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4 scientific articles to use in everyday practice

Summaries of subjective classic papers

Chest tube in a 5-year-old pointer.
Photos by Phil Zeltzman, DVM

What would you consider to be the definition of a classic scientific article? In my mind, it is an article that changes the way you think. It is an article that changes the status quo. That changes the way you practice—the very next day. The following are four summaries of classic papers, chosen from a list that is necessarily subjective.

How much fluid does a chest tube generate?

When is it appropriate to remove a thoracostomy tube? The tube is generally removed when it only produces the amount of fluid that a tube spontaneously generates in a normal dog.

For decades, veterinarians have repeated the same mantra: A tube normally generates 2 ml of fluid/kg/day in a normal dog.

However, the problem is, to the best of our knowledge, no study has ever been published in veterinary medicine. The mantra was extrapolated from human medicine.

Until, Germaine Hung, DVM, MVetSc, DACVS-SA, VCA Canada, and her colleagues performed the study everybody had been waiting for.1

Thoracostomy tubes were placed in eight healthy coonhound-mix dogs. Two methods were used to measure the volume of pleural effusion: using computed tomography (CT) images and direct aspiration of fluid via the tube over seven days.

The mean volume of pleural fluid aspirated was 0.48 ml/kg/day, whereas the amount calculated based on CT images was 1.43 ml/kg/day. Conclusion: The amount assessed by either technique was significantly less than the expected volume of 2 ml/kg/day.

Incidentally, the authors cultured the fluid and grew Staphylococcus pseudintermedius and/or Streptococcus equi subspecies zooepidemicus.

This is a great reminder of another mantra: A thoracostomy tube, like any drain, is a two-way street. This means it can introduce bacteria into the patient in an ascending manner.

Conclusion: Using aseptic technique during placement and management of the tube is truly imperative. Chest tubes produce an average of 1 ml/kg/day of fluid.

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Is it the hip or the knee?

Michelle Powers, DVM, DACVS, showed in a classic article that one-third of dogs referred to a surgeon for hip dysplasia have in fact a torn ACL.2

Almost half of the dogs that were in the study were Labrador retrievers, German shepherds, and golden retrievers.

Radiographs did indeed show hip dysplasia in 94 percent of these dogs, but pain in one-third of patients was in the knee.

It is important to rule out other sources of stifle joint disease before making recommendations for treatment of hip dysplasia. Clinical signs may be absent in at least three-fourths of dogs with radiographic evidence of the hip dysplasia.

With hind-leg lameness, perform a thorough orthopedic exam of all joints, and radiograph both the hips and the knees. Remember, as the saying goes, “We don’t treat X-rays; we treat dogs.”

Conclusion: Assume that a dog with hind limb lameness has a stifle issue until proven otherwise.

Should the abdomen stay open to drain?

Treatment for generalized septic peritonitis historically often included open abdominal drainage (OAD). This procedure is becoming less common because of the intense management, the need for frequent sterile bandage changes, the high morbidity, and the costs involved.

The purpose of this classic article, written by Otto Lanz, DVM, DACVS, is to evaluate surgical outcomes of dogs treated surgically without postop OAD.3

In most cases (75 percent), septic peritonitis was due to leakage from the gastrointestinal tract.

Treatment included correction of fluid and electrolyte abnormalities, appropriate antimicrobial therapy, and exploratory laparotomy. Surgical correction of the problem was followed by aggressive peritoneal lavage, appropriate postop antibiotics, plasma transfusions, etc. In other words, OAD was not performed.

The mortality rate of dogs in this study was 46 percent, which is comparable to previous studies in which the abdomen was left open postop. This suggests that OAD may not be necessary as long as the cause has been eliminated surgically and aggressive supportive care is provided.

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The following sequence of events can therefore be recommended:

  1. Remove the identified source of contamination.
  2. Lavage with copious amounts of warm, sterile fluids.
  3. Avoid OAD at all costs.
  4. Base antibiotic choices on cultures obtained.
  5. Be prepared to provide intensive supportive care postop—or refer to someone who will.

Conclusion: Avoid OAD at all costs.

Intestine: Is a continuous pattern safe?

Intestinal lymphoma in a 12-year-old Jack Russell terrier.

Debra Weisman, DVM, DACVS, and her colleagues authored a now-classic study in which showed that a simple continuous suture pattern helps decrease mucosal eversion and provides more accurate apposition of the tissue layers when suturing the small intestine after a resection and anastomosis (R&A).

Additional benefits include a quicker closure, shorter anesthesia time, and significantly less foreign material (i.e. sutures) placed in the patient. In order to avoid a purse-string effect if the suture is too tight, two separate sutures are used rather than one.

One knot is preplaced at the mesenteric border and one at the anti-mesenteric border. A 3-to-4-centimeter-long strand of suture material (polydioxanone) is tagged with a hemostat and used as a stay suture. The continuous suture is started on the mesenteric side, along one side of the intestine, up to the knot on the anti-mesenteric side. The intestine is flipped over.

The second continuous suture is now placed on the opposite side of the intestine, down to the mesenteric side. Tissue bites are full thickness. They are placed about 3 mm apart and 3 mm from the edge of the intestine. Each suture line is then tied to the short stay sutures.

This concept was put to the test on R&A patients, which were followed for an average of more than two years. The results were considered excellent.

Conclusion: Use a continuous suture for an R&A.

References

  1. Hung GC, et al. Quantification and characterization of pleural fluid in healthy dogs with thoracostomy tubes. AJVR. 2016; 77(12): 1387-1391.
  2. Powers MY, et al. Prevalence of cranial cruciate ligament rupture in a population of dogs with lameness previously attributed to hip dysplasia: 369 cases (1994–2003). J Am Vet Med Assoc. 2005; 227(7): 1109-1111.
  3. Lanz O, et al. Surgical treatment of septic peritonitis without abdominal drainage in 28 dogs. JAAHA. 2001; 37(1): 87-92.
  4. Weisman DL, et al. Comparison of a continuous suture pattern with a simple interrupted pattern for enteric closure in dogs and cats: 83 cases (1991-1997). J Am Vet Med Assoc. 1999; 214(10): 1507-1510.
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Dr. Phil Zeltzman is a board-certified veterinary surgeon and author. His traveling surgery practice takes him all over Eastern Pennsylvania and Western New Jersey. Visit his websites at DrPhilZeltzman.com and VeterinariansInParadise.com.

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