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1.
The molecular structure of cardiac troponin I (cTnI) is highly conserved across mammalian species and assays developed for its measurement in human patients have been validated in a number of veterinary species. A raised concentration of circulating cTnI is a sensitive and specific marker of cardiac myocyte injury. Raised levels have been documented in a variety of cardiac diseases in both human and veterinary patients. This study compared serum cTnI concentrations between 16 cats diagnosed with hypertrophic cardiomyopathy (HCM) using echocardiography and 18 control cats. The results show that cats with HCM have significantly higher concentration of serum cTnI (median 0.95 ng/ml, range 0.2-4.1 ng/ml) than control cats (median <0.2 ng/ml, range <0.2-0.25 ng/ml) [P<0.0001]. Furthermore in cats with cardiomyopathy a weak correlation was found between the thickness of the left ventricular freewall in diastole measured by ultrasound and serum cTnI concentration (r(2)=0.28;P=0.036). These results suggest that measurement of serum cTnI concentration may enable cats with cardiomyopathy to be distinguished from normal cats using the assay described here.  相似文献   

2.
Although feline hyperthyroidism has become a commonly diagnosed disorder of older cats, the underlying etiology remains unknown. Pathological findings of adenomatous hyperplasia involving both thyroid lobes in most hyperthyroid cats suggests the possibility that feline hyperthyroidism may be similar to human Graves' disease, which results from high circulating levels of thyroid stimulating immunoglobulins (TSIs). To exclude high circulating levels of TSIs as the cause of feline hyperthyroidism, we measured intracellular concentrations of cyclic adenosine monophosphate (cAMP) in functioning rat thyroid cells (FRTL-5) incubated with IgG extracted from hyperthyroid cat serum. Since TSIs stimulate thyroid hormone secretion through activation of cAMP, their presence can be evidenced in vitro by generation of high cAMP concentrations in cultured thyroid cells. No significant difference was found in intracellular cAMP concentrations in FRTL-5 cells incubated with IgG from normal versus hyperthyroid cats. In contrast, IgG from a human patient with Graves' disease caused substantially more cAMP generation than either normal human IgG or IgG from the cats of this study. These results indicate that feline hyperthyroidism does not result from high circulating concentrations of TSI and, in that respect, is not analogous to Graves' disease.  相似文献   

3.
Echocardiographic findings in 103 cats with hyperthyroidism   总被引：1，自引：0，他引：1  
Using M-mode echocardiography, cardiac abnormalities were studied in 103 cats with untreated hyperthyroidism. In addition, follow-up echocardiography was performed on 24 of these cats to assess the long-term (4 to 21 months) effect of treatment (thyroidectomy or radioiodine) on thyrotoxic cardiac disease. The most common echocardiographic abnormality in the 103 untreated hyperthyroid cats was hypertrophy of the left ventricular caudal wall (71.9%). Hypertrophy of the interventricular septum also was documented in 39.8% of the 103 cats. Other abnormalities included high values for left atrial diameter (70.0%), aortic root diameter (18.5%), and left ventricular diameter at end diastole (45.6%). In some of these cats, indices of contractility were enhanced; in 21.4% and 14.6% of the cats, values for shortening fraction and velocity of circumferential fiber shortening, respectively, were greater than those values measured in clinically normal cats. After treatment of the hyperthyroidism, left ventricular hypertrophy resolved or improved in many of the cats, as indicated by decreases in left ventricular caudal wall and interventricular septum thicknesses. Hyperdynamic wall motion resolved in all cats after treatment, as evidenced by consistent decreases in shortening fraction and velocity of circumferential fiber shortening. Despite these improvements, some cats had one or more persistently abnormal echocardiographic values after treatment. These results suggested that in cats, hyperthyroidism commonly is associated with largely reversible cardiomyopathy. In those cats in which cardiomyopathy persists or worsens after treatment, underlying primary cardiomyopathy or thyroid hormone-induced cardiac structural damage may exist.  相似文献   

4.
Excessive or deficient intake of iodine may play a role in the development of goitre and hyperthyroidism in cats. Previous investigations have shown that the serum free thyroxine level of cats is affected by brief administration of food high or low in iodine content. We have now measured serum free thyroxine levels in groups of cats fed relatively high or low iodine diets for much longer periods (5 months). In contrast to our earlier findings, the chronic ingestion of relatively high or low iodine diets did not lead to statistically significant differences in serum free thyroxine levels. The results of the present investigations show that the cat is able to maintain normal levels of thyroid hormone despite prolonged high or low iodine diets. It may be that the adaptive mechanisms that are called into play during chronic high or low iodine intake lead to thyroid disease, particularly in certain predisposed individuals.  相似文献   

5.
The purpose of this study was to investigate the effects of methimazole on renal function in cats with hyperthyroidism. Twelve cats with naturally occurring hyperthyroidism and 10 clinically normal (i.e., control) cats were included in this study. All cats initially were evaluated with a history, physical examination, complete blood count, serum biochemistry profile, basal serum total thyroxine concentration, complete urinalysis, and urine bacterial culture. Glomerular filtration rate (GFR) was estimated by a plasma iohexol clearance (PIC) test. After initial evaluation, hyperthyroid cats were treated with methimazole until euthyroidism was achieved. Both groups of cats were then reevaluated by repeating the initial tests four to six weeks later. The mean (+/-standard deviation) pretreatment estimated GFR for the hyperthyroid cats was significantly higher (3.83+/-1.82 ml/kg per min) than that of the control cats (1.83+/-0.56 ml/kg per min). Control of the hyperthyroidism resulted in a significantly decreased mean GFR of 2.02+/-0.81 ml/kg per minute when compared to pretreatment values. In the hyperthyroid group, the mean increases in serum urea nitrogen (SUN) and creatinine concentrations and the mean decrease in the urine specific gravity after treatment were not statistically significant when compared to pretreatment values. Two of the 12 hyperthyroid cats developed abnormally high serum creatinine concentrations following treatment. These results provide evidence that cats with hyperthyroidism have increased GFR compared to normal cats, and that treatment of feline hyperthyroidism with methimazole results in decreased GFR.  相似文献   

6.
Serum Thyroid Hormone Concentrations Fluctuate in Cats with Hyperthyroidism   总被引：3，自引：0，他引：3  
We measured serum thyroxine (T4) and 3,3',5-triiodothyronine (T3) concentrations in hyperthyroid cats (hourly for 10 hours in 14 cats, and daily for 15 days in seven cats) to assess fluctuation in thyroid hormone levels. Over the 10-hour study period the coefficient of variation (CV) for serum T4 and T3 concentrations ranged from 6.4-22.6% (mean = 12.0 +/- 4.8%) and from 9.6-33.1% (mean = 17.5 +/- 6.3%), respectively. During the 15-day study period, CV for serum T4 ranged from 6.6-34.8% (mean = 18.4 +/- 9.3%), while CV for serum T3 ranged from 7.8-31.0% (mean = 20.1 +/- 8.6%). These CV values were significantly higher than the expected intra-assay CVs (T4 assay, 5.1%; T3 assay, 7.7%). In addition, some of the cats with mild hyperthyroidism showed one or more normal serum T4 and T3 values during the course of the respective study periods. There was no specific time during the 10-hour study period at which the cats consistently showed peak serum T4 or T3 concentrations. These results suggest that serum thyroid hormone concentrations are subject to a degree of fluctuation that exceeds the usual assay variation, and that cats with mild hyperthyroidism can, at a given time, exhibit normal serum T4 and T3 values. Therefore, a diagnosis of feline hyperthyroidism should not be excluded on the basis of the finding of a single normal serum T4 or T3 value in a cat with clinical signs and physical examination findings consistent with the disease.  相似文献   

7.
OBJECTIVE: To determine the efficacy and safety of percutaneous ethanol injection (PEI) for the treatment of hyperthyroidism caused by bilateral hyperplastic thyroid nodules in cats. DESIGN; Prospective study. ANIMALS: 7 cats. PROCEDURE: Hyperthyroidism was diagnosed on the basis of clinical signs and increased serum total thyroxine (TT4) concentrations. The presence of 2 cervical thyroid nodules was confirmed by use of ultrasonography and technetium Tc 99m albumin thyroid scans. After the death of 1 cat that received PEI in both thyroid nodules at the same time, the protocol was changed to injecting ethanol into 1 nodule at a time, with at least 1 month between injections. Clinical signs, serum TT4 concentrations, serum ionized calcium concentrations, laryngeal function, findings on ultrasonographic examinations of the ventral cervical region, and results of thyroid scans were monitored. RESULTS: Serum TT4 concentrations transiently decreased in all 6 cats (into the reference range in 5 of 6 cats) within 4 days of the first staged ethanol injection. Each subsequent injection resulted in a transient decrease in serum TT4 concentration. The longest period of euthyroidism was 27 weeks. Adverse effects included Horner's syndrome, dysphonia, and laryngeal paralysis. One cat died of unrelated causes. One cat underwent bilateral thyroidectomy, 2 cats were treated with methimazole, and 2 cats that had increased serum TT4 concentrations were not treated further, because they remained clinically normal. CONCLUSIONS AND CLINICAL RELEVANCE: Percutaneous ethanol ablation of bilateral thyroid nodules as a treatment for cats with hyperthyroidism is not recommended. This treatment is not as efficacious as the medical and surgical treatments presently used.  相似文献   

8.
Nineteen cats with abnormally high serum T4 concentrations underwent thyroid scintigraphy using technetium-99m pertechnetate (99mTcO4) before and after 36 +/- 6 days of methimazole administration (approximately 2.5mg PO q 12 h). Thyroid-to-salivary gland ratios (T:S ratios) and percentage thyroidal uptake of injected radioactivity at 20 and 60min after injection of 99mTcO4 were compared before and after methimazole treatment. Serum thyroid stimulating hormone (TSH) concentration was measured before and after methimazole treatment. Quantitatively, there was a positive association between the thyroid uptake of 99mTcO4 and the serum T4 before treatment (r = 0.74-0.83). TSH suppression was present when cats were first evaluated for hyperthyroidism. Methimazole treatment did not relieve TSH suppression in 17 cats. Two cats with unilateral thyroid uptake developed bilateral, asymmetric thyroid uptake of 99mTcO4 after treatment and had the greatest increase in TSH concentration after treatment. Quantitatively, thyroid scintigraphy did not significantly change after methimazole treatment (P>0.1). Evaluation of serum TSH concentration may be helpful in identifying methimazole-induced changes in the scintigraphic features of hyperthyroidism in mildly hyperthyroid cats.  相似文献   

9.
Basal serum thyroxine (T4) concentration and the thyrotropin-releasing hormone (TRH) stimulation test were used to assess thyroid function in 36 critically ill cats examined between July 1996 and October 1998. Of the 36 cats. hyperthyroidism (as underlying or complicating disease) was suspected in 22 based on clinical signs, palpable thyroid nodules, and abnormal thyroid gland histology (study group). Hyperthyroidism was not suspected in the remaining 14 cats, which served as the control group. Based on serum T4 concentrations, suppression of thyroid function was documented in 14 (64%) cats of the study group and in 10 (71%) cats of the control group. The TRH stimulation test revealed an increase in serum T4 of less than 50% of the baseline concentration in 18 (82%) cats of the study group, and in 6 (43%) cats of the control group. In conclusion, based on the results of serum T4 determinations and the TRH stimulation tests, it was not possible to differentiate between cats with clinical and histologic evidence of thyroid dysfunction (hyperthyroidism) and cats with severe nonthyroidal illnesses.  相似文献   

10.
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.  相似文献   

11.
Two-dimensional echocardiography (2DE) and M-mode echocardiography were used to image the heart of 13 clinically healthy cats. Seven awake cats and six cats tranquilized with a combination of acetylpromazine and ketamine were studied. Six cats were studied by 2DE on 3 consecutive days to assess repeatability of the study. Long-axis and short-axis echocardiographic tomograms were obtained from the right parasternal location, and these images were used to determine internal cardiac dimensions, ventricular and septal wall thicknesses, repeatability of the study, and interobserver variability. Some but not all parameters were significantly (P < 0.05) related to body weight. Significant correlations (P <0.05) were found between measurements obtained by long-axis and by short-axis image planes. Comparison of parameters measured by 2DE and M-mode echocardiography demonstrated minimal differences between mean values. Repeatability of the 2DE study was good with 14 of 16 parameters having a mean percent error less than 10%. Interobserver variability was acceptable for some but not all parameters. The study indicates that repeatable 2DE tomograms can be obtained in the cat and that quantitation of cardiac anatomy is possible with this imaging technique.  相似文献   

12.
Background: Methimazole suppresses thyroid hormone synthesis and is commonly used to treat feline hyperthyroidism. The degree of variation in thyroid hormone concentrations 24 hours after administration of methimazole and optimal time for blood sampling to monitor therapeutic efficacy have not been determined.
Objective: To assess thyroid hormone concentration variation in serum of normal and hyperthyroid cats after administration of methimazole.
Animals: Four healthy cats and 889 retrospectively acquired feline thyroid hormone profiles.
Methods: Crossover and retrospective studies . In the crossover study, healthy cats were treated with increasing doses of oral methimazole until steady state of thyroid suppression was achieved. Thyroid hormones and thyroid stimulating hormone (TSH) were serially and randomly monitored after methimazole. Paired t -tests and a 3-factor analysis of variance were used to determine differences between thyroid hormone concentrations in treated and untreated cats in the crossover study. Thyroid profiles from methimazole-treated hyperthyroid cats were retrieved from the Diagnostic Center for Population and Animal Health database and reviewed. Linear regression analysis evaluated relationships of dosage (mg/kg), dosing interval (q24h versus q12h), and time after methimazole to all thyroid hormone concentrations.
Results: All serum concentrations of thyroid hormones were significantly suppressed and TSH was significantly increased for 24 hours after administration of oral methimazole in healthy cats ( P < .005). In hyperthyroid cats, there were no significant relationships between thyroid hormone concentrations and time postpill or dosing interval.
Conclusions: Timing of blood sampling after oral methimazole administration does not appear to be a significant factor when assessing response to methimazole treatment.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
OBJECTIVE: To determine efficacy and safety of percutaneous radiofrequency heat ablation for treatment of hyperthyroidism in cats. DESIGN: Prospective study. ANIMALS: 9 cats. PROCEDURE: Hyperthyroidism was diagnosed via clinical signs and high serum total (TT4) and free thyroxine (fT4) concentrations. One or 2 hyperfunctional cervical thyroid nodules were detected by use of scintigraphy and ultrasonography. If cats had 1 abnormal thyroid lobe, heat ablation was performed on that lobe; if cats had 2 abnormal lobes, heat ablation was applied to the larger lobe. Overall, heat ablation was performed 14 times in the 9 cats. Clinical signs and serum TT4, fT4, and calcium concentrations were monitored daily for 2 days after the procedure, weekly for the first month, and then monthly. Laryngeal function was evaluated and cervical ultrasonography and thyroid scintigraphy were also performed. Monitoring continued for as long as 9 months after heat ablation if a cat became euthyroid or until an owner chose an alternative treatment because of recurrence of hyperthyroidism. RESULTS: Serum TT4 and fT4 concentrations transiently decreased after all 14 heat ablation procedures (< or = reference range after 10 of 14 treatments) within 2 days after the procedure. Cats were euthyroid for 0 to 18 months (mean, 4 months). Hyperthyroidism recurred in all cats. Adverse effects included transient Horner's syndrome (2 cats) and laryngeal paralysis without clinical signs (1 cat). CONCLUSIONS AND CLINICAL RELEVANCE: Percutaneous heat ablation as a treatment for hyperthyroidism in cats is effective transiently but not permanently.  相似文献   

16.
OBJECTIVE: To determine whether plasma cardiac troponin I (cTnI) concentrations can be used to discriminate cardiac from noncardiac causes of dyspnea in cats. DESIGN: Prospective, multicenter study. ANIMALS: Client-owned cats with dyspnea attributable to congestive heart failure (D-CHF; n=31) or to noncardiac causes (D-NCC; n=12). PROCEDURES: For each cat, plasma cTnI concentration was analyzed by use of a solid-phase radial partition immunoassay; values in cats with D-CHF and D-NCC were compared. A receiver operating characteristic curve was analyzed to determine the accuracy of plasma cTnI concentration for diagnosis of D-CHF. RESULTS: Median plasma concentration of cTnI in cats with D-CHF (1.59 ng/mL; range, 0.20 to 30.24 ng/mL) was significantly higher than in cats with D-NCC (0.165 ng/mL; range, 0.01 to 1.42 ng/mL). With regard to the accuracy of plasma cTnI concentration for diagnosis of D-CHF, the area under the receiver operating characteristic curve was 0.84. At plasma concentrations > or = 0.2 ng/mL, cTnI had 100% sensitivity but only 58% specificity for identification of CHF as the cause of dyspnea. At plasma concentrations > or = 1.43 ng/mL, cTnI had 100% specificity and 58% sensitivity for identification of CHF as the cause of dyspnea. CONCLUSIONS AND CLINICAL RELEVANCE: On the basis of the derived diagnostic limits, CHF as the cause of dyspnea could be ruled in or ruled out without additional diagnostic testing in > 50% of the study cats. Measurement of plasma cTnI concentration may be clinically useful for differentiation of cardiac from noncardiac causes of dyspnea in cats. (J Am Vet  相似文献   

17.
The historical and clinical features and the haematological and biochemical changes in 126 cats with hyperthyroidism are described; 125 of the cats were domestic short- or longhaired, and one was a chinchilla. There were 62 males and 64 females with a mean age of 13.0 years. The duration of signs ranged from two days to two years with a mean of 5.4 months. The historical and clinical features were weight loss, polyphagia, polyuria/polydipsia, tachycardia, hyperactivity, diarrhoea, respiratory abnormalities, other cardiac abnormalities, skin lesions, vomiting, moderately raised temperature, decreased activity, decreased appetite, congestive cardiac failure, haematuria and intermittently decreased appetite. Goitre was palpable in 123 cats. The serum total thyroxine concentrations of the cats were more than three standard deviations above the mean of the reference range. Serum total tri-iodothyronine concentrations ranged from 0.78 to 14.96 nmol/litre and were within the reference range in 11 of the cats. Mild hyperthyroidism was a much commoner cause of high normal or marginally above normal thyroid hormone concentrations than severe, concurrent, non-thyroidal illness. Other common biochemical changes were increased of serum alanine aminotransferase, urea, aspartate aminotransferase, alkaline phosphatase and lactate dehydrogenase. There were minimal changes in the red cell parameters. Leucocyte changes showed two trends: a mature neutrophilia, either with or without an accompanying leucocytosis often in association with a lymphopenia, or an eosinophilia, either with or without a lymphocytosis.  相似文献   

18.
Hyperthyroidism was diagnosed in 4 cats with congestive heart failure. Dyspnea and anorexia were observed in 3 of the 4 cats. In each cat, a holosystolic left and/or right apical heart murmur was auscultated. In 3 cats, a prominent extra heart sound (gallop rhythm) was auscultated. All cats had a palpably large thyroid lobe(s) and weight loss. The laboratory and ECG changes were similar to those reported for feline hyperthyroidism. Moderate-to-severe pleural effusion and cardiomegaly were detected via radiography in all cats. Some cats had radiographic signs of pulmonary venous engorgement and pulmonary edema. Echocardiography revealed cardiac dilatation and low left ventricular shortening fraction (wall motion) in all cats. Three cats responded initially to cardiac drugs and propylthiouracil or thyroidectomy. One of these died later, presumably from an adverse reaction to propylthiouracil, and the others died from recurrent congestive heart failure (1) or postoperative cardiac arrest (1). One cat did not respond to treatment, and died 2 days after diagnosis.  相似文献   

19.
An 8-month-old, male domestic shorthaired cat presented for chronic weight loss, intermittent dyspnea, chronic diarrhea, hyperactivity, and weakness. The cat had a palpable thyroid nodule and increased serum total thyroxine and 3,5,3' triiodothyronine levels. The cat was diagnosed with hyperthyroidism, and a unilateral thyroidectomy was performed followed by radioactive iodine at a later date. The clinical signs resolved following radioactive iodine, and the cat subsequently developed clinical hypothyroidism.  相似文献   

20.
This study evaluated the effects of thyroxine on renal function in the cat. Baseline serum thyroxine (T4) concentrations, clinicopathologic data (complete blood count [CBC], serum chemistry panel, urinalysis), and nuclear medicine determinations of glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and effective renal blood flow (ERBF) were measured in 10 normal adult cats. Cats were then injected with thyroxine (T4) (50 micrograms/kg SQ) daily for 30 d to induce hyperthyroidism. Clinicopathologic and nuclear medicine studies were repeated at 30 d. Cats injected with thyroxine had significant increases in T4, GFR, and ERBF and significant declines in serum creatinine and blood urea nitrogen (BUN) values. Administration of high doses of exogenous thyroxine to cats results in significant stimulation of renal function.  相似文献   

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