Corns and Warts

Seed warts/Corns in Greyhounds

Jill Hopfenbeck, DVM

These recommendations represent my personal experiences treating “seed warts”(more properly called corns) in greyhounds. I’ve treated 15-20 dogs over the past 8 years, including one of my own, who got me thinking about the problem.

Diagnosis: this is not a difficult thing to diagnose, as long as you know what to look for. The dogs are often quite lame, and I often see dogs who have had extensive x-rays performed when the lameness was due to this problem. One tip off is that these dogs are MUCH more lame on pavement versus grass (hard versus soft surface). Also, they generally do not respond at all to pain killers or anti-inflammatories, since this is at heart a mechanical lesion (sort of like having a stone in your shoe). I carefully examine the bottoms of the pads on the affected feet, and the corns are visible as oval to circular, 2-3 mm whorl patterns, directly under the end of P2 (2nd toe bone). In the early stages, this circular lesion is difficult to see—you can often visualize it better if you wet the bottom of the pad. On palpation, this area usually feels hard compared to a normal pad, and the dog is often painful if the area is squeezed. Later on, these corns can get quite large, with the keratin centers raised off the surface of the pad.

Here’s the rational:

This is a problem that occurs (virtually) only in greyhounds. If the dog lives in a multi-dog household, only one dog is affected. This argues against an infectious cause (not a virus). The lesions almost always occur on one of the central, weight-bearing toes, in the front/center of the pad, directly under the end of P2, the 2nd toe bone. I believe that this is at its heart a mechanical problem. Due to their lack of subcutaneous tissue/padding, and possibly other mechanical factors, this bone is too close to the underside of the pad, and a keratin “callus” forms as a result. This argues against surgical removal, as in most cases this only removes more of the protective tissue and exacerbates the problem. It is important to note that as a mechanical problem, “lifestyle” changes are also very important to reducing the severity of the corns—long walks on hard surfaces should be eliminated, and I recommend the use of some sort of well-padded bootie on the affected feet (Thera-Paw booties are the best that I’ve seen, and may be ordered from Jorgensen Laboratories by veterinarians).

I became interested in this problem when I adopted an old (11 ½ year old) greyhound (returned to the adoption group by another family). According to her medical record, she had gone to the vet yearly for vaccinations, teeth cleaning, and to have the “seed wart” removed from her right rear foot. Shortly after she came to live with me, she fractured a toe on that same foot. After wearing a splint for 6 weeks, lo and behold, the corn was gone, never to return for the next 3 years of her very long life.

Here are my usual recommendations:

If there is just one rear foot (or sometimes a single front foot) affected, I often try to convince the owner to splint the foot for 6 weeks. I change the splint every 2 weeks in order to make sure that there are no problems under the splint (greyhounds have VERY sensitive, fragile skin) and to check progress. At each splint change (no sedation needed, just a cushy blanket to lay on on the exam table) I generally try to curette out as much of the hard, insensitive keratin as possible (described in more detail below).

If the owner will not accept a splint, or there is more than one foot affected (as is often the case), I start by using a small curette and/or a scalpel blade to remove as much of the keratin as possible. The curettes I use are 2-3 mm in diameter, and look like little melon-ballers. I do this with the dog gently restrained on a blanket on the exam table, and it does not seem to hurt the dog. I also use a human (Dr. Scholl’s) callus pumice stone (white, elongated, on a handle) to further smooth down the pad. I then prescribe a product called Kerasolv (available through DVM Pharmaceuticals, a common veterinary supplier) for the owner to massage in daily. The active ingredient in this product is salicylic acid, which is also used in some human wart-removers (I have a couple of clients who are experimenting with little patches soaked in salicylic acid which are sold in pharmacies for children—stick to the pad, perhaps stays in contact for longer). The Kerasolv works best if the pad is hydrated first by soaking in warm water (or applying warm compresses).

It is probably best to recheck/curette these dogs every 2 weeks initially, but for my practice that is difficult, as the people are usually not local. I have often seen them on a monthly basis with good results. In addition to the Kerasolv, it is also important for these owners to do everything they can to provide padding on these feet, by wearing booties, eliminating walks on pavement, putting down carpets on hard floors, etc.

While corns are difficult to cure completely, dogs are often improved markedly on this regimen. I see several dogs who have had multiple surgeries performed (one who lost a toe due to surgical complications). The dog who is missing one toe has gone from having corns on 3 out of 4 feet, multiple toes on each foot involved, to a single corn on one foot (and that one is much less severe than it was). Owners report that the dogs are much more comfortable after the curetting (the “stone in their shoe” is smaller), and notice when it is time for another appointment. Given these dogs’ previous history, I count this as a success.

Jill Hopfenbeck, DVM
Sutton Animal Hospital
38 Oakhurst Rd.
Sutton MA 01590
508-234-8102

Corn, Callus, and Wart Information Gathered From the
North American Veterinary Conference
(Jan. 18-21, 2003)
2nd newsletter by Ilaria F. Borghese, MS, MA, OTR/L

News from the veterinary world gathered from the North American Veterinary Conference regarding corns, warts, and calluses was promising.

The following treatments are currently being researched for dogs with:

corns resulting from insufficient padding (fat) in the toe pad, and
corns resulting from excess internal pressure from the toe bone on the paw pad.

I spoke with Steve Swaim (Director of Wound Healing and Reconstructive Surgery at Auburn University). He told me that, according to the owners, Shadow continues to do well and to be without lameness on the paw affected with corns. Some of you may recall that Shadow was the “test case” greyhound for the silicone implant in the toe (to replace the lack of fat in the pad). The procedure involved a silicone block that was granularized and injected into the paw pad following the removal of the corn.

Dr. Swaim is also testing an arthoplastic procedure on greyhounds. This procedure involves removing the corn (which leaves a “pocket” inside the pad), shaving the toe bone, and filling the “pocket” with a silicone implant. So far, the results are positive, though they are limited to 2 test cases. When asking other veterinarians to comment on this procedure, I received mixed opinions about the feasibility of this technique.

Both procedures being researched by Steve Swaim are designed to provide a cushioned layer (mimicking a fatty layer) in the paw pad to absorb shock and to protect the pad from inner and outer pressure. Though these procedures are quite invasive, if they are successful, they have the potential to relieve lameness permanently.

I spoke with a podiatrist (treating humans – though now transitioning to the canine world), who filled me in on some techniques used to treat humans with painful corns. He informed me that collagen or fatty tissue was sometimes implanted into the painful toe to cushion the area.

When I discussed this “human approach” to treating corns with Dr. Swaim, he informed me that collagen implants can cause scar tissue build-up (a negative outcome since scar tissue is a component of corn material). Furthermore, Dr. Swaim believes that the fatty implants can produce similar results. When he removed fat from a greyhound (not an easy task) and implanted it subcutaneously (just under the skin) in a beagle (as a test case), the fatty tissue hardened into a lump. From his experiment, Dr. Swaim theorizes that fatty tissue will also harden if implanted into the toe of a greyhound.

I discussed these finding with the podiatrist. He believes that the “hardening” of the fatty tissue was caused by an immune-related response to foreign tissue (greyhound fat implanted in a beagle body). In conclusion, he does not believe that the fatty tissue would harden if taken from a greyhound and implanted into the same greyhound, since there would not be the associated immune-related response. Obviously, there continues to be some debate in this area.

The highlight of the conference was my talk with Dr. Alessandro Piras, an Italian veterinarian now practicing in Northern Ireland (and the owner of 12 greyhounds!!!). He is passionate about finding a way to help these affected greyhounds (2 of which are his own), and is working on a research study to look closely at the underlying cause of this disorder. He has some theories about the cause of corns, though it is premature to discuss them at this stage. Perhaps, when the time comes, we can all assist him with his research (e.g., with filling out questionnaires, providing medical records).

As for treatment of corns and warts with topical solutions, by the end of the conference, there was a growing body of evidence that showed that salicylic acid-based products (Kerasolv and most corn/wart removers) produce more harm than good. Though some of you have found success with these products, many veterinarians are beginning to feel that these products can ultimately aggravate the paw skin and lead to even bigger corns.

Most recently (October, 2002), a study was published in a human pediatrics journal concerning corns/plantar warts in children. The study showed that duct tape was more effective than salicylic acid in removing corns and warts. According to this article, duct tape placed over the affected area acted to deplete oxygen to the site and to kill the growth. Corns and warts deprived of air and sun exposure die, and the adhesive in the tape removes the deadened area. Furthermore, the researchers believe that there is something in the adhesive material itself that may help to increase circulation to the affected area and to stimulate the body's own overall immune response. The study showed that, not only did the tape-covered warts disappear, but so did the uncovered ones.

At the American College of Veterinary Surgeons meeting in 10/2002, an orthopedic surgeon (Dr. Bob Taylor from Animal Planet’s Emergency Vets) who has extensive experience with greyhounds and who is familiar with this study, encouraged me to try the duct tape for a 30-day trial on my dog, Tybalt. He instructed me to apply a small piece of duct tape directly onto the corn, then peel it off at night and immediately apply another piece, making sure that the tape does not cover the healthy pad.

Less than 3 months later, I find it hard to believe, but the tape worked (at least to some extent, though better than any other topical that I have tried). The duct tape helped to minimize the condition so that the corns are now much smaller and much more manageable. The corn was greatly reduced in size after about 6 weeks, as was Tybalt’s lameness. Tybalt walks well in the house now (for the first time since we adopted him!), and only needs his Thera-Paw gloves when going for long walks outside (he used to wear them all day long). I have been using the tape for maintenance, whenever the corn seems to bother him. I believe that Tybalt's corns are caused by insufficient fat in the toe pad and, to this extent, there is not much that can be done apart from surgery. But the years that I have spent dousing the corns with salicylic acid-based products and dremeling them out made the corns worse in the long run. I believe that the dremeling process and the acid caused a hyper-response in the skin of the toe pad, and made the corns grow larger in response to the irritation.

The duct tape procedure I used was different from that suggested by Dr. Taylor as Tybalt appeared to require a more aggressive treatment plan. The treatment plan I sued was the following: 1) Cut a tiny piece of duct tape (just enough to cover the corn) and place it directly over the corn. 2) Replace the tape every 3-5 days or sooner if the tape comes off (you will notice that the tape removes a dead layer of corn material when you take it off). 3) The dog may appear worse (more lame) for 1-2 days upon first application – I am not sure why, and it may be a coincidence, but this did happen to Tybalt. 4) Continue this procedure until the dog appears improved and the corn is smaller/disappears (it took nearly 2 months to hit our threshold). 5) Repeat the procedure if the dog's lameness due to corns returns (I have had to repeat the duct tape treatment twice though for only 1 week, since it took only 1 week for Tybalt’s lameness to resolve).

The other thing that has made a huge difference in Tybalt is a joint/arthritis supplements and I believe that joint support is critical for a chronically lame dog (since so much compensation is taking place in other parts of the body)..

{Please note that I am not a veterinarian, and that I am just offering information that I have gathered through conversations and through personal experience with my own greyhounds. I strongly suggest that you discuss any form of treatment with your own veterinarian.}