Insulinoma in a cat

A 14-year-old domestic shorthair cat was presented with hypoglycaemia and seizures of several weeks duration. Bloodwork revealed hypoglycaemia (1.83 mmol/l; reference range 4.22-8.05 mmol/l) with concurrent normal insulin levels (171 pmol/l; reference range 72-583 pmol/l). An insulinoma was suspected and medical and dietary management were attempted with minimal success. An exploratory laparotomy was performed and a single, well-defined mass was found within the left lobe of the pancreas. The mass was removed and histologically classified as an islet cell carcinoma, consistent with an insulinoma. The cat had an episode of presumed postoperative pancreatitits, but recovered with appropriate treatment. The cat has had no clinical signs of recurrence of greater than 32 months postsurgery. There are only four cases of insulinoma in cats reported in the literature. All prior insulionomas reported were in older cats and were malignant in character, which is similar to the reports in the dog. This case is unique because of the apparent lack of local recurrence and development of metastatic disease, leading to the prolonged survival.

Paraoesophageal hiatal hernia and megaoesophagus in a three-week-old Alaskan malamute

Paraoesophageal hiatal hernia was diagnosed in a three-week-old Alaskan malamute. Reduction of the hernia was followed by an oesophagopexy and a bilateral gastropexy. During the early postoperative period, the puppy continued to have signs that were thought to be related to a concurrent megaoesophagus. At nine months of age the dog had gained weight and was well except for occasional episodes of regurgitation. These episodes responded well to medical therapy, and at the time of writing the dog had not required further treatment.

Umbilico-biliary fistula in a dog

This case report describes a previously unreported congenital malformation, an umbilico-billary fistula, in a dog. A one-year-old male bulldog was diagnosed with umbilico-billary fistula using fistulography. Treatment involving surgical removal of the fistula was straightforward and resulted in clinical resolution of the problem.

Hiatal hernia and diaphragmatic eventration in a leopard (Panthera pardus)

A 1-yr-old male leopard (Panthera pardus) presented for intermittent anorexia, emaciation, and generalized muscle wasting. Plain radiographs, ultrasonography, and esophageal endoscopy led to a diagnosis of diaphragmatic eventration with probable concurrent hiatal hernia. An exploratory laparotomy confirmed both diagnoses, and surgical repair and stabilization were performed. After surgery, the leopard was maintained on small liquid meals for 4 days, with a gradual return to normal diet over 2 wk. By 4 wk after surgery, the leopard was eating well and gaining weight, and it showed no recurrence of clinical signs for 2 yr subsequently, becoming mildly obese.

Microvascular transplantation of a free omental graft to the distal extremity in dogs

OBJECTIVE

To assess the survival of a free omental graft applied to an experimentally created wound on the distal extremity in dogs.

STUDY DESIGN

A free omental graft was evaluated as a primary method of treatment for dogs with distal extremity wounds in an experimental model.

ANIMALS OR SAMPLE POPULATION

Five adult intact female mixed breed dogs weighing 21.8 kg to 25.0 kg.

METHODS

A free omental graft was harvested from the abdomen and transferred to a wound bed overlying the medial aspect of the tibia. A microvascular anastomosis was performed between the graft vessels and vessels at the recipient site. Daily clinical assessment of graft viability was performed. Angiography and 99mTechnetium labeled macroaggregated albumin (99mTc MAA) scintigraphic perfusion scans were performed on either day 4, 5, or 7. Postmortem collection of tissues for histopathologic analysis was performed immediately after imaging. Total operative time and graft ischemia time were evaluated for effects on graft survival.

RESULTS

Two of seven grafts survived to the end of the study, three of seven grafts failed because of ischemia, and two of seven grafts failed because of self-trauma. There was no clinically significant morbidity associated with the abdominal portion of the procedure. Because of the small number of surviving grafts, the effects of operative time and graft ischemia time could not be statistically evaluated.

CONCLUSIONS

Microvascular transplantation of a free omental graft can result in a viable tissue covering of a distal extremity wound, however, the failure rate is unacceptably high.

CLINICAL RELEVANCE

A free omental graft may not have sufficient durability to be an acceptable wound covering by itself. Further studies combining omentum with a skin graft or other tissues may result in a clinically useful technique.

The use of colonic irrigation to control fecal incontinence in dogs with colostomies

OBJECTIVE

To determine if once-daily colonic irrigation results in fecal continence for a 24-hour period in dogs with colostomies and if colonic volume increased in response to the irrigation.

STUDY DESIGN

A prospective controlled experimental study.

ANIMALS

Four intact male and one intact female mixed breed dogs.

MATERIALS

All dogs received left end-on paralumbar colostomies. Four dogs received once-daily colonic irrigation for 8 weeks, whereas the control dog did not. Daily fecal weights were recorded for the length of the study in all dogs. Barium enema studies and volumetric studies were used to determine colonic volumes.

RESULTS

Daily fecal weights were significantly decreased in treatment dogs compared with the control dog. Colonic volume increased in irrigated dogs in response to daily irrigation over the 8 week period of the study.

CONCLUSIONS

Colonic irrigation resulted in significantly decreased fecal production over a 24-hour period. Therefore management of dogs with colostomies would be more practical and cost effective. It did not result in complete fecal continence in this study. Further clinical studies are indicated to determine if longer periods of irrigation would result in complete continence.

Long-term outcome of medical and surgical treatment of hiatal hernias in dogs and cats: 27 cases (1978-1996)

OBJECTIVE

To determine long-term outcome of medical and surgical treatment of hiatal hernia (HH) in dogs and cats.

DESIGN

Retrospective case series.

ANIMALS

22 dogs and 5 cats.

PROCEDURE

Medical records of dogs and cats with HH were reviewed. Outcomes of treatment were obtained from reexamination or owner questionnaires.

RESULTS

The most common breeds affected were English Bulldog and domestic shorthair cat. Mean age of all dogs and cats was 4 years. Hiatal hernia was diagnosed by use of contrast radiography of the esophagus (n = 19), fluoroscopy (7), or esophagoscopy (1). Eight of 15 dogs and cats treated medically for 30 days had complete resolution of signs. Of the 7 in this group that did not respond, 1 died on the 10th day of medical treatment and the remaining 6 were treated surgically. Eight of 10 dogs that underwent hiatal plication, esophagopexy, and gastropexy responded favorably. Four of 7 dogs that underwent fundoplication did well. However, 3 of these dogs did not have clinical signs. Fundoplication was successful in only 1 of 4 dogs with clinical signs.

CLINICAL IMPLICATIONS

Dogs and cats with clinical signs of reflux esophagitis associated with HH should undergo conservative treatment for 30 days. Most will be managed successfully by use of drugs, dietary alterations, or both. Those that do not respond to conservative treatment will likely require surgery. The best prognosis after, surgery appears to be associated with the esopagopexy technique.

Complications associated with the implantation of polypropylene mesh in dogs and cats: a retrospective study of 21 cases (1984-1996)

Complications associated with implantation of polypropylene mesh in dogs and cats were evaluated retrospectively. Immediate postoperative complications were common (in 10 of 20 cases) but predominantly involved seroma formation which resolved with treatment. The only long-term (i.e., six months or more) complication identified was mass recurrence at the site of tumor resection (in seven of 14 cases). Recurrence was affected by resection size. The average number of ribs resected in cases of thoracic wall neoplasia (with and without mass recurrence) was 1.8 and 3.5, respectively. In this study, implantation of polypropylene mesh facilitated the reconstruction of large tissue defects and was not associated with any serious complications.

Short-term hemodynamic evaluation of circumferential mitral annuloplasty for correction of mitral valve regurgitation in dogs

OBJECTIVE

To determine the short-term hemodynamic effects associated with circumferential mitral annuloplasty (CMA) in dogs with mitral regurgitation.

STUDY DESIGN

Prospective experimental study. Animals-Seven healthy adult mongrel dogs.

METHODS

Mitral regurgitation was surgically induced, and annular dilation occurred. Echocardiography and cardiac catheterization were used to determine forward ejection fraction (FEF), regurgitant fraction (RF), pulmonary capillary wedge pressure (PCWP), and annular diameter before and immediately after CMA in five dogs. FEF and RF were also evaluated 7 days after annuloplasty.

RESULTS

Mean annular diameter and PCWP were significantly reduced immediately after CMA. Significant increases in FEF of 19% and 22% were shown immediately and 7 days after CMA. Significant reductions in RF of 19% and 22% were also shown immediately and 7 days after annuloplasty.

CONCLUSIONS

Sustained hemodynamic benefits and a reduction in annular diameter were achieved by CMA in a canine model of mitral regurgitation.

CLINICAL IMPLICATIONS

CMA may be a suitable treatment for heart failure because of mitral regurgitation when early signs of cardiovascular decompensation persist despite appropriate medical management.

Determination of proximal femoral epiphyseal depth for repair of physeal fractures in immature dogs

OBJECTIVE

To determine the depth that implants may be safely placed for repair of proximal femoral physeal fractures.

STUDY DESIGN

Relationships were determined between the depth of the proximal femoral epiphysis (PFE) and the contralateral PFE, and the PFE and pubic bone width.

ANIMALS OR SAMPLE POPULATION

20 immature dog cadavers.

METHODS

Actual PFE depths were determined at the center of the physeal surface and at four other eccentric points. The contralateral intact PFE depth and the width of the cranial aspect of the public bone were measured from radiographs.

RESULTS

Mean ratios of actual central PFE depth to radiographically measured (1) contralateral PFE depth and (2) pubic bone width were 1.04:1, and 1.09:1, and ratios of actual eccentric PFE depths were 0.89:1 and 0.93:1. Body weight was not useful in estimating depth of the PFE.

CONCLUSIONS

For the central epiphysis, pins may safely be placed a distance equal to 75% to 80% of the contralateral intact PFE depth or pubic bone width, measured from a ventrodorsal radiograph, with minimal risk of penetration through the articular surface. Pins placed eccentrically may be safely driven a depth equal to 65% of the radiographically measured contralateral intact PFE depth or pubic bone width.

CLINICAL RELEVANCE

Estimating the safe depth of implant placement into the PFE avoids penetration of the articular surface.

Determination of safe depth of pin penetration for repair of distal femoral physeal fractures in immature dogs: a comparison of normograde and retrograde pin placement

OBJECTIVE

The purpose of this study was to determine the depth that implants may be safely placed into the distal femoral epiphysis (DFE) for the repair of distal femoral physeal fractures.

STUDY DESIGN

The depth of the DFE was related to the radiographic thickness of the patella in this experimental study.

ANIMALS OR SAMPLE POPULATION

Twenty immature canine cadavers.

METHODS

Patella thicknesses were measured from lateral radiographs. Actual DFE depths were determined for pins driven in normograde fashion and for pins driven retrograde from the central depression between the metaphyseal pegs and from the cranial pegs. The association of DFE depth and patella thickness was evaluated using linear regression analysis. Using 95% confidence intervals, rules for estimating the safe depth of implant placement into the DFE were determined.

RESULTS

DFE depth had significant correlation with patella thickness for pins placed in retrograde fashion from the central depression between the metaphyseal pegs (r2 = .83) and from the cranial pegs (r2 = .82) and for pins placed in normograde fashion (r2 = .65).

CONCLUSIONS

Based on 95% confidence intervals, pins placed in retrograde fashion from the central depression between the metaphyseal pegs may be safely driven into the DFE a distance equal to 140% of patella thickness. Pins placed from the cranial metaphyseal pegs may be driven to a depth equal to 80% of patella thickness, and pins placed in normograde fashion may be driven to a depth equal to 30% of patella thickness.

CLINICAL RELEVANCE

Measurement of patella thickness assists the surgeon in determining the approximate depth that pins may be driven into the DFE without penetrating the articular surface of the stifle joint.

Gradual occlusion of extrahepatic portosystemic shunts in dogs and cats using the ameroid constrictor

Gradual occlusion of the splenic vein, using a specialized device (ameroid constrictor), was evaluated experimentally in three normal beagle dogs. Splenoportograms were used to verify that total occlusion of the splenic vein had occurred in all dogs within 4 to 5 weeks after application of the device. The ameroid constrictor (AC) was also evaluated as a method of gradual vascular occlusion in 12 dogs and two cats with single, extrahepatic, portosystemic shunts (PSS). Serum bile acid (SBA) concentrations were measured and portal scintigraphy (PS) was performed on all 14 animals preoperatively and 10, 20, 30, and 60 days postoperatively. Two dogs (14%) died from portal hypertension in the early postoperative period. One dog and one cat developed multiple acquired PSS, confirmed by mesenteric portography 90 days after the operation. Portal scintigraphy confirmed total occlusion of the primary shunt in the other 10 animals. Shunt fractions (SF), as measured by PS on postoperative days 30 and 60, declined significantly from preoperative values. Significant decreases were noted between preoperative and postoperative values for preprandial SBA on postoperative day 60 and for postprandial SBA on postoperative day 30. SBA concentrations did not correlate with SF. Based on this study, gradual vascular occlusion using the AC is recommended as a method for treatment of single, extrahepatic, PSS.

Myoblast gene therapy in canine mucopolysaccharidosis. I: Abrogation by an immune response to alpha-L-iduronidase

Three dogs with deficiency of the lysosomal enzyme alpha-L-iduronidase were treated by gene replacement therapy targeted at muscle. Direct intramuscular injections of plasmid encoding the alpha-L-iduronidase gene cDNA resulted in no detectable enzyme production, but may have resulted in immunologic sensitization to iduronidase protein, which the dogs lack totally. Myoblasts were grown from skeletal muscle biopsies and transduced with a retroviral vector containing the canine gene under control of the muscle creatine kinase enhancer. Several hundred-fold overexpression of enzyme production occurred in cultured cells; however, following reintroduction of the cultured cells into dogs, enzyme production declined rapidly. Concurrent with the falling enzyme levels, there was production of specific immunoglobulin G (IgG) antibody against iduronidase that was further associated with cellular infiltration of the myoblast injection sites. Most inflammatory cells were lymphocytes and plasma cells, suggesting local humoral and cellular immune responses to the enzyme-producing muscle cells. PCR analysis of tissues collected 2-22 weeks after the final treatment showed the persistence of Neo and canine alpha-L-iduronidase sequences in a progressively decreasing percentage of myoblasts. Results from this study in a canine model of mucopolysaccharidosis I underscore the fact that immunologic reactions to cells producing desirable, normal, but foreign, proteins may be as much an impediment to gene therapy as reactions to the viral vectors used to introduce the foreign gene.

Use of a low-profile gastrostomy device for administering nutrients in two dogs

Percutaneous endoscopic gastrostomy (PEG) tubes are an excellent means of providing nutritional support via the enteral route. Most problems with PEG tubes are associated with their maintenance. A low-profile feeding device has been developed for use in human beings to replace standard PEG tubes in situations in which long-term nutritional support is necessary. We adapted a low-profile feeding device for use in 2 dogs. The device offered the advantage of being easier to maintain than standard PEG tubes. It appeared to have been well tolerated. Its low-profile design is likely to result in few problems resulting from an animal chewing on the device or from accidental dislodgment.

Caecal impaction in a dog

A seven-year-old, intact male dobermann with a four-week history of anorexia was diagnosed as having impaction of the caecum with inspissated faeces. Radiographic and histopathological findings revealed impaction of the caecum and a mild subacute locally extensive typhlitis. Typhlectomy was curative and no further problems have been reported.

Use of a pedicled rectus abdominis muscle flap for repair of a failed vesicourethral anastomosis in a dog

A 10-year-old mixed breed dog underwent a prostatectomy for an adenocarcinoma. Within three days the dog had signs of a uroperitoneum. Re-exploration revealed that a portion of the vesicourethral anastomosis had failed. Primary suturing of the tissue along the site of dehiscence following debridement of the devitalised tissue was impossible. A rectus abdominis muscle flap was created and successfully used to repair the site of leakage.

Self-Assembled Metal Colloid Monolayers: An Approach to SERS Substrates

The self-assembly of monodisperse gold and silver colloid particles into monolayers on polymer-coated substrates yields macroscopic surfaces that are highly active for surface-enhanced Raman scattering (SERS). Particles are bound to the substrate through multiple bonds between the colloidal metal and functional groups on the polymer such as cyanide (CN), amine (NH(2)), and thiol (SH). Surface evolution, which can be followed in real time by ultraviolet-visible spectroscopy and SERS, can be controlled to yield high reproducibility on both the nanometer and the centimeter scales. On conducting substrates, colloid monolayers are electrochemically addressable and behave like a collection of closely spaced microelectrodes. These favorable properties and the ease of monolayer construction suggest a widespread use for metal colloid-based substrates.

Percutaneous endoscopic gastrostomy

Over the past 5 to 7 years, the veterinary profession has benefitted from our increased ability to provide nutrition to the small animal patient who cannot or will not eat. The adaptation of the percutaneous endoscopic gastrostomy (PEG) for use in the dog and cat deserves a great deal of credit in advancing the level of care we can now give to the chronically ill or critical care patient. The PEG is a relatively simple technique that has proved to be a very cost-efficient way to maintain the nutritional status of the small animal patient. In the author's experience, owner acceptance of using the PEG in the home environment on a chronic basis has been excellent.

Comparison of effects of cimetidine and omeprazole on mechanically created gastric ulceration and on aspirin-induced gastritis in dogs

A double-blind study was conducted to compare gastric ulcer healing time in nontreated dogs with that in dogs treated with either cimetidine or omeprazole. Single ulcers were created in the gastric antrum by use of a suction biopsy capsule. Each dog was given 25 mg of aspirin/kg of body weight orally for 20 days after ulcer induction. Five control dogs were given aspirin only (no anti-ulcer medication) during the 20-day study. Six dogs were given cimetidine at dosage of 10 mg/kg orally every 8 hours, and 6 dogs were given omeprazole orally at dosage of 2 mumol/kg (0.7 mg/kg) once daily. All dogs were examined endoscopically on days 5, 10, 15, and 20 and were given a score for the size of the mechanically created ulcer and a score for the degree of aspirin-induced gastritis. All dogs were euthanatized on day 21, and gastric lesions were examined histologically. Significant differences were not evident in ulcer healing scores or degree of aspirin-induced gastritis among treated and nontreated dogs on days 5, 10, 15, and 20. However, aspirin-induced gastritis was less severe in dogs of the omeprazole group than in dogs of the cimetidine or control group on each day observations were made. The effect of omeprazole given once daily was comparable with that of cimetidine given every 8 hours in lessening aspirin-induced gastritis.

Captopril provides sustained hemodynamic benefits in dogs with experimentally induced mitral regurgitation

Mitral regurgitation was created surgically in 10 dogs. After measurement of baseline hemodynamic parameters on day 2, treatment with captopril (2 mg/kg orally 3 times daily) was begun in five dogs. Five control dogs received no therapy during the study. The hemodynamic parameters were measured again at weeks 6 and 22. In the treated dogs, the forward ejection fraction (FEF) increased slightly and the total peripheral resistance index (TPRI) decreased. In the controls, the FEF decreased and the TPRI increased. Changes in FEF and TPRI were significantly different between the two groups. The change in FEF correlated significantly with the change in TPRI in both groups. Although the most dramatic changes were observed at week 6, the differences persisted throughout the study. Captopril administration resulted in sustained hemodynamic improvement and may, therefore, delay the onset of congestive heart failure in dogs with mitral regurgitation.

Gastroduodenal ulceration in dogs. Retrospective study of 43 cases and literature review

Forty three dogs with non-neoplastic canine gastric and/or duodenal ulcers were diagnosed at the University of Tennessee Veterinary Teaching Hospital (UTVTH) and reviewed in conjunction with dogs reported in the literature. No age, sex, or breed predilection was found. Most of the 43 UTVTH dogs presented with clinical signs referable to gastrointestinal disease, but evidence of hemorrhage was not always present. Nonregenerative anemia was a common (33/43 dogs) finding. Diagnosis of ulcer disease was made by contrast radiography, with clinical evidence of gastrointestinal hemorrhage, or surgery, endoscopy, or necropsy. Treatment with nonsteroidal, anti-inflammatory drugs (NSAIDs) and hepatic disease were the two most common predisposing factors for ulcer disease. Dogs with liver disease tended to have duodenal ulcers, dogs receiving NSAID treatment tended to have pyloroantral ulcers, and dogs with mastocytosis had ulcers in multiple locations. Three dogs with duodenal ulcers receiving NSAID treatment had an additional predisposing factor. Surgical treatment (with or without medical treatment) had a good outcome when the predisposing factors could be controlled or eliminated. Only 3 of 27 dogs in both the surgical and medically treated groups died from ulcer disease, whereas 6 of 16 dogs in the untreated group died from ulcer disease.

Transcatheter thoracic duct embolization in the dog. An experimental study

Thoracic duct embolization was created by injecting an isobutyl 2-cyanoacrylate/iophendylate (IBCA) mixture through a cannulated mesenteric lymphatic vessel in eight normal dogs. Aqueous contrast lymphangiography was repeated at minute 10 and week 6. Six dogs were euthanatized at week 6 and two dogs at month 6. Embolization with 1.5 to 3.9 ml of the mixture resulted in complete obstruction of the thoracic duct in all eight dogs. Results of lymphangiography in six dogs at week 6 showed a persistent, complete obstruction of the thoracic duct in six dogs and alternate lymphaticovenous anastomoses in four dogs. Histologically, there were a sclerosing granulomatous response surrounding the lymphatic embolus, mild congestive changes in the mesenteric lymph nodes, and mild lacteal dilatation in the jejunum. The procedure was well tolerated with only a few complications. One dog suffered partial thrombosis of the cranial vena cava by the injected material with later dislodgement and embolization of a pulmonary artery branch. Modifications have been made in the injection procedure to avoid this complication. This technique for occlusion of the thoracic duct shows potential for clinical use in the management of canine chylothorax. The obstruction appears to be complete and permanent, and surgical/anesthetic time is decreased greatly from previously described procedures.

Percutaneous endoscopic tube gastrostomy in dogs

Percutaneous endoscopic tube gastrostomy was performed in 10 dogs, using mushroom-tip catheters (16 to 24 F) maintained in place for 5 to 32 days. Dogs were observed daily. Although placement of the catheter was simple and quick, 3 dogs destroyed their catheters. Patency of the catheter was maintained with or without regular flushings with saline solution. Pyrexia (greater than or equal to 39.4 C) developed in 3 dogs, but the rectal temperature returned to base line within 24 hours after catheter removal. After catheter removal, all wounds healed without complication. All dogs were euthanatized. Five were examined radiographically before euthanasia to determine the fate of the mushroom tip after transection of the catheter at skin level between days 5 and 21, and 5 dogs were evaluated at postmortem examination between days 10 and 32. In all dogs, the tip was not present in the gastrointestinal tract by 96 hours after catheter transection. During postmortem examination of the 5 dogs, minimal inflammatory lesions were seen in the gastric tissue. A gastrocutaneous fistula had formed in each dog, resulting in an adhesion between the stomach and peritoneum.

Effects of the Y-U pyloroplasty on gastric emptying and duodenogastric reflux in the dog

A Y-U pyloroplasty was performed on five healthy adult dogs. Gastric emptying half times (t1/2 GE) of a canned food meal were measured by scintigraphy three times before surgery and three times from 6 to 8 weeks after surgery. Fluoroscopic studies of gastric and duodenal motility were made before surgery and 3, 7, and 35 days after surgery. Clinical observations were made daily throughout the study. Gross and histologic evaluations of the gastroesophageal and pyloric regions were performed at the termination of the study. The t1/2 GE was significantly decreased after surgery. By positive contrast fluoroscopy, the vigor of antral contractions was seen to be decreased in three of the five dogs. On days 7 and 35, fluoroscopic findings were comparable to preoperative studies. Duodenogastric reflux was recognized fluoroscopically in three dogs on four different occasions. This may reflect normal reflux patterns in the dog. No gastrointestinal problems were evident after surgery in four dogs. Reflux esophagitis developed in one dog after surgery, which resolved with therapy. Studies of the Y-U pyloroplasty after 2 months indicated that it decreased gastric emptying time of solid food. Results of postmortem examination showed no abnormal gross or histopathologic changes of esophageal, gastric, or proximal duodenal tissues.

Subtotal colectomy for treatment of acquired megacolon in the dog and cat

The case records of 4 cats and 1 dog with megacolon and constipation were reviewed to study the history, clinical signs, pathologic changes, and longterm results of surgical treatment. The 4 cats had idiopathic megacolon. The dog had megacolon secondary to dietary indiscretion. All animals had radiographic evidence of a large colon, which was confirmed by exploratory coeliotomy. Two of the cats and the dog had an intraoperative finding of megacecum as well. Subtotal colectomy was performed in all cases, with the ileocolic valve being removed in 3 of these cases. End-to-side anastomosis was used to restore the integrity of the bowel. All animals were treated successfully with this surgical technique, as judged by clinical response and owner satisfaction. Histologically, there were no consistent lesions to explain the cause of this disease in the cats.

Influence of dietary composition on gastric emptying and motility in dogs: potential involvement in acute gastric dilatation

Gastric dilatation-volvulus is a dramatic and life-threatening disease of large-breed dogs. The cause is unknown, but ingestion of dry cereal-based food is frequently incriminated as a predisposing factor. The purpose of this study was to examine the effect of commercial diets on gastric motility and emptying in the dog. Four large-breed dogs were fed 3 different diets (diet A = canned meat-based; B = cereal-based with 77% added water; and C = dry cereal-based) in a randomized block design. Each experiment was done in triplicate. Motility was assessed, using 5 AgAgCl electrodes and 2 strain gauges sutured along the serosa of the stomach and proximal duodenum. Dogs were fed at the same time each day and the time to change from the fed to the fasted pattern of gastrointestinal motility (changeover) was measured. Gastric emptying was assessed by recording gastric radioactivity. After feeding a meal mixed with 99mTc-labeled resin, the log of activity was plotted against time, and the half-time of gastric emptying (t1/2 GE) was calculated. Mean (+/- SEM) times from feeding to changeover for the 3 diets were: diet A, 9.7 +/- 0.9; B, 10.5 +/- 0.4; and C, 11.0 +/- 0.8 hours. Diet had minimal influence on the half time of gastric emptying (diet A, 2.2 +/- 0.3; B, 2.6 +/- 0.4; and C, 2.9 +/- 0.3 hours; P greater than 0.05). The data indicate that gastric motility and emptying in healthy large-breed dogs were not affected by dietary composition. Because most large dogs are fed cereal-based food for reasons of cost and ease of use, these diets may have been wrongly incriminated as a predisposing factor in gastric dilatation-volvulus.

Fate of autogenous fat implants in the frontal sinuses of cats

Cats (n = 4) were subjected to a bilateral osteotomy overlying the frontal sinuses. The right sinus of each cat served as a control, and the left sinus was filled with autogenous fat harvested from the subcutaneous region of the ventral part of the abdomen. All 4 cats were euthanatized at 200 days. The experiment was designed to determine whether satisfactory obliteration of the left frontal sinus could be accomplished without the benefit of intraoperative magnification. Grossly, obliteration of all 4 sinuses was accomplished in 3 of 4 cats. Light microscopy revealed fluid and/or regrowth of mucous membrane, both considered to be unfavorable sequelae. Although some fat retained viability in the sinus (50% in one cat, 40% in another), most of the obliteration was from mixed fibrous-adipose tissue or bony ingrowth. The clinical significance of this study was not determined, since all 4 cats were free of sinusitis before adipose tissue implantation.

Effect of shock strength on survival and acute cardiac damage induced by open-thorax defibrillation of dogs

The safety of open thorax defibrillation with single damped sine-wave shocks and 6-cm-diameter electrodes was evaluated in healthy anesthetized dogs. Twenty-one dogs were allotted to 6 groups: Group A were nonshocked controls and groups B through F were given single shocks of 4-, 7-, 12-, 19-, or 32-fold, respectively, greater than a defibrillation threshold dose (30 mA/g of heart). Immediate postshock death resulted in group F dogs; group A through E dogs survived and were killed after 2 days. The incidence and severity of cardiac morphologic damage increased with shock strength (mild damage occurred in 1 of 3 dogs in group C and in 3 of 4 dogs in group D and severe damage occurred in 2 of 3 dogs in group E). The cardiac lesions were characterized grossly and microscopically. In dogs that died immediately after shocking, damage was apparent as pale circular zones of edema and myofibrillar degeneration in the ventricular free walls beneath the electrode placement sites on the cardiac surface. In the dogs that survived 2 days, the defibrillator-induced areas of myocardial necrosis and calcification were concentrated in arc or ringlike patterns beneath the periphery of the electrode placement sites. All dogs that were studied 2 days after shocking had mild fibrinous pericarditis. Postshock electrocardiographic changes were not good indicators of cardiac damage because the mild epicardial inflammatory reaction associated with the surgical procedure produced large ST and T wave changes which masked any changes associated with myocardial necrosis induced by the electric shocks. It was concluded that a substantial safety margin exists between the required defibrillation threshold shock dose and the large shocks required to produce marked cardiac damage or death in healthy dogs.