Corns

It was only a matter of time before I posted on this topic. Most greyhound owners are at least aware of, if not well acquainted with the tricky affliction that is corns. Eddie has been spared this malady, but Cassie has had a couple of mild corns previously.

The first signs of a corn is usually lameness on hard, but not soft, surfaces. Corns appear as round, sometimes whitish, domes or discs on the paw surface. Although it is said that corn are often misdiagnosed as skeletomuscular problems, I have found that vets often are aware of the problem in greyhounds. It is worth considering corns when faced with otherwise unexplained lamenss, and dealing with them as soon as possible, since they can lead to secondary problems, as the dog modifies its gait due to the pain.

Examples of corns on
greyhound footpads.

Commonly thought only to occur only in greyhounds, corns, or circumscribed hyperkeratotic lesions, are found in other breeds too. However, it does seem that they are most problematic in greyhounds and lurchers, due to the lack of cushioning fatty tissue in their toe pads making the condition more painful. In fact, it is also suggested that this lack of fat is one of the reasons greyhounds tend to get corns far more often than other breeds.

Viral infection and foreign bodies in the pad are also cited as possible reasons, but mechanical pressure is likely to be if not a causal then at least a significant contributory factor in the formation of corns. Corns usually develop in the centre of the two middle, weight bearing, toes of the paw, and more commonly on the front paws, which take the most weight in a greyhound. This seems to indicate that pressure on the pad from the toe bone is crucial to the formation of corns in greyhounds. 

In humans, corns usually develop on feet due to mechanical pressure, such as ill-fitting shoes or protruding bones. The difference between corns and the simple thickening of the skin known as a callus, is that in a corn a hard plug of keratin (skin tissue) is formed, pressing into the skin and underlying nerves, making it potentially very painful when under pressure. Corns are fairly easy to remove in humans, but tend to recur. 

I have been previously been able to deal with corns on Cassie's paws myself. I soaked Cassie’s foot in epsom salt solution (traditionally used to “draw out” corns, foreign bodies and infections in humans as well as horses and dogs), and then filed down the skin on the pad until I could see the corn kernel clearly. When possible I then hulled the corn using a large gauge surgical needle (which works as a little sharp spade). Sometimes would have to soak and file the foot a few times, with a couple of days break in between, before being able to get the corn out. One corn came out on its own, during a walk, after a few times soaking and filing.

Many vets will use a similar technique, working the corn out with a scalpel or a dental root elevator. Often this can be done without much discomfort to the dog, but vets can and do sedate some dogs to make the procedure easier.

The dental root elevator technique. Click to enlarge. 

This time, however, my usual technique didn’t work. There was hardly any sign of the corn on the pad. This looked more like a lesion from a bit of glass or something. I managed to extract some corn tissue from the site, which did seem to alleviate Cassie’s lameness somewhat each time. I kept on having to repeat the procedure though, without being able to extract the whole corn kernel.

The vet advised that surgical removal would probably be necessary, but I chose to wait a couple of weeks, as I was going away and did not want to leave post-op care to the people looking after my dogs. When I came home, Cassie was much worse, however. She was almost constantly lame on the leg, even in protective booties, and even on soft ground.

Cassie was also getting pretty sensitive about me touching the foot. Usually she is quite patient and allows me to bother her corns with minimal grumbling. Now she was screaming and snapping. She was obviously in quite some pain. It seemed clear that surgical removal under general anesthetic was the way to go.

The operation was fairly quick – she was under for less than half an hour. However, the corn removed was a whopper, and deep. It had grown inside the pad, and trapped nerves against her toe bone. No wonder she was in pain. Her pad had to be stitched together with non-dissolvable suture, which will stay in for two whole weeks. She is on-leash only for this time, too, making sure the pad gets to heal.

The excised corn. Note how far below the
hard skin of the pad the corn extends.

The stiched pad. 

I am not sure why this corn grew – or moved? – inwards, into the flesh of her toe, when many grow outwards, in the harder outer layer of the pad, making them easy to remove. I wonder whether my interference had anything to do with how the corn developed. Ilaria Borghese, president of Thera-Paw and guru on corns, in her widely consulted article, also suspects intervention may be detrimental to the development of corns, especially if using salicylic acid products marketed for human corn removal. 

I have indeed considered but decided not to try these products, because I am worried I’d do more harm than good. There are also reports of a successful technique using duct tape, but I have not tried this. In my opinion, considering the that mechanical pressure seems to be the best contender for the cause of corns in greyhounds, perhaps prevention is better.

If the theory that the lack of fat in the greyhound foot pads causes corns is right, then we could say greyhounds have ill-fitting paw pads. Like in humans, corns will recur if the pressure that caused them in the first place is not dealt with. Unfortunately, unlike shoes, paws cannot be changed for a softer, more comfortable pair. The problem of corns, if a dog is afflicted by them, is therefore usually chronic or recurring. Whatever way you treat the corn, if the underlying mechanical cause is not addressed, they will most likely come back. The long term success of surgical removal is not very good - over half of excised corns return one to three years after surgery according to a study - so I am half expecting Cassie's corn to reappear at some point, although I will try to prevent it. 

The easiest way to prevent recurring corns is to use padded shoes on dogs with a history of the affliction. The best ones I have found are the Thera-Paw boots (for UK distributor click here). A more drastic measure is to partially or completely amputate the affected toe. Some studies have found this to be more successful than any surgical removal of corns, while others report that corns return on remaining toes (which presumably now take the pressure when the dog moves). An experimental treatment involving the implanting silicone gel cushions in the pad has been tried but doesn’t seem to have moved on to any clinical use in canines.

Thera-Paw cushioned boot.

I expect the gait of individual greyhounds, which affects how weight is distributed on their pads, is relevant to whether any particular hound develops corns or not. I wonder, therefore if correcting other possible skeletomuscular issues, using pain relief, physiotherapy and other relevant therapies, may aid dogs with recurring corns. 

As Cassie has a history of corns, and the recently removed one is likely to recur, I am thinking of having her wear her Thera-Paws any time we walk for any length of time on hard surfaces, taking it off only when she has a run-about on grass (they don't tend to stay on when she reaches 5th gear!).

I know many greyhound are affected by corns, and would love to hear from you if you have any experience with corns. Any miracle cures? A novel way of preventing corns? Please leave a comment!

Sources and Links:

I F. Borghese, Corns and Warts, http://www.therapaw.com/Docs/cornandwartarticle.pdf

Carol L. Machery, William E. Feeman III, (2006) Using a dental root elevator to remove footpad corns in dogs: Two practitioners' experience, Veterinary Medicine, December 1, 2006. Access online: http://veterinarymedicine.dvm360.com/vetmed/Medicine/ArticleStandard/Article/detail/392957

M. J. Guilliard, I. Segboer, D. H. Shearer, (2010) Corns in dogs; signalment, possible aetiology and response to surgical treatment, Journal of Small Animal Practice 51, 162–168

S. F. Swaim, T. Amalsadvala, D. B. Marghitu, E. A. Sartin, J. A. Hudson, E. D. Stoenescu, Pressure Reduction Effects of Subdermal Silicone Block Gel Particle Implantation: A Preliminary Study, Wounds 16:10, 299-312.

Corns in humans: http://www.bupa.co.uk/individuals/health-information/directory/c/corns