Neurological diseases of rottweilers: Neuroaxonal dystrophy and leukoenceph- alomalacia

Neuroaxonal dystrophy (NAD) and leukoencephalomalacia (LEM) are two neurological disorders of the rottweiler that initially present as ataxia of all four limbs. Disorders to be included in the differential diagnosis are caudal cervical spondylomyelopathy, canine distemper virus meningoencephalomyelitis, other nervous system infections or inflammations and spinal cord neoplasia. All diagnostic tests including myelography, cerebrospinal fluid analysis, electrodiagnos-tic testing and serum and cerebrospinal fluid titres for canine distemper virus are normal in NAD and LEM. There is no treatment for either disease and neurological signs progressively deteriorate. Eventually neurological deficits develop besides ataxia and these help differentiate NAD from LEM. Dogs with NAD develop head tremors and nystagmus while dogs with LEM develop conscious proprioceptive deficits and quadriparesis; the short term prognosis for NAD is better than LEM. Most dogs with LEM are euthanased because of non-ambulatory tetraparesis within one year. The histopathological lesions associated with NAD include axonal spheroids in many spinal cord and caudal brainstem nuclei and reduced numbers of Purkinje cells in the cerebellum, while in LEM, multifocal areas of demyelination and malacia of the spinal cord and brainstem are the primary histopathological lesions. Both NAD and LEM are suspected to have an autosomal recessive genetic transmission.     

Granulomatous meningoence-phalomyelitis in 21 dogs

Granulomatous meningoencephalomyelitis (GME) is a well recognised disease entity affecting dogs. It manifests in a wide variety of clinical syndromes. The lesion is characterised by focal or disseminated non-caseating granulomas in the brain and spinal cord, non-suppurative meningitis and marked perivascular lymphoid cuffing. The clinical signs can be acute and rapidly progressive or can manifest as a chronic relapsing disease. In this survey, 12 clinical cases were referred to Murdoch University Veterinary Hospital and nine cases were submitted for necropsy. While cerebrospinal fluid examination in seven of these cases suggested inflammatory disease, necropsy confirmed the presence of GME. An immunohistochemical technique for detection of distemper virus antigen failed to identify the presence of distemper virus antigen in any of the cases. It was concluded that distemper virus was not involved in the aetiology of these 21 cases all of which were confirmed by post mortem examination.     

Antemortem Diagnosis of CDV Infection by RT-PCR in Distemper Dogs with Neurological Deficits without the Typical Clinical Presentation

In dogs with neurological disturbances without myoclonus and extraneural signs, the clinical diagnosis of distemper is difficult perform. Considering the great infectious potential of the disease, the possibility of carrying out an antemortem diagnosis of distemper is important, particularly in hospitalized patients with neurological disease. The present study was carried out to evaluate RT-PCR for antemortem CDV detection in hospitalized dogs with neurological disturbances without the typical findings of distemper. We investigated five dogs with canine distemper virus (CDV) encephalomyelitis, in which the clinical diagnosis was not performed owing to the absence of characteristic signs of the disease, such as myoclonus and systemic signs. We observed an apparent high sensitivity of RT-PCR in urine samples for detection of CDV: four out of five urine samples were RT-PCR positive. The results of the present study suggest that urine is a good biological sample for antemortem CDV detection by RT-PCR in dogs with distemper encephalomyelitis in which the clinical diagnosis is likely to be difficult owing to the absence of suggestive distemper signs. The use of two different body fluids (urine and CSF) may increase the RT-PCR sensitivity for antemortem diagnosis of distemper in such cases.     

Cerebrospinal Fluid PCR and Antibody Concentrations against Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato in Dogs with Neurological Signs

Background: The tick-borne bacteria Borrelia burgdorferi sensu lato (sl) and Anaplasma phagocytophilum have been suspected to cause neurological signs in dogs. Diagnosis often has been made based on positive antibody titers in serum of dogs with neurological signs, but a high seroprevalence in dogs in at-risk populations makes diagnosis difficult.
Objective: To determine if the neurological signs in dogs examined were caused by any of these bacteria.
Animals: Fifty-four dogs presented to a board-certified neurologist.
Methods: Prospective study. We divided dogs into 2 groups: those with inflammatory diseases of the central nervous system (CNS) and those with neurological signs from other diseases. Blood and cerebrospinal fluid (CSF) from all dogs were analyzed.
Results: Dogs with inflammatory CNS diseases showed no serum antibodies against any of the agents. Among dogs with neurological signs from other diseases, 10.3% had serum antibodies for B. burgdorferi sl and 20.5% for A. phagocytophilum . All blood samples analyzed for bacterial deoxyribonucleic acid (DNA) and all CSF analyzed for antibodies and bacterial DNA for the 2 agents were negative.
Conclusions and Clinical Importance: Based on this study, these bacteria are unlikely causes of neurologic disease in dogs and the presence of serum antibodies alone does not document or establish a definitive diagnosis of CNS disease caused by these organisms. Dogs that have neurologic disease and corresponding serum antibodies against these agents should have additional tests performed to assess for other potential etiologies of the signs.     

Diagnosis of Inflammatory and Infectious Diseases of the Central Nervous System in Dogs: A Retrospective Study

The medical records of 220 dogs with inflammatory/infectious diseases of the central nervous system (CNS) were retrospectively examined. The aims of the study were to determine if clinical and clinicopathologic data (not including biopsy or necropsy examination) could distinguish inflammatory CNS diseases from diseases of other types, and to search for criteria allowing differentiation of specific inflammatory diseases. The signalment, historical findings, extraneural and neurological signs, and the lesion site contributed marginally to a specific diagnosis. Multifocal signs were only noticed in one third of the dogs with inflammatory/infectious diseases. Particular neurological abnormalities were more frequent in certain diseases than in others (eg, myoclonus was frequent in dogs with distemper, but it was also found in those with other meningoencephalomyelitides). Hematologic findings contributed to the diagnosis in certain conditions (eg, canine distemper encephalitis, protozoal encephalomyelitis, steroid-responsive meningitis-arteritis). Cerebrospinal fluid examinations, including immunoglobulin G index and cytology were useful to separate meningoencephalomyelitides from the other CNS diseases and to distinguish certain conditions from others. In most cases a specific diagnosis depended on a combination of clinical signs and ancillary diagnostic aids. Still, a specific diagnosis remained very difficult, if not impossible, in at least one third of the dogs.     

Fungal infections of the central nervous system in the dog and cat

Fungal infections of the central nervous system (CNS) in dogs and cats are uncommon. The purpose of this paper is to review the clinical signs, diagnostic tests, and therapeutic options of fungal infections of the CNS in the dog and cat. Clinical signs are dependent on lesion location and are often multifocal. Extraneural involvement is common. Antemortem diagnosis can be difficult and is definitively made via cytology, biopsy, or culture of an affected organ or cerebrospinal fluid (CSF). Magnetic resonance imaging can support a diagnosis and may assist in therapeutic decisions. Fungal serology can support a diagnosis when direct visualization of the organism is not possible. Long-term azole maintenance therapy is suggested to enhance survival and prevent relapse. Serial cerebrospinal fluid evaluation and magnetic resonance imaging may identify early relapse.     

Uncommon acute neurologic presentation of canine distemper in 4 adult dogs

Four uncommon cases of canine distemper (CD) were diagnosed in vaccinated adult dogs. All dogs had acute onset of neurologic signs, including seizures, abnormal mentation, ataxia, and proprioceptive deficits. Polymerase chain reaction for CD virus was positive on cerebrospinal fluid in 2 cases. Due to rapid deterioration the dogs were euthanized and CD was confirmed by postmortem examination.     

Combined cytosine arabinoside and prednisone therapy for meningoencephalitis of unknown aetiology in 10 dogs

OBJECTIVES: The differential diagnosis for young to middle-aged dogs with progressive neurological signs, focal or multifocal computed tomography/magnetic resonance imaging lesions, mononuclear cerebrospinal fluid pleocytosis and negative infectious titres includes granulomatous meningoencephalomyelitis, breed-specific meningoencephalitis, infectious meningoencephalitis of unknown origin and central nervous system neoplasia. The terminology meningoencephalitis of unknown aetiology may be preferable for cases that lack histopathological diagnoses. The safety and efficacy of a combination of cytosine arabinoside and prednisone protocol is evaluated, in this study, for the treatment of meningoencephalitis of unknown aetiology in 10 dogs. METHODS: Cases were selected based on neuroanatomical localisation, negative regional infectious disease titres, cerebrospinal fluid pleocytosis and brain imaging. Clinical response was gauged through follow-up examinations, owner and referring veterinarian surveys and review of medical records. RESULTS: Partial or complete remission was achieved in all dogs; the median survival time for the 10 dogs was 531 days (range 46 to 1025 days), with five of the 10 dogs alive at the time of writing. CLINICAL SIGNIFICANCE: Prednisone/cytosine arabinoside is a safe empirical therapy for dogs with meningoencephalitis of unknown aetiology; this drug combination may prolong survival time.     

Distemper in Nigerian dogs and its differentiation from rabies

Four cases of distemper in Nigerian dogs with nervous signs similar to those of rabies are described. Two of them died: postmortem examination and laboratory tests confirmed the presence of distemper and the absence of rabies. The other two dogs recovered.     

Neurological manifestations in dogs naturally infected by Leishmania infantum: descriptions of 10 cases and a review of the literature

In order to evaluate possible nervous system involvement in canine leishmaniasis, retrospective evaluation of all medical records of leishmaniotic dogs exhibiting neurological signs referred to our hospital over a 5‐year period was performed. The records of 10 dogs were reviewed. Depending on the neuroanatomical localisation, the dogs underwent advanced diagnostic imaging, cerebrospinal fluid analysis, electrodiagnostic testing and histopathologic evaluations. The final neurological diagnosis was: meningoencephalitis (n=2), brain haemorrhagic stroke (n=1), haemorrhagic choroiditis (n=1), meningomyelitis (n=2), ischaemic myelopathy (n=1), polymyositis (n=2) and peripheral neuropathy (n=1). This study confirms that both central and peripheral nervous systems can be affected by leishmaniasis and provides an overview on the possible etiopathogenetic mechanisms. In addition, clinical and diagnostic findings, therapy and follow‐up of affected dogs are described.     

Examination of cerebrospinal fluid in the horse

The examination of cerebrospinal fluid (CSF) is often part of the diagnostic work-up of a patient exhibiting signs of disease involving the central nervous system. Awareness of the capabilities and limitations of these laboratory tests is important in assessing the benefit-to-risk ratio of performing such procedures. Collection of CSF is a relatively simple procedure, and together with a thorough history, physical examination, and other diagnostic tests, may be a valuable aid in arriving at a diagnosis or prognosis.     

自发性急性犬瘟热的原发性脱髓性脑病

为了进一步观察犬瘟热病毒引起的原发性脑损伤和包涵体形成的特点，调查脑组织的损伤与神经症状的关系，对10只急性犬瘟热病犬的脑组织进行了详细的病理学研究。为了仔细地观察病变，本试验按照解剖学关系将脑组织分成3个大部分和11个切面，即大脑(4个切面)，脑干(5个切面)和小脑(2个切面)。组织切片经HE、LFB和免疫组织化学染色后进行检查，结果表明：在大脑，脱髓呈弥漫性发生，程度较轻；脑干的周围或靠近第三脑室的白质脱髓较重；小脑在轻度或中度脱髓的基础上常出现严重的多发性脱髓灶。脱髓部呈空泡或海绵状，有少量胶质细胞存在，但无炎性反应。脱髓性病损是非时称性发生，对神经束没有特殊的亲和力。在脑室的室管膜细胞内发现有较多的嗜酸性胞浆或核内包涵体。用抗犬瘟热病毒抗体染色，带有包涵体的室管膜细胞呈现强阳性反应。部分锥体细胞，神经核细胞和漓氏细胞变性、溶解或胞浆深染。胞核浓缩。这种变化以小锥体神经细胞表现得最为明显。根据此研究结果，作者认为由犬瘟热病毒引起的原发性脑组织损伤是一种脱髓性脑病，而不是脑炎变化；位于室管膜细胞内的包涵体对于脑组织犬瘟热的确诊具有重要的作用；由于犬瘟热病毒引起神经细胞的损伤是非特异性的，对脑组织的侵害是非对称性的。对神经束的作用无特殊的亲和力，所以患犬瘟热的犬在临床上可出现不同的神经症状。     

Partial protection and intrathecal invasion of CD8(+) T cells in acute canine distemper virus infection

Initial non-inflammatory demyelination in canine distemper virus infection (CDV) develops against a background of severe immunosuppression and is therefore, thought to be virus-induced. However, recently we found a marked invasion of T cells throughout the central nervous system (CNS) in dogs with acute distemper despite drastic damage to the immune system. In the present study, this apparent paradox was further investigated by immunophenotyping of lymphocytes, following experimental CDV challenge in vaccinated and non-vaccinated dogs. In contrast to CDV infected, unprotected dogs, vaccinated dogs did not become immunosuppressed and exhibited a strong antiviral immune response following challenge with virulent CDV. In unprotected dogs rapid and drastic lymphopenia was initially due to depletion of T cells. In peripheral blood, CD4(+) T cells were more sensitive and depleted earlier and for a longer time than CD8(+) cells which recovered soon. In the cerebrospinal fluid (CSF) we could observe an increase in the T cell to B cell and CD8(+) to CD4(+) ratios. Thus, partial protection of the CD8(+) cell population could explain why part of the immune function in acute distemper is preserved. As found earlier, T cells invaded the CNS parenchyma in these dogs but also in the protected challenged dogs, which did not develop any CNS disease at all. Since markers of T cell activation were upregulated in both groups of animals, this phenomenon could in part be related to non-specific penetration of activated T cells through the blood brain barrier. However, in diseased animals much larger numbers of T cells were found in the CNS than in the protected dogs, suggesting that massive invasion of T cells in the brain requires CDV expression in the CNS.     

Labile neurotoxin in serum of calves with "nervous" coccidiosis

Mouse inoculation was used to test for the presence of a toxin in the serum, cerebrospinal fluid, and intestinal contents collected from cases of bovine enteric coccidiosis, with and without neurological signs, and from control calves. Intravenous inoculation of mice with 10 mL/kg of serum from calves showing nervous signs caused effects significantly different from those caused by the inoculation of serum from calves not showing nervous signs and from control calves. The effect was particularly evident in female mice. At this dosage severe neurological signs such as loss of righting reflex, seizures and death occurred only with serum from calves with "nervous coccidiosis". The results suggest that serum from the calves with neurological signs contains a neurotoxin. This toxin appears to be highly labile. It was not present in the cerebrospinal fluid at levels comparable to those in the serum. The significance of this labile neurotoxin with respect to the pathogenesis of the neurological signs associated with bovine enteric coccidiosis is unknown.     

Chronic encephalomyelitis caused by canine distemper virus in a Bengal tiger

A chronic progressive neurologic disease was observed and monitored for 18 months in a young, tamed Bengal tiger. Clinical, serologic, and neuropathologic evidence of canine distemper virus infection was seen. Clinical signs included convulsions, myoclonus, and slowly progressive ataxia. Marked increases in neutralizing antibodies against canine distemper virus were seen in the serum and cerebrospinal fluid. Neuropathologic findings were nonsuppurative meningoencephalomyelitis, with perivascular cuffing, demyelination, and inclusion bodies typical of canine distemper virus. It was concluded that, in light of this case and an earlier report of canine distemper in lion cubs, vaccination of this subgroup of carnivores with a killed vaccine may be beneficial if exposure to other animals susceptible to canine distemper is anticipated.     

Brain and spinal cord haemorrhages associated with Angiostrongylus vasorum infection in four dogs

Multifocal haemorrhages associated with Angiostrongylus vasorum infection were observed in the central nervous system of four dogs with neurological signs including depression, seizures, spinal pain and paresis. In magnetic resonance images the majority of the lesions were isointense or slightly hyperintense in T1-weighted images, hyperintense in T2-weighted images and hypointense in T2*-weighted (gradient echo) images, compatible with haemorrhages more than seven days old. Lesions were found in the brain of three of the dogs and in the spinal cord of two. The cerebrospinal fluid contained high concentrations of protein and evidence of erythrophagia. All the dogs had coagulopathy and pulmonary haemorrhage of varying severity. A vasorum larvae were detected in the faeces of each of the dogs. Neural A vasorum was confirmed at postmortem examination in two dogs.     

Clinical signs and diagnosis of BSE

Bovine spongiform encephalopathy (BSE) in cattle is characterised by typical signs and an insidious course. There is gradual weight loss and decreased milk production, and the disease is distinguished by disturbances in behaviour, sensitivity and locomotion. The most common behavioural changes are apprehension and abnormal temperament. The most common changes in sensitivity are hypersensitivity to tactile, auditory and optical stimuli, kicking during milking and excessive licking of the muzzle. The most important disturbances in locomotion include ataxia, falling down and inability to get up. Diagnostic procedures include a thorough clinical and neurological examination followed by a more detailed examination to assess behaviour, locomotion and sensitivity to touch, sound and light stimuli. Other causes of central nervous system disease may be ruled out by a complete blood count, biochemical profile, urinalysis and examination of cerebrospinal fluid. Disturbances in behaviour, locomotion and sensitivity that occur singly, rather than in combination with each other, should be interpreted with caution. However, in cattle with disturbances in two or more of these categories, a tentative diagnosis of BSE can be made, and the veterinary authorities must be notified.     

Lumbosacral myelography in dogs--a safer technique

In search of a safer myelographic technique, we performed myelography via the lumbosacral intervertebral space. Eight dogs, in which the backflow of cerebrospinal fluid was observed, received contrast media via the lumbosacral intervertebral space. The subarachnoid contrast columns were successfully observed in 6 dogs. During and after examination, no physiological changes or neurological signs were observed. We recommend that the lumbosacral intervertebral space be selected first before implementing the conventional lumbar myelography.