Perry L. Habecker

Efficacy of commercial and field-strain Mycobacterium paratuberculosis vaccinations with recombinant IL-12 in a bovine experimental infection model

The efficacy of commercial (Strain 18) and field-isolate paratuberculosis vaccine preparations was investigated. The effect of prior exposure to Mycobacterium paratuberculosis and the adjuvant effect of rIL-12 on vaccine efficacy were also tested. Both Strain 18 and field-isolate vaccines induced strong local, systemic and enteric IFN-gamma responses. A significant reduction in mycobacterial colonization was observed when calves were vaccinated with the field-isolate prior to challenge, but not following vaccination with Strain 18 vaccine. Vaccination with rIL-12 prevented infection in some calves but its overall effect on IFN-gamma response and total mycobacterial load was not statistically significant. Efficacy of paratuberculosis vaccines may be enhanced if calves are vaccinated prior to M. paratuberculosis exposure with field-isolate vaccine instead of Strain 18 vaccine currently in use.

In vivo evaluation of a new bioabsorbable self-expanding biliary stent.

BACKGROUND Bioabsorbable stents may offer advantages for the treatment of benign and malignant biliary strictures, including large stent diameter, decreased biofilm accumulation and proliferative changes, elimination of the need for stent removal and imaging artifacts, and prospects for drug impregnation. However, suboptimal expansion has hampered prior iterations. A new bioabsorbable biliary stent (BioStent) was evaluated in a porcine model. METHODS BioStents were placed in 8 animals for long-term follow-up. The following were evaluated: accuracy and ease of delivery and deployment, radial expansion, and radiologic visualization. Stent function and biotolerance were assessed by cholangiography, serum bilirubin, and necropsy for histopathology performed in pairs at 2, 4, 6, and 12 months. RESULTS Stents were delivered without sphincterotomy and were deployed easily, accurately, and with good immediate stent expansion and radiographic visualization. On follow-up, all stents were fully expanded and serum bilirubin levels remained within the normal range. Although there was no clinical evidence of biliary obstruction, filling defects were common at cholangiography. On histopathologic evaluation, there was neither bile duct integration or proliferative change. CONCLUSIONS The BioStent bioabsorbable biliary stent, modified with axial runners, can be effectively deployed endoscopically, is self-expanding, is visualized radiographically, and remains patent up to 6 months. There was no bile duct integration or proliferative change, which are potential advantages. Stent occlusion and migration remain concerns.

Incidence of Polysaccharide Storage Myopathy in Draft Horse-Related Breeds: A Necropsy Study of 37 Horses and a Mule

Skeletal muscle samples from 38 draft horse–related animals 1–23 years of age were evaluated for evidence of aggregates of glycogen and complex polysaccharide characteristic of equine polysaccharide storage myopathy (EPSSM). Cardiac muscle from 12 of these horses was also examined. Antemortem serum levels of creatine kinase (CK) and aspartate aminotransferase (AST) from 9 horses with EPSSM and 5 horses without EPSSM were compared. Skeletal muscle from 17 horses contained inclusions of periodic acid–Schiff (PAS)-positive, amylase-resistant complex polysaccharide. Similar inclusions were also present in the cardiac muscle of 1 horse. A vacuolar myopathy with aggregates of PAS-positive, amylase-sensitive glycogen was seen in 8 other horses, and these findings are also considered diagnostic for EPSSM. Antemortem serum activities of CK and AST were often higher in EPSSM horses than in horses without EPSSM. Using the presence of amylase-resistant complex polysaccharide as the criterion for diagnosis of EPSSM, the incidence in this population was 45%. Inclusion of horses with aggregates of glycogen but no amylase-resistant complex polysaccharide as representative of the range of pathologic findings in horses with EPSSM resulted in a 66% incidence in this population.

Stent Placement of Gastroenteric Anastomoses Formed by Magnetic Compression

PURPOSE To evaluate the use of stents for prolonging the patency of gastroenteric anastomoses (GEA) induced by magnet compression. MATERIALS AND METHODS Rare earth magnets were inserted perorally and serially in 15 dogs so as to mate across the gastric and jejunal walls. After magnet excretion, the resulting GEA was identified endoscopically, dilated (n = 1), and stented with bare (n = 2) or partially covered (n = 6) flared 10-mm or 12-mm Z stents. The GEA was followed at 2-4-week intervals for patency; malfunctioning shunts were irrigated, or dilated with angioplasty balloons. Gross and histologic examination of the anastomotic tissues was performed in 14 animals. RESULTS Magnet pairs were excreted in 5-7 days. Of the 19 magnet placements in 15 animals, stent placement was not possible because of early GEA closure (n = 6), failure to locate (n = 2), pancreatic abscess (n = 1), and magnet perforation with peritonitis (n = 1). Estimated duration of GEA patency was 19 days after balloon dilation, 40-64 days with bare Z stents, and 58-147 days (mean, 90 days) with partially covered Z stents. Shunt function was commonly hindered by bezoars. Stent narrowing or occlusion was caused by tissue overgrowth through bare stents (n = 2), between covered stent struts and through partially detached membrane (n = 2). Serious morbidity (n = 2) was due to malpositioned magnets across the pancreas in one animal and gastric perforation in the other. One dog was euthanized because of unsuspected kidney infection. CONCLUSION Partially covered stents significantly extend the anatomic patency rate of magnetic GEA to 7 weeks or more. Functional patency is frequently impaired by bezoars. Ongoing improvements in covered stent design should provide longer-term GEA patency.

Effect of subcutaneous administration of a killed Mycobacterium avium subsp paratuberculosis vaccine on colonization of tissues following oral exposure to the organism in calves

OBJECTIVE-To evaluate the effect of vaccination of calves with a killed Mycobacterium avium subsp paratuberculosis (MAP) vaccine on colonization of tissues following oral MAP exposure. ANIMALS-12 healthy Holstein calves. PROCEDURES-At 14 days after birth, calves received the MAP vaccine (1.0 mL, SC) or saline (0.9% NaCl) solution (1.0 mL, SC [control treatment]). Each calf received 1.2 x 10(9) CFUs of live MAP orally 21 and 22 days after vaccination. Prior to vaccination and at subsequent intervals, a blood sample was collected for ELISA detection of antibodies against MAP and for whole blood, antigen-specific, interferon (IFN)-gamma-release assay. Nine weeks after MAP challenge, calves were euthanized and various tissue samples were collected for mycobacterial culture. Interferon-gamma production in prescapular lymph node cells was measured following in vitro stimulation with MAP antigens. RESULTS-Calves were seronegative for anti-MAP antibodies at all times. Compared with the findings in control calves, antigen-specific IFN-gamma production in circulating lymphocytes and prescapular lymph node cells from vaccinated calves was significantly higher. Culture of tissues from vaccinated calves yielded significantly fewer CFUs of MAP (2,417 CFUs/g), compared with tissues from control calves (15,709 CFUs/g). Furthermore, significantly fewer tissue samples from vaccinated calves yielded MAP in culture (21.8 tissues/calf), compared with findings in control calves (27.6 tissues/calf). CONCLUSIONS AND CLINICAL RELEVANCE-Inoculation of calves with a killed MAP vaccine was associated with reduced colonization of intestinal tissues following experimental exposure to MAP. Use of the vaccine could potentially reduce transmission of MAP to calves in infected herds.

A Modified Laryngoplasty Approach Promoting Ankylosis of the Cricoarytenoid Joint

Objective: To perform a modification to the standard laryngoplasty procedure in vivo that would result in ankylosis of the cricoarytenoid (CA) joint, and determine the stability provided to the abducted arytenoid in vitro. Study Design: Experimental study. Animals: Horses (n=8). Methods: Horses were assigned to either control laryngoplasty (n=3) or modified laryngoplasty (5) procedure. Endoscopic upper airway evaluations were used to measure right:left quotients 1 day and 3 months postoperatively to assess maintenance of abduction. Horses were euthanatized 3 months after surgery and larynges collected for measurement of translaryngeal impedance and histologic evaluation of CA joint ankylosis. Each specimen was exposed to increasing negative pressure with the sutures intact or cut while translaryngeal impedance was recorded. Data were analyzed using ANOVA with significance set at P<.05. Results: Loss of left arytenoid cartilage abduction at 3 months was greater in the control laryngoplasty group. Overall, impedance was significantly lower for the modified laryngoplasty group compared with the control laryngoplasty group and lower with the sutures intact than cut. Histologic evaluation of the joints confirmed fibrous bridging of the left CA joints of the modified laryngoplasty group. Conclusions: A modified laryngoplasty approach promotes ankylosis of the CA joint and decreases the loss of abduction of the arytenoid.OBJECTIVE To perform a modification to the standard laryngoplasty procedure in vivo that would result in ankylosis of the cricoarytenoid (CA) joint, and determine the stability provided to the abducted arytenoid in vitro. STUDY DESIGN Experimental study. ANIMALS Horses (n=8). METHODS Horses were assigned to either control laryngoplasty (n=3) or modified laryngoplasty (5) procedure. Endoscopic upper airway evaluations were used to measure right:left quotients 1 day and 3 months postoperatively to assess maintenance of abduction. Horses were euthanatized 3 months after surgery and larynges collected for measurement of translaryngeal impedance and histologic evaluation of CA joint ankylosis. Each specimen was exposed to increasing negative pressure with the sutures intact or cut while translaryngeal impedance was recorded. Data were analyzed using ANOVA with significance set at P<.05. RESULTS Loss of left arytenoid cartilage abduction at 3 months was greater in the control laryngoplasty group. Overall, impedance was significantly lower for the modified laryngoplasty group compared with the control laryngoplasty group and lower with the sutures intact than cut. Histologic evaluation of the joints confirmed fibrous bridging of the left CA joints of the modified laryngoplasty group. CONCLUSIONS A modified laryngoplasty approach promotes ankylosis of the CA joint and decreases the loss of abduction of the arytenoid.

Zinc Phosphide Intoxication of Wild Turkeys (Meleagris gallopavo)

Zinc phosphide (Zn3P2) is a rodenticide used to control a variety of small mammal species. It is available over-the-counter or as a restricted-use pesticide depending on how it is to be applied. The toxicity of Zn3P2 is dependent on the species exposed, whether the animal is able to vomit or not, and whether it is ingested on a full or empty stomach. Nontarget species can be exposed through inadvertent or intentional product misapplication. In this article we describe four mortality events in which wild turkeys (Meleagris gallopavo) were believed to have been intoxicated following the ingestion of baits containing Zn3P2.

Acquired jejunal pseudodiverticula in a yearling Arabian filly.

OBJECTIVE To report a case of multiple acquired jejunal pseudodiverticula managed successfully by resection and jejunojejunostomy. STUDY DESIGN Clinical report. ANIMALS Arabian filly. METHODS The filly was referred for signs of acute colic of several hours duration and had a 2-week history of inappetence and weight loss. Three meters of thickened, edematous, and dilated jejunum removed during exploratory celiotomy had an intussusception and numerous diverticula; jejunojejunostomy performed. The pathoanatomic diagnosis was proliferative enteropathy with pseudodiverticula formation and jejunal muscular hypertrophy and diverticulosis. The diverticula appeared to be acquired; however, the exact cause was not determined. RESULTS There were no postoperative gastrointestinal complications and 1 year later, the filly was doing well. CONCLUSION Multiple acquired jejunal pseudodiverticula not associated with classic muscular hypertrophy can occur in young horses. Long-term prognosis seemingly can be excellent after resection and jejunojejunostomy. CLINICAL RELEVANCE Compared with other reports of small intestinal diverticula in horses, this case is unique because it was not congenital or associated with classic muscular hypertrophy.

Idiopathic disseminated intracytoplasmic neuronal vacuolation in a neonatal Holstein calf born in the USA

Histopathologic, immunohistochemical, and ultrastructural evaluations were made of a 6-day-old Holstein calf with severe vacuolation of the neuronal perikarya that was widely distributed throughout the central nervous system. No evidence of storage material within the vacuoles was revealed by histopathologic and ultrastructural examinations. Immunohistochemical and electron microscopic examinations were negative for protease-resistant prion protein and scrapie-associated fibrils, respectively. These results indicate that the clinical signs in this calf were not associated with transmissible spongiform encephalopathy. Neuronal vacuo-lation has not previously been documented in calves.

Hepatocellular carcinomas in Vietnamese pot-bellied pigs (Sus scrofa):

Various neoplasms have been reported in Vietnamese pot-bellied pigs (Sus scrofa) with few reports of hepatocellular tumors. Twenty-two pot-bellied pigs diagnosed with hepatocellular carcinoma at necropsy over a 3-year period at one institution are described, representing 29% of the total pot-bellied pigs necropsied. The average age of affected pigs was 16.6 years with 15 males and 7 females. The most common clinical signs were decreased appetite (16/22) and weight loss (7/22). Grossly, the majority were massive tumors (13/22) with fewer nodular tumors (8/22) and 1 diffuse tumor. Massive tumors were typically multilobulated, very large, and encompassing 1 or more adjacent liver lobes, and were soft to firm and tan-yellow to orange-brown. Nodular tumors had multiple, 1–15 cm in diameter, discrete nodules in multiple liver lobes. Gross evidence of abscesses, necrosis, hemorrhage, or cysts associated with the tumor was occasionally described. Half of the cases had possible intrahepatic metastasis, and extrahepatic metastasis was identified in 3 cases, including to the hepatic lymph node (1/3), lung (2/3), spleen (1/3), and kidney (1/3). Histologically, all tumors had a trabecular or solid pattern, or a combination. An adenoid pattern was only identified in small regions of a few tumors. The neoplastic cells were relatively well-differentiated with moderate pleomorphism and a low mitotic index. Other histologic features within the tumors included intracellular glycogen or lipid accumulation, extramedullary hematopoiesis, foci of coagulative necrosis, and bile stasis. Aged pot-bellied pigs can be predisposed to hepatocellular carcinomas, which are locally aggressive and can metastasize within the liver and to other organs.