Clinical techniques in small animal practice最新文献

Dogs and cats of our society have outgrown their status as merely pets and are now considered our close companions and even family members. This shift in their roles has led to pet owners seeking improved preventative medicine for their four-legged friends. Subsequently, dogs and cats are living longer lives than ever before and developing more old-age-related diseases. One of the most devastating diseases of older animals is cancer. Once a veterinarian has detected cancer in a pet, pet owners seek advice on their next course of action. This article is intended to provide concise information regarding the diagnosis and treatment of intranasal tumors of the dog and cat. This article outlines the forms of nasal tumors that are the most common, the recommended imaging and biopsy techniques to diagnose the tumor, and the most appropriate treatments of them.

Diseases of the nasal cavity and sinuses can be frustrating problems for owners and veterinarians alike. Initial physical examination and routine blood work are often unrewarding in directing the clinician at a diagnosis. Diagnostic imaging can help characterize the disease process and direct treatment or further diagnostics. Radiographs of the skull are an excellent first-line diagnostic step in the analysis of nasal disease. The following article reviews basic techniques, positioning, and interpretation of radiographs of the nasal cavity and paranasal sinuses.

Chronic inflammatory rhinitis is commonly found in dogs with chronic nasal disease and is characterized by lymphoplasmacytic infiltrates in the nasal mucosa in the absence of an obvious etiologic process. The pathogenesis of lymphoplasmacytic rhinitis remains unknown. Animals respond poorly to antibiotics, oral glucocorticoids, and antihistamines, making primary infectious, immune-mediated, or allergic etiologies unlikely. Aberrant immune response to inhaled organisms or allergens may induce inflammation in some animals. Common clinical signs include nasal discharge, sneezing, coughing, epistaxis, and stertor. Diagnosis is made by performing a thorough history, physical examination, radiography or advanced imaging (via computed tomography or magnetic resonance imaging), rhinoscopy, and nasal mucosal biopsy to rule out primary etiologies of nasal discharge. Treatment strategies have included various antibiotics, antihistamines, oral and inhalant steroids, nonsteroidal antiinflammatories, and antifungal medications. Some dogs may respond partially to doxycycline or azithromycin, although it is unclear whether response is related to antimicrobial or antiinflammatory properties of these drugs. Hydration of the nasal cavity through nasal drops or aerosols may limit nasal discharge, and some animals may improve with inhalant (but rarely oral) glucocorticoids.

Radioiodine is considered the treatment of choice for hyperthyroidism, but in some situations, methimazole therapy is preferred, such as in cats with pre-existing renal insufficiency. Methimazole blocks thyroid hormone synthesis, and controls hyperthyroidism in more than 90% of cats that tolerate the drug. Unfavorable outcomes are usually due to side effects such as gastrointestinal (GI) upset, facial excoriation, thrombocytopenia, neutropenia, or liver enzyme elevations; warfarin-like coagulopathy or myasthenia gravis have been reported but are rare. Because restoration of euthyroidism can lead to a drop in glomerular filtration rate, all cats treated with methimazole should be monitored with BUN and creatinine, in addition to serum T4, complete blood count, and liver enzymes. Transdermal methimazole is associated with fewer GI side effects, and can be used in cats with simple vomiting or inappetance from oral methimazole. Hypertension may not resolve immediately when serum T4 is normalized, and moderate to severe hypertension should be treated concurrently with atenolol, amlodipine, or an ACE inhibitor. Alternatives to methimazole include carbimazole, propylthiouracil, or iodinated contrast agents.

Thyroidectomy in cats is most commonly indicated to treat hyperthyroidism because of adenomatous hyperplasia of the thyroid glands. Preoperative stabilization of the hyperthyroid cat with antithyroid drugs is preferred to minimize anesthetic and surgical complications. Multiple surgical techniques for thyroidectomy have been reported, and results of surgery and complications differ between techniques. The extracapsular technique offers the most complete removal of abnormal thyroid tissue, while still being associated with a low incidence of postoperative hypoparathyroidism. Important postoperative considerations are to carefully monitor serum calcium concentrations and treat hypocalcemia if necessary, and to monitor the cat for evidence of relapse of hyperthyroidism.

Radioactive iodine provides a simple, effective, and safe treatment for cats with hyperthyroidism and is regarded by most authorities to be the treatment of choice. It is a particularly useful treatment for cats with bilateral thyroid involvement (found in approximately 70% of cats), cats with ectopic (intrathoracic) thyroid tissue, and the rare patient with thyroid carcinoma. Treatment with radioiodine avoids the inconvenience of daily, oral administration of an antithyroid drug, as well as the side effects commonly associated with these drugs. Use of radioiodine also avoids the risks and perioperative complications associated with anesthesia and surgical thyroidectomy. Radioiodine treatment involves a single, nonstressful procedure that is without associated morbidity or mortality. A single treatment restores euthyroidism in most cats with hyperthyroidism. Whereas the therapy is simple and relatively stress-free for cats, it does require special licensing and hospitalization facilities, nuclear medicine equipment, and extensive compliance with local and state radiation safety laws.

The diagnosis of hyperthyroidism, one of the most common disorders affecting elderly cats, is usually straightforward and considered routine by most practitioners. Nowadays, however, most cats suffering from hyperthyroidism tend to be diagnosed earlier and at a milder stage of the disease than those cats diagnosed 10 to 25 years ago. There are, in fact, a growing number of cats with clinical signs of hyperthyroidism and palpably large thyroid glands whose baseline serum total thyroid hormone concentrations are within the normal or borderline range, making diagnosis problematic. This paper reviews the available tests used to confirm a diagnosis of hyperthyroidism in cats and discusses their overall usefulness.

Thyroid scintigraphy is a nuclear medicine procedure that produces a visual display of functional thyroid tissue based on the selective uptake of various radionuclides by thyroid tissue. Thyroid scintigraphy provides valuable information regarding both thyroid anatomy and physiology and can play an integral role in the diagnosis and management of cats with hyperthyroidism. Thyroid scintigraphy allows the direct visualization of the functional adenomatous thyroid tissue responsible for the development of hyperthyroidism. For this reason, thyroid scintigraphy will allow the diagnosis of hyperthyroidism before laboratory tests are consistently abnormal. Thyroid scintigraphy can also exclude a diagnosis of hyperthyroidism in cats with thyroid hormone elevations of nonthyroidal origin. Thyroid scintigraphy provides an additional method for determining the relative severity of thyroid disease that is less affected by the presence of concurrent nonthyroidal illness than laboratory evaluations. When treating hyperthyroid cats with radioiodine, the lowest effective dose should be administered. In an effort to administer the lowest radioiodine dose possible, the volume of adenomatous thyroid tissue present in the individual hyperthyroid cat should be considered. Thyroid scintigraphy provides an excellent method for evaluating the size of hyperfunctional thyroid tissue that is not limited by the presence of ectopic or intrathoracic thyroid tissue. Thyroid scintigraphy also provides valuable information in the diagnosis and evaluation of hyperthyroid cats with thyroid carcinoma.