Anaphylaxis(anaphylaxia from the Greek ana - reverse action + phylaxis - protection, self-defense) - condition hypersensitivity the body to the repeated introduction of a foreign protein (antigen).
Anaphylactic shock (French shoc - blow, push, shock) – general state organism of an animal, caused by the introduction of a permissive dose of antigen and manifested by the development of a generalized immediate-type hypersensitivity reaction, resulting from the accelerated massive release of mediators from mast cells and basophils. All organisms that have an immune system capable of storing in their memory the information of a single encounter with a foreign peptide agent are susceptible to the development of anaphylactic shock.
Causes
There are many reasons that provoke anaphylactic shock in animals. The most significant of them include the effects on the body of various medicines and poisons of animals and insects.
Any medications, regardless of route of administration (parenteral, inhalation, oral, cutaneous, rectal, etc.) can cause the development of anaphylactic shock. In first place among the drugs that initiate anaphylaxis are antibiotics (penicillins, cephalosporins, tetracyclines, chloramphenicol, vancomycin, etc.). Next, in descending order of incidence of anaphylaxis, are nonsteroidal anti-inflammatory drugs (mainly pyrazolone derivatives), general anesthetics, radiocontrast agents, and muscle relaxants. The literature contains data on cases of the development of anaphylaxis with the administration of hormones (insulin, ACTH, progesterone and others), enzymes (streptokinase, penicillinase, chymotrypsin, trypsin, asparaginase), serums (for example, anti-tetanus), vaccines (anti-tetanus, anti-rabies, etc.) , chemotherapeutic agents (vincristine, cyclosporine, methotrexate, etc.), local anesthetics, sodium thiosulfate.
Anaphylactic shock in dogs and cats can develop as a result of animal bites from hymenoptera (bees, bumblebees, hornets, wasps), arthropods (spiders, tarantulas), and snakes. The reason for this is the presence in their venom of various enzymes (phospholipase A1, A2, hyaluronidase, acid phosphatase, etc.), as well as peptides (melittin, apamin, peptides that cause degranulation of mast cells) and biogenic amines (histamine, bradykinin, etc. ).
Development mechanism
However, regardless of the factors that influence the occurrence of anaphylactic shock, the classical mechanism of its development appears to be a cascade of successive stages:
immunological reactions → pathochemical reactions → pathophysiological changes
The first stage in the development of anaphylactic shock is the body's immunological reactions. Initially, primary contact of the body with the antigen occurs, in other words, its sensitization. At the same time, the body begins to produce specific antibodies (IgE, less often IgG), which contain high-affinity receptors for the Fc fragment of antibodies and are fixed on mast cells and basophils. A state of immediate hypersensitivity develops after 7-14 days and persists for many months, or even several years. No more pathophysiological changes occur in the body. Since anaphylaxis is immunologically specific, shock is caused only by the antigen to which sensitization has been established, even when received in negligible quantities.
Re-entry of the antigen (allowing the entry of the antigen) into the body leads to its binding to two antibody molecules, which entails the release of primary (histamine, chemoattractants, chymase, tryptase, heparin, etc.) and secondary (cysteine leukotrienes, prostaglandins, thromboxane, factor activation of platelets, etc.) mediators from mast cells and basophils. The so-called “pathochemical” stage of anaphylactic shock occurs.
The pathophysiological stage of anaphylactic shock is characterized by the effect of released mediators (histamine, serotonin) on vascular, muscle and secretory cells due to the presence of special receptors on their surface - G1 and G2. Attack by the above mediators of “shock organs”, which in mice and rats are the intestines and blood vessels; in rabbits - pulmonary arteries; in dogs – intestines and hepatic veins, causes a fall vascular tone, decreased coronary blood flow and increased heart rate, decreased contraction of smooth muscles of the bronchi, intestines, and uterus, increased vascular permeability, redistribution of blood and impaired coagulation.
Clinical picture
The clinical picture of typical anaphylactic shock in cats and dogs is very clear. It can be divided into three stages - the stage of harbingers, the stage of height and the stage of recovery from shock. In the case of a high degree of sensitization of the body during the fulminant development of anaphylactic shock, the precursor stage may be absent. It should be noted that the severity of anaphylactic shock will be determined by the characteristics of the first two stages - the precursor and peak stages.
The development of the precursor stage occurs within 3-30 minutes after parenteral entry into the body of the resolving antigen or within 2 hours after its oral penetration or release from deposited antigens. injectable drugs. At the same time, individuals involved in the development of anaphylactic shock experience internal discomfort, anxiety, chills, weakness, blurred vision, weakened tactile sensitivity of the skin of the face and limbs, pain in the lower back and abdomen. There is often an appearance skin itching, difficulty breathing, urticaria and the development of Quincke's edema. The stage of precursors is replaced by the stage of the height of the development of anaphylactic shock. During this period, patients experience loss of consciousness, falling blood pressure, tachycardia, cyanosis of the mucous membranes, shortness of breath, involuntary urination and defecation.
The completion of the development of anaphylactic shock is the stage of the individual emerging from shock with compensation of the body over the next 3-4 weeks. However, during this period, patients may develop acute heart attack myocardium, disorder cerebral circulation, allergic myocarditis, glomerulonephritis, hepatitis, meningoencephalitis, arachnoiditis, polyneuritis, serum sickness, urticaria, Quincke's edema, hemolytic anemia and thrombocytopenia.
Depending on which vascular, muscle and secretory cells of which “shock organs” were more exposed to the released mediators, the symptoms of anaphylactic shock will depend. It is conventionally accepted to distinguish hemodynamic, asphyxial, abdominal and cerebral variants of the course of anaphylactic shock.
With hemodynamic variant hypotension, arrhythmias and other vegetative-vascular changes predominate.
With asphyxial variant the main one is the development of shortness of breath, broncho- and laryngospasm.
In the abdominal version spasms of intestinal smooth muscles, epigastric pain, symptoms of peritoneal irritation, and involuntary defecation are noted.
With cerebral variant the dominant manifestation is psychomotor agitation, cramps and meningeal symptoms.
Diagnostics
Diagnosis of anaphylactic shock is not difficult and usually relies on the characteristic pronounced clinical picture diseases observed after an individual has been bitten by stinging hymenoptera insects, poisonous arthropods, animals, as well as during the administration of medications.
Treatment
The principles of treatment of anaphylactic shock provide for the mandatory implementation of anti-shock measures, intensive care and therapy in the stage of the individual coming out of shock.
Algorithm therapeutic measures within the framework of providing emergency assistance appears as follows. In the event of a bite from poisonous animals, insects, or ingestion of allergenic medications for an individual, a venous tourniquet must be applied to the limb above the site of entry of the antigen and the area injected with a 0.1% solution of adrenaline. If there is an insect sting in soft tissues remove the latter and put ice on this place, and then inject a 0.1% solution of adrenaline intramuscularly. If necessary (at the discretion of the attending physician), repeat the injection of a 0.1% adrenaline solution after 5 minutes. In order to prevent relapse of anaphylactic shock, administer glucocorticoids (prednisolone, methylprednisolone, dexamethasone) intravenously or intramuscularly. They can be administered again after 4-6 hours.
To reduce negative consequences In case of anaphylactic shock, intravenous or intramuscular injection of antihistamines is recommended, the administration of which helps to level out skin manifestations of allergies.
In the asphyxial variant of anaphylactic shock, when bronchospasm and/or laryngospasm develops, in addition to the above medications, drugs that improve pulmonary ventilation are prescribed, for example, euphilin in combination with oxygen therapy. In more severe cases or if the therapy provided is ineffective, tracheostomy is resorted to.
Activities in the stage of an individual recovering from shock include continuing assistance according to the algorithm described above, intensive therapy with rehydration of the body by administering saline, glucose solution, etc. intravenously quickly over 5 minutes, and then intravenously slowly using a drip.
Forecast
The prognosis for anaphylactic shock is cautious. This is explained by this pathology is caused by immunocompetent memory cells that live in the individual’s body for months and years. In this regard, in the absence of desensitization of the body, there is a constant probability of developing anaphylactic shock. This is confirmed by the results of L. Dowd and B. Zweiman, who indicated that in patients, symptoms of anaphylaxis can recur after 1–8 hours (biphasic anaphylaxis) or persist for 24–48 hours (protracted anaphylaxis) after the appearance of its first signs.
Prevention
In terms of preventing anaphylactic shock, there are three directions. The first direction involves excluding the individual’s contact with the permitting agent. The second direction is based on testing the tolerance of drugs to animals before providing medical care. For this purpose, 2-3 drops of the solution intended for use are applied to the animal in the sublingual space or it is injected intravenously in a volume of 0.1-0.2 ml, followed by observation for 30 and 2-3 minutes, respectively. The appearance of swelling of the mucous membrane, itching, urticaria, etc. indicates sensitization of the body and, as a consequence, the impossibility of using the test drug.
Veterinary center"DobroVet"
Anaphylaxis is an immediate (first) type of hypersensitivity, one of the types of allergic reactions. This 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.
IN normal conditions When an antigen first enters the body, it provokes a reaction from immune system. She recognizes it, analyzes its structure, which is then memorized by memory cells. In response to the antigen, antibodies are produced, which remain 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.
An allergy is the same response of the immune system to an antigen, with the only difference that in a pathological reaction there is a disproportionate ratio of the strength of the reaction to the cause that provoked it.
There are 5 types of allergic reactions:
I type – 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 sedimentation of the resulting complexes on the membranes of mast cells. As a result of this interaction, a large amount of histamine is released, which has a pronounced physiological effect. The time for the reaction to occur ranges from a couple of minutes to several hours after the antigen enters the animal’s body. These include anaphylactic shock, urticaria, allergic rhinitis, atopic bronchial asthma, Quincke's edema.
Type II – cytotoxic(or cytolytic) reactions.
III type – immune complex reactions(Arthus 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:
- Insect bites of the family Hymenoptera - four-winged (bees, wasps, hornets, fire ants)
- Some chemotherapy agents, contrast agents, and antibiotics
- Blood transfusion
Symptoms
In anaphylaxis, the skin, respiratory, cardiovascular and gastrointestinal systems are most often involved. The skin and mucous membranes are involved in 80-90% of cases. Most adult patients have some combination of urticaria, erythema, itching, and edema—increased porosity of the vessel wall. However, for reasons that are still poorly understood, some dogs are more likely to exhibit 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 skin manifestations. Initially, as a rule, itching and redness occur. Then, over a short period of 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 (nasal discharge), sneezing, shortness of breath, cough, hoarseness.
- Cardiovascular reactions: dizziness, weakness, fainting, chest pain, convulsions, tachycardia.
- Gastrointestinal tract: dysphagia, nausea, vomiting, diarrhea, bloating,
- Neurological: headache, dizziness, blurred vision, (very rare and often associated with hypotension)
Manifestation of anaphylactic reactions
In dogs, histamine is primarily released from gastrointestinal tract V portal vein, which leads to 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 leads to increased resistance vascular wall up to 220% of normal within a few seconds. As a result, venous blood flow to the heart is reduced. Decreased venous return of blood from the liver to the heart reduces cardiac output and therefore contributes to hypovolemia and decreased oxygen delivery to tissues. Due to decreased oxygen delivery and hypovolemic shock, common Clinical signs include collapse and acute occurrence gastroenteritis (sometimes hemorrhagic in nature).
General principles of anaphylaxis treatment
Anaphylactic shock in dogs is emergency, requiring immediate recognition and intervention. Patient management and prognosis depend on the severity of the initial reaction and response to treatment. Patients with refractory or very severe anaphylaxis (with cardiovascular and/or severe respiratory symptoms) should be observed for more than long period time in the intensive care unit.
Supportive care for patients with suspected anaphylaxis includes the following:
- Airway management (eg, bag or mask ventilation support, endotracheal intubation, tracheostomy if necessary)
- Oxygen therapy with high-flow concentrated oxygen
- Cardiac monitoring and/or pulse oximetry
- Providing intravenous access (large channel)
- Intravenous stress bolus fluid administration
Drug therapy: Initially, as part of emergency care for the treatment of acute anaphylactic reactions, adrenaline 0.2-0.5 ml intramuscularly and antihistamines, for example, diphenhydramine 1-4 mg/kg intramuscularly, are administered.
intensive care veterinarian at MEDVET
© 2018 SEC "MEDVET"
Due to the widespread food additives, flavorings and preservatives, the current century can rightfully be called the “era of allergies,” since this pathology occurs 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 the pet, since owners are not always aware of the signs that, when they appear, should be immediately taken to a veterinary clinic.
This is what is called extremely heavy pathological condition. Essentially, it is a strong, generalized allergic reaction, developing as a response to the repeated entry into the body of a sensitive animal of a certain antigen. By the way, anaphylaxis was first studied using dogs as an example. If you look at the term, it consists of two parts: “Ana”, that is, “reverse” and “Philax”, which means “protection”. That is, the word for this can be translated as “Abnormal, excessive protection.” In general, this is so, because anaphylactic shock occurs when the body’s immune system has an inadequate, excessive response to some substance that has entered it. This phenomenon was first 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:
- Collapse (hemodynamic type).
- Asphyxial.
- Cerebral.
- Abdominal.
- Thromboembolic.
Read also: Encephalitis tick in dogs
Hemodynamic shock is characterized by a sharp change in the volume of circulating blood (the appearance of collapse), as well as other phenomena that are caused by circulatory disorders in the pulmonary circulation (including pulmonary edema). However, the latter is more typical for the asphyxic variety, when spasms of the respiratory tract are especially pronounced. The most uncharacteristic is the cerebral variant, when the dog has serious mental disorders. She becomes unusually active, running in circles without stopping or showing signs of fatigue (classic symptoms of brain damage). As a rule, everything ends with subsequent death from deep functional disorders in the cerebral cortex. In a milder version, the dog shows signs of severe fear, sweats, whines and hides in the most remote and dark corners.
The signs of the abdominal form are at first very similar to the symptoms of the aggravated form: the dog whines due to severe pain, does not allow one to palpate the abdomen, visible mucous membranes turn pale and become cold. Happens often
Anaphylactic shock is a condition of the animal's body, the cause of which is the received dose of antigen.
Causes of the disease
There are several causes of anaphylaxis in dogs.
- Insect bites. Ingestion of poisons into a dog's body is the most common cause of anaphylactic shock. Anaphylaxis can result from a bee, bumblebee, wasp, tarantula, snake or spider sting.
- Medicines. Can cause anaphylactic shock medications. The most common pathogens are antibiotics, general anesthetics, anti-inflammatory drugs non-steroidal drugs, muscle relaxants, radiocontrast agents.
- Hormones and serums. Anaphylactic shock can be caused by the administration of drugs such as insulin, ACTH, progesterone and others.
- Enzymes. Anaphylactic shock can occur with artificial administration of streptokinase, trypsin, asparaginase, and chymotrypsin.
- Vaccines and chemotherapy drugs. Anaphylaxis can be caused by drugs such as vincristine, methotrexate and cyclosporine.
Symptoms of the disease
Regardless of the cause, the symptoms of shock are the same. The first signs of anaphylaxis are:
- Skin irritation - redness, blisters, rash.
- Anginoneurotic edema - swelling of the deep layers of the skin and subcutaneous tissues.
- Nausea, vomiting, possible diarrhea.
Systemic anaphylaxis is the most dangerous form a disease that affects the dog's liver. The first signs of this disease are respiratory failure, vomiting, decreased reaction, and possible development of cardiovascular or muscle collapse.
Treatment of the disease
If symptoms of the disease appear, the dog owner must take immediate anti-shock measures. If shock occurs due to a bite or medication, the following steps must be taken.
- Apply a tourniquet (venous) to the injured limb, which should be located above the point of entry of the poison or medicine.
- Inject the site where the antigen was received with a 0.1% adrenaline solution.
- It is necessary to remove the sting received from the bite, apply ice or a cloth previously soaked in cool water.
- Inject adrenaline solution intramuscularly.
If an animal experiences anaphylactic shock, you must immediately contact a veterinarian - call a doctor at home or take your pet to a veterinary hospital yourself. After the animal has received resuscitation, treatment should only be prescribed by a veterinarian.
Doctors call anaphylaxis a severe allergic reaction, in some cases leading to fatal outcome. Most often it is caused by the ingestion of some substances into the body that cause rejection. Sometimes they can penetrate through food, sometimes through scratches or injections. Delay in taking help can lead to anaphylactic shock, respiratory failure and heart failure. The result of inaction is death. However, it is possible to provide assistance.
What substances can cause anaphylaxis in dogs?
In fact, there are a lot of options, but there are the most common ones. Here is an approximate list of them:
- Vaccines and drugs
- Food products
- Certain hormones and antibiotics
- Insect bites
Symptoms of Anaphylaxis in Dogs
Signs of anaphylaxis can be very unpleasant:
- State of shock
- Convulsions
- Diarrhea
- Gums turn pale and limbs become cold
- Vomit
- The heartbeat becomes more intense, but the pulse weakens
One of the main distinctive features- swelling in the facial area.
Helping a dog with anaphylaxis
In view of higher level The danger of this disease requires special efficiency from the owners. Contact your veterinarian as soon as possible. You will need to administer adrenaline (epinephrine), and urgently. A few minutes of delay can cost your life. Sometimes the veterinarian may administer medications (fluid/oxygen) intravenously, depending on the situation.
Is it possible to prevent anaphylaxis in dogs?
Unfortunately, it is almost impossible to predict the allergenic substance. And if anaphylaxis, rash or angioedema has already occurred in a dog, all that remains is to be observant and notice what substances caused these phenomena. It is especially important to cooperate with a veterinarian regarding the use of drugs and vaccines that caused allergies in the dog. Information about this should be included in her treatment record.
A dog may experience discomfort during vaccination. And if, in addition, an allergic reaction is observed, then a specialist needs to take the situation under increased control. If your dog needs to be vaccinated, it should be administered before antihistamine. And only then, after the vaccine is administered, you can observe the reaction for about 20-30 minutes. In some cases, you can replace certain vaccines with others.
Do you know that…
Vaccines sometimes contain antibiotics as preservatives. And if your dog is allergic to any antibiotics, it is worth checking the vaccines for their presence. If you do this in advance, before use, you can avoid problems.
Situation. Your pet is not suffering from food and medicine, but is too sensitive to insect bites. What to do?
1. First of all, before a critical problem arises due to the bite, consultation with a veterinarian will be required. He will tell you options operational assistance in case of development of Quincke's edema or acute form anaphylactic reaction.
2. You may be advised to have a disposable syringe with a dose of adrenaline. If a reaction begins to develop, you can use it as first aid before the veterinarian arrives. Since it is sold by prescription only, you cannot buy it without a doctor's recommendation.
It is especially important to have a plan emergency care during a trip when prompt veterinary intervention is not possible. It is also impossible to completely protect your pet from bites.
NOTE! An anaphylactic reaction sometimes occurs not after the first, but after repeated administration of the vaccine. Therefore, if everything went well the first time, this does not mean that there will be no allergies. Even after 3, 5 or 10 injections of the vaccine, an anaphylactic reaction may appear for the first time.
The intensity of the anaphylactic reaction does not depend on how old the animal is. However, the dog's general predisposition to allergies should prompt owners to special attention treat possible manifestations anaphylaxis. If skin rashes or swelling have already appeared, an anaphylactic reaction to medications can occur at any time.
