Biomedical subjects
Publications and source records attributed to A deLahunta.
Three of nine dairy calves born in the spring/summer wee severely ataxic at birth. Necropsy of the 3 affected calves revealed severe cerebellar degeneration (hypoplasia). Clinical signs were inapparent in the adult cows. Serum neutralization titers of the cows and calves indicated high bovine viral diarrhea titers.
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Six kid goats with CNS disease were studied by a variety of techniques. All had morphological evidence of Viral Leukoencephalomyelitis of Goats. (VLG) characterized by demyelinating encephalomyelitis and pneumonitis. Attempts were made to isolate a virus from 5 of these goats by direct culture of CNS and visceral tissues. Syncytial formation was found in some lung, spleen and bone marrow cultures but syncytia were found to be free of complete virus by electron microscopy. When newborn goats were inoculated with syncytia forming cells, a visna-like virus was found in bone marrow cultures of 1 goat 8 days post inoculation. Bone marrow cells from a twin goat 3 months after inoculation produced syncytia without complete virus. it is suggested that complete virus might be present in goats shortly after infection, while persisting in an incomplete form. Three of the 6 goats studied also had lesions of swayback with diffuse encephalomyelopathy and low liver copper levels. Control copper levels in kids with non-neurological disease were variable, occasionally being as low as swayback animals. The experience of others that swayback in the goat and low copper status are poorly correlated is confirmed. Discrepancies inherent in assaying formalin preserved tissues for copper are described.
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Coonhound paralysis (CHP), a polyradiculoneuritis of dogs that resembles the human Guillain-Barré syndrome, was experimentally reproduced by inoculating a dog with raccoon saliva. The test animal was a coonhound that had previously sustained two naturally occurring attacks of CHP. Success in inducing the disease strengthened the notion that raccoon saliva contains the etiologic factor for CHP and that only specifically susceptible dogs are at risk of developing CHP when exposed to this factor.
Thiamine deficiency encephalopathy occurred in a specific-pathogen-free cat colony where the diet consisted exclusively of commercially canned diet. This product was described by the manufacturer as a complete diet for cats. The clinical diagnosis was confirmed by the demonstration of bilaterally symmetrical hemorrhage and microvascular fibrinoid necrosis in the brain and low erythrocyte transketolase levels. Treatment of clinically ill cats with vitamin B complex was followed by recovery within 24 hours.
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Six kittens, three males and three females, were fed exclusively for one hundred days a commercially canned red meat tuna found to contain elevated concentrations of Mercury (Hg) and Selenium (Se). A similarly sized control group was fed for the same period a dry commercial cat food comparatively low in the concentration of these elements. At the end of the feeding trial, concentrations of Hg Se were markedly higher in blood, bone, brain, kidney, liver, muscle and spleen of the kittens fed the tuna diet as compared to the corresponding controls. No behavioral abnormalities or pathological lesions were detected in any of the kittens.
Five horses of mixed breeding and 1 zebra with symmetric tetraparesis and ataxia were studied. There were 2 females and 4 males. Signs of illness were first noticed from birth to 12 months of age. Clinical and pathologic studies were performed when the animals were 4 to 24 months old. Two of the horses were related. All of the subjects had diffuse degenerative myeloencephalopathy. The degeneration was most pronounced in thoracic segments of the spinal cord. Ventral and dorsolateral funiculi were most severely affected. Axonal swelling and abnormal neuronal cell bodies were seen in the gray matter of the spinal cord and in some brain-stem nuclei. These changes were most prominent in the nuclei of the dorsal spinocerebellar tract. The cause was not determined.
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Ten Kerry Blue terriers from a kennel in New York and 3 from a kennel in California developed clinical signs of a progressive cerebellar disorder, with its onset between 9 and 16 weeks of age. In 9 sequential necropsies, progressive cerebellar cortical degeneration, with loss of Purkinje's cells, was demonstrated. As the disease progressed, there was bilateral symmetric degeneration of the olivary nuclei followed by degeneration of the substantia nigra and caudate nucleus, bilaterally. The California and New York dogs were related, and an autosomal recessive inheritance was proposed for the disease.
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An isolated case and an outbreak of parelaphostrongylosis in goats are described. Signs included tetraparesis, hemiparesis, tetraplegia, spastic gait, scoliosis, vestibular strabismus, blindness, and death. Five cases were necropsied and nematodes were seen in the brain and spinal cord of four of these. Intact adult nematodes from two cases were identified as Parelaphostrongylus tenuis, the meningeal worm of white-tailed deer. Cerebrospinal fluid analysis from affected goats showed a moderately elevated protein content, evidence of hemorrhage, and mononuclear cell and eosinophil pleocytosis. Recoveries are recorded.
In the neoplasm of this report a final diagnosis of a circumanal gland adenocarcinoma invading the vertebral column and canal was made based on the histologic appearance. No growths were noted in the circumanal gland region and the location of the primary neoplasm is open to debate.
Spinal cord compression subsequent to radical laminectomy was investigated. A modified deep dorsal laminectomy technique was devised to allow extensive exposure and decompression of the canine spinal cord without undue hazard of postoperative fibrotic spinal cord compression. A previously described laminectomy technique was modified by the addition of spinal plating to avoid the occurrence of constrictive fibrosis.
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A post-mortem myelogram was used to diagnose a vertabral fracture in a Red-tailed Hawk (Buteo jamaicensis). This diagnosis led the authors to believe that myelography would be useful in live birds. In a pilot study using live adult female chickens (Gallus domesticus), mammalian myelographic techniques were modified for avian anatomic differences. A thoracolumbar puncture site was used rather than the lumbar or cisternal site which is commonly used in mammals. The volume of contrast medium needed to produce a diagnostic myelogram in birds (0.8-1.2 ml/kg) was found to be approximately four times that needed in mammals. A 25 gauge spinal needle was used rather than a 23 gauge needle. Myelograms of diagnostic quality were obtained with normal subject recovery. Seizures, the most common post-myelographic complication in mammals, were not observed in any of the birds studied. Avian myelography was found to be a cost effective and humane technique with potential application to avian practice.