Some observations on the incidence of lameness in dairy cattle in Somerset

Pathogenesis and Treatment of Bovine Foot Rot

Bovine foot rot (BFR) is an infectious disease of the interdigital skin and subcutaneous tissues of beef and dairy cattle that occurs under a variety of management and environmental settings. The anaerobic, gram-negative bacteria Fusobacterium necrophorum, Porphyromonas levii, and Prevotella intermedia are commonly isolated from lesions. A multitude of host, agent, and environmental factors contribute to the development of BFR. Initiation of systemic antimicrobial therapy early in the course of disease commonly leads to resolution. Delays in treatment may result in extension of infection into deeper bone, synovial structures, or ligamentous structures, and the prognosis for recovery is reduced.

Further investigation of lameness in cows at pasture: an analysis of the lesions found in, and some possible risk factors associated with, lame New Zealand dairy cattle requiring veterinary treatment

Previous descriptive analysis of data collected from veterinary visits to lame cows in the Taranaki region of New Zealand between December 1995 and July 2007 showed an association between both breed and age and lesion type and site. However, that simple analysis had significant limitations as it did not take account of more than 2 factors at the same time and did not evaluate the effect of time (either year or season). This analysis was designed to overcome those limitations. First, correspondence analysis, a multivariate method of analysis, was used to simultaneously evaluate the relationship between the 3 most commonly recorded causes of lameness (i.e., white line disease, sole injury, and axial disease, all of which are diseases of the claw horn), and 4 groups of predictor variables: foot (front or hind), breed (Jersey or Friesian), age (heifer or cow), and claw (lateral or medial). Second, time series analysis was used to ascertain the effect of season on lesion type and identify the change over years in proportional morbidity. The correspondence analysis clearly separated the 3 diseases, showing that differences between these 3 diseases in their risk factors and their etiology. Each disease clustered with a group of predictor variables. White line disease was linked to lateral claw, hind foot, cow, and Friesian breed; sole injury was linked to heifer and medial claw; and axial disease to Jersey and front foot. As sole injury and axial disease are diseases that occur principally in cows at pasture, this is the first full analysis of risk factors for those diseases. The time series analysis further strengthened the conclusion that these 3 diseases have different risk factors, as, even in the strongly seasonal New Zealand system, significant differences in seasonality occurred between them. This analysis adds further to the data which show that claw horn diseases have different etiologies and need to be treated separately for both research purposes and for lameness management on-farm. This analysis is only a starting point; more research is required, particularly longitudinal studies, to better understand the differences in etiology between the main causes of lameness due to claw horn disease, especially in cows kept at pasture, so that we can better target prevention.

Effects of retinoic acid and hydrogen peroxide on sterol regulatory element-binding protein-1a activation during adipogenic differentiation of 3T3-L1 cells

Both retinoic acid (RA) and oxidative stress (H2O2) increased transcription and cleavage of membrane-bound sterol regulatory element-binding protein (SREBP)-1, leading to enhanced transcription of fatty acid synthase (FAS) in hepatoma cells. On the other hand, RA and H2O2 decreased and increased lipogenesis in adipocytes, respectively, although roles of SREBP-1 activation in these effects remain to be elucidated. To elucidate its involvement, we examined the activation of SREBP-la, expression of FAS genes and lipid accumulation in 3T3-L1 cells in the presence of RA and/or H2O2. RA (1 microM) treatment suppressed expression of SREBP-1a and FAS genes and lipid accumulation. H2O2 (2 microM) treatment induced increased cleavage of SREBP-1a, without affecting amounts of SREBP-1a mRNA and precursor protein, and enhanced expression of FAS gene and lipid accumulation. Increased cleavage of SREBP-1a by H2O2 was also observed even in the presence of RA. These results suggest that H2O2, enhances a cleavage of SREBP-1a precursor protein, which independently occurs with the RA suppression of SREBP-1a gene expression, and that RA itself has no role in the SREBP-1a activation in adipocytes.

Seasonal incidence of lameness and risk factors associated with thin soles, white line disease, ulcers, and sole punctures in dairy cattle

Lameness is a multifactorial condition with many causes. In this study, cow lifetime records were used to quantify the incidence of specific lameness-causing lesions and investigate factors associated with those lesions. Of primary interest were the effects of seasonality and the effects of thin soles (TS). Thin sole-induced toe ulcers (TSTU) occurring adjacent to the white line in the apical portion of the weight-bearing surface were distinguished from white line disease (WLD) occurring in the region of the abaxial heel sole junction. Sole (SU), heel (HU), and toe (TU) ulcers; TS; sole punctures (SP); leg injuries (INJ); and other (OTH) lesions (e.g., infectious diseases, laminitis, unclassified hemorrhage) were also considered. Data were collected from May 2004 through October 2007 and included records for 4,915 cows of which 1,861 had at least one recorded lameness event. Of these, 20% were TSTU, 20% OTH, 16% SU, 13% TS, 10% WLD, 8% HU, 6% INJ, 4% SP, and 2% TU. Annual incidence risk for lameness was 49.1%. Overall incidence rate for lameness was 1.41/1,000 cow-days, and rates for all lesions were highest in the summer. As parity increased, so did incidence rates for TS, SU, WLD, HU, and INJ. For TS, TSTU, and WLD, incidence rates were lowest in early lactation (16 to 60 DIM), whereas for SU, HU, TU, incidence rates were highest in mid lactation (61 to 150 DIM). Cox proportional hazard models for TS, TSTU, WLD, SU, HU, TU, and SP included age and year of first calving and milk production capacity. Prior/concurrent lameness events, season, parity, and stage of lactation were included as time-dependent effects. Prior/concurrent TS increased the hazard for all other lesions, particularly TSTU, and HU. Having any other prior claw lesion also increased the hazard for all lesions. Hazard was highest in summer for all lesions except TU. Stage of lactation was a significant effect in hazard of TSTU, which was lowest in mid lactation (61 to 150 DIM).

The development, implementation and testing of a lameness control programme based on HACCP principles and designed for heifers on dairy farms

This paper describes the development and testing of a lameness control programme (LCP) for heifers on dairy farms. The LCP, which is based on the analysis of hazards and critical control points (HACCP), was tested via a randomised intervention study on 60 farms. Tangible hazards for each farm were identified, allotted to 11 categories of proximate hazard and scored on each farm to quantify the risks presented by each hazard. Feet were inspected for signs of claw horn disease and infection, such as digital dermatitis. Intervention was generally ineffective, primarily through failure to implement the LCP. However, retrospective analysis was able to demonstrate highly significant associations between risks attached to proximate hazards and probabilities of lameness and foot lesions, allowing the severity of these hazards to be ranked. The most significant proximate hazards of environmental origin were prolonged standing on concrete, standing in wet slurry and factors that cause claw trauma. The most severe proximate hazards however were those associated with failures of management, especially poor claw condition and inadequate foot care. Overall farm risks (OFR) were estimated by summing the products of the generic severity for proximate hazards with on-farm risks. Changes in OFR were significantly related to changes in outcome (lameness and lesions).

Effect of relocation on locomotion and cleanliness in dairy cows

This study was conducted to determine the effect that relocation to a new free stall barn had on locomotion and cleanliness of two breeds of dairy cows. The original facility before relocation had cows housed in an 8-row free stall barn. Cows were allocated in a new 4-row free stall facility: cows of two breeds (n=22 Holsteins and 22 Jerseys) were intermixed in the northwest section. Locomotion (scale 1-5) and cleanliness were scored (scale 1-4). Holsteins and Jerseys had no difference in locomotion score throughout 12 weeks following relocation. A lactation number by date interaction showed cows in third and greater lactations had significantly higher locomotion scores (more lameness) by day 86. Locomotion scores increased across breeds during the 86-d observation period, suggesting cows became lamer. Jerseys had cleaner lower legs than Holsteins (2.9+/-0.1 v. 3.5+/-0.1, respectively). Lactation number affected lower leg cleanliness, with scores decreasing as lactation number increased (3.4 v. 3.3 v. 2.9+/-0.10 for first, second and third and greater lactations, respectively; P<0.01). All cows were cleaner (lower scores) after relocation, suggesting that the new facility improved hygiene.

Septic Arthritis of the Distal Interphalangeal Joint in Cattle: Comparison of Digital Amputation and Joint Resection by Solar Approach

OBJECTIVE

To determine in cattle with septic arthritis of the distal interphalangeal joint (SADIJ) the efficacy of resection of the distal interphalangeal joint (JRES) as a digit salvage technique compared with digital amputation (DAMP).

STUDY DESIGN

Prospective, randomized clinical study.

ANIMALS

German Holstein-Friesian dairy cattle with SADIJ of 1 hind limb (n=52).

METHODS

SADIJ diagnosis was based on clinical examination and radiography. Cows were randomly assigned with owner consent to DAMP (n=26) or JRES (n=26). After JRES, a wooden block was fixed to the partner claw in combination with a tipping claw prophylaxis.

RESULTS

After surgery, degree of lameness improved significantly faster after DAMP than after JRES. New claw diseases in the opposite limb occurred more frequently after JRES (n=6) than after DAMP (n=1). New claw defects developed in the partner claw on the operated limb in 6 cows after DAMP compared with 1 after JRES. Tipping claw was observed in 50% of JRES cows at day 180. Mean life span between groups was not significantly different (DAMP=13.5 months, JRES=10.9 months).

CONCLUSION

Higher surgical and postsurgical expenditures for JRES were not counterbalanced by a longer productive life; however, frequent disease of the partner claw of cows after DAMP should be considered a critical point, as this generally leads to culling.

CLINICAL RELEVANCE

The higher expenditure for JRES can be justified only for young, valuable cattle.

An Evaluation of the Seasonality of Veterinary Treatments for Lameness in UK Dairy Cattle

Of the 4 main diseases causing lameness in UK dairy cattle, 2 (digital dermatitis and foul-in-the-foot, or interdigital necrobacillosis) are infectious diseases that are commonly associated with similar underfoot conditions, and 2 (sole ulcer and white-line disease) result from subclinical laminitis. Comparison of the seasonality of these 2 diseases can identify whether their own unique risk factors are more important than the risk factors they share. Using a database from 46 veterinarians distributed across the United Kingdom, the seasonality of treatments for these 4 diseases was evaluated. This analysis showed that the seasonality of lameness in UK dairy cattle was significantly reduced in comparison with previous reports from the 1980s. This was primarily due to 1) a reduction in the seasonality of digital dermatitis (outbreaks of which accounted for 6.7% of veterinary reports), with only 60% of reports during the winter as opposed to 72% in earlier studies, and 2) a change in the seasonality of white-line disease from a disease that was most commonly seen in the winter (55% of reports) to a disease that was most commonly reported in the late summer or early autumn, with significantly more reports in August and October than in February. Comparison of the seasonality of digital dermatitis and foul-in-the-foot showed a significant difference in the seasonality of the 2 diseases, with foul-in-the-foot being significantly more common compared with digital dermatitis in June and August. This implies that significant risk factors exist for digital dermatitis that are not as important for foul-in-the-foot. The difference in the seasonality of sole ulcer and white-line disease was even more marked, with white-line disease being significantly more common than sole ulcer from August to October, despite these diseases being more closely linked in the literature than digital dermatitis and foul-in-the-foot. This comparison shows that the seasonality of lameness has changed in the United Kingdom and that white-line disease has significantly different risk factors than sole ulcer.

A case study of lameness in three dairy herds

All cases of lameness that occurred in cows from three dairy herds between August 198'3 and July 1990 were examined every 2 weeks from the onset of lameness until the lesions resolved. The incidences of herd lameness were 38%, 22% and 2%. Some 186 clinical lesions were identified in 134 cases of lameness in 120 cows. Sole bruising (42%) and white line separation (39%) were the most frequently diagnosed conditions. Lateral digits of the hind limbs were the most affected. The mean time from the onset of lameness to clinical recovery was 27 days and to lesion recovery was 35 days. The peak incidence of lameness occurred during winter for autumn-calving cows and during the late spring for spring-calving cows. The onset of lameness was associated with the stage of lactation and wet weather conditions. Survival analysis revealed that the probability of an individual cow lasting in the milking herd for any specified period of time without becoming lame was highly associated with both her herd environment and her age. Total lactation yields of milk, milk fat and milk protein were lower for cows suffering from lameness than for herd-mates matched on age and proximity on calving date (P<0.05). Reproductive performance was also poorer in lame cows than in their herd-mates.

Effect of Lameness on Culling in Dairy Cows

The purpose of this study was to assess the effect of lameness on dairy cow survival. Cox's proportional hazards regression models were fitted to single-lactation data from 2520 cows in 2 New York State dairy herds. Models were controlled for the time-independent effects of parity, projected milk yield, and calving season, and for the time-dependent effects of lameness and culling. Other common diseases were found to be nonconfounding and so were not included in any of the final models. Survival was measured as the time from calving until death or sale. Cows were censored if they reached the start of the next lactation or end of the study, whichever occurred first. All models were stratified by herd. For all lameness diagnoses combined, survival in the herd decreased for those cows becoming lame during the first half of lactation, with a hazard ratio of up to 2 times that of a nonlame cow. Foot rot diagnosed during the second or third months of lactation decreased survival during the same time period (hazard ratio=5.1; 95% confidence interval=1.6 to 16.2). Sole ulcers diagnosed in the first 4 mo of lactation decreased survival in several subsequent periods in which the strongest association was between diagnosis in the third and fourth months of lactation and exit from the herd during that same period (hazard ratio=2.7; 95% confidence interval=1.3 to 6.0). Foot warts were not associated with decreased survival in this analysis. Lameness was never associated with increased survival in any of the models.

Claw Hardness of Dairy Cows: Relationship to Water Content and Claw Lesions

Lameness of dairy cows is a major welfare and economic problem. Degree of hardness of claws may influence chances for injury or for claw lesions, and exposure of claws to moisture may make them soft. To assess the relationship among hardness of the claw horn, quantity and rate of absorption of water, and incidence of claw lesions, 4 experiments were carried out. In the first 3 experiments, we soaked pieces of the claw horn in water for 12 to 24 h. Soaked claws gained weight and became significantly softer, indicating that water was absorbed. One-third of the total water absorbed in 24 h occurred during the first hour. Base of the abaxial and dorsal walls of the claw was harder than the sole, but became softer more rapidly when soaked in water. In the 4th experiment, significant negative correlations were detected between claw hardness of cows and severity of claw lesions, suggesting that cows with softer claws have the most severe claw lesions. Claw horn tissue absorbs water rapidly and claw hardness decreases with moisture content, suggesting that brief exposures to moist surfaces result in claws that absorb water and consequently become softer. The relationship between hardness and claw lesions indicates that cows with softer claws are at greater risk for lameness.

Prevalence of lameness among dairy cattle in Wisconsin as a function of housing type and stall surface

OBJECTIVE

To determine the prevalence of lameness as a function of season (summer vs winter), housing type (free stalls vs tie stalls), and stall surface (sand vs any other surface) among lactating dairy cows in Wisconsin.

DESIGN

Epidemiologic survey.

ANIMALS

3,621 lactating dairy cows in 30 herds.

PROCEDURE

Herds were visited once during the summer and once during the winter, and a locomotion score ranging from 1 (no gait abnormality) to 4 (severe lameness) was assigned to all lactating cows. Cows with a score of 3 or 4 were considered to be clinically lame.

RESULTS

Mean +/- SD herd lameness prevalence was 21.1 +/- 10.5% during the summer and 23.9 +/- 10.7% during the winter; these values were significantly different. During the winter, mean prevalence of lameness in free-stall herds with non-sand stall surfaces (33.7%) was significantly higher than prevalences in free-stall herds with sand stall surfaces (21.2%), tie-stall herds with non-sand stall surfaces (21.7%), and tie-stall herds with sand stall surfaces (12.1%).

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that the prevalence of lameness among dairy cattle in Wisconsin is higher than previously thought and that lameness prevalence is associated with season, housing type, and stall surface.

The impact of clinical lameness on the milk yield of dairy cows

This paper investigates the impact of lameness on milk yield. The dataset includes approximately 8000 test-day milk yields from 900 cows on five farms in Gloucester, UK, collected over 18 mo from 1997 to 1999. The data were structured to account for repeated measures of test-day yield (1 to 10 per cow) and analyzed to account for this autocorrelation. Factors affecting milk yield included: farm of origin, stage of lactation, parity, and whether a cow ever became lame. In clinically lame cows, milk yield was reduced from up to 4 mo before a case of lameness was diagnosed and treated and for the 5 mo after treatment. The total mean estimated reduction in milk yield per 305-d lactation was approximately 360 kg. We conclude that clinical lameness has a significant impact on milk production. This is important information for assessing the economic impact of clinical lameness and its impact on cow health. It adds weight to the importance of early identification of clinical lameness and the urgency of techniques to improve the definition of this highly subjective diagnosis.

Fenestration of the abaxial hoof wall and implantation of gentamicin-impregnated collagen sponges for the treatment of septic arthritis of the distal interphalangeal joint in cattle

A novel surgical approach to the distal interphalangeal joint of cattle, through the abaxial hoof wall, for the treatment of septic arthritis is described. In seven cattle a rectangular piece of horn (15 x 40 mm) was excised from the abaxial hoof wall and the joint was lavaged with Ringer's solution. Infected and/or necrotic tissue was removed from the joint and gentamicin-impregnated collagen sponges were introduced. The piece of horn was reattached, a rubber block was glued to the contralateral claw, and a bandage applied. Aftercare consisted of changes of bandage, systemic administration of antimicrobial drugs and box rest. At follow-up, six of the cattle were sound but one cow which had been slaughtered five months after surgery had remained slightly lame.

Osseous sequestration in cattle: 110 cases (1987-1997)

OBJECTIVE

To determine risk factors for development of sequestra in cattle and identify factors associated with a successful outcome.

DESIGN

Retrospective study.

ANIMALS

110 cattle.

PROCEDURE

Medical records of cattle treated at veterinary teaching hospitals in North America were reviewed. To determine risk factors for osseous sequestration, breed, age, and sex of cattle with osseous sequestration were compared with breed, age, and sex of all other cattle admitted during the study period.

RESULTS

110 cattle were included in the study. Three had 2 sequestra; thus, 113 lesions were identified. Most sequestra were associated with the bones of the extremities, most commonly the third metacarpal or third metatarsal bone. Ninety-two animals were treated surgically (i.e., sequestrectomy), 7 were treated medically, 3 were initially treated medically and were then treated surgically, and 8 were not treated. Follow-up information was available for 65 animals treated surgically and 6 animals treated medically. Fifty-one (78%) animals treated surgically and 5 animals treated medically had a successful outcome. Cattle that were 6 months to 2 years old had a significantly increased risk of developing a sequestrum, compared with cattle < 6 months old. Cattle in which sequestrectomy was performed with the aid of local anesthesia were significantly more likely to undergo 2 or more surgical procedures than were cattle in which sequestrectomy was performed with the aid of general anesthesia.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that sequestrectomy will result in a successful outcome for most cattle with osseous sequestration.

Digital characteristics in commercial dairy herds fed metal-specific amino acid complexes

Five commercial dairy herds in Central New York fed metal-specific amino acid complexes were selected to evaluate digital characteristics. During the first year (period 1), herds were evaluated by a specific procedure by one individual. Three herds were not supplemented and two herds were supplemented with zinc methionine. During the subsequent year (period 2) all herds were switched to a combination of zinc methionine, copper lysine, manganese methionine, and cobalt glucoheptonate and evaluated in the same way as during period 1. There was no effect of period on incidence of heel erosion and interdigital dermatitis. During period 2, there was a reduced incidence of double soling, white line separation, sole hemorrhages, sole ulcers, and papillomatous digital dermatitis, and the incidence of wall ridges tended to be reduced compared with period 1. There was no effect of period on the incidence of abaxial wall lesions, digital arthritis, or foot rot, although the overall incidence of these disorders was low. During period 2, when cows were fed a combination of complexed trace minerals, there was a general reduction in the incidence of digital disorders associated with the laminitis syndrome complex compared with period 1; however, other time-related differences existed that may confound interpretation.

The influence of long-term supplementation with biotin on the prevention of lameness in pasture fed dairy cows

In a double-blind study, the influence of biotin supplementation on lameness in dairy cows was investigated over a 13-mo period. The experimental site was a tropical upland environment and involved over 2705 Holstein and Friesian cows on 20 participating farms. Cows on 10 farms received biotin at a rate of 20 mg/head per day in the concentrate, and cows on 10 other farms received feed without the biotin supplement. Premixes with or without biotin were incorporated into a grain concentrate that was fed at a constant rate to cows at milking. Farmers maintained accurate records of the nature of hoof problems and any treatment applied. Each herd was evaluated for locomotion scores at 8-wk intervals. Locomotion scores were significantly correlated with the number of days with measurable rainfall per month (r = 0.88). The biotin-supplemented herds exhibited better locomotion scores than the unsupplemented herds. In the wet summer period the number of lame cows, as observed by the farmer, were significantly fewer during the rainy period for the biotin-supplemented herds and required fewer antibiotic treatments than unsupplemented herds. Most hoof lesions were most commonly observed in the outer claws of the hind limb. Daily milk production (17.3 vs. 18.5 L) was not affected by biotin supplementation. Reduced milk fat percentage and somatic cell counts of bulk milk were recorded in the biotin supplemented herds during the wet, summer period.

Bovine acidosis: implications on laminitis

Bovine lactic acidosis syndrome is associated with large increases of lactic acid in the rumen, which result from diets that are high in ruminally available carbohydrates, or forage that is low in effective fiber, or both. The syndrome involves two separate anatomical areas, the gastrointestinal tract and body fluids, and is related to the rate and extent of lactic acid production, utilization, and absorption. Clinical manifestations range from loss of appetite to death. Lactic acid accumulates in the rumen when the bacteria that synthesize lactic acid outnumber those that utilize lactic acid. The systemic impact of acidosis may have several physiological implications, including laminitis, a diffuse aseptic inflammation of the laminae (corium). Although a nutritional basis for the disease exists, etiology includes a multitude of interactive factors, such as metabolic and digestive disorders, postpartum stress, and localized trauma, which lead to the release of vasoactive substances that trigger mechanisms that cause degenerative changes in the foot. The severity of laminitis is related to the frequency, intensity, and duration of systemic acidotic insults on the mechanisms responsible for the release of vasoactive substance. The critical link between acidosis and laminitis appears to be associated with a persistent hypoperfusion, which results in ischemia in the digit. Management of acidosis is critical in preventing laminitis. High producing dairy herds attempting to maximize energy intake are continually confronted with subclinical acidosis and laminitis. Management of feeding and husbandry practices can be implemented to reduce incidence of disease.

Incidence and prevalence of lameness in dairy cattle

A survey was made of 37 dairy farms in Wirral, mid-Cheshire, mid-Somerset and Dyfed, Wales, to assess the incidence and prevalence of lameness in the cows between May 1989 and September 1991. The incidence was obtained from records made whenever a cow was examined for lameness or received preventive foot-trimming. The mean annual incidence was 54.6 new cases per 100 cows with a range from 10.7 to 170.1 and the mean values during summer and winter were 22.9 and 31.7, respectively. The prevalence of lameness was measured by regular visits at which locomotion was scored on a scale of 1 to 5, and the prevalence of lameness was calculated for each visit as the proportion of cows with scores of 3 or more. The mean annual prevalence over the whole period was 20.6 per cent with a range from 2.0 to 53.9 per cent for the 37 farms. The mean prevalences during summer and winter were 18.6 and 25.0 per cent, respectively. The prevalence measured at a single visit in midsummer or midwinter was significantly correlated with the mean prevalence over the whole corresponding period and may be useful as an assessment of the extent of lameness in a herd and the efficacy of control measures. There was evidence that training farmers to recognise early cases of lameness and request veterinary treatment resulted in a marked reduction in the duration of cases of lameness.

Claw conformation of dairy heifers in two management systems

A computerized conformation determination system was used to evaluate objectively claw conformation of dairy heifers in two management systems, i.e., housed indoors on concrete slats or out of doors in a dry lot. Examinations were made at 4-week intervals from 12-13 months of age until calving at 24-26 months. Overall, the angle of the dorsal border did not differ between front and hind claws. Length of the dorsal border, heel height, and toe:heel ratio were greater for front claws (P < 0.001). Hind claws were longer than front claws (P < 0.001), but front claws were wider (P < 0.001). On both front and hind limbs, lateral claws were wider than medial claws (P < 0.001). Angles of the dorsal border decreased, but lengths of the dorsal border and heel heights increased over time (P < 0.05). Significant differences in claw conformation were found between the two management groups. Heifers maintained out of doors had longer toes and wider lateral claws than heifers housed indoors (P < 0.05). At time of entry into the respective management group, no significant differences in claw traits were found between the two groups. At calving, however, out-door-housed heifers had hind claws with smaller dorsal angles and longer dorsal borders (P < 0.05).

Surgical management of digit disorders in cattle

Digital diseases in cattle are common. Cattle affected by digital disorders do not always respond to medical therapy and often need surgery. A thorough examination of the digits and radiographic evaluation help the clinician to choose the appropriate treatment and surgical approach. Age, sex, weight, type of production, and environment of the cattle also should be considered in choice of therapy.

Lesions associated with subclinical laminitis of the claws of dairy calves in two management systems

Claws of ten 6 to 7-month-old dairy calves in two management systems were examined for lesions associated with subclinical laminitis. Sole haemorrhages were found only in claws of calves maintained out of doors. No significant differences in number and severity of haemorrhages were found between left and right or lateral and medial claws, but haemorrhages were more frequent and more severe in hind claws than in front claws (P < 0.05). More haemorrhages of greater severity were present in the white zone at the toe than in all other areas of the weight-bearing surface combined (P < 0.05). No lesions of interdigital dermatitis and heel horn erosion were found in either indoor-housed or outdoor-housed calves. All calves kept indoors on deep bedding developed overgrown claws.

Structural characteristics of the bovine claw: horn growth and wear, horn hardness and claw conformation

Claw quality is the product of horn characteristics, claw shape and anatomy and physiology of the inner structure. This paper aims to review some of the different approaches that have been employed to evaluate claw quality. The various factors that may influence horn growth and wear are reviewed, including physiological, seasonal, nutritional, environmental, management and anatomical aspects. Horn hardness is similarly described. Claw conformation is discussed, commencing with a brief outline of the various methods used to determine claw shape and size, followed by an account of some of the factors that influence claw conformation. The clinical importance of claw conformation in cattle is considered with particular reference to lameness, longevity and production traits. Finally, the prospect of improving claw quality by selection of bulls based on claw measurements is reviewed.

Observer variation in field data describing foot shape in dairy cattle

A qualitative scoring method was devised to describe foot shape in dairy cattle, which relied solely on visual observations. Four independent trained observers used the method to assess the foot shape of 248 cows located on three farms on two different occasions, and the percentages of agreement and near-agreement for intraobserver and interobserver variation on scores for foot shape were calculated. Score assessment methods were suitable for describing features with a broad variation within one score value; reducing the number of observers did not improve best agreement between separate observations by more than 80 per cent.

“Subclinical” laminitis in dairy cattle

In dairying countries worldwide, the economic importance of lameness in cattle is now recognised. Laminitis is regarded as a major predisposing factor in lameness caused by claw disorders such as white zone lesions, sole ulcer, and heel horn erosion. The existence of subclinical laminitis was first suggested in the late 1970s by Dutch workers describing the symptoms of sole haemorrhages and yellowish-coloured, soft sole horn. In an attempt to clarify some of the confusing and often conflicting terminology, the literature on laminitis is reviewed. Disturbed haemodynamics, in particular repeated or prolonged dilation of arteriovenous anastomoses, have been implicated in the pathogenesis of both equine and bovine laminitis. Some characteristics of the vascular system of the bovine claw which may be of importance in the pathophysiology of the subclinical laminitis syndrome are therefore discussed. Clinical observations suggest that subclinical laminitis is a multifactorial disease. The different factors that are or may be involved in its aetiology vary in complexity and severity according to the management protocol of the animals. The possible involvement of subclinical laminitis in claw lesions is assessed.

A longitudinal study of the hooves of non-lame cows

A longitudinal study of the feet of cows from a seasonal dairy herd was conducted over a 12 month period to measure the occurrence of subclinical hoof lesions. Eleven 2-year-old cows, entering the herd for the first time, and eleven mature cows were randomly selected from a herd of 415 cows at the end of winter (July 1989) prior to calving. The incidence of lameness in the herd over the 12 months was 2%. None of the trial cows became lame during the study. Cows were examined monthly. The type, severity and location of any hoof lesions were recorded. Sole haemorrhage, erosion of the heel bulb and minor white line separation were the most commonly observed lesions. These lesions were observed with specific claw distributions in the cow and at specific times of the year and breeding season, with waves of each type of lesion passing through the herd at a particular time. White line separation was observed commonly during spring (up to 37% of digits affected), disappeared almost completely over the dry summer months and reappeared in autumn, increasing to 40%' again over winter. Lesions were more commonly observed in the lateral digits, with fore feet being more commonly affected than hind feet. Erosion of the heel bulbs was common in August (65% of digits affected, more common in mature cows than 2-year-olds), disappeared quickly during spring, and reappeared in all cows during the following winter (88% of digits; no age differences). There were no differences in distribution between digits. Sole haemorrhages were concentrated over the mid-sole and abaxial sole zones. They were more common in the hind feet than the front feet and more common in the outside claws (p < 0.001). Haemorrhages were not observed prior to or soon after calving, appeared in October and reached a peak of 40% in December, then gradually disappeared by the time of drying-off in May. The 2-year-olds were more frequently affected than the mature cows (p <0.001).

Sole ulcers in dairy cattle: associations with season, cow characteristics, disease, and production

Epidemiological associations, expressed as odds ratios between variables obtained from dairy cow records and sole ulcer occurrence at claw trimmings were estimated with logistic regression analysis on data from 2204 and 1124 cows in lactation 1 and lactations 2 to 9, respectively. Sole ulcer in one foot or more than one foot occurred in 20.0 and 29.7% of cows in lactation 1 and in 23.5 and 24.7% of cows in lactations 2 to 9. The analysis revealed several complicated interactions. Trimming or calving in summer to fall was strongly associated with sole ulcer. Trimming later than 1 to 2 mo after calving was positively associated with sole ulcer depending on milk yield, body weight, or season of calving. If lactation 1 cows were treated for disease (limb, metabolic, digestive, or severe reproductive disorders), sole ulcer in more than one foot occurred earlier in lactation. Milk yield in early lactation and body weight were positively associated with sole ulcer. Heel erosion was associated with sole ulcer depending on season of trimming and parity. Presence of sole ulcer but not heel erosion in a lactation increased the risk of sole ulcer in the subsequent lactation. The interval between trimmings appeared to be important.

Lesions causing lameness requiring veterinary treatment in pasture-fed dairy cows in east Gippsland

In 653 mature dairy cows examined for lameness between February 1987 and July 1988 there were 783 lesions identified. Most of these were located below the pastern (90.5%) and most lesions involved hindlimbs (79%). Of digital and interdigital lesions, hind limbs had the most lesions (69.2%). Medial digits of forelimbs were least affected (7.8%) and lateral digits of hindlimbs were the most affected (44.4%). Lateral digits of forelimbs were slightly more affected than medial digits of hindlimbs (17.0% vs 14.8%). Ten different types of lesions contributed to 84.5% of foot lameness. Most common were axial wall cracks (21.7%), underrun sole (14.6%), footrot (13.0%), punctured sole (9.3%) and white line disease (7.2%). Age, rainfall and the early lactation period were factors determining the incidence of lameness.

The incidence, cost and factors associated with foot lameness in dairy cattle in south-western Victoria

A survey of 73 dairy farms in south-western Victoria was conducted to assess the cost and mean herd incidence of foot lameness for the period from calving to the end of November, 1985, and to identify the herd, management and environmental factors associated with foot lameness. The mean herd size was 125 cows (range 82 to 220). Lameness occurred in 64 (88%) herds, and the mean herd incidence was 7.0% (range 0.0 to 30.9%). The main clinical signs associated with lameness were the presence of overworn and/or bruised soles, or stones lodged in the interdigital cleft. Factors associated with lameness were: property and herd size, age of cow, bail feeding, voluntary entry into the bails, and features of the farm track including its length, the presence of steep slopes, the type of surface material, presence and treatment of broken sections and maintenance including rolling history. The association of these factors with specific clinical signs was examined. The mean cost was estimated to be $42.90 per lame cow due to loss of production, treatment, the culling or death of lame cows, and extra man hours spent managing lame cows. It was concluded that the site, construction, maintenance and use of the farm track were of major importance to the incidence of lameness in herds in this area and recommendations for reducing lameness are made.

Incidence of lameness requiring veterinary treatment in dairy cattle in Queensland

A survey of the incidence of lesions causing lameness in dairy cattle was conducted by veterinarians in 9 practices in Queensland between November 1984 and July 1985. One hundred and eighty five cases were treated in 83 dairy herds. The average incidence of lameness which required treatment by veterinarians was 2.7 cases per 100 cows per 9 months, with a range of 1.4 to 5.5% in the 9 practices. Foot lesions constituted 83.2% of all lesions; the most common being interdigital necrobacillosis (15%), deep sepsis (8.9%), white line disease (8.4 per cent), axial groove fissure (8.4%), bruised sole (5.6%) and foreign body in the sole/heel (5.6%). Sixty-five per cent of foot lesions occurred in the hind feet and 63% of these lesions occurred in the lateral claw, while 37% of foot lesions occurred in abnormally shaped claws. Limb lesions accounted for the remaining 16.8% of lesions, and 50% of these lesions occurred in the hip and stifle, while trauma was the main cause of limb lesions.