Prevalence and distribution of foot lesions in finishing pigs in south-west England

Occurrence of claw asymmetries in fattening pigs and potential impact on the development of sole ulcerations

Background

Claw abnormalities, particularly claw asymmetries, are associated with lameness in pigs and can be a welfare issue. However, the prevalence and development of claw asymmetries in pigs of different age is unknown. Therefore, the aim of this study was to analyze the claw symmetry over the pig lifetime from birth to slaughter as well as the occurrence of sole ulcerations in fattening pigs possibly caused by such asymmetric claws.

Results

From third day of life until slaughtering, asymmetric growth of the claws was detected more frequently and more severely with increasing age as determined by three-step scoring. Sole ulcerations were detected in slaughtered pigs only with a prevalence of 64.2% (197/307 examined animals). The risk for a sole ulceration was 3.6-fold higher for pigs with strongly asymmetric claws (≥ 30% size difference of the claw footing area) compared to slightly asymmetric claws (≥ 5–15% size difference of the claw footing area) (odds ratio (OR) = 3.6). It was even higher for pigs showing intermediately asymmetric claws (≥ 15–30% size difference of the claw footing area) (OR = 2.7).

Conclusions

The study showed a significant increase in the prevalence of claw asymmetries over the pigs’ lifetime, which can lead to serious pathologic findings with increasing age such as sole ulcerations. Most likely, the unbalanced weight load on single claws in combination with hard flooring can result in claw damages. Moreover, a genetic component cannot be excluded because claw asymmetries were already detected in suckling piglets.

Size-related changes in foot impact mechanics in hoofed mammals

Foot-ground impact is mechanically challenging for all animals, but how do large animals mitigate increased mass during foot impact? We hypothesized that impact force amplitude scales according to isometry in animals of increasing size through allometric scaling of related impact parameters. To test this, we measured limb kinetics and kinematics in 11 species of hoofed mammals ranging from 18-3157 kg body mass. We found impact force amplitude to be maintained proportional to size in hoofed mammals, but that other features of foot impact exhibit differential scaling patterns depending on the limb; forelimb parameters typically exhibit higher intercepts with lower scaling exponents than hind limb parameters. Our explorations of the size-related consequences of foot impact advance understanding of how body size influences limb morphology and function, foot design and locomotor behaviour.

A cross-sectional study of prevalence and risk factors for foot lesions and abnormal posture in lactating sows on commercial farms in England

A cross-sectional study of lactating sows in 71 commercial pig herds in England was carried out to estimate the prevalence of foot lesions and abnormal posture and investigate the associated risks. Observational data were collected on the standing posture, lesions on the hind left foot, and the pen the sow was housed in for 233 sows. The prevalence of foot lesions was 76.8% and 10.8% of lactating sows had abnormal posture. Sows housed on slatted floors during pregnancy had an associated increased risk of heel flaps but a reduced risk of toe erosion, compared with sows housed on solid concrete floors with bedding during pregnancy. There was an increased risk of abnormal posture in lactating sows housed on slatted floors during pregnancy compared with those housed on solid concrete floors with straw bedding during pregnancy. In addition, there was an increased risk of abnormal posture in lactating sows with wounds on the limbs and erosions on the toe and the heel/sole. The positive association between abnormal posture and foot lesions suggests that these lesions might be painful. Housing sows on solid floors during pregnancy might reduce the risk of abnormal posture, and certain foot lesions, in sows during lactation. However, posture is a less sensitive measure of lameness than gait, and the nature of the causal relationship between foot lesions and lameness requires further investigation.

A cross-sectional study of the prevalence of foot lesions in post-weaning pigs and risks associated with floor type on commercial farms in England

We carried out a cross-sectional study during 2003 and 2004 to establish the prevalence and risk factors associated with floor type for commonly observed foot lesions in pigs aged 6, 8 and 14 weeks. The overall prevalence of foot lesions was 39.6% in 2283 pigs from 90 representative pig farms in England. The most prevalent lesions were heel/sole bruising (7.1%), heel/sole erosion (10.8%), heel flaps (8.4%) and toe erosion (11.6%). Pigs were kept on either solid (41%), partly slatted (28%) or fully slatted (31%) floors. Of the 104 pens with a solid floor, 26% of pens were outside with straw bedding on a soil base, 33% were indoors with deep bedding on solid concrete, 25% were partly deeply bedded on solid concrete and 16% were sparsely bedded on solid concrete. Only six of the pens with partly slatted floors were bedded. Multilevel logistic-regression models were built using data from 100 farms to examine the risks for individual foot lesions with prevalences >5%. The prevalence of toe erosions was positively associated with deep bedding, whereas deep bedding and soil floors were negatively associated with the prevalence of heel/sole erosions. Heel flaps and heel/sole bruising were both associated with slatted floors, possibly indicating a common aetiology. The greatest reduction in prevalence of all these lesions, from AFp calculations, would be achieved by moving pigs from slatted floors onto solid floors.

An object-oriented Bayesian network modeling the causes of leg disorders in finisher herds

The implementation of an effective control strategy against disease in a finisher herd requires knowledge regarding the disease level in the herd. A Bayesian network was constructed that can estimate risk indexes for three cause-categories of leg disorders in a finisher herd. The cause-categories of leg disorders were divided into infectious causes (arthritis caused by infectious pathogens), physical causes (e.g. fracture and claw lesions), and inherited causes (osteochondrosis). Information about the herd (e.g. the herd size, floor type and number of suppliers) and information about individual pigs (e.g. results from diagnostic tests) were used to estimate the most likely cause of leg disorders at herd level. As information to the model originated from two different levels, we used an object-oriented structure in order to ease the specification of the Bayesian network. Hence, a Herd class and a Pig class comprised the basic components of the object-oriented structure. The causal structure of the model was based on evidence from published literature. The conditional probabilities used in the model were elicited from experts within the field and from the published literature. To illustrate the behaviour of the model, we investigated the value of different levels of evidence in two fictitious herds with different herd characteristics related to the risk of leg disorders (e.g. purchase policy, production type and the stocking density in pens). The model enabled us to demonstrate the value of performing systematic collection of additional information (i.e. clinical, pathological and bacteriological examination) when identifying causes of leg disorders at herd level.

Osteochondrosis/osteoarthrosis and claw disorders in sows, associated with leg weakness

The objective of this study was to investigate the associations between different leg weakness symptoms and osteochondrosis/osteoarthrosis and claw disorders in sows together with the influence of age on these findings. One hundred and seventeen sows in one herd were followed from 6 months of age until culling and judged for leg weakness once in every gestation using a scale from 1 (normal) to 4 (severe changes). At slaughter changes in joints, growth plates and claws were scored on a scale from 1 (normal) to 5 (very severe changes). Osteoarthrotic changes were strongly associated with osteochondral changes in humeral and femoral condyles. The clinical signs of osteochondrosis and osteoarthrosis were found to be: buck-kneed forelegs, turn out of fore and hind legs, upright pasterns on hind legs, stiff locomotion, lameness and tendency to slip. The clinical signs of claw lesions were found to be: buck-kneed forelegs, upright pasterns, steep hock joints, turn out of hind legs, standing under position on hind legs, stiff movements, swaying hindquarters, goose-stepping hind legs, tendency to slip and lameness. Overgrown claws were strongly associated with leg weakness indicating the need for claw trimming in sow populations.

Foot lesions in finishing pigs and their associations with the type of floor

The associations between individual foot lesions and different types of floor were investigated in 4038 finishing pigs on 21 units. The overall prevalence of foot lesions was 93.8 per cent and the prevalence ranged from 79.4 per cent to 100 per cent on different units. Analysis showed that pigs kept on bedded floors, with either sparse or deep straw, had a lower prevalence of sole erosions, heel erosions and heel flaps and a higher prevalence of white line lesions, false sand cracks, wall separations and toe erosions than pigs kept on bare solid concrete floors. Partially slatted floors were associated with an increased prevalence of heel erosions, heel flaps, white line lesions, wall separations and false sand cracks, and totally slatted floors were associated with an increased prevalence of sole erosions and heel flaps.

Prevalence and risk factors associated with adventitious bursitis in live growing and finishing pigs in south-west England

The prevalence and risk factors associated with adventitious bursitis in 912 growing and finishing pigs, originating from 20 different housing systems in south-west England, were investigated in this study. The overall prevalence of bursal lesions was 63.4%. Bursae were seen at different aspects of the hock: lateroplantar, plantar, medial and point of the hock. The most frequently affected site was lateroplantar (54.4%) followed by plantar (12.5%), medial (2.0%) and finally the point of the hock (0.7%). There was no difference in the proportions of left and right hocks affected. Bursal lesions were seen in pigs from 8 to 28 weeks of age and prevalence increased with age. Also, the longer the period pigs spent in the pen, the more likely they were to have bursitis. After accounting for the effect of herd of origin, bedding which covered the whole pen (OR 0.11) or only the lying area (OR 0.29) was the most important factor which reduced the risk of bursitis. A wet slurry film in the dunging area (OR 1.67) and a difference between the solid area and the concrete slats greater than 3 cm (OR 3.11) were significantly associated with an increased risk of bursal lesions.

Adventitious bursitis of the hock in finishing pigs: prevalence, distribution and association with floor type and foot lesions

The prevalence, severity and distribution of adventitious bursitis were estimated in 3989 finishing pigs from 21 units in south-west England. The overall prevalence of adventitious bursitis was 51.0 per cent and ranged from 10.1 to 84.0 per cent in the different units. Bursae were found on four different aspects of the hock: lateroplantar, plantar, medial and point of the hock (capped hock). The median severity of the bursae at all the different sites was mild (score 1). There was a large variation in the prevalence of different bursal lesions. Lateroplantar bursae (41.8 per cent) were the most prevalent followed by plantar (12.0 per cent), medial (4.8 per cent) and capped hock (3.7 per cent). There was a significant trend in the prevalence of bursitis with floor type; pigs kept on solid concrete floors with deep straw (> 10 cm) had the lowest risk of having bursitis, and the prevalence increased successively when the floors were solid concrete with sparse straw (< 10 cm), semi-slatted and fully slatted. There was a significant association between the presence of bursitis and foot lesions.