Anaphylactic shock in dogs after vaccination. Anaphylactic shock in cats and dogs. What substances can cause anaphylaxis in dogs

Anaphylaxis(from the Greek ana - a prefix meaning the opposite, opposite action, and phylaxis - protection, protection), a state of increased sensitivity of the body to the repeated introduction of a foreign substance of a protein nature - anaphylactogen; one of the types of allergies.

To induce anaphylaxis, animals are previously sensitized with a specific anaphylactogen (blood serum, egg white, extracts of bacteria and animal organs, plant proteins, etc.). The magnitude of the sensitizing dose of anaphylactogen depends on its quality, type of animal, individual properties of the organism, as well as on the route of administration. The parenteral route of administration of anaphylactogen is most effective; its introduction through the gastrointestinal tract and mucous membranes of the upper respiratory tract is possible. The state of hypersensitivity (sensitization) begins to manifest itself 6-12 days after the administration of anaphylactogen and reaches its maximum after 3 weeks; proceeds without visible clinical signs. Then the strength of the reaction gradually decreases; however, hypersensitivity can persist for months or even years. When the serum of a sensitized animal is administered to a healthy animal, passive anaphylaxis... With it, the body's reaction occurs after 24-48 hours and lasts 3-4 weeks. Passive anaphylaxis can be passed from mother to fetus through the placenta. With the repeated administration of the same anaphylactogen, an anaphylactic reaction (anaphylactic shock, Arthus phenomenon, etc.) rapidly develops in a sensitized animal. Anaphylactic shock occurs with repeated parenteral administration of the same protein substance in the form of a violent, rapidly occurring reaction, sometimes 2-3 minutes after the administration of anaphylactogen. The clinical picture of anaphylactic shock depends on the type of animal, the route of administration and the dose of antigen and can vary significantly. Acute anaphylactic shock is characterized by pronounced anxiety of the animal, increased respiration and heart rate, decreased blood pressure, the appearance of tonic and clonic seizures, involuntary separation of feces and urine; changes in the morphological and biochemical composition of the blood. The animal may die with symptoms of suffocation due to paralysis of the respiratory center, or quickly returns to a normal state. Autopsy of dead animals from shock reveals hyperemia of internal organs, hemorrhages on the mucous membrane of the gastrointestinal tract, in the liver and kidneys. During histological examination, protein dystrophy and fatty infiltration are noted in them. After anaphylactic shock, the amount of protective antibodies in the body decreases, the serum complement decreases, the phagocytic capacity of macrophages decreases, and the body's susceptibility to infectious diseases increases. Animals that survived after anaphylactic shock become resistant to the introduction of the same substance. A. M. Bezredka called this phenomenon anti-anaphylaxis, or desensitization. It occurs 10-20 minutes after the clinical manifestations of shock and lasts up to 40 days in guinea pigs, and up to 9 days in rabbits. The state of sensitization can be reduced or eliminated if small doses of the same antigen are administered to the animal several hours before the introduction of a permissive dose of antigen. This method, proposed by A. M. Bezredkaya, is used to prevent anaphylactic reactions, in particular serum sickness.

Artyus phenomenon - local anaphylaxis - an inflammatory process that develops in a sensitized animal at the site of repeated administration of anaphylactogen. In this case, there is a general sensitization of the body; if anaphylactogen is administered intravenously to such an animal, anaphylactic shock may occur. There are several theories explaining the mechanism of the formation of A. According to the hypothesis of humoral factors, antibodies are formed during sensitization, which circulate in the blood. When the antigen is administered a second time, it reacts with the antibody; the resulting protein complex is cleaved by proteolytic enzymes, resulting in the formation of intermediate decomposition products, including anaphylotoxin, which determines the picture of an anaphylactic reaction (it was not possible to isolate anaphylotoxin in its pure form). According to other sources, anaphylactic shock occurs as a result of the formation of substances such as histamine in the blood. Some researchers associate the cause of anaphylactic shock with profound changes in the colloidal composition of the blood. Cellularists believe that antibodies react with antigens in cells. When they are combined, the vital activity of cells is disrupted, which leads to anaphylactic shock. A. M. Bezredka was the first to point out the importance of the nervous system in the development of A., proving this by the fact that in A.'s experiment it is possible to prevent the introduction of narcotic drugs. During hibernation in animals, it is also very rare to cause anaphylactic shock. Phenomenon A. should be interpreted as a complex of body reactions in which the central nervous system, endocrine glands, and immune mechanisms participate. Antihistamines, hormones, and ephedrine are used to treat A.

Due to the widespread distribution of food additives, flavors and preservatives, this century can rightfully be called the "era of allergies", since this pathology is found almost everywhere. And not only among people, but also among our smaller brothers. This condition is extremely dangerous. For example, anaphylactic shock in dogs often leads to the death of a pet, since the owners do not always know about those signs, upon the appearance of which the animal must be immediately taken to a veterinary clinic.

This is the name of an extremely serious pathological condition. In fact, this is a strong, generalized allergic reaction that develops as a response to the repeated ingestion of a specific antigen into the body of a sensitive animal. By the way, for the first time, anaphylaxis was studied precisely on the example of dogs. If you disassemble the term, then it consists of two parts: "Ana", that is, "reverse" and "Philax", that means - "protection". That is, the word for this can be translated as "Abnormal, excessive protection." In general, this is the way it is, because anaphylactic shock occurs with an inadequate, excessive response of the body's immune system to some substance that has got into it. For the first time, such a phenomenon was recorded when experimental dogs were injected subcutaneously with an extract from the tentacles of sea anemones.

Main types

Depending on the "leading" lesion, experts identify five variants of anaphylactic shock in dogs at once:

Collapse (hemodynamic variety).

Asphyxial.

Cerebral.

Abdominal.

Thromboembolic.

Causes of anaphylactic shock in dogs

The most significant causes of anaphylaxis in dogs are exposure to animal and insect poisons and drugs. Shock can occur from bites:

bumblebees,
bees,
hornets,
tarantulas,
spiders,
serpent.

Any medications can cause the development of anaphylactic shock, but antibiotics are in the first place (cephalosporins, penicillins, tetracyclines, vancomycin, chloramphenicol, etc.). They are followed by non-steroidal anti-inflammatory drugs, radiopaque agents, general anesthetics, muscle relaxants.

Such a reaction is also possible from the administration of sera, hormones (ACTH, insulin, progesterone and others), enzymes (penicillinase, streptokinase, trypsin, chymotrypsin, asparaginase), vaccines, chemotherapeutic agents (cyclosporine, vincristine, methotrexate, etc.), sodium thiosulfate, local anesthetics.

Development of anaphylactic shock: the first symptoms

No matter what the cause, shock always develops in the same way. The first is the immunological reaction of the dog's body. Anaphylaxis can be local or systemic. Local manifestations are angioedema and urticaria. When urticaria appears:

redness,
rashes and blisters
itching occurs.

With angioedema, edema forms in the subcutaneous tissues and deep layers of the skin. Various gastrointestinal reactions also occur: tenesmus, nausea, vomiting and diarrhea. Sometimes urticaria can progress to systemic anaphylaxis.

Systemic anaphylaxis is the most severe and life-threatening shock. Most often, the liver of the dog suffers with it. The first signs of anaphylaxis are agitation with vomiting. With progression, breathing is impaired, reactions are inhibited, or muscle or cardiovascular collapse develops. Death can occur literally within an hour.

What to do in case of shock in a dog?

When the described symptoms appear after bites or the administration of any drugs, urgent anti-shock measures are necessary. If the cause of shock is a bite or intramuscular or intravenous drug administration, then it is necessary:

apply a venous tourniquet on the limb above the site of antigen intake,
prick this place with 0.1% adrenaline solution,
The sting of an insect during a bite must be removed, ice or a cloth soaked in cold water must be applied to this place and a 0.1% solution of adrenaline must be injected intramuscularly.

To prevent relapse, glucocorticoids (methylprednisolone, prednisolone, dexamethasone) are administered intravenously or intramuscularly. Thus, in order to save the animal in case of anaphylactic shock, the owner of the dog urgently needs to call veterinary assistance or try to deliver the animal to the veterinary clinic. After resuscitation, further treatment is prescribed only by a doctor.

Anaphylaxis is an immediate (first) type of hypersensitivity, one of the types of allergic reactions. Such a reaction is a pathological variant of the immune response to a foreign agent (allergen). The consequence of this reaction is tissue damage in the body.

Under normal conditions, the first time an antigen enters the body, it provokes a reaction from the immune system. She recognizes him, analyzes his structure, which is then memorized by memory cells. In response to the antigen, antibodies are produced, which are stored in the blood plasma in the future. So, the next time an antigen enters the body, antibodies immediately attack and neutralize it, preventing the disease from developing.

Allergy is the same response of the immune system to an antigen with the only difference that with a pathological reaction there is an incommensurable ratio of the strength of the reaction with the cause that provoked it.

There are 5 types of allergic reactions:

I type of - anaphylactic, or immediate allergic reactions. They arise due to the interaction of antibodies of group E (IgE) and G (IgG) with the antigen and the deposition of the formed complexes on the membranes of mast cells. Moreover, as a result of this interaction, a large amount of histamine is released, which has a pronounced physiological effect. The reaction time is from a couple of minutes to several hours after the antigen enters the animal's body. This includes anaphylactic shock, urticaria, allergic rhinitis, atopic bronchial asthma, Quincke's edema.

II type - cytotoxic(or cytolytic) reactions.

III type - immunocomplex reactions(Artyus phenomenon).

IV type - late hypersensitization, or delayed-type allergic reactions that develop 24 hours or more after the antigen enters the body.

V type - stimulating reactions hypersensitivity.

Among the reliably confirmed causes of anaphylaxis in dogs are:

Bites of insects of the family Hymenoptera - four-winged (bees, wasps, hornets, fire ants)
Certain chemotherapy agents, contrast agents, and antibiotics
Blood transfusion

Symptoms

Anaphylaxis most commonly involves the skin, respiratory, cardiovascular, and gastrointestinal systems. Skin and mucous membranes are involved in 80-90% of cases. Most adult patients have some combination of urticaria, erythema, pruritus, and edema — increased porosity of the vascular wall. However, for reasons not yet understood, some dogs are more likely to show respiratory symptoms of anaphylactic shock, accompanied by skin symptoms. It is also important to note that some of the most severe cases of anaphylaxis occur in the absence of cutaneous manifestations. Initially, itching and redness usually occur. Further, for a short time, other symptoms develop:

Dermatological / ocular: lacrimation, urticaria, increased vascular reaction (vessels are sharply injected), itching, hyperthermia and edema.
Respiratory: Nasal congestion, runny nose, rhinorrhea (discharge from the nose), sneezing, shortness of breath, cough, hoarseness.
Cardiovascular reactions: dizziness, weakness, fainting, chest pain, convulsions, tachycardia.
Gastrointestinal: dysphagia, nausea, vomiting, diarrhea, bloating,
Neurologic: headache, dizziness, blurred vision (very rare and often associated with hypotension)

Manifestation of anaphylactic reactions

In dogs, histamine is primarily secreted from the gastrointestinal tract into the portal vein, resulting in hepatic arterial vasodilation and increased hepatic arterial blood flow. In addition, the release of histamine into the portal system creates significant venous outflow obstruction, which results in an increase in vascular wall resistance up to 220% of normal within a few seconds. As a result, venous blood flow to the heart is reduced. A decrease in the venous return of blood from the liver to the heart decreases cardiac output and therefore contributes to hypovolemia and a decrease in oxygen delivery to the tissues. Due to decreased oxygen delivery and hypovolemic shock, common clinical signs include collapse and acute (sometimes hemorrhagic) gastroenteritis.

General principles of therapy for anaphylaxis

Anaphylactic shock in dogs is a medical emergency requiring immediate recognition and intervention. Patient management and prognosis depend on the severity of the initial response and response to treatment. Patients with refractory or very severe anaphylaxis (with cardiovascular and / or severe respiratory symptoms) should be followed up for a longer period of time in an intensive care unit.

Supportive care for patients with suspected anaphylaxis includes the following:

Airway management (eg, ventilation support with a bag or mask, endotracheal intubation, tracheostomy if necessary)
Oxygen therapy with high-flow concentrated oxygen
Cardiac monitoring and / or pulse oximetry
Providing intravenous access (large canal)
Intravenous Stress Bolus Fluid

Drug therapy: initially, in the framework of emergency care for the treatment of acute anaphylactic reactions, adrenaline 0.2-0.5 ml is administered intramuscularly and antihistamines, for example, diphenhydramine 1-4 mg / kg intramuscularly.

Anaphylactic shock is an immediate type of allergic reaction that occurs when an allergen is re-introduced into the body. Anaphylactic shock is characterized by rapidly developing, predominantly general manifestations: a decrease in blood pressure (blood pressure), body temperature, blood clotting, central nervous system disorders, increased vascular permeability and spasm of smooth muscle organs.

Most often, the symptoms of anaphylactic shock occur 3-15 minutes after the body comes into contact with the drug. Sometimes the clinical picture of anaphylactic shock develops suddenly ("on the needle") or several hours later (0.5-2 hours, and sometimes more) after contact with the allergen.

The most typical is the generalized form of drug anaphylactic shock.

This form is characterized by the sudden appearance feelings of anxiety, fear, severe general weakness, widespread itching, skin flushing. The appearance of urticaria, angioedema of Quincke of various localization, including in the larynx region, is possible, which is manifested by hoarseness, up to aphonia, difficulty swallowing, the appearance of stridor breathing. Animals are worried about a pronounced feeling of lack of air, breathing becomes hoarse, wheezing is heard at a distance.

Many animals have nausea, vomit, abdominal pain, cramps, involuntary urination and bowel movements. The pulse in the peripheral arteries is frequent, threadlike (or not detected), the level of blood pressure is reduced (or not detected), objective signs of shortness of breath are revealed. Sometimes, due to pronounced edema of the tracheobronchial tree and total bronchospasm during auscultation, there may be a picture of a "silent lung".

In animals suffering from pathology of cardio-vascular system, the course of drug anaphylactic shock is quite often complicated by cardiogenic pulmonary edema.

Despite the generalization of the clinical manifestations of drug anaphylactic shock, depending on the leading syndrome, five variants are distinguished: hemodynamic (collaptoid), asphyxial, cerebral, abdominal, thromboembolic.

In different animal species, the development of anaphylactic shock is accompanied by various circulatory and respiratory disorders. On the basis of the nature of the disorders of these functions, some researchers (NN Sirotinin, 1934; Doerr, 1922) distinguish several types of anaphylactic shock in animals. Tract of anaphylactic shock in guinea pigs can be called asphytic, since the earliest and leading symptom of anaphylactic shock in these animals is bronchospasm, which causes asphyxia; Against the background of the latter, circulatory disorders of the asphytic type develop for the second time. Blood pressure at first rises sharply in connection with the excitation of the bulbar, vasomotor center with hypercapnia. In the future, paralysis of this center develops, blood pressure drops catastrophically and death occurs. In guinea pigs and rabbits, during anaphylactic shock, excitation of the respiratory center is observed, the motor center radiating to the vessel; in the future, inhibition of these centers occurs, which is expressed in respiratory depression and a drop in blood pressure.

In dogs, anaphylactic shock is a different type; it can be described as collapse-type anaphylactic shock. Hence the name anaphylactic collapse, used by some authors. The leading manifestation of anaphylactic shock in dogs is circulatory disorders in the abdominal organs. Stagnation occurs in the liver, spleen, kidneys and intestinal vessels.

Circulatory disorders in the abdominal organs are a consequence of the effect of the antigen on the nervous mechanisms of regulation of vascular tone in the abdominal organs. The antigen also has a direct effect on the smooth muscles of the hepatic vein wall and some other blood vessels in the abdominal cavity. In many wild animals - bears, wolves, foxes - anaphylactic shock, like in dogs, flows through the mud of the collapse. In rabbits with anaphylactic shock, circulatory disorders in a small circle are the leading ones. There is an increase in blood pressure in the pulmonary artery caused by pulmonary artery spasm.

In rats and mice, anaphylactic shock is characterized by circulatory disorders in the systemic and pulmonary circulation. Anaphylaxis in these species of animals is discussed in a special section.

In cats and in wild animals of the feline order (lions, tigers, leopards, panthers, etc.), anaphylactic shock downstream approaches the type of shock in dogs. However, due to the high excitability of the autonomic nervous system and its parasympathetic division, one of the primary signs of anaphylactic shock in these animals is a sharp slowdown in heart rate up to short-term cardiac arrest.