Farm-level risk factors and treatment protocols for lameness in New Zealand dairy cattle.

AIMS: To identify farm-level risk factors for dairy cow lameness, and to describe lameness treatment protocols used on New Zealand dairy farms. METHODS: One hundred and nineteen farms from eight veterinary clinics within the major dairying regions of New Zealand were randomly enrolled into a cross-sectional lameness prevalence study. Each farmer completed a questionnaire on lameness risk factors and lameness treatment and management. Trained observers lameness scored cattle on two occasions, between October-December (spring, coinciding with peak lactation for most farms) and between January-March (summer, late lactation for most farms). A four-point (0-3) scoring system was used to assess lameness, with animals with a lameness score (LS) ≥2 defined as lame. At each visit, all lactating animals were scored including animals that had previously been identified lame by the farmer. Associations between the farmer-reported risk factors and lameness were determined using mixed logistic regression models in a Bayesian framework, with farm and score event as random effects. RESULTS: A lameness prevalence of 3.5% (2,113/59,631) was reported at the first LS event, and 3.3% (1,861/55,929) at the second LS event. There was a median prevalence of 2.8% (min 0, max 17.0%) from the 119 farms. Most farmers (90/117; 77%) relied on informal identification by farm staff to identify lame animals. On 65% (75/116) of farms, there was no external provider of lame cow treatments, with the farmer carrying out all lame cow treatments. Most farmers had no formal training (69/112; 62%). Animals from farms that used concrete stand-off pads during periods of inclement weather had 1.45 times the odds of lameness compared to animals on farms that did not use concrete stand-off pads (95% equal-tailed credible interval 1.07-1.88). Animals from farms that reported peak lameness incidence from January to June or all year-round, had 0.64 times odds of lameness compared to animals from farms that reported peak lameness incidence from July to December (95% equal-tailed credible interval 0.47-0.88). CONCLUSIONS: Lameness prevalence was low amongst the enrolled farms. Use of concrete stand-off pads and timing of peak lameness incidence were associated with odds of lameness. CLINICAL RELEVANCE: Veterinarians should be encouraging farmers to have formal lameness identification protocols and lameness management plans in place. There is ample opportunity to provide training to farmers for lame cow treatment. Management of cows on stand-off pads should consider the likely impact on lameness.

Can lameness prevalence in dairy herds be predicted from farmers' reports of their motivation to control lameness and barriers to doing so? An observational study from New Zealand.

Understanding what motivates and prevents behavioral change in farmers is a critical step in disease control in dairy cattle. A total of 101 New Zealand dairy farmers across 8 regions were randomly enrolled into a cross-sectional study to investigate farmer barriers and motivators to lameness control for cows managed 100% at pasture and the relationship between these responses and the true lameness status on farm. Trained technicians lameness scored all lactating cows on the enrolled farms on 2 occasions during one lactation. Farm-level prevalence proportions were calculated as the mean of the 2 lameness scores. Enrolled farmers were asked their perception of lameness in the current milking season and responded to 26 ordinal Likert-type items with 5 options ranging from not important at all to extremely important. The questions were grouped under 3 categories; barriers to lameness control (n = 9), impacts of lameness (n = 10), and motivators to control lameness (n = 7). The association between farmer perception of lameness and lameness prevalence was reported using linear regression. Multiple-factor analysis was conducted to identify latent variable themes within the responses. Linear discriminant analysis was used to assess whether barriers, impacts, and motivators could be used to predict farmer perception of lameness and lameness prevalence. Lameness prevalence was 0.8% greater on farms where farmers perceived lameness as a moderate or a major problem compared with farms where the farmer perceived lameness as a minor problem or not a problem. Farmers ranked all potential motivators to lameness control as important and declared few barriers to be important at preventing them from controlling lameness. Feeling sorry for lame cows and pride in a healthy herd were the most important motivators, with lack of time and skilled labor the most important barriers. The most important effects of lameness were cow-related factors such as pain and production, with farm and industry impacts of less importance. Farmers place different weightings of importance on barriers to lameness control compared with motivators for lameness control. The impacts and motivators were strongly correlated with the first dimension from the multiple-factor analysis, with only weak correlation between barriers and the first dimension. Linear discriminant analysis identified that the importance that farmers place on barriers, motivators, and impacts of lameness were poor predictors of farmers' belief in regard to their lameness problem or actual lameness prevalence (above or below the median lameness prevalence for the study cohort). Despite relatively low lameness prevalence, many New Zealand dairy farmers believe lameness is a problem on their farm, and they rank welfare effects of lameness of high importance. To investigate how farmer behavior change can be used to manage lameness, future studies should consider theoretical social science frameworks beyond the theory of planned behavior or involve prospective interventional studies investigating farmer actions instead of beliefs.

Investigating the effect of prophylactic claw trimming on the interval between calving and first observed elevated locomotion score in pasture-based dairy cows.

AIMS: To evaluate, in a pasture-based dairy herd, the response to a three-time point hoof trimming regime on lameness incidence and time from calving to observation of an elevated locomotion score (LS). METHODS: This study was conducted on a 940-cow spring-calving herd in New Zealand's North Island between May 2018 and May 2019. Cows (n = 250) were randomly allocated to the hoof trimming group, with the remainder assigned to the non-trim cohort. One trained professional hoof trimmer used the five-step Dutch method to trim the hind feet of the trimming group. Throughout the subsequent production season, the whole herd was locomotion-scored fortnightly using the 4-point (0-3) Dairy NZ lameness score. Kaplan-Meier survival curves were used to assess the univariable effect of trimming on the interval between calving and first LS of ≥ 2 and first LS ≥ 1. A multivariable Cox proportional hazards regression was used to further evaluate the effect of trimming on time to elevated LS. RESULTS: Mean lameness (LS ≥ 2) prevalence was 2.6%, with 30% of cows having ≥ 4 observations during the study period when at least one LS was ≥ 2. For LS ≥ 1, mean prevalence was 40%, with 98.6% of cows having ≥ 4 observations during the study period when at least one LS was ≥ 1 during lactation. Hoof trimming had no apparent effect on the incidence of clinical lameness (LS ≥ 2) (trimmed vs. non-trimmed: 33.2% vs. 28.8%, respectively), but for LS ≥ 1, there was a small decrease in the incidence of LS ≥ 1 (trimmed vs. non-trimmed: 96.9% vs. 99.3%, respectively). The hazard of a cow having a first observed LS ≥ 2 in the control group was 0.87 (95% CI = 0.66-1.14) times that of the trimmed group; however, the hazard of a cow having a first LS ≥ 1 was 1.60 (95% CI = 1.37-1.88) times higher in the control than in the trimmed group. CONCLUSION AND CLINICAL RELEVANCE: On this farm, prophylactic hoof trimming had no clinically relevant impact on the incidence of clinical lameness and was not associated with clinically beneficial reductions in time to first observed LS ≥ 2. This may be because claw horn imbalance was not pronounced on this farm, with 53% of cows needing no trim on either hind limb on the first trimming occasion. Further research on the response to prophylactic trimming in pasture-based dairy cattle is required.

Lameness recovery rates following treatment of dairy cattle with claw horn lameness in the Waikato region of New Zealand.

AIMS: To describe the time in days for lame dairy cows to recover after diagnosis and treatment of claw horn lameness, and to investigate whether cure rates differed between farms. METHODS: Five dairy farms in the Waikato region were conveniently enrolled into a descriptive epidemiological study. Three of these farms had dairy cattle enrolled over two consecutive seasons, while two farms enrolled for one year. Lame cattle diagnosed by the farmers were enrolled into the study if they had a lameness score (LS ≥ 2 on a 0-3 scale) and claw horn lesions. All enrolled animals were treated by a single veterinarian following a consistent methodology, and subsequently assessed for LS at a median frequency of 4 days from enrolment until they were sound (LS = 0). The times (days) taken for animals to become sound and non-lame (LS < 2) were reported for all animals, and Kaplan-Meier survival curves used to present the results. A Cox-proportional hazard model was used to assess if the hazard of soundness was associated with farm, age, breed, lesion, number of limbs involved, and LS at enrolment. RESULTS: A total of 241 lame cattle with claw horn lesions were enrolled across the five farms. White line disease was the predominant pain-causing lesion in 225 (93%) animals, and blocks were applied to 205 (85%) of enrolled animals. The overall median days from enrolment to becoming sound was 18 (95% CI = 14-21) days, and 7 (95% CI = 7-8) days to become non-lame. A difference in the hazards of lameness cure between farms was identified (p = 0.007), with median days to lameness cure between farms ranging from 11 to 21 days. No associations were identified between age, breed, limb, or LS at enrolment on the lameness cure rates. CONCLUSIONS: Treatment of claw horn lameness following industry-standard guidelines in dairy cattle on five New Zealand dairy farms resulted in rapid cure, although cure rates differed between farms. CLINICAL RELEVANCE: Following industry best-practice lameness treatment guidelines, including frequent use of blocks, can result in rapid lameness cure rates in New Zealand dairy cows. This study also suggests that management of lame cattle on pasture can positively benefit their welfare and recovery times. The reported cure rates provide veterinarians with benchmarks on the length of time after which a lame animal should be re-examined, and in the investigation of poor treatment response rates at the herd level.

Persistence of orthopaedic hoof blocks for the treatment of lame cattle kept permanently at pasture.

AIMS: To compare the retention by New Zealand dairy cows kept at pasture in a lame cow group, of three hoof block products commonly used in the remediation of lameness. METHODS: Sixty-seven farmer-presented Friesian and Friesian x Jersey dairy cows from a single herd in the Manawatu region (New Zealand) suffering from unilateral hind limb lameness attributable to a claw horn lesion (CHL) were randomly allocated to one of three treatments: foam block (FB), plastic shoe (PS) and a standard wooden block (WB). Blocks were applied to the contralateral healthy claw and checked daily by the farm staff (present/not present) and date of loss was recorded. Blocks were reassessed on Day 14 and Day 28 and then removed unless further elevation was indicated. Daily walking distances were calculated using a farm map and measurement software. Statistical analyses included a linear marginal model for distance walked until block loss and a Cox regression model for the relative hazard of a block being lost. RESULTS: Random allocation meant that differences between products in proportion used on left or right hind foot or lateral or medial claw were small. Mean distance walked/cow/day on farm tracks whilst the block was present was 0.32 (min 0.12, max 0.45) km/day; no biologically important difference between products in the mean distance walked was identified. Compared to PS, cows in the WB group were five times more likely to lose the block (HR = 4.8 (95% CI = 1.8-12.4)), while cows in the FB group were 9.5 times more likely to lose the block (HR = 9.5 (95% CI = 3.6-24.4)). CONCLUSIONS: In this study, PS were retained for much longer than either FB or WB. As cows were managed in a lame cow group for the study duration, walking distances were low and did not impact on the risk of block loss. More data are needed to define ideal block retention time. CLINICAL RELEVANCE: In cows with CHL the choice of block could be based on the type of lesion present and the expected re-epithelisation times.

A pilot monitoring strategy for post-partum disease in an Australian dairy herd.

AIMS: To design a monitoring strategy that could be applied to regular veterinary visits to dairy farms to assess the prevalence and association between health conditions (uterine disease, hyperketonaemia and suboptimal body condition score) when diagnosed and treated at 1-7 days post-calving (DPC) and then re-examined at 28-35 DPC. METHODS: This study evaluated data from 187 high-yielding dairy cows (21 primiparous, 166 multiparous) on one South Australian dairy farm on two occasions; Visit A which was 1-7 DPC and Visit B which was 28-35 DPC. On each visit, the nature of vaginal discharge, concentration of beta-hydroxybutyrate (BOH) in blood and BCS were recorded and assigned a clinical score. This was converted to a categorical outcome denoting the presence or absence of an abnormal health event, namely metritis or endometritis, hyperketonaemia (BOH concentration ≥1.2 mm/L) and suboptimal body condition score (>0.5 from optimum score). Cows with uterine disease or hyperketonaemia at either visit were treated. The prevalence of abnormal health events at each visit was determined and the association between the prevalence of disease at Visit A and Visit B (following appropriate treatment at Visit A) was measured using regression analysis. RESULTS: The prevalence of abnormal vaginal discharge, hyperketonaemia and suboptimal BCS at Visits A and B were 26%, 7%, 35% and 25%,16%, 33% respectively. A higher proportion of primiparous cows (Visit A: 0.86 (95% CI = 0.70-1.00); Visit B: 0.95 (95% CI = 0.86-1.00)) were found to have suboptimal BCS at both visits compared to multiparous cows (Visit A: 0.28 (95% CI = 0.20-0.35); Visit B: 0.24 (95% CI = 0.17-0.32)). A higher prevalence of hyperketonaemia at Visit B for multiparous compared to primiparous cows (19 (95% CI = 12-25)% vs. 0 (95% CI = 0-17) respectively) was identified. An increase in clinical discharge score at Visit A increased the odds of purulent vaginal discharge at Visit B (OR = 1.77 (95% CI = 1.31-2.40)). Failing to calve at target BCS was strongly associated with cows missing target BCS at Visit B (OR = 5.77 (95% CI = 2.35-13.11)) and for every unit increase in BCS at Visit A, BCS at Visit B increased by 0.40 (95% CI = 0.26-0.53). CONCLUSIONS AND CLINICAL RELEVANCE: This study describes a pilot monitoring strategy for clinical parameters indicative of post-partum disease at 1-7 and 28-35 DPC. Determining the herd prevalence of these conditions will enable tracking of herd disease status over time.Abbreviations: BCS: Body condition score; BOH: Beta-hydroxybutyrate; DPC: Days post-calving; NEFA: Non-esterified fatty acids; SCHK: Subclinical hyperketonaemia.

An evaluation of the changes in distance from the external sole surface to the distal phalanx in heifers in their first lactation.

Thin soles are a significant cause of lameness in dairy cattle but in most cases the diagnosis is based on subjective assessment. Ultrasonography has been used to more directly estimate sole thickness, but mostly on a one-off basis or over a short period of time. Data over a longer period of time (such as a lactation period) are lacking and there are no descriptions of the normal changes that occur over time and to show how sole thickness at calving relates to thickness later in lactation. This study measured the distance between the external sole surface and the distal phalanx (DP) in 25 mixed breed (Jersey cross Friesian and Friesian) heifers on five occasions over their first lactation (approximately 10, 60, 110, 160 and 220 days post calving). There was a significant effect of claw (medial/lateral) and of time after calving on DP. Mean DP was highest on day 10 and was lowest on day 110 at the tip of the distal phalanx (S1) and on day 160 25 mm towards the heel from the tip (S2). DP was greater at S1 in medial claws and S2 in lateral claws. Although mean DP decreased between days 10 and 110, this change was correlated to DP at day 10. At S1 claws with a DP of <7.5mm tended to increase in thickness between day 10 and 110. Claws which were ≤ 8.25 mm at day 10 were 2.43 (95% CI 0.86-6.89) times more likely to be thin (<7.0mm) at day 110, but of the 12 thin claws at day 110, six had had an adequate DP (>8.25 mm) at day 10. A single measurement of DP at calving was not an effective method for predicting which claws would became thin during lactation.

Validation of a portable ultrasound machine for estimating sole thickness in dairy cattle in New Zealand.

AIM: The aim of the study was to validate the use of a portable ultrasound machine for monitoring sole thickness by investigating the agreement between ultrasound and electronic calliper measurement of distance from the external to the internal sole surface (sole thickness) and the distance from the external sole surface to the distal phalanx (DP). METHODS: Distal limbs were collected post-mortem from 24 dairy cows. Measurements were made using a portable ultrasound machine (Mindray DP 6600) on both claws of the right hind and left front feet at the tip of the distal phalanx (site 1) and 25 mm towards the heel (site 2). DP and sole thickness were measured at each site. The limbs were then frozen and sectioned, and the same parameters measured using electronic callipers. The limits-of-agreement between the two methods were investigated, and receiver operator characteristic (ROC) analyses undertaken. RESULTS: Ultrasound images were obtained for 92 out of 96 claws. For sole thickness, as measured using callipers, the best correlation was with ultrasound-measured DP at site 1 (r=0.77). The mean difference between these two measures was 2.5 (SEM 0.15) mm and the range of the 95% limits-of-agreement was 4.2 mm. ROC analysis showed that a claw with an ultrasound-measured DP of <7.0 mm was >11 times more likely to have a sole thickness <5 mm than ≥ 5 mm, while a claw with an ultrasound-measured DP of >8.25 mm was 4.5 times more likely to have a sole thickness ≥ 5 mm than <5 mm. Soles could therefore be categorised as thin (DP < 7 mm), marginal (DP 7-8.25 mm) or adequate (DP >8.25 mm) using this ultrasound machine. CONCLUSIONS: Examination of the claws of dairy cows using a basic portable ultrasound machine is sufficiently accurate for use in monitoring mean sole thickness in a group of animals. On an individual basis, measurement of DP can be used to categorise soles as thin, marginal or adequate. CLINICAL RELEVANCE: The measurement of DP using portable ultrasonography can be used to evaluate the role of sole thickness in clinical lameness outbreaks, and as a research tool to monitor the dynamics of claw parameters over time.

An outbreak of toe ulcers, sole ulcers and white line disease in a group of dairy heifers immediately after calving.

CASE HISTORY: An outbreak of severe lameness was reported on a 780-cow spring-calving dairy herd in the Manawatu region within 1-3 weeks of calving, which affected over 90% of a group of 150 dairy heifers. Approximately 3 weeks before the planned start of calving heifers had been fed maize and grass silage on a concrete feed pad for 3-4 h per day, and mixed with a group of adult cows. CLINICAL FINDINGS: During treatment for lameness, the feet of 28 lame heifers were closely examined. Seventy lesions were recorded in the claws of these heifers. The predominant lesion was severe solar and white line haemorrhage, with much of the haemorrhage focussed at the site at which sole ulcers are normally seen. White line disease was seen in nine claws and sole ulcers in four. Additionally, a lesion which is not commonly recorded in New Zealand, a toe abscess arising from separation of the white line from the sole in the abaxial region of tip of the toe was recorded in 11 claws. The clinical impression was that the soles of the affected heifers were very thin. This was supported by examination of the feet of eight heifers using ultrasonography that indicated heifers with hoof horn haemorrhages had very thin soles (estimated mean 4.1 mm) and that these soles were thinner than those in non-lame heifers without haemorrhages. DIAGNOSIS: The pattern of disease seen in these heifers closely matched that seen in an outbreak of lameness in heifers in Florida, which was linked to thin soles resulting from excess hoof horn wear. The clinical signs and findings of the examination using ultrasonography strongly implicated thin soles as the underlying cause of lameness on this farm. An on-farm investigation revealed a combination of heifer behaviour and prolonged exposure to wet concrete on the feed pad were the primary causes of excess wear that resulted in thin soles. CLINICAL RELEVANCE: This was an unusual outbreak of lameness in a group of newly calved heifers. The problem highlights the value of good management during the transition of heifers at pasture to the lactating herd standing on concrete for long periods, in the control of lameness.

Causes of urinary incontinence after acute hemispheric stroke.

BACKGROUND AND PURPOSE: We prospectively studied bladder function in stroke patients to determine the mechanisms responsible for poststroke urinary incontinence. METHODS: Fifty-one patients with recent unilateral ischemic hemispheric stroke admitted to a neurorehabilitation unit were enrolled. The presence of urinary incontinence was correlated with infarct location, neurological deficits, and functional status. Urodynamic studies were performed on all incontinent patients. RESULTS: Nineteen patients (37%) were incontinent. Incontinence was associated with large infarcts, aphasia, cognitive impairment, and functional disability (p < 0.05) but not with age, sex, side of stroke, or time from stroke to entry in the study. Urodynamic studies, performed on all 19 incontinent patients, revealed bladder hyperreflexia in 37%, normal studies in 37%, bladder hyporeflexia in 21%, and detrusor-sphincter dyssynergia in 5%. All of the patients with normal urodynamic studies were aphasic, demented, or severely functionally impaired. All of the patients with hyporeflexic bladders had underlying diabetes or were taking anticholinergic medications. Forty-six percent of incontinent patients treated with scheduled voiding alone were continent at discharge compared with 17% of patients treated pharmacologically. CONCLUSIONS: There are three major mechanisms responsible for poststroke urinary incontinence: 1) disruption of the neuromicturition pathways, resulting in bladder hyperreflexia and urgency incontinence; 2) incontinence due to stroke-related cognitive and language deficits, with normal bladder function; and 3) concurrent neuropathy or medication use, resulting in bladder hyporeflexia and overflow incontinence. Urodynamic studies are of benefit in establishing the cause of incontinence. Scheduled voiding is a useful first-line treatment in many cases of incontinence.