Male Castrated Cat Research Articles

Pharmacokinetics of dexmedetomidine during administration of vatinoxan in male neutered cats anesthetized with isoflurane

Dexmedetomidine is an alpha-2 adrenoceptor agonist, and vatinoxan is an alpha-2 antagonist believed to poorly cross the blood-brain barrier in cats. Dexmedetomidine-vatinoxan combinations are of interest in anesthetized cats because the anesthetic sparing effect of dexmedetomidine may be preserved while vatinoxan attenuates the adverse cardiovascular effects of dexmedetomidine. The aim of this study was to characterize the pharmacokinetics of dexmedetomidine in cats during administration of isoflurane and vatinoxan. Six healthy adult male castrated cats were anesthetized with isoflurane in oxygen. Vatinoxan was administered using a target-controlled infusion system intended to maintain a plasma concentration of 4 µg/ml. Dexmedetomidine, 35 µg/kg was administered intravenously over 5 min. Plasma dexmedetomidine and vatinoxan concentrations were measured at selected time points ranging from prior to 8 hr after dexmedetomidine administration using liquid chromatography/tandem mass spectrometry. Compartment models were fitted to the time-concentration data using nonlinear mixed-effect modeling. A three-compartment model best fitted the data. Typical value (% interindividual variability) for the three-compartment volumes (ml/kg), the metabolic clearance and the two intercompartment distribution clearances (ml min-1 kg-1 ) were 168 (259), 318 (35), 1,425 (18), 12.4 (31), 39.1 (18), and 29.6 (17), respectively. Mean ± standard deviation plasma vatinoxan concentration was 2.6 ± 0.6 µg/ml.

Associations between increased body condition score, bodyweight, age and breed with urethral obstruction in male castrated cats

Identifying potential risk factors for urethral obstruction in male cats may help in disease prevention. The aims of this study were to assess whether breed, pedigree status, age, bodyweight and body condition score (BCS) are risk factors for urethral obstruction in castrated male cats using a primary care population. Within this, a specific question was whether any increase in rate of urethral obstruction in male cats due to excess body condition is because of higher bodyweight. A retrospective hospital-based matched case-control study was performed using 195 cases of urethral obstruction in castrated male cats and 195 control consultations for cats presenting to a feline-only first opinion veterinary practice in Brisbane, Australia.The incidence rate of urethral obstruction did not vary significantly with bodyweight but increased with BCS (incidence rate ratio 1.6; 95% CI 1.2–2.1; P<0.001). The effect of BCS was not due to high BCS cats having higher bodyweights. The incidence was lower in Burmese cats compared to Domestic shorthair cats (incidence rate ratio 0.1; 95% CI 0.0–0.4; P=0.001), and higher in non-pedigree cats compared to pedigree cats (incidence rate ratio 2.8; 95% CI 1.7–4.6; P<0.001). Incidence rate ratios increased with age to 2 to 4years (the ages with highest incidences) then progressively declined with each additional year of age. Further research is needed to define why there is a positive association between BCS and rate of urethral obstruction. In the interim, clinicians should encourage owners of castrated male pet cats to ensure their cat’s BCS is not high.

Effect of intraoperative positioning on postoperative neurological status in cats after perineal urethrostomy.

The aim of this study was to evaluate and quantify the changes in neurological status in cats after perineal urethrostomy performed in dorsal and ventral recumbency. This was a prospective, randomised study. Twenty male castrated cats with feline lower urinary tract disease presented for perineal urethrostomy were enrolled in this study. Surgery was performed in either dorsal recumbency (group A) or ventral recumbency (group B). Motor response of patellar tendon, gastrocnemius muscle, pelvic limb withdrawal and perineal reflexes, as well as the presence of spinal pain in the lumbosacral region, motor function of the tail and faecal continence, were examined before surgery, and 24 h and 14 days after surgery. The animals had a mean weight of 5.07 ± 1.08 kg, with a mean age of 6.12 ± 1.85 years. Weight and age were not significantly different between groups A and B (both P = 0.897). All tested parameters of the neurological examination performed prior to surgery were considered normal in both groups (P = 1). The comparison between neurological examinations (perineal reflex and spinal pain) before and 24 h after surgery revealed a significantly decreased briskness of the perineal reflex and an increased occurrence of spinal pain 24 h after surgery (P = 0.043 and P = 0.031, respectively). However, the changes of aforementioned parameters were statistically insignificant (P = 0.249 and P = 0.141) between groups A and B. The other parameters (patellar tendon, pelvic limb withdrawal and gastrocnemius muscle reflexes, motor function of the tail and faecal continence) were statistically insignificant (P = 1) before surgery and 24 h after surgery, as well as between groups A and B 24 h after surgery. Results of all tested parameters were statistically insignificant (P = 1) before surgery and 14 days after surgery, as well as between groups A and B 14 days after surgery. The briskness of the perineal reflex was significantly decreased and the occurrence of spinal pain significantly increased 24 h after surgery. A parallel with a low-grade positioning-dependent nerve injury as described in human medicine may be drawn. However, no positioning method was proven to be superior to the other.

Enteroplication in cats with intussusception: a retrospective study (2001-2016).

The aim of this study was to report complications, as well as short- and long-term clinical outcomes of cats suffering from surgically reduced intussusception with and without enteroplication. Medical records of cats presented at our institution with intussusception between 2001 and 2016 were reviewed. The following data were retrieved: signalment; history; physical examination; diagnostic imaging, surgical and histological findings; and outcomes. Animals were grouped as with or without enteroplication. Duration of surgery, survival, complication and recurrence rates, duration of hospitalisation, and short- and long-term outcomes were compared. Cats with intussusception presented with unspecific type and duration of clinical signs. Male or male castrated cats and Maine Coons were over-represented in both groups. Enteroplication was performed in 48% (10/21) of the cats. Cats in the enteroplication group were significantly younger than those in the non-enteroplication group ( P = 0.023). Duration of surgery, time of hospitalisation, complication rate and outcomes did not differ between the two groups. Two complications in the short term and one complication in the long term were possibly associated with enteroplication. A recurrence of intussusception was seen in 2/17 cats approximately 12 months after initial surgery, both previously treated with enteroplication. Although the number of cases was limited, our results suggest that enteroplication should be cautiously performed in cats with intussusception as it may be associated with major complications in the short and long term, and its efficacy remains unclear. Based on this study, the need for enteroplication in cats following a correction of intussusception could be questioned.

Pharmacokinetics of dexmedetomidine, MK-467 and their combination following intramuscular administration in male cats

ObjectiveTo characterize the pharmacokinetics of dexmedetomidine, MK-467 and their combination following intramuscular (IM) administration to cats. Study designProspective randomized crossover experimental study. AnimalsA total of eight healthy adult male castrated cats aged 1–2 years. MethodsCats were administered dexmedetomidine (25 μg kg–1) IM (treatment D25IM) or intravenously (IV; treatment D25IV); MK-467 (600 μg kg–1) IM (treatment MK600IM) or IV (treatment MK600IV); or dexmedetomidine (25 μg kg–1) IM with 300, 600 or 1200 μg kg–1 MK-467 IM (treatments D25MK300IM, D25MK600IM and D25MK1200IM). D25MK600IM was the only combination treatment analyzed. Blood samples were obtained prior to drug administration and at various times for 5 hours (D25IV) or 8 hours (all other treatments) thereafter. Plasma dexmedetomidine and MK-467 concentrations were measured using liquid chromatography/mass spectrometry. Compartment models were fitted to the time–concentration data. ResultsA one-compartment model best fitted the time–plasma dexmedetomidine concentration data in cats administered D25IM, and the time–plasma MK-467 concentration data in cats administered MK600IM and D25MK600IM. A two-compartment model best fitted the time–plasma dexmedetomidine concentration data in cats administered D25IV and D25MK600IM, and the time–plasma MK-467 concentration data in cats administered MK600IV. Median (range) area under the time–concentration curve, absorption rate half-life, maximum concentration, time to maximum concentration and terminal half-life for dexmedetomidine in D25IM and D25MK600IM were 1129 (792–1890) and 924 (596–1649) ng minute mL–1, 4.4 (0.4–15.7) and 2.3 (0.2–8.0) minutes, 10.2 (4.8–16.9) and 17.8 (15.8–73.5) ng mL–1, 17.8 (2.6–44.9) and 5.2 (1.2–15.1) minutes and 62 (52–139) and 50 (31–125) minutes, respectively. Rate of absorption but not systemic exposure was significantly influenced by treatment. No significant differences were observed in MK-467 pharmacokinetic parameters in MK600IM and D25MK600IM. Conclusions and clinical relevanceMK-467 significantly influenced the disposition of dexmedetomidine, whereas dexmedetomidine did not significantly affect the disposition of MK-467 when the drugs were coadministered IM.

Minimal change glomerulopathy in a cat

A 6-year-old domestic shorthair male castrated cat was evaluated for sudden onset of vomiting and anorexia. A diagnosis of hypereosinophilic syndrome (HES) was made, and the cat was treated with imatinib mesylate. The cat had an initial clinical improvement with the normalization of the peripheral eosinophil count. After approximately 8 weeks of treatment, lethargy and anorexia recurred despite the normal eosinophil count and a significant proteinuric nephropathy was identified. Treatment with imatinib was discontinued. Ultrasound guided renal biopsies exhibited histologic, ultrastructural, and immunostaining changes indicative of a minimal change glomerulopathy (MCG) which has not previously been reported in the literature in a cat. The proteinuria and HES initially improved while the cat was treated with more traditional medications; however, both the problems persisted for 30 months that the cat was followed subsequently. Previous studies demonstrating the safety and efficacy of imatinib in cats do not report any glomerular injury or significant adverse drug reactions, and the exact cause of this cat's proteinuric nephropathy is uncertain. Nonetheless, the possibility of an adverse drug reaction causing proteinuria should be considered when initiating treatment with imatinib in a cat.

Ganglioneuroblastoma in a cat: A rare neoplasm treated with electrochemotherapy

An 8-year-old male castrated cat was referred for sudden onset of lameness. Physical examination revealed a 1 × 2 × 1 cm mass originating from a footpad of the right hind leg. A diagnosis of ganglioneuroblastoma was suggested by the tumour appearance following histopathological staining with haematoxylin and eosin and haematoxylin/van Gieson. Immunohistochemical staining for glial fibrillary acidic protein (GFAP), vimentin, neuron-specific enolase (NSE), neurofilament and S100 further confirmed the diagnosis. The staging process did not indicate metastatic spread. The cat was treated with three sessions of electrochemotherapy (ECT) 1 week apart, following local injection of bleomycin. The tumour had completely regressed within 1 week of the third ECT application and remained in remission for 402 days at which time a small recurrence was noted. The animal was given a further session of ECT using intra-lesional cisplatin and again went into remission. It remained tumour free at 450 days. Electrochemotherapy is considered a safe and effective treatment for localised neoplasms of cats and dogs and warrants further investigation.

Palliative use of a stent for colonic obstruction caused by adenocarcinoma in two cats

CASE DESCRIPTION-Two adult male castrated cats were evaluated because of a history of constipation, tenesmus, or intermittent vomiting. CLINICAL FINDINGS-Radiography and ultrasonography revealed luminal narrowing in the colon of 1 cat and a colonic mass in the other. A histopathologic diagnosis of colonic adenocarcinoma was made in both cats. TREATMENT AND OUTCOME-Under fluoroscopic guidance, a self-expanding metallic stent was advanced over a wire and across the area of colonic stenosis and deployed. One cat had progressive weight loss but maintained a normal appetite, energy, and a high quality of life. Fecal continence was maintained, and tenesmus was rarely observed. The cat was euthanized because of tumor metastasis 274 days after the colonic stent was placed. The other cat retained fecal continence, and the owners reported subjective improvement in the severity of tenesmus, compared with that prior to stent placement. The cat was euthanized 19 days after stent placement because of perceived decreased quality of life. CLINICAL RELEVANCE-The use of self-expanding metallic stents for alleviation of colonic obstruction secondary to adenocarcinoma in cats appears to be effective. This technique provides a simple, quick, nonsurgical option for palliation in cats with advanced metastatic or systemic disease in which surgical resection may not be possible or warranted.

Adenomatous polyps of the duodenum in cats: 18 cases (1985-1990)

Summary: Medical records were reviewed for 18 cats with adenomatous polyps of the proximal portion of the duodenum. Cats of Asian ancestry were over represented (8/18), and male castrated cats were common (15/18). The median age was 11.8 years. Common clinical signs were acute and chronic vomiting and hematemesis. Nine cats were anemic. Contrast radiography was performed in 12 cats, and a mass of the proximal portion of the duodenum was identified in 10 cats. Endoscopy was used to confirm existence of the mass in 3 cats. Complete excision of the duodenal mass was performed in 17 cats. One cat died before abdominal exploratory surgery, and a duodenal adenomatous polyp was identified at necropsy. Fifteen cats survived the immediate postoperative period, with 13 of 15 having complete resolution of clinical signs. Five cats had concurrent disease, which caused 4 of them to die between 3 and 26 months after surgery. Redevelopment of adenomatous polyps was not detected in any cat during the follow-up period of 1 to 49 months. Results of the study indicated that benign, adenomatous polyps of the duodenum in cats can be safely excised and that the prognosis for return to normal function is excellent.