Anesthesia in cats and dogs with bleeding disorders

Tag : rodenticides
The main concern for pre-operative preparation in the bleedingdisorder patient is sufficient deficient factors or blood to ensureperioperative hemostasis. Therefore, if at all possible, bleedingdisorder patients should be managed before anesthesia and surgery.The management includes removal of the causes of the acquiredbleeding disorder, administration of blood or blood product therapy , and adjunctive drugs and fluid therapy .
Particular care with intravenous fluid therapy should be taken toavoid exacerbation of the existing problem. Remove or discontinue the agent(s) causing the drug-inducedthrombocytopenia or acquired bleeding disorder, such as aspirin, non-steroidalanti-inflammatory drugs, or rodenticides. Underlying causes such as uremia, liver dysfunction, neoplasia,sepsis, systemic infection, pyometra, gastric dilatation-volvulus,or intestinal obstruction are likely to induce a bleeding disorder.Intestinal obstruction and biliary stasis or blockage may result invitamin K deficiency. Liver dysfunction impairs all coagulationfactors. Transfusion of whole blood or blood products (platelets and plasma)supplies the defective patients with functional platelets or withspecific plasma factors. For those patients with active bleeding or for prevention ofintra-operative bleeding during a minor or short duration surgery,a single transfusion, of appropriate volume and type, beforesurgery may be sufficient. For those patients undergoing a major or prolonged surgery,multiple transfusions beginning before surgery and continuingduring surgery through recovery until 1-3 days after surgery areoften necessary. Transfusion of whole blood or blood products is necessary when thepacked cell volume (PCV ) is less than 20 percent. Short duration anesthesia has beenperformed with chronic bleeding disorder patients of PCV less than20 without significant consequence. However, if a longer durationof anesthesia and surgery are required, a whole blood transfusionis a must. Since not all blood products would be suitable for apatient with abnormally low PCV, it is prudent to considernon-surgical treatment options before performing invasive surgeryfor further blood loss. Fresh or frozen plasma can be transfused at 6-12 ml/kg.Alternatively, fresh whole blood can be used instead. Most dogs (40%) are type A negative and can be considered universaldonors. For a single transfusion in a dog that has never received atransfusion, few reactions occur. However, if time allows, typingof the blood and cross matching is strongly advised. A universal canine blood donor with blood type of DEA-1.1, DEA-1.2and DEA-7 loci should be used for major blood transfusions inhemorrhagic shock or dogs that have received a blood transfusion inthe past. Cross match of the donor red blood cells to recipient'sserum (major match) or donor's serum to recipient's red blood cells(minor match) should be performed prior to major surgery to comparedonor and recipient control red cells and serum. Unlike in dogs, cats must be carefully matched before a bloodtransfusion . As a general rule, fresh whole blood, packed red blood cells,platelet-rich plasma, fresh or frozen plasma can be administered ata rate of 6-12 ml/kg to treat patients with anemia, low platelets,coagulation factor defects or vW disease. Plasma cryoprecipitate (1 U per 10 kg) is best for treatingpatients with hemophilia A, vW disease or fibrinogen deficiency,while cryosupernatent (6-12 ml/kg) is best for treating patientswith hemophilia B or other coagulation factor deficiencies. 200 ml fresh frozen plasma produces only 1 U of cryoprecipitate. In cases of vitamin K deficiency or antagonizing rodenticidetoxicity , vitamin K (5 mg/kg) can be given subcutaneously in multiplesites. The therapy should be used together with blood or bloodproduct transfusion for best outcome. Desmopressin acetate (DDAVP ) is a drug to treat vW disease. DDAVP stimulates releases of vWfactors from endothelial stores. The DDAVP is reported to increase40% of vW factor concentrations in donor dogs (4). DDAVP can beadministered via injection or intra-nasal spray at a dose of 1µg/kg 30-60 minutes before collecting blood from a donor dogfor a recipient with vW disease. DDAVP (1 µg/kg, SC) can be given directly to animals withType I or Type II vW disease 30 minutes before the surgery toincrease the release of endothelial stores of the factors and mayshorten the bleeding time.