Wound contamination and antimicrobial susceptibility of bacteria cultured during total ear canal ablation and lateral bulla osteotomy in dogs.

OBJECTIVE: To detect contamination of wound sites from surgical handling of excised tissues during total ear canal ablation and lateral bulla osteotomy in dogs, and to compare susceptibility of bacterial isolates to cefazolin with susceptibility to other antimicrobial agents. DESIGN: Prospective clinical study. ANIMALS: 13 dogs. PROCEDURE: Dogs were treated surgically for otitis externa and media via total ear canal ablation and lateral bulla osteotomy. Specimens for aerobic bacterial culture were obtained from SC tissue immediately following skin incision, tissues excised from the osseous bulla (after transection of the horizontal ear canal and lateral bulla osteotomy), and from SC tissue prior to skin closure. Antimicrobial susceptibility of bacterial isolates to various antibiotics was determined by use of a broth dilution assay. RESULTS: There was a significant association between isolation of Streptococcus canis and Escherichia coli from specimens from the osseous bulla and specimens from the SC tissues prior to skin closure, indicating contamination of the SC tissues during surgery. Seventy percent of bacterial isolates were susceptible to cefazolin. CLINICAL IMPLICATIONS: Measures to limit bacterial contamination resulting from tissue handling during total ear canal ablation and lateral bulla osteotomy are necessary. Bacteriologic culture of tissue of the osseous bulla and determination of antimicrobial susceptibility are recommended. Administration of cefazolin alone may not be efficacious for antimicrobial prophylaxis.     

COMPARISON OF TRANSCOLONIC 123I-IODOAMPHETAMINE AND PORTAL VEIN INJECTION OF 99mTc-MACROAGGREGATED ALBUMIN SHUNT FRACTION CALCU-LATIONS IN EXPERIMENTAL DOGS WITH ACQUIRED POR-TOSYSTEMIC SHUNTS

Shunt fraction was determined using transcolonic ¹²³I-iodoamphetamine (IMP) and portal vein injection of ^99mTc-macroaggregated albumin (MAA) in a group of eight dogs with chronic cirrhosis and acquired portosystemic shunts subsequent to total common bile duct ligation. Hepatic parenchymal damage was confirmed by alterations in liver function tests and liver histology. Seven of the eight dogs developed portal hypertension and had angiographic evidence of hepatofugal portal blood flow with multiple peripheral portosystemic anastomoses. Shunt fractions determined in the seven dogs with shunts varied from 39 to 100 using IMP and 45 to 93 using MAA. The remaining dog had normal portal pressure, a normal portal angiogram, and normal IMP and MAA scintigraphic studies. There was an excellent correlation between the two methods of shunt fraction calculation (R²= 0.98) and the line of regression was not significantly different from unity (IMP = 1.09 × MAA - 0.03).     

Use of transcolonic 99mtechnetium-pertechnetate as a screening test for portosystemic shunts in dogs

99mTechnetium-pertechnetate, when administered in high concentration into the colon, is rapidly absorbed across the colonic mucosa and results in a nuclear angiogram of the portal circulation. In normal dogs, a series of dynamic lateral scintigraphic images of the abdomen resulted in sequential visualization of the portal vein, liver, and several seconds later, the heart and lungs. In contrast, studies performed in 9 dogs with surgically confirmed portosystemic shunts demonstrated a different pattern of distribution, with heart and lung activity occurring before liver activity. In several cases, the aberrant shunt vessels could be identified. Studies were easy to perform, were well tolerated, and required no computer processing for interpretation.     

Influence Of Allopurinol On The Pathophysiology Of Experimental Gastric Dilatation-Volvulus

Gastric dilatation-volvulus (GDV) was surgiclly induced in 10 dogs. Five of the dogs were pretreated with 50 mg/kg PO of allopurinol to determine the effect of xanthine oxidase inhibition on the pathophysiology of GDV. After 150 minutes, the GDV was corrected, and lactated Ringer's solution was administered intravenoulsy (resuscitation). Two hundred forty minutes after relief fo GDV, the dogs were euthanatized without recovery from anesthesia. Administration of allopurinol was associated with a reduced (P<0.01) incidence of hepatic necrosis and a lower (P<0.045) serum phosphorus level than observed in the control group at the end of the experiment. The increase in base deficit in the allopurinol-treated group after resuscitation was also less(P<0.045) than the control group. In conclusion, this study suggests that inhibition of xanthine oxidase-derived oxygen free radicals protects against hepatic necrosis in dogs with GDV. Resuscitation appears to be a time of profound physiologic stress for dogs with GDV.