Table 1.
Clinical and scintigraphic characteristics of 2096 hyperthyroid cats, divided into five groups based on disease duration
| Time from diagnosis | All cats | Group 1 (⩽1 year) | Group 2 (>1–2 years) | Group 3 (>2–3 years) | Group 4 (>3–4 years) | Group 5 (>4–6.1 years) |
|---|---|---|---|---|---|---|
| Number of cats (%) | 2096 (100.0) | 1773 (84.5) | 169 (8.1) | 88 (4.2) | 35 (1.7) | 31 (1.5) |
| Methimazole (%) | 996 (47.5) | 673 (38.0) | 169 (100.0) | 88 (100.0) | 35 (100.0) | 31 (100.0) |
| Tumor pattern (%) | ||||||
| Unilateral | 665 (31.7) | 599 (33.8) | 39 (23.1) | 18 (20.5) | 6 (17.1) | 3 (9.7) |
| Bilateral | 1317 (62.8) | 1107 (62.4) | 113 (66.9) | 59 (67.0) | 20 (57.2) | 18 (58.0) |
| Multifocal | 81 (3.9) | 48 (2.7) | 13 (7.7) | 8 (9.1) | 5 (14.3) | 7 (22.6) |
| Unclassified | 33 (1.6) | 19 (1.1) | 4 (2.4) | 3 (3.4) | 4 (11.4) | 3 (9.7) |
| Tumor location (%) | ||||||
| Cervical | 2057 (98.1) | 1744 (98.4) | 166 (98.2) | 85 (96.6) | 33 (94.3) | 29 (93.4) |
| Thoracic inlet | 282 (13.5) | 162 (9.1) | 48 (28.4) | 33 (37.5) | 22 (62.9) | 17 (54.8) |
| Thorax | 115 (5.5) | 63 (3.6) | 17 (10.1) | 15 (17.0) | 10 (28.6) | 10 (32.2) |
| Tumor size (%) | ||||||
| Small | 1135 (54.2) | 1101 (62.1) | 26 (15.4) | 7 (8.0) | 1 (2.9) | 0 (0) |
| Medium | 682 (32.5) | 581 (32.8) | 69 (40.8) | 25 (28.4) | 3 (8.6) | 4 (12.9) |
| Large | 230 (11.0) | 82 (4.6) | 64 (37.9) | 47 (53.4) | 21 (60.0) | 16 (51.6) |
| Huge | 49 (2.3) | 9 (0.5) | 10 (5.9) | 9 (10.2) | 10 (28.6) | 11 (35.5) |
| Ectopic (%) | ||||||
| All ectopic locations | 79 (3.8) | 58 (3.3) | 11 (6.5) | 5 (5.7) | 3 (8.6) | 2 (6.4) |
| Sublingual | 8 (0.4) | 7 (0.4) | 1 (0.6) | 0 (0) | 0 (0) | 0 (0) |
| Cervical | 6 (0.3) | 5 (0.3) | 1 (0.6) | 0 (0) | 0 (0) | 0 (0) |
| Mediastinal | 64 (3.1) | 46 (2.6) | 8 (4.7) | 5 (5.7) | 3 (8.6) | 2 (6.4) |
| Both sublingual and mediastinal | 1 (0.05) | 1 (0.1) | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
| Suspected carcinoma (%) | ||||||
| All suspected cases | 35 (1.7) | 9 (0.5) | 6 (3.6) | 6 (6.8) | 6 (17.1) | 8 (25.8) |
| SHIM-RAD subgroup* | 30 (1.4) | 7 (0.4) | 6 (3.6) | 6 (6.8) | 5 (14.3) | 6 (19.3) |
*
SHIM-RAD = subgroup of cats with thyroid tumors that have the following five features: (1) severe hyperthyroidism (serum thyroxine >300 nmol/l); (2) huge tumors; (3) intrathoracic tumor location; (4) multifocal distribution of radionuclide uptake; and (5) refractory to treatment with antithyroid drugs