Biomedical subjects
Publications and source records attributed to A S Nash.
During a period of seven months in 1982-83 cases of postvaccinal encephalitis were recorded in dogs in various parts of Britain after the administration of a particular batch of combined distemper/hepatitis vaccine. Detailed investigations of one of these cases revealed that the distemper component was responsible and the vaccine virus was recovered from the brain of an affected dog.
Haemobartonella felis infection was demonstrated in 38 cats which could be divided into four groups as follows: group A, feline leukaemia virus (FeLV) free cats with H felis infection alone; group B, FeLV free cats with H felis infection and other clinical conditions; group C, FeLV positive cats with H felis infection but no clinical manifestation of FeLV related or any other intercurrent disease; and group D, FeLV positive cats with H felis infection and clinical manifestations of FeLV related or other diseases. Cats in group A were healthy carriers of the infection and none was anaemic, whereas some in group B had clinical haemobartonellosis and anaemia. This anaemia was mainly mild, normocytic and normochromic. Most of the cats in group C and all in group D were more severely ill and anaemic, the anaemia usually being macrocytic and hypochromic. Splenomegaly occurred only in groups C and D. Treatment with tetracyclines did not eliminate H felis from any of the cats and blood transfusions were ineffective in promoting long term recovery from anaemia in cats with intercurrent H felis and FeLV infections. The findings in the cats in groups C and D were further compared with those in a fifth group of cats which were infected with FeLV but free of H felis.
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Over a five year period 31 dogs were diagnosed as having advanced gastric carcinoma. The most frequent clinical features were vomiting, polydipsia and weight loss. A predisposition to the tumour was found in the rough collie and Staffordshire bull terrier. In 18 dogs the main finding endoscopically was a large deep ulcer with thickened, irregular rims and walls. Fluoroscopically a marked irregularity of the mucosal surface was noted in 10 dogs. Pathologically, large ulcers with thickening of the stomach wall and involvement of the serosal lymphatics were evident in 17 dogs, and similar ulcers with involvement of the gastric lymph nodes were evident in 18 dogs.
A comparison of the relative efficiency of acridine orange with some Romanowsky staining procedures indicated that acridine orange is superior in demonstrating the presence of Haemobartonella felis in feline blood. Of the Romanowsky staining procedures, that of May-Grunwald-Giemsa was at least one and a half and about twice as efficient as the Giemsa and Leishman methods, respectively.
A survey of 155 cats for Haemobartonella felis infection in the Glasgow area revealed a prevalence of 23.2 per cent. The infection occurred in all age groups and there was no significant difference between sex or breed type. Infection with H felis was more prevalent among cats with fleas and those with feline leukaemia virus infection than among the other cats in the sample. H felis organisms identified were mainly coccoid with diameters between 0.63 micron and 1.73 micron. Rod forms, found in two cats, had lengths ranging from 0.79 micron to 1.1 micron and diameters between 0.17 micron and 0.24 micron.
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Three healthy cats were subjected to percutaneous renal biopsy of the left kidney on three occasions at monthly intervals. Three other cats were subjected to three consecutive biopsy attempts on one occasion using the left kidney. Thereafter the six cats were monitored clinically and by means of laboratory analyses of blood and urine until euthanasia four weeks after the last biopsy. Cautious insertion of the biopsy needle in an attempt to avoid over penetration of the kidney resulted in failure to obtain renal tissue on six occasions but in all 12 specimens which did contain renal tissue, glomeruli were present. Major blood vessels were present in two biopsy specimens. At necropsy, radiographic and histological studies demonstrated renal parenchymal and vascular changes in the biopsied kidneys which were similar to but less severe than those produced by a single biopsy attempt. This confirmed that avoidance of damage to major renal vessels is important and suggested that, with care, repeated biopsies need be no more harmful to the kidney than a single biopsy.
A disposable biopsy needle was modified to reduce the length of the obturator tip and specimen notch. The modified needle was then used to take renal biopsy specimens at four sites from each kidney in four cats. Twenty-nine samples of renal tissue were obtained and the average numbers of glomeruli per specimen length compared favourably with similar studies using the standard needle.
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Eight 16-week-old dogs were used to induce immune complex glomerulonephritis by daily intravenous injections of 120 mg highly cationized bovine serum albumin (pI9.5). Of four control dogs, two received unmodified native anionic bovine serum albumin (pI 4.5) while the other two received only phosphate buffered saline. The renal glomeruli were examined by light, electron (transmission and scanning) and immunofluorescence microscopy at intervals from five to 11 weeks after the start of the injections. Animals receiving cationic antigen all developed generalised diffuse granular deposits of IgG and C3 along the capillary walls; these were detected as early as five weeks and continued until the termination of the experiment at 11 weeks. Ultrastructural studies revealed many electron dense deposits along the subepithelial regions of the glomerular basement membrane. The experimental disease resembled in many respects naturally occurring membranous nephropathy, the most common form of immune complex glomerulonephritis in dogs.
A young kitten was presented with regurgitation of food at weaning. Episodes of respiratory distress and cyanosis were also present. The cause of food regurgitation was a perioesophageal vascular ring caused by left descending aorta and a right ligamentum arteriosum. This type of vascular ring has not previously been described. There was also anomalous development of the right subclavian artery and a large ventricular septal defect. The respiratory distress and cyanosis was most probably caused by a combination of tracheal compression by the vascular ring and a polycythaemia associated with the ventricular septal defect. Surgical correction was not attempted.
Eighteen dogs were given repeated doses (between 4 and 19) of ampicillin (7 mg per kg intramuscularly on 3 days a week). Fifteen of the dogs developed a subclinical glomerulonephropathy characterized by mesangial hypercellularity. While only 9 of the 18 dogs showed electron-dense deposits in the mesangium, 14 dogs had glomerular deposits of IgG and 11 of these had C3 deposits also.
Membranous nephropathy was diagnosed in two sibling cats from the same household. Both cases presented with the nephrotic syndrome but 33 months elapsed before the second cat became ill, by which time the first cat had been in full clinical remission for over a year.
The isoenzymes of canine alkaline phosphatase have been separated by isoelectric focusing on agarose gels. Alkaline phosphatase from normal tissue extracts gave heterogeneous focusing patterns with the following isoelectric points: liver pH 4.3, bone pH 4.0 to 4.9, kidney pH 4.4 to 4.7 and intestine pH 3.6 to 4.6. Plasma alkaline phosphatase isoenzymes were examined in 123 dogs with activities at least twice the normal maximum. The isoenzymes from these plasma samples had multiple bands at pH 4.3 to 4.6 but in 67 per cent of all cases, the predominant isoenzyme, named isoenzyme A, was a single band of isoelectric point pH 3.5. Isoenzyme A occurred in all dogs with diabetes mellitus or Cushing's syndrome and in 93 per cent of animals receiving steroid therapy. Increased activities of the pH 4.3 to 4.6 isoenzymes were more likely to occur in cases of hepatic degeneration.