Interdigital dermatitis frequently occurs in dairy cattle and is one of the main infectious causes of lameness. The skin of the digits in the heel area and the interdigital space is affected which is characterized by a wet, smelly type of infection. This results in an aberrant formation of claw horn, leading to elevated horn ridges and V-shaped fissures in the heel area. Due to overcharging, lesions form in the claw sole at this location, which often result in sole ulcers.
2. Digital Dermatitis (Mortellaro’s disease, Italian foot rot)
Digital dermatitis is present on many dairy farms and besides being very infectious, it is very hard to get rid of. Several different types of bacteria affect the skin in the interdigital space, which is characterized by red, hairless and very painful lesions. Due to their appearance, the lesions are often referred to as “strawberry like.” Most frequently they are seen at the back of the foot, in the interdigital space between the two heels. Very specific about Italian foot rot is that the lesions may become “inactive” after which they either heal or are re-activated. Animals may keep the affected limb off the ground and/or are severe lame, due to the painfulness of the lesions.
3. Panaritium (foot rot, interdigital phlegmon)
Due to lesions or weakening of the skin at the interdigital space, bacteria may enter and infect the subcutaneous tissue. Infected animals are suddenly severely lame, and immediately above the interdigital space the foot shows a distinct swelling. This may ascend above the fetlock joint. In addition, these animals have a fever.
4. Sole ulceration
A sole ulcer forms when the corium (skin) underneath the sole horn is damaged and dies off. This leads to the absence of any horn formation at this location, and therefore a “hole” in the horny shoe. The underlying fat tissue bulges outwards through this hole, forming the specific “view” of a sole ulcer. Through the sole ulcer, bacteria can enter the underlying tissue and damage tendons and nerves when the infection ascends towards the fetlock joint.
A sole ulcer is most often seen at the outside claw of the back feet, just in front of the heel of the foot. Here most pressure is on the underlying tissue due to the attachment of the flexor tendon to the pedal bone (rotational point). As mentioned before, sole ulceration is often related to the presence of interdigital dermatitis. The aberrant and exuberant horn formation leads to overcharging of this specific area, resulting in necrosis of the underlying dermis and ulceration of the sole.
Laminitis is a disease of the corium in the foot: this becomes inflamed and blood flow within the foot is disrupted. The exact causes are not yet known although there are clear indications that nutrition, housing and feed management play a role in the development. Laminitis most often occurs during periods of stress or nutritional changes, such as in the transition period.
Due to laminitis, horn formation is abnormal and the horn itself is not as dense and strong as regular horn. This is most often only noticed later on by the horizontal rings on the shoe, a “dented” claw, yellow-reddish coloration of the sole horn, double soles and defects in the white line. This is why hoof trimming between 80 and 100 days after parturition is very interesting, because this will give you additional information on the transition period.
6. White line defects
The white line in the claw is where the horn formed by the sole attaches to the horn formed by the coronary band of the foot. Due to these two types of horn joining together, the white line is less strong than other parts of the claw. Additionally, laminitis may deteriorate the strength of the white line.
White line defects occur when foreign objects (little stones, small metal/wood pieces etc.) penetrate the white line. If they (and dirt) penetrate all the way to the corium, they cause an infection of the corium forming an abscess. This is very painful, which often causes sudden and extreme lameness. Abscesses, when not detected early on, may search for a way by pushing upwards and discharging at the coronary band.
7. Tyloma (interdigital growth)
A tyloma is a growth of tissue in the interdigital space due to chronic irritation of the skin. This irritation may be both infectious and non-infectious. Treatment exists in taking away the cause of irritation, and in extreme cases the tyloma may be surgically removed.
Source pictures: Vetvice, PTC+, Gezondheidsdienst voor Dieren