Inositol 1,4,5-triphosphate receptor protein immunohistochemistry of cerebellar Purkinje cells in two dogs with hypoglycemia

Immunohistochemical study was performed on cerebellar Purkinje cells of two dogs with hypoglycemia using an antibody against the inositol 1,4,5-triphosphate receptor that is identical to the cerebellar Purkinje cell glycoprotein P(400) (P(400)/InsP(3)R). In the cerebellar neocortex of an acute case of hypoglycemia, the P(400)/InsP(3)R staining of hypoglycemic Purkinje cells was heterogeneous: some peripheral dendrites, including spiny branchlets, were negative and others were stained with various intensities, although Purkinje cells were morphologically intact by hematoxylin and eosin (HE) stain. In a chronic case of hypoglycemia, almost all the dendrites of Purkinje cells of both the neo- and archicortex of the cerebellum were not stained with the P(400)/InsP(3)R antibody. This is in contrast to the normal dog where Purkinje cell bodies, axons, and dendrites, including spiny branchlets, are intensely stained by the P(400)/InsP(3)R antibody. These results suggest that P(400)/InsP(3)R immunolabeling of Purkinje cells decreased, despite their morphology being preserved by HE stain, and that the function of P(400)/InsP(3)R, especially in spiny branchlets that receive inputs originating from axon terminals of parallel fibers, may be impaired in hypoglycemia.     

Purkinje cell apoptosis in arabian horses with cerebellar abiotrophy

Purkinje cerebellar cells were studied in three Arabian horses aged between 6 and 8 months with clinical disorders in their movements, tremors and ataxia; the occurrence of apoptosis in this cell population was investigated by the (terminal deoxynucleotidyl transferase biotin-dUTP nick-end labelling (TUNEL) method. Both optical and electron microscopical images showed a scant number of Purkinje cells, most of them with morphological features of apoptosis such as condensation of the nucleus and cytoplasm as well as segregation and fragmentation of the nucleus into apoptotic bodies. The TUNEL technique revealed a substantial number (65%) of positive immunoreactive Purkinje cells.     

Neonatal cerebellar ataxia in Coton de Tulear dogs

A neonatal ataxia syndrome was observed in Coton de Tulear dogs. Seven affected pups (32%; 7/22) of both genders came from 5 different litters with phenotypically normal parents. Neurologic examination revealed normal mental status, head titubation, intention tremors, and severe gait, stance, and ocular ataxia beginning at 2 weeks of age. One of the pups was able to walk with assistance, but most of the affected pups were unable to stand and used propulsive movements ("swimming") for goal-oriented activities. They frequently would fall to lateral recumbency with subsequent decerebellate posturing and paddling. Ocular motor abnormalities included fine vertical tremors at rest and saccadic dysmetria. The condition was nonprogressive at least until 4 months of age. No specific abnormalities were identified in routine laboratory screening of blood and urine. Cerebrospinal fluid (CSF) analysis was normal in 1 dog, and a mild increase in protein concentration was observed in a second dog. CSF organic and amino acid concentrations were within normal limits. Magnetic resonance imaging and computed tomography of the brain, electromyography, motor nerve conduction studies, and brain stem auditory-evoked potentials were within normal limits. Postmortem examinations were performed on 5 affected dogs between 2 and 4 months of age. Routine light microscopic and immunocytochemical examination of brain, spinal cord, peripheral nerve, and muscle did not disclose any gross or histologic lesions. Compared with the cerebellum from an age-matched normal dog, the cerebellum from an affected dog showed synaptic abnormalities, including loss of presynaptic terminals and organelles associated with parallel fiber varicosities within the molecular layer and increased numbers of lamellar bodies in Purkinje cells. An autosomal recessive trait affecting development of the cerebellum is suspected.     

Mapping of Purkinje neuron loss and polyglucosan body accumulation in hereditary cerebellar degeneration in Scottish terriers

A hereditary cerebellar degenerative disorder has emerged in Scottish Terriers. The aims of this study were to describe and quantify polyglucosan body accumulation and quantify Purkinje neurons in the cerebellum of affected and control dogs. The brains of 6 affected Scottish Terriers ranging in age from 8 to 15 years and 8 age-matched control dogs were examined histopathologically. Counts of Purkinje neurons and polyglucosan bodies were performed in control and affected dogs on cerebellar sections stained with periodic acid-Schiff. Affected dogs showed a significant loss of Purkinje neurons compared with control dogs (vermis: P < .0001; hemisphere: P = .0104). The degeneration was significantly more pronounced dorsally than ventrally (P < .0001). There were significantly more polyglucosan bodies in the ventral half of the vermis when compared with the dorsal half (P < .0001) in affected dogs. In addition, there were more polyglucosan bodies in the ventral half of the vermis in affected dogs than in control dogs (P = .0005). Polyglucosan bodies in all affected dogs stained positively with toluidine blue and alcian blue. Immunohistochemically, polyglucosan bodies in affected dogs were positive for neurofilament 200 kD and ubiquitin and negative for glial fibrillary acidic protein, synaptophysin, neurospecific enolase, vimentin, and S100; the bodies were negative for all antigens in control dogs. Ultrastructurally, polyglucosan bodies in 1 affected dog were non-membrane-bound, amorphous structures with a dense core. This study demonstrates significant Purkinje cell loss and increased polyglucosan bodies in the cerebellum of affected Scottish Terriers.     

Suspected inherited cerebellar neuroaxonal dystrophy in collie sheep dogs

A cerebellar neuroaxonal dystrophy in working collie sheep dogs from two properties in New Zealand and one property in Australia is described. Clinical signs developed from 2-4 months of age and included hypermetria, wide-based stance, difficulty in maintaining balance, intention tremor and ataxia. Numerous spheroids, associated with mild Wallerian degeneration, were present in the central cerebellar, adjacent peduncular and folia white matter, and associated cerebellar roof and lateral vestibular nuclei. The history of several affected pups in litters from successive matings of the same sire and dam is suggestive of an autosomal recessive mode of inheritance.     

Suspected inherited cerebellar neuroaxonal dystrophy in collie sheep dogs

A cerebellar neuroaxonal dystrophy in working collie sheep dogs from two properties in New Zealand and one property in Australia is described. Clinical signs developed from 2–4 months of age and included hypermetria, wide-based stance, difficulty in maintaining balance, intention tremor and ataxia. Numerous spheroids, associated with mild Wallerian degeneration, were present in the central cerebellar, adjacent peduncular and folia white matter, and associated cerebellar roof and lateral vestibular nuclei. The history of several affected pups in litters from successive matings of the same sire and dam is suggestive of an autosomal recessive mode of inheritance.     

Diseases of the adrenal cortex of dogs and cats

Of cases of hyperadrenocorticism in small animals 80-85% are the result of adrenocortical hyperplasia. Middle-aged or older Poodles, Dachshunds, Boston Terriers and Boxers are most commonly affected, and cats rarely. Clinical signs include polydipsia, polyuria, alopecia, abdominal distension, lethargy, weakness, hepatomegaly, calcinosis cutis, testicular atrophy and anestrus. Hematologic and biochemical changes may include neutrophilia, lymphopenia, monocytosis, eosinopenia, increased blood levels of alkaline phosphatase, SGPT, cholesterol, Na and glucose, and decreased K and T4 levels. The high-dosage dexamethasone suppression test helps differentiate pituitary-dependent hyperadrenocorticism from that caused by adrenal tumors. The low-dosage dexamethasone suppression test, determination of plasma ACTH levels, and ACTH response test are additional diagnostic aids in the diagnosis of Cushing's disease. Medical treatment involves oral use of mitotane (o,p'-DDD) at 50 mg/kg/day for 7 days and prednisone or prednisolone at 0.05 mg/kg/day. Hypophysectomy has been used with only 5% mortality in cases of pituitary-dependent hyperadrenocorticism. Adrenalectomy is indicated in cases of adrenal neoplasia.     

Diseases of the adrenal cortex of dogs and cats

The most common cause of hypoadrenocorticism in dogs is idiopathic immune-mediated destruction of the adrenal cortex. Other causes include anterior pituitary insufficiency, pituitary or adrenal neoplasia, acute withdrawal of exogenous corticosteroids, and mitotane toxicity. Females are affected more often than males; only 1 feline case has been documented. Animals 2-5 years old are most commonly affected. Clinical signs include lethargy, weakness, weight loss, anorexia, vomiting, diarrhea and bradycardia. Hematologic and biochemical changes can include eosinophilia, lymphocytosis, anemia, hyperkalemia, hyponatremia and hypercalcemia. Diagnosis is by finding negligible resting levels of plasma cortisol and no response to ACTH administration, and a serum Na:K ratio of 20:1 or less. Treatment involves restoring fluid volume, correcting acidosis, and supplementing salt and glucocorticoids. Daily oral use of prednisone at 0.05 mg/kg can safely maintain most affected dogs. Some dogs only require glucocorticoids in stressful situations. Iatrogenic secondary adrenocortical insufficiency (iatrogenic Cushing's disease) may result from a single injection of long-acting glucocorticoids or from long-term use. Clinical signs are the same as for natural hyperadrenocorticism, but endogenous cortisol release is suppressed. Treatment is gradual withdrawal of the offending glucocorticoid and elimination of the cause that initially prompted glucocorticoid therapy.     

Clinicopathological features of canine neuroaxonal dystrophy and cerebellar cortical abiotrophy in Papillon and Papillon-related dogs

Neuroaxonal dystrophy (NAD) was examined in two Papillon dogs and a mix breed dog between Papillon and Chihuahua. In addition, cerebellar cortical abiotrophy (CCA) in a Papillon dog, which had similar clinical and magnetic resonance imaging (MRI) features to those of NAD, was also investigated. The common clinical symptoms of all dogs affected with NAD and CCA, were pelvic limb ataxia and cerebellar ataxia including intention tremor, head tremor, and hypermetria in the early onset. These clinical signs were progressed rapidly, and two dogs with NAD were euthanized by owner's request and the other two died by aspiration pneumonia. MRI examinations and gross observations at necropsy revealed moderate to severe cerebellar atrophy in all cases of NAD and CCA. The most typical histological change of NAD was severe axonal degeneration with marked spheroid-formation in the dorsal horn of the spinal cords, the nuclei gracilis, cuneatus, olivalis and its circumference in the medulla oblongata. The spheroids were characterized as large eosinophilic or granular globes within the enlarged myelin sheaths, sometimes accompanied by moderate accumulation of microglias and/or macrophages. In contrast, such spheroid formation was minimal in the brain of CCA. In the cerebellum, mild to moderate loss of the Purkinje and granular cells were recognized in three dogs with NAD, whereas these changes were more prominent in a dog with CCA. Although the clinical signs and MRI findings relatively resembled between NAD and CCA, the histopathological features considered to be quite differ, suggesting distinct pathogenesis and etiology. Since both NAD and CCA are proposed as the autosomal recessive hereditary disorders, careful considerations might be needed for the breeding of Papillon and Chihuahua dogs.     

Early effects of ethylene glycol on the ultrastructure of the renal cortex in dogs

A sublethal dose of ethylene glycol was administered orally to 3 groups of dogs; dogs of a control group were given distilled water instead. Renal cortical biopsy samples were obtained from dogs of experimental and control groups at various times after treatment. Tissue was examined by use of light microscopy and transmission electron microscopy. In dogs of the control group, the light and electron microscopic appearances of tissue were within normal limits at all sample collection hours. In dogs of the experimental groups, renal corpuscular structure remained within normal limits by use of light and electron microscopy throughout the study, though morphologic change was seen in other structures of the cortex. Light microscopic lesions first appeared at 12 hours, and were similar to those reported in the literature. Ultrastructural lesions were first observed in the 5-hour samples, and similar to the light microscopic lesions, were most common in the proximal convoluted tubules (PCT). Initial PCT cellular changes included vacuolization of cells and distention of the parabasal extracellular spaces; PCT cellular lesions seen in later-hour samples included formation of apical buds and cellular rupture. Internalization or sloughing of the PCT brush border was not observed. Distal convoluted tubules (DCT) were frequently dilated and/or packed with cellular debris. A few DCT cells had degenerative or necrotic changes. In PCT and DCT, abnormal cells were frequently flanked by normal or nearly normal cells. During later hours, a few cells with types of changes first observed in early hours continued to be observed, implying ongoing response of cells to the toxin.     

Anatomical relationship between enkephalin-containing neurones and caecum-projecting neurones in the chicken intestinal nerve

The anatomical relationship between enkephalin-immunoreactive neurones and caecum-projecting neurones in the intestinal nerve of Remak (INR) of the chicken was investigated using retrograde transport of cholera toxin subunit B and immunohistochemistry with anti-enkephalin serum. After injection of cholera toxin into the base or body of the caecum, labelled neurones were mainly observed in the cranial part of the rectal INR. Enkephalin-immunoreactive neuronal cell bodies were found in the caudal part of the rectal INR and their fibres closely surrounded caecum-projecting neurones in the cranial part of the rectal INR. Diameters of caecum-projecting neurones surrounded with enkephalin-containing terminals were significantly larger than those of caecum- projecting neurones without enkephalin-terminals (P < 0.01). From these results, it is suggested that enkephalin-containing neurones are able to affect large-sized caecum-projecting neurones. This pathway may be involved with unique motility of the rectum and caeca that uric acid is retrogradely carried from the cloaca to the caeca.     

Functional MRI activity in the thalamus and occipital cortex of anesthetized dogs induced by monocular and binocular stimulation.

The neuroanatomy of the mammalian visual system has received considerable attention through electrophysiological study of cats and non-human primates, and through neuroimaging of humans. Canine neuroanatomy, however, has received much less attention, limiting our understanding of canine vision and visual pathways. As an early step in applying blood oxygenation level dependant (BOLD) functional magnetic resonance imaging (fMRI) for veterinary use, we compared visual activity in the thalamus and occipital cortex of anesthetized dogs presented with binocular and monocular visual stimuli. Activity in the left and right thalamus and occipital cortex during monocular stimulation was also compared. Six beagles were presented with a vertical grating visual stimulus and scanned at 4 Tesla. Each dog was scanned twice under each of 3 anesthetic protocols (isoflurane, propofol, and fentanyl/midazolam). We found: 1) significant BOLD activation in the lateral geniculate nucleus (LGN) of the thalamus and the occipital cortex; 2) a significantly larger area of activation in the LGN during monocular stimulation than during binocular stimulation; and 3) that activity in the hemisphere contralateral to the stimulus was not significantly greater than that ipsilateral to it.     

Polymerase chain reaction (PCR) amplification of parvoviral DNA from the brains of dogs and cats with cerebellar hypoplasia

Cerebellar hypoplasia in cats is caused most commonly by an in utero or perinatal infection with feline panleukopenia virus (parvovirus). Cerebellar hypoplasia has been reported infrequently in dogs, but no viral etiology has been identified to date. DNA was extracted from archival, paraffin-embedded, cerebellar tissue from 8 cats and from 2 canine littermates with cerebellar hypoplasia, 2 canine littermates with cerebellar cortical abiotrophy, 6 dogs with congenital cerebellar vermal defects, 1 dog with congenital hydranencephaly, and 15 dogs and cats with various encephalitdes. The DNA extracted from each cerebellum was subject to polymerase chain reaction (PCR) amplification by 3 primer pairs specific for parvovirus DNA. Sequence analysis of PCR products from each of the 8 cats and 2 dogs with cerebellar hypoplasia confirmed their identity with parvoviral DNA. The 6 dogs with cerebellar vermal defects, 2 dogs with cortical abiotrophy, 1 dog with congenital hydranencephaly, and all control samples were PCR negative for parvovirus. Parvoviral structural proteins were not identified by immunohistochemistry in either dog with cerebellar hypoplasia. This study shows that parvoviral DNA can be amplified from feline and canine archival brain tissue and that cerebellar hypoplasia in dogs might be associated with in utero parvovirus infection.     

Development of Purkinje cells in the ovine brain

Purkinje cells are involved in many vital functions within the body. Twenty ovine fetuses ranging from 2 to 5 months of gestation, two lambs in the first week after birth and three adult sheep were studied. Sections of the cerebellum were stained with haematoxylin and eosin, cresyl violet and Klüver-Barrera. This study indicates that Purkinje cells began to appear after the 15(th) week of gestation. There were varying degrees of development of Purkinje cells in different zones of the cerebellum. Our findings in sheep fetuses suggest that the maturation of Purkinje cells starts in the caudal regions of the cerebellum and that the process begins in the vermis before it does in the cerebellar hemispheres. The alignment of Purkinje cells was found to be very regular in the caudal regions of the cerebellum. A partial absence of Purkinje cells in the rostral regions of the cerebellum was observed in both sheep fetuses and adult sheep. In the first post-natal week, some ectopic Purkinje cells were found in the white matter of the cerebellum.