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Biomedical subjects

A D Watson

Publications and source records attributed to A D Watson.

At least 109 records · Page 6Linked to original sources
PubMed1987

Pharmacokinetics of three sulphonamides in ruminant and preruminant kids.

The pharmacokinetic properties of three sulphonamides were determined in ruminant and preruminant kids after oral and intravenous administration. First, sulphisomidine (SIM, 50 mg kg-1) and sulphadoxine (SDX, 30 mg kg-1) were given to seven kids, 10 to 12 weeks old, while on a milk replacer diet and again at 15 to 18 weeks when fed roughage. Secondly, SIM (100 mg kg-1) and sulphadimidine (SDD, 100 mg kg-1) were given at six to nine, 12 to 15 and 18 to 21 weeks old to eight kids, of which four were fed milk replacer and four were with their mothers (with access to roughage) until 15 weeks, after which all were fed roughage only. SDX and SDD exhibited non-linear (or capacity limited) absorption after oral dosage, suggesting possible active absorption mechanisms, and both drugs also showed non-linear elimination. Intravenous curves for SDD and SIM indicated that recycling occurred. With SDX, ruminant kids showed poorer systemic availability after oral dosage, shorter t1/2(el) and higher B than did preruminants. For SDD, ruminant kids had lower Vd and higher B than preruminants. SIM's t1/2(el) tended to shorten and beta to increase in both groups throughout the experiment. Not all differences between ruminants and preruminants in sulphonamide pharmacokinetics could be explained by the accumulation of acidic forestomach contents and the change of urine pH from acid to alkaline in the maturing ruminant. Other potential contributing factors require investigation, including possible alterations in hepatic drug metabolism. Of the three drugs tested, SDX might be the most satisfactory for therapeutic use in preruminant animals, because it has good bioavailability after oral administration and long t1/2(el).

Absorption↗
PubMed1986

Distal renal tubular acidosis in a cat with pyelonephritis.

A four-year-old castrated male domestic shorthair cat with recent onset of lethargy and depression was found to have hypokalaemia, low plasma bicarbonate concentration and a urine pH of 7. Subsequent findings of hyperchloraemic metabolic acidosis with failure to produce acid urine led to a diagnosis of distal renal tubular acidosis. Pyelonephritis associated with Escherichia coli infection of the urinary tract was also diagnosed. The urinary tract infection was eliminated by antibiotic treatment. For two years subsequently, the clinical effects of distal renal tubular acidosis have been controlled by oral administration of potassium bicarbonate, although some biochemical abnormalities have persisted.

Acidosis, Renal Tubular↗
PubMed1986

Effect of ingesta on systemic availability of penicillins administered orally in dogs.

Six penicillin preparations were administered to six dogs of various types, both when the dogs were fasted and when fed a standard meal immediately before dosing. The preparations used were: amoxycillin tablets and drops, ampicillin tablets, penicillin V tablets, phenethicillin tablets and cloxacillin capsules. A Latin square design was employed with ampicillin and the two amoxycillin preparations, while three separate cross-over studies were done with penicillin V, phenethicillin and cloxacillin. Dose rates used were 50 mg/kg for cloxacillin, and 10 mg/kg for the others. A microbiological method was used to assay penicillin in blood samples taken at intervals after dosing. Values for peak plasma drug concentration (Cmax), the time at which it occurred (Tmax), and area under the curve (AUC) were obtained for each curve of drug concentration plotted against time. In fasted dogs, ampicillin showed poorer systemic availability than did amoxycillin, with Cmax and AUC values of less than half those of amoxycillin. The solid and liquid preparations of amoxycillin had similar bioavailability. Ingesta adversely affected the systemic availability of antibiotic from all preparations tested. With ampicillin and both amoxycillin preparations, there were reduced Cmax and AUC and prolonged Tmax, indicating slowed and diminished absorption. Feeding did not alter Tmax with the other drugs, but reduced the Cmax of penicillin V, phenethicillin and cloxacillin and the AUC of cloxacillin. It is suggested that, if minimal impairment of bioavailability by ingesta is desired, then the penicillins commonly administered by mouth (amoxycillin, ampicillin, penicillin V, phenethicillin, cloxacillin) should be given to dogs that are fasting.

Administration, Oral↗
PubMed1985

Glucose intolerance in cats given short-term therapies of prednisolone and megestrol acetate.

Six cats were each given prednisolone (2 mg/kg of body weight/day) and megestrol acetate (5 mg/cat/day) on separate occasions for 8 days. The drugs induced similar increases in fasting blood glucose concentrations and decreases in glucose excretion rates in the cats. Usually, each cat developed reduced tolerance of an IV glucose load; concomitant fasting hyperglycemia occurred in 3 cats after prednisolone therapy, and in 1 of these 3 cats after megestrol acetate.

Animals↗
PubMed1984

Primary polycythaemia in a dog.

A 7-year-old, crossbred, desexed bitch had a fluctuating illness of more than 6 months duration, with signs of inappetence, reduced exercise tolerance, restlessness, panting, black diarrhoea, and red eyes and ears. Haematological examination disclosed persistent polycythaemia, reticulocytosis, normoblastaemia , and normal total plasma protein concentration when not dehydrated. Splenomegaly was present, but there was no evidence of significant pulmonary, cardiac or renal disease on physical, radiographic or electrocardiographic examination. Further investigations revealed normal arterial Po2 and oxygen saturation, and increased total erythrocyte volume. Primary polycythaemia was diagnosed. The dog was rendered anaemic by bleeding, then treated with a single injection of radioactive phosphorus. The patient has had no recurrence of signs and remains well 50 months later.

Animals↗
PubMed1983

Sporozoa in dogs and cats.

Faecal samples from 110 dogs and 71 cats were examined for sporozoan parasites by flotation. Isospora spp were present in 5.5% dogs and 4.2% cats; Sarcocystis spp in 20.9% dogs and 1.4% cats. 74.5% dogs and 77.5% cats were fed raw meat from various sources; beef was fed most often. Animals fed raw meat were more frequently infected with protozoa. No Toxoplasma oocysts were found. The results are compared with those from other surveys in Australia and New Zealand.

Animals↗
PubMed1983

Copper storage disease with intravascular haemolysis in a Bedlington terrier.

A 5-year-old male Bedlington terrier was found to have haemoglobinuria from intravascular haemolysis. The owners reported also recent vomiting, occasional diarrhoea, reduced activity and increased drinking and urination. A diagnosis of inherited copper storage disease, as previously described in this breed, was established by demonstrating characteristic light and electron microscopic changes and copper content of 7, 717 micrograms/g in biopsied liver. Treatment by chelation with d-penicillamine and a low copper diet was instituted and the dog remains well 10 months later. Intravascular haemolysis is rare in dogs and an uncommon finding in Bedlington terriers with copper storage disease.

Animals↗
PubMed1983

Idiopathic neurogenic diabetes insipidus in a cat.

A 5-year-old, domestic long-haired cat was presented for examination because of polydipsia, polyuria and inappropriate urination of 3 months' duration. Neurogenic diabetes insipidus was diagnosed, based on hyposthenuria with failure to concentrate urine in response to water deprivation and positive response to antidiuretic hormone administration. Treatment with hydrochlorothiazide or chlorpropamide orally gave inadequate antidiuresis, but response to injections of vasopressin tannate in oil was sufficient for satisfactory management.

Administration, Oral↗
PubMed1982

Double intussusception followed by reintussusception in a kitten.

A three-month-old Burmese kitten with diarrhoea developed a double intussusception, with invagination of jejunoileal intussusception into the colon. During surgical repair, about 20 cm of terminal jejunum and ileum were resected and an anastomosis performed 2 cm proximal to the ileocolic valve. A jejunoileocolic intussusception developed three days later and was reduced manually at laparatomy. The cat has grown normally since than and at one year old shows no signs of intestinal dysfunction.

Animals↗
PubMed1982

Functioning adrenocortical tumour in a dog.

Naturally-occurring hyperadrenocorticism was diagnosed in an 11-year-old female Dachshund with signs of polydipsia, polyuria, pendulous abdomen, weakness, depression and lethargy, and laboratory test abnormalities comprising lymphocytopaenia, eosinopaenia, hypercholesterolaemia and increased plasma alkaline phosphatase concentration. While awaiting hormonal test results, an adrenocorticolytic drug (o,p'-DDD) was administered for 14 days, during which the patient deteriorated. Hormonal assays suggested a functioning adrenocortical tumour, but the poor condition of the patient precluded adrenalectomy. An adrenocortical carcinoma with hepatic metastases was found at necropsy.

Adrenal Cortex Neoplasms↗
PubMed1982

Pyruvate kinase deficiency anaemia in a Basenji dog.

Pyruvate kinase deficiency anaemia was suspected in an 18-month-old male Basenji dog after other known causes of canine haemolytic anaemia had been excluded. Anaemia of moderate severity (packed cell volumes 0.20 to 0.26 1/1) and reticulocytosis (uncorrected reticulocyte counts 8 to 43%) persisted during 5 months' observation, and biopsies showed development of bone marrow fibrosis and sclerosis. The diagnosis of pyruvate kinase deficiency anaemia was presumptive because erythrocyte pyruvate kinase concentrations in the affected dog were inconclusive and related animals were not available for enzyme assay. However, the gene for pyruvate kinase deficiency is known to occur among Basenji dogs in Australia.

Anemia, Hemolytic, Congenital↗