Detection and Diagnosis of Lameness in Cattle

Although many factors can affect a cow’s normal gait, typical lameness detection methods are based on subjective visual identification of deviations from normal movement, as a result of pain in one or more limbs. This conventional method may lack sensitivity in detection of mild to moderate lameness. The development of automated systems of lameness detection holds promise to improve the accuracy of mild lesion identification. Whether lameness is detected through visual observation or with an automated system, follow-up diagnosis and treatment of the causative injury or lesion are essential.

A cow’s normal locomotion—also known as gait or mobility—has a stride that consists of a swing phase and a stance phase. The stance phase starts when the heel of the lateral hoof comes in contact with the ground, absorbing the initial force of impact. As the stance phase progresses, the medial hoof and internal structures, such as the suspensory apparatus and the digital cushion, distribute the impact of landing. The stance phase ends and the swing phase begins when the foot is lifted from the ground and there is no weight bearing. Differences in normal locomotion among cows can be explained by individual factors such as breed, cow size, age, parity, gestational stage, and conformation of the foot, leg, and udder. Locomotion can also be influenced by environmental factors such as the type of walking surface, moisture, traction, and/or obstacles (eg, steps, turns, unevenness).

A lame cow will adjust and/or modify her gait and posture differently depending on the origin of the pain in the foot or the upper limb, and also depending on the specific focus of pain within the hoof in cases of foot lameness. Clinical signs of lameness include changes in locomotion (eg, decreased speed, decreased stride, length and tracking, increased abduction, increased asymmetry), posture (eg, arched-back, cow-hocked, hind-limb protraction or retraction, cross-legged, knuckling of the fetlock), weight distribution (eg, weight shifting between limbs, uneven weight bearing) and changes in behavior (eg, lying, standing, feeding, socializing, ruminating).

Lameness detection is typically based on visual observation of the cow’s locomotion. Ideally, cows should be assessed where they can walk with consistent flow for at least four complete strides on a walking surface free of obstacles, turns, slopes, and steps. Numerous locomotion scoring systems have been developed to identify deviations from normal gait or posture, which are aimed at assessing beef and dairy cattle when walking and standing, as well as when being restrained (ie, stall assessment for tie-stall dairy herds). There are > 28 locomotion scoring systems worldwide for beef and dairy cattle, differing in rating scale (each 2–9 points, with the 3- and 5-point scales used most commonly), number and type of lameness indicators used (back arch, head bob, tracking up, asymmetric steps, weight bearing, stride length, speed, leg abduction and/or adduction, joint stiffness/flexion), and lameness classification (ranging from nonlame to mild, moderate, lame, or severe). In the dairy industry, locomotion scoring has become an industry standard and herd health screening practice to identify, monitor, and control lameness at cow and herd levels. Locomotion scoring is a key component of lameness prevention programs and welfare quality assurance programs.

Several factors contribute to challenges that the industry currently faces in detecting lameness and diagnosing hoof lesions. For example, pain is often masked by the cow’s stoic nature, helping to explain the low diagnostic test performance of locomotion scoring as a tool to identify cows with painful hoof lesions. There is also a lag between the time when a cow first experiences pain inside the hoof and the time when a lesion becomes visible on the sole. In addition to these factors, locomotion scoring is a subjective method that requires ongoing training, making it difficult to identify mildly or moderately lame cows. The tendency to miss mild and moderate cases contributes to the common underestimation of lameness by producers. For example, studies in North America, Europe, and New Zealand report that producers fail to detect 60%–80% of cows scored as lame by a trained outside observer. At the herd level, lameness detection and associated foot evaluation and treatment should be undertaken routinely (every 2–4 weeks). Consistently practicing lameness detection techniques on the farm, and receiving training in those techniques, can decrease the impact of lameness by improving early detection. However, these are time-consuming and labor-intensive diagnostic methods that, along with increasing herd sizes, appear to represent practical challenges to producers.

Challenges related to visual methods of detection are contributing to the development of automated technologies. Automated lameness detection systems are an area of rapid development and typically rely on either 1) kinematic methods (analyzing body motion over time, such as image-processing techniques and the use of accelerometers); 2) kinetic methods (analyzing the force applied to the body, such as from force and pressure plates and weighing platforms); and/or 3) indirect methods (ie, infrared thermography). In addition, these automated detection systems typically use algorithms designed to process the data and filter out noise. The extent of development and accuracy of these technologies for use in lameness detection, as well as their efficacy in decreasing the impact of lameness, can vary widely. Considering the potential for these automated systems to be cost-effective on farms, along with their added animal welfare benefits, commercially available automated early warning systems are likely to become more commonplace on dairy farms.

It is important to bear in mind that lameness is a clinical sign and not a disease in and of itself. Therefore, the cause of lameness at cow level should be located and determined using the steps below. The history and environment of the animal should be considered when interpreting findings from a general clinical evaluation and a more detailed physical evaluation.

Steps in a lameness exam:

1. Locomotion evaluation: The purpose of evaluating locomotion is to obtain an initial impression of the anatomical location of pain and subsequent lameness, and to evaluate recovery after treatment. Evaluating locomotion involves assessing the cow’s posture (eg, back, shoulders, pelvis), movements (eg, while rising and lying down, when possible), and each limb and digit. Typically, gait evaluation can determine whether lameness is in the front or hind limb and, sometimes, whether it is in the upper limb. In most cases, especially for dairy cattle, a detailed foot exam should always be performed first, before considering the upper limb as the origin of lameness. (link to Visual Locomotion Scoring videos)

2. Physical limb examination: Once the affected limb has been identified, the cow should be properly restrained, and each limb and foot properly secured for a more detailed evaluation. Unless there is an obvious visible lesion, the foot should be thoroughly inspected for swelling, lesions, and foreign objects, including the interdigital space and heel bulbs. In most cases, this inspection will require a functional hoof trim as described under Components of a Hoof-Trimming Program. If no obvious lesion is visible during or after hoof trimming, hoof testers should be used to evaluate pain reaction in the hooves. Proper use of hoof testers means applying appreciable pressure (while being careful not to squeeze the coronary band) and observing the cow’s response (eg, kicking, withdrawing, muscle tightening, or flinching). If the problem originates in the foot, functional hoof trimming can be followed by therapeutic trimming. If no foot lesion is identified or no pain response to hoof testers is elicited, careful palpation of joints, muscles, tendons, and bones, as well as manipulation of the limb (flexion, extension, abduction, and adduction) will be required to determine the cause of upper-limb lameness.

3. Other diagnostic tools: For lameness that is not easily identified, or when additional data are required to determine the prognosis or the most appropriate treatment, the use of ancillary diagnostics is warranted. Digital nerve blocks or intravenous regional anesthesia (2% lidocaine, 20–30 mL), administered distal to a tourniquet above the dewclaw, can be used to help differentiate foot lameness from upper-leg lameness. The same approach can be used for painful therapeutic procedures, including the removal of sensitive tissue and affected bone. Tourniquets can be left on for up to 60 minutes without complications and anesthesia will persist after tourniquet removal. Lameness can be evaluated after tourniquet removal. More complicated diagnostic procedures, including imaging, arthroscopy, arthrocentesis, and synovial fluid analyses, are typically reserved for animals of higher value and typically carried out in a hospital setting. Arthrocentesis with subsequent synovial fluid analyses can be used if joint disease is suspected (ie, septic arthritis, osteochondrosis, trauma). Radiographic imaging can help in diagnosing fractures, luxations, septic arthritis, and osteochondrosis. Ultrasonography can be used to examine soft tissues of the musculoskeletal system, and to aid in the diagnosis of septic arthritis, tendonitis, osteochondral fragments, and muscle injuries.

4. Differential diagnosis and treatment plan: The lameness exam findings typically make it possible to develop a list of differential diagnoses and a working diagnosis, along with a treatment plan. A wide variety of differential diagnoses exist for lameness and are described under Lameness Originating in the Hoof.