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

Objective

To determine whether exotoxin production by Staphylococcus intermedius is an important factor in recurrence of pyoderma in atopic dogs.

Design

Prospective clinical study.

Animals

30 client-owned dogs (10 clinically normal dogs, 10 atopic dogs with recurrent pyoderma, and 10 dogs with a single episode of pyoderma).

Procedure

Specimens for bacterial culturing were obtained from a pustule or papule of affected dogs or from skin of clinically normal dogs. Staphylococcus intermedius was isolated and processed. Supernatants were analyzed for staphylococcal exotoxins. Types of lesions and severity of pruritus were assessed for each dog.

Results

Exotoxins A and C were detected in S intermedius isolated from 1 clinically normal dog. In the atopic group, exotoxin C was isolated from 1 dog, exotoxins A and C were isolated from 1 dog, and exotoxin C and toxic shock syndrome toxin-1 were isolated from 1 dog. Exotoxins were isolated from 2 dogs with a single episode of pyoderma (exotoxin C, 1 dog; exotoxins A and C, 1 dog). Lesion types and severity of pruritus varied greatly among dogs with pyoderma and were not associated with detection of exotoxin or type of exotoxin.

Clinical Implications

Exotoxins were identified from few isolates of S intermedius, and we did not observe an association between type of lesions or severity of pruritus and detection of exotoxins. Production of exotoxin by S intermedius does not play a role in the recurrent nature of pyoderma in atopic dogs or on type of lesion or severity of pruritus associated with pyoderma. (J Am Vet Med Assoc 1998;213:232-234)

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in Journal of the American Veterinary Medical Association

Summary:

We compared efficacy of cefadroxil and generic and proprietary cephalexin in treatment of pyoderma in dogs. Forty-four dogs were randomly assigned to receive 1 of the 3 preparations at 22 to 35 mg/kg body weight, every 12 hours. Dogs were examined at the conclusion of treatment period and assessed as to degree of improvement. All 3 cephalosporins were effective and safe antibiotics for the treatment of pyoderma in dogs.

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in Journal of the American Veterinary Medical Association

Objective

To evaluate the biological stability of reconstituted cosyntropin after storage at −20 C for 2, 4, and 6 months.

Design

Prospective study.

Animals

10 clinically normal dogs.

Procedure

Serum cortisol concentrations in dogs were determined before and 1 hour after administration of freshly reconstituted cosyntropin (synthetic ACTH) or cosyntropin that had been reconstituted and stored frozen at −20 C in plastic syringes for 2, 4, and 6 months. Cosyntropin was administered at 5 μg/kg (2.3 μg/lb) of body weight, IV.

Results

Baseline serum cortisol concentrations were similar at each sampling time. Compared with the effects of freshly reconstituted cosyntropin, administration of cosyntropin that had been frozen did not have a significantly different effect on serum cortisol concentrations.

Clinical lmplications

Cosyntropin can be reconstituted and stored frozen at −20 C in plastic syringes for 6 months with no adverse effects on bioactivity of the polypeptide. (J Am Vet Med Assoc 1998;212: 1569–1571)

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in Journal of the American Veterinary Medical Association

Summary

Serum cortisol concentration was evaluated in 71 dogs before and after a stressful procedure was performed. Thirty dogs were skin tested with sedation (group S), 21 dogs were skin tested without sedation (group NS), and 20 dogs had other dermatologic procedures performed (group C). Group-S dogs had significant (P < 0.001) decrease in serum cortisol concentration after skin testing, compared with baseline values. In contrast, dogs of groups NS and C had significant (P < 0.001) increase in poststress serum cortisol concentration. Mean cortisol concentration after stress was significantly lower for dogs of group S, compared with that for dogs of the other 2 groups.

The second part of the analysis consisted of determining the number of false-negative skin test results for dogs of groups S and NS and comparing these with serum cortisol concentration. Difference in the number of suspected atopic dogs with negative skin test results (false-negative) was not evident between groups S and NS. Also, difference was not apparent between cortisol concentration in dogs that had positive or false-negative skin test results in either group. This finding indicates that high serum cortisol concentration does not affect results of skin testing in suspected atopic dogs.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare the effects of 2 doses of cosyntropin (5 µg/kg vs 250 µg, IV) on serum concentrations of cortisol, sex hormones of adrenal origin, and adrenocortical steroid intermediates and determine the optimal sample collection time after adrenal stimulation with cosyntropin.

Animals—10 healthy, privately owned, neutered dogs.

Procedure—Dogs were randomly assigned to initially receive cosyntropin at 5 µg/kg or as a total dose of 250 µg, IV. Dogs received the alternate dose 1 to 2 weeks later. Serum was obtained from blood samples collected before (0 minutes) and 30, 60, 90, and 120 minutes after cosyntropin administration.

Results—Maximum stimulation of cortisol, androstenedione, progesterone, and 17-hydroxyprogesterone production was achieved at 60 minutes following IV administration of cosyntropin at 5 µg/kg or as a total dose of 250 µg. Serum estradiol concentration did not increase in response to either cosyntropin dose. For all hormones, no significant difference in serum hormone concentrations was found among sample collection times of 0, 30, 60, and 90 minutes when comparing the 2 doses of cosyntropin.

Conclusions and Clinical Relevance—Cosyntropin, when administered at 5 µg/kg, IV, effectively stimulated maximum production of cortisol, sex hormones of adrenal origin, and adrenocortical steroid intermediates at 1 hour after administration. (Am J Vet Res 2004;65:1631–1633)

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in American Journal of Veterinary Research

Abstract

Objective—To determine whether the stress of an ultrasonographic procedure would interfere with the suppressive effect of dexamethasone during a lowdose dexamethasone suppression test (LDDST) in healthy dogs.

Animals—6 clinically normal adult dogs.

Procedure—In phase 1, an LDDST was performed 5 times at weekly intervals in each dog. Serum samples were obtained 0, 2, 4, 6, and 8 hours after dexamethasone injection. A mock 20-minute abdominal ultrasonographic examination was performed on all dogs at each time point during the LDDST on weeks 2 through 5. In phase 2, serum cortisol concentrations were measured before and immediately after a 20-minute mock abdominal ultrasonographic examination, as described for phase 1.

Results—We did not detect significant differences after dexamethasone injection when comparing median cortisol concentrations for weeks 2 to 5 (mock ultrasonographic procedure) with median concentration for week 1 (no mock ultrasonographic procedure). For 5 of the 6 dogs, cortisol concentrations after dexamethasone injection decreased to < 35.9 nmol/L after each mock ultrasonographic procedure and remained low for the duration of the LDDST. In phase 2, all dogs had significant increases in cortisol concentrations immediately after the mock ultrasonographic procedure.

Conclusions and Clinical Relevance—A 20-minute mock abdominal ultrasonographic examination performed during LDDST did not alter results of the LDDST in most dogs. Cortisol concentrations measured immediately after a mock ultrasonographic examination were significantly increased. Ultrasonographic procedures should be performed a minimum of 2 hours before collection of samples that will be used to measure cortisol concentrations. ( Am J Vet Res 2004;65:267–270)

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in American Journal of Veterinary Research

Abstract

Objective—To determine how rapidly trimethoprimsulfamethoxazole affects serum total thyroxine (T4) and thyroid-stimulating hormone (TSH) concentrations in euthyroid dogs and how quickly hormone concentrations return to reference values following discontinuation of administration.

Design—Prospective study.

Animals—7 healthy euthyroid dogs.

Procedure—Dogs were given trimethoprim-sulfamethoxazole (26.5 to 31.3 mg/kg [12 to 14.2 mg/lb], PO, q 12 h) for a maximum of 6 weeks. A CBC and Schirmer tear test were performed and serum total T4 and TSH concentrations were measured weekly. Administration of trimethoprim-sulfamethoxazole was discontinued if total T4 concentration was less than the lower reference limit and TSH concentration was greater than the upper reference limit or if persistent neutropenia developed.

Results—Six dogs had total T4 concentrations less than the lower reference limit within 3 weeks; T4 concentration was decreased after 1 week in 3 of these 6 dogs. In these 6 dogs, TSH concentration was greater than the upper reference limit within 4 weeks. In 1 dog, T4 and TSH concentrations were not affected, despite administration of trimethoprimsulfamethoxazole for 6 weeks. Neutropenia developed in 4 dogs. In 1 dog, the neutropenia resolved while trimethoprim-sulfamethoxazole was still being administered. In the other 3, neutrophil counts returned to reference values 1 week after drug administration was discontinued.

Conclusions and Clinical Relevance—Results suggest that administration of trimethoprim-sulfamethoxazole at a dosage of 26.5 to 31.3 mg/kg, PO, every 12 hours can substantially alter serum total T4 and TSH concentrations and neutrophil counts in dogs within as short a time as a few weeks. (J Am Vet Med Assoc 2002;221:802–806)

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in Journal of the American Veterinary Medical Association

Abstract

Objective

To determine the distribution and amount of elastic fibers in the dermis of clinically normal dogs and dogs with dermatoses, particularly solar dermatitis.

Design

Skin specimens from 7 anatomic sites were obtained from 19 clinically normal dogs after euthanasia to evaluate the normal distribution o elastic fibers. Biopsy specimens also were obtained from 34 dogs with dermatoses, including 16 with solar dermatitis. Tissue sections were stained with H&E, Verhoeff-van Gieson, and periodic acid-Schiff.

Animals

19 clinically normal dogs and 34 dogs with dermatoses.

Procedure

Numbers of elastic fibers were graded subjectively. Comparisons between clinically normal dogs and dogs with dermatoses were made.

Results

Normal elastic fibers were present in low numbers in the dermis of adult dogs, regardless of anatomic site or presence or severity of dermatitis. Condensed elastotic material was visualized in only 2 dogs with solar dermatitis. In both dogs, the elastotic material was Verhoeff-van Gieson and periodic acid-Schiff stain positive but was not visible with H&E stain. The most frequent histopathologic finding in the dermis of dogs with solar dermatitis was superficial dermal fibrosis.

Conclusions

The dermis of clinically normal dogs does not contain abundant elastic fibers. Alterations of elastic fibers in dogs with solar dermatitis are rare. Superficial dermal fibrosis may be a better indicator of solar damage.

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in American Journal of Veterinary Research