Outcomes of thoracic surgery in dogs and cats

Summary: Records of 146 dogs and 41 cats that underwent thoracic surgery at The University of Sydney Veterinary Teaching Hospital were reviewed for age, sex, breed, disease, operation date, periods of pre- and post-operative hospitalisation, use of surgical drains and outcome. Animals were assigned to 16 disease categories, the most common being patent ductus arteriosus, traumatic diaphragmatic hernia and oesophageal foreign body in dogs and traumatic diaphragmatic hernia in cats. Differences were observed between disease categories in all the criteria examined. There were almost equal numbers of male (72) and female (74) dogs, the median (range) age was 2.0 (0.2 to 14.0) years, the median pre-operative stay was 1 (0 to 14) days, the median post-operative stay was 4 (0 to 28) days and the overall survival to discharge rate was 78%.
There were 24 male and 15 female cats (sex not recorded in 2 cats). The median (range) age was 3 (0.1 to 12) years, pre-operative stay 1 (0 to 6) days, post-operative stay 5 (0 to 15) days and the overall survival to discharge rate was 85%. Causes of post-operative deaths among animals in the most common categories are recorded and discussed.     

Traumatic diaphragmatic hernia in cats: 34 cases (1991-2001)

OBJECTIVE: To determine whether signalment, duration of hernia, clinical signs, contents of hernia, CBC and serum biochemical abnormalities, concurrent injuries, perioperative treatment and administration of analgesics, results of intraoperative anesthetic monitoring data, or level of training of the veterinarian performing the herniorrhaphy was associated with mortality rate after surgical repair of traumatic diaphragmatic hernia in cats. DESIGN: Retrospective study. ANIMALS: 34 cats. PROCEDURE: Review of medical records and a telephone follow-up with owners and referring veterinarians were performed. RESULTS: Mean age of affected cats was 3.6 years; cats that survived to the time of discharge were significantly younger than cats that died or were euthanatized. Tachypnee was the most common clinical sign at hospital admission; cats that survived to the time of discharge had significantly higher respiratory rates than cats that died or were euthanatized after surgery. Postoperative complications developed in 50% of cats; tachypnea and dyspnea were most common. Mortality rate was not associated with duration of hernia or results of preoperative CBC and serum biochemical analyses, but was significantly associated with concurrent injuries. Mortality rate was not associated with hernia contents, intraoperative use of positive inotropes or corticosteroids, episodes of hypotension or severe hypoxia during anesthesia, or level of training of the veterinarian performing the surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Cats that are older or have low to mildly increased respiratory rates and concurrent injuries are more likely to die after surgical repair of traumatic diaphragmatic hernia.     

Survival Following Cardiopulmonary Resuscitation in Dogs and Cats

Dogs and cats receiving cardiopulmonary resuscitation (CPR) were evaluated for factors leading to cardiac arrest and for survival following the procedure. One-hundred-thirty-five canine and forty-three feline patients seen at the University of California, Davis Veterinary Medical Teaching Hospital that received CPR between August 1987 and December 1991 were studied. Initial resuscitation attempts were unsuccessful in 72% of dogs and 58% of cats. Five dogs and one cat were still alive 3 days after CPR. Ultimately only four dogs and one cat were discharged from the hospital alive. These five patients with uniquely longer survival all had cardiac arrests associated with drug and/or anesthetic reactions.     

Outcome of and prognostic indicators for dogs and cats with pneumoperitoneum and no history of penetrating trauma: 54 cases (1988-2002)

OBJECTIVE: To determine the outcome of and prognostic indicators for dogs and cats with pneumoperitoneum and no history of penetrating trauma. DESIGN: Retrospective study. ANIMALS: 43 dogs and 11 cats. PROCEDURE: Medical records of dogs and cats with radiographic evidence of pneumoperitoneum and no history of penetrating trauma were reviewed. Information collected included signalment, previous medical problems, initial complaint, duration of illness, physical examination findings, radiographic findings, laboratory abnormalities, abdominocentesis results, bacterial culture results, concurrent diseases, hospitalization time, and outcome. Abdominal radiographs were reviewed, and radiographic severity of pneumoperitoneum was classified. For those animals that underwent exploratory laparotomy, time from admission to surgery and results of histologic examination of biopsy specimens were recorded. RESULTS: 24 (44%) animals survived and were discharged from the hospital, but none of the variables examined was associated with whether animals survived. Rupture of the gastrointestinal tract was the cause of pneumoperitoneum in 40 animals. However, cause and location of gastrointestinal tract rupture was not associated with whether animals survived. Twenty-three of 40 (58%) animals that underwent exploratory laparotomy survived, compared with only 1 of 14 animals that did not undergo surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that pneumoperitoneum in dogs and cats without any history of penetrating trauma is most commonly associated with rupture of the gastrointestinal tract and requires immediate surgical intervention. Even when appropriate treatment is instituted, the shortterm prognosis is only fair.     

Review of the technique and complications of median J sternotomy in the dog and cat

The surgical and medical records of 67 dogs and nine cats which underwent median sternotomy over a five-year period were reviewed. The indication for median sternotomy and the short and longer term complications were recorded. Twenty-six of the dogs died or were euthanased within 48 hours of the surgery as a consequence of the pre-existing disease or complications of the intrathoracic surgical procedure. A further four dogs were enthanased between 48 hours and 14 days following confirmation of neoplastic processes. Thirty-seven dogs were alive at 14 days; of these, seven dogs (19 per cent) experienced short-term wound complications, including haemorrhage, wound infection, thoracic limb neurological deficits and excessive postoperative discomfort. Of the 37 dogs alive for longer term follow-up, eight dogs (22 per cent) experienced wound complications, including haemorrhage, sternal fracture, sternal osteomyelitis and delayed wound healing. No complications were noted in the cats.     

Indications, management, and outcome of long-term positive-pressure ventilation in dogs and cats: 148 cases (1990-2001)

OBJECTIVE: To determine outcome of positive-pressure ventilation (PPV) for 24 hours or longer and identify factors associated with successful weaning from PPV and survival to hospital discharge in dogs and cats. DESIGN: Retrospective case series. ANIMALS: 124 dogs and 24 cats that received PPV for 24 hours or longer. PROCEDURES: Medical records were reviewed for signalment, primary diagnosis, reason for initiating PPV, measures of oxygenation and ventilation before and during PPV, ventilator settings, complications, duration of PPV, and outcome. Animals were categorized into 1 of 3 groups on the basis of the reason for PPV. RESULTS: Group 1 patients received PPV for inadequate oxygenation (67 dogs and 6 cats), group 2 for inadequate ventilation (46 dogs and 16 cats), and group 3 for inadequate oxygenation and ventilation (11 dogs and 2 cats). Of the group 1 animals, 36% (26/73) were weaned from PPV and 22% (16/73) survived to hospital discharge. In group 2, 50% (31/62) were weaned from PPV and 39% (24/62) survived to hospital discharge. In group 3, 3 of 13 were weaned from PPV and 1 of 13 survived to hospital discharge. Likelihood of successful weaning and survival to hospital discharge were significantly higher for group 2 animals, and cats had a significantly lower likelihood of successful weaning from PPV, compared with dogs. Median duration of PPV was 48 hours (range, 24 to 356 hours) and was not associated with outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that long-term PPV is practical and successful in dogs and cats.     

Evaluation of intravenous administration of meloxicam for perioperative pain management following stifle joint surgery in dogs

OBJECTIVE: To compare preoperative administration of meloxicam and butorphanol to perioperative administration of butorphanol alone for control of postoperative signs of pain in dogs. ANIMALS: 40 client-owned dogs scheduled for surgical repair of a cranial cruciate ligament rupture. PROCEDURE: Group-1 dogs received butorphanol (0.2 mg/kg, IV) and meloxicam (0.2 mg/kg, IV) just prior to surgery. Group-2 dogs received butorphanol just prior to surgery (0.2 mg/kg, IV) and at incision closure (0.1 mg/kg, IV). Pain assessment began 1 to 2 hours before surgery and from extubation until 24 hours after surgery by obtaining the following measurements: the visual analog scale (VAS) score, cumulative pain score (CPS), adjusted cumulative pain score, modified cumulative pain score, and the adjusted modified cumulative pain score (AMCPS). Serum cortisol concentration was measured between 12 to 24 and between 1 to 2 hours prior to surgery, and at 30 minutes, and 1, 2, 4, 8, 18, and 24 hours after extubation. RESULTS: No significant differences between treatment groups were observed in CPS or VAS score. At 8, 9, 10, and 11 hours after extubation, meloxicam-butorphanol-treated dogs had a significantly lower AMCPS, compared with butorphanol-alone-treated dogs. Total serum cortisol concentration (area under the curve) during the measurement period was significantly lower in meloxicam-butorphanol-treated dogs, compared with butorphanol-alone treated dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Preoperative single dose administration of meloxicam-butorphanol is equivalent to or slightly better than the administration of 2 perioperative doses of butorphanol for the control of postoperative signs of pain in dogs.     

Chronic diaphragmatic hernia in 34 dogs and 16 cats

Medical records of 34 dogs and 16 cats undergoing surgical repair of diaphragmatic hernia of >2 weeks' duration were reviewed, and long-term follow-up information was obtained. The most common clinical signs were dyspnea and vomiting; however, many of the animals were presented for nonspecific signs such as anorexia, lethargy, and weight loss. Thoracic radiographs revealed evidence of diaphragmatic hernia in only 66% of the animals, and additional imaging tests were often needed to confirm the diagnosis. Thirty-six hernias were repaired through a midline laparotomy; 14 required a median sternotomy combined with a laparotomy. In 14 animals, division of mature adhesions of the lungs or diaphragm to the herniated organs was necessary to permit reduction of the hernia. Fourteen animals required resection of portions of the lungs, liver, or intestine. All hernias were sutured primarily without the use of tissue flaps or mesh implants. Twenty-one of the animals developed transient complications in the postoperative period; the most common of these was pneumothorax. The mortality rate was 14%. Thirty-four (79%) of the animals that were discharged from the hospital had complete resolution of clinical signs, and none developed evidence of recurrent diaphragmatic hernia during the follow-up period. Nine were lost to follow-up.     

Extensive small bowel resection in dogs and cats: 20 cases (1998-2004)

OBJECTIVE: To determine outcome in dogs and cats that underwent extensive (ie, > 50%) resection of the small intestine and identify factors associated with outcome. DESIGN: Retrospective case series. ANIMALS: 13 dogs and 7 cats. PROCEDURE: Medical records were reviewed, and follow-up information was obtained. RESULTS: In all 7 cats and in 8 of the 13 dogs, extensive intestinal resection was performed because of a foreign body. Mean+/-SD estimated percentage of intestine that was removed was 68+/-14% (range, 50% to 90%). Two dogs were euthanized 3 days after surgery because of dehiscence of the surgical site and development of septic peritonitis; 1 dog died of acute respiratory distress syndrome 5 days after surgery. The remaining 10 dogs and 7 cats were discharged from the hospital, and follow-up information was available for 15 of the 17. Median survival time was 828 days, and 12 of the 15 animals for which long-term follow-up information was available had good outcomes. However, none of the factors examined, including percentage of intestine resected, were significantly associated with outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Most dogs and cats that underwent extensive resection of the small intestine had a good outcome. The amount of intestine resected was not associated with outcome. These data may be useful in providing prognostic information in cases of extensive small intestinal resection.     

Tracheal rupture associated with intubation in cats: 20 cases (1996-1998)

OBJECTIVE: To characterize clinical features of tracheal rupture associated with endotracheal intubation in cats and to evaluate the most appropriate treatment for this condition. DESIGN: Retrospective study. ANIMALS: 20 cats with a history of endotracheal intubation that subsequently developed dyspnea or subcutaneous emphysema. PROCEDURE: Medical records of cats with a presumptive diagnosis of tracheal rupture associated with intubation were reviewed. Clinical and clinicopathologic data were retrieved. RESULTS: Cats were evaluated 5 hours to 12 days after a surgical or medical procedure requiring general anesthesia with intubation had been performed. Fourteen (70%) cats were evaluated after dental prophylaxis. All cats radiographed had pneumomediastinum and subcutaneous emphysema. Eighteen of 19 cats were initially treated medically. Duration of medical treatment for cats that did not have surgery ranged from 12 to 72 hours. Cats that had surgery received medical treatment 3 to 24 hours prior to the surgical procedure. Medical treatment alone was administered to 15 cats that had moderate dyspnea, whereas surgical treatment was chosen for 4 cats that had severe dyspnea (open-mouth breathing despite treatment with oxygen) or worsening subcutaneous emphysema. Eighteen cats had improvement of clinical signs, 1 cat died after surgery, and 1 cat died before medical or surgical intervention. CONCLUSIONS AND CLINICAL RELEVANCE: Most cats with tracheal rupture associated with intubation can be treated medically. Cats with worsening clinical signs (severe dyspnea, suspected pneumothorax, or worsening subcutaneous emphysema) should have surgery performed immediately to correct the defect.     

Perioperative administration of antimicrobials associated with elective surgery for cranial cruciate ligament rupture in dogs: 83 cases (2003-2005)

OBJECTIVE: To evaluate perioperative antimicrobial use associated with elective surgery for cranial cruciate ligament rupture in dogs. DESIGN: Retrospective case series. ANIMALS: 83 dogs. PROCEDURES: Medical records were reviewed and antimicrobial use practices were evaluated for dogs with no other problems that would affect antimicrobial use decisions. RESULTS: Antimicrobials were administered before or during surgery to 75 of 83 (90%) dogs. Timing of administration with respect to first incision, intraoperative administration, and duration of administration were variable. Antimicrobial administration began after surgery in 3 (3.6%) dogs. Fifty-five of 65 (85%) dogs treated before surgery received the first dose within 60 minutes of the first incision. Time from first antimicrobial administration to closure of the incision ranged from 15 to 285 minutes (mean +/- SD, 141 +/- 53 minutes). If a guideline of repeated administration every 2 hours after first administration until closure of the surgical site was used, 22 of 43 (51%) dogs received the required intraoperative dose, whereas 6 of 32 (19%) dogs that did not require intraoperative treatment were treated. Twenty-four (29%) dogs received antimicrobials after surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Certain discrepancies between antimicrobial use practices in this study and standard guidelines used in human medicine were evident.     

Clinical Determination of Preoperative and Postoperative Intra-abdominal Pressures in Dogs

Intra-abdominal pressure (IAP) was indirectly measured, using a transurethral catheterization technique, in 20 client-owned dogs before and after elective ovariohysterectomy. Mean preoperative IAP was 4.50 ± 0.44 cm H₂O. Elective abdominal surgery caused significant elevations in mean postoperative IAP (mean 7.50 ± 0.45 cm H₂O, range 0 to 15 cm H₂O) that persisted for at least 24 hours. However, the increase in IAP caused no clinically evident complications; thus, after elective abdominal surgery an elevation in IAP up to 15 cm H₂O is to be expected. Intra-abdominal pressure was also measured in 20 consecutive clinical cases with gross abdominal distension, before or after laparotomy, or both. Included in this group were dogs with gastric dilation and volvulus, closed pyometra, hemoperitoneum, acute ascites, and diaphragmatic hernias. All dogs with gross abdominal distension had an elevated IAP (> 16 cm H₂O) either before or after surgery. Severe elevations of IAP were associated with anuria in two dogs, necessitating surgical decompression; one with hemoperitoneum (47 cm H₂O) and one after repair of a chronic diaphragmatic hernia (30 cm H₂O).     

Peritoneopericardial diaphragmatic hernia: a retrospective study of 31 cats and eight dogs

The records of 31 cats and eight dogs undergoing surgical correction of peritoneopericardial diaphragmatic hernia (PPDH) from 2000 through 2007 were reviewed. Weimaraners and long-haired cats of varying breeds, particularly Maine Coon cats, appear to be at higher risk of PPDH. Presenting complaints were most commonly related to the respiratory and gastrointestinal tracts in both dogs and cats, although respiratory signs were more prevalent in cats, and gastrointestinal signs were more common in dogs. The most common herniated organs were liver, gallbladder, and small intestine. Mortality associated with surgical repair of PPDH in cats and dogs was low in the first 2 weeks postoperatively, and prognosis for return to normal function was excellent. Peri-and postoperative complications were typically minor and self-limiting.     

Autologous blood collection and transfusion in cats undergoing partial craniectomy

OBJECTIVE: To describe the procedure for autologous blood donation and associated complications in cats undergoing partial craniectomy for mass removal. DESIGN: Prospective case series. ANIMALS: 15 cats with intracranial mass confirmed by computed tomographic scan, no evidence of renal failure, and PCV > or = 22%. PROCEDURE: One unit (60 ml) of blood was collected and stored 7 to 17 days before surgery and transfused during the perioperative period if needed. The PCV was measured before donation, before surgery, during surgery, and after surgery to assess effect of donation on PCV before surgery and effect of transfusion on PCV after surgery. Cats were evaluated for donation complications, iatrogenic anemia, and adverse reactions associated with administration of autologous blood. RESULTS: Complications associated with phlebotomy were not detected. Fifteen cats underwent partial craniectomy 7 to 17 days after blood donation; all had histologic confirmation of meningioma by examination of tissue obtained at surgery. Eleven cats received autologous blood transfusions. None of the cats received allogeneic blood transfusions. Transfusion reactions were not observed. Subclinical iatrogenic anemia was detected in 3 cats. Two cats were considered to have received excessive transfusion, and 3 cats received inadequate transfusion. All cats undergoing partial craniectomy were discharged from the hospital and were alive > 6 months after surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Autologous blood donation before surgery was considered safe for cats undergoing partial craniectomy for resection of meningioma. The only complication observed was iatrogenic anemia. The procedure contributed to blood conservation in our hospital.     

The Association of Propofol Usage With Postoperative Wound Infection Rate in Clean Wounds: A Retrospective Study

OBJECTIVE: To determine if the use of propofol influences the postoperative infection rate of clean surgical wounds in dogs and cats. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: 863 dogs and cats undergoing clean surgical procedures. METHODS: Medical and anesthetic records of surgical cases used as part of a previously described epidemiologic study on postoperative wound infection rates were reviewed. The records of all animals with clean surgical wounds were reviewed to determine if propofol had been used for anesthetic induction or maintenance during the procedure. To determine the effect of propofol use on wound infection rate, data were analyzed using Fisher's exact test, followed by multiple logistic regression to adjust for various factors, including surgery time, time from clipping to surgery, antibiotic usage, coexisting distant infection, endocrine disease, and the use of immunosuppressive drugs in the perioperative period. RESULTS AND CONCLUSIONS: Of 863 dogs and cats with clean surgical wounds, 46 received propofol as part of the anesthetic protocol. A total of 6 of 46 animals (13%) receiving propofol developed postoperative wound infections, compared with 33 of 817 animals (4%) not receiving propofol (P = .014; % difference = 9%; 95% CI = 0.5% to 24%). Adjusting for all other factors evaluated, animals receiving propofol were 3.8 times more likely to develop postoperative wound infections compared to animals not given propofol (95% CI = 1.5-9.9). CLINICAL IMPLICATIONS: Propofol is a lipid-based emulsion capable of supporting microbial growth. Administration of a potentially contaminated solution may contribute to surgical wound infection or other patient morbidity or mortality. Strict aseptic technique in the preparation of the solution and prompt disposal of unused drug are imperative to curtail the potential for extrinsic contamination.     

Use of low doses of ketamine administered by constant rate infusion as an adjunct for postoperative analgesia in dogs

OBJECTIVE: To compare indicators of postoperative pain and behavior in dogs with and without a low-dose ketamine infusion added to usual perioperative management. DESIGN: Prospective, randomized, blinded clinical study. ANIMALS: 27 dogs undergoing forelimb amputation. PROCEDURE: Dogs were anesthetized with glycopyrrolate, morphine, propofol, and isoflurane. Thirteen dogs were treated with ketamine IV, as follows: 0.5 mg/kg (0.23 mg/lb) as a bolus before surgery, 10 microg/kg/min (4.5 microg/lb/min) during surgery, and 2 microg/kg/min (0.9 microg/lb/min) for 18 hours after surgery. Fourteen dogs received the same volume of saline (0.9% NaCl) solution. All dogs received an infusion of fentanyl (1 to 5 microg/kg/h [0.45 to 2.27 pg/lb/h]) for the first 18 hours after surgery. Dogs were evaluated for signs of pain before surgery, at the time of extubation, and 1, 2, 3, 4, 12, and 18 hours after extubation. Owners evaluated their dogs' appetite, activity, and wound soreness on postoperative days 2, 3, and 4. RESULTS: Dogs that received ketamine infusions had significantly lower pain scores 12 and 18 hours after surgery and were significantly more active on postoperative day 3 than dogs that received saline solution infusions. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that perioperative administration of low doses of ketamine to dogs may augment analgesia and comfort in the postoperative surgical period.     

Long-term outcome of cats treated conservatively or surgically for peritoneopericardial diaphragmatic hernia: 66 cases (1987-2002)

OBJECTIVE: To determine long-term outcome of cats treated conservatively or surgically for peritoneopericardial diaphragmatic hernia (PPDH). DESIGN: Retrospective study. ANIMALS: 67 cats with PPDH. PROCEDURE: Medical records of cats with a diagnosis of PPDH made from 1987 through 2002 were reviewed. Information regarding long-term outcome was obtained from owners. RESULTS: Prevalences of PPDH in domestic longhair and Himalayan cats were significantly greater and prevalence of PPDH in domestic shorthair cats was significantly lower than prevalence of PPDH in the hospital cat population over the 15-year study period. Historical problems most commonly related to the respiratory and gastrointestinal tracts. Peritoneopericardial diaphragmatic hernia was the primary diagnosis in 40 cats and an incidental finding in 27 cats. One cat died prior to arrival at the Veterinary Medical Teaching Hospital. Thirty-seven of 66 cats were treated surgically, and 29 were treated conservatively. The postoperative mortality rate was 14%. Postoperative complications developed in 29 of 37 cats, the most common of which was hyperthermia. Two of 22 conservatively treated cats had progression of clinical signs necessitating surgical intervention or resulting in death. Owner satisfaction with treatment choice and long-term outcome was rated as very satisfied by 88% of owners of surgically treated cats and 68% of owners of conservatively treated cats. CONCLUSIONS AND CLINICAL RELEVANCE: Cats with overt clinical signs attributable to PPDH are good candidates for surgical herniorrhaphy. Postoperative complications may develop but are generally minor and self-limiting. Long-term outcome of cats treated conservatively or surgically was rated as very good by most owners.     

Intrahepatic Portosystemic Venous Anomaly in the Dog Perioperative Management and Complications

Hypotension, hemorrhage, and acute hepatic congestion were common complications during surgical correction of intrahepatic portosystemic venous anomalies in 13 dogs. Acute splanchnic congestion and hyperthermia were the most serious postoperative complications. Three dogs died within 24 hours; 10 dogs are alive and well after 12 to 46 months.