By Dr. Gary D. Norsworthy, DVM, Dipl. ABVP (Feline)
Originally published in Veterinary Practice News – August 2012
1 – Lesions in Difficult Places
Oral tumors are frustrating because most affected cats are presented for drooling, poor appetite or fetid breath. Owners typically think there is a dental problem that can be solved with a good teeth cleaning or a few extractions. They are shocked to find that an aggressive, malignant tumor is present and that it is beyond surgical removal or response to chemotherapy or radiation therapy.
The CO2 laser can permit tumor debulking and control for a few weeks. This gives the family time to deal with the impending loss of the cat (Figures 1A and 1B).
Eosinophilic granulomas occur in many locations, including the base of the tongue (Figures 2A and 2B). In this location eosinophilic granulomas can make eating very difficult for the cat and result in significant weight loss. Although some respond to anti-inflammatory medications, response can be slow.
An odontogenic tumor (epulis) is an uncommon gingival proliferation that occurs around the teeth (Figure 3A). It can be temporarily removed with the CO2 laser (Figure 3B); however, over time it will recur until the teeth are removed (Figures 3C and 3D). Removal of the tumor with the CO2 laser should be performed and immediately followed by teeth removal.
The CO2 laser permits rapid debulking with control of hemorrhage. In some cases, a hemostatic powder can be a helpful adjunct therapy for bleeding. This treatment is followed with anti-inflammatory drugs to complete the removal and prolong remission.
Facial tumors can be difficult to remove with conventional surgery because appropriate margins are frequently not possible. Figures 4A, 4B and 4C show a squamous cell tumor. The mast cell tumor did not recur; the squamous cell tumor recurred nine months post-operatively and was treated again with the laser.
Perilaryngeal tumors are not discovered until the cat develops respiratory stridor (Figure 5A). At this stage, open-mouth breathing may be present and the cat in a respiratory crisis. A video-otoscope can be a very useful tool in viewing this area and assessing the airway stricture. Biopsy forceps can pass through the working channel for tissue sampling.
The CO2 laser, with a special tip that goes through the video-otoscope, can be used to treat these lesions and relieve the immediate respiratory crisis (Figure 5B). The ultimate treatment will depend on the histopathologic diagnosis.
2 – Stenotic nares
Stenotic nares are often part of feline brachycephalic syndrome (Figure 6A). Opening the nares using conventional surgical techniques can be very difficult because of patient size. The CO2 laser can open them in seconds (Figure 6B). The results are predictable, making it a what-you-see-is-what-you-get (WYSIWYG) procedure.
3 – Entropion
This is a relatively uncommon ocular disease in cats, but it can result in chronic keratitis and recurrent corneal ulceration (Figure 7A).
A row of X-shaped strokes are made with the laser parallel to the lid margins, resulting in a rolling outward of the lid margin (Figure 7B). This is another WYSIWYG procedure. The final result after healing should be virtually identical to the appearance at the end of surgery.
4 – Ceruminous Gland Adenomas
These are unique tumors of the inner surface of the pinna and the external ear canal and arise from the cerumen glands (Figure 8A).
Although the tumors are benign, they are unsightly and obstruct the flow of air in the external ear canal, resulting in chronic otitis externa. The CO2 can easily vaporize the masses (Figure 8B). When healing is complete, the ear appears normal (Figure 8C). Unfortunately, affected cats form new masses over six to 15 months, so repeat therapy will be needed.
The CO2 laser has many applications for cats. It can offer options for therapy that are superior to other choices.
All Photos Courtesy of Dr. Gary D. Norsworthy, DVM, Dipl. ABVP (Feline)
Dr. Norswrothy, in practice for over 40 years, writes for a variety of veterinary journals and frequently lectures for veterinary associations. His Alamo Feline Health Center in San Antonio is South Texas’s only hospital limited to cats and the only one that offers a truly dog-free environment.