Total pinealectomy by an occipital parasagittal approach in sheep

A reliable method of total pinealectomy in sheep without a resulting significant neurological deficit has been developed and is described. The known effect of light on sheep gonadotropin levels helps validate these studies of its pineal gland. Special attention is given to delineation of the surgical anatomy of the gland and its relationship under magnification to the central draining veins of the brain. In this large mammal this relationship differs considerably from that of humans. The application of an intrahemispheric occipital exposure using magnification, as well as the preoperative administration of steroids and osmotic agents, helped to minimize the effects of retraction and resultant cerebral edema. We have thus been able to increase the rate of successful pinealectomy to 83%, allowing the development of groups of animals suitable for studies of the neuroendocrine function of the pineal and pituitary glands.

Carotid artery exteriorization for percutaneous catheterization in sheep and dogs

Summary and reliable physiologic or pharmacologic investigation in animal models often requires arterial catheterization in awake animal subjects. This can be facilitated by surgical exteriorization of the carotid artery for subsequent percutaneous catheterization. A simplified surgical procedure is described that has been demonstrated to have limited morbidity and excellent applicability for multiple use, as well as to ensure high blood flow rates when needed. The surgical technique involves transfer of the carotid artery from a deep paratracheal position to a ventrolateral neck subcutaneous position, protected from the underlying mattress sutures by the sternomastoid muscle.

Platelet function and coagulation parameters in sheep during experimental vascular surgery

Various clotting parameters (prothrombin time, activated coagulation time, activated partial thromboplastin time, platelet counts, and platelet aggregation) were obtained from unanesthetized sheep and from sheep at various times during 5 hours of vascular surgery. The values obtained were not influenced by anesthesia and surgery and were consistent between sheep. Ovine platelets were less prone to aggregate in the presence of collagen, epinephrine, and ristocetin than those of man. Platelet aggregation induced by adenosine diphosphate was similar to that seen in man. Based on these parameters, the sheep would seem to be a reasonable model for experimental vascular surgery when results are to be applied to man.

Reentrant cannulation of the small intestine in sheep: cannula and surgical method

The function, design and production of a reentrant cannula for the small intestine of sheep and the corresponding surgical procedure are described. The cannula is molded in one piece from polyvinylchloride plastisol. It consists of a curved intestinal tube joined to a stem with an external elliptical ring on the distal end and a perforated flange that encircles the stem above the intestinal tube. A circular perspex valve with two curved channels was made to fit into the interior of the cannula, making it capable of either a "maintenance" or a "collection" function. The cannula was inserted into the proximal duodenum and(or) terminal ileum of sheep via a 5-cm incision on the antimesenteric side of the intestine. The intestine was attached to the cannula by a Dacron straight arterial graft. This reentrant cannulation method does not require an intestinal transection and a mesenteric incision under the transection. Therefore, little damage was done to the blood and nervous system.

Evaluation of the actions and use of alphaxolone/alphadolone (CT1341) in sheep

CT1341 (alphaxolone/alphadolone) (Saffan; Glaxo) at various dose rates was investigated for use as an intravenous anaesthetic agent in sheep and it was found that at least 1.65 mg/kg was required to induce anaesthesia. In an experimental group of animals the effect of CT1341 2.2 mg/kg, on PaO2, PaCO2, paH and mean arterial blood pressure was measured. The drug caused a mild respiratory acidosis accompanied by a slight decrease in PaCO2 tensions. Mean arterial blood pressure decreased by 50 per cent, 30 seconds after injection but this fall lasted for only 10 minutes. Prior administration of either atropine sulphate or mepyramine maleate failed to modify this hypotensive effect. Injection of the vehicle, Cremophor EL, alone had no effect on mean arterial blood pressure. Intracerebroventricular administration of CT1341 while producing anaesthesia failed to produce any hypotension. The drug was used for the induction of anaesthesia in 19 sheep. A mean dose of 3.0 mg/kg was found to be most useful clinically. In a further three sheep an infusion of a dilute solution (0.234 mg/kg per minute) was used to maintain anaesthesia. The most notable clinical feature in sheep was the fast, complete recovery. It is concluded that this agent is an extremely useful drug for the induction and maintenance of anaesthesia in sheep.

Sheep breeding program for the year-round production of timed pregnancies for experimental foetal surgery

Foetal lambs of known gestation were supplied to research programs throughout the entire year by controlling the oestrous cycle of the breeding ewes. In about 55 ewes, an average of 70-3 pregnancies of known duration produced an average of 118 lambs for each of the 3 years (168% of lambs to pregnancies). The accuracy of the ram-marking information, plasma radioimmunoassay (18 days after mating) and ultrasonic flow detection (Doppler; 60 days after mating) as indicators of pregnancy is reported for the last 3 years of this program.

Retractor penis myotomy for catheterization in sheep and goats

Urethral catheterization was successful after retractor penis myotomy in a sheep and a goat, and there were no serious postoperative complications. Sexual behavior and libido were subsequently normal. Tranquilization and epidural nerve block were inadequate for catheterization.

Effect of removal of ovine squamous cell carcinoma on peripheral lymphocyte stimulation by tumour extracts and phytohaemagglutinin

Mock-operation of normal tumour-free sheep was not associated with significant changes in blastogenic responses of peripheral lymphocytes (BRPL) to phytohaemagglutinin (PHA-P) or tumour extracts (TA). In age-matched tumour-bearing sheep, tumour removal was associated with a significant prolonged increase in BRPL to PHA-P and TA about three weeks after operation. This increase was significantly greater in sheep with mature than with early tumours. No increase in BRPL occurred in sheep with secondary lesions. Challenge of tumour-removed sheep with TA 15 weeks after operation was associated with a significant anamnestic-type short-term surge in BRPL to PHA-P and TA, which was significantly greater in sheep which had previously borne advanced tumours. Mock-operated normal mature sheep challenged with TA also showed a lowgrade anamnestic-type response of BRPL to PHA-P and TA. The results are discussed in terms of the mechanisms of BRPL suppression, and of specific reactions in normal sheep.

A technique for sampling total rumen contents in sheep

The paper describes the manufacture of an easily removable large rumen fistula closure for sheep and a restraining cradle which is used when sampling total rumen contents. Eight sheep have been fitted with the fistula and have been used regularly for nine months. The technique is rapid and simple and the closure is more reliable than other types which are often removed accidentally.

A simple technique to establish a self-retaining rumen catheter suitable for long-term infusions

A simple and rapid technique is described for the establishment of a self-retaining permanent catheter in the rumen of sheep. The equipment required is minimal, the procedure takes less than five minutes and causes little disturbance to the animal. The technique has been used successfully on 39 sheep.

Method for repeated or prolonged rumen infusion without establishing an open fistula

A method was developed for repeated or prolonged infusion of substances into the rumen. A blind rumen fistula was surgically formed so that the unopened rumen compartment was easily accessible immediately beneath the skin. A cardiac catheter was inserted into the rumen and was tied to a canvas patch cemented to the animal's coat. This method has been used in cattle and sheep for continuous infusion periods of one to six weeks. This surgical preparation also has been used to put plant material directly into the rumen and to obtain rumen contents. Thus, a large number of fistulated animals can be maintained over long periods without the disadvantages of maintenance required for animals each having an open fistula fitted with a closure device.

A surgical technique for the collection of cervical mucus in the ewe

A technique for collecting cervical mucus in ewes is described. By a surgical procedure, the cervix was fixed to the ventral abdominal wall to enable mucus to be collected continuously into a container attached to the ewe. Mucus was collected successfully by this method for up to 14 months.

Surgical transfer of the cysticerci of Taenia hydatigena

Unattached immature cysticerci of Taenia hydatigena were transferred surgically to the peritoneal cavities of 4 sheep. Mature infective cysticerci were recovered from the recipient sheep 3 and 5,8 months later. A fully developed live cysticercus was present in the muscle layers surrounding the scar of the laparotomy site in 2 of the animals.

Effects of experimental excision arthroplasty of the hip joint

The experimental results are reported on a series of sheep in which unilateral hip excision arthroplasty was performed. These sheep were slaughtered at regular postoperative intervals. Radiography and histology were performed on the normal and excised hip joints of the experimental sheep to provide information of the formation of the pseudarthrosis that develops following excision arthroplasty. The efficiency of the false joint that develops is good, judged on a clinical basis. Continuous remodelling of the acetabulum and resected face was noted throughout the experimental period. A sequence of degenerative changes in the acetabular cartilage was observed followed by filling in of the acetabular favity with new bone. New bone also developed on the cemoral component of the pseudarthrosis in the form of osteophytes situated around the perimeter of the resected surface. Growth deformities of the contralateral, nonoperated limb were induced.

Technique for sampling subcutaneous fat from the tailhead of sheep

Previously reported fat biopsy techniques (either omental or subcutaneous) require extensive restraint of the animal, require anesthesia methods, are time-consuming to do, or demand much postoperative care. The biopsy technique reported in the present paper involves the subcutaneous fat located around the tailhead of sheep. With minimal restraint of the sheep and local anesthesia, up to 1 g of subcutaneous fat can be obtained using this surgical procedure. Michel clips facilitate closure of the surgical wound, making this method brief in operative time.

Ureterocolostomy. An antireflux technique

A new antireflux ureterocolonic urinary conduit was developed and evaluated in sheep. It combined the principles of the Wallace conjoined ureterointestinal conduit with the Lich extravesical ureteroneocystostomy. The procedure accomplished the following with a single anastomotic technique: (i) joined both ureters to the intestinal stump; (ii) provided constant ureteral orifice position in the antimesenteric butt of the intestinal segment; (iii) eliminated the blind intestinal stump; (iv) prevented intestinoureteral reflux; and (v) allowed an average of 12 times the normal urinary flow rate before exceeding mean human midureteral peristaltic pressure. The projected long term animal experiments and the sound urologic surgery principles involved indicate that the procedure may soon have clinical application.

The effects of various forms of gastrointestinal cannulation on digestive measurements in sheep

1. There was little difference in digestive (voluntary food intake, dry matter digestibility and nitrogen balance) and blood measurements (venous concentrations of corticosteroids, serum aspartate aminotransferase (EC 2.6.1.1), protein-bound iodine, urea and glucose) of intact sheep (eight animals) and of sheep prepared with rumen cannular (sixteen animals) and subsequently with either simple 'T-shaped' (eight animals) or re-entrant cannulas (eight animals) at the duodenum and ileum, when fed ad lib. a chopped medium-quality-hay ration. 2. Wool growth rates of the intact sheep were similar to those in sheep with rumen cannulas and with rumen cannulas plus simple 'T-shaped' cannulas, but higher (P less than 0-01) than those with rumen cannulas plus re-entrant cannulas. 3. When the sheep were subsequently given a restricted intake (800 g/d) of dried grass, retention times of solid- and liquid-phase digesta markers in the rumen and caecum were similar in all sheep. 4. The use of the different preparations in digestive physiology studies is discussed.

Effects of starvation, surgery and infusion of adrenocorticotrophin on plasma amino acid concentration in the pregnant ewe

Total plasma amino acid concentrations (TAA) in 12 Scottish Blackface ewes between 80 and 140 days of pregnancy were unaltered by two days of starvation, but concentrations of essential amino acids (EAA) increased and non-essential amino acid (NAA) levels decreased. These trends were more pronounced later in pregnancy. Ewes fasted before surgery to implant fetal catheters showed marked reductions in mean TAA levels (--26 per cent, n-5) on the day after operation (day+ 1). Half of this decrease was accounted for by glycine. Mean concentrations of NAA increased after day +1 but by day +6 were still 15 per cent below baseline values. In contrast mean plasma concentrations of EAA were 31 per cent above prestarvation levels on day +6 and maximal on day +4(+39 per cent). Following a two-day fast, sheep given half rations and simultaneously infused with adrenocorticotrophin showed changes in plasma-free amino acid composition like those observed during the two days after operation. Disturbances to plasma amino acid concetrations persisted for up to 12 days after operation and are attributed to the preoperative starvation and the combined effects of irregular feeding patterns and elevated plasma corticosteroid levels during and after operation.

Twelfth rib resection as an approach for portal vein cannulation in sheep

A surgical technique involving resection of the twelfth rib was used to insert silastic cannulas into the portal veins of three sheep to study amino acid metabolism. Good exposure to the vein was achieved by this method although it required positive ventilation due to the penetration of the thoracic cavity. All cannulas were buried subcutaneously and exteriorized near the dorsal midline. This facilitated continuous infusion into the portal cannula without disturbing cannula placement.

Homogeneous joint transplantation in sheep

An experimental study on the homogeneous transplantation of the major part of the lateral and medial femoral trochleae and trochlear groove with articular cartilage was carried out in the School of Veterinary Medicine, Pahlavi University, Shiraz. The results of postoperative clinical examinations and regular radiographical observations are described. Finally, the pathological findings and surgico-pathological observations are noted. The advantages of using the technique described and its possible clinical applications are discussed.