Symptoms and Signs of Anaphylactic Shock in Dogs

Source: PetWave, Updated on July 16, 2015
Anaphylactic Shock

How Anaphylactic Shock Affects Dogs

For most people, the phrase “anaphylactic shock” conjures up images of a life-threatening allergic reaction to a bee sting or some other trigger that causes rapid throat and bronchial constriction. Anaphylaxsis manifests somewhat differently in dogs than it does in people, but it still is a potentially fatal medical emergency. Anaphylactic reactions in people typically affect the throat, trachea and upper airways, because the reaction normally starts in the lungs. In dogs, anaphylaxis primarily targets the cardiovascular system and the gastrointestinal system, with respiratory signs developing secondarily. Symptoms develop almost immediately (usually within minutes) after exposure to the causative allergen. The dog’s immune system mounts an aggressive but inappropriate response to whatever the dog is allergic to, releasing “inflammatory mediators” into the blood stream which in turn trigger a number of other events. The dog’s arteries and veins become stretched beyond their normal dimensions and become increasingly leaky, causing blood pressure to drop dangerously. Mucous and other secretions build up in the lungs and throat, causing respiratory distress, and the heart muscle starts pumping irregularly, in abnormal and random rhythms. In addition, affected dogs may develop severe itchiness (called pruritis) and experience extreme pain.

Symptoms of Anaphylaxis

Anaphylactic reactions occur almost immediately – usually within moments after a dog touches, inhales, ingests or otherwise is exposed to the inciting allergen. The first signs of anaphylactic shock in dogs usually include very rapid onset of one or more of the following:

  • Diarrhea
  • Defecation
  • Urination
  • Vomiting
  • Itchiness (pruritis)
  • Development of hives (urticaria)

These symptoms quickly progress to one or more of the following:

  • Weakness
  • Lethargy
  • Drooling (hypersalivation)
  • Shallow, rapid and difficult breathing (respiratory distress; dyspnea)
  • Pale gums and other mucous membranes
  • Elevated heart rate (tachycardia)
  • Weak pulses
  • Cold limbs
  • Changes in mental clarity (excitement or depression)

Left untreated, the end result of anaphylactic shock almost always is seizures, collapse, coma and death. Dogs suffering anaphylactic episodes normally do not have severe or obvious swelling around their throat or face, unless the allergen came into contact with the dog in that area. Dogs having hypersensitivity reactions to allergens such as bee stings, vaccines or other pharmaceutical injections may develop mild to moderate swelling or bruising around the entry site. If any or even some of these signs appear suddenly in your dog, take him or her to a veterinarian right away. Anaphylactic shock is almost always fatal if not treated immediately.

Dogs At Increased Risk

There do not appear to be any age or gender predispositions to developing anaphylactic shock. Boxers and Pit Bull Terriers are most commonly affected with urticaria – a vascular skin reaction marked by the development of raised red patches on the skin (called wheals) and intense itchiness (called pruritis). Another term for this condition is “hives.” Dogs that spend a great deal of time outdoors during the warmer spring and summer months are at an increased risk for insect or snake-bite related anaphylactic reactions.

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