James C. Steeil

DIAGNOSIS AND TREATMENT OF A PHARYNGEAL SQUAMOUS CELL CARCINOMA IN A MADAGASCAR GROUND BOA (BOA MADAGASCARIENSIS)

Abstract:  A 15-yr-old female Madagascar ground boa (Boa madagascariensis) presented with a history of anorexia, wheezing, and occasional open-mouth breathing. On oral examination, a firm, caseous mass was noted in the right caudoventral pharyngeal region, which was confirmed as a carcinoma on incisional biopsy. Advanced imaging (computed tomography and magnetic resonance imaging) was performed to evaluate local tumor invasion and to plan for palliative radiation therapy. However, following the second treatment (10 Gy), the mass had increased in size, and the snake was euthanatized. Radiation-associated vasculitis was noted within the soft tissues surrounding the mass and within muscles and the lung, which was verified on histopathology. The squamous cell carcinoma of the snake in this report was resistant to palliative radiation therapy.

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.

PHARMACOKINETICS OF CEFOVECIN (CONVENIA®) IN WHITE BAMBOO SHARKS (CHILOSCYLLIUM PLAGIOSUM) AND ATLANTIC HORSESHOE CRABS (LIMULUS POLYPHEMUS)

Abstract: Cefovecin was administered to six healthy adult white bamboo sharks (Chiloscyllium plagiosum) and six healthy adult Atlantic horseshoe crabs (Limulus polyphemus) to determine its pharmacokinetics in these species. A single dose of cefovecin at 8 mg/kg was administered subcutaneously in the epaxial region of the bamboo sharks and in the proximal articulation of the lateral leg of the horseshoe crabs. Blood and hemolymph samples were collected at various time points from bamboo sharks and Atlantic horseshoe crabs. High performance liquid chromatography was performed to determine plasma levels of cefovecin. The terminal half-life of cefovecin in Atlantic horseshoe crabs was 37.70 ± 9.04 hr and in white bamboo sharks was 2.02 ± 4.62 hr. Cefovecin concentrations were detected for 4 days in white bamboo sharks and for 14 days in Atlantic horseshoe crabs. No adverse effects associated with cefovecin administration were seen in either species.

Development of a method for the determination of cefovecin in plasma by HPLC

A simple high-performance liquid chromatography method for the determination of cefovecin in small volume plasma has been developed. Following solid-phase extraction using Oasis HLB cartridges, samples were separated by reverse-phase high-performance liquid chromatography on an XBridge C8 (3.5 µm) 4.6 × 250 mm column and quantified using ultraviolet detection at 280 nm. The mobile phase was a mixture of 10 mm ammonium acetate (pH 3.5) and acetonitrile (89:11), with a flow rate of 0.85 mL/min. The standard curve ranged from 0.1 to 200 µg/mL. Intra- and Inter-assay variability for cefovecin was <10%, and the average recovery was >90%. The lower limit of quantitation was 0.1 µg/mL. This method was successfully applied to the analysis of cefovecin samples at our institution. This is also the first fully validated method with an internal standard that does not use mass spectrometry.

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.

SELECTED CLINICAL, BIOCHEMICAL, AND ELECTROLYTE ALTERATIONS IN ANESTHETIZED CAPTIVE TIGERS (PANTHERA TIGRIS) AND LIONS (PANTHERA LEO)

Abstract: 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 μg/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 ≤ 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 ≤ 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.

Branchial Cyst With Carcinoma in an Umbrella Cockatoo (Cacatua alba)

Abstract A 16-year-old female umbrella cockatoo (Cacatua alba) was presented for a fluctuant, right-sided cervical mass that extended from the caudolateral edge of the right mandible to the coelomic inlet. Results of initial diagnostic tests were consistent with a cystic mass containing hemorrhage. Surgical exploration and removal of the mass was done, but because the hyoid apparatus was incorporated in the base of the cyst, complete surgical excision was not possible. Histopathologic results were consistent with a branchial cyst with carcinoma. Five months after surgery, the cockatoo exhibited intermittent periorbital swelling and epistaxis, and cytologic results of a fluid aspirate from the right infraorbital sinus were consistent with carcinoma. Results of magnetic resonance imaging revealed extensive abnormal T2 and short-tau inversion-recovery hyperintense tissue associated with the right side of the head and neck, infiltrating between muscle planes and extending into the right retro-orbital tissue and nasal cavity. At 7 months after surgery, the bird was severely dyspneic and was euthanatized. To our knowledge, this is the first report describing the diagnosis, management, and histologic characteristics associated with a branchial cyst with carcinoma in an animal.

CEFOVECIN (CONVENIA) FOR THE TREATMENT OF SEPTIC PERITONITIS IN A FEMALE LION (PANTHERA LEO)

An 8-yr-old intact female African lion (Panthera leo) presented with a 3-day history of lethargy, anorexia, and vomiting. Hematologic and biochemical abnormalities included a leukocytosis, 41,700/microl (4,700-15,300) with a neutrophilia (37,530/microl; 2,000-9,200) and a left shift (1,250/microl bands; 0-300), and mild hypokalemia of 2.1 mEq/L (2.8-4.8). Abdominal radiographs revealed evidence of intestinal ileus, peritonitis, and the presence of effusion. An exploratory laparotomy was performed, and septic peritonitis due to a pyometra was diagnosed. The lion was treated with an ovariohysterectomy, abdominal lavage, fluid therapy, and a subcutaneous injection of cefovecin. The lion recovered, and clinical signs associated with septic peritonitis resolved within 36 hr. It was returned to conspecifics 3 wk later. Three months postoperatively, the lion showed no residual signs of septic peritonitis.

Spontaneous proliferative and neoplastic lesions in thyroid and parathyroid glands of nondomestic felids

Based on microscopic and immunohistochemical characterization, we documented spontaneous proliferative and neoplastic lesions in the thyroid and parathyroid glands of nondomestic felids. Ten animals (4 leopards, 3 tigers, and 3 cougars), all with a previous diagnosis of thyroid neoplasia were identified from the University of Tennessee College of Veterinary Medicine database. The mean age of affected animals was 15.9 y. Twelve neoplasms were identified; 2 animals had 2 concurrent neoplasms. After immunohistochemical characterization using a panel of chromogranin A, thyroglobulin, and calcitonin, 7 of the former thyroid neoplasms were diagnosed as thyroid adenomas, 1 was diagnosed as a thyroid carcinoma, and 4 were diagnosed as parathyroid adenomas. No thyroid medullary neoplasms (C-cell tumors) were diagnosed in the current study. Most of the diagnosed neoplasms were benign (11 of 12), and metastasis was not documented in the single carcinoma. Only 2 animals were suspected to have functional neoplasms (1 thyroid adenoma and 1 parathyroid adenoma), based on associated tissue lesions or serum biochemistry. Other documented lesions in the thyroid and parathyroid glands included thyroid nodular hyperplasia (n = 7), parathyroid hyperplasia associated with chronic renal disease (n = 2), a thyroid abscess, and a branchial cyst. Parathyroid adenomas were more commonly diagnosed than expected in comparison with domestic cats. We demonstrated that an immunohistochemistry panel for thyroglobulin, calcitonin, and chromogranin A can be used to differentiate neoplasms of thyroid from parathyroid origin in nondomestic felids.

Endolymphatic Sac Carcinoma In Situ in a Tokay Gecko (Gekko gecko)

Abstract An 11-year-old female tokay gecko (Gekko gecko) was presented for bilateral asymmetric swellings of the cervical region. Baseline hematologic and plasma biochemical analyses demonstrated anemia, hypercalcemia, hyperphosphatemia, and hypoalbuminemia. Whole-body radiographs revealed a mass effect and irregular mineralization in the region of the left endolymphatic sac. Fine needle aspiration of this region revealed many elongated calcium-based crystals with pointed ends, histiocytic inflammation, and clusters of epithelial cells, consistent with hyperplasia or neoplasia of the epithelium of the endolymphatic sac. The crystals were shown to be calcium carbonate by infrared crystallography. Given the advanced state of disease and inability to completely excise the mass due to the intimate association between the meninges and endolymphatic sac, the gecko was euthanized. Gross necropsy and histopathologic evaluation revealed carcinoma in situ of the left endolymphatic sac. To our knowledge, this is the first report of neoplasia of the endolymphatic sac in a reptile.