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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.

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

SUMMARY

Glutamine has been shown to be an important metabolic substrate of enterocytes in many animals, including cats, dogs, hamsters, human beings, monkeys, rabbits, rats, and sheep. To determine whether glutamine is important in the metabolism of cells of the equine gastrointestinal tract, we examined transintestinal differences in glutamine concentrations in the arterial and venous circulation, and measured activity of the major glutamine catabolizing enzyme, glutaminase. Arteriovenous differences provide an index of the amount of a given substrate removed by the tissue across which the measurements are made, and commonly are expressed as a percentage of substrate removed, or percent extraction. Arteriovenous differences for glutamine were determined in 7 anesthetized adult horses (weight, 450 to 500 kg) before and after an iv glutamine infusion. The mean baseline arterial glutamine concentration (± sem) was 572 ± 24 μM; this concentration quadrupled (to 2,167 ± 135 μM, P < 0.01) 1 minute after iv bolus infusion of a 17.5-g glutamine load. Baseline extraction by the portal-drained viscera was 7.5 ± 1.5%; this value increased to 18 ± 2% at 1 minute (P < 0.01) and had returned to baseline values 60 minutes later. Arteriovenous differences were greatest across the jejunum (11.8 ± 1.8% in the baseline period vs 33.1 ± 3.1% at 1 minute, P < 0.001), with smaller differences across the colon, suggesting that the jejunum was the more avid utilizer of glutamine. Glutaminase activity was 4.38 ± 0.16 and 4.00 ± 0.60 μmol/mg of protein/h under standard conditions in jejunal and ileal mucosa, respectively. Kinetic studies of jejunal glutaminase revealed the enzyme to have a Km of 3.81 ± 0.35 mM and a Vmax of 8.08 ± 0.54 μmol/mg of protein/h, suggesting that the small intestine of horses has a high capacity to extract and metabolize circulating glutamine.

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

Abstract

Objective

To determine adverse effects of single and multiple doses of liposome-encapsulated cis-bis-neodecanoato-trans-R, R-1, 2-diaminocyclohexane platinum (II) (L-NDDP) administered IV to healthy adult cats.

Animals

10 healthy adult cats.

Procedure

8 cats were given a single dose of L-NDDP (at rates of 75, 100, 150, or 200 mg/m2), and 2 cats were given liposomal lipid (1,500 mg/m2). Six of the 10 cats were given doses of L-NDDP at the maximum tolerated dosage (100 mg/m2) or a lower dosage (75 mg of L-NDDP/m2) at 21-day intervals, for a total of 4 treatments. Hematologic and serum biochemical analyses, urinalyses, and physical examinations were used to monitor effects of L-NDDP.

Results

All cats had transient pyrexia, lethargy, vomiting (1 to 3 times/24 h), inappetence, and an acute species-specific infusion reaction that was prevented by administration of atropine-diphenhydramine. Dose-limiting toxicosis was evident as a 10- day course of lethargy, intermittent vomiting, and diarrhea. In cats given multiple doses, dose-related thrombocytopenia, cumulative myelosuppression, transient increased hepatic transaminase activity, and mild to moderate hepatic hydropic degeneration and proximal renal tubular lipidosis in excess of lipidosis expected for this species were detected. Bone marrow hypoplasia was detected in some cats that received higher doses (cumulative dosages of 300 or 400 mg of L-NDDP/m2).

Conclusion

Cats can safely be given L-NDDP at potentially therapeutic dosages without inducing renal or pulmonary toxicoses.

Clinical Relevance

Because L-NDDP has better tumoricidal activity than cisplatin (in vivo and in vitro) and is not cross resistant, it may be similarly or more efficacious than cisplatin in humans and dogs. (Am J Vet Res 1999;60:257–263)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine clinical response and toxic effects of cis-bis-neodecanoato-trans-R,R-1,2- diaminocyclohexane platinum (II) (L-NDDP) administered IV at escalating doses to cats with oral squamous cell carcinoma (SCC).

Animals—18 cats with oral SCC.

Procedure—Cats that failed to respond to conventional treatment or had nonresectable tumors were included. Data included a CBC, serum biochemical analyses, urinalysis, cytologic examination of a fineneedle aspirate of enlarged lymph nodes, and thoracic and oral radiographs for clinical staging. A starting dose (75 to 100 mg/m2 of L-NDDP) was administered IV. At 21-day intervals, subsequent doses increased by the rate of 5 or 10 mg/m2. Response was evaluated every 21 days by tumor measurement and thoracic radiography. Quality of life was assessed by owners, using a performance status questionnaire.

Results—On average, cats received 2 treatments. Toxicoses included an intermittent, acute anaphylactoid- parasympathomimetic reaction, lethargy or sedation (≤ 24 hours), inappetence or signs of depression (≤ 72 hours), mild to moderate increase in hepatic enzyme activity, and melena. Pulmonary, renal, or hematopoietic abnormalities were not evident. Performance status surveys indicated normal behavior and grooming or decreased activity and self-care (19/20 assessments), ate well with or without assistance (15/20), and did not lose weight (15/20). Median survival time was 59.8 days (mean, 54.1 days).

Conclusions and Clinical Relevance—L-NDDP was ineffective for treatment of cats with oral SCC. None of the cats had a complete or partial remission. Acute toxicoses and poor therapeutic response limit therapeutic usefulness of L-NDDP in cats, unless dosage, frequency, and administration procedures can be improved. (Am J Vet Res 2000;61: 791–795)

Full access
in American Journal of Veterinary Research