Joane M. Parent

Outcome of medical and surgical treatment in dogs with cervical spondylomyelopathy : 104 cases (1988-2004)

OBJECTIVE To compare outcomes and survival times for dogs with cervical spondylomyelopathy (CSM; wobbler syndrome) treated medically or surgically. DESIGN Retrospective case series. ANIMALS 104 dogs. PROCEDURES Medical records of dogs were included if the diagnosis of CSM had been made on the basis of results of diagnostic imaging and follow-up information (minimum, 6 months) was available. Ordinal logistic regression was used to compare outcomes and the product-limit method was used to compare survival times between dogs treated surgically and dogs treated medically. RESULTS 37 dogs were treated surgically, and 67 were treated medically. Owners reported that 30 (81%) dogs treated surgically were improved, 1 (3%) was unchanged, and 6 (16%) were worse and that 36 (54%) dogs treated medically were improved, 18 (27%) were unchanged, and 13 (19%) were worse. Outcome was not significantly different between groups. Information on survival time was available for 33 dogs treated surgically and 43 dogs treated medically. Forty of the 76 (53%) dogs were euthanized because of CSM. Median and mean survival times were 36 and 48 months, respectively, for dogs treated medically and 36 and 46.5 months, respectively, for dogs treated surgically. Survival times did not differ significantly between groups. CONCLUSIONS AND CLINICAL RELEVANCE In the present study, neither outcome nor survival time was significantly different between dogs with CSM treated medically and dogs treated surgically, suggesting that medical treatment is a viable and valuable option for management of dogs with CSM.

Incidence of and risk factors for seizures after myelography performed with iohexol in dogs: 503 cases (2002-2004)

OBJECTIVE To establish the incidence of and risk factors for seizures following myelography performed with iohexol in dogs. DESIGN Retrospective case series. ANIMALS 503 dogs. PROCEDURES Medical records were searched for dogs that underwent myelography between April 2002 and December 2004. Data extracted included body weight, breed, age, sex, volume and dose of iohexol, site of injections, location of lesion, duration of anesthesia, surgical procedures immediately after myelography, use of acepromazine, and presence or absence of seizures. RESULTS 15 (3%) dogs had postmyelographic seizures. Risk factors significantly associated with seizures were size of dogs (large dogs were 35.35 times as likely to have seizures as were small dogs), location of contrast medium injection (dogs in which iohexol was injected into the cerebellomedullary cistern were 7.4 times as likely to have seizures as were dogs in which iohexol was injected into the lumbar cistern), location of lesion (dogs with lesions at the level of the cervical portion of the vertebral column were 4.65 times as likely to develop seizures as were dogs with lesions in other regions), and total volume of iohexol. Mean ± SD total volume of iohexol was 11.73 ± 5.52 mL (median, 10.5 mL [range, 3.0 to 21.0 mL]) for dogs that had seizures and 4.57 ± 4.13 mL (median, 3.5 mL [range, 0.75 to 45.0 mL]) for those that did not. CONCLUSIONS AND CLINICAL RELEVANCE Large-breed dogs with cervical lesions and large volumes of iohexol injected into the cerebellomedullary cistern had the highest risk of seizures. The use of contrast medium volumes > 8 mL in large dogs should be avoided, with preference given to injections into the lumbar cistern.

Clinical and MRI Findings in Three Dogs with Polycystic Meningiomas

One spayed female Labrador retriever and two castrated male golden retrievers were evaluated for chronic (i.e., ranging from 3 wk to 24 wk) neurologic signs localizable to the prosencephalon. Signs included seizures, circling, and behavior changes. MRI demonstrated extra-axial, contrast-enhancing, multiloculated, fluid-filled, cyst-like lesions with a mass effect, causing compression and displacement of brain parenchyma. Differential diagnoses included cystic neoplasm, abscess or other infectious cyst (e.g., alveolar hydatid cyst), or fluid-filled anomaly (e.g., arachnoid cyst). The cyst-like lesions were attached to the rostral falx cerebri in all cases. In addition, case 2 had a second polycystic mass at the caudal diencephalon. Surgical biopsy (case 3 with a single, rostral tumor via transfrontal craniectomy) and postmortem histology (in cases 1 and 2) confirmed polycystic meningiomas. Tumor types were transitional (cases 1 and 3) and fibrous (case 2), with positive immunohistochemical staining for vimentin. Case 3 was also positive for E-cadherin, s100, and CD34. In all cases, staining was predominantly negative for glial fibrillary acid protein and pancytokeratins, supporting a diagnosis of meningioma. This report describes the first cases of polycystic meningiomas in dogs. Polycystic meningiomas are a rare, but important, addition to the differential diagnoses for intracranial cyst-like lesions, significantly affecting planning for surgical resection and other therapeutic interventions.

Investigation of the use of three electroencephalographic electrodes for long-term electroencephalographic recording in awake and sedated dogs

OBJECTIVE To compare electroencephalography (EEG) artifact associated with use of the subdermal wire electrode (SWE), gold cup electrode (GCE), and subdermal needle electrode (SNE) over an 8-hour period in sedated and awake dogs. ANIMALS 6 healthy dogs. PROCEDURES 8 EEG channels were recorded during 20-minute video-EEG recording sessions (intermittently at 0.5, 2, 4, 6, and 8 hours) with and without chlorpromazine sedation. Nonphysiologic artifacts were identified. Duration of artifact was summed for each channel. Number of unaffected channels (NUC) was determined. RESULTS NUC was significantly affected by electrode type and sedation over time; median for SWE (2.80 channels; 95% confidence interval [CI], 0.84 to 5.70 channels) was significantly different from medians for GCE (7.87 channels; 95% CI, 7.44 to 7.94 channels) and SNE (7.60 channels; 95% CI, 6.61 to 7.89 channels). After 4 hours, NUC decreased in awake dogs, regardless of electrode type. In awake dogs, duration of artifact differed significantly between SWE and GCE or SNE; medians at 8 hours were 61.55 seconds (95% CI, 21.81 to 173.65 seconds), 1.33 seconds (95% CI, 0.47 to 3.75 seconds), and 21.01 seconds (95% CI, 6.85 to 64.42 seconds), respectively. CONCLUSIONS AND CLINICAL RELEVANCE The SWE had a significant duration of artifact during recording periods > 2 hours, compared with results for the GCE and SNE, in awake dogs. The GCE, SNE, and sedation resulted in significantly more channels unaffected by artifact. For longer recordings, caution should be exercised in selecting EEG electrodes and sedation state, although differences among electrodes may not be clinically relevant.