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Objective

To determine whether measuring change in serum thyroid-stimulating hormone (TSH) concentration in response to thyrotropin-releasing hormone (TRH) administration can be used as a test of thyroid function in dogs suspected of having hypothyroidism.

Design

Case-cohort study.

Animals

13 healthy dogs, 20 hypothyroid dogs, and 18 euthyroid dogs with concurrent diseases.

Procedure

Blood samples were collected before and 30 minutes after TRH administration, and serum TSH concentration was measured. The 13 healthy dogs were used to establish a reference range for change in TSH concentration after TRH administration. The remaining 38 dogs were categorized as hypothyroid or euthyroid on the basis of baseline total thyroxine (T4) and TSH concentrations, T4 concentration 4 hours after TRH administration, and clinical response to administration of sodium levothyroxine.

Results

Median baseline TSH concentration was 0.25 ng/ml (range, 0.03 to 0.44 ng/ml) in healthy dogs, 0.93 ng/ml (0.21 to 3.5 ng/ml) in hypothyroid dogs, and 0.21 ng/ml (0.03 to 0.63 ng/ml) in euthyroid dogs with concurrent diseases. Median percentage change in TSH concentration after TRH administration was 207% (range, 25 to 2,200%) in healthy dogs, 24% (-21 to 134%) in hypothyroid dogs, and 167% (69 to 1,800%) in euthyroid dogs with concurrent diseases. Overall accuracy of using the TRH-induced change in TSH concentration to identify hypothyroid dogs was 90%.

Clinical Implications

Although percentage change in TSH concentration in response to TRH administration can be used to differentiate euthyroid from hypothyroid dogs, the test has little advantage over measurement of baseline TSH and total or free T4concentration. (J Am Vet Med Assoc 1998;213:1435-1438)

Free access
in Journal of the American Veterinary Medical Association

Objective

To determine effect of time of sample collection on serum thyrotropin (canine thyroid-stimulating hormone [cTSH]) concentrations in euthyroid and hypothyroid dogs.

Design

Prospective study.

Animals

6 healthy adult euthyroid dogs, 6 adult Beagles with 131iodine-induced hypothyroidism before and during administration of levothyroxine sodium, and 6 adult dogs with naturally developing hypothyroidism.

Procedure

Healthy euthyroid dogs were identified. Hypothyroidism was induced by administration of 131sodium iodide and confirmed by thyroid-stimulating hormone testing. These dogs then received levothyroxine for 30 days. Naturally developing hypothyroidism was diagnosed on the basis of clinical signs, low serum thyroxine (T 4) concentrations, and high cTSH concentrations or abnormal results on a thyrotropin-releasing hormone response test. Samples for measurement of cTSH and T4 concentrations were obtained at 2-hour intervals from 8 AM to 8 pm.

Results

Mean (± SD) serum cTSH concentrations for healthy dogs, dogs with induced hypothyroidism before and during treatment, and dogs with naturally developing hypothyroidism were 0.11 ± 0.08, 3.31 ± 1.30, 0.08 ± 0.07, and 0.55 ± 0.27 ng/ml, respectively. Diurnal variation in cTSH concentrations was not detected. Clinically important random fluctuations in cTSH concentrations were detected for dogs with naturally developing hypothyroidism.

Clinical Implications

Sample collection time does not appear to predictably influence cTSH concentrations; however, dogs with naturally developing hypothyroidism may have random fluctuations in cTSH concentrations. (J Am Vet Med Assoc 1998; 212:1572–1575)

Free access
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Summary

Progesterone was administered im to 6 adult anestrous bitches at a dosage of 2 mg/kg of body weight. Serum progesterone concentrations were measured prior to progesterone administration and for 72 hours thereafter. The serum progesterone concentration time data were analyzed by use of a pharmacokinetics modeling computer program. The mean (± sd) peak serum progesterone concentration (34.3 ± 7.8 ng/ml) was reached at 1.8 ± 0.2 hours after progesterone administration. The mean serum progesterone concentration was 6.9 ± 1.4 ng/ml at 24 hours and 2.0 ± 0.4 ng/ml at 48 hours after progesterone administration. By 72 hours after administration, mean serum progesterone concentration was 0.9 ± 0.2 ng/ml, which was comparable to serum progesterone concentrations prior to injection. The mean half-life of the absorption phase was 0.5 hours (range, 0.3 to 0.7 hours). The mean half-life of elimination was 12.1 hours (range, 9.5 to 13.8 hours). By analysis of the data, it was established that a dosage of 3 mg/kg, when the hormone was given im to dogs once a day, would maintain serum progesterone concentration > 10 ng/ml.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate and compare characteristics of a commercially manufactured protamine zinc insulin (PZI) product and PZI products obtained from various compounding pharmacies.

Design—Evaluation study.

Sample—112 vials of PZI (16 vials of the commercially manufactured product and 8 vials from each of 12 compounding pharmacies) purchased over an 8-month period.

Procedures—Validated methods were used to analyze 2 vials of each product at 4 time points. Appearance, endotoxin concentration, crystal size, insulin concentration in the supernatant, pH, total insulin and zinc concentrations, and species of insulin origin were evaluated.

Results—All 16 vials of commercially manufactured PZI met United States Pharmacopeia (USP) specifications. Of 96 vials of compounded PZI, 1 (1 %) contained a concentration of endotoxin > 32 endotoxin U/mL, 23 (24%) had concentrations of insulin in the supernatant > 1.0 U/mL, and 45 (47%) had pH values < 7.1 or > 7.4; all of these values were outside of specifications. Several vials of compounded PZI (52/96 [54%]) did not meet specifications for zinc concentration (0.06 to 0.1 mg/mL for 40 U of insulin/mL, 0.075 to 0.12 mg/mL for 50 U of insulin/mL, and 0.15 to 0.25 mg/mL for 100 U of insulin/mL), and total insulin concentration in 36 [38%] vials was < 90% of the labeled concentration.

Conclusions and Clinical Relevance—Only 1 of 12 compounded PZI products met all USP specifications in all vials tested. Use of compounded PZI insulin products could potentially lead to serious problems with glycemic control in veterinary patients.

Full access
in Journal of the American Veterinary Medical Association

Objective

To evaluate use of an assay for measuring serum concentration of canine thyroid-stimulating hormone (cTSH) as an aid for diagnosing thyroid disease in a population of dogs suspected of having hypothyroidism.

Design

Case-cohort study.

Animals

62 healthy dogs and 49 dogs with clinical signs consistent with hypothyroidism (16 were hypothyroid and 33 were euthyroid with concurrent disease).

Procedure

Samples from healthy dogs were used to establish a reference range for serum cTSH concentration. The 49 dogs were categorized as hypothyroid or euthyroid with concurrent disease on the basis of clinical signs, results of additional diagnostic and thyroid-stimulating hormone (TSH) response tests, and response to administration of levothyroxine sodium. Function of the thyroid gland was considered normal when serum total thyroxine (T4) concentration 6 hours after TSH administration was > 2.5 µg/dl. Hypothyroidism was diagnosed when serum T4 concentration after TSH administration was ≤ 1.5 µg/dl.

Results

Serum cTSH concentration differed significantly among all 3 groups. Four of 33 (12%) euthyroid dogs had cTSH concentrations that were greater than the reference range, whereas 6 of 16 (38%) hypothyroid dogs had cTSH concentrations within the reference range. Specificity for serum cTSH concentration was 0.88 and sensitivity was 0.63. When interpreted in combination with serum T4 concentration, specificity increased to 1.0.

Clinical Implications

cTSH assay had good specificity for use in the diagnosis of hypothyroidism in dogs. Because this assay had low sensitivity, a diagnosis of hypothyroidism could not be excluded on the basis of a serum cTSH concentration that was within the reference range. (J Am Vet Med Assoc 1998; 212:387-391)

Free access
in Journal of the American Veterinary Medical Association

Objective—

To determine the usefulness of measuring urine cortisol: creatinine ratio (UCCR) as a means of monitoring response to mitotane treatment in dogs with pituitary-dependent hyperadrenocorticism (PDH).

Design—

Case series.

Animals—

51 clinically normal dogs and 21 dogs with PDH.

Procedure—

The reference range for the UCCR was determined by measuring the ratio in 51 clinically normal dogs. The usefulness of measuring UCCR in evaluating response of 21 dogs with PDH to treatment with mitotane was evaluated by comparing ACTH-stimulated blood cortisol concentrations with UCCR at the end of the induction phase of treatment (13 dogs) and during the maintenance phase of treatment (21).

Results—

UCCR was not useful for identifying dogs with inadequate adrenal reserves at the end of the induction phase of treatment or during the maintenance phase. The UCCR was useful for identifying dogs in which control of cortisol secretion was not adequate.

Clinical Implications—

UCCR should not be used for evaluation of dogs during the induction phase of treatment, because the potential consequences of not identifying dogs with inadequate adrenal reserves are great. The UCCR may be useful as an adjunct means of monitoring treatment response during the maintenance phase of treatment However, the ACTH stimulation test remains a necessary component when monitoring response to treatment in dogs with PDH receiving mitotane. (J Am Vet Med Assoc 1997;210:1158–1161)

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in Journal of the American Veterinary Medical Association

Objective—

To evaluate the efficacy and safety of intravenous administration of human immune globulin in the treatment of dogs with immune-mediated hemolytic anemia (IMHA).

Design—

Prospective clinical trial.

Animals—

10 dogs with confirmed primary IMHA that had failed to respond to conventional immunosuppressive treatment (administration of prednisone and cyclophosphamide or azathioprine).

Procedure—

Diagnosis of IMHA was confirmed by detecting spherocytosis or autoagglutination in blood smears and by excluding secondary causes of IMHA. Dogs were treated with human immune globulin (1 g/kg (0.45 glib] of body weight. IV) during a 6- to 12-hour period. Prednisone treatment was continued in all dogs, and cyclophosphamide treatment was continued in 4.

Results—

Median duration of prior immunosuppressive treatment was 12.5 days. Short-term response could not be evaluated in 2 dogs, because they were given blood transfusions within 7 days after immune globulin treatment. However, there was a significant increase in mean Hct and hemoglobin concentration in 8 other dogs from day 0 to 28 after treatment. Five dogs had clinically meaningful responses to treatment. Three dogs were alive 12 months after treatment. There were not any adverse effects that could be definitively attributed to immune globulin treatment; however, thrombocytopenia was observed in 6 dogs after treatment, and evidence of thromboembolism was detected at necropsy in 5 of the 7 dogs that died.

Clinical Implications—

Human immune globulin may be useful for Short-term stabilization of some dogs with IMHA; however, it did not appear to improve long-term survival. (J Am Vet Med Assoc 1997;210:1623–1627)

Free access
in Journal of the American Veterinary Medical Association

Summary

Seven cats with thyroid carcinomas that had previously undergone surgical removal of neoplastic tissue were treated with 30 mCi of radioactive iodine (131I). Six of the cats had clinical signs of hyperthyroidism; 1 did not. There were no complications associated with 131I treatment, and clinical signs resolved in all cats. Technetium scans of 4 cats made after treatment did not have evidence of isotope uptake. In the remaining 3 cats, small areas of isotope uptake, the intensity of which was equal to or less than the intensity of uptake in the salivary glands, were seen. All 7 cats became hypothyroid after treatment; 4 required L-thyroxine supplementation. One cat was alive 33 months after treatment. The other 6 cats were euthanatized because of unrelated diseases 10 to 41 months after treatment.

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in Journal of the American Veterinary Medical Association

Summary

Outcome of and complications associated with bilateral adrenalectomy in 8 cats with pituitary-dependent hyperadrenocorticism and bilateral adrenocortical hyperplasia and outcome of and complications associated with unilateral adrenalectomy in 2 cats with adrenocortical tumor (adrenocortical adenoma, 1 cat; adrenocortical carcinoma, 1 cat) and unilateral adrenomegaly were determined. Glucocorticoids were administered to all cats at the time of surgery, and mineralocorticoids were administered to the 8 cats that underwent bilateral adrenalectomy. A ventral midline celiotomy was performed in all cats.

Intraoperative complications did not develop in any cat. Postoperative complications developed in all cats and included abnormal serum electrolyte concentrations (n = 8), skin lacerations (n = 5), pancreatitis (n = 3), hypoglycemia (n = 2), pneumonia (n = 1), and venous thrombosis (n = 1). Three cats died within 5 weeks after surgery of complications associated with sepsis (n = 2) or thromboembolism (n = 1). Clinical signs and physical abnormalities caused by hyperadrenocorticism resolved in the remaining 7 cats 2 to 4 months after adrenalectomy. Insulin treatment was discontinued in 4 of 6 cats with diabetes mellitus. Median survival time for these 7 cats was 12 months (range, 3 to > 30 months). Two cats died of acute adrenocortical insufficiency 3 and 6 months after bilateral adrenalectomy, 2 cats were euthanatized because of chronic renal failure 3 and 12 months after bilateral (n = 1) or unilateral (n = 1) adrenalectomy, and 2 cats were alive 9 and 14 months after bilateral adrenalectomy. In the remaining cat, clinical signs recurred 10 months after the cat had undergone unilateral adrenalectomy. The remaining adrenal gland was found to contain an adrenocortical adenoma and was removed. The cat was doing well when it was lost to follow-up 15 months after the second surgery.

Free access
in Journal of the American Veterinary Medical Association