THE DIAGNOSIS AND EPIDEMIOLOGY OF AN INFERTILITY DISEASE IN THE FEMALE KOALA

A radiographic technique, incorporating pneumoperitoneum, was developed to aid in identification of cyst-like structures in the reproductive tract of female koalas. These lesions, including pyometra and fluid-filled cysts associated with the upper reproductive tract, were viewed as radiopacities with clearly demarcated margins lateral to the caudal lumbar vertebrae. This technique provided a means of assessing with a high degree of reliability the incidence and distribution of this condition in various populations of koalas throughout eastern and southern Australia. A radiographic survey of 237 adult female koalas revealed a 43% (101/237) incidence of this condition, which is closely correlated with the lack of reproductive success observed in some populations of koalas in the wild. Although the etiology of this condition is little understood at present, the isolation of Chlamydia psittaci from the reproductive tracts of affected koalas, both male and female, is recorded.     

Surgical Correction of Congenital Bilateral Choanal Atresia in a Foal

Congenital bilateral choanal atresia was corrected surgically in a neonatal foal. Presenting clinical signs included complete obstruction of the upper airway, which had been relieved by tracheotomy. The diagnosis was confirmed by endoscopic examination and contrast radiography. Bilateral nasal flaps were used to gain access to the caudal nasal cavity, allowing removal of obstructive tissue and restoration of normal respiration. Malocclusion developed secondary to surgical intervention and resultant damage to suture lines of developing flat bones of the skull. Nine months postoperatively, the asynchronous growth of the mandible and maxilla had not resulted in difficulty during mastication. Respiration, although audible during periods of exercise, was acceptable to the owners.     

A METHOD OF MOUNTING A GAMMA DETECTOR AND YOKE ASSEMBLY FOR EQUINE NUCLEAR IMAGING

A scintillation detector assembly capable of providing the range of movement and flexibility needed for the investigation and diagnosis of equine-related health problems was required for the nuclear medicine facility of the Equine Research Centre, Guelph, Ontario. The planning, technique and modifications used to mount the gamma detector and yoke assembly are detailed herein. The system has been successfully used for the nuclear scans in horses, and demonstrates the practicality, safety and usefulness of equipment adaptation for large animal imaging.     

Timing of induction of ovulation in mares treated with Ovuplant or Chorulon

Reliable induction of timed ovulation is an important managerial tool in any horse-breeding operation. Not only does breeding close to ovulation increase pregnancy rates when using cooled, frozen, or poor-quality semen, but it also reduces the number of inseminations needed per cycle, resulting in a more efficient breeding program. To better predict ovulation time in the long estrus period of the mare, one could increase the frequency of transrectal palpations and ultrasounds and/or implement hormonal therapies to induce ovulations. However, previous studies have been unclear on the exact timing of ovulation of mares treated with human chorionic gonadotropin (Chorulon, Intervet Inc, Millsboro, DE) or deslorelin acetate (Ovuplant, Pharmacia and UpJohn Co, Kalamazoo, MI). This study was designed to determine the timing of ovulation after Ovuplant or Chorulon treatment in normal cycling mares presented to the veterinary clinic. In addition, the pregnancy rates were determined for mares bred when a single insemination, using frozen or chilled semen, was performed at a fixed time (36 hours) after Ovuplant or Chorulon treatment. Thirty-two mares were given a subcutaneous injection of 7.5 mg of prostaglandin F2α (Lutlyse, Ft Dodge Animal Health, Ft Dodge, IA) 5 days after the last ovulation and were examined every 48 hours until estrus was detected based on a dominant follicle and the presence of endometrial edema as determined by ultrasonographic examination. Group 1 (N = 12) was treated intravenously with 2,500 units of Chorulon, and group 2 (N = 20) was treated subcutaneously with Ovuplant as soon as mares were determined to be in estrus. Once treated all mares were examined by rectal palpation and ultrasound at 0, 12, 24, 28, 30, 32, 34, 36, 38, 40, 42, 44, 48, 60, 72, 84, 96, hours or until ovulation was detected. Ovulation rate in response to Chorulon was 83.3% at 48 hours, 91.6% at 72 hours, and 100% at 96 hours. All of the mares in the Ovuplant-treated group had ovulated by 48 hours. Chi-square analysis of the data showed a significant (P < .01) variation in the distribution of ovulation times between mares treated with Chorulon and mares treated with Ovuplant. This study provides enough evidence to support the hypothesis that timing of ovulation is a more reliable event in mares treated with Ovuplant compared with those treated with Chorulon.     

The use of the nondepolarizing neuromuscular blocking drug cis-atracurium in dogs

Objective This clinical trial attempted to evaluate the potency, onset and duration of action of cis‐atracurium in dogs. Animals Twenty dogs aged between 1 and 15 years and weighing between 15 and 85 kg admitted for a variety of elective, surgical procedures under general anaesthesia. Materials and methods Following induction of general anaesthesia, the effects of an intravenous loading dose of cis‐atracurium (0.1 mg kg^?1) were evaluated by counting visual responses to train of four (TOF) nerve stimulation. Incremental doses of 0.02 or 0.04 mg kg^?1 cis‐atracurium were administered when the first of four responses to TOF stimulation was present. Results An initial dose of 0.1 mg kg^?1 eliminated all four TOF responses in 18 out of 20 dogs. The same dose, repeated 10 minutes later in two animals in which blockade was incomplete, abolished all responses. In dogs receiving 0.1 mg kg^?1 cis‐atracurium neuromuscular blockade lasted 27.2 ± 9.3 minutes. Up to six incremental doses were given in individual animals; incremental doses appeared to be noncumulative. No untoward side‐effects were observed with the use of this drug. There was considerable variation between individuals in response to cis‐atracurium. Conclusions Cis‐atracurium is an effective neuromuscular blocking agent in the dog, although its potency varies. Clinical Relevance Further studies are required to determine whether observed differences in potency are related to age, breed or sex. Cis‐atracurium may prove useful in dogs with impaired renal and or hepatic function.     

Anaesthesia with ketamine/medetomidine in the rabbit: influence of route of administration and the effect of combination with butorphanol

Objective To compare the characteristics of anaesthesia induced with ketamine/medetomidine administered by the subcutaneous and intramuscular routes and to assess the effects of the addition of butorphanol to this combination. Study design Prospective randomised study. Animals Six female New Zealand White rabbits. Methods Rabbits were given one of four combinations of ketamine and medetomidine (K/M) either subcutaneously (SC) or intramuscularly (IM) on four successive occasions with a 7‐day interval between treatments. The dose combinations were; 15/0.25 mg kg^?1 SC; 15/0.25 mg kg^?1 IM; 15/0.5 mg kg^?1 SC, and 15/0.25 mg kg^?1 together with 0.4 mg kg^?1 butorphanol (K/M/B) SC. The effects of anaesthesia on arterial blood gas values and cardiovascular variables were recorded at predetermined time points. Toe and ear pinch reflexes were judged to determine the duration of surgical anaesthesia. Loss of the righting reflex was used to measure the duration of sleep time. Analyses used repeated measures analysis of variance. Results All groups lost the righting reflex and ear pinch response. Three animals in the groups that received K/M alone lost their toe pinch reflex, whereas four lost this reflex when given K/M/B. Time of onset of loss of the righting, toe and ear pinch reflexes did not differ significantly among the groups. The higher dose combination of medetomidine with ketamine and the combination of K/M/B produced a greater duration of loss of the ear pinch response than the lower dose of K/M administered by either route. No significant differences were found among the groups in the duration of loss of the toe pinch reflex. All animals developed a moderate bradycardia (mean heart rate <166 beats minute^?1) and moderate hypoxaemia (mean P_aO₂ < 6.0 kPa). Animals given butorphanol showed the greatest reduction in respiratory rate (31 ± 13 breaths minute^?1, p < 0.05) but this was not reflected in any significant differences in arterial PCO₂, PO₂ or pH among the groups. Conclusions Administration of K/M by the SC route produced equivalent effects in comparison to intramuscular administration. The addition of butorphanol increased the duration of anaesthesia, but produced a slight increase in the degree of respiratory depression. All dose rates resulted in hypoxaemia so oxygen should be administered when these combinations are used in rabbits. Clinical relevance Subcutaneous administration is both technically simpler and may cause less discomfort to the animal than IM injection, and so is preferred. The combination of K/M with butorphanol has relatively minor effects on the depth and duration of anaesthesia, so offers little advantage to the use of K/M alone.