The Central Nervous System

Prospective randomized trial comparing relapse rates in dogs with steroid-responsive meningitis-arteritis treated with a 6-week or 6-month prednisolone protocol

BACKGROUND

Traditionally, 6-month courses of prednisolone are used to treat steroid-responsive meningitis-arteritis (SRMA), but this medication is associated with adverse effects that can lead to poor quality of life.

HYPOTHESIS/OBJECTIVES

Resolution of clinical signs and rate of relapse of SRMA would not be significantly different between a 6-month prednisolone protocol and a 6-week protocol.

ANIMALS

Forty-four hospital cases from multiple referral centers in the United Kingdom (2015-2019). Twenty of 44 were treated with the 6-month protocol and 24/44 with the 6-week protocol.

METHODS

Prospective, randomized trial with 12-month follow-up. The same prednisolone protocol reinitiated in the event of relapse. Analysis of relapses with binary logistic and Poisson regression modeling.

RESULTS

All cases responded to their treatment protocol. Relapses occurred in 6/20 (30%) of the 6-month protocol and 9/24 (38%) of the 6-week protocol. There was no statistical difference in the incidence risk of at least 1 relapse between the 2 groups (odds ratio = 1.40; 95% confidence interval [CI], 0.40-4.96, P = 0.60). Among the 15 dogs that relapsed, 10/15 (67%) relapsed once, 3/15 (20%) relapsed twice, and 2/15 (13%) relapsed 3 times. No statistical difference was detected in the incidence rate ratio (IRR) of total relapse events between the 2 groups (IRR = 1.46; 95% CI, 0.61-3.48; P = 0.40).

CONCLUSIONS AND CLINICAL IMPORTANCE

"Short" 6-week prednisolone protocols could be used to treat SRMA, thereby presumably reducing the duration and severity of prednisolone's adverse effects.

Case Report: Cytologic Description of Somatotroph Pituitary Adenoma in a Cat

This case report describes for the first time the cytologic characteristics of a hormonally secreting pituitary adenoma in a cat. An 8-year-old female spayed domestic long-haired cat was referred with a previous diagnosis of hypersomatotropism and secondary diabetes mellitus 7 months prior. Clinical signs included weight loss, polyphagia, polyuria, and polydipsia. Serum insulin-like growth factor-1 was 340 nmol/L (RI: 12-92), and CT scan revealed a hypophyseal mass, and a presumptive diagnosis of acromegaly was made. A transsphenoidal hypophysectomy was performed. A fragment of the pituitary gland was subjected to a squash preparation and cytology revealed a neuroendocrine neoplasm characterized by anisokaryosis and prominent nucleoli. Additional cytologic findings included cell cohesiveness, indistinct cytoplasmic borders, nuclear crowding, molding, and fragmentation. A diagnosis of adenoma was based on a lack of histopathologic or imaging evidence of invasion. A week later, during post-surgical hospitalization, the patient worsened and died. Histopathology from a necropsy procedure revealed fibrinosuppurative meningitis as a post-surgical complication. Pituitary adenomas might have an aggressive cytologic appearance, despite a lack of histopathologic invasion or dissemination.

Cerebrospinal fluid analysis in dogs: Main patterns and prevalence of albuminocytological dissociation

BACKGROUND

Albuminocytological dissociation (ACD) of the cerebrospinal fluid (CSF) is defined as an increased total protein concentration with normal total nucleated cell count. It is suspected to occur in diseases that alter the blood-brain barrier, increase the production of protein or obstruct the flow of CSF. The purposes of this study were to review the CSF analysis results of a large cohort of dogs with neurological conditions, to analyse the total prevalence of ACD and to describe which diseases have a higher prevalence of ACD.

STUDY DESIGN AND METHODS

Medical records were retrospectively searched for dogs whom CSF was sampled from 2012-2019. Data collected included signalment, body weight, site of collection of the CSF, CSF analysis results, and final diagnosis.

RESULTS

A total of 497 dogs met the inclusion criteria. ACD was identified in 16.5% (82/497) of dogs. The diseases with higher proportion of ACD were cranial nerve neuropathy (6/10; 60.0%), brain tumour (10/24; 41.7%), idiopathic vestibular disease (7/17; 41.2%) and brain vascular disease (4/13; 30.8%).

CLINICAL SIGNIFICANCE

This study describes the CSF patterns of the most common neurological conditions in dogs, also characterizing, for the first time in dogs, the prevalence and causes of ACD, which was identified in 16.5% of the samples. The diseases with highest proportions of ACD were cranial nerve neuropathy, brain tumour, idiopathic vestibular disease and brain vascular disease.

Rapid in-house method of CSF analysis utilising sedimentation direct from the spinal needle

OBJECTIVES

To establish the utility of a novel in-house method of CSF analysis using sedimentation cytology direct from the spinal needle for the detection of laboratory-defined pleocytosis.

MATERIALS AND METHODS

In dogs and cats undergoing routine CSF analysis for investigation of neurological signs, an additional preparation was made at the patient's side by inverting the spinal needle on a slide and sedimenting for at least 1 hour. Nucleated cellularity and differential counts were assessed and compared with "gold-standard" analysis. Variability of cell counts between observers and within slides using the new method was evaluated to optimise the procedure.

RESULTS

Using a ×50 objective, at least 10 fields and an average of more than five cells per field were considered appropriate guidelines to achieve correct classification of samples (normal or pleocytosis). The new method had high sensitivity (89%) and specificity (100%) for the detection of laboratory-defined pleocytosis. Agreement on the type of pleocytosis was good.

CLINICAL SIGNIFICANCE

Clinically useful information can be obtained from CSF samples in a patient-side setting without additional equipment. This technique may be of benefit if little fluid is available or if logistical constraints limit the availability of rapid specialist results.

Ganglion Cytology: A Novel Rapid Method for the Diagnosis of Equine Dysautonomia

Equine dysautonomia (grass sickness) is characterized by autonomic neuronal degeneration and is often fatal. As outbreaks occur, rapid diagnosis is essential but confirmation currently requires histological examination. This study evaluated diagnostic accuracy of cytological examination of cranial cervical ganglion (CCG) scrapings for dysautonomia diagnosis. CCG smears from 20 controls and 16 dysautonomia cases were stained with May-Grünwald Giemsa (MGG), hematoxylin and eosin (HE), and cresyl fast violet (CFV), with HE-stained histological sections of CCG as gold standard for diagnosis. Examining all 3 stains together, the sensitivity and specificity were 100%. Occasional individual smears (4/107, 3.7%) were nondiagnostic due to low cellularity, and in a few individual smears the final diagnosis was correct but more tentative (CFV: 5/33 [15.1%], HE: 2/34 [5.9%], and MGG: 4/36 [11.1%]), due to low cellularity or suboptimal cell morphology. CCG cytology was considered reliable for rapid postmortem diagnosis of equine dysautonomia, particularly using MGG.