Hornets Poisoning in Dogs

Some of the insects of the Hymenoptera family employ a venom to disable their prey and defend their territory. Insects in this category would include bees, wasps and fire ants. Hornets are a large and aggressive subset of wasp that builds its paper-like nest high in trees. They have a thin waist like other wasps but they are generally much larger and have a more rounded abdomen than other wasps. The venom from a single hornet sting generally will not harm your dog, but it can become a life-threatening situation if your pet is stung numerous times or has an allergic reaction to the sting.

A hornet is an aggressive subset of wasp that normally poses little threat. Some dogs are allergic to the hornet’s venom and can have an acute response.

In most cases a single sting from a hornet or other flying venomous insects of the order Hymenoptera is not life threatening. In rare cases, your dog may have an allergic reaction known as anaphylactic shock. 

Signs of anaphylactic shock:

• Changes in behavior
• Cold limbs
• Collapse
• Death
• Diarrhea
• Drooling
• Elevated heart rate
• Hives
• Inappropriate soiling 
• Itchiness
• Lethargy
• Pale gums or mucous membranes
• Shallow and rapid breathing
• Swollen muzzle or tongue
• Urination
• Vomiting
• Weak pulse 
• Weakness

If symptoms of anaphylactic shock do not occur within 30 minutes, they are unlikely to occur. 

Types 

Stings from hornets, which are a subset of wasps, can differ significantly from bee stings in composition even though the results appear to be the same. Both venoms will trigger the release of histamine, but they do it by targeting different systems. 

The venom in a bee sting acts as an anticoagulant and causes localized inflammation. This venom is more acidic and bicarbonate of soda placed on the sting may help ease symptoms.

The venom in a wasp sting attacks the nervous system on the cellular level by breaking down the cell membrane surrounding the nerve cells and causing pain. Other chemicals in the venom slow the flow of blood to maximize the pain deterrent. The venom in wasp stings is alkaline rather than acidic and is better managed with a mild acid such as diluted vinegar or lemon juice.

Allergic response caused by sensitivity

In this case, the patient has a specific allergy to the venom of the hornet. Dogs who are allergic to bees may or may not be allergic to wasps and hornets as the venom between the two is chemically very different.

What to do: 

Remove the stinger by scraping it off using something flat and rigid, like a credit card. Do not squeeze the stinger as this can inject more venom under the skin. Contact your veterinarian immediately. This is a life-threatening situation and your veterinarian may recommend that you administer an over the counter antihistamine before leaving for their office. If you have an epi-pen for your pet, use it as directed to counteract the allergic reaction.

Toxic response caused by swarming

The stings of all of the venomous Hymenoptera are mildly toxic. When their nesting area is disturbed this can cause them to swarm and attack all at once. This behavior is triggered by pheromones released from the insect’s body, so crushing a hornet or other wasp near its nest also has the potential to trigger a group attack. When this happens, the amount of toxin can be overwhelming to the body.

What to do:

If you are near a hornets’ nest but they are not acting aggressively, move away quickly and calmly. Fast movements may trigger an attack response. If you and your pet get caught in a swarm, your first priority is to get away. Cover as much of you and your pet’s skin as you can and run until the swarm subsides or you can find a safe place to shelter. Do not swat at the hornets or flail your arms as this is likely to encourage them. Once you have gotten away from the attack, remove any stingers from your pet and yourself and call for medical or veterinary assistance for anyone stung more than 15 times, or anyone showing signs of a reaction to the venom.

In many cases, you may not see the actual stinging incident, and your pet may start to exhibit symptoms of an anaphylactic response. Almost all cases of anaphylactic shock are diagnosed based on the physical examination and history of the animal. Treatment of anaphylactic shock must start immediately for any animal experiencing an anaphylactic episode as death can occur within less than one hour from exposure to the allergen. Once your companion is stabilized, the veterinarian will most likely want to get a complete blood count, blood chemistry, and urinalysis to rule out any underlying or concurrent conditions. If an anaphylactic response is the only thing causing a problem for your pet these tests should be unremarkable. If the patient is having trouble breathing due to the allergic reaction a tube may need to be inserted into the throat temporarily in order to provide air until the swelling goes down. X-rays of the chest may be recommended to assess pulmonary function.

Treatment of a simple sting can usually be managed at home by removing the stinger and applying a cold compress to the area of the sting. Mild allergic responses may trigger some swelling and itching. If you were able to observe if your pet was stung by an actual hornet or wasp you could apply a diluted vinegar or lemon solution to the sting to reduce swelling and itching and over the counter antihistamines such as Benadryl may be recommended by your veterinarian. It is important to contact your veterinarian for dosing and contraindications before administering any antihistamines.

If the canine that was stung goes into anaphylactic shock it can become fatal if the airway becomes constricted. Severe allergic reactions will be treated with antihistamines and epinephrine administered intravenously in order to aggressively suppress the body’s histamine response. In some cases, vasopressors may also be used to constrict the blood vessels and increase blood pressure. Inhaled albuterol may be given by nebulizers in situations in which other treatments are failing to provide adequate relief.

If your dog experienced an allergic response to a hornet, then they are more likely to develop an anaphylactic response if stung again in the future. This applies even if the initial allergic response was not anaphylactic in nature. It is generally recommended that you carry a wasp sting kit with you if your pet has reacted to any sort of Hymenoptera sting. The wasp sting kit includes an Epi-Pen to use in the event that your pet is affected by a severe allergic response in the future. It is very important that you learn how to properly administer this medication in the event of an emergency.