‘Hair of the dog that bit me’
Welcome to ‘dog hairs, foot pain and the pilonidal sinus’
A rare condition
Many of us like to keep animals and there are many benefits until you pick up some fleas that make you itch, or develop a respiratory problem after finding that you are allergic to your pet. But there is another common problem that often goes missing. In this article I hope to offer some background information and provide some self-help guidance.
The nature of hair being protein is able to penetrate the top layer of skin (epidermis). Having 5 layers of skin cells and being the thickest in the body this may seem surprising. However, that tiny dog hair, given the right angle, can penetrate the skin. The coarse hair is sharp as a needle.
Podiatrists Ivan Bristow and Andrew Boyle provide a case report of a pilonidal sinus in a 57 year old woman in the College of Podiatry’s journal (PODIATRY NOW – March 2020 Vol. 23;3:6-7). The article reminded me of my own experiences, first as a general practitioner in podiatry, and later as a podiatric foot surgeon.
Called to a home of the manager of a well known theme park, I examined his foot in his capacious kitchen. The little red mark under the ball of his foot had a dark middle. Using my magnifying glass it was clear that this resembled a hair. I could see that he had a dog. Was this a source? I used my finest forceps to clamp onto the hair. After a little resistance the thread like foreign object slid away leaving a thin clear fluid on exit. A local antiseptic dressing for 24 hours was used. I provided advice on what to watch out for in case of infection. All was back to normal and a problem avoided. My patient had acted swiftly having called the right person.
Foreign bodies arise where a penetrating object, alien to the skin, is sealed off as part of the body’s defense mechanism. We have special cells that make digestive enzymes and white blood cells to protect us. These special cells coat the intruder with an attractive substance making it a target for the scavenger cells. This coating allows cells to focus on the alien. Although the attack comes from the outside initially, deeper down and under the skin an almighty battle commences. This leaves a red sore swollen area which if left just goes from bad to worse. These pilonidal sinuses are worse in the foot because of walking pressure.
I can recall that one of my own patients more recently had a swelling between his toes that would not settle. I had to clear away the mound of red swelling, remove the mass of healed tissue and seek out the foreign intruder under anaesthetic . Given time, the scavenger cells are efficient at breaking down the hair. In his case little was seen, only the devastation left behind which was now my main crusade. Under a powerful microscope much can be deduced. Giant cells are found when wounds become chronic so they are easy to pick out on magnification. In serious cases wounds cannot even closed with stitches. To do so would seal everything in and so the wound is left to drain without stitches. Unsurprisingly these pilonidal sinuses can take a while to heal.
Bristow and Boyle highlighted the fact that their case required surgery. Last month I wrote about sore areas between the toes. Seeing the pilonidal case in my professional journal highlighted the problem of intruders between toes. This is one position in the foot where infection can travel quickly on account of the motorway network of lymphatic vessels. Patients in poor health (immune-compromised) are exposed to overwhelming problems. Those with leukaemia, undergoing cancer treatment and those with organ transplants add to others such as diabetics.
We should be reminded that a non healing wound can be caused by other foreign materials such as glass, wood and insect bites. A good magnifying glass can help. Removing objects can be carried out but take care of a hooked end. If pulled, this may do more damage, moreover part can be left in. Once the skin grows over, the intruder is easy to ignore unless the area is painful. All body hair can become involved with the skin and in the case of nails grow inwards down the groove. This is mostly seen in male beards, but body hair around the base of the spine is known to become a painful problem.
Self treatment for hairs & foreign bodies
- Wash and treat the area with an antiseptic first.
- Remove the object unless it has a hook or resists.
- Try not to break the end so it becomes buried.
- Cover the wound if possible to soften the area for 24-48 hours and re-examine.
- Make it comfortable by preventing shoe pressure with a padded dressing (if possible).
If after a few days the problem doesn’t settle see someone
The earlier you can deal with the problem the sooner matters settle
If you have had a problem in the foot do write and let me know. Read my own case history (here) when a tick decided to invade my skin whilst out walking. Or you can read my Monty Lyman’s book reviewThe Remarkable Life of the Skin Book Review covering all things skin.
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