Effect of prior serial in vivo passage on the frequency of Salmonella enteritidis contamination in eggs from experimentally infected laying hens

Experimental infection models are valuable tools for understanding and preventing the deposition of Salmonella enteritidis inside eggs. Oral inoculation is believed to closely simulate naturally occurring S. enteritidis infections of chickens, but oral infection studies have often generated relatively low frequencies of egg contamination. The present study assessed whether repeated in vivo passage of an S. enteritidis strain could affect its ability to cause egg contamination in experimentally infected hens. The incidence of egg contamination was determined in groups of hens inoculated orally with either a phage type 13a S. enteritidis strain or derivatives of this parent strain that were obtained by three successive rounds of passage and reisolation from tissues of infected hens. Passaged S. enteritidis isolates recovered from ovaries and oviducts induced a significantly higher incidence of egg contamination (16.97%) than was attributed to the parent strain (8.27%). However, passaged S. enteritidis isolates recovered from livers and spleens were not associated with a significantly increased frequency of deposition in eggs. By either inducing or selecting for the expression of relevant microbial properties, passage of S. enteritidis through reproductive tissues of chickens may be useful for improving the efficiency at which experimental infection models produce egg contamination.     

Strategies to reduce feedlot cattle heat stress: effects on tympanic temperature

Three experiments were conducted to evaluate the effect of different management strategies on body temperature of feedlot steers finished in the summer months. In Exp. 1, 24 crossbred steers were chosen to assess the effect of altered feed intake and feeding time on tympanic temperature (TT) response. Managed feeding (MF) treatments were applied for 22 d only and provided 1) ad libitum access to feed at 0800 (ADLIB), 2) feed at 1600 with amount adjusted so that no feed was available at 0800 (BKMGT), 3) feed at 1600 at 85% of predicted ad libitum levels (LIMFD). During heat stress conditions on d 20 to 22 of MF, LIMFD and BKMGT had lower (P < 0.05) TT than ADLIB from 2100 through 2400. A carryover effect of limit-feeding was evident during a severe heat episode (d 36 to 38) with LIMFD steers having lower (P < 0.05) TT than ADLIB. In Exp. 2, TT were obtained from 24 crossbred steers assigned to three treatments, consisting of no water application (CON), water applied to feedlot mound surfaces from 1000 to 1200 (AM) or 1400 to 1600 (PM). From 2200 to 0900 and 1200 to 1400, steers assigned to morning sprinkling treatment had lower (P < 0.05) TT than steers assigned to afternoon sprinkling treatment. In Exp. 3, 24 steers were utilized in a 2 x 2 factorial arrangement of treatments with factors of feeding time [0800 (AMF) and 1400 (PMF)] and sprinkling (WET and DRY). Tympanic temperatures were monitored under hot environmental conditions on d 30 to 32 and 61 to 62. A feeding time x sprinkling interaction (P < 0.001) was evident on d 30 to 32, although AMF/DRY steers had the highest (P < 0.05) TT. On d 61 to 62, TT of PMF steers was higher (P < 0.05) than AMF between 1500 to 1800. Use of sprinklers can effectively reduce TT of feedlot cattle, whereas shifting to an afternoon vs morning feeding time was most beneficial when bunks were empty several hours prior to feeding.     

Carbon dioxide laser resection of a distal carpal pilomatricoma and wound closure using swine intestinal submucosa in a dog

A carbon dioxide laser was used to incise around, dissect, and remove a 2-cm intradermal mass from the left carpus of an 8-year-old, spayed female wheaten terrier. The wound was partially closed, resulting in a 3-cm diameter circular defect with extensor tendons exposed. A swine intestinal submucosa graft was utilized to cover the remaining defect. The graft was removed 5 days later, revealing a healthy granulation tissue bed covering previously exposed tendons with minimal wound margin retraction. The remaining wound was allowed to heal by contraction and epithelialization that was complete by 5 weeks postoperatively. The mass, a pilomatricoma, had not recurred at the last follow-up contact 18 months after surgery. Pilomatricoma, laser application, swine intestinal submucosa grafting, and postoperative wound management are discussed.     

Cerebrospinal fluid glutamine,tryptophan, and tryptophan metabolite concentrations in dogs with portosystemic shunts

OBJECTIVE: To determine whether glutamine (GLN), tryptophan (TRP), and tryptophan metabolite concentrations are higher in cerebralspinal fluid (CSF) dogs with naturally occurring portosystemic shunts (PSS), compared with control dogs. ANIMALS: 11 dogs with confirmed PSS and 12 control dogs fed low- and high-protein diets. PROCEDURE: Cerebrospinal fluid and blood samples were collected from all dogs. Serum and CSF concentrations of GLN, alanine, serine, TRP, 5-hydroxyindoleacetic acid (5-HIAA), and quinolinic acid (QUIN) were measured. RESULTS: Cerebrospinal fluid concentrations of GLN, TRP, and 5-HIAA were significantly higher in PSS dogs, compared with control dogs fed high- or low-protein diets. Cerebrospinal fluid QUIN concentration was significantly higher in PSS dogs, compared with control dogs fed the low-protein diet. Serum QUIN concentration was significantly lower in PSS dogs, compared with control dogs fed either high- or low-protein diets. CONCLUSIONS AND CLINICAL RELEVANCE: An increase in CNS GLN concentration is associated with high CSF concentrations of TRP and TRP metabolites in dogs with PSS. High CSF 5-HIAA concentrations indicate an increased flux of TRP through the CNS serotonin metabolic pathway, whereas high CSF QUIN concentrations indicate an increased metabolism of TRP through the indolamine-2,3-dioxygenase pathway. The high CSF QUIN concentrations in the face of low serum QUIN concentrations in dogs with PSS indicates that QUIN production from TRP is occurring in the CNS. High concentrations of QUIN and other TRP metabolites in the CNS may contribute to neurologic abnormalities found in dogs with PSS and hepatic encephalopathy.     

Pathogenesis and outcome of extrahepatic biliary obstruction in cats

Extrahepatic biliary obstruction (EHBO) was confirmed at surgery or necropsy in 22 cats. Biliary or pancreatic adenocarcinoma was diagnosed by histopathology in six cats and one cat had an undiagnosed mass in the common bile duct. The remaining 15 cats had at least one of a complex of inflammatory diseases including pancreatitis, cholangiohepatitis, cholelithiasis and cholecystitis. The most common clinical signs were jaundice, anorexia, lethargy, weight loss and vomiting. Hyperbilirubinaemia was present in all cases. Distension of the common bile duct and gall bladder was the most commonly observed finding on abdominal ultrasound. Nineteen cats underwent exploratory laparotomy for biliary decompression and diversion. Mortality in cats with underlying neoplasia was 100 per cent and, in those with non-neoplastic lesions, was 40 per cent. Long-term complications, in those that survived, included recurrence of cholangiohepatitis, chronic weight loss and recurrence of obstruction. Based on these findings, the prognosis for EHBO in cats must be considered guarded.     

Cardiopulmonary bypass in the cat

OBJECTIVE: To assess the physiologic response to, and acute survival of, cats undergoing cardiopulmonary bypass (CPB) and to evaluate the efficacy of a commercial human pediatric oxygenator system on cats weighing less than 6 kg. STUDY DESIGN: Experimental study. ANIMALS: Six intact male cats METHODS: Cats were placed on cardiopulmonary bypass by cannulating the cranial and caudal vena cavae and the carotid artery. The pediatric CPB circuit was primed with 150 mL of a balanced crystalloid solution. Venous drainage was enhanced by a controlled, vacuum-assist system. A cross-clamp was placed on the ascending aorta and cardiac arrest was induced by antegrade infusion of a cold cardioplegia solution. After 45 minutes of arrest time, the cross-clamp was removed and the cats were weaned off bypass and decannulated. No blood products were administered. Heart rate, mean arterial pressure (MAP), central venous pressure, arterial blood gas, hematocrit (HCT), total plasma protein concentration (TP), serum electrolyte concentrations, and activated clotting time (ACT) were measured at baseline period (BL), during CPB, 60 minutes after CPB (CPB 60) and 90 minutes after CPB (CPB 90). A complete blood count (CBC), blood chemistry profile, and urinalysis were performed at BL, during CPB, and CPB 90. Cats were euthanatized after CPB 90. RESULTS: Cardiopulmonary bypass resulted in a significant (P <.05) decrease in mean HCT (18.0%) and TP (2.3 gm/dL) at CPB 90 when compared to BL (30.5% and 6.0 gm/dL, respectively). The MAP at CPB 90 (54 mm Hg) was decreased from BL (94 mm Hg). The ACT increased from a mean of 124 seconds to > 400 seconds with heparinization and was reversed to 300 seconds with protamine. Mean platelet counts decreased from BL (369,000 /microL) to CPB 90 (94,500 /microL). Mean white blood cell counts decreased from 13,200 /microL at BL to 2,200 /microL at CPB 90. Upon reperfusion, 1 cat fibrillated but was successfully defibrillated. CONCLUSIONS: Cardiopulmonary bypass was performed successfully in 6 cats weighing less than 6 kg. Acute survival to 90 minutes after CPB was achieved in all 6 cats CLINICAL RELEVANCE: The ability to perform CPB in the cat may allow intracardiac repair of various heart defects in this species.     

Altered expression of G proteins in thyroid gland adenomas obtained from hyperthyroid cats

OBJECTIVE: To determine whether expression of G proteins (G(i) and G(s)) is altered in thyroid gland adenomas obtained from hyperthyroid cats. SAMPLE POPULATION: Adenomatous thyroid glands obtained from 8 hyperthyroid cats and thyroid glands obtained from 4 age-matched euthyroid cats. PROCEDURE: Expression of G(i) and G(s) was quantified in enriched membrane preparations of thyroid gland tissue, using immunoblotting with G(i) and G(s) antibodies and toxin-catalyzed ADP-ribosylation. RESULTS: Expression of G(i) was significantly reduced in thyroid gland adenomas from hyperthyroid cats, compared with normal thyroid gland tissue from euthyroid cats. Expression of G(s) was similar between the 2 groups. CONCLUSIONS AND CLINICAL RELEVANCE: A decrease in expression of G in adenomatous thyroid glands of cats may reduce the negative inhibition of the cAMP cascade in thyroid cells, leading to autonomous growth and hypersecretion of thyroxine. Understanding the molecular mechanisms for hyperthyroidism in cats may lead to better treatment or, ultimately, prevention of the disease.