CORNS: AN UPDATE JANUARY 2023
Superficial digital flexor tendonectomy (SFT) is now the accepted best treatment for corns and is performed in UK veterinary schools, veterinary practices and similarly around the world. In the 4.5 years since its inception and with my experience of over 600 surgeries, the technique has evolved into removing a short section of the superficial digital flexor tendon at the metacarpus/metatarsus. Technically this is called a tendonectomy.
Short and long-term results continue to be excellent, but a small number of dogs have a recurrence of the corn several months after the original successful surgery due to the tendon reconnecting. Fortunately, these usually respond to repeat surgery. This is the reason for instigating the tendonectomy modification.
LIVERPOOL UNIVERSITY CLINICAL STUDY
I am collaborating with Pippa Williams and Professor Eithne Comerford at the University of Liverpool with the aim of evaluating the reduction in pain at 12 weeks and 12 months post- operatively and then comparing the dog’s general life and well-being before and after surgery.
This project is now closed to further participants as the required numbers have been reached but the data will still be collected for another 12 months before analysis and submission to a peer-reviewed veterinary journal. The results are independently assessed but as I am blinded as to its progress, I am unable at this time to give further information. A big thank you to all who have submitted cases.
Together with Richard Doughty we have had two articles published in the UK Vet Times 51 (19): 10-14, 2021 and the North American Veterinary Practice News - https://www.veterinarypracticenews.com/corns-in-dogs-september-2018/
More recently we have a peer-reviewed paper published in Australian Veterinary Practitioner Vol 52(3) Sept 2021 followed by a clinical techniques article in the prestigious Veterinary Dermatology Journal:- DOI: 10.1111/vde.13117
An updated article has again been published North America Veterinary Practice News: https://www.veterinarypracticenews.ca/tendonectomy-offers-relief-for-chronic-corns-in-sighthounds/
FLEXOR TENOTOMY FOR THE TREATMENT OF CORNS
A corn is a hard circular area of thickened pad tissue that occurs in the toe pads of sight hounds and is found mainly in the pads of the central toes in the front limbs. It causes severe lameness especially when walking on hard uneven surfaces with the dog becoming reluctant to go for walks or play.
Corns are caused, as in humans, by repeated mechanical trauma or pressure on the pad. They are definitely not caused by a virus or by foreign body penetration. If that pressure is reduced the corn will grow out and disappear.
There are many different treatments that are advocated including ointments to soften, burn out or dissolve the corn; conservative management involving regular paring and protective foot ware, and surgery by either hulling or excising. Even if the corn has been completely removed it will recur in more than 50% of cases within a year because the mechanical pressure has not been addressed. This new treatment removes pressure on the pad by cutting the tendons under the toe (flexor tenotomy).
The original surgery involved cutting both the deep and superficial digital tendons under the toe through a small incision causing the toe to flatten and the nail to stick out losing contact with the ground. If the dog is lying on its side with the leg extended the toe will be elevated by about 30 degrees.
This has now been modified by cutting only the superficial digital flexor tendon (SDFT) just above the foot. A further modification involves removing a short length of the tendon. The nail again sticks forward but remaining in contact with the ground and the toe is not completely flattened. In both procedures the corn is not pared or removed.
Although the results of both procedures are comparable SDF tenotomy is less likely to cause concussive pain under the toe on rough ground and aesthetically it looks better.
Recovery is rapid and by seven days post surgery most clients have reported a great improvement in both lameness and demeanour. These dogs want to play and exercise!
By eight weeks almost all corns have grown out leaving a normal soft pad with no or slight lameness.
Frequently asked questions:
1. What is the recovery period from the surgery?
The dressings are removed after 24 hours and it is recommended that there is lead exercise for a further 10 days and then free exercise. Lameness is dramatically reduced by day 2.
2. My dog has a corn on a central toe but the adjacent toe has been amputated. Is tenotomy a suitable procedure in this case?
Yes with a SDF tenotomy. A full tenotomy requires the support of adjacent digits to prevent contact of the skin under the toe with the ground and so is not suitable.
3. By increasing the weight distribution onto the other pads is there a further risk of subsequent corn development?
Some dogs have a genetic tendency to develop multiple corns and at present there is no evidence to support this assumption. Possibly there is an increased risk of one developing in the same foot but there are not enough cases to determine this.
4. Will the corn grow back in the future?
This is highly unlikely.
5. Can more than one foot have the surgery in the same session?
Yes with no adverse effects on the patient. All four feet have had tenotomies in one session.
Results of the original completed study
91 dogs with 149 corns:
Over the course of the study 39 dogs had more than one corn (43%)
Whippet = 17 Greyhound = 70 Lurcher = 4
Full tenotomy results:
• 86 dogs with 113 corns
• At 8 weeks 12 dogs had slight lameness and 54 dogs had no lameness
SDF tenotomy results:
• 27 dogs with 37 corns
• At 8 weeks 6 dogs had slight lameness and 20 dogs had no lameness
• Overall 97% dogs had slight or no lameness.
12 month follow up on 30 dogs
• 1 dog had moderate lameness, six dogs had slight lameness and 23 dogs had no lameness
Owner satisfaction: all very satisfied with the outcome reporting that the dogs were much happier and more willing to exercise.
• All corns had grown out
• Racing dogs returned to racing.
Follow other people's experiences on the dedicated Facbook page: Flexor Tenotomy: Greyhounds With Corns