Selected clinical, biochemical, and electrolyte alterations in anesthetized captive tigers (Panthera tigris) and lions (Panthera leo).

A prospective study to assess changes in selected plasma biochemistry and electrolyte values, plasma insulin and aldosterone concentrations, and electrocardiography (ECG) was performed on eight female captive tigers (Panthera tigris) and three lions (Panthera leo) undergoing general anesthesia for elective laparoscopic ovariectomy. Each animal was sedated with medetomidine (18-25 microg/kg) and midazolam (0.06-0.1 mg/kg) intramuscularly, and anesthesia was induced with ketamine (1.9-3.5 mg/kg) intramuscularly and maintained with isoflurane. Venous blood samples were collected and analyzed for plasma biochemistry parameters and insulin and aldosterone concentrations. An ECG was recorded at the time of each blood sample collection. Mean plasma potassium, glucose, phosphorus, and aldosterone concentrations increased during anesthesia (P < or = 0.05). One tiger developed hyperkalemia (6.5 mmol/L) 2.5 hr after anesthetic induction. Plasma insulin concentrations were initially below the low end of the domestic cat reference interval (72-583 pmol/L), but mean insulin concentration increased (P < or = 0.05) over time compared with the baseline values. Three tigers and two lions had ECG changes that were representative of myocardial hypoxemia. Based on these results, continuous monitoring of clinical and biochemical alterations during general anesthesia in large nondomestic felids is warranted, and consideration should be given to reversal of medetomidine in these animals should significant changes in electrolytes or ECG occur.

Diagnosis and treatment of a dermal malignant melanoma in an African lion (Panthera leo).

A 13-yr-old intact male African lion (Panthera leo) presented with a 4-mo history of left maxillary lip swelling. On physical examination, a 10-cm-diameter, ulcerated, round, firm, and pigmented mass at the level of the left maxillary canine tooth was noticed. All other organ systems examined were within normal limits. Multiple biopsies of the mass were collected and fixed in 10% neutral buffered formalin. Histopathologic evaluation of the biopsies revealed a malignant dermal melanoma. Hematologic and plasma biochemical parameters were within normal reference ranges. Thoracic radiographs taken 3 days following initial presentation showed no evidence of metastasis of the tumor. Computed tomography of the skull and neck was performed to evaluate local tumor invasion and to plan for hypofractionated radiation therapy. Therapy included four weekly treatments of 8 gray external-beam hypofractionated radiation and four bimonthly immunotherapy treatments. Following this treatment regime, the tumor size was reduced by 50%, and surgical excision was performed. No major side effects associated with radiation or immunotherapy were seen. Six months after diagnosis, hematologic and plasma biochemical parameters were within normal limits, thoracic radiographs showed no evidence of metastasis, and the lion showed no clinical signs of disease. The lion will continue to receive immunotherapy every 6 mo for the rest of its life. To the authors' knowledge, this is the first report of a successful treatment of a malignant dermal melanoma with external-beam hypofractionated radiation, immunotherapy, and surgical excision in an African lion.

Comparison of first-intention healing of carbon dioxide laser, 4.0-MHz radiosurgery, and scalpel incisions in ball pythons (Python regius).

OBJECTIVE: To evaluate first-intention healing of CO(2) laser, 4.0-MHz radiowave radiosurgery (RWRS), and scalpel incisions in ball pythons (Python regius). ANIMALS: 6 healthy adult ball pythons. PROCEDURES: A skin biopsy sample was collected, and 2-cm skin incisions (4/modality) were made in each snake under anesthesia and closed with surgical staples on day 0. Incision sites were grossly evaluated and scored daily. One skin biopsy sample per incision type per snake was obtained on days 2, 7, 14, and 30. Necrotic and fibroplastic tissue was measured in histologic sections; samples were assessed and scored for total inflammation, histologic response (based on the measurement of necrotic and fibroplastic tissues and total inflammation score), and other variables. Frequency distributions of gross and histologic variables associated with wound healing were calculated. RESULTS: Gross wound scores were significantly greater (indicating greater separation of wound edges) for laser incisions than for RWRS and scalpel incisions at all evaluated time points. Necrosis was significantly greater in laser and RWRS incisions than in scalpel incision sites on days 2 and 14 and days 2 and 7, respectively; fibroplasia was significantly greater in laser than in scalpel incision sites on day 30. Histologic response scores were significantly lower for scalpel than for other incision modalities on days 2, 14, and 30. CONCLUSIONS AND CLINICAL RELEVANCE: In snakes, skin incisions made with a scalpel generally had less necrotic tissue than did CO(2) laser and RWRS incisions. Comparison of the 3 modalities on the basis of histologic response scores indicated that use of a scalpel was preferable, followed by RWRS and then laser.

Laparoscopic-assisted ovariectomy of tigers (Panthera tigris) with the use of the LigaSure device.

Laparoscopic ovariectomy was performed in seven tigers with the use of a vessel-sealing device and a three-port technique. A comparison group of seven tigers that underwent traditional ovariohysterectomy was assembled with the use of a medical records search. Mean operative times for laparoscopic ovariectomy were compared to standard ovariohysterectomy, and mean combined laparoscopic incision length compared to standard ovariohysterectomy incision lengths. Significance was set at P < or = 0.05. Mean surgical time for laparoscopic ovariectomy (82 min, range 71-126 min) was significantly shorter than standard ovariohysterectomy surgical time (129 min, range 80-165 min, P = 0.007). Mean combined laparoscopic incision length (8.07 cm, range 3.80-9.50 cm) was significantly shorter than the mean incision length for standard ovariohysterectomy (13.57 cm, range 12.00-20.00 cm, P = 0.009). There were no clinically important complications observed in either group. Laparoscopic ovariectomy has a significantly shorter surgical time and combined incision length compared to standard ovariohysterectomy in tigers, and appears to be a safe and rapid sterilization method for tigers. Equipment cost and the necessity for advanced training may limit its use in some institutions. Further prospective evaluation is warranted to determine whether it is associated with decreased morbidity, mortality, or cost.

Use of nitinol stents for end-stage tracheal collapse in dogs.

OBJECTIVE: To report bronchoscopic placement of nitinol stents (Vet Stent-Trachea®) for improvement of end-stage clinical signs in dogs with tracheal collapse. STUDY DESIGN: Case series. SAMPLE POPULATION: Dogs (n = 18). METHODS: Medical records (January 1, 2004-October 31, 2008) were searched for dogs with a diagnosis of tracheal collapse; 18 dogs met inclusion criteria. Tracheal diameter was compared before and after stent deployment. Stent dimensions were compared after stent deployment and at radiographic follow-up. RESULTS: There was a significant difference in the minimum tracheal diameter when initial and post deployment tracheal diameters were compared (P = .003). Stent length was significantly shorter at follow-up when compared to post deployment measurements (P = .004). Owner assessment of outcome was available for all dogs with 11.1% mortality within 60 days. Complications were documented in 9 dogs. CONCLUSIONS: Use of a nitinol stent (Vet Stent-Trachea®) in dogs with end-stage tracheal collapse is associated with a fair to good outcome despite significant temporal stent fore shortening after bronchoscopic placement.

Magnetic resonance imaging of canine mast cell tumors.

Mast cell tumors (MCT) are the most common cutaneous tumors in dogs. Our purpose was to describe the magnetic resonance (MR) imaging characteristics of cutaneous MCT and to identify imaging characteristics that allow differentiation of metastatic from normal lymph nodes. Eight dogs with a total of nineMCT were imaged as were their presumed draining and associated contralateral lymph nodes. The signal intensity of tumors and lymph nodes was compared to adjacent musculature. On T2-W images, 7/9 MCT were hyperintense to muscle and 2/9 were isointense. On T1-W images, 8/9 MCT were isointense and 1/9 were mildly hypointense. All tumors were strongly contrast enhancing; 5/9 were homogeneous and 4/9 heterogeneous in their enhancement patterns. Six lymph node pairs were included in the evaluation (five sentinel lymph nodes with metastases, one without, and six contralateral lymph nodes). Metastatic lymph nodes were significantly larger than their contralateral lymph nodes (P = 0.039). All lymph nodes were isointense on T1-W images and hyperintense on T2-W images. 5/5 metastatic and 2/7 normal lymph nodes were heterogeneously T2-hyperintense. All lymph nodes were moderately to strongly contrast enhancing. 4/5 metastatic and 2/7 normal lymph nodes had heterogeneous enhancement patterns. While heterogeneity was more common in metastatic than in normal lymph nodes, this difference was not significant (P = 0.058 for T2-W images; P = 0.234 for postcontrast images). MR imaging may be useful in the presurgical evaluation and clinical staging of cutaneous MCT.

Characterization of multiple acquired portosystemic shunts using transplenic portal scintigraphy.

We describe the scintigraphic patterns observed in 14 patients with confirmed multiple portosystemic shunts imaged via transplenic portal scintigraphy. Parameters evaluated included presence of multiple anomalous vessels, presence of hepatofugal flow caudal to spleen, and/or to cranial margin of the kidneys, slow absorption resulting in longer spleen to heart transit time, and presence of biphasic or fragmented bolus. Twenty-eight additional patients, 14 with a confirmed single portocaval and 14 with a portoazygos shunt, were used for comparison. Nine of 14 (64.3%) patients with multiple shunts had multiple vessels, five (35.7%) had a biphasic bolus, 13 (92.9%) had hepatofugal flow caudal to the cranial margin of the kidneys. In all single portocaval shunts, a single anomalous vessel was identified. None had hepatofugal flow caudal to the border of the kidneys. Among portoazygos shunts, 4/14 (28.6%) had flow caudal to the injection site. Six portoazygos and one portocaval shunts had biphasic bolus. Median transit time from spleen to heart was significantly longer (1.9 s) in patients with multiple shunts than in patients with a portocaval shunt (1.0 s), but not in patients with a portoazygos shunt (1.3 s). Although a distinct plexus of anomalous vessels is not detected in all patients with multiple shunts imaged using transplenic portal scintigraphy, findings of hepatofugal flow caudal to the margin of the kidneys, and longer transit time compared with single portocaval shunts were characteristic. Flow caudal to the splenic injection site but cranial to the kidneys and biphasic bolus can also be seen with a single congenital shunt.

Self-expanding nitinol stents for the treatment of tracheal collapse in dogs: 12 cases (2001-2004).

OBJECTIVE: To evaluate long-term outcome following nitinol stent placement in dogs with tracheal collapse. DESIGN: Retrospective case series. ANIMALS: 12 client-owned dogs with endoscopically diagnosed tracheal collapse refractory to medical management. PROCEDURES: Medical records were reviewed for 12 dogs in which 1 or more self-expanding nitinol stents were placed for the treatment of endoscopically diagnosed tracheal collapse. A total of 17 stents were placed. RESULTS: Survival times after stent placement ranged from 1 to 48 months. Three of 12 dogs died within 6 months after stent placement. Nine dogs survived > 1 year after stent placement, and 7 dogs survived > 2 years. Of the deceased dogs, 5 of 9 succumbed to tracheal disease. Other causes of death included congestive heart failure, cerebral neoplasia, cerebrovascular accident, and renal failure. Material failure (stent fracture) was a common complication (5/12 dogs). Other complications reported included excessive granulation tissue within the stent lumen, tracheitis, and pneumonia. CONCLUSIONS AND CLINICAL RELEVANCE: Placement of an intraluminal stent with self-expanding nitinol stents was a successful palliative treatment for tracheal collapse in dogs that did not respond to medical management. Disease progression is inevitable, but substantial improvement in respiratory function may be achieved for a period of months to years.

Comparison of 99mTcO4(-) trans-splenic portal scintigraphy with per-rectal portal scintigraphy for diagnosis of portosystemic shunts in dogs.

OBJECTIVE: To evaluate trans-splenic portal scintigraphy (TSPS) and per-rectal portal scintigraphy (PRPS) for diagnosis of congenital portosystemic shunts (CPSS) in dogs, and compare these results with surgical findings. STUDY DESIGN: Prospective, randomized cross over clinical trial. ANIMALS: Dogs (n=42) with suspected CPSS. METHODS: Dogs had TSPS and PRPS 48 hours apart; quantity of radionuclide administered was recorded. Three independent, blinded reviewers evaluated each scintigraphic study for study quality, shunt presence, number, and location of shunt termination (caudal vena cava, azygos vein). All dogs had exploratory celiotomy. Negative scintigraphic findings were confirmed with intraoperative mesenteric portography. Ameroid constrictors were placed on all extrahepatic CPSS, and hepatic biopsies were obtained. RESULTS: TSPS was 100% sensitive and specific for diagnosis of CPSS and significantly (P<.05) more likely than PRPS to detect shunt number and termination. Interpretation was consistent between observers, and TSPS required significantly less radionuclide than PRPS. CONCLUSION: TSPS was as sensitive as PRPS for detection of shunting vessels, and consistently yielded studies of higher quality, allowing detection of shunt number and location with consistent interpretation among radiologists. CLINICAL RELEVANCE: TSPS provides information about shunt number and location, which allows improved surgical planning. Because it requires significantly less radionuclide, TSPS improves safety, allows for more comprehensive patient care, and earlier surgical intervention.