Elective neutering of dogs and cats is the most commonly performed surgical procedure in veterinary practice. For females, surgeons can choose between ovariectomy and ovariohysterectomy. Several authors have argued that ovariectomy should be the method of choice because it is considered to be less invasive, faster, safer, and associated with fewer postoperative complications.1–4 However, few randomized studies have been conducted to compare ovariectomy and ovariohysterectomy, and the authors are not aware of any studies conducted to compare the hemostatic part of the surgical stress response or short-term postoperative morbidity between the 2 procedures.
In humans, the effects of surgery on the hemostatic response and the development of an increased tendency for clot formation (ie, hypercoagulability) are known. Surgery and immobilization are considered some of the risk factors for the development of hypercoagulability and postoperative thromboses.5 The same activation of the hemostatic response has also been reported in horses, as indicated by decreased concentrations of AT and increased concentrations of D-dimer.6 Furthermore, decreases in TT, fibrinogen concentration, and AT concentration have been reported in pigs after surgery.7 Clinical evidence of postoperative thromboses is rarely reported in dogs. However, in 1 study,8 the incidence of subclinical pulmonary emboli in dogs 48 hours after total hip replacement was 82%, a finding that warrants further research in this field.
Complications after elective surgery are not uncommon and have been reported to include hemorrhage, inflammation or infection of the surgical site, and a need for increased attention to the surgical site.9,10 The importance of the hemostatic response in the development of such complications is largely undetermined. However, there is evidence that greater surgical trauma leads to an increased hemostatic response in dogs as well as humans.11–14 Investigators in 1 study12 reported a transient decrease in plasminogen concentration and increased concentrations of α-2-antiplasmin (plasmin inhibitor) in dogs after major surgery, whereas no significant response was detected in dogs after elective surgery. Several studies in humans indicated a procoagulant response to surgery. A decrease in PT and TT and an increase in aPTT, protein C concentration, and D-dimer concentration after surgery were reported in humans undergoing 4 types of surgery that differed with regard to surgical invasiveness.14 In that study,14 fibrinogen concentrations decreased the day after surgery before gradually increasing. Overall, the changes were most pronounced after a more invasive surgery, such as total hip replacement and hemicolectomy, but some variables changed significantly, although the changes were less pronounced, after less invasive procedures, such as endoscopic cholecystectomy and subtotal thyroid resection. In another study,13 AT concentration was the most sensitive marker for the degree of surgical trauma in humans.
Studies12,15 of surgery on dogs have involved the use of assays that assess only isolated parts or phases of the hemostatic process, and it has been difficult to evaluate the entire coagulant state. Thromboelastography performed on whole blood allows for global assessment of hemostatic function from initiation of clotting through amplification and propagation of clot formation to fibrinolysis. Although the equipment for thromboelastography is highly specialized and not readily available to all clinicians, it may be a valuable addition for the diagnosis of hemostatic disorders and assessment of hypercoagulability.16–18 Thromboelastography most commonly involves the use of whole blood but may be applied to frozen-thawed plasma samples.17 This allows for analysis of the samples in a single assay and has the added benefit of eliminating between-assay analytic variation.
The primary objective of the study reported here was to investigate the effects of elective surgery on the hemostatic response in dogs, including whether hypercoagulability is induced, and to compare the magnitude of this response in dogs in which surgical trauma was believed to be minimal (ovariectomy) with that in dogs in which the trauma was believed to be greater (ovariohysterectomy). Our hypothesis was that ovariectomy would have a less pronounced effect on the hemostatic response, compared with the effect for ovariohysterectomy, as measured via plasma thromboelastography, coagulation tests, and fibrinolysis tests. The secondary objective of the study reported here was to evaluate the use of plasma thromboelastography for measuring hemostatic trends over time.
Activated partial thromboplastin time
Domitor, 1 mg/mL, Pfizer Animal Health, New York, NY.
Rimadyl, 50 mg/mL, Pfizer Animal Health, New York, NY.
PropoVet, 10 mg/mL, Abbott Laboratories, Queenborough, Kent, England.
Isoflo, Abbott Laboratories, Queenborough, Kent, England.
Stereofundin, Iso, B Braun, Melsungen, Germany.
Antisedan, 5 mg/mL, Pfizer Animal Health, New York, NY.
Buprecare, 0.3 mg/mL, Animalcare Ltd, Dunnington, York, England.
Tissue factor, Innovin, Dade Behring, Milton Keynes, Buckinghamshire, England.
TEG 5000 hemostasis analyzer, Haemoscope Corp, Niles, Ill.
ACL 9000, Instrumentation Laboratory, Bedford, Mass.
Nycocard Reader II, Medinor A/S, Oslo, Norway.
Stata, version 11, Statacorp, College Station, Tex.
Janssens LAAJanssens GHRR. Bilateral flank OVE in the dog—surgical technique and sequelae in 72 animals. J Small Anim Pract 1991; 32:249–252.
Okkens ACVandergaag IBiewenga WJ, et al. Urological complications following OHE in dogs. Tijdschr Diergeneeskd 1981; 106:1189–1198.
Okkens ACKooistra HSNickel RF. Comparison of long-term effects of OVE versus OHE in bitches. J Reprod Fertil Suppl1997;(51):227–231.
van Goethem BSchaefers-Okkens AKirpensteijn J. Making a rational choice between OVE and OHE in the dog: a discussion of the benefits of either technique. Vet Surg 2006; 35:136–143.
Feige KKastne SBRDempfle CE, et al. Changes in coagulation and markers of fibrinolysis in horses undergoing colic surgery. J Vet Med A Physiol Pathol Clin Med 2003; 50:30–36.
Palsgaard-Van Lue AStrom HLee MH, et al. Cellular, hemostatic, and inflammatory variables of the surgical stress response in pigs undergoing partial pericardectomy via open thoracotomy or thoracoscopy. Surg Endosc 2007; 21:785–792.
Burrow RBatchelor DCripps P. Complications observed during and after OHE of 142 bitches at a veterinary teaching hospital. Vet Rec 2005; 157:829–833.
Pollari FLBonnett BN. Evaluation of postoperative complications following elective surgeries of dogs and cats at private practices using computer records. Can Vet J 1996; 37:672–678.
Kambayashi JSakon MYokota M, et al. Activation of coagulation and fibrinolysis during surgery, analyzed by molecular markers. Thromb Res 1990; 60:157–167.
Lanevschi AKramer JWGreene SA, et al. Fibrinolytic activity in dogs after surgically induced trauma. Am J Vet Res 1996; 57:1137–1140.
Siemens HJGBrueckner SHagelberg S, et al. Course of molecular hemostatic markers during and after different surgical procedures. J Clin Anesth 1999; 11:622–629.
Millis DLHauptman JGRichter M. Preoperative and postoperative hemostatic profiles of dogs undergoing OHE. Cornell Vet 1992; 82:465–470.
Donahue SMOtto CM. TEG: a tool for measuring hypercoagulability, hypocoagulability, and fibrinolysis. J Vet Emerg Crit Care 2005; 15:9–16.
Wiinberg BJensen ALKjelgaard-Hansen M, et al. Study on biological variation of haemostatic variables in clinically healthy dogs. Vet J 2007; 174:62–68.
Wiinberg BJensen ALJohansson PI, et al. Thromboelastographic evaluation of hemostatic function in dogs with disseminated intravascular coagulation. J Vet Intern Med 2008; 22:357–365.
Peeters MKirpensteijn J. Comparison of surgical variables and short-term postoperative complications in dogs undergoing ovariohysterectomy or ovariectomy. J Am Vet Med Assoc 2011; 238:189–194.
Holton LReid JScott EM, et al. Development of a behaviour-based scale to measure acute pain in dogs. Vet Rec 2001; 148:525–531.
Wiinberg BJensen ALRojkjaer R, et al. Validation of human recombinant tissue factor-activated TEG on citrated whole blood from clinically healthy dogs. Vet Clin Pathol 2005; 34:389–393.
Kristensen ATWiinberg BJessen LR, et al. Evaluation of human recombinant tissue factor-activated TEG in 49 dogs with neoplasia. J Vet Intern Med 2008; 22:140–147.
Dohoo IMartin WStryhn H. Mixed models for continuous data. In: Veterinary epidemiologic research. 2nd ed. Charlottetown, PE, Canada: VER Inc, 2009:553–565.
Freyburger GDubreuil MAudebert A, et al. Changes in haemostasis after laparoscopic surgery in gynaecology: contribution of the thrombin generation test. Haemostasis 2001; 31:32–41.
Ceron JJEckersall PDMartynez-Subiela S. Acute phase proteins in dogs and cats: current knowledge and future perspectives. Vet Clin Pathol 2005; 34:85–99.
Singer IOPringle STait RC, et al. Hysterectomy techniques and their effect on the blood markers of thrombogenicity. Gynaecol Endosc 2000; 9:379–383.
Stokol T. Plasma D-dimer for the diagnosis of thromboembolic disorders in dogs. Vet Clin North Am Small Anim Pract 2003; 33:1419–1435.
Bongard OWicky JPeter R, et al. D-dimer plasma measurement in patients undergoing major hip-surgery: use in the prediction and diagnosis of postoperative proximal vein-thrombosis. Thromb Res 1994; 74:487–493.
Bounameaux HDemoerloose PPerrier A, et al. Plasma measurement of D-dimer as diagnostic-aid in suspected venous thromboembolism: an overview. Thromb Haemost 1994; 71:1–6.
Nelson OLAndreasen C. The utility of plasma D-dimer to identify thromboembolic disease in dogs. J Vet Intern Med 2003; 17:830–834.
Baxter GMParks AHPrasse KW. Effects of exploratory laparotomy on plasma and peritoneal coagulation fibrinolysis in horses. Am J Vet Res 1991; 52:1121–1127.
Lang IMMarsh JJKonopka RG, et al. Factors contributing to increased vascular fibrinolytic activity in mongrel dogs. Circulation 1993; 87:1990–2000.
Lopez YParamo JAValenti JR, et al. Hemostatic markers in surgery: a different fibrinolytic activity may be of pathophysiological significance in orthopedic versus abdominal surgery. Int J Clin Lab Res 1997; 27:233–237.
Prisco DDe Gaudio ARCarla R, et al. Videolaparoscopic cholecystectomy induces a hemostasis activation of lower grade than does open surgery. Surg Endosc 2000; 14:170–174.
Devitt CMCox REHailey JJ. Duration, complications, stress, and pain of open OHE versus a simple method of laparoscopic-assisted OHE in dogs. J Am Vet Med Assoc 2005; 227:921–927.
Wirtz PHEhlert UEmini L, et al. The role of stress hormones in the relationship between resting blood pressure and coagulation activity. J Hypertens 2006; 24:2409–2416.
Zgraggen LFischer JEMischler K, et al. Relationship between hemoconcentration and blood coagulation responses to acute mental stress. Thromb Res 2005; 115:175–183.
Günzel-Apel ARHayer MMischke R, et al. Dynamics of haemostasis during the oestrous cycle and pregnancy in bitches. J Reprod Fertil Suppl1997;(51):185–193.