State of the hemostatic system in transmissible venereal sarcoma of dogs

Abstract

Transmissible venereal sarcoma of dogs is a fairly common problem in the gynecology of these animals. It causes deterioration of reproductive function, leads to intoxication of the body, and in case of extreme growth can provide mechanical barriers to urination etc. Special attention of specialists of veterinary medicine is a significant tendency to increase the intensity of morbidity of animals, the development of complications and the involvement of the whole body in the pathological process. The study of complications in our time is one of the topical problems of dogs gynecology with the aim of preserving of reproductive capacity of animals and their health.

Transmissible venereal sarcoma of dogs is transmissible histiocytic tumor of the external genitals of dogs and other canines. Tumor cells are transmitted between animals sexually. It is a malignant formation. Unlike other such tumors, it has no properties to metastasize. Due to the fact that the sarcoma has a certain contagiousness, it is not a tumor in its pure form. At the same time, histologically it is characterized by all the signs of a malignant tumor, in its structure belongs to the group of alveolar sarcomas.

For its development the tumor is having its effect on the homeostasis of the dog. In particular, the products of its metabolism are stimulating factors that contribute to the development of significant changes in the hemostasis system, which are included in the pathogenesis and further involve the entire body in the pathogenic process.

The relationship of tumor development with the state of the hemostatic system is unexplored.

The aim of the study was to identify and study the changes in the hemostatic system during the course of transmissive venereal sarcoma, to establish the symptom complex according to clinical and laboratory parameters, its form and stage.

Blood from sick female dogs was examined. Conducted hematological (hemoglobin content, the number of corpuscles, erythrocyte sedimentation rate, hematocrit value, spontaneous platelet aggregation, spontaneous aggregation capacity of red blood cells), hemostasiological (indexes of coagulogramm, products of "paracoagulation"), biochemical (degradation products of fibrinogen/fibrin, the amount of fibrinogen) study by the underlying uniform methods. Erythrocyte indices were calculated by formulas (https://yadi.sk/d/rdzMqId73He6xg).

In dogs, the patients transmissible venereal sarcoma, clinical examination revealed bleeding from the genital slit, which attracted the attention of their owners. During urination there was unusual posture, and disturbance to the animals. The vaginal examination revealed hyperemia of the mucous membrane of the vaginal and vaginal opening, the cervix and the presence of growths resembling "cauliflower". Sometimes they filled the entire clearance of the vagina.

In the hematological parameters of dogs with venereal sarcoma, revealed significant thrombocytopenia and increased spontaneous platelet aggregation, which indicate thrombosis in the microcirculatory bed and the output of platelets from circulation to blood clots due to their consumption. Along with a significant increase in the content of hemoglobin in the red blood cell and a tendency to increase the average volume of red blood cells, there was also a tendency to increase the color index, which against the background of a decrease in the number of red blood cells indicates a hemolytic process.

According to hemostasiogram indicators, the increase of Z-potential, the difference between the negative electrostatic charge of intima and the positive charge of the platelet surface, is a confirmation of the endothelial integrity violation and the growth of its wettability. Endothelial damage plays a leading role in the occurrence of thrombosis.

         Damage to the vessel wall activates the plasma cascade of blood clotting. In dogs, the patients transmissible venereal sarcoma, hypercoagulation identified in the tests of spontaneous blood coagulation (p < 0.5), the silicone time of blood coagulation (p < 0.001), partial thromboplastin time and activated partial thromboplastin time (p < 0.001). The lengthening of the recalcification time of platelet-free plasma with an increase in the activity of platelet factor 3 almost completely excludes the contact phase of coagulation, as indicated by the negative value of the difference between the time of spontaneous blood coagulation and recalcification of the platelet-free plasma.

An increase in the thrombin index characterizes the process of thrombinemia, which is a leading link in the pathogenesis of acquired hemostasis-syndrome of disseminated intravascular coagulation (DIC). Based on these data, we believe that in patients dogs with transmissible veneral sarcoma the process of thrombin production dominated by an internal mechanism that indicates the predominance of stimulants of contact factor XII Hageman, which probably represent products of metabolism and destruction of the tumor.

Indicators of fibrinolytic activity have a pronounced tendency to a versatile shift – an increase in spontaneous fibrinolysis and a decrease in euglobulin lysis, but these changes are unreliable.

The increase in plasma tolerance to heparin more than 1800 seconds indicates an increase in anticoagulant activity, which may occur due to an increase of endogenous anticoagulants in the circulation, which are modified plasma globulines.

Degradation products of fibrinogen / fibrin and soluble fibrin-monomeric complexes are evidence of secondary fibrinolysis and significantly higher in sick dogs, which is an unequivocal marker of acquired hemostasiopathy – DIC. Along with this, there is a tendency to hypofibrinogenemia, which is also characteristic of this pathology.

Determination of the form of DIC syndrome and its stage is characterized by shifts in coagulation tests. The divergence of such is pathognomonic for the II stage of the process – consumption coagulopathy, which is established by our studies. The form of the course corresponds to the subacute, and from the clinical signs only bloody discharge from the genital slit can be distinguished.

The appearance of clinical signs, which attracted the attention of pet owners, is under increasing intensity of the process, since the characteristic of tumor thrombocytosis and hyperfibrinogenemia changed to thrombocytopenia and hypofibrinogonemia, determining consumption of cells and factors about the development hemostasiopathy and the tendency towards irreversibility. The very fact of the presence of such a complication indicates the threat of life-threatening changes for the actions of any pathological stimulus, the strength of which will exceed the protective capabilities of the body.

The prospects for further research are in a deeper study of changes in the hemostatic system in the development of transmissive venereal sarcoma of dogs in the dynamic aspect and established diagnostic criteria for the potential danger of irreversible processes. This will also optimize the scheme of conservative treatment of complications at different stages of the disease.