Black Widow Spider Bites in Cats

Bearing in mind that not all widow spider bites contain venom, as spiders can control the amount released, this substance is one of the most deadly toxins by volume in the world.

Black widow spider bites must be treated as an emergency as cats are highly sensitive to the venom, and one single bite can lead to the animal's death if not promptly treated.

Symptoms may begin to occur within minutes after envenomation; in most cases, severe symptoms start to develop within eight hours of the bite.The venom contains a number of different components, including the potent neurotoxin α-latrotoxin.

Following a widow spider bite, the venom is taken up by the lymphatics and then enters the bloodstream, causing severe paralysis.

Black widow spider bite poisoning, also known as latrodectism, is caused by the venom injected via the bite of a black widow spider. While black widow venom is among the most deadly toxins by volume in the world, and a single bite can cause a cat's death, not all bites contain venom, as black widow spiders can choose how much venom to inject, if any (dry bite).

A number of different widow spiders can be found throughout the United States; they include:

• Black widow spider (Latrodectus mactans): commonly found in the southern United States.
• Western black widow spider (Latrodectus hesperus): western United States.
• Northern black widow spider (Latrodectus variolus): found throughout the northern United States. The hourglass mark is not joined.
• Red widow spider (Latrodectus bishopi): found in central and southern Florida.
• Brown widow spider (Latrodectus geometricus): mainly found in Florida.

Envenomation is usually not witnessed, and diagnosis is based on clinical presentation. There is no specific diagnostic test to definitively confirm envenomation.

A cat presenting symptoms of black widow spider poisoning generally undergoes the following diagnostics:

• Physical examination
• Complete blood count
• Serum analysis
• Urinalysis

Treatment focuses on supportive and symptomatic care; options involve:

• Pain medication (opioids and benzodiazepines)
• IV fluid therapy
• Topical cleaning of the bite wound
• Muscle relaxants
• Supplemental oxygen
• While antivenom (Lyovac) is available, it is rarely prescribed and is only indicated in severe cases as it can potentially cause severe allergic reactions.

Once the animal is treated, weekly monitoring is required.

Prognosis varies from very good to extremely poor and is dependent on the amount of venom injected (dry bites are possible and do not cause any symptoms) and the promptness of treatment. A single bite can be fatal. If the amount of venom injected is large enough and the animal does not receive prompt treatment, most cases end in fatality.

Prognosis for an animal bitten multiple times is extremely poor.

Cats are highly susceptible to black widow spider bites and may die rapidly after envenomation; as such, prevention is of the utmost importance. Black widow spider bite positing is not contagious, but humans are as likely to be bitten, and therefore prevention strategies apply to both pets and humans. Prevention strategies include:

• Shaking bedding, clothes, towels, and other materials before use
• Not letting let pets or children wander in potentially spider-infested spaces (e.g., sheds)
• Trimming high grass

Black widow spiders can be found world wide but are more likely to live in tropical and temperate regions.

• Pain medication
• IV fluid therapy
• Topical cleaning of the bite wound
• Muscle relaxants
• Antivenom