Canker is a rare hoof infection affecting surface tissues. (In a recent sampling of 150 farriers, only six claimed to have seen a case of canker.) Canker can be life threatening and should be immediately dealt with by professionals. The specific cause of canker is unknown but there does appear to be a reliable method of healing it, provided specific guidelines are observed.
Diagnosing Canker
Canker can show many different faces. For instance, over the years, six documented cases of canker each presented different symptoms based on the treatments used, as well as the time elapsed between diagnosis of the animal and treatment. Culture samples on suspect tissue have not proven as effective as biopsy samples in the diagnosis of canker.
My farrier insists that the first symptom of canker is the presence of bristly hair growth on the bulb of the heel at the cornet band level.
hair on blub
It is my belief that canker usually starts between the bulbs of the heel and infiltrates the digital cushion, which has a very poor blood supply. This tissue then takes on the appearance of cottage cheese and the condition spreads to the sub-solar tissue.
cottage cheese
At this stage canker looks like proud flesh interspersed with healthy cellular tissue. The entire frog gets undermined and infected to the extent that the frog feels detached. In the majority of the cases that I have treated, the entire frog had to be removed due to the infected tissue, but in each case, the horse’s feet returned to normal.
With all the aforementioned variables in symptoms, it is important for a suspecting owner to get the best professional farrier and veterinarian service available (not the most expensive) but the most experienced with canker. Utilize your network of professionals to ascertain who best can advise on canker infection.
How to Treat Canker
Start with the right team: a farrier with a sharp knife and veterinarian with a sharp eye. The challenge of the task produces a good working relationship because between them, they may only have worked on a total of 30 cases in a lifetime (they both would likely agree this was enough). The work involves trimming out all four feet (if infected) and then bandaging after trimming. This can take two hours and also helps solidify the team. The trimming produces a lot of blood and farriers should have a veterinarian on hand when they cut tissue that produces a lot of blood. Veterinarians are most effective when they can collaborate with the farrier, and advise treatment on the spot. Vets usually preform this function with the horse standing and tranquilized. Blood flow is controlled by using a tourniquet on the leg. Liquid nitrogen is used to freeze the tissue while trimming. Other veterinarians use electrocautery units for the same effect.
Callout: Any procedure that reduces blood flow and increases the cellular exposure greatly reduces the number of treatments required to remove all infected tissue.
Canker
Medications
Since we don’t know exactly what bugs cause canker, it seems presumptuous to claim that we have a cure, but one of the drugs receiving sponsorship by all of the authorities are the same ones used to treat pimples on a teenager’s face (benzoyl peroxide in 20-percent acetone), and metronidazole, a drug that kills anaerobic bacteria, mixed with the antibiotic, tetracycline, to produce a paste.
After trimming the canker-infected feet, they are sprayed with a wound wash that kills both bacteria and fungi. Then the benzoyl peroxide and metronidazole-tetracycline pastes are applied. All of the treated feet are then wrapped in a waterproof bandage and left on for three days. Moisture on the canker-infected feet, regardless of the cause, appears to inhibit the canker curing; this even extends to soaking in epsom salt or betadine, so it’s imperative the infected areas are kept dry.
The last step may be the most critical for curing: Continue to trim until all evidence of any infected tissue has been removed. To consider a case “cured” it should stay clean for one year. If symptoms persist, the horse should continue to be treated with bimonthly trimmings.
One horse treated for canker was checked two years later, and since being treated he had won $8000, two saddles and was retired sound at 16 years old. The only symptom two years after treatment was the frog on one foot was smaller. Unfortunately, not all cases are successful.
Too Little Too Late
The pictures taken in this section of the article demonstrate how important is to diagnose and prevent the deep-seeded invasion of tissue that occurred in this case. The entire frogs in all four feet were barely attached and the hoof was detaching at the cornet band. The extent of the surface tissue infected is an indication of how extensive the deep tissue is infected. When this mare was put down we dissected out the tissue and verified that canker can kill if left untreated. The origin and full duration of the infection is unknown since the mare was purchased within the year of the canker diagnosis, but the tissue examined and analyzed at autopsy supported the owner’s conclusion that treatment would be too prolonged and painful for the horse to endure, hence the decision to euthanize.
The Best Way to Defeat Canker
Start with this basic truth: Canker is not thrush, and you cannot achieve the end result you want by using the surface sulci cleaning medications that reverse thrush. Thrush kills tissue but canker promotes cellular growth similar to proud flesh buried in the normal tissue. The path leading to canker cure requires the following:
Diagnosis of the infected tissue
Repeated removal and debridement
Use of benzoyl peroxide ointment and metronidazole paste
Repeated bandaging.
Bimonthly trimmings to assure that you finished the job
Finally, remember to seek professional help you can trust, and be vigilant in your attention to this disease. It won’t disappear with any quick method, but it is possible to treat and for your horse to survive this stubborn, and serious condition.
About David Jolly, DVM
Born in Richmond, Virginia. Jolly graduated from Virginia Tech with a degree in Animal Science in 1964. He attended Texas A&M Veterinary school and graduated in 1968 with a degree in veterinary medicine. Dr. Jolly has been an Equine practitioner ever since, and has worked at racetracks in West Virginia, Maine, and Arkansas. Since 2001, Dr Jolly has focused on Equine Catastrophic Wound Therapy, pioneering the use of platelet-derived growth factors in healing wounds at Step Ahead Farm and Training Center in Hot Springs, Arkansas. The product name and contact here
For extensive pictures and to help diagnose canker, visit Dr. Jolly’s website: www.Stepaheadfarm.com and pull up the case of the month and also look at the other canker cases that I have treated.
