Mark Corson

By A. Arokkh. Patrick Henry College. 2018.

In birds with moderate numbers of In some species (magpie and starling) 0.1 combipres overnight delivery, massive shed- megabacteria cheap 0.1 combipres with amex, the pH of the proventriculus ranged from 1 combipres 0.1 on line. Proventricular and Ventricular Nematodes Many nematode species have been reported to occur The proventriculus in an ostrich is a large, thin- in the proventriculus (Echinura uncinata, Gongy- walled structure. The distal extremity of the ostrich spirura spinosa and Epomidiostomum uncinatum proventriculus passes dorsal to the ventriculus and are found under the horny layer of the ventriculus empties on the caudal aspect of this organ. Clinical signs may triculus is large, which makes it easy to remove be absent or include emaciation, anemia and mortal- foreign bodies from the ventriculus through a ity. Treatment proventriculus is large and spindle-shaped, and the can be attempted with levamisole (20 mg/kg orally, or ventriculus is slightly larger and more lightly mus- 10 mg/kg parenterally) or ivermectin (200 µg/kg par- cled than that of the ostrich. It should be stressed that experience with ivermectin in many avian species is absent. Acute death has been reported after the use of ivermectin in some mammalian and reptilian species. The descriptive term myenteric ganglioneuritis and encephalo- myelitis of Psittaciformes best defines the following histologic lesions that can be observed in affected animals: lymphocytic and monocytic infiltration of intrinsic and extrinsic splanchnic nerves of the muscularis tunics of the alimentary tract; in some cases, leiomyositis in or- gans innervated by affected nerves and non-suppura- tive encephalitis, myelitis and radiculoneuritis have been described. In advanced cases, proventricular dilata- tion can be visualized on abdominal radiographs, with or without contrast media (Figure 19. Note Proventricular dilatation disease the numerous filling defects (ingesta and undigested seeds) in the crop, proventriculus and intestines. The client chose to have the Proventricular dilatation syndrome bird euthanatized. Histopathology confirmed a diagnosis of Macaw fading syndrome neuropathic gastric dilatation. Vitamin E and selenium deficiencies Gastric Impaction and Gastric Foreign Bodies Gastric impaction is common in psittacine babies can be confirmed by histologic identification of char- that consume bedding material such as crushed wal- acteristic lesions in the splanchnic nerves from a nut shell, ground corncob, shredded paper pulp, sty- ventricular biopsy (Figure 19. Affected of intranuclear and intracytoplasmic inclusion bod- 26,63,84,123 animals were emaciated and had empty intestinal ies in affected tissue of some birds. Those fed late in the including supportive care, a liquid diet, vitamin sup- day are less likely to retain their casting. It has been suggested that In ostriches, (pro)ventricular impaction is a serious birds can survive on a liquid diet,78 but no case re- 209 management problem. Most affected birds are under six months of age, caution, given that the disease may be caused by an but the condition can also occur in adults. Cloacal pro- It has been suggested that a virus may induce an lapse may occur in young birds several days to four autoimmune reaction that would be responsible for 67 weeks old. The inciting virus tion and radiographs followed by immediate surgical would no longer be present when the disease became correction are imperative for successful resolu- clinically obvious or was diagnosed at necropsy. Contrast studies indicated a delayed gastric-emptying time, hepatomegaly (causing the proventriculus to be displaced dorsally) and retention of barium in the proventriculus, suggestive of mucosal inflammation. Barium contrast radiographs were used to confirm that the string of beads passed into the small intestines. Gastritis, Heavy Metal Poisoning Radiographs indicated that the ventriculus was full of metallic densities. Because the wire was composed of a ferrous metal, a) the foreign bodies were removed by repeatedly inserting Ingestion of metallic foreign bod- a red rubber feeding catheter equipped with several neodymium-ferro-borium alloy magnets ies is relatively common in Galli- (arrows). Paralysis of the intestinal tract Foreign body penetration of the ventricular wall from nerve damage may occur secondary to lead causes a decrease in ventricular contraction and an poisoning. In Anseriformes, this is clinically recog- insufficient digestion of food, which may be recog- nized as esophageal and proventricular dilatation. In nized clinically by the passage of undigested seeds in the other orders, ingestion of ferrous metal objects, the feces. In the racing pigeon, passing undigested such as nails, wire, hairpins and needles, account for seed is considered pathognomonic for a traumatic the majority of cases. Noninvasive treatments for removal of gastric metal Ingestion of ferrous objects may cause perforation of foreign bodies should be attempted before (pro)ven- the ventriculus (majority of cases) or proventriculus, triculotomy. Ferrous metals may be removed from leading to an acute, generalized, purulent peritonitis the (pro)ventriculus using a powerful magnet of neo- or to a local peritonitis with abscess formation on the dymium-ferro-borium alloy (The Magnet Store 1- serosal surface of the (pro)ventriculus or duodenum. The size of the polyvinyl probe and 200 mmHg, which can easily force sharp objects magnetic disk can be varied according to the size of through the tough muscular wall. A probe with a length of two meters, a tration of a large (hepatic) artery or vein can result diameter of 18 mm and an attached cylinder magnet in fatal hemorrhage. In some rare cases, the ferrous of 17 x 70 mm (derived from a bovine cage magnet) foreign body will be resorbed by the inflammatory has been used to remove thirteen large staples from reaction without permanent deleterious effects. Myoventricular Dysgenesis Proventricular dilatation secondary to ventricular abnormalities caused by feeding finely ground food low in fiber is commonly observed as an in- cidental finding in chickens. The ventriculus in affected birds is poorly developed, and there is no sharp demarcation between the proventriculus and ventriculus. Vitamin E and Selenium Deficiencies Vitamin E and selenium deficiencies may cause de- generative lesions in the smooth muscle of the ven- triculus of domestic and free-ranging Anserifor- mes. Many affected animals are “high strung” or in what could be called stressful environments (Fig- ure 19. High dietary levels of certain types of fish meal or finely ground, low-fiber diets can cause erosions and ulcers in the koilin layer of gallinaceous birds. Contrast radiographs indicated mucosal fill- Copper Poisoning ing defects in the proventriculus.

Three species are found on nominate species are characterized by fine stellate New Guinea; one also ranges in northern Australia combipres 0.1 with amex. Cassowaries are solitary buy 0.1 combipres otc, the males are highly ag- gressive and these birds adapt poorly to most captive S quality 0.1 combipres. The neck and thighs of the male 5 nian and Kangaroo Island emus became extinct only are gray and the head is feathered. Adult emus may weigh 55 kg and in the shells of this subspecies leave the egg with a stand 1. The careful breeding of this bird since the 1870’s has Other Ratites resulted in a smaller, calmer bird that has higher quality feathers than its free-ranging relatives. Both groups are specialized Ostriches can run up to 40 mph for several miles and ground-dwelling birds that bear little resemblance can kick forward with powerful and accurate blows. This chap- Ostriches have large eyes with substantial visual ter will focus primarily on the ostrich as the model acuity, and large ear canals with a keen sense of ratite, with only occasional comment on the emu, hearing. The deviations from this model, including their size, are all adaptations to a terrestrial lifestyle. The similari- ties and differences are clinically relevant and should be familiar to the ratite veterinarian. In addition, the ostrich has a callosity distal to the pubic bone and another distal to the hock joint; both anatomic areas contact the ground in a recumbent bird. Apteria are present along the lateral body wall and provide convenient access sites for surgery and diagnostic procedures such as ultrasound. In contrast to other birds, the feathers of the ostrich function to shade the body, rather than insulate it, and an ostrich will erect the feathers when hot and flatten them when cold. Musculoskeletal System The rhea, emu and cassowary have three toes (digits 2, 3 and 4), each with four phalanges. The ostrich is the most specialized runner and has only two toes (digits 3 and 4); the metatarsal-phalangeal joint is suspended so that the standing weight is born en- tirely by the digits (Figure 48. The pubic bones of the ostrich form a solid ventral symphysis to support the weight of the abdomen (Figure 48. Because there is no need for flight, the thoracic sus 2) metatarsal phalangeal pad 3) digital cushion 4) phalangeal pad 5) toenail (modified with permission from Murray Fowler19). In the ostrich and emu, one of the tarsal bones remains unfused to the contiguous bones, which should not be misinterpreted as the knee radiographically. A surgical incision made along the midline penetrates the skin, sub- cutaneous fat (minimal) and a dense fibrous abdominal tunic. The next layer is retroperitoneal fat, which may be two to eight centimeters thick, especially in the emu. When a laparotomy is performed, the bulk of this adipose tissue should be peeled away prior to closing the body wall (Color 48. Respiration occurs by lateral excursions of the chest wall, which must be considered during an- esthesia and recovery. The normal respiratory rate in adult ostriches is 6 to 12 bpm, which may increase to 40 to 60 bpm during periods of stress, exercise or with high temperatures. The lungs and air sacs are similar to those of other avian species, but the air sac capacity is greatly reduced. The distinct visceral outlines created by the air sacs in the radiographs of psittacines are not present in ratites. Other structures of interest include the first rib (r), The femur is the only pneumatized cartilaginous extension of the sternum (c) and the humerus (h). Other structures include the femur (f), ilium (s), ischium (i) and pubic symphysis (t) Emus have a longitudinal cleft in the (courtesy of Murray Fowler,19 reprinted with permission). This insertion of the muscle on the cnemial crest of the area is particularly well developed in the female. The crest is projected craniodorsally pro- the chick, a thin membrane covers the cleft. Material deposited into the esopha- gus during tube-feeding is routinely regurgitated, creating a risk for aspiration. Consequently, gavage feeding requires that a tube extend into the proven- triculus. The proventriculus of the ostrich is a large, dilated, thin-walled structure that is easy to access surgically because it extends caudal to the ventriculus (Figure 48. In most avian species, the entire inner surface of the proventriculus secretes digestive enzymes. In contrast, the secretory region of the ostrich proven- triculus is restricted to an area of glandular tissue on the greater curvature. The distal extremity of the ostrich proventriculus passes dorsal to the ventricu- lus and empties into this organ through a large open- ing on its caudal aspect. Ventricular foreign bodies can be easily removed through an incision made into the proventriculus. The ventriculus is situated slightly to the left of the midline at the caudal border of the sternum. Though the proven- triculus and ventriculus can normally contain small stones, gastric impaction from the consumption of foreign bodies is a common problem in ratites, par- ticularly in juvenile birds (Color 48. In emus rected into the pouch causes a drumming sound in the female and a growling sound in the male. The presence of this expandable pouch may compli- cate inhalation anesthesia in mature emus. If posi- tive pressure ventilation is used to inflate the air sacs and ventilate the lungs, air may be directed into and thus inflate the pouch.

Overview of the Procedures The nuclear transplantation procedures were pioneered in 1952 in R trusted 0.1 combipres. The donor cells were most conveniently handled in suspension following trypsinization best combipres 0.1. The donor cells were drawn into a glass micropipet buy generic combipres 0.1 on line, then inserted into the enucleated egg between the center and the animal pole. The intact donor cell, with its nucleus, cytoplasm, and membranes, was expelled into the recipient egg. The membranes surrounding the recipient cell should heal spontaneously as the pipet is withdrawn. The eggs were then transferred to buffered media and cleavage proceeded as manipulation of the oocyte was suf- ficient activation stimulus in amphibians. Nuclear transplantation procedures in mammals involve four specific steps: (1) enucleation, (2) transfer of a donor nucleus along with its associated cytoplasm, (3) fusion of the donor nucleus and recipient cytoplasm, and (4) activation of cleavage (Fig. Enucleation is accomplished by inserting a glass micropipet through the zona pelucida and withdrawing the polar body and metaphase chromosomes. Rather than direct injection, the intact donor cell (nucleus, cytoplasm, and mem- branes) is expelled into the perivitelline space adjacent to the enucleated oocyte with the aid of a micropipet. The enucleated oocyte and intact donor cell are then fused and treated to initiate the cell cycle, which is referred to as activation. A donor cell (nucleus and cytoplasm) is transferred to the perivitelline space using a micropipet. Electrical pulses are used to stimulate fusion of the plasma membranes of the donor cell and recipient cytoplast causing the donor nucleus to enter recipient cytoplasm and initiation of cell division. If successful, the embryo will continue to undergo cleavage to form a normal blastocyst. Fusion The first challenge was to develop more versatile methods for fusion of the donor and enucleated recipient cells. The use of Sendai virus to mediate fusion of the recip- ient oocyte and donor cells was ineffective in a number of species. The advent of electrical fusion of cell membranes provided a flexible and efficient method to stimulate fusion of the donor and recipient cells in a broad range of species. Treatment with cytoskeletal inhibitors, cytochalasin B, and colcemid stabi- lized the plasma membrane and prevented rupturing. This allowed a large pipet to be inserted through the zona pellucida and adjacent to the pronuclei without pen- etrating the membrane. The pronucleus can then be removed in a membrane-bound cytoplast along with the polar body as shown in Figure 2. Activation following nuclear transplantation also proved to be a formidable problem and variable among species. This may belie the lower efficiencies associated with nuclear transplantation in rodents. In cattle, fer- tilization of oocytes by sperm was shown to initiate changes in calcium concen- trations in the oocyte cytoplasm. The electrical pulses used to induce fusion were also shown to cause calcium increases but were minimally effective in activating the oocyte following nuclear transplantation. Cell Cycle Synchronization Between Nuclear Donor and Recipient Oocyte Synchrony of the cell cycle between recipient oocyte and donor nucleus was also subject to refinements. Although modest success has been achieved, this approach remains technically challenging. The difficulty in using G2 or M-phase donor cells is that the cells are tetraploid at this stage of the cell cycle. Therefore, cell division must occur following nuclear transfer to produce a diploid two-cell embryo. This sequence of events may be crucial for nuclear proteins of the donor cell to be lost and replaced by the oocyte nuclear proteins with nuclear reformation allowing reprogramming of the chromatin. An initial report of successful nuclear transplantation in mice offered promise but was unable to be confirmed by other investigators. Blastomeres as Nuclear Donors In sheep, blastomeres from 8-cell and 16-cell embryos were shown to develop to blastocysts following nuclear transplantation and form viable embryos after trans- fer to the oviduct of recipient ewes. This was the first reproducible evidence that mammals could be cloned by nuclear transplantation as reported in Nature in 1986. Cattle (1987) and rabbits (1988) were soon added to the growing list of mammals that had been cloned with the assistance of nuclear transplantation. Full-term devel- opment of mice from nuclear transfer of blastomeres was eventually demonstrated in 1987. However, the rates were low compared to sheep and cattle, possibly due to differences in the requirements for activation following nuclear transfer. These results emphasize the considerable variation in the success in cloning mammals using blas- tomeres as donor cells. Unlike earlier results using nonmammalian species, serial nuclear transplantation did not offer any substantial improvement in developmen- tal potential. Nonetheless, results from mice, rabbits, and cattle all suggest that reprogramming of cellular fates is dramatically restricted in eight-cell embryos and beyond. The prevailing wisdom was thoroughly shaken by the reports of Dolly—a normal sheep that developed to term following nuclear transplantation of a donor nucleus from a single mammary epithelial cell. Not only was Dolly cloned from somatic cells but it was from adult cells providing a dra- matic confirmation of the earlier work of Gurdon (1970). This was followed by nuclear transplantation of embryonic fibroblasts to clone cattle, sheep, and goats. Cumulus cells from adult animals have also been used as donor cells to clone mice and cattle.