Sometime during their lives, most animals require some type of surgery. Often it is a neuter or spay, but other abdominal surgeries or mass removals are also common. In most cases, when an incision is made, it is not only made through the skin, but also through the deeper layers of tissue. The subcutaneous layer composed of fat and connective tissue, and the muscular layer all lie underneath the skin. All tissue layers must be close to allow for proper healing.
Closing an incision
To provide the best healing and most support, all three layers (muscle, subcutaneous and skin) must be closed separately. The skin incision may be closed with sutures, staples or surgical adhesive (commonly referred to ask skin glue). The type of closure used depends upon many factors, such as the site on the body, the activity level of the individual pet and the presence of other factors that may delay wound healing.
Suture materials
The threadlike material that may be used to close an incision is called suture material. However, all suture materials are not interchangeable.
Some suture is absorbable, meaning that the body will break down the material over the course of several weeks. Absorbable sutures are most commonly used for the muscle and subcutaneous layers, but can also be used to close the outer skin layer of some small animals. The advantage of this type of skin closure is that it is more difficult for the animal to remove the stitches by licking or scratching at the site, and that an appointment to remove the stitches is not necessary.
Nonabsorbable sutures are not broken down by the body and must be manually removed. Nonabsorbable sutures are commonly used to close an incision in the skin, but they must be removed days to weeks after a surgical procedure.
Staples and Adhesives
Staples may be used internally to permanently clamp a particular type of tissue. When used to clamp off small blood vessels, the staples are referred to as "vascular clips." While most commonly used to close the skin, staples may also be used to close an incision in the intestine or stomach. Staples and clips are made of metal, so those used internally will remain there for the rest of the animal's life. Those in the skin will need to be removed using a special staple remover instrument.
Surgical adhesive (tissue glue) may be used to close very small incisions that are made in the skin. The glue binds the two skin edges together and will eventually be removed by the body or sloughed off.
Causes of Delayed Healing
The healing of the body is remarkable. Usually in seven to ten days, the incision has healed enough to withstand considerable stretches and tension. An incision heals from side to side, not from end to end. This means that a four-inch incision will not take four times as long to heal as a one-inch incision, but rather that both will heal in relatively the same amount of time. However, some common factors can delay normal incisional healing.
Excessive Activity
Although sutures and staples are strong, if an animal moves in a way that puts tension on them, the tissues will take longer to heal and the sutures may even pull out. This is similar to a piece of clothing that can be torn open at the seam if the cloth on both sides of the seam is pulled apart. For this reason, animals should be kept quiet and are usually not allowed to run or jump until the incision is healed. For most surgical procedures, this exercise restriction lasts for 10 to 14 days.
Licking or Scratching
Animals that lick or scratch at an incision can actually work the incision open. Elizabethan collars (also known as e-collars or cones) may be placed on the animal so that they cannot reach the incision with their mouth. Other collars, such as No-Bite collars or inflatable "donut" collars can be used to prevent an animal from reaching an incision to lick. Bandaging or placing a sock on the hind foot may help to reduce the risk that scratching will open up the incision.
Infection or Fluid Accumulation
An infection at the incision site slows down healing and causes absorbable sutures to break down more rapidly. An accumulation of fluid or pus around the incision also puts extra tension on the sutures, increasing the risk that they may pull out. To prevent infection, it is important to keep incisions clean and dry, and prevent a pet from licking at the incision. Drains may be needed to allow for the continuous passage of any accumulating fluid, particularly in cases of skin trauma, such as bite wounds. Prescription antibiotics are often necessary, should an incision become infected.
Reaction to the Suture Material
Some animals may have a reaction to the suture material, resulting in inflammation or very small accumulations of pus around the suture material. If the suture material is in the muscle or subcutaneous layer, a small drainage area through the skin may develop. In most instances, the reaction does not cause a problem and disappears once the sutures have been broken down by the body. In other cases, the incision must be re-opened and the sutures replaced with a different type of material.
Medications and Health Conditions
Some medications are known to slow down the healing process, with the most common culprits including the corticosteroids (e.g. prednisone or dexamethasone). Likewise, some nutritional deficiencies can delay healing. Certain health conditions, such as kidney or liver failure, protein deficiencies, diabetes, cancers and hormonal imbalances may also result in delayed healing.