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- Author or Editor: Clarence A. Rawlings x
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SUMMARY
Postadulticide pulmonary hypertension mechanisms and treatment with antihistamines and supplemental oxygen were studied in eight dogs with heartworm disease. To ensure severe postadulticide thromboembolism, additional heartworms (either 20 or 40 into 4 dogs each) were transplanted into naturally infected dogs before thiacetarsamide treatment. During pentobarbital anesthesia, 2 pulmonary hemodynamic studies were conducted on each dog with a sequence of baseline, hypoxia with FlO2 = 10%, hyperoxia with FlO2 = 100%, a second baseline, treatment with either diphenhydramine (D) or cimetidine (C), and another hypoxia.
All dogs were pulmonary hypertensive, with each dog having a mean pulmonary arterial pressure (PPA) > 20 mm of Hg. Mean PPA increased from baseline conditions (25.0 ± 4.5 SD for D and 24.3 ± 4.4 for C) to hypoxia (28.5 ± 4.7 for D and 28.4 ± 3.7 for C), and decreased during hyperoxia (16.9 ± 3.0 for D and 17.4 ± 3.0 for C), respectively. Neither antihistamine reduced PPA at normoxia. The degree of pulmonary hypertension when breathing room air increased even more during hypoxia, and this increase was not attenuated by either antihistamine. Histamine did not appear to mediate pulmonary hypertension during postadulticide thromboembolism, nor to modify the hypoxia-mediated pulmonary hypertension at this disease stage. Because baseline PO2 was low (66.6 ± 11.7 mm of Hg for D and 69.4 ± 14.2 for C) and because PPA decreased during administration of oxygen, the pulmonary hypertension was mostly hypoxia-induced. In addition to the arterial lesions, much of the pulmonary hypertensive mechanism was an active and reversible vasoconstriction in response to hypoxia caused by the secondary lung disease. Supplemental oxygen to dogs with pulmonary hypertension could reduce PPA and right ventricular afterload. This study supports the use of oxygen, but not antihistamine drugs, in the treatment of postadulticide heartworm disease in dogs that are hypoxic, with signs of congestive heart failure or dyspnea.
Abstract
Objective—To compare effects of medetomidine and xylazine hydrochloride on results of cystometry and micturition reflexes in healthy dogs and results of urethral pressure profilometry (UPP) in sedated and conscious dogs.
Animals—20 dogs.
Procedures—Urodynamic testing was performed 6 times in each dog (3 times after administration of xylazine [1 mg/kg of body weight, IV] and 3 times after administration of medetomidine (30 µg/kg, IM). Before each episode of sedation, UPP was performed. Heart and respiratory rates and indirect blood pressures were recorded prior to and 5, 10, 20, and 30 minutes after injection of sedative. Cystometry measurements included threshold volume, threshold pressure, and tonus limb. The UPP measurements included maximal urethral closure pressure (MUCP), functional profile length, and, in male dogs, plateau pressure.
Results—Mean MUCP was decreased markedly in xylazine- and medetomidine-sedated dogs. Xylazine and medetomidine also decreased plateau pressure in male dogs. The MUCP measurements were consistent among days for conscious and xylazine-sedated dogs but were inconsistent for medetomidinesedated female dogs. The proportion of valid cystometry measurements was greater for xylazine (39 of 60) than for medetomidine (27 of 60). Cystometry was considered invalid when bladder pressure reached 30 cm H2O without initiation of a micturition reflex.
Conclusions and Clinical Relevance—Medetomi dine and xylazine have similar effects on measurement of UPP and cystometry. Medetomidine was less consistent among days for UPP in female dogs and produced fewer valid cystometry tests, compared with xylazine. For urodynamic evaluations, medetomidine administered IM cannot be substituted for xylazine administered IV. (Am J Vet Res 2001;62:167–170)
Abstract
Objective—To evaluate efficacy and safety of using an electrothermal, feedback-controlled, bipolar sealing device (BSD) for resection of the elongated portion of the soft palate in brachycephalic dogs with upper airway obstruction.
Design—Uncontrolled clinical trial.
Animals—24 brachycephalic dogs with airway obstruction and elongated soft palate.
Procedures—In all dogs, the excess portion of the soft palate was resected with a BSD. A score for severity of clinical signs of respiratory tract obstruction was assigned before surgery, during the first 24 hours after surgery, and at the time of final follow-up 12 to 23 months after surgery. Potential scores ranged from 0 (no clinical signs even with moderate to vigorous activity) to 4 (agonal breathing or severe cyanosis).
Results—None of the dogs died or developed life-threatening complications after surgery. Clinical scores after surgery (mean ± SD, 0.3 ± 0.6) and at the time of final follow-up (0.9 ± 0.5) were significantly lower than preoperative scores (2.6 ± 0.8).
Conclusions and Clinical Relevance—Results indicated that a BSD can be safely used for resection of the elongated portion of the soft palate in brachycephalic dogs with upper airway obstruction.
Abstract
Objective—To determine outcome of cystoscopic-guided transection for treatment of ectopic ureters in dogs.
Design—Retrospective case series.
Animals—16 female dogs.
Procedures—Medical records of dogs that underwent cystoscopic-guided transection of the membrane separating unilateral or bilateral ectopic ureters from the urethra and bladder between May 2005 and May 2008 were reviewed. Postoperative outcome was determined by use of telephone interviews conducted 1 to 36 months after the procedure.
Results—4 dogs had complete resolution of urinary incontinence with cystoscopic-guided transection alone, an additional 5 dogs had complete resolution with a combination of cystoscopic-guided transection and phenylpropanolamine administration, and an additional 4 dogs had an improvement in urinary control, although urinary incontinence persisted. Outcome could not be assessed in the remaining 3 dogs because of collagen injections in the urethra at the time of ureteral transection (n = 2) or nephrectomy secondary to unilateral hydronephrosis (1).
Conclusions and Clinical Relevance—Results suggested that cystoscopic-guided transection may be an acceptable alternative to traditional surgical correction of ectopic ureter in dogs. Most complications associated with the cystoscopic procedure were minor and easily managed.
Abstract
Objective—To develop laparoscopic-assisted techniques for enterostomy feeding tube placement and full-thickness biopsy of the jejunum in dogs.
Animals—15 healthy dogs.
Procedure—Dogs were anesthetized, and positive pressure ventilation was provided. A trocar cannula for the laparoscope was inserted on the ventral midline caudal to the umbilicus. For enterostomy tube placement, a second trocar cannula was placed lateral to the right rectus abdominis muscle, and a Babcock forceps was used to grasp the duodenum and elevate it to the incision made for the cannula. The duodenum was sutured to the abdominal wall, and a feeding tube was inserted. For jejunal biopsy, a third trocar cannula was placed lateral to the left rectus abdominis muscle. A portion of jejunum was elevated to the incision for the second or third cannula, and a full-thickness biopsy specimen was obtained. A second specimen was obtained from another portion of jejunum, and retention sutures for the 2 biopsy sites were tied so that serosal surfaces of the biopsy sites were apposed to each other. Dogs were euthanatized 30 days after surgery.
Results—The enterostomy tube was properly positioned and functional in all 8 dogs that underwent laparoscopic-assisted enterostomy tube placement, and sufficient samples for histologic examination were obtained from all 7 dogs that underwent laparoscopic-assisted jejunal biopsy. None of the dogs had any identifiable problems after surgery.
Conclusion and Clinical Relevance—Results suggest that in dogs, laparoscopic-assisted procedures for enterostomy tube placement and jejunal biopsy are an acceptable alternative to procedures performed during a laparotomy. (Am J Vet Res 2002; 63:1313–1319)
Abstract
Objective—To characterize urodynamic function and anatomy before and after colposuspension in anesthetized female Beagles.
Animals—12 adult female Beagles.
Procedure—During general anesthesia (thiopental sodium induction and halothane maintenance), urethral pressure profiles, leak point pressure measurements with a 50-ml bladder volume, positive contrast cystograms, and retrograde vaginourethrocystograms were performed. A caudal midline laparotomy was used to perform colposuspension. Urodynamic and radiographic studies were repeated after surgery.
Results—Leak point pressures were increased (120 to 168.9 cm H2O), and maximum urethral closure pressures decreased (43.7 to 19.3 cm H2O ) after colposuspension. The urethra and bladder were moved cranially; the external urethral orifice was positioned closer to the pelvic cavity, and the neck of the bladder was positioned more cranially into the abdomen. Length of the urethra, as measured by use of vaginourethrocystograms, was increased by 3%. As measured by use of urethral pressure profiles, total profile length was increased by 19.9%, and functional profile length was increased by 19.2%.
Conclusions and Clinical Relevance—Increased leak-point pressure correlated with the expected clinical improvement attributable to colposuspension. Increased exposure of the urethra to abdominal and pelvic cavity pressures may be the mechanism by which incontinent dogs become continent after colposuspension. Results of the leak-point pressure test may correlate with clinical behavior before and after colposuspension for treatment of incontinence. (Am J Vet Res 2000;61:1353–1357)
Abstract
Objective—To determine long-term outcome associated with laparoscopic-assisted gastropexy in prevention of gastric dilatation-volvulus (GDV) in susceptible dogs and to evaluate use of laparoscopy to correct GDV.
Design—Prospective study.
Animals—25 client-owned large-breed dogs.
Procedure—23 dogs susceptible to GDV were referred as candidates for elective gastropexy. These dogs had a history of treatment for gastric dilatation, clinical signs of gastric dilatation, or family members with gastric dilatation. Laparoscopic-assisted gastropexy was performed. One year after surgery, abdominal ultrasonography was performed to evaluate the attachment of the stomach to the abdominal wall. Two dogs with GDV were also treated with laparoscopic-assisted derotation of the stomach and gastropexy.
Results—None of the dogs developed GDV during the year after gastropexy, and all 20 dogs examined ultrasonographically had an intact attachment. Another dog was euthanatized at 11.5 months for unrelated problems. Two dogs with GDV successfully underwent laparoscopic-assisted gastropexy after the stomach was repositioned.
Conclusions and Clinical Relevance—Laparoscopicassisted gastropexy resulted in a persisting attachment between the stomach and abdominal wall, an absence of GDV development, and few complications. Dogs with a high probability for development of GDV should be considered candidates for minimally invasive gastropexy. Carefully selected dogs with GDV can be treated laparoscopically. (J Am Vet Med Assoc 2002;221:1576–1581)
