Lameness continues to be a substantial welfare concern within our national herd with the latest research indicating that one in three cows are lame at any one time (Griffiths et al, 2018; Randall et al, 2019). Despite a significant drive towards the reduction of lameness over the last 20 years, there is no robust evidence to indicate that the national picture is improving. However, during this time there has been a significant increase in the body of research available surrounding the benefits of adopting ‘early detection and prompt effective treatment (EDPET)’ protocols on farm. Despite this, only a small proportion of the UK's dairy farms are incorporating this into their lameness control programmes. To ensure we control lameness in the longer term it is vital that this is not only more widely adopted, but that each element is undertaken correctly and efficiently to ensure that the potential of this programme is achieved.
Defining lameness
Despite the well documented economic and welfare impacts of lameness, one of the fundamental difficulties continues to be how the farm team define and recognise the behavioural changes associated with lameness. Instead of considering the definition and recognition of lameness as separate factors, they are in fact intrinsically linked. While we can define lameness as changes to a cow's normal gait because of the expression of pain, the understanding and recognition of these signs creates a disparity between actual and perceived levels of lameness.
It is commonly identified that farmers underestimate the levels of lameness in their herds (Whay et al, 2003; Leach et al, 2010) with early research surrounding lameness identifying that the majority of producers could only identify lame cows that showed an obvious limp (Mill and Ward, 1994). Horseman et al (2014) found that the term ‘lame’ was mostly reserved for severely affected cows. These findings combined with the stoic nature of dairy cattle, results in a significant delay in the treatment of lame cows on farm when relying solely on more conventional methods of lameness, such as watching cows during routine management tasks, for example milking (Groenvelt et al, 2014). It highlights the need to dedicate specific time to lameness detection through the use of mobility scoring or validated automated methods to screen cows for early signs of lameness.
To reduce some of the subjectivity surrounding lameness and identify clear points at which a cow should be considered lame and in need of treatment, a number of standardised scoring systems have been developed. Within the UK, the AHDB 0–3 mobility score is the most commonly adopted scoring system in a commercial setting (Figure 1). The four-point scale was developed based on the assessment of gait and postural changes in relation to the presence of foot lesions (O'Callaghan et al, 2003). The scoring system ranges from 0 (perfect mobility) to 1 (imperfect mobility), 2 (impaired mobility/lame) and 3 (significantly impaired mobility/very lame). However, it must not be forgotten that within each score there is also a range in severity, and it is this that is perhaps sometimes difficult to convey to producers. For example, even if a cow just passes the threshold to be identified as a score 2, she is still lame and requires inspection.
While it is common that many farms will mobility score and gather these data for the purposes of animal welfare auditing, only a small proportion take these scores further and use them to inform decision-making around treatment, breeding, and culling. Furthermore, many of the current aligned milk contracts ask for monthly, quarterly or even bi-annual mobility scores, with many other contracts not auditing herd mobility. This approach does not encourage the ‘evidence-based’ approach that the research has provided with regard to EDPET. Instead of seeing mobility scoring as another part of the farm audit it is imperative that we promote its benefit for driving change in lameness levels on the farm. This ultimately has multiple benefits in terms of welfare, productivity and sustainability and crucially, the public perception of the industry.
Defining EDPET
The concept of EDPET as part of lameness management was introduced in 2010 as part of the AHDB Healthy Feet Programme (HFP). The aim of the HFP is to provide a framework around which trained Mobility Mentors can assist farmers in reducing lameness on their farms. The programme is built on four ‘success factors’: low infection pressure; good horn quality and hoof shape; EDPET; and low forces on the feet. EDPET is a cornerstone of the programme and applicable to all farms, regardless of the main cause(s) of lameness.
The protocol has been developed over recent years to promote an optimal regimen which can be easily followed with relevance to the treatment of lameness in the dairy cow. The key underlying principles require protocols to be put in place to identify the earliest stage of disease (in this case very mild lameness) and facilitate the means through which rapid and ‘gold standard’ treatment can be administered (by an external or internal member to the farm team). However, to benefit most from the investment in time and infrastructure to undertake EDPET correctly, it is important that each individual element is undertaken to a high standard (Box 1).
Box 1.The individual components of EDPET
- EARLY DETECTION: fortnightly mobility scoring with supplemental screening for infectious causes of lameness
- PROMPT TREATMENT: within 48 hours of a new score 2 being identified, ASAP if score 3
- EFFECTIVE TREATMENT: new cases of claw horn lesions should be treated with a therapeutic trim, application of a block to the sound claw and a 3-day course of non-steroidal anti-inflammatory drug. Digital dermatitis should be treated with a licenced topical antimicrobial
EDPET: the evidence base
Lameness is a painful condition (Whay et al, 1997) and therefore urgent treatment is a priority on welfare grounds alone. However, numerous studies have demonstrated that any form of delay in treatment will result in a poorer treatment outcome (Groenvelt et al, 2014; Thomas et al, 2016). It has also been shown that once a cow has become lame, she is predisposed to repeated future cases of lameness and it is these cases that drive the prevalence of lameness in the herd and contribute significantly to lameness incidence (Groenvelt et al, 2014; Randall et al, 2018a). Furthermore, there is the potential for interventions such as preventive hoof trimming to be less effective in preventing future lameness when a cow has a history of lameness events (Daros et al, 2019).
Early detection: mobility scoring
Groenevelt et al (2014) implemented a study that found with the implementation of fortnightly lameness scoring and treatment, the prevalence of lameness decreased. In line with this decrease was an improvement in lesion severity; the treatment group (which received fortnightly lameness scoring and treatment) had fewer sole ulcers and white line disease in comparison to those animals in the control group (which were subjected to the normal on-farm treatment protocol). Studies by Thomas et al (2015, 2016) supported these findings with cows that had been lame for at least 6 weeks having a significantly reduced chance of being sound 5/6 weeks after treatment in comparison to cows that had become lame with-in the previous 2 weeks. These findings become more important when we consider that Leach et al (2012) reported that fortnightly mobility scoring detected lameness a median 65 days earlier than normal farm detection protocols.
Once an animal has been identified as lame, for a treatment to be deemed as ‘effective’ it must achieve a high cure rate. While there is a limited evidence base surrounding treatment, there is sufficient research to support the current best practice recommendation for the treatment of new cases of lameness involving a claw horn lesion (CHL; sole bruise, sole ulcer or white line lesion). This involves a combination treatment consisting of a therapeutic trim, application of a block and administration of 3 days of non-steroidal anti-inflammatory drugs (NSAIDs).
This recommendation is based on the results of a randomised controlled trial which was conducted to test the efficacy of different treatment protocols with respect to improving the mobility of newly lame animals suffering from CHLs (Thomas et al, 2015). The definition of a ‘new case’ was a cow that had a low score (< score 2; AHDB 0–3 scale) at two consecutive fortnightly scores, followed by a high score (≥ score 2). Four different treatments were applied to determine the effectiveness of the application of a block and/or course of NSAID in addition to a therapeutic trim. The treatment outcomes of animals that received a therapeutic trim, block and a 3-day course of NSAIDs had a significantly better ‘cure rate’ than those animals that just received a therapeutic trim (85.4% vs 68.9% respectively using a score of 0 or 1 as a ‘cure’).
It was suggested by Thomas et al (2015) that the possible reason for the results seen was as a result of the role of the NSAIDs in the regression of the CHL, and provision of temporary pain relief to afford the animal a better state of welfare. Newsome et al (2016) then explored the potential role of inflammation in the aetiopathogenesis of CHLs. They linked the formation of new bone on the most caudal aspect of the pedal bone to animals with a history of lameness (Figure 2). The authors of that study proposed that trauma to the corium results in a significant inflammatory response. This localised inflammation is believed to stimulate the formation of these exostoses on the pedal bone. This creates a self-perpetuating cycle of further injury to the corium, which in turn leads to more inflammation and further changes to the pedal bone. The end result is a chronically lame cow.
Newsome et al (2016) suggested that animals respond best to treatment when the EDPET principle is implemented in combination with NSAIDs because of this pathogenic mechanism. They hypothesised that it disrupts the inflammatory aetiology such that if a CHL is detected early and followed by the treatment protocol described by Thomas et al (2015), it may minimise pathological change to the foot (such as exostoses). To prevent the onset of chronic lameness, it is likely that this pathological change to the foot needs to be prevented (or at least minimised) by breaking the chronicity cycle using a combination of EDPET and NSAIDs. At a herd level, fewer repeat cases would impact positively on lameness prevalence.
Although this hypothesis is yet to be proven, it sheds further light on the impact that EDPET can have on farm. Randall et al (2018a) identified that cows with a history of lameness are the key drivers of lameness prevalence on farm and contribute significantly to the number of lameness treatments undertaken. Subsequently Wilson et al (2021) identified that repeated lameness events, or a history of CHL, were associated with a reduced digital cushion volume. Therefore, it is vital that this cycle of chronicity is broken, and while it is also necessary to focus on preventive measures for the longer term, increasing the uptake of EDPET on farm is the current priority in order to have a shorter-term impact on national lameness levels.
Making EDPET work on farm
Fortnightly mobility scoring is the cornerstone of EDPET. As well as identifying new cases of lameness at an early stage it can also allow the mobility status of an animal to be tracked over time. This will allow for trends to be identified (Figure 3), key risk periods to be isolated, and the impact of interventions to be quantified.
However, the key benefit comes from the recognition of lameness at an early stage, and this requires a shift in focus from using scoring as a compulsory auditing assessment to one that will truly benefit the health and welfare of the herd. This requires careful observation of individual cows for the more subtle signs of lameness rather than focusing on those that would be considered more obvious or indicative of a more advanced stage (Box 2).
Box 2.The subtle signs of lameness that are important for early detection
- Asymmetry in the movement of the dew claws with those on the affected leg not descending to the ground as much and the foot looking ‘stiffer’
- Asymmetry in stride duration, i.e. one leg swinging through faster than the other is an indication that pressure on the ‘slow’ leg is causing discomfort
- Shorter strides or a ‘choppy’ gait
The first signs that a CHL is developing are often a shortened stride or asymmetry in the movement of the dew claws, and it is cows with these signs that need to be identified and classified as lame. Waiting for an obvious limp to develop means the window of opportunity is missed and the chronicity cycle continues. If cows are identified at an early stage, then it is expected that the signs of a deep sole bruise or bruising of the white line will be seen on in-spection (Figure 4). However, if it is apparent that lesions are being identified at a more advanced stage, then the threshold between a score 1 and score 2 needs to be recalibrated otherwise the benefit of EDPET is reduced. This would involve increasing the sensitivity of the lameness detection method to more appropriately isolate early CHLs (i.e. haemorrhage stage lesions). The focus must be on achieving the best outcome for the cow and therefore, while it is tempting to give the cow the benefit of the doubt, this could impact significantly on her future lameness patterns.
Following identification as a new lameness case, cows must be treated promptly, i.e. within 48 hours of detection. Therefore, to ensure maximum benefit, there must be co-ordination between the mobility scoring and trim programme, whether this refers to communication or in-house facilities and skills is relevant to the specific unit in question.
As discussed previously, the current best practice recommendation is that any new case of lameness with a CHL is treated with a therapeutic trim, block and course of NSAIDs. If the regimen is followed correctly it can be expected that 85% of cows with CHLs will recover within 5–6 weeks (Thomas et al, 2015). However, it is important to ensure that lesions are both identified correctly and also treated correctly by someone who is both trained and skilled.
The use of hoof testers is crucial when inspecting a newly lame animal (Figure 5). They should be applied to all cases where a visible lesion causing lameness has not been identified. If identifying cows just at the start of the development of bruising, it is possible that there will be no visible lesion but a pain response will be elicited on application of the hoof testers. Incorporating a deep, wide model into the lateral hind claw before the application of hoof testers can increase their sensitivity and reduce the risk of cows that do require treatment being incorrectly considered as a false positive. This in turn can lead to reduced confidence of the scorer in their ability to identify cases accurately and in turn result in cows being flagged up at a later, more obvious stage of lameness. Consequently, this then reduces the effectiveness of EDPET, which can then lead the producer to become disillusioned with the process. This highlights the need for each person involved in each individual component to be skilled and trained, but most importantly to not see their role in isolation but as part of all those who are important in the implementation of EDPET on farm.
EDEPT in digital dermatitis control
While the benefit of mobility scoring is predominantly through the early detection of lameness as a result of CHLs, it is a less reliable method of detecting infectious causes of lameness, specifically digital dermatitis. This is because of the long lag phase between infection and clinical signs of lameness, which has been reported to be an average of 133 days (Krull et al, 2016). If using mobility scoring as the only method of detection for digital dermatitis, this creates a missed window of opportunity for treatment and increases the potential for the infection to spread. The reproduction ratio (R0) of digital dermatitis is 2.36 (Biemans et al, 2018), emphasising the importance of early detection and resolution of infection through effective treatment.
The most practical way to identify digital dermatitis lesions is to visually inspect feet in the milking parlour after cleaning the feet (Figure 6). For robotic herds this can be carried out at the feed barrier, although this is associated with a lower sensitivity (Cramer et al, 2018). As with CHLs, both early detection and effective treatment is important in control (Döpfer et al, 2012) because of the ability for the treponeme bacteria to invade and encyst in the dermis creating a ‘carrier’ state (Berry et al, 2010). Active lesions should be treated with a licenced topical antimicrobial following cleaning and drying of the lesion (Bell and Vanhoudt, 2020), with administration of a NSAID also thought to be of benefit in cases in early lactation (Oikonomou, personal communication). Where the prevalence of active lesions is high, a ‘blitz’ treatment approach is proposed with the simultaneous treatment of all active lesions to ensure rapid reduction of infection pressure (Pedersen, 2019).
Conclusion
Lameness continues to be a challenge in many of the UK's dairy herds yet, despite the evidence-based approach and documented success of EDPET, its uptake remains poor. Mobility scoring for the early detection of new cases of lameness is a crucial part of EDPET with supplementary screening for infectious causes of lameness, specifically digital dermatitis. A shift in focus needs to take place towards the detection of subtle cases of lameness. Success of the protocol is dependent on each element being conducted accurately and promptly with communication between all parties involved being key to ensure a positive welfare outcome.
KEY POINTS
- Lameness remains a significant welfare challenge to the dairy industry.
- Early detection and prompt effective treatment (EDPET) of new cases of lameness is an important component of lameness reduction programmes.
- The effectiveness of EDPET is dependent on each individual element being implemented correctly.
- Early detection of new cases is the first element of EDPET but must be undertaken with a focus on the subtle rather than obvious signs if cows are to be identified at the correct stage.
- Following identification, new cases of lameness must be inspected within 48 hours.
- The current best practice protocol for new claw horn lesions (CHLs) is a therapeutic trim, application of a block and a 3-day course of a non-steroidal anti-inflammatory drug (NSAID).
- The best practice protocol for the treatment of digital dermatitis is to lift the foot in the crush, clean and dry the lesion before applying a licensed, topical antimicrobial (repeat treatments may be required).