Footrot continues to be a concern for sheep producers across the province.
The virus’s ability to survive in warm and wet conditions, and on the hoof of previously infected sheep for many years, makes it a difficult disease to control.
“Mud and manure (help) to cause abrasions to the skin to help the infection get started. (Then) bacteria living in this environment from sheep that have been previously infected dropping that bacteria, other sheep are now going to pick it up out of the manure in our conditions,” says Dr. Rex Crawford, owner of Dufferin Veterinary Services during the 2021 Grey Bruce Farmers’ Week Virtual Conference and Trade Show Sheep Day.
Why it matters: Footrot is a concern for sheep producers as it leads to overall decreased production due to the animals being lame and reluctant to eat.
When cases of footrot or foot scald are thought to be present it’s ideal to do some foot trimming to allow for better examination of the hoof, but not to aggressively trim close to the infected tissue.
For individual and mild cases, a topical treatment is ideal.
“My preferred treatment is a Cyclospray, which is an oxytetracycline antibiotic spray — it’s nice and easy to apply. We might also sometimes use Koppercare or Kopertox as our topical antiseptic treatments.”
Individual cases of severe footrot and foot scald with swelling in between toes and a white layer of puss, should also be treated with injectable antibiotics.
“Long-acting oxytetracyclines is what we are going to use. These are (administered at) 4.5 mL per 100 lbs., into the muscle. It’s important to speak with your vet about withdrawal times if (using) one of the oxytetracyclines that doesn’t have ‘sheep’ specifically on the label.”
As well, it is suggested to consider a painkiller for severe cases or animals that are still lame three days following initial treatment.
Controlling an outbreak
When numerous animals are infected in the flock producers need to become proactive and look at strategies to control the infection rather than treat each animal.
“At the point that we have some infected animals in the flock – depending on how big our flock is, how badly it has snowballed out of control on our farm in previous years — that will determine if we need to put a control strategy in place.”
Footbathing with a zinc sulphate solution is the number one method used by producers at a rate of one to two kilograms per 10 litres of water.
The solution needs to be five to six centimetres high to cover the entire hoof. It is advised that sheep have a minimum 15-minute soak, up to one hour.
“If we are in the middle of a major outbreak, we probably want to go with that one-hour soak.”
Ideally, a dry spot will be available following the footbath, such as concrete, for 20 to 30 minutes so the sheep hooves can completely dry.
Eliminating virulent footrot may be better than dealing with it annually, says Crawford.
“Eradication strategies are something to consider if footrot is an annual problem on your farm, particularly if it’s an annual problem that is getting worse year after year. It takes a tremendous amount of effort to eradicate footrot from a farm so it is something that we want to think about before that effort is put in.”
The eradication strategies are best after the major transmission period such as mid-summer, if dry enough, or in late fall after it is too cold for the bacteria to spread.
Eradication strategies include inspecting all sheep for signs of footrot. Infected animals should be removed from the main group, culled immediately, or treated with long-acting antibiotics or aggressive footbaths.
“We want to re-inspect all the sheep four weeks later, particularly important for the sheep that we (isolated) after our first inspection. We want to make sure that they haven’t been reinfected.”
Infected and treated sheep should be culled if not cured.
If managed properly, footrot can be better controlled.