Retrospective application of a validated algorithm for estimation of adrenal gland volume after computed tomography on 46 dogs undergoing adrenalectomy.

Canine adrenal gland volume can be predicted based on body weight and computed tomography (CT) measurements using a validated algorithm. Use of this algorithm to detect adrenal pathology, including hyperplasia, hypoplasia and neoplasia, in clinical cases has not been described. The objective of this study was to illustrate application of the algorithm by estimating subject-specific adrenal gland volume in a historical cohort of dogs with known adrenal disease. Forty-six dogs that underwent CT and subsequent adrenalectomy were included. Clinical records and CT images from dogs that underwent adrenalectomy and histologic examination of the excised adrenal gland(s) were reviewed. Normal adrenal gland volumes for each dog were estimated using the algorithm, and compared with measured volumes of the affected glands. Linear measurement of the largest lesion diameter was also recorded. Fifty-eight adrenal glands were removed from 46 dogs, with pathology confirmed in all glands. Pathology included 28 adenomas, 13 carcinomas, 11 pheochromocytomas and 6 other benign pathologies. The volume of all removed adrenal glands was measured to be larger than the expected normal volume estimated by the algorithm, ranging from 1.1 to 212.9 times larger than estimated. Adrenal glands with malignant and benign pathology showed variable volumes with overlapping ranges recorded. Assessment of the dimensions of any focal lesion against a cut-off of 20 mm failed to discriminate malignancy. This study illustrates and supports the application of a validated volumetric algorithm for estimation of subject-specific adrenal gland volume to identify the presence of pathology and as a tool to assist clinical decision-making.

Long-Term outcome following surgical excision of large, low to intermediate grade soft tissue sarcomas in dogs.

INTRODUCTION: Soft tissue sarcomas (STS) represent a heterogeneous group of tumours, with varying mesenchymal cell origin, size and histological grade. Large soft tissue sarcomas pose a surgical challenge due to feasibility of excision, and are often dismissed as good surgical candidates due to an anticipated poor prognosis. OBJECTIVE: To evaluate the long-term outcome of dogs that underwent surgical excision of large (≥5 cm), low to intermediate grade, soft tissue sarcomas. METHODS: Medical records of dogs that presented for STS excision between 2009 and 2021 were reviewed. Information was obtained regarding signalment, tumour location and size, preoperative cytology and histology, preoperative imaging, surgical findings, postoperative histological diagnosis and outcome. Dogs were included in the study if they underwent surgical excision of a de novo cutaneous or subcutaneous STS, which measured at least five centimeters in one plane, and was histologically diagnosed as low-intermediate grade. Long-term follow-up data were obtained via consultation, telephone or email. RESULTS: Thirty-nine dogs with large, low-intermediate grade STS were included. Most tumours were Grade 1 (28/39), located predominantly on the thigh and thorax (17/39). Tumours were removed by at least a narrow margin excision (≥1 cm) and deep fascial plane in all cases. Histological margins were deemed complete in 15/39, close (1-3 mm) in 8/39, incomplete in 4/39, and unknown in 12/39. All sites were closed primarily, either directly (22/39) or with flap reconstruction (17/39). Long-term follow-up (median 1064 days) reported good postoperative function, with owner reported local recurrence in 2/39. Minor complications occurred in 10/39 and major complications requiring surgical intervention occurred in 5/39. CLINICAL SIGNIFICANCE: Large, low-intermediate grade STSs can be surgically excised with good long-term function and outcome, where consideration is given to appropriate case selection and planning. If skin flap reconstruction is required, owners should be made aware of the possible complications associated with their use.

Seed skin grafts for reconstruction of distal limb defects in 15 dogs.

OBJECTIVES: To report the surgical technique of seed skin grafting and clinical application for reconstruction of wounds on the distal limb of client-owned dogs. MATERIALS AND METHODS: Medical records from The Animal Hospital at Murdoch University were retrospectively reviewed for dogs requiring reconstruction using seed grafting for distal limb skin defects between January 2009 and May 2020. RESULTS: Fifteen dogs were included. Grafting was performed on distal limb wounds at or below the carpus or tarsus, following trauma (n = 12) or neoplasia excision (n = 3). Complete epithelialisation with minimal contracture was recorded at a median of 4 weeks (range 3 to 8 weeks) after implantation. Median follow-up was 37 months (range 3 to 55 months) after grafting. Postoperative complications included epidermal inclusion cyst in two dogs. Good functional outcome with acceptable cosmesis despite sparse hair growth was achieved in all cases. CLINICAL SIGNIFICANCE: Seed grafting is a simple technique that can be used reliably to reconstruct wounds on the distal limb in dogs where other reconstructive techniques are not suitable. Complete epithelialisation with sparse hair growth, good long-term functional outcome and minimal complications can be expected.

Short-term outcome of adrenalectomy in dogs with adrenal gland tumours that did not receive pre-operative medical management.

OBJECTIVE: Review medical records of dogs that underwent adrenalectomy without pre-operative medical management, to examine the peri-operative morbidity and mortality. DESIGN: Case series of 65 dogs. METHODS: Medical records were reviewed. Features recorded included the histologic diagnosis, intra-operative hypertension or tachycardia, requirement for cavotomy, administration of intra- and post-operative corticosteroids, performance of additional surgery and the occurrence of peri-operative complications. Dogs requiring emergency surgery were excluded. RESULTS: Of the 65 dogs, 49 had adrenocortical tumours (11 bilateral), 13 had pheochromocytomas (one bilateral) and three dogs had tumours in both adrenal glands of a different tumour type. Five dogs had caudal vena cava invasion and 33 had additional procedures performed at the same time. Mortality occurred in 1/65 dogs (1.5%; 95% CI 0.03%-8.2%), major complications were identified in 1/65 dogs (1.5%; 95% CI 0.03%-8.2%) and minor complications occurred in 10/53 dogs (15%; 95% CI 8.6%-26%). CONCLUSION: Based on the limited peri-operative complications and low mortality in this pre-operatively untreated cohort, and based on critique of the available literature, the added value afforded by pre-operative treatment is questioned. With appropriate management, adrenal tumours can be removed with few peri-operative complications and low mortality.

Computed tomographic findings, surgical management and postoperative outcomes of large intermuscular lipomas in the hindlimb of 11 dogs.

OBJECTIVE: Lipomas are benign adipose tissue tumours of mesenchymal origin and can originate in various locations. Intermuscular lipomas in the thigh can cause substantial hindlimb expansion in the dog. We describe the computed tomography findings, surgical management and the outcomes of 11 dogs with large intermuscular lipomas of the hindlimb. DESIGN: Retrospective case series. METHODS: Medical records between 2009 and 2019 of dogs presenting to The Animal Hospital at Murdoch University were reviewed. Inclusion criteria included dogs with a histologically confirmed, large hindlimb lipoma that was surgically excised following preoperative computed tomography (CT) imaging. RESULTS: CT with intravenous contrast revealed a well-defined, smoothly marginated, fat attenuating mass with minimal vascularity, separating the muscle bellies of the caudal hindlimb. The mass was often in close proximity to the femoral artery and vein. All lipomas were marginally excised. At surgery, some lipomas were intimately associated with the sciatic nerve and some showed infiltration of, or attachment to, neighbouring muscle that could be excised en bloc with the lipoma. Postoperative closed-suction wound drainage was used in 6 of 11 dogs. One dog required revision surgery due to partial wound dehiscence. Long-term follow-up with owners reported good postoperative function of the affected hindlimb in all dogs. One dog developed an infiltrative lipoma in the same location 22 months post-excision. CONCLUSION: Preoperative CT allowed a presumptive diagnosis of intermuscular lipoma and facilitated surgical planning for marginal excision. Large intermuscular lipomas of the hindlimb can be safely excised with minimal short-term complications, good long-term functional outcome and low likelihood of recurrence.

Large-Volume Crystalloid Fluid Is Associated with Increased Hyaluronan Shedding and Inflammation in a Canine Hemorrhagic Shock Model.

Shedding of the endothelial glycocalyx precedes leukocyte activation and adherence in acute inflammation. Rapid administration of crystalloid or colloid fluids for treating hemorrhagic shock may cause endothelial glycocalyx shedding, thereby increasing inflammation. This study aimed to compare the effect of different fluid treatments in a canine shock model on glycocalyx biomarker, hyaluronan, and inflammatory biomarkers. Greyhound dogs under general anesthesia subject to hemorrhage for 60 min were given 20 mL kg-1 of either fresh whole blood (FWB), hydroxyethyl starch (HES) 130/0.4, 4% succinylated gelatin (GELO), or 80 mL kg-1 of isotonic crystalloid (CRYST) over 20 min (n = 6 per group). Plasma biomarkers hyaluronan, interleukin (IL) 6, 8, 10, tumor necrosis factor-α, monocyte chemoattractant protein-1, keratinocyte chemokine-like, and atrial natriuretic peptide were measured at baseline, end of hemorrhage (Shock), end of fluid administration (T20), and then 40 (T60), 100 (T120), and 160 (T180) minutes later. Biomarker concentrations were compared between groups using the Kruskal-Wallis test or Fisher's exact test (measurable versus unmeasurable) (significance set at P < 0.05). Hyaluronan concentration peaked early in the CRYST group at T20, compared to HES (P = 0.005) and GELO (P = 0.018), and later in the GELO group at T60, compared to FWB (P < 0.001). The CRYST group had significantly more samples with measurable IL6 at T180 (P = 0.015), compared to GELO, and IL10 at T60, T120, and T180 (all P = 0.015), compared to FWB. There were no significant differences in other biomarker concentrations. In conclusion, rapid large-volume crystalloid administered for hemorrhagic shock was associated with increased hyaluronan and a greater inflammatory response.

Modified rib pivot lateral thoracotomy: a case series.

OBJECTIVE: To describe a modified rib pivot thoracotomy and its clinical application in client-owned dogs and cats. STUDY DESIGN: Case series of 24 dogs and 1 cat requiring a thoracotomy. METHODS: A lateral thoracic incision over the required thoracic segment was made. The latissimus dorsi muscle was reflected dorsally. The predetermined rib was identified and the periosteum overlying the rib was elevated circumferentially, avoiding the intercostal neurovascular structures. Holes were pre-placed above and below the proposed osteotomy site. The rib was osteotomised and pivoted cranially. The pleura was incised and the required intrathoracic procedure was then performed. The thoracic cavity was closed by pre-placement of a suture through the pre-placed holes within the osteotomised rib. The pleura and intercostal musculature were closed, avoiding the intercostal neurovascular structures. The rib was re-apposed and the lateral approach was closed. The cases included were reviewed for both the rib pivoted as per the procedure required and postoperative complications. RESULTS: The study group comprised 8 Staffordshire Bull Terriers, 2 Poodles, 2 German Shepherd Dogs, 1 each of Basset Hound, Rhodesian Ridgeback, Golden Retriever, Australian Shepherd, Vizsla, Bull Mastiff, Schnauzer, Jack Russell Terrier, Bulldog, Deerhound, Labrador Retriever and Australian Terrier, and 1 cat. A modified rib pivot thoracotomy was performed for lung lobectomy (n = 11), oesophagectomy (7), subtotal pericardectomy (5), patent ductus arteriosus ligation (1) and thoracic duct ligation (1). Follow-up ranged from 2 to 40 weeks postoperatively. Postoperative complications included seroma formation in two dogs. CONCLUSION: A modified rib pivot thoracotomy should be considered as an alternative lateral thoracic approach with good exposure, minimal complications and low morbidity.

Interleukin-8, interleukin-1ß and tumour necrosis factor-α in sequential units of packed red blood cells collected from retired racing Greyhounds.

BACKGROUND: We hypothesised that concentrations of interleukin-8 (IL-8), interleukin-1ß (IL-1ß) and tumour necrosis factor-α (TNF-α) would increase during storage in the third sequential unit (U3) of canine packed red blood cells (PRBC) collected from terminal donors in haemorrhagic shock. We further hypothesised that leucoreduction would prevent cytokine accumulation in U3 and that cytokine concentrations in U3 would be higher than in the first units (U1) collected from the same dogs. METHODS: U1 and U3 were each collected from 12 anaesthetised healthy Greyhounds. Removal of leucocytes from half of each PRBC unit produced one leucoreduced (LR) and one non-leucoreduced (NLR) unit. Canine IL-8, IL-1ß and TNF-α concentrations were measured in samples collected from the units during storage on days 0, 10, 20, 30 and 37. RESULTS: The IL-8 concentration in U3 NLR units was significantly higher on days 10, 20, 30 and 37 than on day 0 and was significantly higher than in the LR units at all time points. The IL-1ß concentration in U3 did not change over time, or between LR and NLR units. TNF-α was not detected in any unit. There were no significant differences in IL-8 or IL-1ß concentrations between U3 and U1 at any time point; however, some NLR U3 units had markedly elevated IL-8 concentrations at day 37 (2060-20,682 pg/mL) compared with NLR U1 units (3369-5280 pg/mL). CONCLUSION: NLR U3 units collected from dogs in haemorrhagic shock showed a significant increase in IL-8 concentrations during storage. Leucoreduction was effective at preventing the accumulation of IL-8. There was no difference detected between U3 and U1.

Survival of two dogs with pyothorax secondary to perforating oesophageal foreign body.

CASE REPORT: Two dogs with an oesophageal foreign body (FB) were diagnosed with secondary pyothorax at the time of presentation. One dog was managed with surgical FB removal, pleural lavage and thoracostomy tube placement. Following surgery, it was admitted to the intensive care unit for oxygen therapy, antimicrobial and analgesic administration, fluid therapy, thoracic drainage and enteral nutrition. The other dog was managed with endoscopic FB removal, thoracostomy tube placement with continuous suction, and similar aftercare in the intensive care unit. Both survived to discharge from hospital. CONCLUSION: This report details the treatment and survival of two dogs with secondary pyothorax associated with oesophageal FB, with successful management through supportive care, oesophageal rest and treatment of infection.

Computed tomography findings and surgical outcomes of dermoid sinuses: a case series.

OBJECTIVE: This case series describes the computed tomography (CT) and surgical findings of nine dogs with dermoid sinuses. METHODS: Medical records were reviewed and summarised. RESULTS: CT with intravenous contrast showed a superficial, peripherally contrast-enhancing, fluid-filled structure with a contrast-enhancing, soft tissue-attenuating tract that extended from the skin through the dorsal midline soft tissues, often to the level of the nuchal ligament. The tract often extended in an oblique direction to the nuchal ligament, but the tract ventral to the nuchal ligament, found at surgery, was not always discernible on CT. The dermoid sinuses were excised from all dogs. At surgery, the tract often extended ventral to the nuchal ligament, terminating on the vertebra. The most ventral aspect of the tracts involved a fibrous strand extension of the sinus, which was not discernible on CT. CONCLUSION: Preoperative CT facilitated the diagnosis of a dermoid sinus and directed surgical planning; however, careful dissection beyond the nuchal ligament is imperative for complete excision.

Ozonated water is inferior to propanol-based hand rubs for disinfecting hands.

Ozone is a strong oxidizing biocide that has broad-spectrum antimicrobial properties. The aim of the study was to compare the efficacy of ozone to a propanol-based hand rub for hand disinfection. Twenty subjects were enrolled in an in-vivo cross-over trial (prEN 12791). Subjects treated their hands with the reference procedure (propan-1-ol 60%) or with ozone (4 ppm). Post-wash bacterial counts were determined from one hand (immediate effect), and from the other hand that had been gloved for 3h (delayed effect). The investigation indicated that ozone is inferior to propan-1-ol 60% hand rub for hand asepsis.

Preoperative factors associated with hypotension in young anaesthetised dogs undergoing elective desexing.

OBJECTIVES: Document the proportion of dogs with perioperative hypotension and explore the association of sex, age and body mass and indices of hydration with mean arterial blood pressure (MAP) in two cohorts of young, healthy anaesthetised dogs. METHODS: Dogs were anaesthetised with a standardised protocol. The proportion of dogs with invasively measured MAP <60 mmHg for ≥10 min was recorded. The area under the MAP*time curve (MAP-AUC) was calculated for a standard perioperative period. The association of explanatory variables, including sex, age, body mass and indices of hydration (urine specific gravity (USG), packed cell volume and total solids) measured prior to surgery, with the MAP-AUC was explored using regression analysis in the first cohort (n = 71) and externally validated in the second cohort (n = 24). RESULTS: In cohort 1, 35 of 71 dogs (0.49, 95% confidence interval (CI) 0.37-0.61) dogs and 17/24 dogs in cohort 2 (0.71, 95% CI 0.53-0.89) developed hypotension. Regression analysis showed that age and USG were significantly associated with MAP-AUC for cohort 1 (P = 0.0138). There was a positive association of MAP-AUC with age and a negative association with USG. The association of MAP-AUC with USG was supported in cohort 2, with a significant negative association (P = 0.014, r = -0.54) CONCLUSION: The high frequency of hypotension in both cohorts supports blood pressure monitoring during anaesthesia of young, healthy dogs. USG, an index of hydration, appears negatively associated with MAP during anaesthesia, suggesting that subclinical dehydration may contribute to lower MAP during surgical anaesthesia.

Prevalence of bacteriuria in dogs without clinical signs of urinary tract infection presenting for elective surgical procedures.

OBJECTIVES: To determine the frequency of bacteriuria in dogs presenting for elective surgery, to compare the frequency of bacteriuria in dogs presenting for orthopaedic (non-neurological) procedures to that of dogs presenting for soft tissue procedures and to measure the agreement of microscopic visualisation of bacteria in urine sediment with the occurrence of bacterial growth on culture. METHODS: Prospective cohort study of 140 client-owned dogs. Urine was collected via prepubic cystocentesis prior to or immediately after induction of anaesthesia. Urine was submitted for quantitative bacteriological culture and urinalysis. The dogs' age, sex, weight and breed were recorded, as well as the surgical procedure performed. RESULTS: In total, 80 orthopaedic and 60 soft tissue surgical cases were included in the study; 3 dogs (2.1%) returned bacterial growth on culture (positive urine culture) and 19 (13.6%) recorded urine sediment with pyuria and/or bacteriuria on urinalysis (positive urinalysis). All dogs with positive urine culture were female and two of them underwent orthopaedic procedures. Each bitch had growth of Escherichia coli >10(5) CFU/mL. The agreement between positive urinalysis and positive urine culture was poor (κ = 0.15). CONCLUSIONS: The prevalence of bacteriuria in dogs without clinical signs of urinary tract infection in this population was low (2.1%). An at-risk population could not be identified because of the small number of positive outcomes. A positive urinalysis showed poor agreement with urine culture results and therefore the decision to treat without performing a urine culture is not advised.

Persistent breeding-induced endometritis after hysteroscopic insemination in the mare.

Low-dose insemination has been proposed to reduce persistent breeding-induced endometritis (PBIE) in mares with delayed uterine clearance (DUC). Others proposed that hysteroscopic insemination induces an exaggerated inflammatory response and should be avoided in DUC mares. The objectives here were to evaluate presence and severity of PBIE in normal and DUC mares after hysteroscopic insemination with fresh semen, and to determine if hysteroscopy could be used in DUC mares without inducing excessive inflammation. Reproductively normal (n = 4) and DUC (n = 5) mares received four treatments in random order: uterine body insemination (UB, 1 × 10(9) spermatozoa, 20 ml), hysteroscopic insemination (HYST, 5 × 10(6) spermatozoa, 0.5 ml), sham hysteroscopic insemination (SHAM, semen extender, 0.5 ml) and hysteroscopic infusion of seminal plasma (SP, 0.5 ml). Significantly more DUC (50%) mares than normal (14%) mares accumulated intrauterine fluid 24 h post-treatment. The difference in fluid accumulation between DUC (40%) mares and normal (7%) mares was also significant 48 h post-treatment. Fluid scores were not significantly different between treatments in normal mares. However, treatments HYST and SHAM resulted in significantly higher fluid scores 24 h but not 48 h post-treatment in DUC mares. There was no effect of treatment or mare group on the percentage and total number of neutrophils in uterine fluid 48 h post-treatment. Percentage of neutrophils was correlated with duration of hysteroscopy in normal mares, with procedures lasting ≥ 9 min associated with PBIE. There was no effect of mare group, treatment or duration of hysteroscopy on pregnancy rate. Hysteroscopy induces a transient inflammation that is not more severe than that after conventional artificial insemination, suggesting no contraindication to its use in DUC mares.

Changes in tibial plateau angles after tibial plateau-levelling osteotomy in dogs with cranial cruciate deficiency.

AIM: To investigate changes in tibial plateau angles measured immediately after surgery and at follow-up in dogs treated for cranial cruciate ligament deficiency using tibial plateau-levelling osteotomy, and to determine the association of host and external factors with this change. METHODS: Records were analysed from dogs treated using tibial plateau-levelling osteotomy. Data included the dog's age, gender, breed, and bodyweight; the tibial plateau angle and mechanical medial proximal tibial angle measured in medio-lateral and caudo-cranial radiographs, respectively, pre- and post-operatively and at follow-up; interval to follow-up, use of a tibial tuberosity pin, type of plate, diameter of the osteotomy blade, and use of the alignment jig during surgery. RESULTS: Data from 364 stifles were analysed, including 163 from male dogs; 52 had bilateral tibial plateau-levelling osteotomy. Mean weight was 35.9 (SD 9.8) kg and age was 5.4 (SD 2.6) years. Mean interval to follow-up was 47 (SD 5.7) days. Overall, the mean tibial plateau angle was reduced from 26.2° (SD 4.7) pre-operatively to 4.5° (SD 3.5) post-operatively, and increased to 7.2° (SD 4.1) at follow-up (p<0.001). The mean mechanical medial proximal tibial angle was reduced from 4.1° (SD 2.4) pre-operatively to 2.7° (SD 2.2) post-operatively, and increased to 3.1° (SD 2.5) at follow-up (p<0.001). The type of plate used was associated with the change in angles between post-operative and follow-up measurements (p = 0.03), but there was no association with any other variables examined. Post-operatively, the tibial plateau angle was 4-6° for 112/364 (30.8%) stifles, and was 4-14° for 125/364 (34.3%) stifles. Type of plate used was associated with the odds of achieving these recommended angles. CONCLUSION: The angular changes in the proximal tibia after tibial plateau-levelling osteotomy were affected by the type of plate used for osteosynthesis, but no significant host factors were identified. Changes in the mechanical medial proximal tibial angle following surgery were also observed despite the use of an alignment jig during surgery. CLINICAL RELEVANCE: Loss in angular reduction following plateau-levelling osteotomy should be expected when using the plate designs included in this study. Placement of a pin through the tibial tuberosity did not prevent the increase in tibial plateau angle between immediate post-operative and follow-up measurements. The use of the alignment jig did not affect the induction of a varus change in the mechanical medial proximal tibial angle during surgery nor the change between immediate post-operative and follow-up measurement.

Evaluation of intra-articular and subcutaneous administration of meloxicam for postoperative analgesia following stifle surgery in dogs.

The objective of this study was to compare the efficacy of meloxicam when given by intra-articular (IA) and subcutaneous (SC) routes of administration for postoperative analgesia versus a placebo for dogs undergoing stifle surgery. Twenty-five dogs with cranial cruciate ligament rupture (CCLR) were randomly assigned to one of three treatment groups, each with nine dogs, before surgical repair of twenty-seven stifles using a modified lateral retinacular imbrication technique. Group 1 dogs received IA administration of meloxicam and SC placebo. Group 2 dogs received IA placebo and SC meloxicam. Group 3 dogs received IA and SC administration of placebo. Dogs were assessed for pain by blinded observers using a visual analog scale (VAS), a numerical pain scoring system (NPS), and measurement of pain threshold using an algometer applied to the affected stifle. Assessments were made prior to pre-medication, postoperatively at the time of extubation, and at 1, 2, 4, 6, 8, 10, 12, 16, 20, and 24 hours following extubation. The results did not identify any significant effect of treatment between groups on the VAS data, algometer readings, or NPS data. Significantly increased VAS scores and decreased algometer readings were noted from preoperative to postoperative times. No differences were noted in early postoperative pain between dogs treated with IA meloxicam, SC meloxicam, or placebo. While intra-articular non-steroidal anti- inflammatory drug administration has shown efficacy in joint surgery for people, we did not find any evidence to support its use in dogs undergoing repair of CCLR.

Cardiopulmonary, blood and peritoneal fluid alterations associated with abdominal insufflation of carbon dioxide in standing horses.

REASONS FOR PERFORMING STUDY: Abdominal insufflation is performed routinely during laparoscopy in horses to improve visualisation and facilitate instrument and visceral manipulations during surgery. It has been shown that high-pressure pneumoperitoneum with carbon dioxide (CO2) has deleterious cardiopulmonary effects in dorsally recumbent, mechanically ventilated, halothane-anaesthetised horses. There is no information on the effects of CO2 pneumoperitoneum on cardiopulmonary function and haematology, plasma chemistry and peritoneal fluid (PF) variables in standing sedated horses during laparoscopic surgery. OBJECTIVES: To determine the effects of high pressure CO2 pneumoperitoneum in standing sedated horses on cardiopulmonary function, blood gas, haematology, plasma chemistry and PF variables. METHODS: Six healthy, mature horses were sedated with an i.v. bolus of detomidine (0.02 mg/kg bwt) and butorphanol (0.02 mg/kg bwt) and instrumented to determine the changes in cardiopulmonary function, haematology, serum chemistry and PF values during and after pneumoperitoneum with CO2 to 15 mmHg pressure for standing laparoscopy. Each horse was assigned at random to either a standing left flank exploratory laparoscopy (LFL) with CO2 pneumoperitoneum or sham procedure (SLFL) without insufflation, and instrumented for measurement of cardiopulmonary variables. Each horse underwent a second procedure in crossover fashion one month later so that all 6 horses had both an LFL and SLFL performed. Cardiopulmonary variables and blood gas analyses were obtained 5 mins after sedation and every 15 mins during 60 mins baseline (BL), insufflation (15 mmHg) and desufflation. Haematology, serum chemistry analysis and PF analysis were performed at BL, insufflation and desufflation, and 24 h after the conclusion of each procedure. RESULTS: Significant decreases in heart rate, cardiac output and cardiac index and significant increases in mean right atrial pressure, systemic vascular resistance and pulmonary vascular resistance were recorded immediately after and during sedation in both groups of horses. Pneumoperitoneum with CO2 at 15 mmHg had no significant effect on cardiopulmonary function during surgery. There were no significant differences in blood gas, haematology or plasma chemistry values within or between groups at any time interval during the study. There was a significant increase in the PF total nucleated cell count 24 h following LFL compared to baseline values for LFL or SLFL at 24 h. There were no differences in PF protein concentrations within or between groups at any time interval. CONCLUSIONS: Pneumoperitoneum with CO2 during standing laparoscopy in healthy horses does not cause adverse alterations in cardiopulmonary, haematology or plasma chemistry variables, but does induce a mild inflammatory response within the peritoneal cavity. POTENTIAL RELEVANCE: High pressure (15 mmHg) pneumoperitoneum in standing sedated mature horses for laparoscopic surgery can be performed safely without any short-term or cumulative adverse effects on haemodynamic or cardiopulmonary function.

Transdermal methimazole treatment in cats with hyperthyroidism.

The objectives of this study were to assess serum thyroxine concentrations and clinical response in hyperthyroid cats to treatment with transdermal methimazole, and to determine if further investigation is indicated. Clinical and laboratory data from 13 cats with hyperthyroidism were retrospectively evaluated. Methimazole (Tapazole, Eli Lilly) was formulated in a pleuronic lecithin organogel (PLO)-based vehicle and was applied to the inner pinna of the ear at a dosage ranging from 2.5mg/cat q 24h to 10.0mg/cat q 12h. During the treatment period, cats were re-evaluated at a mean of 4.3 weeks (recheck-1), and again at a mean of 5.4 months (recheck-2). Clinical improvement was observed, and significant decreases in thyroxine concentrations were measured at recheck-1 (mean: 39.57nmol/L, SEM: 14.4, SD: 41.2) and recheck-2 (mean: 36.71nmol/L, SEM: 13.9, SD: 45.56) compared to pretreatment concentrations (mean: 97.5nmol/L, SEM: 11.42, SD: 39.5). No adverse effects were reported.

Alterations in systemic and local colonic hemodynamic variables associated with intravenous infusion of ATP-MgCl2 in healthy anesthetized horses.

OBJECTIVE: To characterize alterations in systemic and local colonic hemodynamic variables associated with IV infusion of ATP-MgCl2 in healthy anesthetized horses. ANIMALS: 12 adult horses. PROCEDURE: Six horses were given ATP-MgCl2, IV, beginning at a rate of 0.1 mg of ATP/kg of body weight/min with incremental increases until a rate of 1.0 mg/kg/min was achieved. The remaining 6 horses were given an equivalent volume of saline (0.9% NaCl) solution over the same time period. Colonic and systemic hemodynamic variables and colonic plasma nitric oxide (NO) concentrations were determined before, during, and after infusion. RESULTS: Infusion of ATP-MgCl2 caused a rate-dependent decrease in systemic and colonic vascular resistance, principally via its vasodilatory effects. A rate of 0.3 mg of ATP/kg/min caused a significant decrease in systemic and colonic arterial pressure and colonic vascular resistance without a significant corresponding decrease in colonic arterial blood flow. Consistent alterations in NO concentrations of plasma obtained from colonic vasculature were not detected, despite profound vasodilatation of the colonic arterial vasculature. CONCLUSIONS AND CLINICAL RELEVANCE: Results revealed that IV infusion of ATP-MgCl2 may be beneficial in maintaining colonic perfusion in horses with ischemia of the gastrointestinal tract, provided a sufficient pressure gradient exists to maintain blood flow.

Quantitation of adenine nucleotides in equine colonic mucosal tissue using high performance liquid chromatography.

The objectives were to use high performance liquid chromatography (HPLC) to validate an established method for adenine nucleotide separation in equine colonic mucosal tissue, to determine the inherent variability in the tissue and extraction method, and to determine the stability of ATP, ADP, and AMP in the tissue with time. Equine colonic mucosal tissue obtained from a single horse was immediately submersed in liquid nitrogen, and stored at -70 degrees C. Samples were lyophilized, extracted, and separated by HPLC. The limit of quantitation was 0.05 microg/mL. The coefficient of variation for the instrument was less than 10% for all nucleotides measured. When the tissue was not homogenized prior to sampling, there were significant differences in adenine nucleotide content between samples. However, when the tissue was homogenized prior to analysis, these differences were no longer significant. There was no significant decrease in ATP, ADP, or AMP content over a 54-day analysis period.