Pet Spider Health

People usually end up searching for pet spider health advice for one of three reasons: a spider has stopped eating, the enclosure “doesn’t feel right” (too dry, too wet, too hot), or something unfamiliar has appeared on the body or around the mouthparts. With spiders, small husbandry slips can quietly build into bigger problems, especially around moulting, dehydration and pests.

The safest approach is simple and steady: match the enclosure to the species, keep conditions stable, watch for a short list of meaningful changes, and know when a vet is the next step. This guide focuses on practical checks and common issues seen in pet spiders in Australia, without guesswork.

First, a quiet truth about “normal” spider behaviour

A healthy spider can look inactive for long stretches. Many species spend most of their time tucked into a retreat, moving mainly at night, and responding strongly only to prey vibrations or disturbance. That stillness can be normal, especially in larger theraphosid spiders (tarantulas).¹

What matters is the pattern over time: posture, body condition, ease of movement, consistency of feeding, and whether the enclosure conditions make sense for the species.

Common health issues in pet spiders

Mites and other pests

Mites can hitchhike in on feeder insects, decor, substrate, or newly acquired animals. A few may be seen as tiny moving dots; heavier loads can cluster around joints, the mouthparts, or soft areas and may coincide with lethargy or poor feeding.

If you suspect mites:

• Isolate the spider from other invertebrates.
• Remove uneaten prey promptly and improve enclosure hygiene.
• Avoid home “chemical treatments” inside the enclosure; residues can harm spiders.
• Seek an exotics-competent veterinarian for species-appropriate advice and treatment options.

Dehydration (often from dry air, poor access to water, or an overly ventilated setup)

Dehydration is one of the most common captive problems, and it’s often misunderstood. Many spiders do best with a reliable water source and the right substrate moisture for their natural habitat, rather than frequent misting. Many species can be supported with a shallow water dish and sensible moisture management that doesn’t turn the enclosure stagnant.^{2, 3}

Signs that can fit dehydration include a dull or “drawn” look to the abdomen, reduced responsiveness, unsteady movement, and repeated refusal of prey in a spider that would usually feed. These signs can overlap with pre-moult behaviour, so look at the whole picture (see “Moulting” below).

Bad moults and moulting complications

Moulting is a vulnerable time. A spider may stop eating for days to weeks beforehand, become less active, and spend more time in its retreat. Problems are more likely when the enclosure is too dry for that species, when the spider is dehydrated, or when it’s disturbed mid-process.

Hands-off is usually best. If a moult is clearly stuck or the spider cannot free limbs, contact a vet promptly (and avoid pulling shed skin yourself).

Injuries (especially falls)

Terrestrial spiders can rupture the abdomen after a fall. This risk increases with tall enclosures, sparse furnishings, or hard decor. Keep climb height sensible for ground-dwellers and provide stable hides and “soft landing” substrate.²

Signs your spider may be unwell (and not just resting)

Spiders don’t advertise illness. Changes are often quiet, then suddenly obvious. Pay attention to these:

• Posture changes: persistent “curling” of the legs under the body can signal severe stress or dehydration.
• Repeated failure to right itself, wobbliness, or unusual weakness.
• Abdominal changes: very shrunken abdomen, obvious injury, leaking fluid, or rapid loss of condition.
• Unusual growths or residues: persistent white fuzz (possible mould), crusting around mouthparts, or heavy mite presence.
• Sudden environmental mismatch: overheating, direct sun on the enclosure, or a dried-out setup for a species that needs moisture.³

If you’re unsure, record what you’re seeing (photos, dates, feeding history, temperature/humidity readings if you use gauges). That history helps a vet far more than a single snapshot.

Enclosure basics: getting the environment right

Spider health is mostly environmental. Different species need different temperature, humidity, substrate and ventilation, and the safest general rule is to mimic the animal’s natural conditions while keeping the enclosure secure and well-aired.³

Security and ventilation

Spiders can slip through small gaps. Use an enclosure that seals properly while still allowing airflow. Position it somewhere stable: out of direct sun, away from heaters and draughts.³

Temperature and humidity: avoid extremes

There isn’t one “correct” humidity number for all pet spiders. Many keepers succeed by aiming for species-appropriate ranges and focusing on steady, breathable conditions: a water dish, correct substrate moisture, and cross-ventilation rather than constantly wet walls.²

Use the spider’s behaviour as feedback. A spider that hugs the water dish, stays unusually exposed, or repeatedly seeks the dampest corner may be telling you the enclosure is too dry. A musty smell, visible mould, or persistently wet substrate suggests the opposite problem.

Substrate, hides and layout

Provide substrate depth and structure that suits the species (burrowing species need depth; arboreal species need vertical anchors). Add a secure hide. Keep decor stable and avoid sharp, heavy objects that could pin or injure a spider.

Nutrition and feeding (what to offer, and what to avoid)

Most commonly kept pet spiders are predators that do well on appropriately sized live invertebrate prey (for example crickets and roaches), offered at a frequency that matches the spider’s size, age and season. Overfeeding can leave a spider with an overly large abdomen, increasing fall risk in some setups.

Choose feeder insects that have not been exposed to insecticides, and remove uneaten prey so it doesn’t stress or injure the spider.³

Important correction: pet spiders do not need fruit, vegetables, dairy, cuttlebone, or “calcium supplements” in the way reptiles do. Their nutrition comes from whole prey. Offering produce can simply introduce mould, mites and ants.

Water: simple, consistent access beats frequent spraying

Provide a shallow water dish (a clean bottle cap works for small spiders; a heavier shallow dish for larger ones). Refill with fresh water and clean it regularly. Some husbandry guidance recommends avoiding spraying the enclosure and instead relying on a water dish and correct environmental setup for the species.³

Handling and enrichment: less is usually more

Handling is one of the easiest ways to injure a spider, either through falls or stress. Many Australian husbandry guides recommend handling only when necessary, watching behaviour closely, and washing hands beforehand to reduce the risk of introducing pathogens to a vulnerable animal.³

Instead of “exercise”, think in terms of enclosure design:

• Provide appropriate hides and anchor points for webbing.
• Offer a layout that allows natural movement (burrow space or vertical structure, depending on species).
• Keep disturbance low, especially around moulting.

Preventive care that actually helps

• Quarantine new spiders and avoid sharing tools between enclosures.
• Keep it clean, not sterile: spot-clean uneaten prey and waste; replace substrate when needed.
• Stability over tinkering: avoid chasing numbers daily; aim for steady conditions appropriate to the species.
• Document patterns: feeding dates, moults, and any changes in posture or activity.

Veterinary care: when to involve a professional

Not every veterinarian sees spiders routinely, but exotics vets do exist, and early advice can prevent a slow decline becoming a crisis. Seek veterinary help if you see:

• injury or leaking fluid
• persistent inability to stand or right itself
• suspected severe dehydration or a stuck moult
• heavy mite load or signs of infection

A quick safety note for owners in Australia (spider bites and first aid)

If a person is bitten, first aid depends on the spider. Australian guidance is consistent on two key points:

• Funnel-web and mouse spider bites: use pressure immobilisation and seek urgent medical help (call 000).^{4, 5, 6}
• Redback bites: pressure immobilisation is not recommended; cold packs can help with pain, and medical assessment is advised if symptoms are significant or the patient is a child.^{5, 6}

For pet keeping, the safest approach is to avoid free-hand handling, use tools where appropriate, and keep enclosures escape-proof.

Final thoughts

A healthy pet spider is usually the result of quiet routine: a secure enclosure, species-appropriate conditions, clean water, suitable prey, and minimal interference. When something changes, look first to husbandry, then to the spider’s body language over a few days, and don’t hesitate to involve a vet if the signs point to real trouble.

References

1. Queensland Government — Australian tarantulas (family Theraphosidae)
2. Tree of Life Exotic Pet Medical Center — Tarantula care (temperature, humidity, water dish)
3. Northern Territory Government — Keeping spiders as pets (housing, feeding, handling, safety)
4. healthdirect — Spider bites (first aid, pressure immobilisation guidance)
5. NSW Emergency Care Institute — Snake and spider bite clinical tool
6. Australian Museum — Spider bites and venoms (pressure bandage guidance)