An automated in-line clinical mastitis detection system using measurement of conductivity from foremilk of individual udder quarters

AIM: To assess a novel method for automatic in-line detection of clinical mastitis.

METHODS: For a brief period at the start of milking for each cow, electrical conductivity of foremilk was measured for each quarter in turn, using a single sensor installed in the long milk tube (LMT) about 1.5 m downstream from the milking-machine claw. Sequential separation of flow between udder quarters was achieved by control of pulsation to individual teatcups within a conventional cluster. The ratio of conductivity values between quarters was used as an indicator of mastitis status. The concept was evaluated initially in a pilot trial in a 200-cow herd milked in a 23-stall swing-over herringbone milking parlour. It was then tested rigorously in a field trial in a 640-cow herd milked in a 50-stall rotary milking parlour. Both trials were conducted in the Waikato region of New Zealand. In the latter trial, sensor results were compared with visual inspection of a commercial in-line mastitis filter fitted to each milking unit. These filters were inspected for clots immediately after every cow's milking, for 3 weeks. The dataset of approximately 27,000 individual milkings was tested against several published or potential alter- native ‘gold standards’ for diagnosing clinical mastitis.

RESULTS: In the pilot trial, 12–14 clinical events were detected out of 19 true clinical quarters, with a false-alert rate of between three and five false electrical-conductivity alerts per 1,000 individual milkings. In the more rigorous field trial, sensitivity ranged from 68 to 88%, and the false-alert rate (false-alert episodes per 1,000 individual milkings) ranged from 2.3 to 7.0.

CONCLUSION: The novel clinical mastitis detection system, based on separation of the flow and measurement of electrical conductivity from foremilk of individual udder quarters, has the potential to provide a new tool for helping farmers to monitor clinical mastitis in herds milked with conventional clusters.     

Effect of dry period length on the effect of an intramammary teat sealant on the risk of mastitis in cattle treated with antibiotics at drying off

AIM: The aim of this study was to evaluate, under farm conditions, the use of a teat sealant in addition to whole herd dry cow antibiotic therapy on the risk of clinical mastitis in dairy cattle at pasture, and to evaluate the impact of dry period length on that risk and the impact of the teat sealant on that risk.

METHODS: Dairy cows in three herds which used routine whole herd antibiotic therapy were randomly assigned to receive either treatment with an internal teat sealant (n=322) or no additional treatment (n=313) at drying-off between March and May 2010. All clinical mastitis cases during the dry period and to the end of the subsequent lactation were recorded by farm staff; factors affecting risk of clinical mastitis were then analysed using a Cox proportional hazards model.

RESULTS: Median duration of the dry period was 112 days with >25% of cows having a dry period >130 days. The incidence risk of mastitis during lactation for cows treated with teat sealant was 9.9 (95% CI=6.9–13.7) cases per 100 cows compared with 17.9 (95% CI=13.8–22.6) cases per 100 cows for cows treated with antibiotic alone. The addition of a teat sealant to dry cow antibiotic therapy decreased the risk of clinical mastitis only in the first 33 days after calving (Hazard risk 0.24 (95% CI=0.12–0.48)). Length of dry period did not significantly affect the risk of clinical mastitis, or the effect of adding teat sealant to dry cow antibiotic therapy on the risk of clinical mastitis.

CONCLUSIONS: In these herds where, based on the mastitis history, whole herd antibiotic therapy had been recommended, the use of a teat sealant significantly reduced the risk of clinical mastitis. This effect was limited to the first 33 days after calving; subsequently there was no significant effect of treatment. There was no effect of dry period length on risk of clinical mastitis, nor any significant interaction with treatment.

CLINICAL RELEVANCE: Combination therapy with teat sealant and antibiotic was effective under New Zealand conditions in herds using whole herd antibiotic treatment at drying off. Teat sealant reduced risk of clinical mastitis in cattle with dry periods substantially longer than 100 days, and there was no evidence that this effect changed as dry period length increased.     

Effects of a topically applied anaesthetic on the behaviour,pain sensitivity and weight gain of dairy calves following thermocautery disbudding with a local anaesthetic

ABSTRACT

Aims: To compare the effect of a topically applied anaesthetic to no pain relief or meloxicam on the behavioural responses, pain sensitivity and weight gain of calves following disbudding with or without sedation.

Methods: A total of 364, 2–6 week-old calves from three commercial farms were systematically allocated to one of six treatment groups. All calves received a cornual nerve block prior to disbudding, with half restrained in a crate and half sedated with xylazine. Within these groups one third received no further treatment (control), one third were treated with meloxicam >10?minutes prior to disbudding and one third received a topical anaesthetic applied to the horn bud wounds following disbudding. The frequency of ear flicks, head shakes, head scratches and pain sensitivity of the wound were recorded on up to eight occasions over 24 hours after disbudding. Calves were weighed before, and 7 and 28 days after, disbudding to determine average daily weight gain (ADG).

Results: Compared to calves in the crate-control group, all other groups had reduced ear flicks at all times following disbudding (p?<?0.01). Treatment with meloxicam and topical anaesthesia in addition to sedation reduced head scratches compared to calves in the crate-control group (p?≤?0.013). At 22 hours after disbudding head shakes were reduced in sedated calves treated with topical anaesthetic compared to calves in the crate-control group (p?<?0.001). Pain sensitivity was lower in all sedated calves than unsedated calves (p?<?0.001). The ADG between Days 0–7 was 0.14 (95% CI?=?0.015–0.274) kg/day greater in sedated calves treated with meloxicam than calves in the crate-control group (p?=?0.03), and the ADG between Days 0–28 tended to be 0.06 (95% CI=?0.01–0.13) kg/day greater in sedated calves treated with topical anaesthetic than calves in the crate-control group (p?=?0.09).

Conclusion and clinical relevance: Sedation of calves for disbudding reduced the pain experienced in the following 24 hours. There was a benefit to providing calves with topical anaesthetic following disbudding on behavioural responses and pain sensitivity, which was similar to that of treating calves with meloxicam.     

A lymphoproliferative disease in Manx cats with similarities to autoimmune lymphoproliferative syndrome (ALPS) in people

In 2009–2010, an unusual lymphoproliferative disease was identified in multiple siblings from successive litters of Manx cats, suggesting a genetic predisposition to development of this disease. Presentation of disease in the cats had multiple similarities with the human disease ALPS, a rare inherited disorder that causes persistent lymphoproliferation, together with variable manifestations of autoimmunity and increased susceptibility to neoplasia. The majority of human ALPS patients have inherited Fas gene mutations, causing defective apoptosis of lymphocytes, although for a proportion of ALPS patients the underlying genetic mutations remain unknown. In order to identify the likely mode of inheritance of the disease, further matings of potential carrier cats are in progress. Studies to investigate the potential role of abnormalities in the Fas gene in the development of the disease in cats are also proposed. Identifying and further characterising the nature and mechanism of the disease in cats may allow better understanding of the development, progression, and treatment of ALPS in humans.     

Nephrogenic diabetes insipidus in a 14-year-old gelding

Abstract

CASE HISTORY: A 14-year-old Cleveland Bay cross gelding was presented with severe urinary incontinence that had been present for 1 year, and chronic polydipsia and polyuria over 4 years. Water intake had been recorded as 240 L over a 24-hour period.

CLINICAL FINDINGS: The horse had marked urinary incontinence and polyuria and polydipsia. The urine was markedly hyposthenuric, but no abnormalities on urinalysis were detected. There were no other abnormal clinical or neurological signs. Haematological and serum biochemical examinations showed no abnormalities and ultrasonographic and endoscopic examination of the urinary tract did not reveal any abnormalities. The horse underwent a modified water deprivation test and failed to concentrate its urine after 5 days. 1-desamino-8-d-arginine vasopressin (DDAVP) was administered I/V but the urine remained isosthenuric with a specific gravity of 1.010.

DIAGNOSIS: Nephrogenic diabetes insipidus. A definitive cause of the urinary incontinence was not found but overflow incontinence was considered a possibility.

CLINICAL RELEVENCE: Despite being a rare condition in the horse diabetes insipidus should be considered in cases of severe polydipsia and polyuria in mature horses.     

Suspected inherited rickets in Corriedale sheep

A suspected inherited form of rickets was diagnosed in Corriedale sheep on a commercial sheep farm in Marlborough. Affected lambs were normal at birth but showed a reduced growth rate and a range of skeletal abnormalities, including both varus and valgus deformities and a characteristic dip in the shoulder region. Up to 20 affected lambs had been born on the property over the last two seasons. Skeletal lesions in affected lambs included swollen costochondral junctions, moderate to marked thickening of physes in long bones, and collapse of weakened subchondral bone, particularly in the proximal humerus. These lesions, together with the microscopic changes, strongly suggested a diagnosis of rickets. Affected lambs were hypocalcaemic and hypophosphataemic, consistent with a deficiency of vitamin D.

Vitamin D assays revealed significantly higher 1,25(OH) vitamin D concentrations in affected lambs than in controls, suggesting a defect in the vitamin D receptor as the likely mechanism. DNA testing revealed that 4/10 Corriedale rams used during the previous season had sired affected lambs. Studies aimed at confirming the genetic nature of the disease and the mechanism are continuing at Massey University.     

Copper deficiency in sheep: An assessment of the relationship between concentrations of copper in serum and plasma

AIM: To assess the relationship between concentrations of copper in serum and plasma in sheep.

METHODS: Concentrations of Cu were measured in paired serum and heparinised plasma samples collected from 110 sheep in nine flocks. Linear regression was used to evaluate whether flock or gender had a significant effect on the association between concentrations of Cu in serum and plasma. The individual results for concentrations of Cu in serum were then compared with those from plasma, using correlation and limits of agreement plotting.

RESULTS: Concentrations of Cu in serum ranged from 7.3 to 22 (mean 14.0) µmol/L, while concentrations in plasma ranged from 9 to 27 (mean 16.3) µmol/L. On average, concentrations of Cu in serum were 2.3 µmol/L lower than in plasma. Over the range of values seen in this study, concentrations of Cu in plasma and serum were significantly correlated (r=0.89), and mean concentrations in serum were 87% of those in plasma. There was no effect of flock or gender on the relationship between concentrations of Cu in serum and plasma. Despite the significant correlation, there was marked variability between individual samples in the proportion of Cu that was lost during clotting, with the 95% limits of agreement for serum Cu ranging from 70 to 104% of the plasma concentration.

CONCLUSIONS: As in cattle, the individual variability in the loss of Cu during clotting in sheep is too great for concentration of Cu in serum to be used as a substitute for that in plasma.

CLINICAL RELEVANCE: When assessing the blood Cu pool as part of the diagnosis of Cu-responsive disease in sheep, the concentration of Cu in plasma should be measured in preference to that of serum. We suggest that a range of 4.5 to 9 µmol/L in plasma be used to define marginal Cu status in sheep.