Neurotropic T-cell-rich B-cell lymphoma in a 14-year-old Morgan gelding

A 14-year-old Morgan gelding was presented for progressive weakness and muscle atrophy. The horse was initially diagnosed with equine protozoal myelitis based on history, physical examination, and laboratory diagnostics. Despite therapy, the horse declined clinically and was euthanized. Necropsy revealed a rare form of neurotropic lymphoma, described in this report.

An unusual case of spinal cord restricted mycobacteriosis in a European mink

Granulomatous myelitis due to infection with Mycobacterium avium was diagnosed in a 4-year-old male neutered European mink (Mustela lutreola). The causative agent was detected by an acid-fast stain and further characterized by polymerase chain reaction and DNA sequencing of the PCR product. A thorough histological evaluation of the remaining organs revealed no granulomatous lesions or detectable acid-fast organisms. Although minks are generally highly susceptible for mycobacteria, localised infections, especially of the central nervous system, are unusual and may represent an atypical chronic form of the disease.

Beta-2-microglobulin levels in the cerebrospinal fluid of normal dogs and dogs with neurological disease

BACKGROUND

Cerebrospinal fluid (CSF) analysis is the basis for establishing a diagnosis of central nervous system (CNS) inflammation. However, the information provided by routine CSF analysis is limited. Determination of CSF beta-2-microglobulin (beta2m) concentration has been used diagnostically in humans to identify inflammatory CNS disease; we hypothesized that it may have similar value in dogs.

OBJECTIVES

The objective of this study was to measure (beta2m concentration in the CSF of clinically healthy dogs and compare the values to those observed in dogs with inflammatory CNS disease and intervertebral disc disease (IVDD).

METHODS

CSF was collected from 10 clinically healthy laboratory dogs and 11 dogs each with inflammatory CNS disease and IVDD. Routine CSF analysis was performed, and (beta2m concentration was measured by ELISA. CSF (beta2m concentration and CSF:serum (beta2m ratio were compared between groups by ANOVA. Linear relationships between CSF total nucleated cell count (TNCC), RBC count, total protein concentration, and (beta2m concentration were assessed by regression analysis.

RESULTS

The mean (+/- SD) CSF (beta2m concentration in clinically healthy dogs was 0.36 (+/- 0.05 microg/mL (cisternal) and 0.40 (+/- 0.07 microg/mL (lumbar). Median CSF (beta2m concentration in dogs with IVDD (0.46 microg/mL) and inflammatory CNS disease (0.85 microg/mL) differed from that of controls (0.36 microg/mL; P=.002). The concentration also differed between the 2 disease groups (P=.01). Five dogs with inflammatory CNS disease had CSF:serum (beta2m ratios >1. A correlation was identified between TNCC and (beta2m concentration (r=0.69, P=.0003).

CONCLUSIONS

CSF (beta2m concentration is higher in dogs with IVDD and inflammatory CNS disease, with highest values seen with inflammatory disease. This may be attributed in part to the correlation between CSF (beta2m concentration and TNCC, but also may reflect intrathecal immune activation.

Natural cases of visna in sheep with myelitis as the sole lesion in the central nervous system

Of 118 sheep with visna, 12 showed myelitis as the only nervous lesion. They were ovine lentivirus (OvLV)-seropositive and provirus DNA was demonstrated by LTR-PCR in all the samples with lesions. Clinically, all showed hindlimb paralysis and some were completely recumbent. Grossly, a swollen and discoloured area was identified in the white matter in 10 sheep. Microscopical changes consisted of a wedge-shaped area of non-suppurative leucomyelitis with mononuclear perivascular cuffing, demyelination and white matter degeneration. Except for two samples, grey matter was affected adjacent to severe white matter lesions. Three different microscopical patterns of lesion were identified, all having in common the presence of perivascular inflammation: the so-called vascular pattern was characterized by perivascular cuffs with minimal lesions in the adjacent neuroparenchyma; the malacic pattern, which was the commonest type, was characterized by severe white matter destruction and small numbers of macrophages; and the infiltrative pattern was characterized by a severe infiltrate of histiocytes in the parenchyma. Maedi-visna virus antigen was detected immunohistochemically only in areas with lesions, and the degree of immunolabelling was unrelated to the severity of the damage. Diagnosticians should bear in mind that a considerable number of visna cases show only spinal cord lesions. Examination of paraffin wax-embedded samples by LTR-PCR and immunohistochemistry would seem useful in confirming a histopathological diagnosis of visna from spinal cord samples.

MAGNETIC RESONANCE IMAGING CHARACTERISTICS OF ASCENDING HEMORRHAGIC MYELOMALACIA IN A DOG

A 4-year-old neutered female terrier-cross was evaluated for an acute onset of paraplegia. Utilizing magnetic resonance (MR) imaging, the cause of the neurologic deficits was determined to be a lumbar intervertebral disc extrusion. The MR study additionally demonstrated parenchymal hyperintensity on T2-weighted images and similarly located diffuse hypointensity on gradient echo images, cranial and caudal to the compressive extradural lesion. Hemorrhagic myelomalacia was suspected based on these MR characteristics, which was subsequently confirmed surgically and histopathologically.

Myasthenia Gravis and Hypothyroidism in a Dog With Meningomyelitis

A 12-year-old, spayed female miniature poodle was evaluated because of a 4-day history of paraparesis, dysuria, and tenesmus. Neurological assessment suggested peripheral nervous system dysfunction, predominantly pelvic limb weakness with a possible concurrent sixth lumbar (L6) to second sacral (S2) myelopathy. Further studies supported the diagnoses of myasthenia gravis, hypothyroidism, and meningomyelitis. To the authors’ knowledge, this is the first reported case of concurrent myasthenia gravis and meningomyelitis in the dog. It was unclear whether the identified conditions evolved from a shared etiopathogenesis or were merely coincidental.

Ovine lentivirus-associated leucomyelitis in naturally infected North American sheep

Leucomyelitis was the predominant feature in four North American adult sheep (cases 1-4) with ovine lentivirus (OvLV) infection. All four animals were OvLV-seropositive and a syncytogenic virus consistent with OvLV was isolated from the brain of case 3 and the lungs of case 4. Clinically, the sheep had dyspnoea and neurologic signs of varying severity. Changes in the central nervous system included asymmetrical meningoleucomyelitis with white matter degeneration in all four sheep and scattered foci of leucoencephalitis in periventricular, subependymal and other white matter areas of the brain of the three animals (cases 1, 2 and 4) for which the brain was examined. In the lungs of two sheep (cases 3 and 4), there was lymphoid interstitial pneumonia with marked lymphoid hyperplasia. The viral capsid antigen (p25) was detected by immunohistochemistry (IHC) in sections of lung, brain and spinal cord of the four sheep and OvLV RNA was detected by in-situ hybridization (ISH) in lung and spinal cord samples. The results confirm the usefulness of the IHC and ISH for differential diagnosis of visna.

Atypical parasitic migration and necrotizing sacral myelitis due to Serratospiculoides amaculata in a prairie falcon (Falco mexicanus)

An adult, wild-caught, female prairie falcon (Falco mexicanus) was presented with the chief complaint of anorexia. Radiographic findings included increased densities within the air sacs, and coelomic endoscopy revealed numerous slender worms within the air sacs and on the serosal surfaces of the ovary, oviduct, liver, proventriculus, and ventriculus. The bird seemed to improve for a short period of time with antiparasitic therapy (ivermectin and fenbendazole) and supportive care. Twenty-one days after initial presentation, the bird became recumbent with increasing pelvic limb neurologic deficits and was euthanized. On histopathologic examination, mature nematodes and larvated eggs identified as Serratospiculoides amaculata were found within the subdural space of the distal thoracolumbar and synsacral spinal cord and within the coelomic cavity. This case suggests that S. amaculata can cause clinically significant lesions in its falconiform host with potentially fatal results.

Dermoid sinus at the lumbosacral junction in an English springer spaniel

A dermoid sinus was identified in a springer spaniel that presented with hindlimb neurological deficits. The sinus was continuous with the dura mater at the level of the lumbosacral junction. The presence of hair and debris adjacent to neural tissue had elicited a myelitis. A dorsal laminectomy was required to allow complete surgical resection of the sinus. The dog's neurological status improved after treatment and this improvement was maintained over a five-month follow-up period.

Prevalence of antibodies to Neospora sp. in horses from Alabama and characterisation of an isolate recovered from a naturally infected horse [corrected]

An IFAT was used to determine the prevalence of Neospora-specific IgG antibodies in serum from Alabama horses. Serum samples (n = 536) were from asymptomatic horses routinely submitted for equine infectious anaemia virus infection testing. We also subjected a 13-year-old horse with CNS disease to necropsy examination for isolation and in vitro cultivation of protozoal organisms. In antemortem tests, this horse was positive for antibodies to Neospora sp. in the IFAT and western immunoblot. Results of the prevalence survey indicated that IgG antibodies to Neospora were present in 62 (11.5%) of the 536 serum samples. Endpoint titres for the positive samples were 1:50 (35/6.5%), 1:100 (19/3.5%), 1:200 (7/1.3%) and 1:1600 (1/0.2%). Tachyzoites were first seen in cultured bovine turbinate cells 32 days after inoculation with spinal cord homogenates from the horse with CNS disease. Tachyzoites reacted with known N. caninum-positive serum from horses, cows, dogs and mice, but did not react with murine anti-Toxoplasma gondii or equine anti-Sarcocystis neurona serum. Ultrastructural features of tachyzoites and results of comparison of tachyzoite immunodominant proteins revealed that they were identical to those of N. hughesi, a species described recently from a naturally infected horse. The isolate recovered from the naturally infected horse in the present study (designated NA1) is thought to be an isolate of N. hughesi, although confirmation of this awaits additional molecular characterisation. These results provide some additional evidence that N. hughesi is a valid species and that Neospora infections in horses may occur in widely separated geographic regions of the United States.

The diagnostic utility of cerebrospinal fluid creatine kinase activity in the horse

We evaluated creatine kinase (CK) activity in the cerebrospinal fluid (CSF) of 128 horses with various neurological disorders. No association was found between CSF CK activity and CSF red blood cell count, CSF nucleated cell count, CSF total protein concentration, or serum CK activity. The sensitivity and specificity of CSF CK activity as a diagnostic test for protozoal myelitis in horses (61% and 56%, respectively) was higher than for cervical stenotic myelopathy, degenerative myelopathy, or motor neuron disease, but was considered to be inadequate to be of use diagnostically. Contamination of CSF with whole blood, hemolyzed red blood cells, or serum did not substantially contribute to increases in CSF CK activity. Addition of epidural fat or dura to CSF significantly increased CSF CK activity in all cases. We suggest that the use of CSF CK activity as a diagnostic indicator of neurological disease in the horse in unreliable, and that CSF CK activity may be falsely increased by contamination of CSF with epidural fat or dura during CSF collection.

Spinal cord swelling as a myelographic indicator of prognosis: a retrospective study in dogs with intervertebral disc disease and loss of deep pain perception

The association of myelographic spinal cord swelling with neurological outcome was examined in 46 dogs with intervertebral disc disease and absence of deep pain perception (DPP). Spinal cord swelling was measured by calculating a ratio of the length of the loss of the myelographic dye column to the length of the second lumbar vertebra (L2). A positive neurological outcome was defined as return of voluntary motor function. A cut-off value for swelling:L2 of 5.0 was established by the creation of a receiver operator characteristic curve. Using a swelling:L2 ratio of 5.0 as a cutoff for indication of neurological recovery yielded a sensitivity of 74% and a specificity of 61%. Overall neurological recovery rate was 43%. Dogs with spinal cord swelling:L2 ratios less than 5.0 had a recovery rate of 61%, whereas dogs with a ratio greater than or equal to 5.0 had a recovery rate of 26%. Evaluation of these data by chi square analysis confirmed that a ratio less than 5.0 was associated with a positive outcome, and a ratio greater than or equal to 5.0 was associated with a negative outcome, (P < .05). Although other factors, such as duration of neurological signs, affect neurological outcome in dogs with no DPP, evaluation of myelographic spinal cord swelling can assist in establishing a prognosis.

Neospora-induced congenital myelitis and polyradiculoneuritis in a one-month-old Holstein calf

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Equine protozoal myelitis in Panamanian horses and isolation of Sarcocystis neurona

Schizonts of Sarcocystis neurona were identified microscopically in hematoxylin-eosin-stained spinal cord sections from 2 native Panamanian horses that exhibited clinical signs of equine protozoal myelitis (EPM). Spinal cord homogenate from a third Panamanian horse with EPM was inoculated onto monolayers of cultured bovine monocytes (M617). Intracytoplasmic schizonts containing merozoites arranged in rosette forms surrounding a central residual body first were observed 13 wk postinoculation. Parasites divided by endopolygeny and lacked rhoptries. Schizonts from each horse reacted with Sarcocystis cruzi antiserum in an immunohistochemical test.

Myelitis and meningitis

Animals with meningomyelitis have clinical neurologic signs that typically range from paraspinal discomfort to tetraplegia; however, most affected animals also show evidence of multifocal CNS involvement with brain stem and cerebral cortical structures being affected most commonly. The cause, duration, and host response to the disease process will determine the clinical signs in individual animals. Confirmation of a specific causative agent is difficult, but CSF analysis and immunotesting of serum and CSF yield the most rewarding diagnostic results. Successful treatment is based on formulation of an appropriate and aggressive therapeutic regimen. In some diseases, no effective treatment is available, and some animals may develop permanent neurologic disabilities.

In vitro cultivation of Sarcocystis neurona from the spinal cord of a horse with equine protozoal myelitis

Asexual stages of Sarcocystis neurona were seen in cultured bovine monocytes (M617) inoculated with tissue homogenates from the spinal cord of a horse with naturally acquired protozoal myelitis. Organisms first were observed as intracytoplasmic schizonts and later as motile extracellular zoites capable of infecting surrounding M617 cells. Parasites most often occurred as clusters of merozoites dispersed throughout the host cell cytoplasm; however, schizonts also contained merozoites arranged in a radial fashion surrounding a prominent residual body. Schizonts divided by endopolygeny. The parasite has been maintained beyond 280 days in the laboratory by serial passage of infected M617 cells.

Nematode related spinal myelomeningitis and posterior ataxia in muskoxen (Ovibos moschatus)

In the fall of 1988 all five animals in a herd of muskoxen (Ovibos moschatus) developed clinical signs of posterior ataxia. Postmortem investigation revealed inflammatory lesions of the caudal part of the spinal cord, mainly as leptomeningitis. Nematodes were seen in close association with the lesions. Although not identified, the parasites were probably an Elaphostrongylus sp.

Myelitis in a cat infected with Toxoplasma gondii and feline immunodeficiency virus

Severe necrotizing myelitis secondary to localization and reactivation of Toxoplasma gondii within the spinal cord of a domestic shorthair cat was diagnosed by use of light and electron microscopy and immunohistochemistry. The cat also was infected with feline immunodeficiency virus. This case may have useful comparative features to T gondii infections in human patients with acquired immunodeficiency syndrome.

Neospora caninum-like protozoon associated with fatal myelitis in newborn calves

Neospora caninum-like organisms were found in histologic sections of spinal cord of 4 paralyzed calves as reported by Parish et al. (1987). Tachyzoites divided by endodyogeny. Tissue cysts were up to 62 microns wide and the cyst wall was up to 2.5 microns thick. The organism in calves was structurally distinct from Toxoplasma gondii and Sarcocystis species and reacted positively with anti-N. caninum serum in an immunoperoxidase test.

Inflammatory disease of the central nervous system

Inflammatory diseases involving the central nervous system can be difficult to diagnose and frustrating to treat. The clinician can maximize successful treatment of these patients by recognizing the clinical signs in the early stages of disease, following a logical diagnostic plan to identify the specific etiologic agent involved, and formulating an appropriate and aggressive therapeutic plan. Treatment will not always be successful owing to lack of effective treatments and irreversible neurologic damage.

Myelitis associated with protozoal infection in newborn calves

Four newborn calves from different herds were examined because of recumbency and inability to rise. Abnormal physical findings were confined to the nervous and/or musculoskeletal systems. Because of poor prognosis, all calves were euthanatized and necropsied. The histopathologic findings were multifocal lymphocytic myelitis, meningitis, and encephalitis associated with protozoal cysts.

Sequential morphological and quantitative changes in blood and bone marrow neutrophils in dogs with acute inflammation

Blood and bone marrow morphology were studied sequentially in dogs during experimental inflammation induced by intramuscular injection of turpentine. Depletion of the bone marrow storage pool of mature neutrophils and an increase in mitotic activity and number of early granulocyte precursors were evident within 24 hours. During the next three days, intense granulocytic hyperplasia resulted in replenishment of the bone marrow storage pool. Neutrophils with foamy vacuolation and increased basophilia of the cytoplasm (toxic neutrophils) were present in the blood by eight hours postinjection. The number of toxic neutrophils paralleled the intensity of clinical signs and changes in rectal temperature but not the number of band neutrophils. This indicates that changes in number of toxic neutrophils in sequential leukograms can be a prognostic indicator in dogs with severe inflammation.

Neurologic diseases

The responses of apparently healthy newborn foals to neurologic testing differ significantly from those of adult horses. These responses and the diagnostic techniques pertinent to neurologic problems are reviewed as a basis for evaluation of the compromised neonatal foal. The more frequently encountered neurologic diseases are discussed in a problem-oriented format. These clinical problems include behavioral abnormalities, convulsions, changes in consciousness, blindness, ataxia without loss of strength, ataxia with weakness and paralysis, and the floppy foal.

Acute meningoencephalomyelitis in a rabbit infected with Pasteurella multocida

Pasteurella multocida was isolated in pure culture from the optic chiasm of a rabbit that was euthanatized subsequent to acute development of neurological signs. Histopathologically, there was meningoencephalomyelitis, bilateral otitis interna, retrobulbar cellulitis, optic neuritis and iritis. The ocular involvement, severity of the spinal lesions and the lack of otitis media was unusual.

Verminous (Strongylus vulgaris) myelitis in a donkey

A fifth stage Strongylus vulgaris migrated through the spinal cord of a 2-year-old, male donkey resulting in progressive paraparesis and then tetraplegia. A profound neutrophilic pleocytosis was detected on analysis of cerebrospinal fluid. The parasite appeared to have entered the mid-lumbar spinal cord, migrated to the cranial thoracic segments, exited, then re-entered the spinal cord a few segments craniad. It then traveled further cranially and was found in the third cervical spinal cord segment. Some parts of the lesion were remarkably free from tissue necrosis, hemorrhage and inflammation. Severe granulomatous myelitis with hemorrhage and necrosis were seen at other sites. The latter were quite similar to lesions seen in equine protozoal myeloencephalitis.

Visna virus meningoencephalomyelitis in goats

A progressive paresis was encountered in herds of Swedish goats. The symptoms developed during a period of weeks or months, and were initially often seen as a weakness of the hind limbs before the animals became paralytic. The development and the histopathological lesions of the disease in the GNS and the lungs were similar to those of visna in sheep. In vitro grown choroid plexus cells, prepared from affected goats, showed foci of polykaryocytes. Electron microscopy revealed the presence of particles morphologically similar to those of sheep visna virus (SVV). Goats experimentally infected with the goat visna virus (GVV) developed GNS lesions similar to those of visna in sheep and became seropositive to SVV. The results of complement fixation tests, carried out on sera from 11 goat herds, showed a coincidence between seropositiveness and the occurrence of disease in one and the same herd. Using the ELISA method, an average of 80 % of the goats in 5 herds were found to be seropositive to GVV.