Comparison of the effect of oxygen supplementation using flow-by or a face mask on the partial pressure of arterial oxygen in sedated dogs.

AIMS To compare the effect of oxygen supplementation using flow-by or a face mask on the partial pressure of arterial oxygen (PaO2) in sedated dogs. METHODS Twenty healthy dogs weighing >15 kg, of mixed sex and breed, were enrolled in a randomised cross-over study. Each dog was sedated with I/M 0.015 mg/kg medetomidine and 0.5 mg/kg methadone. Twenty minutes later dogs were exposed to two 5-minute treatment periods of oxygen supplementation separated by a 15-minute washout period during which dogs were allowed to breathe room air. During the treatment periods, oxygen was delivered at a flow rate of 3 L/minute either through a face mask (face mask oxygenation), or via a tube held 2 cm from the dog's nares (flow-by oxygenation). The order in which the treatments were administered was randomised. Arterial blood was collected for blood gas analysis and rectal temperature measured at four times: prior to commencing treatments, after each treatment, and at the end of the 15 minutes washout period between treatments. RESULTS The mean PaO2 in arterial samples taken from the dogs after face mask oxygen supplementation was 371.3 (SE 13.74) mmHg which was higher than in samples taken after they received flow-by oxygen supplementation (182.2 (SE 6.741) mmHg; p<0.001). The mean PaO2 in samples taken after receiving either form of oxygen supplementation was higher than in samples taken after the dogs had been breathing room air (82.43 (SE 2.143) mmHg; p<0.001). There was no association between sex, age, weight or breed of dogs and blood gas parameters or rectal temperature (p>0.05). CONCLUSIONS Oxygen supplementation delivered using a face mask was more effective at increasing PaO2 than flow-by oxygen supplementation. Flow-by oxygen supplementation at a distance of 2 cm from the nose may be a suitable alternative when the use of a face mask is not tolerated by the patient.

Effects of topical treatment of cannabidiol extract in a unique manuka factor 5 manuka honey carrier on second intention wound healing on equine distal limb wounds: a preliminary study.

OBJECTIVE: Evaluate the effect of topical 1% cannabidiol on second intention wound healing in distal limb wounds of horses. DESIGN: Experimental. ANIMALS: Six Standardbred horses. METHODS: A total of five 2.5 cm × 2.5 cm full thickness skin wounds were created on the dorsomedial aspect of the metacarpi of 6 horses. Wounds were contaminated with faeces on the day of wound creation. Each wound was then assigned to a treatment group; compounded 1% cannabidiol in unique manuka factor (UMF) 5 manuka honey, UMF 5 manuka honey, UMF 20 manuka honey or saline. Each treatment was applied topically daily for a total of 42 days. Legs were bandaged and bandages were changed, daily, for 13 days postoperatively. Digital photographs of each wound were taken on day 1 then weekly for 6 weeks. Wound size, daily healing rate and total time to healing were recorded and compared statistically. RESULTS: Irrespective of the treatment, wounds did not retract as expected in the first 7 days after wound creation. There was no difference in wound area, daily healing rate, days to complete healing between treatment groups. CONCLUSIONS: This preliminary study failed to demonstrate any difference in wound healing variables between treatment groups in this model of second intention wound healing. This was unexpected due to the established effects of UMF 20 manuka honey on wound healing using the same model. This may be due to systemic effects of cannabidiol and study design. Further research into the use of cannabidiol in equine wounds is warranted.

Effect of bandaging on second intention healing of wounds of the distal limb in horses.

OBJECTIVE: To evaluate the effect of a non-occlusive dressing incorporated in a 3-layer bandage on second intention healing of wounds of the distal portion of the limb. STUDY DESIGN: Untreated wounds in 33 adult horses used in four studies using the same wound-healing model conducted over 5 years. METHODS: Standardised, full-thickness wounds were made in the skin overlying the dorsomedial aspect of the mid-metacarpus; 17 horses were bandaged with a non-occlusive dressing covered by gauze-coated cotton wool that was compressed with adhesive tape; 16 horses were left unbandaged. Wounds were photographed weekly for 9 weeks and the images were analysed electronically. RESULTS: There were significant effects associated with bandage (P < 0.0001), week (P < 0.001), and bandage by week interaction (P < 0.0001). There was no difference in wound area at the first time-point after wound creation (P = 0.38). After week 1, there was a difference between bandaged and unbandaged wounds in wound area at each measurement until the end of the study. Bandaged wounds showed greater and more prolonged retraction. Unbandaged wounds retracted for 2 weeks before beginning to contract, whereas bandaged wounds continued to retract for 3 weeks. In bandaged wounds excess granulation tissue required regular trimming, but not in unbandaged wounds. There was no difference between groups in the total days to healing or the overall rate of healing. CONCLUSIONS: These results should be treated with caution until validated with contemporaneous, controlled studies. Covering a wound with a non-occlusive dressing in a 3-layer bandage led to greater wound retraction, modulated the rate of wound contraction and promoted excessive granulation tissue. If excessive granulation tissue is excised regularly, bandaging has no effect on total time to healing.

Speed of induction of anaesthesia in dogs administered halothane, isoflurane, sevoflurane or propofol in a clinical setting.

OBJECTIVE: To compare the speed and quality of induction of general anaesthesia using three different inhalant agents and one intravenous agent, in healthy dogs undergoing desexing surgery. MATERIALS AND METHODS: Less excitable dogs were not premedicated; others were premedicated with intramuscular acepromazine and morphine. Anaesthesia induction protocol was randomly assigned, with halothane, isoflurane or sevoflurane delivered by mask, or propofol delivered intravenously. Maximum vaporiser settings were used for inhalant inductions. Induction of anaesthesia was considered complete at the time of endotracheal intubation. Quality of induction was scored by the administering veterinarian. RESULTS: Seventy-one dogs were enrolled. Twenty-four received no premedication and 47 received premedication. Isoflurane inductions were significantly faster than halothane inductions (2.86 +/- 0.25 vs 3.71 +/- 0.22 min; mean +/- SE, P = 0.013). Sevoflurane inductions (3.29 +/- 0.24 min) were not significantly different from either halothane (3.71 +/- 0.22 min, P = 0.202) or isoflurane inductions (2.86 +/- 0.25 min, P = 0.217). Induction with propofol (1.43 +/- 0.13 min) was significantly faster than inhalant induction (P < 0.001 in each case). Premedication decreased the dose requirement and time to induction for dogs induced with propofol, but did not significantly change the time to intubation for inhalant inductions. Dogs administered propofol and/or premedication were significantly more likely to have an excellent quality of induction, but there was no difference between inhalant agents in terms of induction quality. CONCLUSION: Sevoflurane possesses chemical properties that should produce a more rapid induction of anaesthesia in comparison to halothane or isoflurane. However, in clinical practice patient related factors outweigh this improvement.

Effect of reducing inspired oxygen concentration on oxygenation parameters during general anaesthesia in horses in lateral or dorsal recumbency.

OBJECTIVE: To compare the effects of two concentrations of oxygen delivered to the anaesthetic breathing circuit on oxygenation in mechanically ventilated horses anaesthetised with isoflurane and positioned in dorsal or lateral recumbency. METHODS: Selected respiratory parameters and blood lactate were measured and oxygenation indices calculated, before and during general anaesthesia, in 24 laterally or dorsally recumbent horses. Horses were randomly assigned to receive 100% or 60% oxygen during anaesthesia. All horses were anaesthetised using the same protocol and intermittent positive pressure ventilation (IPPV) was commenced immediately following anaesthetic induction and endotracheal intubation. Arterial blood gas analysis was performed and oxygenation indices calculated before premedication, immediately after induction, at 10 and 45 min after the commencement of mechanical ventilation, and in recovery. RESULTS: During anaesthesia, the arterial partial pressure of oxygen was adequate in all horses, regardless of position of recumbency or the concentration of oxygen provided. At 10 and 45 min after commencing IPPV, the arterial partial pressure of oxygen was lower in horses in dorsal recumbency compared with those in lateral recumbency, irrespective of the concentration of oxygen supplied. Based on oxygenation indices, pulmonary function during general anaesthesia in horses placed in dorsal recumbency was more compromised than in horses in lateral recumbency, irrespective of the concentration of oxygen provided. CONCLUSION: During general anaesthesia, using oxygen at a concentration of 60% instead of 100% maintains adequate arterial oxygenation in horses in dorsal or lateral recumbency. However, it will not reduce pulmonary function abnormalities induced by anaesthesia and recumbency.

Effect of hypothermia on recovery from general anaesthesia in the dog.

OBJECTIVE: To discern the effects of anaesthesia protocols and decreasing core body temperature on time to recovery from general anaesthesia. MATERIALS AND METHODS: Healthy adult dogs undergoing desexing surgery were enrolled. More excitable dogs were premedicated with intramuscular acepromazine and morphine; calmer dogs were not premedicated. Anaesthesia was induced using halothane, isoflurane or sevoflurane delivered by mask, or by intravenous propofol, and maintained in standard fashion using one of the three inhalant agents. Thermostat controlled heat mats were used during surgical preparation and surgery. Oesophageal temperature was recorded throughout surgery. The time from cessation of anaesthetic administration until the dog successfully raised itself to sternal recumbency was considered the time of recovery. RESULTS: Sixty-nine dogs completed the study, 42 males anaesthetised for 60.4 +/- 20.5 min, and 27 females anaesthetised for 85.4 +/- 33.2 min. Oesophageal temperature at the end of surgery was 36.8 +/- 0.80 degrees C. Oesophageal temperature had a significant effect on recovery time, with lower temperatures contributing to slower recoveries. Premedication significantly lengthened recovery times. The choice of induction or maintenance anaesthetic agent had no effect on recovery time. DISCUSSION: Hypothermia is a common complication of general anaesthesia and surgery. Amongst other deleterious effects, it is associated with slower recovery from anaesthesia, likely due to a number of different mechanisms.

End-to-side anastomosis of the left ventral colon to the small colon in a neonatal foal with segmental agenesis of the large colon.

CASE REPORT: A newborn foal was referred for evaluation because it had not passed meconium, despite the administration of four enemas. Abdominal radiographs and ultrasound scans showed generalised gaseous distension of the intestine and there was no observable meconium in the colon. Positive contrast colography showed contrast medium extending to the transverse colon. An exploratory laparotomy confirmed the absence of the left and right dorsal colon and the pelvic and diaphragmatic flexures. An end-to-side anastomosis of the left ventral colon to the midpoint of the small colon was performed. The foal recovered from anaesthesia and surgery uneventfully and immediately began suckling from the mare, with no signs of abdominal pain in the postoperative period. The foal began to pass soft faeces 3 days after surgery and at 6 months after surgery the foal was clinically normal and growing at a similar rate to its cohort. CONCLUSION: Intestinal atresia is a rare condition in foals, but should be considered as a differential diagnosis in foals that fail to pass meconium. Early recognition and surgical intervention can offer an improved chance of short-term survival in cases where there is adequate intestine to anastomose. An end-to-side anastomosis technique can be used where an end-to-end technique is not practical because of the difference in diameter of the proximal and distal intestinal segments.

Comparison of the effects of topical application of UMF20 and UMF5 manuka honey with a generic multifloral honey on wound healing variables in an uncontaminated surgical equine distal limb wound model.

OBJECTIVE: To compare the effect of application of manuka honey with unique manuka factor (UMF) 5 or 20 with a generic multifloral honey on equine wound healing variables. METHODS: Two full-thickness skin wounds (2.5 × 2.5 cm) were created on the metatarsus of both hindlimbs of eight Standardbred horses. The wounds on each horse were assigned to 1 of 4 treatments: UMF20 (UMF20) and UMF5 (UMF5) manuka honey; generic multifloral honey (GH); and a saline control. Bandages were changed daily for 12 days, after which treatment was stopped and the bandages were removed. Wound area was measured on day 1, then weekly until day 42. Overall wound healing rate (cm2 /day) and time to complete healing were recorded. RESULTS: There was no difference in wound area for any of the treatments on any measurement day except for day 21, where the mean wound area for wounds treated with UMF20 was smaller than the mean wound area for the UMF5-treated wounds (P = 0.031). There was no difference in mean (± SE) overall healing rate (cm2 /day) among the treatment groups. There were differences in mean (± SE) days to complete healing. Wounds treated with UMF20 healed faster than wounds treated with GH (P = 0.02) and control wounds (P = 0.01). CONCLUSIONS: Treatment of wounds with UMF20 reduced overall wound healing time compared with wounds treated with GH and control wounds. However, using this model the difference in the overall time to complete healing was small.

Pleuropneumonia as a sequela of myelography and general anaesthesia in a Thoroughbred colt.

A 3-year-old Thoroughbred colt was presented to the University Veterinary Centre Camden for evaluation of ataxia. The horse was anaesthetised to facilitate cervical radiography and myelographic examination of the spinal cord. Recovery from anaesthesia was uneventful. Five days after general anaesthesia the horse re-presented with pleuropneumonia. It was euthanased 24 hours after presentation on humane grounds. Necropsy revealed severe tracheal erosion over the middle third of the ventral surface of the trachea, pleuropneumonia and narrowing of the cervical cord between C4 and C6. It is postulated that extension and flexion of the neck during myelography resulted in movement of the endotracheal tube cuff, causing the tracheal lesion and predisposing the colt to pleuropneumonia. Severe tracheal lesions and pleuropneumonia have not been reported as sequela of equine myelography, and should be considered as possible complications following repeated cervical manipulation during myelography in the horse.

Effect of Manuka honey gel on the transforming growth factor ß1 and ß3 concentrations, bacterial counts and histomorphology of contaminated full-thickness skin wounds in equine distal limbs.

OBJECTIVE: To investigate the effect of 66% Manuka honey gel on the concentrations of transforming growth factor (TGF)-ß1 and TGF-ß3, bacterial counts and histomorphology during healing of contaminated equine distal limb wounds. METHODS: In this experimental study of 10 Standardbred horses, five full-thickness skin wounds (2 × 1.5 cm) were created on one metacarpus and six similar wounds were created on the contralateral metacarpus. Wounds were assigned to three groups: non-contaminated control wounds; contaminated control wounds; contaminated wounds treated daily with 1 mL Manuka honey gel topically for 10 days. For the contaminated wounds, faeces were applied for 24 h after wound creation. In five horses wounds were bandaged and in the other five horses wounds were left without a bandage. Biopsies were taken on days 1, 2, 7 and 10 after wounding to evaluate the effects of Manuka honey gel, wound contamination and bandaging on TGF-ß1 and TGF-ß3 concentrations, aerobic and anaerobic bacterial counts, and histomorphology. RESULTS: Manuka honey gel had no significant effect on TGF-ß1 and TGF-ß3 concentrations or wound bacterial counts. Manuka honey gel decreased wound inflammation (days 7, 10), increased angiogenesis (days 2, 7, 10), increased fibrosis and collagen organisation (day 7) and increased epithelial hyperplasia (days 7, 10). CONCLUSIONS: Treatment with Manuka honey gel resulted in a more organised granulation tissue bed early in wound repair, which may contribute to enhanced healing of equine distal limb wounds.

Effect of activated protein C in second intention healing of equine distal limb wounds: a preliminary study.

OBJECTIVE: To investigate the effect of activated protein C (APC) on second intention healing of distal limb wounds in horses. METHODS: In this experimental study of eight Standardbred geldings, six full-thickness skin wounds (2 × 1.5 cm) were created on one metacarpus (biopsy limb) and five similar wounds were created on the contralateral metacarpus (photographed limb). Three wounds on the biopsy limb were treated topically with 190 µg APC on days 1, 3, 6 and 9, while the remaining three wounds were untreated (control). One treated and one control wound were biopsied on days 4, 7 and 11 for histopathology. Wounds on the photographed limb were treated with either 66% Manuka honey gel, a commercial antibiotic ointment (bacitracin-neomycin-polymixin B ointment; BNP) or petrolatum daily throughout healing, treated on days 1,3,6 and 9 with 190 µg APC or left untreated. These wounds were digitally photographed and the wound area measured on day 1, then weekly until day 49. Overall time to healing was recorded. RESULTS: There was no effect of APC on wound size, the rate of healing or the overall time to heal. However, compared with control wounds, histological scoring demonstrated enhanced epithelialisation (day 4) and angiogenesis (day 11). Wound healing variables for wounds treated with APC, Manuka honey gel and control wounds were not different and the variables for wounds treated with BNP and petrolatum demonstrated delayed healing. CONCLUSION: The improvements in histological scores in APC-treated wounds suggest further study into the effect of APC on second intention wound healing in horses is warranted.

Ventral midline caesarean section for dystocia secondary to failure to dilate the cervix in three alpacas.

Three alpacas that presented with dystocia characterised by failure of the cervix to dilate, underwent caesarean section. Surgery on each animal was performed through a ventral midline incision under general anaesthesia. Two live crias were delivered and one cria was dead at delivery. All three alpacas had retained foetal membranes for a period of 12 h to 4 d and one developed uterine prolapse, which was replaced using sedation and epidural anaesthesia. There were no complications associated with the surgical procedure and all three alpacas went on to have confirmed pregnancies. Caesarean section through a ventral midline incision should be considered an alternative for treatment of difficult dystocias in alpacas.

Equine castration: review of anatomy, approaches, techniques and complications in normal, cryptorchid and monorchid horses.

Complications associated with equine castration are the most common cause of malpractice claims against equine practitioners in North America. An understanding of the embryological development and surgical anatomy is essential to differentiate abnormal from normal structures and to minimise complications. Castration of the normal horse can be performed using sedation and regional anaesthesia while the horse is standing, or under general anaesthesia when it is recumbent. Castration of cryptorchid horses is best performed under general anaesthesia at a surgical facility. Techniques for castration include open, closed and half-closed techniques. Failure of left and right testicles to descend occurs with nearly equal frequency, however, the left testicle is found in the abdomen in 75% of cryptorchid horses compared to 42% of right testicles. Bilateral cryptorchid and monorchid horses are uncommon. Surgical approaches described for the castration of cryptorchid horses include an inguinal approach with or without retrieval of the scrotal ligament, a parainguinal approach, or less commonly a suprapubic paramedian or flank approach. Laparoscopic castration of cryptorchid horses has recently been described but the technique has limited application in practice at this time. A definitive diagnosis of monorchidism can only be made after surgical exploration of the abdomen, removal of the normal testis and hormonal testing. Hormonal assays reported to be useful include analysis of basal plasma or serum testosterone or oestrone sulphate concentrations, testosterone concentrations following hCG stimulation, and faecal oestrone sulphate concentrations. Reported complications of castration include postoperative swelling, excessive haemorrhage, eventration, funiculitis, peritonitis, hydrocele, penile damage and continued stallion-like behaviour.

Surgical repair of a coxofemoral luxation in an alpaca.

A female breeding alpaca with acute lameness of the left hindleg was diagnosed with a craniodorsal coxofemoral luxation. Repair was achieved using extracapsular stabilisation. Two nylon sutures were passed through a hole drilled in the femoral neck and anchored to the dorsal acetabulum using two screws and two spiked washers. A metal crimp was used to tighten and maintain the sutures. Postoperatively the alpaca was confined to a stall for 4 weeks before being returned to a paddock. At 6 months after surgery the alpaca was free of lameness and was successfully mated.

Surgical management of an abdominal abscess in a Malayan tapir.

A captive Malayan tapir was observed to have inappetence, weight loss, signs of depression, mild dehydration and diarrhoea. Haematological and serum biochemical tests showed anaemia, hypoproteinaemia, hyperfibrinogenaemia and neutrophilia with a left shift. Ultrasonic examination of the abdomen under anaesthesia revealed a well-encapsulated abscess. The abscess was marsupialised to the ventral body wall. Culture of the pus produced a mixed bacterial growth. Antimicrobial therapy was based on bacterial sensitivity results. Follow-up ultrasonic examinations showed resolution of the abscess. Ninety-one days after surgery the tapir began regurgitating food and water. An abscess originating from the stomach and occluding the lumen of the duodenum was identified at surgery. The abscess ruptured during surgical manipulations and the tapir was euthanased.

Surgical correction of carpal valgus deformity in three alpacas.

Two alpaca crias and one 14-month-old alpaca were referred for treatment of bilateral carpal valgus. In one cria, hemi-circumferential periosteal transection and elevation combined with an ulna osteotomy was performed initially without success, however transphyseal bridging with screws and wires was used successfully in both crias to straighten the limbs. As the distal radial and ulna growth plates had closed in the 14-month-old alpaca, bilateral wedge ostectomies of the distal radius and transfixation casts were used to straighten and stabilise the limbs. The ostectomy sites healed and the alpaca is ambulatory, although carpal flexion is significantly reduced. Until the relationship between the growth rate of crias and the success of hemicircumferential periosteal transection and elevation and ulna osteotomy is established, transphyseal bridging may provide a more reliable result in crias with carpal valgus deformity and open physes. Wedge ostectomy and application of a transfixation cast can be used to correct severe carpal valgus deformities in alpacas with closed physes.

Survey of the therapeutic approach and efficacy of pentosan polysulfate for the prevention and treatment of equine osteoarthritis in veterinary practice in Australia.

OBJECTIVE: To survey veterinary practitioners in Australia on how they administer pentosan polysulfate (PPS) to horses and their perceptions of the efficacy of PPS for: the prevention and treatment of osteoarthritis (OA), the treatment of OA when PPS is combined with other drugs, and the efficacy of PPS compared with other disease-modifying osteoarthritic drugs. DESIGN: Practitioners were contacted by email, which contained a link to an online survey. RESULTS: A total of 76 responses (34.5%) to the survey were received. Respondents most commonly used PPS as prophylactic therapy prior to competition (80.3%). As a prophylactic agent, PPS was considered by 48.2% of respondents to have high efficacy. The most common dose regimen for prevention and treatment of OA was 3 mg/kg, intramuscularly, once weekly for 4 weeks followed by monthly injections. Most respondents (78%) combined PPS with other drugs for treatment of OA. Intra-articular corticosteroids and hyaluronate (HA) was the most common drug combination used with PPS. PPS was preferred as a prophylactic agent when compared with HA (88.7% vs 11.3%). For treating OA, 83% of respondents considered a combination of PPS, HA and glucosamine to be more efficacious than PPS alone. However, the most common reason not to use this combination was cost (79.1%). CONCLUSION: All respondents used PPS for prophylaxis and/or treatment of OA despite limited published scientific evidence proving its efficacy in horses. Further research is necessary to provide evidence of the clinical efficacy of PPS for the prevention and treatment of OA in horses.

Surgical treatment of osteomyelitis and formation of a sequestrum in the distal metaphysis of the humerus in an alpaca cria.

CASE HISTORY: An 8-week-old, 16-kg alpaca cria was presented with a 2-week history of acute onset of left forelimb lameness. CLINICAL FINDINGS: The cria was weight-bearing but lame at the walk in the left forelimb. There was swelling, heat and pain on palpation of the soft tissues, extending from the mid-shaft of the humerus to the elbow. There was no evidence of a traumatic injury. Radiologically, there was evidence of osteomyelitis and a sequestrum involving the distal metaphysis of the humerus. The sequestrum was removed surgically. No bacteria were cultured from samples taken during surgery. After an initial improvement, the cria became acutely lame, and developed an abscess at the surgical site, which was drained. A pure growth of a strictly anaerobic, Gram-negative, non-spore-forming, pleomorphic, filamentous rod was cultured from fluid from the abscess. Further radiographs suggested a second sequestrum was present, and this was removed surgically. Apart from partial dehiscence of the wound, the cria recovered well, and was sound and without complications 18 months after surgery. DIAGNOSIS: Osteomyelitis and formation of sequestra in the distal metaphysic of the left humerus. CLINICAL RELEVANCE: There has only been one case of osteomyelitis and bone sequestration without evidence of trauma in alpaca crias reported in the literature. However, anecdotal reports by veterinary practitioners described similar cases of osteomyelitis and bone sequestration, usually affecting the long bones. Further investigation of osteomyelitis and bone sequestration in crias is needed, to define the incidence, determine the pathogenesis, and develop specific recommendations for prevention and treatment.

Surgical treatment of osteomyelitis and sequestration of the ilium by a cranial partial hemipelvectomy in an alpaca cria.

A 12-week-old female alpaca cria weighing 10 kg presented with a 2-month history of left hindlimb lameness associated with osteomyelitis and sequestration of the shaft and wing of the left ilium. The affected segment of the ilium was surgically removed. Bacteriological culture revealed a small number of mixed aerobic and anaerobic bacteria. The cria recovered well, was discharged from the hospital 8 days after surgery and was paddock sound without complications 8 months later. Osteomyelitis and sequestration of long bones has been reported in alpacas, but further investigation is necessary to define the prevalence and pathogenesis and to develop specific recommendations for prevention and treatment.