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Objective: To evaluate histologic reactions to 8 suture materials and cyanoacrylate tissue adhesive (CTA) in the musculature and skin of ball pythons., Animals: 30 hatchling ball pythons., Procedures: In each snake, ten 1-cm skin incisions were made (day 0). At 8 sites, a suture of 1 of 8 materials was placed in the epaxial musculature, and the incision was closed with the same material. One incision was closed by use of CTA. No suture material was placed in the tenth incision, which was allowed to heal by second intention (negative control). Snakes (n = 5/group) were euthanized for harvest of treatment-site tissues at days 3, 7, 14, 30, 60, and 90. Skin and muscle sections were examined microscopically and assigned a subjective score (0 to 4) for each of the following: overall severity of inflammation, fibrosis, number of macrophages, number of granulocytes, number of perivascular lymphocytes, and degree of suture fragmentation., Results: Subjective score analysis revealed that CTA did not cause a significant inflammatory response, compared with the negative control. All suture materials caused significantly more inflammation over all time points; for all suture materials, inflammatory response scores were significantly higher than values for the negative control 90 days after implantation. No sutures were completely absorbed by the end of the study period, and several sutures appeared to be in the process of extrusion., Conclusions and Clinical Relevance: In snakes, CTA can be used to close small superficial incisions or lacerations with minimal inflammatory response, and sutures may undergo extrusion from tissues prior to complete absorption.

Objective: To document uterine growth and microvascular development in the endometrium of uteri with differing degrees of fibrosis as well as uterine growth throughout the estrous cycle of mares., Animals: 30 mares., Procedure: Uterine tissue was obtained during the breeding season from a slaughter facility. Stage of estrous cycle of the mares was assessed on the basis of ovarian structures and plasma progesterone concentrations. Endometrium was characterized by use of light microscopy, and blood vessel walls were marked by histochemical techniques. Microvascular development was evaluated by a computerized image analysis system. Growth of uterine tissue was based on cellular content of DNA and RNA, RNA:DNA, and protein:DNA., Results: Significant differences in vascular density were not observed in the endometrium of uteri obtained from mares euthanatized during the follicular or luteal phase of the estrous cycle, regardless of whether endometrial classification of degree of fibrosis was considered. There was a 3-fold increase in amount of DNA and RNA of endometrial cells in the follicular phase when compared to myometrium. Hypertrophy of endometrial tissue during the luteal phase was reflected by a significant increase in cell protein content and protein:DNA., Conclusions and Clinical Relevance: Endometrial growth of vascular tissues during the estrous cycle may be coordinated with development of nonvascular tissue. Estrogen and progesterone may play a role in regulation of uterine growth and angiogenesis.

Objectives: To develop an objective, quantifiable assay for endometrial periglandular fibrosis (EPF) and correlate assay results with histologic and ultrastructural changes in equine endometrial biopsy specimens., Sample Population: Endometrial biopsy specimens from 70 mares from 3 to 27 years old in estrus., Procedure: In a double-blinded study design, endometrial biopsy specimens were graded histologically (modified Kenney classification) for EPF and inflammation. Endometrial periglandular collagen volume fraction (%EPCVF) was determined by light microscopic image analysis of picrosirius red-stained sections. Specimens from selected mares were examined by transmission electron microscopy., Results: %EPCVF values varied significantly among the 4 modified Kenney EPF categories (I, IIA, IIB, and III) and increased with increasing age of mares. Morphologically, EPF consisted of concentric layers of transformed fibroblasts with myofibroblastic features and deposition of fibrillar collagen around unaltered glandular basal laminae., Conclusions and Clinical Relevance: %EPCVF correlates well with morphologic changes in endometrial biopsy specimens. Determination of %EPCVF could be useful in evaluation and clinical management of subfertile mares and in investigations of the pathogenesis of EPF.

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 of 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.

Objective: To develop a protocol for reliably inducing atrioventricular (AV) block (ideally first- or second-degree), using radiofrequency energy., Design: An electrosurgical unit was coupled to an ammeter, which was connected to the distal pole of an electrode catheter positioned at the AV node. Control settings had previously been calibrated to the power output in a circuit with a 100-ohm resistance., Animals: 10 clinically normal dogs., Procedure: Transcatheter AV nodal modification was attempted, using progressive power applications of 10 to 20 W for progressive durations of 10 to 30 seconds. Atrioventricular nodal conduction and refractivity were measured before and 20 minutes and 1 month after ablation. Electrocardiograms were monitored throughout the 1-month period., Results: Eight of the 10 dogs developed complete AV block, I developed stable 2:1 AV block, and another had no long-term change in AV nodal conduction. Four dogs attained their maximal degree of AV block in 2 to 5 days. Three of these had no AV nodal conduction changes until 2 to 4 days after ablation., Conclusions: An electrosurgical unit can be economically modified for radiofrequency transcatheter ablation. Stable, incomplete AV block was rarely induced using this protocol, whereas complete AV block often developed. A major finding was frequent delay between energy delivery to the AV nodal region and induction of AV block., Clinical Relevance: Induction of complete AV block using this technique, followed by permanent pacemaker placement, is an effective alternative to long-term antiarrhythmic treatment in animals with chronic atrial arrhythmias. Transcatheter ablation could be used to treat other forms of tachycardia, as it is in human medicine.

Two groups of 4 dogs underwent nasal and ethmoidal turbinectomies followed by irradiation (mean minimal) doses of 5,390 and 6,550 cGy of radiation, respectively) from implanted intracavitary sources of iridium 192. Two dogs from each group were euthanatized for histologic evaluation at 3 months after irradiation. The remaining 2 dogs from each group were euthanatized for similar evaluation at 6 months after irradiation. During the course of the study, few clinical complications were encountered. Histologic evaluation of the tissues forming the nasal passages revealed loss of epithelial lining and fibrous tissue replacement of surrounding bone. A direct correlation of pathologic changes could not be associated with the amount of radiation received, but there seemed to be a tendency for greater change in those dogs given higher doses and those kept alive for 6 months.

A study was designed to determine whether phenytoin (PHE) prevents the myocardial necrosis and subsequent fibrosis produced by isoproterenol (ISO). Seven groups of female rats of the Wistar strain were used. Rats in groups 1 and 5 served as controls. Rats in group 3 were injected SC with 85 mg of ISO/kg of body weight for 2 consecutive days. Rats in groups 2 and 6 received 100 mg of PHE/kg orally. Rats in groups 4 and 7 received both PHE and ISO. There were 6 to 9 rats/group. Effects of ISO and PHE were evaluated gravimetrically, histologically, and electrocardiographically. Heart weight/body weight ratios for each group receiving ISO, with or without PHE, were greater than for groups not receiving ISO (P less than 0.05). Light microscopic examination of heart sections of rats given ISO alone or ISO + PHE revealed multiple and diffuse areas of fibrosis. Fibrosis in hearts from rats receiving PHE + ISO was less severe than that in hearts from rats receiving ISO alone, but the difference was not statistically significant. Electrocardiographic changes of statistical significance were not observed in rats receiving any compound (alone or in combination), when compared with the control groups of equal age.