Greater Swiss Mountain Dog Postoperative Hemorrhage (P2Y12)
Greater Swiss Mountain Dog Postoperative Hemorrhage (P2Y12) is a newly identified hereditary disorder of platelets characterized with excessive postoperative bleeding. Similar bleeding disorder caused by mutation within same gene has been identified in human patients.
Platelets are also known as thrombocytes, and they have a key role in bleeding prevention through clumping of blood vessel injuries. At a site of vascular injury, platelets are exposed to surface which is not from blood vessel, and they initiate to aggregate to each other, which results in formation of a hemostatic plug that will seal the defect. The platelet P2Y12 receptor for adenosine 5’diphosphate (ADP) has a key role in platelet function, hemostasis, and thrombosis. Other than that, P2Y12 takes place also in inflammation processes. It has been observed that patients with inherited P2Y12 defects are prone to mild-to-moderate bleeding. Biochemically, P2Y12 defects suspected when even at high concentrations ADP is unable to induce full platelet aggregation.
Agents that can induce affinity of the integrin for fibrinogen are ADP, collagen, thromboxane, and thrombin. Unfortunately, in case of bleeding disorders, these agents do not have an effect on platelet aggregation.
Characteristics and Symptoms
Affected dogs show no abnormalities on physical examination. Dog may go through life event, such as whelping, vaccinations, deworming or microchip implantation, with no reported problems. Excessive, severe and prolonged bleeding occurs after trauma or minor cut, nail trimming, or during eruption of adult teeth. Problems occur after operation. Mucous membranes appear as pale and dog is weak, with severe bruising around the incision line. Collection of peritoneal fluid and its examination reveals internal bleeding. Hematoma can be found within the body, and in one affected dog hematoma was present near 1 ovarian pedicle. Spontaneous bleeding is usually not encountered in affected dogs.
Greater Swiss Mountain Dog Postoperative Hemorrhage (P2Y12) is caused by a mutation encoding for platelet P2Y12 receptor. The detected mutation involves 3 base-pair deletion. The disorder is inherited in an autosomal recessive pattern. Dog can be clear, carrier of affected. Dog carrying one copy of the mutated gene is heterozygous and will not show the postoperative hemorrhage symptoms. When mating two carriers (heterozygotes) at conception each cub has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.