Cerebrospinal fluid studies in normal cows and cases of bovine spongiform encephalopathy

Survival associated with cerebrospinal fluid analysis in downer adult dairy cows: A retrospective study (2006-2014)

Background

Threshold values for total nucleated cell count (TNCC) and protein concentration in cerebrospinal fluid (CSF) of downer dairy cows suggestive of a spinal cord lesion were recently published.

Objectives

Determine short‐ and long‐term survival of downer cows that underwent CSF analysis using the reported threshold values. Evaluate the prognostic value of these threshold values to predict short‐ and long‐term survival.

Animals

Two hundred and fourteen downer adult dairy cows that underwent CSF analysis during hospitalization at the Centre Hospitalier Universitaire Vétérinaire (CHUV) of the Université de Montréal.

Methods

Retrospective study. Medical records of downer adult dairy cows presented to the hospital between January 2006 and October 2014 for which CSF analysis results were available were studied. Short‐term (discharge from hospital) and long‐term (completion of lactation) survival were determined and compared in accordance with CSF TNCC and protein concentration, using a Chi‐square test.

Results

Cows with CSF TNCC and/or protein concentration above the threshold values had a significantly lower short‐term survival rate (P = .02). The odds of nonsurvival of cows with one or both CSF values above the threshold values was 2.16 times higher than the odds for cows with values under the threshold values. CSF TNCC >4.5 cells/μL had sensitivity and specificity of 17.3% (95% CI: 10.7%‐25.7%) and 92.3% (95% CI: 85.4%‐96.6%), respectively, for predicting short‐term nonsurvival. CSF protein concentration >0.39 g/L had sensitivity and specificity of 20.9% (95% CI: 13.7%‐29.7%) and 91.4% (95% CI: 84.2%‐96.0%), respectively.

Conclusions

CSF analysis above threshold values used in this study is associated with increased odds of short‐term nonsurvival.

Bovine spongiform encephalopathy

Bovine spongiform encephalopathy is an infectious disease of cattle that is transmitted through the consumption of meat-and-bone meal from infected cattle. The etiologic agent is an aberrant isoform of the native cellular prion protein that is a normal component of neurologic tissue. There currently are no approved tests that can detect BSE in live cattle.

Cerebrospinal fluid findings in cattle with central nervous system disorders: a retrospective study of 102 cases (1990-2008)

BACKGROUND

Cerebrospinal fluid (CSF) analysis is routinely used to aid in the diagnosis of central nervous system (CNS) disease in animals. There is little comprehensive information available on the diagnostic utility of CSF analysis in cattle.

OBJECTIVES

The purpose of this retrospective study was to review the characteristic CSF findings of specific CNS diseases in cattle.

METHODS

Medical records of cattle in which CSF analysis had been performed between 1990 and 2008 were reviewed. Cattle were included in the study if they had a confirmed diagnosis of CNS disease (based on clinical signs, laboratory testing, and/or histopathologic results). Cattle were categorized as having infectious or noninfectious causes of CNS disease and subgrouped based on specific disease diagnosis. CSF results were summarized and compared using nonparametric statistical tests.

RESULTS

Data from 102 cattle, mostly female Holsteins, were included in the study. Bacterial infections, particularly listeriosis and neonatal meningitis, were the most common cause of CNS disease. Neonatal meningitis was characterized by a marked, predominantly neutrophilic, pleocytosis. Mild mononuclear pleocytosis was typical of listeriosis, but was also seen with abscesses, viral infections, salt poisoning, and trauma. Variable CSF results were seen in cattle with otitis-related meningitis and thromboembolic meningoencephalitis. CSF results were usually normal with toxic, metabolic, degenerative, and neoplastic disorders.

CONCLUSIONS

CSF analysis is a useful adjunctive test for the diagnosis of CNS diseases in cattle. When interpreted together with signalment and clinical signs, CSF results can assist clinicians in the antemortem diagnosis of specific bovine CNS disorders.

Cerebrospinal Fluid

This chapter discusses the anatomy, functions, and biochemistry of cerebrospinal fluid (CSF). CSF has four major functions: physical support of neural structures, excretion and “sink” action, intracerebral transport, and control of the chemical environment of the central nervous system. CSF provides a “water jacket” of physical support and buoyancy. The CSF is protective because its volume changes reciprocally with changes in the volume of intracranial contents, particularly blood. Thus, the CSF protects the brain from changes in arterial and central venous pressure associated with posture, respiration, and exertion. Acute or chronic pathological changes in intracranial contents can be accommodated, to a point, by changes in the CSF volume. The direct transfer of brain metabolites into the CSF provides excretory function. This capacity is important because the brain lacks a lymphatic system. The lymphatic function of the CSF is also manifested in the removal of large proteins and cells, such as bacteria or blood cells, by bulk CSF absorption. The “sink” action of the CSF arises from the restricted access of water-soluble substances to the CSF and the low concentration of these solutes in the CSF.

Diagnostic techniques and clinicopathologic findings in ruminant neurologic disease

In ruminant species, cerebrospinal fluid (CSF) collection and analysis provide rapid (in some situations, instant) information to the veterinary clinician investigating a disease problem in the living animal. CSF analysis is particularly useful with respect to confirming the presence of an inflammatory lesion involving the leptomeninges,such as bacterial meningoencephalitis, and in investigating potential compressive lesions of the spinal cord. When correctly performed under local anesthesia, lumbar CSF collection in ruminants is a safe procedure and there are no harmful sequelae. Familiarity with the technique aids high extradural injection of lidocaine or xylazine, which has many applications in farm practice. There are few indications for cisternal CSF collection in food animals.

The collection and analysis of cerebrospinal fluid as an aid to diagnosis in ruminant neurological disease

In ruminant species cerebrospinal fluid (CSF) collection and analysis provides rapid and, in some situations, instant information to the veterinary clinician investigating a disease problem in the living animal. CSF analysis is particularly useful with respect to confirming the presence of an inflammatory lesion involving the leptomeninges such as bacterial meningoencephalitis. When correctly performed under local anaesthesia, lumbosacral CSF collection in ruminants is a safe procedure and there are no harmful sequelae. There are few indications for cisternal CSF collection in food animal practice.

Cerebrospinal fluid composition of cattle with endotoxin-induced mastitis treated with isotonic (0.9%) or hypertonic (7.5%) sodium chloride

This study examined the safety of intravenous hypertonic saline in cattle with experimental gram-negative endotoxemia. Cerebrospinal fluid (CSF) composition was examined in five control cows and eight treated cows 24 hours after the intramammary infusion of 1 mg of endotoxin. Four of the endotoxin challenged cows were treated intravenously with isotonic (0.9%) sodium chloride and four cows were treated intravenously with hypertonic (7.5%) sodium chloride. Decreased CSF osmolality, and sodium and alpha globulin concentrations and increased CSF concentrations of beta globulin were observed in both endotoxin-challenged saline-treated groups. No CSF compositional differences were observed between endotoxin-challenged cows receiving isotonic or hypertonic saline. Although no cytologic or biochemical evidence of salt poisoning was observed in cows receiving hypertonic saline, significant changes were observed in the CSF composition of both endotoxin-infused saline-treated groups.

Analysis of cerebrospinal fluid from field cases of some common ovine neurological diseases

Analysis of cerebrospinal fluid (CSF) samples from normal sheep and from cases of some common neurological diseases revealed a significant increase (P less than 0.05) in the group mean CSF protein concentration for meningitis, listeriosis and spinal abscess but not for scrapie, spinal injury, ovine pregnancy toxaemia or polioencephalomalacia. The CSF white blood cell count (WBC) was significantly increased (P less than 0.05) in the meningitis group and in those cases of listeriosis which failed to respond to antibiotic therapy. All cases of bacterial infection of the central nervous system (CNS) could be identified by the combined interpretation of the protein concentration and the differential WBC count. It is concluded that CSF analysis is useful clinically in differentiating traumatic from infective spinal lesions and toxic or metabolic lesions from bacterial meningitis in sheep.

Bovine spongiform encephalopathy (BSE): the current situation and research

Bovine spongiform encephalopathy (BSE), discovered in Great Britain in 1986, was to pose one of the most serious threats to the well-being of the British cattle industry this century. The disease is now established as a member of the group of diseases known as the sub-acute spongiform encephalopathies caused by unconventional, transmissible agents and which includes scrapie of sheep. It is from scrapie of sheep that it appears BSE has resulted though it is possible BSE may have existed in a sub-clinical form in cattle. The vehicle of transmission is meat and bone meal prepared from infected ruminant carcases and included in the protein concentrate rations of cattle, especially dairy cattle in which the disease predominates. Most animals become exposed as calves and the incubation period is typically 4-5 years with most cases occurring at this age. The increase in exposure of cattle to infection that resulted in disease in 1985/1986 was 1981/1982. The factors that contributed to this increase were an increasing sheep population, possibly an increase in the prevalence of scrapie and changes in the industrial processing of animal waste to prepare meat and bone meal. The clinical signs of BSE include abnormal behaviour, posture, gait and an increased sensitivity to visual and aural stimuli. There is loss of condition and milk yield. In only one of 28,197 cases of BSE confirmed by 10 May 1991 can feed be almost certainly ruled out as a source of infection. This therefore may be a singleton case of maternal transmission though we cannot be certain. Every other case so far has been exposed to meat and bone meal in the diet and thus resulted in an extended common source epidemic. A large research programme is underway to investigate the epidemiology, clinicopathology, transmission and molecular biological/genetic aspects of the disease. Much is collaborative between Institutes and Member States of the European Community, in which the disease, as in Britain, is notifiable. In Britain the lynch pin of control for animal health has been the ban established in July 1988 on feeling of ruminant protein to ruminant animals. Though there is no evidence that either BSE or scrapie is a hazard to humans, as a precautionary measure, suspect animals are compulsorily slaughtered and destroyed (except all brains are taken for diagnosis) with compensation being paid at 100% of value. Milk from such animals is also destroyed.(ABSTRACT TRUNCATED AT 400 WORDS)