By Jacques-Marie Leclerc, DVM
For The Education Center
Romeo, a 5-year-old goldfish who lives alone in a 20-liter aquarium, was brought in for a consultation regarding a mass located close to the distal part
of the dorsal fin. The mass had been evolving for a few
weeks, during which there were no noted changes in
During the complete clinical check-up, Romeo was
alert and displayed a small balance disorder when
swimming. We noted the presence of two cutaneous
nodules on both sides of the dorsal fin. The smallest
one was on the left side measuring 3 mm, and the
other one was on the right side measuring 15 mm
Surgical treatment with a CO2 laser was suggested
to the owner.
CO2 laser cuts soft tissue by vaporizing water mol-
ecules, while limiting edemas and hematomas and
ensuring a better cicatrization and more comfort for
the animal. As it cuts, the CO2 laser beam shrinks the
blood vessels on the margins of the cut and reduces
bleeding, which dramatically improves visualization of
In addition, the destruction of micro-organisms
present within the surgical area decreases the risk of
We took the fish out of the water and administered
a natural gas anesthesia with carbon dioxide. We performed antibioprophylaxis with marbofloxacin ( 10 mg/
kg), combined with analgesia with buprenorphine ( 20
µg/kg) administered subcutaneously.
The nodules were removed with the Aesculight
CO2 laser (Figures 2 and 3). Laser power settings
were 6 W continuous wave (CW) with the 0.4 mm
focal spot size. We decided to preserve the fin during
this intervention. The fish was then replaced in oxy-
gen enriched water.
The subcutaneous tissue has been modified by the
presence of an unencapsulated tumoral mass, with
infiltrating growth, resulting from a fasciculated proliferation of fusiform cells. With such tumors, there is a
high risk of recurrence.
On day 15 we observed two suspicious zones, which
looked like a fibrosarcoma recurrence (Figure 4).
We vaporized the two nodules with the laser set at
8 W CW (Figure 5). We used a 1. 4 mm focal spot size.
We used the same protocol for anesthesia as during
the first intervention.
Controls at days 30, 45 and 60, revealed a perfect
cicatrization on the operative site with no traces of
fibrosarcoma recurrence present.
Between days 60 and 180, the owner could not
bring Romeo for observation. On day 180, we noticed a
new mass characterized by a bilateral invasion of the
dorsal fin base (Figure 6).
We decided to use the widest excision of the tumor, including the dorsal fin, and extend the resection margins to healthy tissues (“safety margins”).
The dissection was made with the laser set at 5 W
CW with a 0.25 mm focal spot size. The dissection
was made easily and quickly. No cutaneous suturing
After the dorsal fin excision (Figure 7 demonstrates
the excised tissue), the fish presented a noticeable
loss of balance for one hour (Figure 8), after which
the misbalance issue disappeared. Figures 9 and 10
demonstrate the quick healing process.
Four months after the last surgery, controls did not
show any signs of tumor recurrence. We noted that
the area of excision after cicatrization was covered
with smooth skin without scales (Figure 11).
We used the CO2 laser for its simplicity, speed and
safety, which allowed us to intervene by using a short
duration carbon dioxide anesthesia. This type of anesthesia was also safer for the fish.
In the course of the first intervention, we worked in
ad minima and performed excision by vaporizing the
wound margins. This proved to be insufficient. During
the second intervention, we performed a larger scale
excision. Thanks to the CO2 laser, we did not need to
make either cutaneous rebuilding or suturing. Without
the CO2 laser technology, we could not have obtained
such a good result.
Finally, this intervention has shown that the CO2
laser can be used in such unusual interventions. ●
Jacques-Marie Leclerc, DVM, is a small-animal practitioner in Le Cannet, France. He specializes in small-animal surgery. Dr. Leclerc discovered the CO2 laser six
years ago and was the first user of the NovaPulse flexible fiber CO2 laser in France.
Fibrosarcoma in a goldfish treated with CO2 laser
This Education Center story was underwritten by
Aesculight of Woodinville, Wash., manufacturer of
the only American-made CO2 laser.
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et procédures chirurgicales
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émetteurs dans la cavité ven-trale des truites communes
adultes (Salmo truita). Bull. Fr.
Pêche Piscic. 2005;374: 21-34.
2. Hadfield CA, Whitaker BR,
Clayton LA. Emergency and critical care of fish. Vet Clin Exot
Anim 10 (2007) 647-675.
3. Berger N, Eeg PH. Veterinary
laser surgery: a practical guide,
ed1, Ames, IA, 2006, Blackwell
Figure 1. Two tumors on both
sides of the dorsal fin prior to
first laser surgery.
Figure 5. Day 15—post-op view
of the vaporized nodules (second
Figure 9. Day 1 after the third
Figure 6. Day 180—recurrence of
Figure 10. Day 15 after the third
Figure 3. Post-operative view
Figure 7. Excised tumor (after
Figure 11. Four months after the
third surgery. No traces of fibro-
sarcoma are present.
Figure 4. Day 15 after first sur-
Figure 8. Imbalance after the am-
putation of the fin (post-operative
view after 3rd surgery)
Figure 2. Intra-operative view (first
surgery) showing laser handpiece
with adjustable focal spot size.