Livestock An M4 lesion.
Treatment options Identifying affected cows can be a challenge. Examination of the area between the claws is important to improve this process. Most DD lesions are seen on the hind feet, so examination can be performed in the parlour with the aid of a bright light and a mirror to examine the interdigital space (spreading pliers can be useful). When treating individual animals, it is important to follow a standard process to ensure all lesions are treated correctly: • Lift and trim as necessary • Clean the identified lesion(s) removing any scabs and surface discharge • Dry the area and apply topical treatment as advised by your vet.
Managing and treating digital dermatitis Most UK dairy herds are now considered to be affected by DD. Veterinary surgeon and ruminant veterinary advisor at Ceva Animal Health, Kythe Mackenzie, offers a guide to effective scoring, control and treatment. DD infection usually results in ulcerated and/ or wart-type lesions around the heel bulbs and between the claws, but lesions can also be seen on the hock and udder skin. Lesions can be classified using the M score scoring system (see table). On an individual animal, several lesions at different stages of the disease may be found at any one time. It takes in the region of four months for an active lesion to be seen following infection of healthy skin. However, in the persistence of disease in the herd the reactivation of chronic (M4) lesions is more important and can occur within two weeks.
Impact and cost As one of the most common causes of lameness and with a prolonged duration, DD can significantly impact welfare and production. In one study, heifers that had one or more DD lesion in the six months pre-calving had 24 more days open and a reduction in milk yield of 335kg in their first lactation compared to heifers that had no lesions. In another study, DD had a negative impact on welfare and a reduction of up to 5.5kg per day in milk yield for up to six weeks. AHDB recently assessed the cost of lameness at £2.20 a day and the cost of a case of DD is estimated to be in the region of £100.
Control is key Biosecurity is vital – infected animals are the primary source of infection and the bacteria can be spread by animals or equipment. Slurry impacts skin quality, allowing the infection to be established and may lead to bacterial transmission. External biosecurity keeps the disease or new strains of the bacteria out of the herd. New animals should be isolated and have their feet inspected. Any lesions identified should be treated and all animals footbathed regularly during the quarantine period to reduce the risk of disease incursion. Internal biosecurity aims to minimise infection pressures – excellent hygiene and slurry management are important, alongside disinfection of hoof knives between animals with a contact time of at least 20 seconds. The whole herd, including dry cows and heifers, must be considered when putting control plans in place. To prevent infection entering heifer groups, separate equipment and boot dips should be used by staff. Footbathing is a mainstay of both control and treatment for DD (and other foot lesions). The foot bath should permit good cow flow, have an appropriate depth and frequency of contact using the correct concentration of biocide (your vet will recommend the most appropriate agent for your farm).
A recent study supports the use of a zero milk withhold NSAID for pain relief and antiinflammatory activity in cows with active DD lesions. During the study, all cows with an active DD lesion were treated as per the protocol above, then one group had a single injection of a zero milk withhold anti-inflammatory drug whilst the control animals did not. The results showed that lame animals at the time of diagnosis were 20 times less likely to be lame a week later if treated with the NSAID. There was also a benefit in milk yield – on average, treated animals gave nearly 3kg more but the freshly calved cows, which were lame at diagnosis, gave over 10kg more. Whole herd (‘blitz’) treatment can be used to reduce the number of active lesions and bacterial load; this is important when we consider how long it can take for a newly infected cow to develop a visible lesion. For a blitz treatment, all cows (milking and dry) are examined and treated before management changes are implemented to maintain the reduction in infection pressure that treatment has established. DD management should aim to reduce the exposure to the causal bacteria and treatment needs to be prompt and effective. The use of a NSAID can improve cattle welfare as well as production outcomes. FG
Table: M score scoring system Active lesions
Inactive lesions
M1: < 2cm focal lesion
0: No lesions – check between claws
M2: >2cm ulcerated or granulated lesion
M3: Healing stage
M4.1: Chronic stage with small active area
M4: Chronic stage often a hairy wart
An M2 lesion active and painful ulceration (>2cm).
May 2022 www.farmersguide.co.uk 83
16:08
78-91 Livestock.indd 83
19/04/2022 09:16
