Bovine Digital Dermatitis (BDD) - also known as hairy heel warts, digital warts or strawberry foot rot - is a contagious disease causing painful inflammation of the skin above the heel bulbs, leading to lameness.
Rear feet are affected in 90% of cases and new cows tend to get infected 2-8 weeks after entering the herd, resulting in an often higher prevalence among heifers. After infection, cattle do develop some immunity to the disease.
While BDD cases within NZ dairy herds are low and often stay low (as we don’t intensively house cows), they can start to increase each year. Ongoing monitoring is, therefore, recommended, specifically between November and February, when prevalence peaks. To monitor your cows for BDD, their rear feet need to be hosed down and assessed during milking.
Risk factors
Risk factors for BDD are a constantly wet, muddy environment and intensive housing. It is spread cow to cow, through short term survival of Treponoma bacteria in the slurry that cows are walking through. It is almost impossible to eradicate, but individual cows can be treated and outbreaks can be prevented with regular foot baths.
Treatment options
Early lesions can be treated with daily blue spray for several days. This needs to be applied to dry, clean feet. If the lesion is small and not too invasive, the spray should be sufficient, however, if it has invaded under the wall, the underrun horn will need to be removed and follow up antibiotics will be required.
Foot baths have variable results. Oxytetracycline foot baths are most effective, but there are concerns around residues in milk and this would be costly. Copper sulphate, zinc sulphate and 4% formalin are all options. The feet must be clean for the foot bath to be effective. The rule for ensuring an adequate active solution is 100 cows per 100 litres of foot bath.
Please get in touch with your KeyVet if you would like to discuss BDD further, or to start monitoring your herd for the disease.
