When lame cows are noticed it is imperative that they have their feet picked up and checked so that the cause of the lameness can be remedied. It is important to understand the roles of the basic structures of the cow's foot so diagnosis can be made. Once cleaned it is best to scrape or sand the surface of the foot so any small cracks, bruises, white line disease or ulcers can found.
The accompanying photo is of the bottom of a non-lame normal foot that has been trimmed.
Often the first step, once the foot is safely roped up, is to remove the excess dirt and mud so the structures outlined in the photo can be checked. The important structures of the foot include:
1. The wall: this is the hard protein outside layer of the foot. It is the main weight-bearing part of the foot. This protein can soften with moisture, making damage and penetration easier. In dry summers, it can become hard, which can lead to cracks.
2. The sole: this is the layer that covers most of the base of the claw. Little weight is borne on the sole and it is a softer material. Think of this as a base designed to keep mud out of the inner layers of the foot, but not designed to be bearing weight.
In the normal cow, it will be about 0.5 centimetres thick. If it becomes too thick and the cow is bearing weight on it then we can see bruising and pressure ulcers. This can also occur in normal thickness soles if the outer wall is too short and causes weight bearing on the softer sole. If this is penetrated infection can track inside the hoof to form an abscess. If it is partially penetrated especially with thin cracks, then dirt can force its way in.
3. The heel or bulbs of the foot. These are seen from behind the cow most easily. The outer layer of the bulb is thick skin that gets thicker and denser as it nears the part of the bulb that contacts the ground. These act more like shock absorbers.
4. The White Line. This is the grey to white line visible where the sole joins the hard wall. This is the junction of the sensitive tissue with the non-sensitive tissue and is a weak point of the foot. It is prone to having dirt penetrating it in small little 'holes' or cracks. As the cow walks the dirt is trapped by the wall and pushed further up into the white line. This is a common cause of foot abscesses.
Any dark 'dots' in this layer will usually be pared away and carefully followed, pus is often released from these. If these go untreated, the dirt and infection tend to be pushed all the way up the inside of the wall until it breaks out at the coronary band.
5. The coronary band. This is where the top of the hard wall joins the normal skin of the leg. It is also where the growth for the wall originates from (just as your nails grow from the nail bed so does the cows hoof wall).
6. The interdigital space. Don't forget to check the space between the claws, it is common to pull gravel or even sticks out of this area. Footrot will make this area swollen and moist with a slimy exudate. When footrot is present there is usually a crack in this interdigital space or at the back between the heels.
Don't forget that when unsure about what is causing the cow to be lame after checking the foot or if uncertain about how to treat it, then call a veterinarian for advice.
Until next time, good milking.<\#9>D
*Sherri Jaques is a practising veterinarian and reproduction adviser in the West Gippsland region of Victoria. All comments and information discussed in this article are intended to be of a general nature only. Please consult a veterinarian for herd health advice, protocols and/or treatments that are tailored to a herd's particular needs.
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