Objective—To characterize the dynamics of calcitonin secretion in response to experimentally induced hypercalcemia in cats. Animals—13 healthy adult European Shorthair cats.Procedures—For each cat, the calcitonin response to hypercalcemia (defined as an increase in ionized calcium concentration > 0.3mM) was investigated by infusing calcium chloride solution and measuring circulating calcitonin concentrations before infusion (baseline) and at various ionized calcium concentrations. Calcitonin expression in the thyroid glands of 10 of the cats was investigated by immunohistochemical analysis. Results—Preinfusion baseline plasma calcitonin concentrations were very low in many cats, sometimes less than the limit of detection of the assay. Cats had a heterogeneous calcitonin response to hypercalcemia. Calcitonin concentrations only increased in response to hypercalcemia in 6 of 13 cats; in those cats, the increase in calcitonin concentration was quite variable. In cats that responded to hypercalcemia, calcitonin concentration increased from 1.3 ± 0.3 pg/mL at baseline ionized calcium concentration to a maximum of 21.2 ± 8.4 pg/mL at an ionized calcium concentration of 1.60mM. Cats that did not respond to hypercalcemia had a flat calcitonin-to-ionized calcium concentration curve that was not modified by changes in ionized calcium concentration. A significant strong correlation (r = 0.813) was found between the number of calcitonin-positive cells in the thyroid gland and plasma calcitonin concentrations during hypercalcemia. Conclusions and Clinical Relevance—Healthy cats had very low baseline plasma calcitonin concentrations. A heterogeneous increase in plasma calcitonin concentration in response to hypercalcemia, which correlated with the expression of calcitonin-producing cells in the thyroid, was identified in cats.

An adult beagle dog was presented with a cervical mass detected by palpation and computed tomography. Fine needle aspirates revealed numerous epithelial cells with plasmacytoid appearance and frequent naked nuclei. Histologically, the mass consists of multiple packets of neoplastic cells and extensive areas of necrosis and fibrosis. Neoplastic cells were also found in submandibular lymph nodes. Immunohistochemistry showed that neoplastic cells were positive for calcitonin and negative for thyroglobulin. Based on these findings, the cervical mass was diagnosed as thyroid C-cell carcinoma. Almost one year after the surgical excision, the dog remains healthy without any symptom of recurrence or metastasis.

Objective-To determine gene expression of selected molecular markers (tumor necrosis factor TNF-alpha, interleukin IL-1beta, IL-6, IL-8, IL-10, procalcitonin PCT, and transforming growth factor TGF-beta) in the blood of healthy and sick foals. Animals-28 sick foals without sepsis, 21 foals with sepsis, and 21 healthy foals. Procedures-Total RNA was extracted from blood samples and converted into complementary DNA (cDNA). Gene expression was measured for the molecular markers by use of real-time PCR assay, and final quantitation was performed with the comparative threshold cycle method. Results-Samples from all foals yielded transcription for all markers. Expression of TNF-alpha and TGF-beta was significantly lower and that of IL-8 significantly greater in the sick-nonseptic and septic groups, compared with the healthy group. No significant difference in expression of IL-1beta, IL-6, and PCT was found between the healthy group and the 2 sick groups. Expression of IL-10 was significantly greater in nonsurvivors, compared with survivors. Conclusions and Clinical Relevance-The cytokine profile in foals with sepsis may suggest an immunosuppressive state. Expression of IL-10 may be a marker for identification of foals with a guarded prognosis.

Distribution of pulmonary nerves immunoreactive for either substance P or calcitonin gene-related peptide was determined, using immunohistochemical methods on healthy lungs from adult equids. The overall patterns of distribution of substance P and calcitonin gene-related peptide-like immunoreactivity were similar. Distribution of immunoreactive nerves was not uniform throughout the lungs; nerve fibers immunoreactive for these peptides were more frequently observed near the hilus of the lung than in the caudal lobes or in the periphery of the lung. Nerve fibers mununoreactive for substance P or calcitonin gene-related peptide were most abundant in the propria of the trachea and large airways, particularly within and directly below the airway epithelium, they were also frequently associated with bronchial and pulmonary vessels. Presence of nerve fibers immunoreactive for substance P and calcitonin gene-related peptide in peribronchial neural ganglia indicated that these sensory nerves may modulate parasympathetic regulation of pulmonary function. Nerve fibers immunoreactive for substance P and calcitonin gene-related peptide were, therefore, well placed to detect inhaled agents and to contribute to the pulmonary response to irritants and pathogens.

Selective parathyroidectomy (PTX) is preferred to thyroparathyroidectomy (TPTX) when specific effects of parathyroid hormone depletion are being studied. However, because of the anatomic proximity of thyroid and parathyroid glands, TPTX often is performed, leaving animals depleted of thyroxine (T4) and calcitonin as well as parathyroid hormone (PTH). In the present study, six normal dogs had parathyroid tissue and about seven-eighths of thyroid tissue removed. This quantity of thyroid tissue was inadequate to maintain normal serum T4 concentrations, despite allowance of 168 days for thyroid recovery. Five of six dogs with reduced renal mass had successful selective PTX and normal serum T4 concentrations at 28 days, when one-half or more of thyroid tissue was spared. We conclude that with attention to the surgical technique, selective PTX can be achieved in a high percentage of dogs and sufficient thyroid tissue spared to maintain euthyroidism.