Percutaneous ultrasound-guided radiofrequency heat ablation for treatment of hyperthyroidism in cats.
OBJECTIVE
To determine efficacy and safety of percutaneous radiofrequency heat ablation for treatment of hyperthyroidism in cats.


METHODS
Prospective study.


METHODS
9 cats.


METHODS
Hyperthyroidism was diagnosed via clinical signs and high serum total (TT4) and free thyroxine (fT4) concentrations. One or 2 hyperfunctional cervical thyroid nodules were detected by use of scintigraphy and ultrasonography. If cats had 1 abnormal thyroid lobe, heat ablation was performed on that lobe; if cats had 2 abnormal lobes, heat ablation was applied to the larger lobe. Overall, heat ablation was performed 14 times in the 9 cats. Clinical signs and serum TT4, fT4, and calcium concentrations were monitored daily for 2 days after the procedure, weekly for the first month, and then monthly. Laryngeal function was evaluated and cervical ultrasonography and thyroid scintigraphy were also performed. Monitoring continued for as long as 9 months after heat ablation if a cat became euthyroid or until an owner chose an alternative treatment because of recurrence of hyperthyroidism.


RESULTS
Serum TT4 and fT4 concentrations transiently decreased after all 14 heat ablation procedures (< or = reference range after 10 of 14 treatments) within 2 days after the procedure. Cats were euthyroid for 0 to 18 months (mean, 4 months). Hyperthyroidism recurred in all cats. Adverse effects included transient Horner's syndrome (2 cats) and laryngeal paralysis without clinical signs (1 cat).


CONCLUSIONS
Percutaneous heat ablation as a treatment for hyperthyroidism in cats is effective transiently but not permanently.
Mallery
Kevin F
KF
Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Pollard
Rachel E
RE
Nelson
Richard W
RW
Hornof
William J
WJ
Feldman
Edward C
EC
D000279:Administration, Cutaneous; D000818:Animals; D002118:Calcium / Q000097:blood; D002371:Cat Diseases / Q000000981:diagnostic imaging / Q000628:therapy*; D017115:Catheter Ablation / Q000662:veterinary*; D002415:Cats; D005260:Female; D006358:Hot Temperature; D006980:Hyperthyroidism / Q000000981:diagnostic imaging / Q000628:therapy / Q000662:veterinary*; D008297:Male; D011446:Prospective Studies; D012008:Recurrence; D012449:Safety; D016606:Thyroid Nodule / Q000000981:diagnostic imaging / Q000473:pathology / Q000662:veterinary; D013974:Thyroxine / Q000097:blood; D016896:Treatment Outcome; D014463:Ultrasonography
D013974:Thyroxine; D002118:Calcium