22 FEBRUARY 2017
Almost all of us reading these technical bulletins will be familiar with the Dutch 5-step foot trimming method. It's been the mainstay of standardised foot trimming in cattle for over 30 years. However, during that time there have been some fairly major changes to our cattle, both in terms of the animals themselves as well as the housing and environment we keep them in. Our approach to foot trimming has had to keep pace, and there have been a few papers recently that have reported some necessary improvements for our dairy cattle trims.
The steps are summarised below for the hind foot: Steps 1 – 3 constitute the functional routine foot trim.
Step 1 – Cut back inner (medial) claw to a length of 7.5cm, measured from the coronary band where the horn starts to the toe point. Cut should be vertical to the sole and the sole horn trimmed to a depth of 0.5cm. Recent papers have shown trimming to this 7.5cm length in our large HF dairy cattle may lead to the sole being trimmed too thin and predisposing our cows to lameness. It is suggested that for our larger cows, a longer claw length of between 8.5 – 9.5cm should be used, to preserve more sole depth.
Step 2 – Cut back outer (lateral) claw to a length that approximately matches the inner claw we trimmed in step 1. Aim to reduce the sole depth at the toe to 0.5cm, but it is more important to preserve heel / bulb sole depth on this outer claw (because it carries more of the cows’ weight)
Step 3 – Modelling (“dishing”) inner aspects of both claws. Aims to unload the sole ulcer site as well as open up the space between the claws (interdigital space) to prevent build up of dirt, bedding etc. The medial (inner) claw of the hind foot has a steep and narrow model taken to open up the interdigital space. Recent papers have described taking a wider and relatively shallow “dish” on the weight bearing outer-claw to preserve sole depth whilst still unloading the sole ulcer site. By taking this dish wider it is thought more of the weight is taken through the claw walls and improves sole ulcer prevention.
Step 4 – Curative step – aims to identify any defects and trim these down further to unload the affected claw. A recent paper has suggested that the application of a block, when properly placed, significantly increases cure rates and speeds recovery and implies that when insufficient unloading can not occur because depth of sole is too thin, then the operator should not hesitate to correctly apply an appropriate block.
Step 5 – Curative step – final tidy up of claws, removing loose horn and hard ridges, particularly at the heel area. Take care only to remove fissures in the heel of the inner claw, leaving the rest of the claw untouched as excessive removal at this stage may affect stability and the height of the inner claw. If not already done so complete a thorough check for digital dermatitis and treat appropriately.
Finally, there has been a lot of press coverage in recent months concerned with Digital Dermatitis (DD). DD first appeared in the 1970s and since then has spread pretty much worldwide. A lot of work has concentrated on the cause and it seems near certain that the main “bug” responsible is a group of bacteria named treponemes.
The main clinical feature is severe lameness caused by an ulcerative wound with skin dermatitis on or just above the coronary band, usually between the heel bulbs and more than 80-90% of cases are found on the back feet. Long-standing lesions often develop wart-like fronds/growths. Recently new forms of other cattle foot lesions have been identified which have previously been thought of as non-infectious, e.g. toe necrosis, sole ulcers and white line disease. However, it is now known that these chronic cases which don’t respond to typical treatments are actively infected with the same bacteria which cause DD. These DD-associated conditions like toe necrosis or sole ulcers are particularly destructive and cause severe disease. There is also growing evidence of a genetic predisposition to DD, making the breeding of resistant or at least less susceptible animals a possibility for the future.
Recent studies have also looked extensively at the treatment of DD and risk factors for becoming infected. It has become clear that the infection stimulates a strong but ineffective immune response which doesn’t provide good immunity against re-infection. Additionally, the treponeme bugs largely responsible for the disease are found almost exclusively on the bovine foot, only rarely being detected in just two other locations – the mouth of infected cattle and the rectum. Studies of the farm environment, including slurry, have repeatedly tested negative for the these most troublesome bacteria. This strongly suggests direct contact is required between cattle to spread the bacteria – emphasising the importance of hygiene in communal areas such as cubicle sheds, passageways, milking parlours and particularly equipment that has direct contact with an infected DD wound, e.g. hoof knives, grinders, crush, ropes etc. These must be properly and thoroughly disinfected between each and every cow on infected farm premises.
A recent finding has suggested that inappropriately treated chronic DD lesions can “revert” back to an active painful and infectious wound, which identifies a very real and substantial reservoir of infection within infected herds.
Treatment studies in the field are few and far between, however lab studies and extrapolation from related diseases caused by the same bacteria in humans has proven that the most effective antibiotic against DD causing treponeme bacteria is penicillin or penicillin derivatives. Those antibiotics considered only moderately effective include lincomycin, oxytetracycline and ceftiofur (a nil-milk withhold drug). This means that a large proportion of the DD cases treated with a topical antibiotic spray and / or an injection with a nil-milk withhold product are actually being only moderately effective in treating the DD and may increase the likelihood of the DD developing into a chronic form which can later revert back to an active infectious wound in the future.