An evaluation of selected screening tests for bovine paratuberculosis.

The objective of this study was to evaluate the performance of the lipoarabinomannan antigen enzyme-linked immunosorbent assay (LAM-ELISA), carbohydrate antigen complement fixation (CH-CFT), and protein D antigen agar gel immunodiffusion (D-AGID) tests for bovine paratuberculosis, relative to histopathology, and to culture and isolation of Mycobacterium paratuberculosis from tissues and feces. Samples for test evaluation were collected from four sources including blood and tissues from 400 cull cows at three abattoirs in Ontario, blood and feces from a paratuberculosis survey of cattle from 120 dairy farms in Ontario, a serum bank containing samples from cattle from Ontario and Québec, and a bank of sera from cattle from Pennsylvania and the northeastern United States. The data were analyzed using receiver operator characteristic curves, estimates of relative sensitivity and specificity, and kappa statistics of agreement between tests. The LAM-ELISA performed significantly better than both the CH-CFT and the D-AGID tests. The LAM-ELISA was better at predicting fecal shedding status than tissue infection. However, the LAM-ELISA also had limitations. When interpreted as positive or negative (+/-), at a critical optical density of 0.675, its sensitivity and specificity relative to bacteriology were 49% and 87% respectively. Although the serological tests examined in this study provided some information, they did not predict well the infection status of individual animals.

An epidemiological study of paratuberculosis in dairy cattle in Ontario: study design and prevalence estimates.

An observational study involving 304 dairy herds and three abattoirs was conducted between 1986 and 1989 to investigate the epidemiology of paratuberculosis in dairy cattle in Ontario. The objectives of this paper were to describe the method of data collection for the study, to present descriptive production statistics and to present estimates of the prevalence of paratuberculosis among dairy cattle in Ontario. Mycobacterium paratuberculosis was isolated from the distal ileum and/or the ileocecal lymph node of 5.5% of 400 cull cows. Based on a lipoarabinomannan antigen enzyme-linked immunosorbent assay (LAM-ELISA) on sera, the predicted true prevalence of paratuberculosis among 14,923 dairy cattle from 304 herds, was 6.1%. Nineteen percent of 2,943 fecal cultures were uninterpretable because of overgrowth with contaminating bacteria or fungi. It was concluded that the true prevalence of paratuberculosis among dairy cattle in Ontario was no greater, and may be less than the true prevalence among dairy cattle from various regions of the United States. However, at a practical level, for the purposes of trade policy, the present study suggests that the functional prevalence is very similar in the two countries.

Colitis in calves: natural and experimental infection with a verotoxin-producing strain of Escherichia coli O111:NM.

Verotoxin-producing Escherichia coli O111:NM were isolated from two five week old Holstein calves with dysentery. On necropsy both calves had pseudomembranous ileitis, mucohemorrhagic colitis and proctitis. Large numbers of E. coli O111:NM were isolated from the colon and lesions typical of attaching-and-effacing E. coli were evident. The isolates from both calves had identical biochemical reactions and antimicrobial resistance patterns. Oral inoculation of a four day old colostrum deprived calf with 1 x 10(10) organisms of E. coli O111:NM produced a mild, focal colitis with typical attachment and effacement lesions. We conclude that the strain of E. coli O111:NM isolated from the clinical cases has the ability to produce colitis characterized by attachment and effacement of the colonic mucosa.

Extensive large colon resection in the pony. II. Digestibility studies and postmortem findings.

The nutritional implications and adaptive processes resulting from resection of 75% of the length of the large colon in ponies were investigated. Ten ponies in good physical condition were divided into two groups: six in the experimental group and four in the control group. During the sixth postoperative month, two digestibility studies were conducted, and phosphate fractional renal excretion and serum biochemical profiles were determined in both groups. The ponies (N = 10) were euthanized six months postoperatively, and gross and histopathological examinations were performed. Results of the serum biochemical profiles, phosphate fractional renal extraction and digestibility studies showed no statistically significant difference between groups except for the serum phosphate concentration. However, large colon resection was associated with hypophosphatemia in three of the six ponies and produced an overall significantly lower phosphate concentration in the experimental ponies. This hypophosphatemia suggests that some dietary modifications may be needed postoperatively in ponies or horses undergoing this surgical procedure. Postmortem examination and histopathological examination failed to demonstrate differences between groups. Adaptive mechanisms, specifically mucosal hypertrophy or hyperplasia, were not observed.

Caprine beta-Mannosidosis in Kids from an Ontario Herd.

Caprine beta-mannosidosis, a fatal inherited deficiency of the lysosomal enzyme beta-mannosidase, was diagnosed in neonatal female Nubian crossbred twin kids from a small herd near Guelph, Ontario. The kids had been tetraplegic since birth, with whole body tremors, abnormal nystagmus and an intention tremor of the head.At necropsy, the histological lesions found consisted of widespread neuronal and visceral clear cytoplasmic vacuolation. Ultrastructurally, vacuoles were limited by a single membrane, and were empty or contained a small amount of amorphous dense material.Biochemical assay of sera and tissues confirmed negligible levels of beta-mannosidase activity, consistent with those of previously reported cases of caprine beta-mannosidosis.Vacuoles seen with light and electron microscopy are presumed to be lysosomes containing stored disaccharide and trisaccharide, the end products of incomplete catabolism of the oligosaccharide component of certain glycoproteins.

Avian encephalomalacia in Barbados, West Indies: a description of spontaneous field cases with feed analyses.

The clinical, necropsy and histopathological findings in four natural outbreaks of encephalomalacia are reported. Feed analyses implicated low levels of vitamin E as the probable cause of the condition. Treatment with vitamin E has proved to be very effective. The instability of vitamin E in animal feed ingredients during long periods of shipment into the Caribbean may be important in the pathogenesis of the disease.

Avian encephalomalacia in Barbados, West Indies: a description of spontaneous field cases with feed analyses

The clinical, necropsy and histopathological findings in four natural outbreaks of encephalomalcia are reported. Feed analyses implicated low levels of vitamin E as the probable cause of the condition. Treatment with vitamin E has proved to be very effective. The instability of vitamin E in animal feed ingredients during long priods of shipment to the Caribbean may be important in the pathogenesis of the disease. (AU)

Myodegeneration and suspected selenium/vitamin E deficiency in horses.

The clinical, macroscopic, and microscopic features of 10 isolated cases of myodegeneration in foals were compared. Low values for selenium and vitamin E content were found in the hay and oats from one breeding stable. Serum selenium concentrations in mares at this stable were also low. Creatinine phosphokinase and serum glutamic oxaloacetic transaminase activities were increased in 2 young foals at this stable; in 1 of these foals, both enzymatic activities were markedly reduced after treatment with vitamin E and selenium. Nutritional myodegeneration was suggested as a diagnosis in this stable, on the basis of the histologic findings, feed analyses, serum selenium values, response to treatment, and enzymatic determinations. Nine other isolated cases of nutritional myodegeneration were tentatively diagnosed on the basis of macroscopic and microscopic findings and the young age of the animal. The gross lesions included pale areas in the myocardium and skeletal muscle masses. Histologically, lesions were characterized by fragmentation and hyaline and granular changes in swollen muscle fibers in widely distributed skeletal muscle masses.

Dietary induction of mulberry heart disease and hepatosis dietetica in pigs. I. Nutritional aspects.

Two trials were conducted, involving 48 Yorkshire specific pathogen-free pigs, three to four weeks old, to investigate diets which would result in a high incidence of deaths from mulberry heart disease and hepatosis dietetica in pigs. Diets based on ground corn with torula yeast resulted in a high incidence of death. Protein supplements of dried skim milk or soybean meal with corn did not induce a high incidence of death. Diets supplemented with torula yeast had the lowest selenium concentration and highest (alpha-)tocopherol concentration of the diets investigated and resulted in lower liver selenium concentrations. A higher frequency of hepatosis dietetica, mulberry heart disease, skeletal muscle degeneration and exudative diathesis was observed in pigs fed the low level selenium diets containing torula yeast.

Effect of supplemental vitamin E and selenium in high moisture corn diets on the incidence of mulberry heart disease and hepatosis dietetica in pigs.

Forty-eight intact male pigs were used to investigate the influence of source of protein supplement, corn moisture content, and supplemental vitamin E-selenium survived the cidence of mulberry heart disease, hepatosis dietetica and associated lesions. Pigs fed soybean meal-high moisture corn diets survived fewer days than pigs fed the other diets. None of the pigs fed torula yeast-dry corn or soybean meal-high moisture corn without supplemental vitamin E-selenium survived the 13 week trial. Supplemental vitamin E-selenium increased survival of pigs. A higher incidence of hepatosis dietetica, myocardial degeneration, skeletal muscle degeneration, and exudative diathesis was observed in pigs fed torula yeast-dry corn or soybean meal-high moisture corn than pigs fed soybean meal-dry corn. Supplemental vitamin E-selenium resulted in a reduction in the incidence of the above lesions by approximately 50% with the exception of hepatosis dietetica. Tissue selenium concentration did not appear to be related to the incidence of the various lesions.

Vitamin E, selenium and methionine supplementation of dystrophogenic diets for pigs.

Forty-eight weanling S.P.F. Yorshire pigs were used to study the influence of supplemental vitamin E (25 IU per kg of diet) selenium (0.5 ppm in diet) and methionine (0.1% in diet) on the incidence of hepatosis dietetica and mulberry heart disease when fed a torula yeast-corn diet. Vitamin E and/or selenium increased pig survival. Supplemental selenium resulted in increased liver selenium concentrations. No hepatosis dietetica was observed in any of the pigs. The addition of vitamin E and/or selenium at the levels used did not reduce the frequency of myocardial lesions; however, they prevented skeletal muscular dystrophy and exudative diathesis. The myocardial lesions were less severe in supplemented pigs compared with unsupplemented controls.