Dennis D. Caywood

Canine Pancreatic Endocrine Tumors: Immunohistochemical Analysis of Hormone Content and Amyloid

Thirty-one primary canine pancreatic endocrine tumors and their metastases were studied histologically and immunohistochemically for the presence of insulin, glucagon, somatostatin, pancreatic polypeptide (PP), gastrin, and adrenocorticotrophic hormone (ACTH). Tumors were also evaluated for the presence of amyloid. The cytoarchitectural pattern of 25 of 31 primary tumors was predominantly solid, whereas three tumors were mostly glandular, two were unclassified, and one had a gyriform pattern. Cells with insulin immunoreactivity were found in 30 of 31 tumors and were found in all cases in which there was clinical evidence of inappropriate insulin secretion. Insulin was the only hormone demonstrable in three of the 30 tumors, but cells immunoreactive for other hormones were also present in various combinations in most tumors [i.e., glucagon (13 of 30), somatostatin (17 of 30), PP (25 of 30), and gastrin (2 of 30)]. One tumor contained only cells with glucagon and PP immunoreactivity. Amyloid was found in ten of 31 primary tumors but was not detected in metastases. Cells with insulin immunoreactivity were the only cell type consistently present in tumors containing amyloid. Amyloid deposits did not immunoreact with any of the antisera. Seventeen of 31 dogs had metastasis of the pancreatic endocrine tumor to regional lymph nodes, liver, or both. All metastases available for study (15 of 17) contained cells with insulin immunoreactivity and some contained cells with PP or somatostatin immunoreactivity. No statistically significant (P > 0.05) differences in tendency to metastasize were found when pancreatic endocrine tumors were compared by region of origin, cytoarchitectural pattern, presence of amyloid, or by number of hormones contained within the tumor.

Immobilization increases bone prostaglandin E: Effect of acetylsalicylic acid on disuse osteoporosis studied in dogs

The effect of acetylsalicylic acid (aspirin) on bone mass and bone prostaglandin E (PGE) in immobilization osteoporosis was studied in 12 growing dogs using a unilateral hind limb cast-fixation model. Osteoporosis was induced by fiberglass-cast immobilization of the right hind limb for 4 weeks, with the left hind limb as a control. Six dogs received buffered aspirin at 25 mg/kg body weight per os every 8 hours; 6 dogs received no treatment. All the dogs were killed after 4 weeks, and bone samples were collected. Bone mineral content of the distal tibial metaphysis was measured by single-photon absorptiometry. In vitro release of PGE from the calcaneus, tibial cortical bone, tibial cancellous bone, and ilium were measured using a specific radioimmunoassay for PGE. Compared with the controls, the casted limb of untreated dogs had half the bone mass and a twofold increase in bone PGE. Aspirin treatment was associated with a 65 percent reduction in bone PGE and a 13 percent bone mass sparing effect. These results provide indirect evidence that PGE plays a role in immobilization osteoporosis.

Resolution of Superficial Necrolytic Dermatitis Following Excision of a Glucagon-Secreting Pancreatic Neoplasm in a Dog

An 11-year-old, neutered male standard poodle was diagnosed with superficial necrolytic dermatitis and a glucagon-secreting pancreatic islet neoplasm based on clinical, biochemical, histopathological, immunohistochemical, and hormonal findings. Hyperglucagonemia, hyperinsulinemia, and hypoaminoacidemia were observed on preoperative laboratory analysis. Abnormal laboratory values returned to normal, and complete resolution of skin lesions occurred after tumor excision. The dog has remained clinically normal for six months following surgery.

Variation in the pathogenic potential and molecular characteristics of bovid herpesvirus-4 isolates

Seven bovid herpesvirus-4 (BHV-4) isolates recovered from various clinical conditions of cattle were studied for their pathogenic potential in pregnant rabbits. These viruses were originally recovered from respiratory and reproductive tract infections of cattle. A virus dose of 4 x 10(6.8)TCID50 per fetus was inoculated via the intrauterine route in 10- and 17-day pregnant rabbits. Clinical, virologic, and pathologic data were collected to compare the effect of each isolate on does and fetuses/kits. Three isolates (LVR-140, QVR-3140 and 86-068) caused abortion, fetal reabsorption and/or mummification in inoculated rabbits. Virus was recovered from tissues of inoculated rabbits (especially the spleen, ovaries and uterus) by organ explanation and/or co-cultivation. Intravenous inoculation of isolate 86-068 did not produce any clinical signs in either 10- or 17-day pregnant rabbits. All seven isolates of BHV-4 showed a predilection for the reproductive tract of pregnant rabbits but varied in the severity of disease signs produced. Variation was also observed in the genome of various isolates on the basis of restriction endonuclease (RE) analysis. Relationship of RE patterns to the variation in the pathogenic potential of seven BHV-4 isolates is discussed.

Surgical removal of canine uroliths.

Surgery is indicated for patients with obstructive uropathy; calcium oxalate, calcium phosphate, silica, and perhaps cystine uroliths; uroliths refractory to medical dissolution; nephrolithiasis and progressive renal dysfunction; anatomic defects predisposing to urinary tract infection; and problems precluding medical management. The goals of surgical management include removal of all uroliths while preserving organ function, eliminating partial or complete obstruction to urine outflow, and correction of anatomic abnormalities that predispose the patient to infection and or urolithiasis.

Surgical Reconstruction of Partial Circumferential Esophageal Defect in the Dog

Partial circumferential reconstruction of the cervical esophagus was evaluated in the dog. An esophageal defect 5.85 +/- 1.15 cm in length involving one-half of the circumference was repaired by direct closure (group I), using longus colli muscle patch grafts (group II), and using grafts of longus colli muscle lined with buccal mucosa (group III). The incidence of leakage, fistula formation, luminal stricture, peristalsis disturbance, lining loss, the quality of surface restoration, bursting strength, and wound healing were evaluated. No fistula formation or leakage was observed in any animal. Direct closure of the defect was easier to perform, led to less inflammatory reaction, and resulted in the highest bursting strength. However, this method was associated with luminal stricture and swallowing difficulties. The longus colli muscle patch grafts (group II) were associated with a slight to moderate luminal stricture, but had more inflammatory reaction and graft surface area contraction (62%) compared to group III. The longus colli muscle lined with buccal mucosa caused no stricture and slight surface area contraction (8%). Mucosal grafts remained viable and no lining loss was observed. Despite the loss of peristalsis at the level of the graft in 25% of the group III dogs, no clinical signs or swallowing difficulties were observed.

Feline perineal urethrostomy

Perineal urethrostomies are associated with complications that may mimic primary causes of feline lower urinary tract disorders. Though postoperative urethral strictures may be minimized by proficiency with an effective surgical technique, removal of the distal urethra may result in bacterial urinary tract infections in 25% to 30% of patients after surgery. Urinary tract infections caused by urease-producing microbes may induce struvite urolith formation. Thus the prophylactic benefits of minimizing recurrent urethral obstruction by urethrostomy must be weighed against a long-term predisposition to recurrent bacterial urinary tract infection and urolith formation.

Closed aortic valvotomy: a retrospective study in 15 dogs

The results of closed, transventricular valvotomy in 15 dogs with subvalvular aortic stenosis (SAS) were evaluated in a retrospective study. Fourteen dogs ranged from five to 10 months of age; one dog was 42 months of age at the time of surgery. A combination of physical examination, thoracic radiography, electrocardiography, echocardiography, Doppler ultrasonography, and cardiac catheterization was used to establish a definitive diagnosis. Of the 15 dogs undergoing surgery for SAS, 13 had both two-dimensional (2-D) and M-mode echocardiographic examinations; three had successful Doppler aortic blood-flow studies; and five had successful cardiac catheterizations with selective ventricular angiography and intracardiac pressure measurements. In the five dogs undergoing preoperative catheterization, pressure gradient measurements across the aortic valve ranged from 58 to 130 mm Hg. Gradients were reduced by 55% (from 58 to 26 mm Hg), 54% (from 65 to 30 mm Hg), and 30% (from 93 to 65 mm Hg) in three dogs measured postsurgically at 2.5 months (n = 2) and four months (n = 1), respectively. The 10 surviving dogs that were available for follow-up were free of clinical signs of cardiac disease postoperatively.

Replacement of the Cervical and Thoracic Esophagus in Dog Using Free Jejunal Autografts

Free revascularized jejunal grafts based on a single branch of the mesenteric artery and vein were selected and used for replacement of the cervical esophagus in 20 dogs. The graft pedicle was transplanted to the left external jugular vein and the internal carotid artery using end-to-side microvascular anastomoses. The procedure was successful in all the dogs; however, five dogs had fistula formation that healed spontaneously. A similar jejunal autograft was used to replace the thoracic esophagus in 20 dogs. The recipient vessels were the internal thoracic artery and vein. Only four dogs survived. Thirteen dogs could not survive because of infection resulting from leakage of esophageal content from the esophagojejunal anastomoses into the thoracic cavity. Only two dogs had infarcted jejunal grafts. The four surviving dogs could swallow liquid and semisolid food but they never returned to solid food because of difficulties with swallowing. Graft survival was confirmed with endoscopy and arterial angiography. Narrowed jejunal graft lumen was apparent with contrast radiography and endoscopy. The jejunal grafts kept peristalsis and contracted in coordinated fashion with the proximal esophagus. At necropsy, wound healing was evaluated using bursting strength and bursting circular wall tension. Although slight adhesion and fibrosis around the grafts as well as slight inflammatory reaction around the suture material were observed, the jejunal grafts were grossly and microscopically normal. All esophagojejunal anastomoses healed and the jejunal mucosa looked normal.