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Biomedical subjects

N D Sargison

Publications and source records attributed to N D Sargison.

At least 37 records · Page 2Linked to original sources
PubMed2000

Campylobacter fetus fetus abortions in vaccinated ewes.

AIMS: To investigate the cause of an outbreak of ovine abortion in 1996 in a flock of 300 two-tooth (rising 2-year-old) ewes vaccinated against Campylobacter fetus fetus infection and to subsequently characterise the strain of C. fetus fetus isolated from aborted foetuses. METHODS: Standard bacteriological methods were used to identify C. fetus fetus isolates which were then antigenically typed and subjected to pulsed-field gel electrophoresis (PFGE) and compared to the vaccine strain. RESULTS: C. fetus fetus was identified as the causal agent of the abortions despite the ewes having been vaccinated before ram introduction and at the time of ram removal. Four isolates cultured from aborted material were indistinguishable when compared using antigenic typing and PFGE, but all differed from the vaccine strain. CONCLUSIONS: Within the limitations of the available typing systems, it is proposed that PFGE may be a useful tool to establish the distribution and strain variation of C. fetus fetus. CLINICAL RELEVANCE: This field case indicates the need for further study of non-vaccine C. fetus fetus strains which cause abortion in vaccinated ewes, and of the importance of these strains to the New Zealand sheep industry.

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PubMed1999

A lower motor neuron disease in newborn Romney lambs.

AIM: To determine the cause and nature of a disease in newborn New Zealand Romney lambs characterised by progressive weakness and premature death. METHODS: Affected lambs were examined clinically, humanely killed and submitted to necropsy. Selected fonmalin-fixed tissues were examined histologically. Data on the parentage of the lambs were collected. RESULTS: The principle lesions found were degeneration and loss of neurons in ventral horns of the spinal cord and brain stem and Wallerian degeneration of motor nerves and denervation atrophy of skeletal muscles fibres. CONCLUSION: The lesions are those of a lower motor neuron disease which appeared to have a genetic cause.

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PubMed1998

Evaluation of recombinant bovine somatotropin in the treatment of ovine pregnancy toxaemia.

Forty multigravid ewes with naturally-occurring ovine pregnancy toxaemia were treated with a concentrated oral dextrose and electrolyte solution administered three times daily an oral and a single subcutaneous injection of either a slow release formulation of 160mg recombinant bovine somatotropin (n = 17) or placebo injection (n = 23). A higher recovery rate was achieved in ewes treated with 160mg recombinant bovine somatotropin compared with controls (58.8 versus 34.8%, respectively), and more lambs were born alive and survived to 24th from treated ewes (15 of 46 lambs; 32.6%) compared with control ewes (12 of 62 lambs; 19.4%) but the treatment effects were not significantly different from the control group (P > 0.05).

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PubMed1998

The effects of age, weaning, drench volume and yarding on ruminoreticulum bypass in sheep, with reference to the anthelmintic efficacy of benzimidazole drenches.

AIMS: To determine the incidence of ruminoreticulum bypass in lambs before and after weaning, following drenching with anthelmintic-equivalent volumes of fluid; to investigate the influence of withholding feed for 24 hours before drenching on the incidence of ruminoreticulum bypass; and to investigate the hypothesis that ruminoreticulum bypass occurs more frequently following drenching with large than with low volumes. The relationship between these factors and the efficacy of benzimidazole anthelmintic drenches has been widely promoted in New Zealand and Australia. METHODS: Video-taped fluoroscopy, using barium sulphate suspension with a specific gravity of 1.38 as a contrast medium, was used to study closure of the reticular groove and ruminoreticulum bypass in sheep. RESULTS: When lambs were drenched with 3 ml of barium sulphate suspension/10 kg liveweight soon after removal from pasture, ruminoreticulum bypass only occurred before weaning and during the first 8 weeks after weaning. However, when a low volume drench (1 ml/10 kg) was used in lambs soon after removal from pasture during the same period, ruminoreticulum bypass was not observed. When recently weaned lambs were yarded for 24 hours before drenching with barium sulphate suspension, substantial (> or = 20%) ruminoreticulum bypass occurred in 25-58% of the animals. When 8-9 month-old hoggets were yarded for 24 hours before drenching, substantial ruminoreticulum bypass occurred in 35% of the animals. Ruminoreticulum bypass was not observed in the same group of hoggets when drenched soon after removal from pasture, in a reversed crossover experiment. This effect of withholding feed for 24 hours on ruminoreticulum bypass was significant (p < 0.0001). In hoggets which had been yarded for 24 hours before drenching with barium sulphate suspension, the incidence of ruminoreticulum bypass was significantly lower (p = 0.0026) following the use of a low volume (1 ml/10 kg) when compared to high volume (3 ml/ 10 kg) of drench. Thus, the effect of withholding feed for 24 hours on ruminoreticulum bypass was largely overcome when the low volume drench was used. CONCLUSIONS: These results support the use of low volume formulations of benzimidazole drenches for New Zealand pasture-fed lambs less than 6 months old. The results indicate that, in order to obtain the optimum efficacy of benzimidazole anthelmintics in New Zealand pasture-fed sheep, which have been yarded for 24 hours, low volume drench formulations should be used.

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PubMed1998

The effects of iodine deficiency on ewe fertility and perinatal lamb mortality.

AIMS: To substantiate a previous report of improved fertility and perinatal lamb mortality rate following iodine supplementation in a Manawatu Romney ewe flock. To contribute data which might be used to predict a response to iodine supplementation. METHODS: A controlled iodine supplementation trial was performed over 2 successive years. The possible confounding factor of different lambing paddocks on perinatal lamb mortality was removed by the reversal of the paddocks used by the supplemented and control ewes during the second year. RESULTS: During 2 successive years, iodine supplementation resulted in improved reproductive performance in a Manawatu Romney flock with 21% and 14% more lambs born to supplemented than to control mixed-age ewes in 1996 and 1997 respectively. Supplementation also resulted in improved perinatal lamb survival, although this effect was greater during the wetter 1996 Lambing season. Despite the production response during both years, a difference in lamb thyroid:bodyweight ratio was only noted following the drier 1997 winter. Ewe thyroid hormone concentrations before mating and during mid-pregnancy were poor indices of deficiency. CONCLUSIONS: Iodine deficiency should be included in the list of differential diagnoses for poor reproductive performance in ewes and in the investigation of high perinatal lamb mortality rates. CLINICAL SIGNIFICANCE: The annual cost associated with iodine deficiency in this Manawatu Romney flock is conservatively estimated at dollar 6.00 per ewe. This economic loss is considerably greater than the annual cost of iodine supplementation using iodised oil.

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PubMed1998

The efficacy of a subcutaneous injection of soluble Vitamin B12 in lambs.

AIMS: To assess the efficacy of a soluble Vitamin B12 injection in lambs by measuring changes in the serum and liver Vitamin B12 concentrations. METHODS: Thirty-six lambs were injected subcutaneously with 2 mg of soluble Vitamin B12 while another group of 36 served as untreated controls. Blood and liver biopsy samples for Vitamin B12 determinations were collected just before the injection and at days 1, 2, 5, 8, 16, 24, 30 and 45. RESULTS: The serum Vitamin B12 concentrations of the Vitamin B12 treated lambs increased rapidly compared to the untreated lambs. Concentrations peaked at day 2, decreased rapidly to day 8, and then decreased more slowly until day 24 when there were no longer differences between the groups. Liver Vitamin B12 concentrations of the Vitamin B12 treated lambs were significantly greater over days 8-24. CONCLUSION: A subcutaneous injection of 2 mg of soluble Vitamin B12 was effective in increasing and maintaining the Vitamin B12 status of lambs for about 24 days. CLINICAL SIGNIFICANCE: This Vitamin B12 product is only effective for preventing cobalt deficiency in lambs for about 4 weeks.

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PubMed1998

Recent information on iodine deficiency in New Zealand sheep flocks.

AIMS: To determine the value of pasture iodine, serum thyroxine (T4) and tri-iodothyronine (T3) concentrations and thyroid (g) to body weight (kg) ratios in lambs as criteria to predict and diagnose increased litter size and decreased perinatal mortality in response to iodine supplementation. METHODS: Results from ten iodine response trials in ewes using an oil-based intramuscular iodine preparation were reviewed along with results from investigations into goitre on five farms in the Manawatu. RESULTS: In two trials, litter size was increased by 14% and 21% in iodine-treated ewes. In only three of the 10 trials was there a significant reduction in perinatal mortality in iodine-treated ewes. CONCLUSIONS: Pasture iodine and serum thyroxine (T4) and tri-iodothyronine (T3) concentrations appeared to be unhelpful in predicting the occurrence of increased litter size and reduced perinatal mortality in response to iodine supplementation. New-born lambs from ewes not supplemented with iodine, that had a mean thyroid weight (g) to body weight (kg) ratio of 0.40 g/kg or greater, generally had a significant increase in perinatal mortality compared to lambs from iodine-supplemented ewes.

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PubMed1997

A case of "watery mouth" in a New Zealand Romney lamb.

Watery mouth was diagnosed as the cause of illness and subsequent death in a 3-day-old Romney lamb which had not received early colostrum. The history, clinical signs and post-mortem findings were typical of the disease as seen in other countries, including Great Britain. The diagnosis was based on the clinical signs and was supported by an absence of post-mortem findings of other specific neonatal diseases. The potential importance of watery mouth under conditions of intensive husbandry in New Zealand is discussed.

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PubMed1997

An investigation of the possible effects of subclinical iodine deficiency on ewe fertility and perinatal lamb mortality.

A controlled supplementation trial was performed in an assumed iodine-deficient Romney ewe flock in the Manawatu. Significantly more twin litters were born to iodine-supplemented ewes than to control ewes. Furthermore, the perinatal mortality rate in lambs born to iodine-supplemented dams was significantly lower than in lambs born to control dams. Ewe age and the use of different lambing paddocks for iodine-supplemented and control ewes may have been confounding factors. In both iodine-supplemented and control ewes, serum T3, and T4, concentration values remained above the currently used normal range throughout the trial period.

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PubMed1996

Concurrent bovine viral diarrhoea virus and Salmonella typhimurium DT104 infection in a group of pregnant dairy heifers.

Two days after being imported into the United Kingdom one of a group of 30 pregnant dairy heifers showed clinical signs of bovine viral diarrhoea virus (BVDV) infection and subsequently died. Before it died the heifer was BVDV antigen-positive and antibody-negative. The gross post mortem findings were suggestive of mucosal disease but in addition to noncytopathic BVD virus, Salmonella typhimurium DT104 was cultured from tissues and gut contents. The other heifers were screened for S typhimurium by culturing faeces, and serology showed that 13 (45 per cent) of the group seroconverted to BVDV in the three weeks between samplings and the remainder were seropositive, indicating previous exposure. During this period four heifers showed clinical signs of acute BVDV infection but recovered uneventfully. Four animals (14 per cent) were positive for S typhimurium DT104 on faecal culture, and three of these excretors concurrently seroconverted to BVDV. Of the 29 heifers remaining in the group, one aborted in late gestation, 26 bore live calves and two delivered stillborn calves. Pre-colostral blood samples from the calves showed that their dams' pre-existing antibody titres correlated well with in utero fetal protection. In non-immune dams, exposure to BVDV between 69 and 120 days of gestation led to the birth of live persistently viraemic calves. Infection between 120 and 140 days of gestation led to the birth of live calves with evidence of congenital damage to the central nervous system, and infection later than 140 days of gestation led to the birth of live, normal calves with high pre-colostral antibody titres to BVDV. One calf which sucked colostrum was antibody and virus antigen-positive when sampled at 12 hours old but regular blood sampling failed to detect viraemia again until the calf was seven weeks old when it became persistently viraemic.

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PubMed1996

Observations on the efficacy of mass treatment by subconjunctival penicillin injection for the control of an outbreak of infectious bovine keratoconjunctivitis.

Infectious bovine keratoconjunctivitis was diagnosed on a Manawatu beef cattle farm, with inflammation of 85% of eyes in a group of 150 6-month-old-calves. Comeal inflammation was recorded in 23% of eyes. All active lesions healed over a 3-week period following whole group subconjunctival penicillin injection. Morarellu bovis was cultured from two of seven conjunctival swabs at the time oftreatment and from four of six conjunctival swabs 9 days after treatment. Concurrently, pink-eye was noted in older cattle, with inflammation in 50% of eyes. For practical handling reasons, these older cattle were not treated. Despite nontreatment, their clinical signs regressed over a 3-week period. The rationale of whole group treatment for the control of infectious bovine keratoconjunctivitis is discussed.

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PubMed1996

Use of tilmicosin in a severe outbreak of respiratory disease in weaned beef calves.

Severe respiratory disease, associated with seroconversion to bovine respiratory syncitial virus (BRSV), caused the death of two cattle and necessitated antibiotic treatment of 70 calves (rectal temperature of 39.6 degrees C or greater) from a group of 96 (73%) during an 8-day period. Tilmicosin injection resulted in a reduction in median rectal temperature from 40.3 degrees C to 39.2 degrees C and 39.0 degrees C for the first and second days after treatment. The rectal temperature was 39.5 degrees C or lower in 72% (48 of 67) and 96% (64 of 67) of cattle 1 and 2 days after tilmicosin treatment, respectively. Ten cattle were re-treated with tilmicosin 6 to 16 days after the first treatment. Our study demonstrated that bovine respiratory syncytial virus infection could cause severe respiratory disease in a beef herd that had no previous history of BRSV-related disease. Secondary bacterial invasion after BRSV infection was controlled effectively by tilmicosin treatment but repeat antibiotic treatments were occasionally necessary due to bacterial re-infection of the respiratory tract.

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