Ultrasonographic Evaluation of the Thyroid Gland in Healthy, Hypothyroid, and Euthyroid Golden Retrievers with Nonthyroidal Illness

Abstract

Ultrasound evaluation of the thyroid gland was performed in healthy, hypothyroid, and euthyroid Golden Retriever dogs with nonthyroidal illness (NTI) to determine the diagnostic usefulness of ultrasound for differentiating between euthyroid and hypothyroid dogs. Thirty-six healthy, 11 hypothyroid, and 35 euthyroid dogs with NTI were evaluated. Each thyroid lobe was examined ultrasonographically for size, shape, echogenicity, and homogeneity. Thyroid lobe volume was estimated by using the equation for an ellipsoid: /6(length ϫ height ϫ width). No differences were found between healthy dogs and euthyroid dogs with NTI. In the majority of euthyroid dogs, the thyroid lobes were fusiform and triangular in shape in longitudinal and transverse planes, respectively. The thyroid capsule appeared smooth. The thyroid parenchyma had a homogeneous echogenic pattern and usually was hyperechoic or isoechoic compared with the surrounding musculature. Ultrasound findings in hypothyroid dogs were more variable, including a greater frequency of round to oval-shaped thyroid lobes in the transverse imaging plane (P Ͻ .05), hypoechogenicity of the thyroid parenchyma compared with surrounding musculature (P Ͻ .001), and a decrease in the size and volume of the thyroid lobes and total volume of the thyroid gland (P Ͻ .05) compared with euthyroid dogs. Other findings in hypothyroid dogs included an irregular surface to the thyroid capsule, a heterogeneous pattern to the thyroid parenchyma, and differences in the echogenic pattern between the left and right thyroid lobes. Results suggest that determination of thyroid size and volume by ultrasound may be a useful adjunctive test for differentiating between hypothyroid and euthyroid dogs with NTI.

Quantitative Pertechnetate Thyroid Scintigraphy and the Ultrasonographic Appearance of the Thyroid Gland in Clinically Normal Horses

“…95 The sonographic appearance of the thyroid gland has been reported for clinically normal, hypothyroid and euthyroid (dogs with nonthyroidal illness) golden retrievers. 98 Thirty-six normal, 11 hypothyroid and 35 euthyroid dogs were included in the study. A single breed was chosen for investigation to negate possible effects of breed and thyroid gland size as a potential confounding factor when analysing results.…”

“…Results indicate that sonography may be helpful to confirm hypothyroidism in a patient with a thyroid gland volume below the suggested reference interval but would not rule it out if thyroid volume measured within the reference interval. 98 A follow up to the previously described study was performed to compare the sonographic characteristics of the thyroid gland in healthy small, medium and large-breed dogs. 99 The objective was primarily to examine differences in thyroid gland size and volume among different breeds and sizes of dog.…”

“…64,79,107 Ultrasound can also effectively differentiate between euthyroid sick dogs and truly hypothyroid patients. 98,103 There has been limited use of pertechnetate thyroid scintigraphy and ultrasound in the evaluation of the thyroid gland in horses. These modalities have only been used in a nonquantitative fashion to evaluate patients with cervical masses or clinical signs of hyperthyroidism.…”

Spuriously high thyroid hormone concentrations measured by chemiluminescent immunoassay attributable to anti‐iodothyronine antibodies in a dog

“…No abnormalities were detected during physical examinations including palpation of the neck and an electrocardiogram was interpreted as normal. Ultrasonographic examination revealed large (left: 30.3×8.5×10.6 mm; right 28×9.6×10.4 mm) and oval-shaped thyroid glands with a hypoechoic pattern characteristic of thyroiditis (Brömel and others 2005). Hormone measurements repeated within two months using validated CLIAs (Singh and others 1997) revealed very high TSH, high free T4 (FT4), but now TT4 concentrations within the reference interval (see Table 1).…”

Thyroid Ultrasound in Dogs: a Review

“…[46][47][48] One or several of these five reported features may be present simultaneously in the same lobe, and the ultrasound characteristics may differ between the two lobes. [46][47][48] An increasing number of abnormalities detected in the same gland results in a higher sensitivity for diagnosing hypothyroidism. 47,48 Sensitivities of between 94 and 98% have been reported for detecting hypothyroidism using a combination of these five different ultrasound features.…”