The Cone Of Shame

A variety of wound protection options and devices are available to prevent self-trauma following injury or surgery with canine patients. This article discusses various features of these devices that should be considered by the veterinary surgeon or nurse when choosing a device for a patient.

Before thinking about the options that exist for wound protection, the clinician should try to reduce the need for these products in the first place.

Patients will normally interfere with wounds because of pain or skin tension, so the need for postoperative wound protection is greatly affected by surgical technique, suture technique and quality of analgesia. Postoperative checks should include pain assessment and medication plans should be adjusted to take this assessment into account.

Wound protection devices can be divided into various groups:

  1. Devices that cover or enclose the head.
  2. Devices that restrain the neck, preventing bending of the neck.
  3. Shirts or shaped covers that cover the affected area.
  4. Bitter sprays or self adhesive strips to make licking unpleasant.

Devices that cover or enclose the head:

‘Lampshade’ or Elizabethan collars were first patented in 1962 in the United States.  They are probably the most effective devices for complete prevention of self trauma in dogs, but are at the same time the most unpopular with owners.

Various designs of Elizabethan collar exist and it is useful to consider the various aspects of these designs in order to choose the correct option for your patients.

  1. Collar diameter.  This is what creates the majority of the problems.  The edge of the collar should protrude beyond the end of the muzzle in order to provide protection, but this tends to create a very wide cone.  This is especially noticeable in large breed dogs where the cone diameter can be impracticably large.  This prevents the dog from navigating in its environment and also weakens the collar so it tends to flop around the head.     Sufficient space should be left between the collar and the head to allow good ventilation and prevent panic.  Some designs have been adapted to reduce the collar diameter to a practical level while still maintaining a decent air space around the head.  Collars can be shortened for use with eye or facial injuries, and then strengthened with a strip of fabric tape around the external circumference.
  2. Peripheral vision.  It is not generally appreciated that a significant part of the vision of a dog is peripheral.  Collars that reduce peripheral vision should be avoided as this is likely to make things worse for the patient.  Fabric construction tends to be worst in this regard, although some fabric designs have widened the cone so much that it restricts vision less.  However, this does mean that very wide diameters are necessary to give protection (see 1).   Some plastic collars have deliberate tints, prints or surface patterns applied in order to make them more attractive to owners, but these are again likely to restrict peripheral vision.  Any unnecessary printing or patterns should be placed behind the field of view of the dog.  Collars made from a clear material such as PVC or polypropylene, tend to restrict vision the least.
  3.  Ventilation.  Anecdotally the use of an Elizabethan collar can increase the risk of skin and ear infections.  Several collar designs have incorporated ventilation slots or perforations to improve airflow.
  4. Connector tabs.  All designs incorporate some type of tab (cut from the collar material), Velcro, or additional connector to complete and secure the cone shape.  Tabs should be designed so that they are easy to assemble, but they should also be difficult for the dog to undo.  Ideally, they should be re-usable – some tabs are easy to put together, but are very difficult to undo without breaking them. Some designs of connector are apt to break or come apart during use.  Tabs and connectors should be able to withstand the collar bending or deforming without coming apart and the best incorporate some kind of integral locking mechanism that is very difficult for the dog to undo while still being easy for owners or vets to handle.
  5. Connection to the collar.  It is useful for an Elizabethan collar to have an attachment to fit a dog’s collar.  One make is designed to do without this attachment but it is generally useful to have this option as it can increase the attachment security, especially in long necked dog breeds..
  6. Softness and impact absorption.  A simple plastic cone shape is poor at absorbing impacts as the shape transmits the force with very little bending and energy absorption.  2 design improvements are available that modify the basic cone design :
  • Rubber or fabric strips incorporated into the inner and outer circumference of the collars.  This reduces the impact forces on the neck of the dog and also cushions the blow when they run into the back of your legs! 
  • Another design uses a folded angle in the cone shape, which creates a shock absorbing profile, achieving a similar effect.  This also has the advantage of reducing the outer diameter of the collar significantly. 

Both techniques confer a big advantage in comfort and practicality in use and make it easier for owners to accept the use of a collar.

  1. Structural strength.  A number of fabric collars now exist of various designs.  Most of these incorporate strengthening ribs to prevent the collar from being folded over easily.  Some have foam inserts to provide additional strength.  These designs are often more acceptable to owners, but they are much easier for a dog to push against and fold over than a plastic Elizabethan collar, especially in the larger sizes.  Cleaning can also be difficult and the foam or quilted designs may have poorer ventilation than some other collars.  Dogs with these collars in place should be monitored closely as they generally lack the structural strength of the plastic Elizabethan collars.

T-shirts and shaped body wraps:

These products enclose the wound area with a cover material, which is designed to be relatively easy to change while being difficult to remove by the dog.   However, saliva borne bacteria can still strike through the material if licking is severe, and dogs are physically able to bite or otherwise lift off the fabric if they are sufficiently motivated.  Some of these products will lose their shape and ability to stretch after washing which makes it difficult to maintain hygiene over longer wound management periods.  With some hair types, you can get knots forming beneath the fabric, so grooming is important when the shirts are changed to prevent discomfort.

They are not appropriate for all body parts, but can be extremely useful to hold a dressing onto the  ventral abdomen where conventional bandaging is difficult to maintain.    They are much more acceptable visually than other protective devices, but because they can be less effective, should be used with care.  It is worth considering their use during periods of good monitoring (e.g. during the day) with an Elizabethan collar used during the night.

Neck collars or braces:

There are a number of versions of these products on the market now.   These devices are not suitable for long necked breeds such as greyhounds or whippets as their necks are flexible enough to get around the brace.  Inflatable or foam ‘doughnut’ shapes now predominate, and these products prevent the dog reaching around to lick certain areas of the body, but their protection is relatively limited to the cranial abdomen, thorax and proximal limbs.  Distal limb injuries and caudal abdominal injuries receive less protection. 

These products should not be used in patients with neck pyoderma as the reduction in ventilation to the skin is likely to make the skin disease worse. Some of the inflatable designs have a poor quality design leading to lots of punctures and a great deal of dissatisfaction on owner discussion boards.  They should be monitored for failure very carefully indeed, especially in the early phases of wound healing.               

Anti-lick products:

These rely on a variety of bitter chemicals, either impregnated onto a self-adhesive backing strip, formulated into a spray, or directly incorporated into a bandage weave. Results are variable depending on the persistence of the patient and the relative strength of the formulation.  It would not be sensible to rely purely on these products for anything other than minor wounds unless the patient is very carefully monitored.  However, these products can be very useful when combined with bandaging techniques, to prevent interference with an otherwise well applied bandage.   The adhesive on some makes of strip is not completely dog proof and it can be useful to further secure them with adhesive tape.

There are no peer reviewed clinical trials directly comparing the results from different products, and such a trial would be very difficult to set up.  Because of the lack of evidence-based information on this subject, a vet or nurse should consider what factors are relevant to the patients and clients that they work with and choose appropriate products to suit these factors.