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  • Author or Editor: J. Catharine Scott-Moncrieff x
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Abstract

Objective—To determine whether the increasing prevalence of feline hyperthyroidism is the result of aging of the cat population and whether consumption of canned foods at various times throughout life is associated with increased risk of hyperthyroidism.

Design—Retrospective and case-control studies.

Study Population—Medical records of 169,576 cats, including 3,570 cats with hyperthyroidism, evaluated at 9 veterinary school hospitals during a 20-year period, and 109 cats with hyperthyroidism (cases) and 173 cats without hyperthyroidism (controls).

Procedure—Age-adjusted hospital prevalence of hyperthyroidism was calculated by use of Veterinary Medical Database records. On the basis of owners' questionnaire responses, logistic regression was used to evaluate associations between consumption of canned food and development of hyperthyroidism.

Results—Age-specific hospital prevalence of feline hyperthyroidism increased significantly from 1978 to 1997. Overall, consumption of pop-top canned (vs dry) food at various times throughout life and each additional year of age were associated with greater risk of developing hyperthyroidism. In female cats, increased risk was associated with consumption of food packaged in pop-top cans or in combinations of pop-top and non-pop-top cans. In male cats, increased risk was associated with consumption of food packaged in pop-top cans and age.

Conclusions and Clinical Relevance—These findings suggest that the increasing prevalence of feline hyperthyroidism is not solely the result of aging of the cat population and that canned foods may play a role. (J Am Vet Med Assoc 2004;224:879–886)

Full access
in Journal of the American Veterinary Medical Association

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.

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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)

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in Journal of the American Veterinary Medical Association

Abstract

Objective

To evaluate interactions of human intravenous immunoglobulin (IVIG) with canine lymphocytes and monocytes.

Sample Population

Heparinized blood samples from 4 clinically normal Beagles.

Procedure

Binding ability of IVIG to canine lymphocytes and monocytes was measured by flow cytometry and an indirect immunofluorescent assay. Dualstaining fluorescent assays were done to determine lymphocyte subsets that bind IVIG. Competitive assays were done, using intact canine IgG and Fc fragments, and inhibition of binding was compared with that of F(ab)2 fragments. Ability of IVIG to inhibit phagocytosis of antibody-coated canine RBC also was determined, using a canine mononuclear cell phagocytic assay.

Results

IVIG concentrations (10, 1, 0.1, and 0.01 mg/ml) bound to (mean ± SD) 99.6 ± 0.4, 92.4 ± 6.1, 20.4 ± 24.6 and 2.0 ± 5.1% of canine lymphocytes, respectively, Dual staining analyses with IVIG and canine lymphocyte markers indicated that IVIG bound to CD4, CD8, and B lymphocytes. The aforementioned 4 IVIG concentrations bound to 98.0 ±2.1, 85.5 ± 13.5, 64.7 ± 32.8, and 26.5 ± 17.1% of monocytes, respectively. Inhibition of IVIG (0.01 mg/ml) binding to monocytes was significant (P < 0.05) in the presence of 1 and 10 mg of canine IgG/ml and 1 mg of canine Fc fragments/ml. In the presence of F(ab')2 fragments of canine IgG, inhibition was not significant, suggesting that binding is Fc mediated. Co-culturing of monocytes, opsonized RBC, and the 4 concentrations of IVIG and no IVIG resulted in 11.8 ± 5.1, 27.7 ± 12.3, 31.8 ± 15.1, 53.8 ± 6.7, and 45 ± 12% of the monocytes containing RBC, respectively. Phagocytosis inhibition was significant (P < 0.05) at an IVIG concentration of 10 mg/ml.

Conclusions

IVIG binds to canine lymphocytes and monocytes; binding to the latter is Fc mediated. IVIG also inhibits Fc-mediated phagocytosis of antibody-coated RBC.

Clinical Relevance

Owing to its ability to inhibit Fc-mediated phagocytosis of antibody-coated RBC, IVIG may be an effective short-term treatment for dogs with immune-mediated hemolytic anemia. (Am J Vet Res 1998;59:1568-1574)

Free access
in American Journal of Veterinary Research

Objective—

To assess clinical signs, biochemical findings, results of modified water deprivation and other diagnostic tests, response to treatment, and survival time in dogs with central diabetes insipidus (CDI).

Design—

Retrospective study.

Animals—

20 dogs with CDI.

Procedure—

Signalment, history, physical examination, results of diagnostic tests, response to treatment, and survival time were extracted from the medical record of each dog and supplemented with information obtained from owners via telephone.

Results—

Isosthenuria or hyposthenuria was a consistent finding. Seven dogs with complete CDI and 13 dogs with partial CDI were identified on the basis of results of a modified water deprivation test. Dogs treated with desmopressin acetate responded well to treatment. Seven dogs were alive 18 to 72 months (median, 36 months) after diagnosis, and 10 dogs died or were euthanatized 1 week to 2 years (median, 2 months) after diagnosis. Seven of 10 dogs that died developed neurologic signs after diagnosis of CDI. Computed tomography revealed a mass in the region of the pituitary gland in 5 of 7 dogs. Necropsy of 6 dogs, including 2 dogs on which computed tomography had been performed, revealed neoplasia in the pituitary gland.

Clinical Implications—

Onset of neurologic signs after diagnosis of CDI in middle- to old-aged dogs indicates that CDI may not be a benign disease that is treated easily. Brain imaging is recommended after diagnosis of CDI in middle- to old-aged dogs. Also, because many dogs are isosthenuric on initial examination, CDI cannot be ruled out as a cause of polyuria and polydipsia on the basis of lack of hyposthenuria. (J Am Vet Med Assoc 1996;209:1884–1888)

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in Journal of the American Veterinary Medical Association

Objective—

To validate a new immunoradiometric assay for canine thyroid-stimulating hormone (cTSH) and to document changes in serum cTSH concentration during induction of hypothyroidism in dogs.

Animals—

Six healthy adult male Beagles.

Procedure—

Sensitivity, specificity, precision, and accuracy of the cTSH assay were evaluated in vitro. Hypothyroidism was induced in dogs by IV administration of sodium iodide I 131 solution. Subsequently, l-thyroxine was administered orally to normalize serum thyroxine concentrations.

Results—

The cTSH assay appeared to be specific and was sufficiently sensitive to detect cTSH in the serum of these dogs prior to induction of hypothyroidism. There was a 35-fold increase in mean serum cTSH concentration following induction of hypothyroidism, and 35 days after initiation of thyroid replacement therapy, mean serum cTSH concentration was not significantly greater than mean baseline value.

Clinical Implications—

Assay of serum cTSH is likely to prove helpful in the differential diagnosis of primary, secondary, and tertiary hypothyroidism in dogs, and in monitoring response to thyroid hormone replacement treatment. (J Am Vet Med Assoc 1996;209:1730–1732)

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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.

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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

Abstract

Objective—To determine the effect of natural exposure to domoic acid (DA) on eosinophil counts and adrenal gland function in California sea lions (Zalophus californianus).

Design—Cross-sectional prospective study.

Animals—39 California sea lions.

Procedures—Adult female sea lions admitted to a rehabilitation hospital during 2009 were classified into 1 of 3 groups (acute DA toxicosis, chronic DA toxicosis, or no DA exposure) on the basis of clinical signs, DA concentration in urine or feces, and hippocampal morphology. Endoparasite burden, eosinophil count, and serum cortisol and plasma ACTH concentrations were determined for each sea lion. For a subset of 8 sea lions, fecal glucocorticoid concentration after IM administration of cosyntropin was determined.

Results—Sea lions exposed to DA (acute DA toxicosis, n = 11; chronic DA toxicosis, 19) had higher eosinophil counts and lower serum cortisol concentrations, compared with values for sea lions with no DA exposure (9). Eosinophil count was not associated with endoparasite burden. Serum cortisol concentration was associated with plasma ACTH concentrations in sea lions from the no DA exposure group but not in sea lions in the acute or chronic DA toxicosis groups. Following cosyntropin injection, fecal glucocorticoid concentrations increased in all sea lions evaluated except 1.

Conclusions and Clinical Relevance—In adult sea lions, eosinophilia may be a cost-effective biomarker for DA exposure and may reflect alterations in hypothalamic, pituitary gland, or adrenal gland function. Domoic acid exposure may have subtle health effects on marine animals in addition to induction of neurologic signs.

Full access
in Journal of the American Veterinary Medical Association