PubMed Health⌕ Search

Biomedical subjects

S T Simpson

Publications and source records attributed to S T Simpson.

At least 19 recordsLinked to original sources
PubMed1997

Nimodipine for treatment of idiopathic epilepsy in dogs.

OBJECTIVE: To evaluate efficacy and safety of the calcium channel antagonist nimodipine in dogs with idiopathic epilepsy. DESIGN: Prospective clinical trial. ANIMALS: 10 dogs with idiopathic epilepsy. Dogs were included if seizures were inadequately controlled despite treatment with barbiturates and serum phenobarbital concentrations were > 25 micrograms/ml, if dogs had intolerable adverse effects when treated with barbiturates, or if dogs had mild, inadequately treated seizures. PROCEDURES: Dogs were treated with nimodipine (2.5 mg/kg [1.1 mg/lb] of body weight, PO, q 12 h), and other medications were slowly withdrawn. Dogs were monitored for seizure frequency and severity as well as any adverse effects to the medication. RESULTS: Few adverse effects were reported. Seizure control, however, was generally inadequate. All but 2 dogs were withdrawn from the study because of poor seizure control. Plasma nimodipine concentrations were low, with a mean peak concentration of 105.3 ng/ml. CLINICAL IMPLICATIONS: Nimodipine was not successful in controlling seizures in dogs used in this study.

Animals↗
PubMed1992

Intervertebral disc disease.

This article describes the functional anatomy of intervertebral discs and their relationship to the vertebrae and spinal cord. The pathologic events and clinical complications of intervertebral disc disease are described. A discussion of proper staging of disc disease and appropriate conservative management of degenerative disc disease is included.

Animals↗
PubMed1992

Evaluation of granulocytic ehrlichiosis in dogs of Missouri, including serologic status to Ehrlichia canis, Ehrlichia equi and Borrelia burgdorferi.

Canine granulocytic ehrlichiosis was diagnosed in 37 dogs by finding ehrlichial morulae in 0.1 to 26.2% of their blood neutrophils and eosinophils. All 37 dogs had clinical signs of arthritis or muscular stiffness. Titer to Ehrlichia canis was determined in sera from 31 of the 37 dogs; 25 dogs had titer ranging from 1:20 to 1:5,120. In the other 6 dogs, titer to E canis was less than 1:10. The most common hematologic abnormality in these dogs, other than rickettsiemia, was thrombocytopenia. Granulocytes infected with ehrlichial organisms were not found in another 10 dogs that had clinical signs of arthritis or muscular stiffness. Of these 10 dogs, 3 had titer to E canis ranging from 1:40 to 1:320. Titer in the other 7 dogs was less than 1:10. Ehrlichial morulae were not found in the granulocytes of 18 healthy dogs. Of these 18 dogs, 9 had titer to E canis ranging from 1:20 to 1:5,120. Titer in the other 9 dogs was less than 1:10 Titer to Borrelia burgdorferi was determined in dogs with granulocytic ehrlichiosis, arthritic dogs without detected rickettsiemia, and in healthy dogs. Low titer determined by 2 laboratories was considered to be nonspecific reaction in all 3 groups of dogs and, thus, did not indicate that the arthritic disorders were attributable to canine borreliosis.

Animals↗
PubMed1990

Metastatic thyroid solid-follicular carcinoma in the cervical portion of the spine of a dog.

A metastatic thyroid solid-follicular carcinoma in the cervical portion of the spine was responsible for severe tetraparesis in a dog. Myelography revealed an extradural compressive lesion dorsal and to the right of the midline of C3. Histologic examination was used to diagnose the mass as a solid-follicular thyroid carcinoma. The primary tumor was not evident on cervical palpation or radiography. A dorsal laminectomy centered over C3 was performed, and all visible tumor was removed from the spine. The owner declined any further treatment for the dog.

Adenocarcinoma↗
PubMed1989

Analysis of cat retina for dopamine, dihydroxyphenylacetic acid, 3-methoxytyramine and homovanillic acid.

Twenty retinas from 10 cats were evaluated for dopamine (DA) and its metabolites dihydroxyphenylacetic acid (DOPAC), 3-methoxytyramine (3-MT) and homovanillic acid (HVA) by high pressure liquid chromatography and electrochemical detection. Dopamine was present in all 20 retinas at a mean concentration of 3.00 +/- 0.54 ng/mg protein. Dihydroxyphenylacetic acid, 3-MT and HVA were detected in 16, 14 and 9 retinas respectively. In retinas in which these metabolites were detectable, they were present in the following mean concentrations: DOPAC, 1.07 +/- 0.21 ng/mg protein; 3-MT, 3.44 +/- 0.97 ng/mg protein and HVA, 4.54 +/- 1.05 ng/mg protein. Significantly higher concentrations of 3-MT (p = 0.0108, paired t test) and HVA (p = 0.0166, paired t test) than DOPAC were present in cat retina. Linear correlation analysis between DA and its metabolites indicated that the 3-MT and DOPAC concentrations correlated well with each other and with the amount of DA in cat retina. The concentrations of the end product metabolite, HVA, had poor correlations with the concentrations of 3-MT, DOPAC or DA. These data indicated that once DA is released in cat retina it can be metabolized to 3-MT, DOPAC and HVA.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1989

Determination of homovanillic acid, 5-hydroxyindoleacetic acid and pressure in the cerebrospinal fluid of collie dogs following administration of ivermectin.

Twelve adult Collie dogs were studied to determine the effects of ivermectin on neurotransmitter metabolites released from the brain into the cerebrospinal fluid (CSF) and on CSF pressure. Ten of the 12 Collies were given ivermectin orally at a concentration of 200 micrograms/kg body weight. Three of these 10 Collies showed clinical signs of ivermectin-induced toxicosis which progressed into a state of unresponsive recumbency in 2 dogs. Cerebrospinal fluid pressures and neurotransmitter metabolite concentrations in cisterna magna CSF were analysed 49 to 50 hours after administration of ivermectin in 6 of the 10 treated dogs, and in the 2 untreated control Collies. Cerebrospinal fluid pressures were within normal limits in all dogs. However, compared to the CSF concentrations in the 2 untreated and 3 non-reactive Collies, the 2 ivermectin-reactive Collies still in recumbency had elevated CSF concentrations of homovanillic acid (HVA), a metabolite of dopamine, and 5-hydroxyindoleacetic acid (5-HIAA), a metabolite of serotonin. These findings suggest an association between altered neurotransmission and severe ivermectin-induced neurological abnormalities. No evidence of elevated intracranial pressure was found.

Animals↗
PubMed1989

Postnatal development of the photoreceptor inner segment of the retina in dogs.

In dogs, the retina develops during the postnatal period in a manner similar to that in other animals born with closed eyelids. Photoreceptor inner segments are initially observed as a cytoplasmic bulge protruding sclerad through the external limiting membrane. Outer segment formation begins when a centriole within the inner segment attaches to the distal inner segment cell membrane. A few round mitochondria are observed within the early inner segments. As maturation proceeds, the number of mitochondria within the inner segments increases and the mitochondria elongate, orienting parallel to the long axis of the inner segment.

Animals↗
PubMed1988

Analysis of neurotransmitter metabolite concentrations in canine cerebrospinal fluid.

The concentrations of dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindole-3-acetic acid (5-HIAA) in CSF obtained from the cisterna magna of 21 nonneurologically compromised dogs were determined by high-pressure liquid chromatography and electrochemical detection. A rapid method of sample preparation, which involved single filtration through a deproteinizing membrane, was used. Canine CSF obtained in this manner contained 5.78 +/- 0.78 ng of DOPAC/ml, 72.19 +/- 4.09 ng of HVA/ml, and 29.95 +/- 1.67 ng of 5-HIAA/ml. Linear regression analysis between HVA and 5-HIAA yielded a correlation coefficient of 0.4804. The neurotransmitter index, HVA/5-HIAA, was found to be more indicative of the dopaminergic metabolite HVA than the acid metabolite of serotonin, 5-HIAA (correlation coefficient with HVA = 0.5529 vs a correlation coefficient with 5-HIAA = -0.4462). A poor relationship (correlation coefficient = -0.1715) was found to exist between the 2 dopaminergic metabolites DOPAC and HVA in the CSF.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1988

A rostrocaudal gradient for neurotransmitter metabolites and a caudorostral gradient for protein in canine cerebrospinal fluid.

Neurotransmitter metabolites (dihydroxyphenylacetic acid [DOPAC], homovanillic acid [HVA], and 5-hydroxyindoleacetic acid [5-HIAA]) in CSF of 10 healthy dogs were evaluated with reverse-phase high-pressure liquid chromatography and electrochemical detection. Neurotransmitter metabolite concentrations determined in CSF collected from the cisterna magna were compared with those values in CSF collected from the lumbar dorsal subarachnoid space. Amounts of DOPAC (P = 0.0444), HVA (P = 0.0001), and 5-HIAA (P = 0.0316) were significantly lower in lumbar spinal fluid compared with those values in the cervical spinal fluid. Metabolite concentrations in cervical and lumbar CSF were: DOPAC = 2.81 +/- 0.73 ng/ml of CSF and 1.28 +/- 0.57 ng/ml; HVA = 98.29 +/- 12.42 ng/ml and 4.68 +/- 1.61 ng/ml; and 5-HIAA = 46.29 +/- 8.17 ng/ml and 36.96 +/- 4.07 ng/ml, respectively. Cytologic evaluations of cervical and lumbar CSF revealed a similar concentration of 3 +/- 1 WBC/microliters in both fluids. A significant (P = 0.0002) difference in protein concentration between the 2 regions was observed, with 16.1 +/- 1.8 mg of protein/dl in the cervical CSF and 27.2 +/- 2.3 mg of protein/dl in the lumbar CSF. Between the cisterna magna and lumbar dorsal subarachnoid space of dogs, a rostrocaudal gradient existed for neurotransmitter metabolites, and a caudorostral gradient existed for protein.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Dysosmia caused by encephalitis in a dog.

A 1- to 2-year-old Beagle was referred for evaluation of a disorder of the sense of smell. The dog had suddenly lost the ability to find rabbits, even though it previously had won field trials. Clinical findings indicated mild encephalitis with some capability to respond to odoriferous stimuli. An unusual test of the sense of smell is described; results indicated some sense of smell, although behavioral response to the odor was inappropriate. It was suspected that canine distemper encephalitis may have been associated with the dysosmia.

Animals↗
PubMed1986

Myotonia congenita in a Chow Chow pup.

Myotonia congenita was diagnosed in a 12-week-old female Chow Chow that had hindlimb ataxia, a stiff gait, and occasional collapsing. The diagnosis was based on the history, clinical signs, electrodiagnostics, and microscopic examination of biopsied muscle specimens.

Animals↗
PubMed1985

Myotonic dystrophy-like disease in a dog.

A mature female Rhodesian Ridgeback was determined to have a progressive, degenerative myopathy associated with myotonia, dysphagia, and marked muscle wasting. Clinical findings revealed a diffuse muscular disease with percussion dimpling, dysphagia, and creatine kinase elevation. A paroxysmal atrial tachycardia was found. Electromyography revealed a diffuse myopathy with high-frequency bizarre waves, myotonic discharges especially in the masticatory, laryngeal, and pharyngeal muscles. A few positive sharp waves were found in some of the appendicular muscles. Histopathologic and histochemical stains on skeletal muscle biopsy specimens demonstrated moderate fiber-size variation, myofiber architectural changes, muscle-fiber splitting, focal necrosis and phagocytosis, high percentage of internal nuclei, and atrophy of type-2 muscle fibers. A review of myotonic myopathies in the dog is presented. The clinical, electrophysiologic, and histochemical findings are similar to those for myotonic muscular dystrophy in man.

Animals↗
PubMed1984

Reduced substance P-like immunoreactivity in hereditary sensory neuropathy of pointer dogs.

Two unrelated Pointer dogs, each from a breeding of normal parents which produced three affected pups in a litter of nine, began to bite their paws at 3 and 5 months of age. Insensitivity to painful stimuli was marked in the distal parts of the limbs and receded proximally. The affected dogs were euthanatized at 5 and 20 months because of acral mutilation and infection. Changes affecting the primary sensory neurons included: small spinal ganglia with reduced numbers of cell bodies, degeneration of unmyelinated and myelinated fibers in dorsal roots and peripheral nerves, and reduced fiber density in the dorsolateral fasciculus (dlf). Since nociceptive loss was the salient deficit in a neuropathy affecting primary sensory neurons, immunohistochemical studies focused on substance P, the undecapeptide imputed to mediate nociception at the first synapse in the spinal cord and brain. The localization and density of substance P-like (SPL) immunoreactivity was studied in three control dogs and the two Pointers by the indirect antibody peroxidase-antiperoxidase method. The spinal intumescences of the control dogs contained dense SPL-immunoreactivity in fibers of the dlf and the superficial laminae of the dorsal horn (i.e., laminae I, II, and the dorsal part of III). Immunoreactive fascicles on the lateral aspect of the dorsal horn and in the reticular process sent contributions medially to a plexiform fiber arrangement in lamina V. Medially, SPL-immunoreactive fibers were more loosely arranged in the internal third of laminae VI and VII and in lamina X.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗