A 3-year-old, female Greater Swiss Mountain dog developed a hemoperitoneum following an exploratory laparotomy and ovariohysterectomy. Platelet count, PT, APTT, and plasma von Willebrand factor antigen concentration were within RIs. A buccal mucosal bleeding time (BMBT) was prolonged. Given the probability of a hereditary thrombopathia, the dog was administered desmopressin, fresh platelet transfusions, and aminocaproic acid to control hemorrhage. Subsequently, DNA testing for the P2Y12 receptor gene mutation identified the dog as being a heterozygote (carrier). Further platelet function testing was performed following complete recovery. Results of a repeat BMBT and a point-of-care screening test using the Platelet Function Analyzer-100 (collagen/adenosine-diphosphate [ADP] test cartridge) were within RIs. Flow cytometric studies demonstrated a marked reduction in fibrinogen binding to the dog's platelets in response to ADP -adenosine diphosphate activation. Likewise, turbidimetric aggregometry revealed a complete absence of platelet aggregation in response to ADP. However, there were a normal aggregation response to the platelet agonist convulxin and a mild reduction in amplitude in response to c-thrombin. This is the first report of a dog heterozygous for the P2Y12 receptor gene mutation exhibiting a bleeding tendency and having evidence of impaired platelet function in vitro in response to ADP activation. Given that the mutant allele for the P2Y12 thrombopathia appears to be widespread in the Greater Swiss Mountain dog breed, veterinarians need to be aware that both homozygotes and heterozygotes for this platelet receptor mutation are at risk of developing life-threatening bleeding following trauma or surgery.
Case PresentationA 3-year-old, intact female, Greater Swiss Mountain dog was presented to the Matthew J. Ryan Veterinary Hospital of the University of Pennsylvania for gastrointestinal biopsies and a routine ovariohysterectomy (OVH). The dog had a 9-month history of vomiting, large bowel diarrhea, and weight loss that were minimally responsive to metronidazole, tylosin, and a diet change. Initial diagnostic evaluation included a CBC, serum chemistry profile, adrenocorticotropic hormone (ACTH) stimulation test, and serum cobalamin and folate concentrations, with all results within RIs. A zinc sulfate fecal flotation was negative for parasites. An abdominal ultrasonographic examination revealed small intestinal submucosal thickening and mesenteric and iliac lymphadenopathy.Preoperative PCV and total protein (TP) were 45% (RI 40-60%) and 6.0 g/dL (RI 5.5-7.5 g/dL), respectively. The dog was placed under general anesthesia, and a colonoscopy with colonic biopsies was performed, followed by an exploratory laparotomy with full thickness biopsies of the duodenum, jejunum, and ileum, and an OVH. The procedures were uncomplicated; however, mild oozing of blood was noted from the skin incision, body wall, and multiple surfaces within the abdomen. One day postoperatively, tachycardia, pallor, and a moder...
