J Am Anim Hosp Assoc, 1990. 26(4): p.433-437.
-Retrospective study of 48 hyperthyroid cats that underwent thyroidectomy over a 10 year period.
PREDISPOSITIONS. Ages ranged from 6-19 years [mean = 12 years, median = 13 years]. There were 27 males and 21 females. Breeds included DSH [34/48], DLH [11/48], Siamese [2/48], and Persian [1/48].
DIAGNOSIS included follicular hyperplasia [49/78], adenomas [19/78], adenocarcinomas [3/78], atrophy [3/78], and mixed adenoma and hyperplasia [1/78].
TREATMENT consisted of thyroidectomy. Intracapsular dissection [34/48–bilateral in 26/34 and unilateral in 8/34], extracapsular dissection [11/48–bilateral in 1/11 and unilateral in 10/11], or unilateral intracapsular dissection and contralateral extracapsular dissection [3/48] were done.
POSTOPERATIVE COMPLICATIONS included hypocalcemia [7/48] which lasted 1-31 days [mean = 8.5 days, median = 4 days] with 4/7 treated for hypocalcemia [bilateral thyroidectomy in 4/4]; severe hemorrhage [4/48–1/4 died]; dehiscence [1/48]; and cardiopulmonary arrest and death during recovery [1/48].
OUTCOME[follow up available in 40/48]
RECURRENCE OF HYPERTHYROIDISM occurred in 4/40 from 13.5-36 mos postop [mean = 23 mos, median = 22 mos]. The original surgical techniques used in these cats included unilateral resection [2/4–extracapsular in 1/2 and intracapsular in 1/2] or bilateral resection [2/4–extracapsular in 1/2 and intracapsular in 1/2]. Multiple recurrences were seen in 2/4. All 4 had ectopic thyroid tissue. Regrowth of abnormal tissue at the site of the originally affected gland was found in 3/4. Repeat surgery was done in 3/4 with further recurrence in 2/3. The other cat was successfully managed on methimazole.
SURVIVAL TIMES of the 40 cats [follow up ranged from 1 day to 74 mos, mean=19 mos, median=12 mos] : of the 21/40 that died or were euthanized, survival times ranged from 1 day to 48 mos [mean = 16 mos, median = 8 mos]. The remaining 19/40 are still alive at follow up of 5-56 mos [mean = 21 mos, median = 15 mos].