Roger Clemmons

• DVM, PhD
• Neurologist at Veterinary Specialty Hospital of Palm Beach Gardens, Palm Beach Gardens, Florida, United States

Levetiracetam is used to manage status epilepticus (SE) and cluster seizures (CS) in humans. The drug might be absorbed after rectal administration and could offer a practical adjunct to rectal administration of diazepam in managing SE and CS. Levetiracetam is rapidly absorbed after rectal administration in dogs and maintains target serum concentra...

Monitoring phenobarbital levels in dogs has not traditionally taken free-to-bound serum phenobarbital levels into consideration. This study was designed to evaluate free-to-bound phenobarbital in healthy research dogs during the initiation of therapy with phenobarbital. These findings were compared with the levels obtained during routine therapeuti...

A 13 mo old spayed female mixed-breed dog presented in a nonambulatory state that was attributed to severe myoclonus secondary to distemper. The authors hypothesized that mitigating the myoclonus would help the dog become ambulatory and expedite convalescence. They injected the severely affected muscles with botulinum toxin on two separate occasion...

A prospective study to determine if low-level laser therapy and surgery for intervertebral disk herniation encourage ambulation faster than surgery alone. Thirty-six dogs with acute paraparesis/paraplegia due to acute intervertebral disk herniation were evaluated and given a modified Frankel score. Dogs with scores 0 to 3 were included in the study...

To evaluate whether canine bone marrow stromal cells (BMSCs) can migrate and adopt neural phenotypes in the developing mouse brain we transplanted fluorescently labeled BMSCs into the lateral ventricle of immunocompromised neonatal mice. Most fibroblasts, used as a control, and BMSCs isolated from adult dogs remained around the injection site and e...

The present in vitro study was designed to evaluate whether canine bone marrow stromal cells (BMSCs) promote neurite outgrowth from dorsal root ganglion (DRG) neurons. Bone marrow aspirates were collected from iliac crests of three young adult dogs. DRG neurons were cultured on BMSCs, fibroblasts, or laminin substrates. DRG neurons were also cultur...

Bone marrow stromal cells (BMSCs) have gained considerable attention as a potential source for cell transplantation therapies for a variety of diseases due to their accessibility, proliferative capacity, and multilineage differentiation properties. Canine BMSCs have been shown to contribute to regeneration of osseous tissues, but knowledge about th...

Detection of intrathecal IgG synthesis is important in evaluating inflammatory diseases in the central nervous system. Isoelectric focusing (IEF) is currently the most sensitive method to demonstrate intrathecal IgG synthesis and may have diagnostic value for German Shepherd degenerative myelopathy (GSDM). The objective of this study was to adapt a...

Bone marrow stromal cells (BMSCs) isolated from humans and rodents have been shown to generate neural cells under specific culture conditions and after transplantation in the central nervous system. The apparent plasticity of BMSCs has therefore been a target of intensive research in attempt to develop a novel therapy for neurological diseases. Can...

Analysis of cerebrospinal fluid (CSF) is part of a routine clinical workup in veterinary patients when neurologic disease is suspected. However, knowledge of particular protein markers of disease in CSF is limited. The concentration of myelin basic protein (MBP) in CSF is used as a biochemical marker in humans to evaluate demyelinating lesions in t...

An 11-year-old, spayed female giant schnauzer was presented for evaluation of chronic, progressive tetraparesis. Diagnostic imaging was consistent with intervertebral disk protrusion, and surgical decompression and stabilization were performed. Postoperatively the dog did not improve, and further imaging suggested an intramedullary mass at the leve...

Chondrocytes isolated from proximal femoral articular cartilage from 3 adult cat cadavers were expanded in monolayer culture and subsequently cultured in alginate microspheres for 24 days. Cell proliferation and production of proteoglycans in alginate microspheres were observed during day 18 and 24. Quantification of chondroitin sulfates (CS) by ca...

To evaluate cell surface markers of bone marrow-derived canine mesenchymal stem cells (MSCs) by use of flow cytometric analysis and determine whether canine MSCs express proteins specific to neuronal and glial cells. Bone marrow aspirates collected from iliac crests of 5 cadavers of young adult dogs. Flow cytometric analysis was performed to evalua...

Magnetic resonance imaging (MRI) is a non-invasive technique widely used to investigate degenerative joint disease (DJD). In this study, we obtained magnetic resonance images of feline hip joints, using a high magnetic field MRI unit (4.7 tesla) with proton density (PD)-weighted and T2-weighted fast spin-echo (FSE). PD-weighted FSE provided detaile...

To investigate temporal dynamic changes in the synthesis of chondroitin 6-sulfate (CS6) and chondroitin 4-sulfate (CS4) in vitro, normal articular cartilage of femoral heads was harvested from three dogs. Chondrocytes were isolated and cultured in alginate microspheres for 21 days. On days 7, 14 and 21, DNA content was quantified by fluorometric as...

From December, 1997, through November, 2000, 306 deaths were documented among adult and subadult American alligators (Alligator mississippiensis) of Lake Griffin, Florida (USA). Some live alligators were lethargic and unresponsive to approach. To determine the cause, we examined ten alligators captured from Lake Griffin between December 1997 and Ju...

Two domestic shorthair cats presented for clinical signs related to multifocal central nervous system dysfunction. Both cats had signs of vestibular system involvement and anisocoria, and one had generalized seizure activity. Cerebrospinal fluid analysis revealed a neutrophilic pleocytosis with protein elevation in one cat and pyogranulomatous infl...

A 3-year-old neutered female mixed breed dog as examined because of severe, generalized seizure activity, tetraparesis, and encepha-lopathic signs. Cerebrospinal fluid (CSF) evaluation was unremarkable except for a mild increase in protein. Serum and CSF titers for infectious diseases were negative. Magnetic resonance (MR) imaging examination of th...

Chondroitin sulfate (CS) isomers, 6-sulfate (CS6) and 4-sulfate (CS4), change their ratio to each other in cartilaginous tissues with aging. In this study, a quantitative measurement method of CS6 and CS4 was developed, using capillary electrophoresis (CE). Various buffer solutions, pH, and digestion times were studied, and the use of 0.1 M Tris-HC...

A 7-month-old, neutered female Labrador Retriever was evaluated for tetraparesis and subtle cerebellar dysfunction. Clinical signs progressed over a period of 6 weeks to severe ataxia, hypermetria, intention tremors, and finally non-ambulatory tetraparesis. On magnetic resonance imaging of the brain there were large, bilaterally symmetrical, ovoid...

Vertebral physitis with bone sequestration and a portosystemic shunt were diagnosed in an 18-month-old female Pekingese dog. The latter was determined by the presence of low blood urea nitrogen, elevated serum bile acids, microhepatica and an increased portosystemic shunt fraction. It was managed with a home-cooked low protein diet. Vertebral physi...

A 7-year-old intact male pitbull presented with a 2-month history of progressive dysequilibrium. Cerebrospinal fluid analysis was indicative of a central inflammatory or neoplastic disorder. A cerebellar cystic structure was identified on magnetic resonance imaging which was found to be an epidermoid cyst on histopathology.

An 11-month-old, neutered female miniature schnauzer presented with a severe head injury. The dog was treated for the acute effects of craniocerebral trauma and was hospitalized for just over a week. Several weeks later, she became weak and lethargic. A diagnosis of hypoadrenocorticism was confirmed with an adrenocorticotropin hormone (ACTH) stimul...

Unconventional or alternative therapies have gained popularity with the general public and they are seeking these treatments and preventative procedures for their animals. The National Institutes of Health currently has a division of alternative medicine research. Veterinarians have formed special-interest groups for several different treatments an...

Pheochromocytomas are uncommon tumors arising from the adrenal gland, which have potential for aggressive local spread. The diagnosis is extremely challenging, particularly when classical endocrine signs are absent. This paper presents two canine cases of pheochromocytoma in the vertebral canal and illustrates the potential for detection of the tum...

The effects of a single intramuscular administration of polysulfated glycosaminoglycan (PSGAG, Adequan®a) on activated partial thromboplastin time (APTT), prothrombin time (PT), complete blood count (CBC), biochemical profile and urinalysis were determined in six adult cats. An injection of 5 mg/kg of PSGAG was given to three of the cats, and an in...

DM in the German Shepherd is an immune-related disorder whose clinical signs are explained by a widespread degeneration of the white matter pathways in the thoracolumbar spinal cord. Therapy includes exercise, vitamin supplementation, and EACA medication. Avoiding unnecessary surgical procedures is also important to preclude permanent deterioration...

Five cats were treated with an azathioprine suspension (2.2 mg/kg of body weight on alternate days) and 2 cats were given vehicle (controls) for 9 weeks. Complete blood and platelet counts and serum biochemistry variables were monitored weekly. Bone marrow aspirates were evaluated every 3 weeks, and core bone marrow biopsy was performed at the end...

Following previous studies in rats, the ability of two chemical delivery systems (CDSs) to deliver benzyl penicillin (1) to the central nervous system of rabbits and dogs was investigated. One of the systems (3) was a diester of methylene diol, and the other (5) a diester of ethylene 1,2-diol; in both, one hydroxyl group of the diol was esterified...

The pharmacokinetics of a dihydropyridine-pyridinium salt-type chemical delivery system (CDS) for brain-targeted delivery of estradiol (E2) were examined in dogs. Parameters evaluated in vitro included stability in buffers and biological fluids and plasma protein binding. In vivo studies examined drug and metabolite concentrations in plasma, urine,...

Plasma and erythrocyte cholinesterase activities were determined for 40 free-living and 12 captive common long-nosed armadillos (Dasypus novemcinctus) in order to establish normal values for monitoring pesticide exposure. Plasma cholinesterase activity ranged from 105 to 549 U/liter with no sexual or seasonal differences. Plasma values from captive...

Using an autogenous bone graft (obtained from the iliac crest), 4-mm cancellous bone screws, and polymethylmethacrylate, a distracted cervical spinal fusion technique was performed on 10 dogs with myelographic evidence of caudal cervical spondylomyelopathy. All dogs had evidence of dynamic soft tissue spinal cord compression, as indicated by flexio...

An anorectic, adult West African dwarf crocodile was examined because of bilateral hind limb paresis. Clinical findings included multiple skin wounds, osteomyelitis of the distal portions of the right radius and ulna, severe anemia, and Serratia marcescens bacteremia. The crocodile died after a blood transfusion. At necropsy, hemorrhage in the suba...

A severe and progressive neuromuscular disorder accompanied by clinical, electrophysiological, and pathological features resembling human dystrophia myotonica was observed in three foals. This disorder was apparent as early as 1 month of age and involved progressive skeletal muscle dysfunction, initially characterized by proximal muscle hypertrophy...

A 2-year-old Boston Terrier was referred because of depression and hindlimb and tail paresis. Clinical examination and serum biochemical analysis resulted in a diagnosis of encephalomyelitis and myositis. Results of testing for Dirofilaria immitis were positive. Gross and histologic examination revealed an aberrant adult heartworm infection resulti...

An interaction between blood platelets and adult heartworms was examined in vitro. Surfaces of glutaraldehyde-fixed heartworms, which were taken from infected dogs washed, and incubated in platelet-rich plasma (PRP), were evaluated by scanning electron microscopy. Adherence of platelets to heartworms occurred only with PRP from infected dogs. Aggre...

The arachidonate pathway of canine platelets was assessed in dogs of varying ages by examination of platelet aggregation to arachidonic acid and by measurement of arachidonic acid-induced platelet malondialdehyde production. As age increased, arachidonic acid-induced platelet aggregation showed a progressive prolongation in the lag phase before agg...

Ovariectomized Long-Evans rats received bilateral rostral hypothalamic infusions of 5,7-dihydroxytryptamine (5,7-DHT). Neurochemical determination of catecholamines (CA) and indoleamines in the hippocampus, hypothalamus and mesencephalon revealed that 5,7-DHT infusions had no effect on CA content in these areas nor in mesencephalic serotonin or 5-h...

Superoxide dismutase (SOD), a free radical scavenger with anti-inflammatory activity, was administered IM to horses. Ex vivo platelet aggregation in response to arachidonic acid was monitored to determine whether exogenous SOD altered equine platelet prostaglandin metabolism. Preparations of platelet-rich plasma obtained before SOD administration w...

Dogs exposed to topical organophosphate (fenthion) developed decreased plasma and muscle cholinesterase activities. After 2 doses were applied (1 week between doses), plasma concentrations declined 80% and muscle cholinesterase activity was reduced by 56%. Decremental responses to repetitive nerve stimulation developed after fenthion administration...

Whole blood platelet counts, coagulation profiles and in vitro platelet function tests were monitored in newborn foals during the first week of life. Platelet counts, mean platelet volumes and thrombin-induced malondialdehyde production were not different from adult mares. Prothrombin and partial thromboplastin times were slightly, but not signific...

A method for obtaining reliable blood platelet yields in canine platelet-rich plasma, using increased sodium citrate concentration, is presented. Maintaining a quiet environment or anesthetizing the animals with thiamylal sodium aids in collection of platelets. Aggregation of platelets from 60 dogs of various breeds in response to arachidonic acid,...

The effects of centrifugation force and time upon platelets function, mean platelet volume and platelet yield were compared with whole blood platelet counts and size in citrated blood samples from the bovine, canine, caprine, equine, feline, ovine and porcine species. The results were similar, for a given species, irregardless of sample volume. Bov...

A 5-year-old dog developed neurologic signs of thoracolumbar spinal cord dysfunction. The presence of an epidural mass which affected the electromyogram of the T-13 to L-3 spinal segments was demonstrated by myelography. Surgical removal was attempted. Examination of frozen and formalin-fixed tissues revealed the mass to be a chondrosarcoma. Doxoru...

The action of epinephrine (E) on canine platelet aggregation is described. Although E did not induce a change in platelet shape or aggregation, potentiation of aggregation induced by the following agents was observed at physiological E concentrations (that is, less than 10 nM/1): arachidonic acid; the dense granule agonists, ADP and serotonin (5-HT...

A neurochemical evaluation of beagle dogs with naturally occurring spontaneous generalized convulsive seizures was performed. Amino acid profiles of serum, cerebrospinal fluid (CSF), and biopsied cerebral cortex from epileptic dogs were compared with those from seizure-free siblings. No differences in absolute levels were noted. However, when level...

The arachidonate pathway of human, feline, canine, equine, mink, porcine, and bovine platelets was evaluated by determining the formation of arachidonate-induced malondialdehyde (MDA), thrombin-induced MDA and thrombin-induced thromboxane (Tx) B2. In addition, arachidonate-induced platelet aggregation responses were monitored. Arachidonate activate...

A medullary carcinoma of the thyroid in a dog first became evident because of a distant metastasis. The histologic characteristics of the tumor differ from those previously reported in dogs in that this tumor was highly malignant; anaplasia and mitotic figures were common. The diagnosis was substantiated by radioimmunoassay for calcitonin. Serotoni...

Progressive myelopathy is a spontaneous disease that occurs in older German shepherd dogs. The clinical signs of the disease progress from loss of proprioceptive function to severe posterior ataxia. Pathologic findings include demyelination and axonal degeneration in the spinal cord. Data presented here indicate a marked impairment in the prolifera...

Progressive myelopathy in the German shepherd dog is a degenerative neurologic disease of unknown etiology. Results presented in a previous study indicated a depression in the response to thymus-dependent mitogens by peripheral blood leukocytes obtained from dogs with progressive myelopathy. Data presented here indicate that this depressed response...

Regional concentrations of tryptophan, serotonin (5HT), 5-hydroxyindoleacetic acid (5HIAA), norepinephrine, and dopamine were determined in the ovine brain. Tryptophan concentrations varied between 18.6 nmoles/g of tissue (hypothalamus, midbrain) and 26.9 nmoles/g (cerebellum). The 5HT concentrations varied 0.34 nmoles/g (cerebellum) and 3.75 nmole...