Nick Bell MA VetMB PhD Pgcert Vet Ed FHEA ECAWBM (AWSEL) MRCVS
Reviewed byNick Bell MA VetMB PhD Pgcert Vet Ed FHEA ECAWBM (AWSEL) MRCVS 2016
Bovine digital dermatitis is an
infectious condition of the foot caused by bacteria called
Treponemes. Infections typically result in ulcers and/or warts just
about the heels (Figure 1). It was first reported in Italy in 1974.
Since its appearance in the UK in 1987 it has spread widely and is
thought to affect the majority UK dairy herds and many beef
Lesions can have a highly variable
appearance (Figure 2a-e below) and can be found at a range of
sites. The classic site is on the skin around the heel (Figure 1)
but Treponemes are implicated in lesions under the heel horn, on
the coronary band, on the skin between the claws, under the dew
claws, on the pastern skin on ulcerated hocks , on teat lesions and
on the udder skin (Figures 3a-c).
Within infected herds approximately 41% (0-67%) of cattle
typically have heel lesions although only a small proportion, if
any, will be ulcerated as in Figure 1.
Fig 1: Digital dermatitis at the classic site above
the heel bulbs.
Fig 2a: An erosive lesion, with watery discharge.
These are often very painful and frequently bleed on
Fig 2b: The strawberry-like granulomatous lesion,
often covered with a grey layer of dead tissue.
Fig 2c: The dark, crusty appearance of a healing
lesion which is not painful.
Fig 2d: The fronds of a 'hairy wart' which are
Fig 2e: Mixed lesions which can contain any
combination of lesion types above.
Cost of disease
The estimated costs associated with digital dermatitis are
probably inaccurate and an under-estimation of the true cost. Many
cases of complicated interdigital growths and severe lesions like
necrotic toe and wall lesions, severe heel erosion, severe sole
ulcers, severe cases of foul-in-the-foot, teat necrosis and udder
sores are usually associated with digital dermatitis and are not
included in the calculations. Estimated cost per case vary from £75
to £81.49, making the annual cost per average farm roughly £3000
per 100 cows. Like sole ulcers, much of the cost is related to milk
yield loss and increased calving interval (Table 1 below)
Table 1: Production and
welfare statistics regarding digital dermatitis
Measure of production and welfare
Impact of digital dermatitis compared with
Reduced milk yield
Various estimates of milk yield loss:
- 0-57 litres
- 1.7% reduction
Infertility - Calving to 1st service
*Impact comparisons are generally made between cows
individually treated for digital dermatitis and those that haven't
received treatment. Many infected cows will fall within the
untreated group as most are treated in the footbath or eventually
recover without treatment. Therefore, these costs are likely to be
Fig 3a: Coronary band
Fig 3b: Infected interdigital
If digital dermatitis is affecting front feet, then this can
cause more severe lameness and would indicate exposure to deep
slurry somewhere on the farm.
Fig 3c: Toe necrosis
invoice Treponemes, the bacteria casuing digital
Biosecurity - preventing new strains of digital
dermatitis entering a herd
The main source of infection are other animals with lesions and
once a herd is infected, digital dermatitis appears to be
impossible to eradicate (but can be very effectively treated and
prevent at individual animal level). There are many species of
Treponemes causing digital dermatitis, some of which produce
more severe disease. This means even herds with digital dermatitis
are likely to benefit from strict biosecurity precautions.
Therefore, all herds should consider having:
- Closed herd status, including hire bulls, or buying from herds
certified free from infection by a vet or a protocol to prevent new
straing entering the herd.
- Boot and equipment disinfection facilities for visitors before
they enter cow yards (Figure 4).
- Dedicated claw trimming equipment that has never been used on
Individual cow treatment - reducing the reservoir of
Cows affected with digital dermatitis are usually easily spotted
by the way they behave: they appear to walk on their toes and they
shake their feet while stood. The lesions can also be spotted by
walking through groups (pen walks) or hosing off the heels in the
parlour and using a bright light to identify abnormal heel skin.
While it is quick and simple treating cases by spraying treatment
in the parlour, it is probably more effective to first clean and
then treat the foot in a crush.
Trimming using the Dutch 5 step method
(see previous module) is essential to rule out claw lesions before
assuming digital dermatitis is the only problem causing lameness.
Trimming away eroded heel horn may reveal digital dermatitis under
the heel and may increase the exposure of the lesion to
Fig 4: Provide disinfection
The majority of digital dermatitis lesions respond very well to
a combination of:
- Simple cleaning (running water or a brush in disinfectant
especially the pocket of skin between the heels.
- Hygienic drying (e.g. disposable blue towel)
- A generous application of a licensed antibacterial product e.g.
copper gel or salicylic acid. If antibiotics are used they
should be applied generously and allowed to dry with at least
applications at the start and then repeated daily until resolved.
While bandaging with antibiotic powders has proven extremely
successful, this is an off-license treatment and milk residues are
reported. Bandages do not appear to improve cure rates and pose a
constriction risk if the foot swells or if the bandage is left on
for more than a dew days.
- Return to a clean, dry yard following treatment, avoiding
exposure to slurry and mud that could interfere with the newly
- Repeat the treatment daily until resolved and generally for at
least 3 days
The wart-like lesions are more difficult to treat and are likely
to recur. Recent research suggests products containing salicylic
acid may be most effective even with warty lesions. While hygienic
trimming back with a sharp knife prior to spraying may work, it is
important to avoid cutting into the sensitive (and bleeding)
tissues. This is difficult and knives become contaminated.
Severe and very painful cases may benefit from surgical removel
under local anaesthesia by a veterinary surgeon. The animals with
warty lesions need consideration as they readily re-ulcerate and
contribute to the majority of the infectivity for the rest of the
Controlling digital dermatitis at the herd
One visible infection will represent the tip of the iceberg with
many other cows bearing lesions which are more difficult to see. As
mentioned, the warty lesions represent an important reservoir of
infection for the rest of the herd. There are several ways to treat
a herd if treating all infected animals ina crush is not feasible.
One option is to walk the walk the whole herd (including dry cows
and groups of youngstock that appear infected) through a footbath
containing antibiotic, antibiotic but this is off-license and is
not an ethically defensible use of antibiotics. Alternative
approaches involve the use of copper, zinc or an organic acid
preparations at the appropriate concentrations or a rising
concentration of formalin (see later module on foot bathing). Feet
must be clean for herd treatments to work.
In most instances the digital dermatitis will return within a
few weeks if the spread of new infections and re-development of old
lesions is not prevented. Regular (daily) foot disinfection
(see later module), hygiene at foot trimming and steps to improve
yard or pen hygiene are most effective for this. To monitor this,
assess the number of cows with lesions by hosing feet in the
parlour and assess general cow foot cleanliness.
Some animals and families appear more predisposed to infection,
either through conformation or some other genetic trait. Cow and
herd immunity is important, and should be reviewed when
outbreaks are encountered. BVD infections have been associated with
outbreaks. Similarly, if large numbers of fresh heifers join the
herd, then outbreaks are more likely.
Digital dermatitis is a relatively simple infectious disease to
control given attention to treating the animals that are the
reservoir of infection and reducing the spread of infection. This
can be summarised as:
- Treating the reservoir
- Individual animal treatment
- Herd treatment - footbaths (see later module)
- Reducing the spread and re-development
- Treatment hygiene - using disinfectant to wash hands, equipment
and the foot at routine claw trimming or lame cow treatment
- Foot hygiene - better scraping, removing sources of deep
slurry, water or mud. Feet are naturally cleaner with deep straw
beds or at pasture.
- Foot disinfection e.g. daily 4% formalin foot baths.
While treatment will undoubtedly help control the disease,
preventing spread will result in less production loss and will be
more cost effective. Biosecurity is essential for preventing
more severe forms of the disease entering the herd.