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The medial canthus is the technical term for the inner corner of the eye (the outer corner being the lateral canthus). The need for surgery to the medial canthus is rare in cats, but when it arises the procedure is within the capabilities of the vet in first opinion practice.
The most common indications are reconstruction after removal of a tumor from the eyelid margin, or because of a congenital defect meaning the cat has poor eyelid anatomy, which leads to discomfort.
It's crucial to assess the patient's anatomy while they are conscious. This is because the head position can influence how the eyelid sits against the eye, and make a difference to how much tissue is included in the surgery. If necessary, local anesthetic drops are instilled into the eye, to stop the cat squinting due to discomfort. This allows for better surgical planning.
The cat is then anesthetized and placed with the affected eye uppermost. The hair is clipped from that half of the face, and lubricating drops placed in the eyes. The skin is aseptically prepared and the area draped up.
The surgeon plans the surgery to resect the tumor or excess amount of skin. To repair the skin deficit (from tumor resection) may mean creating a skin flap from the area of the medial canthus. Likewise, a sliding skin flap may be created at the medial canthus in order to 'slide' away the excess skin.
Once the surgeon is happy with the positioning, the skin is sutured in place using very fine absorbable sutures.
Surgery to the medial canthus facilitates a permanent change of the anatomy of the area. In the majority of cases, the only other option is medical management of the symptoms caused by maligned anatomy. In the case of ectropion (out turned eyelids) this is likely to be lubricating eye drops instilled into the eye several times daily. Where cancer affects the eyelid margin, taking no action will eventually mean gross deformation of the face and euthanasia.
The eyelids are very sensitive and systemic pain relief is essential postoperatively. The cat must wear a cone in order to protect the surgical site from rubbing or self-trauma. The absorbable sutures are not removed, instead, the cone is taken off after 10 to 14 days and the cat will rub away the sutures during normal grooming activities.
The eyelids will be grossly swollen in the first few days after surgery, and it is only after this initial swelling has gone down that the success (or otherwise) of the surgery will become evident.
The cost of surgery varies widely depending on the reason. For example, closure of the medial canthus due to a tumor removal will be just part of a bigger procedure. As such, the cost will be that of the tumor removal, which is to be expected to be around $600 to $1,400.
The success of the end result depends on good surgical planning. The effects of surgery on the medial canthus are permanent, but when done well it can save life or vastly improve the quality of life.
Squamous cell carcinoma is strongly linked to repeated sun exposure. The risk is pronounced in white coated cats that lack protective melanin pigment. Therefore, white cats should be kept out of the sun, or their extremities protected with pet-safe sunscreen. Unfortunately, this can be hard to achieve, especially when so close to the eye itself.
Cat born with ectropion should not be bred from as they are liable to pass the genes onto their offspring who may also have ectropion.
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