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Biomedical subjects

E C Firth

Publications and source records attributed to E C Firth.

At least 91 records · Page 5Linked to original sources
PubMed1987

Pharmacokinetics and renal clearance of sulfamethazine, sulfamerazine, and sulfadiazine and their N4-acetyl and hydroxy metabolites in horses.

Plasma disposition, protein binding, urinary recovery, and renal clearance of sulfamethazine (SMZ), sulfamerazine (SMR), and sulfadiazine (SDZ) and their N4-acetyl and hydroxy derivatives were studied in 4 horses in a crossover trial. The plasma concentration-time curves of the metabolites paralleled those of the parent drug in the elimination phase. Sulfamethazine and SMR were extensively metabolized. In plasma and urine, the main metabolite of the 3 sulfonamides tested was the 5-hydroxypyrimidine derivative, which was highly glucuronidated. Difference in elimination half-life of SMZ, SMR, and SDZ could be related to difference in metabolism and renal clearance values. Metabolism speeds drug elimination, producing compounds with higher renal clearance values than those of the parent drug. Methyl substitution in the pyrimidine side chain increased hydroxylation of the parent drug, but prolonged the persistence of the sulfonamides studied in the body. The high concentration of N4-acetyl and hydroxy metabolites of SMZ and SMR in plasma and urine decreased the potential antibacterial activity of the parent drugs. Sulfadiazine was less metabolized, and microbiologically determined SDZ concentrations in plasma and urine were slightly lower than those measured by high-performance liquid chromatography.

Animals↗
PubMed1987

Cartilage thickness measurement in foals.

The talus and proximal and distal epiphysis of the humerus, radius, femur, tibia and distal metacarpus of 20 foals aged 0 to 150 days were obtained at necropsy and sawn sagittally into slabs 4 to 8 mm thick. The thickness of the cartilage (articular cartilage and unossified epiphyseal cartilage) was measured in three to five places in each slab, using a sliding calliper. In most epiphyses, the site, or sites, of thickest cartilage was constant in all foals examined. The difference between thickest and thinnest cartilage within one epiphysis was greatest in distal femora and least in distal metacarpi. The sites of most common occurrence of osteochondrosis dissecans in tali and proximal humeri concurred with the site of thickest cartilage in these bones. The most common site of equine osteochondrosis, the middle and distal thirds of the lateral trochlear ridge of femora, is not the location of thickest cartilage in this epiphysis. Haematological epiphyseal osteomyelitis in foals occurs most frequently in the areas where cartilage thickness is greatest in the medial femoral condyle, talus and distal radius.

Aging↗
PubMed1986

Effect of the injection site on the pharmacokinetics of procaine penicillin G in horses.

The plasma penicillin concentrations were determined in 5 horses given an IV injection of sodium penicillin G; plasma penicillin concentrations were also determined in a crossover experiment, where animals were given procaine penicillin G subcutaneously at 1 site and IM at 4 sites. The mean penicillin plasma peak concentration and bioavailability were highest after the drug was injected in the neck and biceps musculature. Injections in the gluteal muscle and in the subcutaneous sites resulted in similar, but lower, more persistent penicillin plasma concentrations and a lower bioavailability than were obtained with injection in the neck and biceps musculature. The pharmacokinetic data obtained after penicillin was administered via the pectoral muscle route exhibited an intermediate position. Therapeutic implications of the routes of administration with respect to hemolytic streptococcal infections are discussed.

Animals↗
PubMed1986

Thoracic limb digital extensor denervation in young horses.

Low radial neurectomy in the left thoracic limb was performed in 4 mixed-breed weanling horses, with subsequent paralysis of the lateral and common digital extensor muscles. Weight bearing of the denervated and control limbs was discouraged by the use of special shoeing. Clinical signs of flexural deformity were not induced in the horses.

Animals↗
PubMed1985

Tarsal osteomyelitis in foals.

Nine foals with haematogenous osteomyelitis of the tarsal bones were studied clinically, radiologically and pathologically. Clinical examination, including aspiration of articular or periarticular effusions in the tarsal area, and radiological study provide definitive diagnosis in most cases.

Animals↗
PubMed1984

Retained cartilage in the distal radial physis of foals.

Examination of growth plate defects in the distal radial physis of 13 foals three to 70 days of age revealed lesions in the lateral and medial aspects of the distal radial physis; the lateral defects were more numerous and obvious. Lesions consisted of widening of the zone of hypertrophying cells of the metaphyseal growth plate (retained cartilage), retained cartilage with discontinuity of cartilage and primary spongiosa, and microfracture of the primary spongiosa. In some foals, the cartilage retention was thought to be due to primary spongiosa microfracture, although fracture subsequent to cartilage abnormality was not excluded.

Animals↗
PubMed1983

Microangiographic studies of metaphyseal vessels in young foals.

Selective perfusion and microangiographic examination of the radius and metacarpus of 30 foals were performed. Vessels of extraosseous origin supplying the peripheral part of the metaphysis were not demonstrated in young foals, but became more obvious in older animals. The development of this vessel system coincided with the reduction of transphyseal vessels from the epiphysis crossing the growth plate.

Angiography↗
PubMed1983

An in vitro study on joint fitting and cartilage thickness in the radiocarpal joint of foals.

The change in the degree of fitting of the opposing articular cartilage surfaces of the radiocarpal joint of foals was studied in vitro using a pneumatic loading device. The thickness of the articular cartilage of the distal radius was examined using radiographic and histological techniques. The thickest cartilage corresponded with the approximate centre of the contact area of the opposing articular surface. The variations in articular cartilage contact area and thickness are discussed.

Animals↗
PubMed1978

Horner's syndrome in the horse: experimental induction and a case report.

The findings in 6 experimental and 1 natural case of Horner's Syndrome (HS) are presented. The experimental cases were induced by unilateral surgical section of the cervical sympathetic trunk in the middle third of the neck. The naturally occurring case was seen in a 17 year old gelding with a mediastinal tumour. The signs of HS in these horses included ptosis, miosis, enophthalmos, hemilateral sweating and temperature increase of the face and cranial cervical region on the affected side. The intensity of these signs was variable between and within animals. Miosis, enophthalmos and temperature difference were sometimes difficult to discern. Clinically the recognition of HS is important in the localization of lesions, and when accompanied by nasal haemorrhage is highly suggestive of guttural pouch mycosis.

Animals↗
PubMed1977

Vestibular disease, and its relationship to facial paralysis in the horse: a clinical study of 7 cases.

The signs observed in 6 cases of peripheral vestibular disease included incoordination, head tilt and nystagmus. The intensity of the signs varied greatly with duration of the disease, and in 3 cases facial paralysis was also present. Tympanosclerosis was demonstrable in all cases subject to radiology. Trauma was the causative factor in most cases. The causes of, and relationships between, vestibular dysfunction and concomitant facial paralysis are discussed. The exact etiology of the tympanosclerosis is unknown.

Animals↗
PubMed1977

Ischemic myelopathy caused by fibrocartilaginous emboli in a horse.

A horse that suddenly became recumbent had a focal ischemic infarct of the spinal cord between C6 and C7. The infarct was attributed to multiple fibrocartilaginous emboli. Adherence of fibrocartilaginous debris to the outer surface of the dura was interpreted as evidence that intervertebral disc degeneration and displacement of the nucleus pulposus had occurred and that the emboli arose from the disc.

Animals↗
PubMed1977

Analysis of serum proteins and cerebrospinal fluid in clinically normal horses, using agarose electrophoresis.

Using agarose as a supporting matrix, electrophoresis was conducted on 50 serum samples and 20 cerebrospinal fluid samples from clinically normal horses (n = 50) of various ages and breeds. The technique was shown to be reliable. A positive correlation between age and gamma-globulin concentration was found in young horses. Features of the electrophoretograms of serum and cerebrospinal fluid samples are discussed, and a nomenclature based on Rf values is proposed.

Age Factors↗