Tiny reviews – JVIM Nov/Dec 2017

by Deena Tiches, DVM, DACVIM (Neurology)
Originally posted 2018-03-15 on the NeuroWebVet website; modified and reprinted with permission.

This edition of tiny neuro reviews covers neurology articles published in the Nov/Dec 2017 issue of Journal of Veterinary Internal Medicine


CM/SM & cranial cervical junction abnormalities

Researchers and veterinarians at the Veterinary Teaching Hospital of University of Helsinki described Chiari-like malformation (CM), syringomyelia (SM), and cranial cervical junction (CCJ) abnormalities in Chihuahuas. Fifty-three client-owned Chihuahuas were examined prospectively. Scratching was the most common CM/SM-related clinical sign (73%) and decreased postural reaction the most common neurologic deficit (87%). CM (100%) and SM (38%) was detected in these dogs. Syringomyelia was associated with the presence of CM/SM-related clinical signs (P = 0.034), and medullary kinking and sum indices were higher in dogs with clinical signs (P = 0.016 and P = 0.007, respectively). They concluded that syringomyelia and CCJ abnormalities are prevalent in Chihuahuas. Syringomyelia was an important factor for the presence of CM/SM-related clinical signs, but many dogs suffered from similar clinical signs without being affected by SM, highlighting the clinical importance of CCJ abnormalities in Chihuahuas. Download article

Progressive myelomalacia in IVDE

The onset and progression of clinical signs of progressive myelomalacia (PMM) in a large case cohort of dogs were completed at North Carolina State University College of Veterinary Medicine. Fifty-one dogs with either a histopathologic diagnosis or high clinical suspicion of PMM due to intervertebral disk extrusion were selected by a medical records search. Approximately half of the dogs were dachshunds. A total of 56 disc extrusions were reported (5 dogs had 2 sites involved). Around 20% of the disk extrusions were located at T12-T13 and 33% were mid-to-caudal lumbar discs (between L3 and L6). More than half of the dogs (30 of 51) had systemic abnormalities documented. These included hypothermia (ie, rectal temperature lower than 99°F) in 29% of the dogs, fever (ie, rectal temperature higher than 102.5°F) in 14%, and diffuse hyperesthesia (ie, not localized to the spine) in 18%. The majority of dogs developed PMM within 2 days of presentation and was euthanized within the next 3 days. However, onset can be delayed up to 5 days after presentation and progression to euthanasia taking as long as 2 weeks. Mid-to-caudal lumbar discs might be associated with an increased risk of PMM. Download article

Bacteriuria in chronically paralyzed dogs

Paralysis is a known risk factor for urinary tract infections (UTI), sepsis, and death in paralyzed people, but there are no data available on diagnostic criteria for UTI versus bacteriuria, their frequency, or clinical implications in chronically paralyzed dogs. A retrospective, observational study was conducted at the College of Veterinary Medicine, North Carolina State University to determine the frequency of bacteriuria, associated clinical signs, and survival rate in chronically paralyzed dogs. Medical records of dogs meeting inclusion criteria were reviewed for results of urine culture (UC), urinalysis, and clinical signs. Outcome was compared between dogs with and without bacteriuria. Thirty-five of 47 dogs had at least 1 positive UC, and 13 had recurrent bacteriuria. Fever was present at time of UC in 5 of 68 observations, 2 with and 3 without bacteriuria. Pyuria was significantly associated with positive cultures (P < 0.001), but cloudiness was not (P = 0.076). Survival data in 35 dogs (8 dead) showed no association between bacteriuria and survival (P = 0.69). Bacteriuria is common in paralyzed dogs but does not cause fever, therefore the diagnostic criteria of UTI are unclear. They did not detect an association of bacteriuria with survival, but this needs further confirmation. Download article

Phenobarbital-induced pseudolymphoma

Canada West Veterinary Specialists submitted a case report of suspected phenobarbital-induced pseudolymphoma in a dog. Pseudolymphoma is a drug reaction to anticonvulsant medications that is well recognized in humans. Until now, it has been reported in one cat but no dogs. In this report, lymphoma-like clinical signs were suspected to be secondary to phenobarbital administration in a dog. A 2.5-year-old male, neutered shepherd mix presented with a 3-day history of progressive ataxia, dazed mentation, pyrexia, and lethargy. The dog developed generalized lymphadenopathy and sustained pyrexia during hospitalization. Current medications were levetiracetam and phenobarbital for epilepsy. Serum concentrations of both were within standard therapeutic ranges. Abdominal ultrasound revealed hepatomegaly, splenomegaly, and generalized lymphadenopathy. Cytology of the peripheral lymph nodes was consistent with reactive lymph nodes, and aspirates of the liver and spleen revealed histiocytic-neutrophilic inflammation. Phenobarbital was discontinued and replaced with zonisamide. Within 24 hours, the dog was normothermic, and other clinical signs resolved within a week. This case highlights a potentially serious, yet reversible, adverse reaction to phenobarbital in a dog. This idiosyncratic reaction could be mistaken for neoplasia and is an important differential for lymphoma-like signs in any dog administered phenobarbital. Download article