Many of the issues that lead to lameness in dairy cows begin with heifers either before calving or in the first lactation, Gloucester vet Roger Blowey said at a recent meeting in Cookstown.

At the event organised by Provita, Blowey explained that the corium in the inside of the hoof acts as support tissue which carries blood and is needed for formation of the horn (outer surface of the hoof), as well as bones in the foot.

Damage and inflammation of the corium can therefore lead to bone deformities. “Small changes will eventually build up until the cow is chronically lame. For cows with bone deformities there is not much you can do. It is a patch-up job at best,” Blowey said.

The effect of corium damage on the horn is similar to humans getting a black nail. The difference is that the horn grows at 5mm per month so it will be one or two months before the initial damage is seen at the surface of the hoof, which then leads to ulcers.

Disorders at the white line (where the hoof sole and wall meet) are also brought about by inflammation associated with the corium.

At the heel of the foot is the digital cushion, a fat pad that surrounds the corium to absorb shocks as the cow walks. Blowey said that thin cows will have a thinner digital cushion compared to better conditioned cows. “A lame cow can go thin but it is also likely that a thin cow will go lame,” he said.

Pre-calving

Blowey recommended that heifers should have access to concrete before calving and pointed to research, which showed that calves that walked on a concrete lane each day had thicker digital cushions.“Heifers naturally have poorer quality fat in the digital cushion until the second or third lactation so heifers that get pushed back at feeding and have prolonged standing times have more risk of bruising,” he said.

Blowey advised that heifers should ideally be reared in cubicles, mixed with dry cows pre-calving and run through the parlour and footbath daily. After calving, heifers should be in a separate group with adequate feed space and milking order that allow short standing times, and be footbathed twice daily.

He said that early intervention with lameness was crucial and quoted an experiment that found cure rates dropped by 15% if treatment of lameness was delayed by two weeks.

Another study showed that the length of pedal bones in cows’ feet ranged from 52mm to 79mm, so hooves should not all be trimmed to the same length in a herd, Blowey said.

Digital dermatitis

Footbathing heifers was recommended to reduce incidences of digital dermatitis. Blowey maintained that a cow that has the infection pre-calving, is four times more likely to have it during lactation.

Although digital dermatitis causes around 25% of lameness cases in the UK, Blowey said that little is known about how it is transmitted, and more research was needed in this area.

He described digital dermatitis as “mastitis of the feet” and suggested that practices used in a parlour to limit spread of mastitis such as washing gloves and equipment after handling an infected cow could potentially stop the spread of digital dermatitis when hoof trimming.

Susceptibility to digital dermatitis has genetic links, and Blowey recommended culling problem cows if levels of the infection in the rest of the herd are under control.