchi University, 1677-1 Ooaza Yoshida, Yamaguchi 753-8515, Japan. Cauda equina syndrome causes compression, displacement, and disorder of nerve roots in lumbosacral region [6,10,12]. Until now several examinations are used to confirm a diagnosis of cauda equina syndrome [1-4, 6, 11]. However, it is difficult to make a definite diagnosis. Recently, MRI as a diagnosic tool has come into wide use in veterinary practice [5,[7][8][9]13]. Because of high resolution of MRI, it is possible to get clear images of cauda equina [2,4]. The purpose of present study was to survey anatomical change of cauda equina lesion in three dogs of different breeds and t...