What Are the Symptoms of a Dog Bitten by a Spider?

Spider bites, in most cases, look just like a bug bite or bee sting. They have little or no effect on your pet's health beyond a raised red welt on the skin, which may be accompanied by itching or light swelling. However, there are a few exceptions. In the United States, brown recluse, black widow and hobo spiders all inject venom into a bite victim. The venom may cause serious medical complications requiring the attention of a veterinarian. It is important for dog owners to know the symptoms of these bites in order to protect their pet.

  1. Brown Recluse

    • This bite will look much like a benign spider bite shortly after the bite occurs. A welt will rise in the middle of a reddened area that may feel warm to the touch. Dogs may find the area surrounding a bite tender. Some dogs will, in the hours following the bite, develop a secondary set of symptoms that include fever, chills and a spreading rash.

      The bite of the brown recluse spider, over time, causes damage to the skin and muscular tissue that surrounds the bite. The resulting deterioration will look like a sore with a dark scab inside a white center, surrounded by a spreading red ring. When the scab falls off, an ulcer, or hole, is left beneath it. This ulcer will take several weeks to heal, and must be guarded from secondary infection.

    Black Widow

    • The bite of the black widow, injects a neurotoxin into the system of your pet that will, initially, only cause pain at the site of the bite. Over time, this pain spreads into the surrounding tissue, invading the nearest lymph nodes. This pain will continue to intensify for up to three hours, and will likely persist for up to two days, according to PetsMD.

      After a time period of 10 to 20 hours, the neurotoxins will begin to affect the activity level of your pet. The degree to which you pet is affected and the threat posed to their long-term health, greatly depend on the size of the animal, the animal's health before the bite and the location in which they were bitten. Generally, these more serious symptoms are first demonstrated in a marked decrease in your dog's routine movement, as they begin to experience paralysis. This paralysis may be demonstrated in a muscular rigidity especially in the abdominal area, a general weakness in the limbs or a total inability to move. Other serious symptoms that occur as a result of the damage being done to the nervous system include seizure, a racing or irregular heart rate, and breathing irregularities.

    Hobo Spiders

    • About half of hobo spider bites are dry, which means they do not inject any venom, according to HoboSpiders.com. Dogs that experience a dry bite may suffer some skin irritation at the site of the bite, but no further symptoms. If a dog is bitten, and venom injected, the symptoms are identical to those created by the brown recluse.