Corn’s in Greyhounds

Absract:

"Corns" or "digital keratomas" are a frustrating and not uncommon problem of Greyhounds (racing or pet) causing significant lameness.  They are circular, firm to hard, flat or slightly raised thickened plaques, ranging in color from black to whitish, extending up from the central surface of the pads, usually on the areas that bear the most weight.  They may be secondary to either traumatic implantation of glass, sand or other foreign material or due to papillomavirus infection, or maybe both or idiopathic.  No one knows for sure. The papillomavirus has been isolated in only a few cases by immunoflourescent assay.  Radiographs have been taken to look for foreign bodies but these have rarely been found.

Unfortunately there is no current reliable good medical management for corns.  Therefore treatments range from “shelling” or “hulling” out the corns using a dental elevators; deep surgical removal (with varied success and significant recurrences); laser surgery (also with significant recurrences); human corn and wart removers with salicylic acid (ineffective), anti-viral therapy using systemic alpha-interferon or topical Imiquamod (Aldara) or Docosonal (Abreva); surgical neurectomy of the nerves to the affected toes due to counteract intractable pain; and toe amputation.

Discussion:

Various theories have been advanced regarding the etiology of Greyhound corns.  These include the lack of fat in the Greyhound pad associated with repeated trauma of racing and concussion, foreign bodies, chemical irritation associated with kennel disinfection, and viral infection.  The response seen with Aldara or Abreva and Interferon would suggest a viral etiology.  However it is strange that other breeds do not seem to be affected.  It is also difficult to explain how one hound in a house can be infected while the others seem to remain free.

Diagnostic approaches have included:

1.                biopsies that have come back as "hyperkeratosis and epidermal hyperplasia"

2.                radiographs have been taken to look for foreign bodies but these have rarely been found

3.                immuno-histochemistry in an attempt to demonstrate virus has been mostly unremarkable

Treatment approaches would seem to begin with a “shelling” or “hulling” procedure.  One can “dig” these corns out using a dental root elevator.  This can usually be done without any sedation, and provides instant relief.  Some suggest softening the foot with soaks prior to “shelling” procedure.  Some owners are able to performing this procedure on there own dogs.  Unfortunately there is a high rate of recurrence of the corns ranging at about a + 60% rate within 1 to 6 months.  Recently reports of using Abreva or Aldara cream in the hollowed out foot pad once daily for an indefinite period seem to have decreased the rate of recurrence, with some reports of resolution following repeated “shelling”.  Use of Interferon with doses ranging from 1,000 units daily to 1 million units 3 times weekly have been recorded with some favorable results. Some reports indicate that after stopping Interferon treatment after 2 months of use led to a relapse, so medication was re-instituted.  Interferon has been administered by injection and orally.  The use of humane wart or corn remedies (salicylic acid) seems to have given no improved results.

Surgical options include deep full thickness elliptical incisions into the foot pad to remove the corn in total.  The wound is sutured, and kept well padded to reduce additional trauma to the surgical site for at least 14 days.  Antibiotics are used.  However recurrences still occur.  Laser surgical techniques have not improved this rate of recurrence.  Amputation may have to be considered for stubborn cases, but because corns may occur on multiple toes one remains concerned to resort to this.   Local neurectomy seems a viable option for stubborn cases where lameness due to pain is a concern.

Soft surfaces such as grass and carpet as well as using padded boots (TheraPaws) improve comfort for these dogs.

References:

1. Veterinary Information Network - Carol Foil, Malcolm Ness, Harry Newman, Wendy Lorch, Therry Olivry  (NC State University), Sonya Bettanay, Kimberley Lower, Adi Nell
2. Carol Macherey
3. Dr Bill Freeman
4. Dr Alastair Smith – Sandown Veterinary Clinic- Sandown Greyhound Racetrack, Melbourne, Australia
5. Dr Suzzane Stack
6. Dr Gary Yocham