A riding was presented for evaluation of an enlarging mass in the right cervical region and weight loss of 8 months' duration. The mass had been present for approximately 2 years, but had been increasing in size over the last few months. The owner estimated that the gelding had lost approximately 90 kg. The owner also reported that the gelding had exhibited several episodes of tachypnea associated with anhidrosis over the last 2 weeks and had noted behavioral abnormalities manifested as pacing in the paddock and difficulty when handled.On presentation, the gelding was thin, but was bright and alert. On physical examination, a firm, oblong mass approximately 12 X 9 cm was palpated dorsolateral to the trachea, immediately caudal to the angle of the mandible. The mass was loosely attached and nonpainful. Based on location, the mass was suspected to be a neoplastic thyroid gland. Normal rectal temperature (37.6"C), and respiratory rate (20 breathslminute) were present. However, an intermittent mild tachycardia (48-56 beatdminute) that lasted several minutes and occurred at various times throughout the day was noted. No other abnormalities were noted on clinical examination.Results of CBC and serum biochemistry were within reference range. A homogenous mass that was interspersed with several areas of centrally located hypoechoic foci was observed ultrasonographically, using a 7.5-MHz linear transducer (Ausonics Opus 1, Ausonics, Sydney, Australia). This structure was consistent with the right thyroid gland. Cytologic examination of a fine-needle aspirate of the mass revealed a population of oval to round cells with indistinct cytoplasmic borders, marked anisokaryosis, and prominent nucleoli. Some cells contained darkly pigmented cytoplasmic granules. These changes were consistent with thyroid adenocarcinoma,' but histopathology was recommended for definitive diagnosis (Fig 1).Baseline serum total thyroxine (TT,) concentration measured by a commercially available radioimmunoassay (RIA) kit was 12.4 nmol/L (normal reference range: 8. concentration measured using a commercially available equilibrium dialysis and RIA kit was >126.1 pmol/L (normal reference range: 8.8-30.4 pmol/L; Free T4 by Equilibrium Dialysis, Nichols Institute Diagnostics, San Juan Capistrano, CA). Both assay kits had previously been validated for use in horses.' These results were compatible with a functional thyroid tumor. Treatment options included surgical thyroidectomy or radioactive thyroid ablation using '''1. Adjunct treatment with antithyroid drugs such as methimazole or propylthiouracil also was considered. Surgical resection of the mass was elected due to financial considerations and the limited use of these drugs in horses.The horse was anesthetized and maintained with isoflurane in oxygen, and placed in lateral recumbency with the head and neck extended. A 12-cm skin incision was made caudal to the ramus of the mandible and ventral to the linguofacial vein. Blunt dissection was used to expose the tumorous thyroid gland. The mass was smoot...

Mechanisms to reduce lameness associated with osteoarthritis (OA) are vital to equine health and performance. This study was designed to quantify response to autologous, intra-articular platelet-rich plasma (PRP) in horses with OA. Kinetic gait analysis was performed on 12 horses with unilateral forelimb lameness and OA in the same limb before and after intra-articular anesthesia (IAA). Radiographs and kinetic data were obtained before and 6 and 16 weeks after PRP administration to same joint, 4 weeks after IAA. Statistical evaluations included filtration effect on platelet concentration, relationship between kinetic variable changes after IAA versus PRP in the affected limb, and associations between response to PRP and response to IAA, platelet concentration, and radiographic OA. A positive response to IAA or PRP was defined as ≥5% improvement in peak vertical force, vertical impulse, or breaking impulse of the affected limb. Out of 10 horses that responded to IAA, 3 responded to PRP at both time points and 4 responded at one. Of the two horses that did not respond to IAA, one responded to PRP at both time points. Filtration increased platelet concentration significantly. The relationship between kinetic variable alterations of the affected limb after IAA and PRP was not significant, and response to PRP was not associated with response to IAA, platelet concentration, or radiographic OA. Changes in kinetic variables following IAA in joints with naturally occurring OA provide a custom standard to assess intra-articular therapy. Kinetic gait changes after intra-articular PRP are variable in horses with moderate to severe forelimb OA.

Clenbuterol is a β(2)-adrenergic receptor agonist licensed for veterinary use as a bronchodilator. At doses ≥ 10² μg/kg (4.5 μg/lb), in excess of those normally prescribed, β-adrenergic stimulation by clenbuterol may cause sustained tachycardia, muscle tremors, hyperglycemia, and cardiac and skeletal muscle necrosis. Laminitis, acute renal failure, rhabdomyolysis, and cardiomyopathy were fatal complications associated with clenbuterol overdose in 2 horses in the present report. At the dose administered, propranolol was effective for short-term control of sinus tachycardia, but it did not alleviate all clinical signs in patients in the present report. These cases demonstrated the risks associated with the use of nonprescribed compounded medications for which the ingredients may be unknown.

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