Diagnosis and treatment of concurrent dermal malignant melanoma and melanocytomas in a pygmy hippopotamus (Choeropsis liberiensis).

BACKGROUND: Dermal melanocytic neoplasms are common in some even-toed ungulates (Artiodactyla), yet this entity has not been reported in the pygmy hippopotamus to date. Concurrent occurrence of multiple benign and malignant melanocytic neoplasms is unusual. Malignant transformation occurs in a small percentage of benign melanocytic tumours in people but this phenomenon has not been well documented in animals. OBJECTIVES: To report the diagnosis and treatment of concurrent dermal melanocytomas and malignant melanomas in a pygmy hippopotamus. ANIMALS: A 36-year-old intact male pygmy hippopotamus, part of a zoological collection, housed with a 10-year-old female of the same species, presented with multiple raised and pigmented skin masses. METHODS: Initial impression smears of one ulcerated lesion were consistent with inflammation; subsequent histopathological findings from a skin biopsy revealed an underlying malignant melanoma. The animal was anaesthetised, ultrasonographic imaging of the local lymph nodes indicated no local involvement and all skin lesions were removed. Recovery from anaesthesia was unremarkable, skin healing was within normal limits for the species. There was no sign of recurrence 34 months post-surgery. RESULTS: A diagnosis of malignant melanomas and concurrent melanocytomas was made on histopathological evaluation. CONCLUSION AND CLINICAL IMPORTANCE: To the best of the authors' knowledge, this is the first reported case of melanocytic neoplasia in the pygmy hippopotamus. The occurrence of both benign and malignant melanocytic skin tumours should be considered in this species.

Characterization of primary pulmonary adenosquamous carcinoma-associated pleural effusion.

A 10-year-old, female spayed Shih Tzu was presented due to weight loss, increased respiratory effort and lethargy, determined to be secondary to a congenital para-esophageal diaphragmatic defect with partial herniation of the stomach and spleen. Four days following reduction surgery of the displaced abdominal organs thoracic effusion developed. Thoracic fluid evaluation revealed a cell-rich, protein-poor modified transudate with neutrophils, reactive mesothelial cells, and atypical epitheloid cells which occasionally appeared to be keratinizing, consistent with neoplastic exfoliation. Thoracic effusion recurred 2 days later, with similar characteristics as the initial sample. Computed tomography (CT) indicated consolidation and displacement of the right middle and accessory lung lobes. Exploratory thoracic surgery demonstrated a thickened, hyperemic right middle lung lobe, and thickened pericardial diaphragmatic ligament. Histologic evaluation of these tissues identified a primary pulmonary adenosquamous carcinoma with intravascular and pleural invasion. Based on these cytologic, histologic, and clinical findings, we conclude that primary pulmonary carcinomas may involve superficial thoracic structures and exfoliate into a thoracic effusion.

Rapid vascular uptake of contrast during a retrograde urethro-cystogram in a cat with chronic lower urinary tract disease.

CASE SUMMARY: A 9-year male neutered domestic longhair cat was referred to our hospital for investigation of recurrent urinary tract obstruction. The clinical signs had started 12 months earlier and the cat had been catheterised on multiple occasions. Clinical examination and abdominal ultrasound of the abdomen was unremarkable but examination of the penis revealed it to be prolapsed and extremely erythematous and friable. A retrograde contrast urethrocystogram was performed, showing extravasation of the contrast medium and establishing the presence of partial leakage or a tear of the urethra. In subsequent radiographs, the contrast was seen being rapidly absorbed into the pelvic and systemic vasculature via the penile veins, internal and external pudendal veins, internal and external iliac veins, and, ultimately, the caudal vena cava. Later, the contrast medium was seen within the renal pelves. Retrograde urethrocystography revealed stenosis and irregularities of the caudal urethral mucosa consistent with strictures. A routine perineal urethrostomy was performed and the cat recovered well. CONCLUSIONS AND RELEVANCE: Rapid vascular absorption of extravasated contrast medium has not been reported before. In this case, the increased blood supply to the distal urethra and penis is likely secondary to (chronic) inflammation, as demonstrated by the urethral strictures and the friable, oedematous nature of the penis. Whether the inflammation was caused by chronic obstruction or repeated iatrogenic trauma, or a combination of these factors, will remain debatable. Nonetheless, this case demonstrates that when a retrograde contrast urethrocystogram is considered, it is imperative that a contrast medium (or other intraurethral medication such as local anaesthesia) is chosen that is safe for intravascular use. Equally, an absolute aseptic technique is essential considering the potential for contaminants to be absorbed quite rapidly into the systemic circulation. Multiple catheterisations should be avoided when there is chronic inflammation, and alternative options should be considered when chronic disease is suspected.

Evaluation of steam penetration and sterilization of natural latex wraps.

OBJECTIVE: To evaluate the efficacy of steam and ethylene oxide (EtO) sterilization of Vetrap™ bandages. STUDY DESIGN: Prospective experimental study. SAMPLE POPULATION: Vetrap™ bandages (n = 70; 35 as supplied by the manufacturer, 35 unwound and tightly rewound). METHODS: Vetrap™ bandage rolls (n = 60) marked with a 1 cm square were inoculated with 0.1 mL Geobacillus stearothermophilus spores, packaged in a pouch together with independent sterilization indicators and assigned into 3 sub-groups for sterilizer type: dynamic air removal, gravity displacement, and bench-top pre-vacuum and further sub-divided into 2 sterilization temperatures. Vetrap™ bandages rolls (n = 10) were inoculated with 0.1 mL Bacillus atrophaeus spores in the same manner and underwent EtO sterilization. After sterilization, the 1 cm marked square was aseptically resected to the level of the cardboard tube and enriched in a flask containing 10 mL tryptic soy broth for 24 hours at 60°C for G. stearothermophilus and 37°C for B. atrophaeus. Aliquots were subsequently plated on a Petri dish of tryptic soy agar and incubated at 60°C for G. stearothermophilus and 37°C for B. atrophaeus for 24 hours. Samples were scored positive if colonies of indicator organism were present on the nutrient agar after 24 hours. RESULTS: Three Vetrap™ bandages yielded post-sterilization growth of G. stearothermophilus: 2 from the dynamic air removal sterilizer at 134°C for 3.5 minutes, and 1 from the bench-top pre-vacuum sterilizer at 121°C for 15 minutes. After EtO sterilization, no positive samples were detected. CONCLUSIONS: Steam sterilization may be incomplete for Vetrap™ bandages whereas EtO showed complete destruction of resistant bacterial spores.

Ischaemic distal limb necrosis and Klebsiella pneumoniae infection associated with arterial catheterisation in a cat.

This case report describes dorsal pedal arterial thrombosis and infection with Klebsiella pneumoniae subsequent to arterial catheter placement in a cat. The complication led to avascular necrosis of the metatarsal and pedal soft tissue. The catheter was placed for blood pressure monitoring during surgery for correction of a peritoneopericardial diaphragmatic hernia. The exact mechanism of thrombosis was unclear. Amputation of the limb was required and the histopathological findings are presented. This is the first report of such a complication.

Alfaxalone for total intravenous anaesthesia in dogs undergoing ovariohysterectomy: a comparison of premedication with acepromazine or dexmedetomidine.

OBJECTIVE: To describe alfaxalone total intravenous anaesthesia (TIVA) following premedication with buprenorphine and either acepromazine (ACP) or dexmedetomidine (DEX) in bitches undergoing ovariohysterectomy. STUDY DESIGN: Prospective, randomised, clinical study. ANIMALS: Thirty-eight healthy female dogs. METHODS: Following intramuscular buprenorphine (20 µg kg(-1) ) and acepromazine (0.05 mg kg(-1) ) or dexmedetomidine (approximately 10 µg kg(-1) , adjusted for body surface area), anaesthesia was induced and maintained with intravenous alfaxalone. Oxygen was administered via a suitable anaesthetic circuit. Alfaxalone infusion rate (initially 0.07 mg kg(-1) minute(-1) ) was adjusted to maintain adequate anaesthetic depth based on clinical assessment. Alfaxalone boluses were given if required. Ventilation was assisted if necessary. Alfaxalone dose and physiologic parameters were recorded every 5 minutes. Depth of sedation after premedication, induction quality and recovery duration and quality were scored. A Student's t-test, Mann-Whitney U and Chi-squared tests determined the significance of differences between groups. Data are presented as mean ± SD or median (range). Significance was defined as p < 0.05. RESULTS: There were no differences between groups in demographics; induction quality; induction (1.5 ± 0.57 mg kg(-1) ) and total bolus doses [1.2 (0 - 6.3) mg kg(-1) ] of alfaxalone; anaesthesia duration (131 ± 18 minutes); or time to extubation [16.6 (3-50) minutes]. DEX dogs were more sedated than ACP dogs. Alfaxalone infusion rate was significantly lower in DEX [0.08 (0.06-0.19) mg kg(-1) minute(-1) ] than ACP dogs [0.11 (0.07-0.33) mg kg(-1) minute(-1) ]. Cardiovascular variables increased significantly during ovarian and cervical ligation and wound closure compared to baseline values in both groups. Apnoea and hypoventilation were common and not significantly different between groups. Arterial haemoglobin oxygen saturation remained above 95% in all animals. Recovery quality scores were significantly poorer for DEX than for ACP dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Alfaxalone TIVA is an effective anaesthetic for surgical procedures but, in the protocol of this study, causes respiratory depression at infusion rates required for surgery.

MRI findings of a middle ear cholesteatoma in a dog.

This article describes the MRI features of a middle ear cholesteatoma in an 8 yr old flat-coated retriever. Physical examination revealed pain on opening the jaw, and otoscopic examination showed tympanic membrane rupture associated with hyperplastic tissue at the entrance of the middle ear. Standard MRI sequences allowed for the identification of a severely expanded bulla containing material that was isointense to brain tissue on T1-weighted images and of mixed intensity on T2-weighted and fluid-attenuated inversion recovery sequences. No postcontrast enhancement of the content was present, but the lining of the bulla was partially enhanced. The images allowed evaluation of the surgical margins and the secondary changes due to the expansion of the mass. Surgery was performed and histopathology confirmed the presumptive diagnosis of cholesteatoma. In the present case, MRI appeared to serve as a good alternative to computed tomography for the diagnosis of cholesteatoma.

Canine sacroiliac luxation: anatomic study of the craniocaudal articular surface angulation of the sacrum to define a safe corridor in the dorsal plane for placement of screws used for fixation in lag fashion.

OBJECTIVE: To define a safe corridor in the dorsal plane relative to the articular surface for placement of a single screw in lag fashion to achieve stabilization of sacroiliac luxation in the dog. STUDY DESIGN: Cadaveric study. METHODS: Dorsoventral radiographs of denuded canine sacra (n=49) were taken to determine the safe corridor in the craniocaudal plane, and the maximum, optimum and minimum angles were calculated that would allow a screw inserted in lag fashion to engage at least 60% of the width of the sacral body without cranial or caudal penetration through the bone. RESULTS: The mean safe corridor in the dorsal plane is ∼24° wide. Mean craniocaudal minimum, optimum and maximum drill angles from the drill start point were 88°, 100°, and 111° from the articular surface, respectively. No single angle will completely avoid risk of screw penetration beyond the safe corridor cranially and caudally. CONCLUSIONS: There is sufficient anatomic variation between different canine sacra that a single angle cannot be recommended for screw placement in the dorsal plane. CLINICAL RELEVANCE: A standard angle cannot be recommended for screw placement in lag fashion within the canine sacrum in the dorsal plane. Because of the narrow width of the safe corridor, preoperative measurements on radiographs are recommended and a range of angled drill guides may be useful to decrease surgeon margin of error.