Researchers Review Treatment and Outcome of Canker in Horses

Researchers Review Treatment and Outcome of Canker in Horses

Overall, 75% of owners considered the outcome of treatment and recovery to be "good" (no recurrence) or "acceptable" (recurrence, but manageable with minor treatment).

Photo: Maarten Oosterlinck, DVM, PhD

Most horse owners are familiar with the foul-smelling problem that frequents many horses' feet: thrush. While it can be a challenge to treat, thrush often clears up with few lasting effects. However, another foul-smelling hoof ailment--canker--can cause more lasting problems than thrush and can even be fatal if severe enough. A team of Belgian researchers recently completed a retrospective study on the diagnosis, treatment, and outcome for horses suffering from canker in order to further veterinarians' knowledge of this rare hoof condition.

"Equine proliferative pododermatitis, or canker, is a debilitating disease of the hoof characterized by chronic hypertrophy (enlargement) of horn-producing tissues, mainly in the frog region," explained Maarten Oosterlinck, DVM, PhD, a post-doctoral research associate at Ghent University. "As opposed to thrush, which causes destruction of horn tissue in the sulci (the grooves on either side) of the frog, canker is a proliferative disease affecting the horn of the frog anywhere throughout its structure."

A condition that produces "foul-smelling, cheese masses" with cauliflowerlike growths, canker has been noted most commonly over the years in draft horses, Oosterlinck relayed, but any breed can be affected. Canker is found in both the front and hind limbs, although previous research indicated it has a slightly higher prevalence in the hind limbs.

"The cause remains obscure," Oosterlinck explained. "Infectious agents such as bacteria, viruses, fungi, and spirochetes have all been suggested, but environmental conditions (such as wet or unsanitary conditions) have also been blamed as stimulating factors."

Surgical debridement (removal of diseased and dead tissue), medical treatment, and therapeutic hoof care have all been used successfully as treatments for canker, but no one treatment has been noted in being consistently effective, he noted.

In the present study the team reviewed the medical records of 30 horses (mares, stallions, and geldings of varying breeds and ages) admitted to the Ghent University Faculty of Veterinary Medicine from Oct. 2001 to April 2009 to determine the long-term outcome of their treatment protocol for horses with diagnosed canker. The team also examined the effect of adding oral prednisolone--a steroidal anti-inflammatory agent--to the recovery process.

Key findings about canker diagnosis in their review included:

  • Forty-four hind limbs and 41 forelimbs on 30 horses were affected by canker, and more than 70% of horses were affected on two or more feet;
  • An initial diagnosis of canker was made by the referring veterinarian, farrier, or owner in only five cases, and a presumptive diagnosis of thrush was made in 19 cases; and
  • Seven horses were treated for thrush for several years before being admitted to the hospital and attaining a correct diagnosis.

Key findings about the treatments used on the horses included:

  • All horses were treated with surgical debridement;
  • Thirteen horses were treated under general anesthesia, 13 were treated under local anesthesia, three were euthanized upon diagnosis, and one was taken home and did not receive treatment from the hospital;
  • Seven horses received prednisolone with treatment; those horses had significantly shorter hospital stays than those not administered prednisolone.

Finally, the team's long-term follow-up information (which was collected on 24 of 30 horses) indicated:

  • No recurrence of canker was reported in 10 of 24 horses, while the rest of the horses experienced some degree of recurrence;
  • Horses that received treatment before being referred to a hospital had a 13-fold higher chance of developing a recurrence;
  • Eight of the 14 horses with recurrence were managed successfully with regular veterinary and farriery attention;
  • The remaining six horses were euthanized after they failed to respond to treatment; and 
  • Overall, 75% of owners considered the outcome of treatment and recovery to be "good" (no recurrence) or "acceptable" (recurrence, but manageable with minor treatment).

"The present study confirms that the prognosis for severely affected horses is at least guarded, with 75% of horses showing acceptable long-term outcome," Oosterlinck noted. "Besides adequate debridement and dedicated hoof care, additional oral treatment with prednisolone significantly shortened the duration of hospitalization and therefore can be considered as a part of a treatment rationale for canker."

Additionally, the study results suggest that an accurate diagnosis and quick treatment seem to yield the most positive results. Having an experienced farrier and/or veterinarian examine horses suspected of having canker is advisable. Moreover, teamwork between farrier and veterinarian and owner-compliance to therapy and daily hoof care are essential, Oosterlinck concluded.

The study, "Retrospective study on 30 horses with chronic proliferative pododermatitis (canker)," was published in the September 2011 issue of Equine Veterinary Education. The abstract is available online.

About the Author

Erica Larson, News Editor

Erica Larson, News Editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in three-day eventing with her OTTB, Dorado, and enjoys photography in her spare time.

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