Isolation of Staphylococcus schleiferi from healthy dogs and dogs with otitis, pyoderma, or both.

OBJECTIVE: To determine the frequency of isolation and susceptibility patterns of Staphylococcus schleiferi from healthy dogs and dogs with otitis, pyoderma, or both that had or had not received antimicrobial treatment. DESIGN: Prospective study. ANIMALS: 50 dogs. PROCEDURE: Dogs were allocated to 1 of 4 groups: healthy dogs (n=13), dogs without otitis but with pyoderma (10), dogs with otitis but without pyoderma (11), and dogs with otitis and pyoderma (16). Bacteriologic culture of ear swab specimens was performed in all dogs. Bacteriologic culture of skin swab specimens was also performed in dogs with concurrent pyoderma. Isolates were identified as S schleiferi subsp schleiferi or S schleiferi subsp coagulans on the basis of growth and biochemical characteristics. RESULTS: S schleiferi was not isolated from any dogs with pyoderma only. Staphylococcus schleiferi subsp schleiferi was isolated from the ears of 2 healthy dogs, and the skin and ears of 2 dogs and the skin of 1 dog with otitis and pyoderma. Staphylococcus schleiferi subsp coagulans was isolated from the ears of 3 dogs with otitis only, and the ears of 6 dogs and the skin of 2 dogs with otitis and pyoderma. One of the S schleiferi subsp schleiferi isolates from ears, 2 of the S schleiferi subsp coagulans isolates from ears, and 1 of the S schleiferi subsp coagulans isolates from the skin were resistant to methicillin. One methicillin-resistant isolate from the ears and 1 from the skin were also resistant to fluoroquinolones. CONCLUSIONS AND CLINICAL RELEVANCE: S schleiferi subsp schleiferi was detected in healthy dogs and dogs with otitis and pyoderma. Methicillin-resistant and -susceptible S schleiferi subsp schleiferi and S schleiferi subsp coagulans were detected as the predominant organisms in dogs with otitis.

Effects of sulfamethoxazole-trimethoprim on thyroid function in dogs.

OBJECTIVE: To evaluate effects of trimethoprim-sulfamethoxazole (T/SMX) on thyroid function in dogs. ANIMALS: 6 healthy euthyroid dogs. PROCEDURE: Dogs were administered T/SMX (14.1 to 16 mg/kg, PO, q 12 h) for 3 weeks. Blood was collected weekly for 6 weeks for determination of total thyroxine (TT4), free thyroxine (fT4), and canine thyroid-stimulating hormone (cTSH) concentrations. Schirmer tear tests were performed weekly. Blood was collected for CBC prior to antimicrobial treatment and at 3 and 6 weeks. RESULTS: 5 dogs had serum TT4 concentrations equal to or less than the lower reference limit, and 4 dogs had serum fT4 less than the lower reference limit after 3 weeks of T/SMX administration; cTSH concentrations were greater than the upper reference limit in 4 dogs. All dogs had TT4 and fT4 concentrations greater than the lower reference limit after T/SMX administration was discontinued for 1 week, and cTSH concentrations were less than reference range after T/SMX administration was discontinued for 2 weeks. Two dogs developed decreased tear production, which returned to normal after discontinuing administration. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that administration of T/SMX at a dosage of 14.1 to 16 mg/kg, PO, every 12 hours for 3 weeks caused decreased TT4 and fT4 concentrations and increased cTSH concentration, conditions that would be compatible with a diagnosis of hypothyroidism. Therefore, dogs should not have thyroid function evaluated while receiving this dosage of T/SMX for >2 weeks. These results are in contrast to those of a previous study of trimethoprim-sulfadiazine.

Adrenal steroid hormone concentrations in dogs with hair cycle arrest (Alopecia X) before and during treatment with melatonin and mitotane.

The purpose of the study was to evaluate intermediate adrenal steroid hormones (ISH) in neutered dogs with hair cycle arrest (Alopecia X) during treatment with melatonin, and to see if hair re-growth is associated with sex hormone concentrations within the normal ranges. Twenty-nine neutered, euthyroid, and normo-cortisolemic dogs were enrolled in the study (23 Pomeranians, three keeshonds, two miniature poodles, and one Siberian husky). Coat assessment and an ACTH stimulation test were performed pre-treatment and approximately every 4 months for a year post treatment. Melatonin was administered initially at 3-6 mg, every 12 h. Based on clinical progression, each dog was continued on the current dose of melatonin, given an increased dose of melatonin or changed to mitotane. Partial to complete hair re-growth occurred in 14/23 Pomeranians, and partial re-growth in 3/3 keeshond and 1/2 poodle dogs. A Siberian husky dog failed to re-grow hair. Fifteen dogs had partial hair re-growth at the first re-evaluation. Melatonin dosage was increased in eight dogs but only one had improved hair re-growth. On mitotane treatment, partial to complete hair re-growth was seen in 4/6 dogs and no re-growth in 2/6 dogs. No significant decrease in sex hormone concentrations were seen during melatonin or mitotane treatment. Concentrations of ISH in dogs with hair re-growth did not differ significantly from pre-treatment values. At the completion of the study, androstenedione, progesterone and 17-hydroxyprogesterone were still above reference ranges in 21, 64 and 36%, respectively, of dogs with partial to complete hair re-growth. In conclusion, 62% of dogs had partial to complete hair re-growth. However, not all dogs with hair re-growth had concentrations of ISH within the normal range.

Effects of a mock ultrasonographic procedure on cortisol concentrations during low-dose dexamethasone suppression testing in clinically normal adult dogs.

OBJECTIVE: To determine whether the stress of an ultrasonographic procedure would interfere with the suppressive effect of dexamethasone during a low-dose 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.

Retrospective evaluation of sex hormones and steroid hormone intermediates in dogs with alopecia.

The purpose of this study was to determine if there are specific steroid hormone aberrations associated with suspect endocrine alopecias in dogs in whom hypothyroidism and hyperadrenocorticism have been excluded. Steroid hormone panels submitted to the UTCVM endocrinology laboratory over a 7.5-year period (783 samples) from dogs with alopecia were reviewed. During this period, 276 dogs met the criteria for inclusion and were comprised of 54 different breeds. Approximately 73% of dogs had at least one baseline or post-ACTH stimulation steroid hormone intermediate greater than the normal range. The most frequent hormone elevation noted was for progesterone (57.6% of samples). When compared with normal dogs, oestradiol was significantly greater in Keeshond dogs and progesterone was significantly greater in Pomeranian and Siberian Husky dogs. Not all individual dogs had hormone abnormalities. Chow Chow, Samoyed and Malamute dogs had the greatest percentage of normal steroid hormone intermediates of the dogs in this study. Baseline cortisol concentrations were significantly correlated with progesterone, 17-hydroxyprogesterone (17-OHP) and androstenedione. Results of this study suggest that the pathomechanism of the alopecia, at least for some breeds, may not relate to steroid hormone intermediates and emphasizes the need for breed specific normals.

Isolation of Staphylococcus schleiferi from dogs with pyoderma.

OBJECTIVE: To determine frequency with which Staphylococcus schleiferi could be isolated from dogs with pyoderma and antimicrobial susceptibility patterns of isolates that were obtained. DESIGN: Prospective study. ANIMALS: 54 dogs with a first (n = 14) or recurrent (40) episode of pyoderma. PROCEDURE: Specimens were obtained and submitted for bacterial culture. Isolates were identified as S schleiferi on the basis of growth and biochemical characteristics. Two isolates were submitted for DNA sequencing to confirm identification. Methicillin susceptibility was determined by means of disk diffusion with oxacillin-impregnated disks. RESULTS: 3 of 14 dogs examined because of a first episode of pyoderma and 12 of 40 dogs examined because of a recurrent episode of pyoderma were receiving antimicrobials at the time of specimen collection. Staphylococcus schleiferi was not isolated from any dog with first-time pyoderma but was isolated from 5 dogs with recurrent pyoderma that were not receiving antimicrobials at the time of specimen collection and 10 dogs with recurrent pyoderma that were receiving antimicrobials. Nine isolates were identified as S schleiferi subsp schleiferi, and 6 were identified as S schleiferi subsp coagulans. All S schleiferi subsp schleiferi isolates were resistant to methicillin, but only 2 S schleiferi subsp coagulans isolates were. Two methicillin-resistant isolates were also resistant to fluoroquinolones, and 1 isolate had intermediate susceptibility to fluoroquinolones. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that S schleiferi subsp schleiferi and S schleiferi subsp coagulans may be isolated from dogs with recurrent pyoderma. Although isolates from dogs with pyoderma were frequently resistant to methicillin, multiple drug resistance was uncommon.

Effects of short-term trimethoprim-sulfamethoxazole administration on thyroid function in dogs.

OBJECTIVE: To determine how rapidly trimethoprim-sulfamethoxazole 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 trimethoprim-sulfamethoxazole 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.

Effect of topical application of fipronil in cats with flea allergic dermatitis.

OBJECTIVE: To determine whether topical application of a 10% fipronil solution would control signs of flea allergic dermatitis in cats housed under natural conditions. DESIGN: Multicenter open clinical trial. ANIMALS: 42 client-owned cats with flea allergic dermatitis. PROCEDURES: Study cats along with all other cats and dogs living in the same houses were treated with 10% fipronil solution topically on days 0, 30, and 60. Flea counts and clinical assessments were performed on study cats on days 0, 14, 30, 60, and 90. RESULTS: Percentage reductions in geometric mean flea counts on days 14, 30, 60, and 90, compared with day-0 geometric mean count, were 75, 73, 85, and 94%, respectively. Pruritus score was significantly improved at each examination after day 0, and pruritus was reduced or eliminated in 31 of 40 (78%) cats at the final examination. Similarly, scores for severity of miliary dermatitis and alopecia were significantly improved at each examination, except for alopecia score on day 14. Overall treatment efficacy, assessed on day 90, was excellent for 28 (70%) cats, good for 6 (15%), moderate for 3 (7.5%), and poor for 3 (7.5%). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that monthly topical application of fipronil is effective for treatment of flea allergic dermatitis in cats housed under natural conditions.

Evaluation of topically applied enilconazole for the treatment of dermatophytosis in a Persian cattery.

Many Persian catteries have long-standing dermatophyte infections and are particularly difficult to treat. Enilconazole is a topical antifungal agent that has demonstrated good efficacy in recent studies. Twenty-two Persian cats naturally infected with Microsporum canis in a breeding cattery were treated with topical 0.2% enilconazole and monitored for 180 days. The treatments were repeated every 3 days for a total of eight applications. All the cats improved clinically and became culture negative by day 28. By day 180, four cats had developed clinical dermatophytosis and all cats had positive fungal cultures. In this study, topical 0.2% enilconazole was generally well tolerated but may have caused hypersalivation, idiopathic muscle weakness and slightly elevated serum alanine aminotransferase (ALT) concentrations. This study suggests that enilconazole may be used safely with little risk to the young, aged and gravid animals.

Dermatophyte granulomas caused by Trichophyton mentagrophytes in a dog.

Multiple, dermal and subcutaneous nodules developed in a young female Manchester Terrier dog that had a chronic history of superficial dermatophytosis. Skin biopsy specimens of the nodules revealed granulomatous inflammation in the deep dermis and subcutis with branching fungal organisms. Cultures of multiple biopsy specimens from the nodules all yielded Trichophyton mentagrophytes. The lesions in this dog were similar to granulomatous dermatophytosis, a skin disease that has been reported in Persian cats and one Yorkshire Terrier dog.