FYI Articles 6

<---A Chameleon disguised as an iguana

Chameleons: Biology, Husbandry and Disease Prevention

by Paul Stewart, DVM

Number of Species: 150 identified

Size: From 3.3 cm to 68 cm in length

Origin: Africa (40% of species) and Madagascar (40% of species)

Also found in Sicily, Spain, Arabia and India

Longevity: 4-6 years-males, 2-4 years females

Unique Morphology:

-Body laterally compressed (useful for thermoregulation, hiding and color display)

-Eyes laterally placed (for defense and food location)

-Eye movement is independent

-Some have crests, horns and modified scales (for camouflage, defense and secondary sex characteristics)

-Teeth are not regenerative

-Prehensile tail is will not grow back if pulled off

-Feet have opposing sets of toes: front=3 inner and 2 outer fused digits, rear have 3 outer and 2 inner fused digits

-Parietal eye on top of the skull

-No tympanic membrane

-Skin cells that allow color change and camouflage

          -melanophores contain black pigment

          -xanthophores contain yeool and red pigment

          -guanophores reflect a blue color

-external influences (temperature, light intensity, time of day, seasonal change)

-internal influences (health, gestation, nutrition, visual communication)

Reproduction:

-Females can store sperm

-Males: swollen tail base and are often larger and more colorful

-Females: slightly shorter thinner tails with duller color patterns (except during pregnancy)

          -Breeding season is year round

          -Sexually mature at 4-8 months

          -Gestation 20-30 days

          -Clutch size 2-60 eggs

Species commonly kept:

-Veiled chameleon

-Jackson’s chameleon- (live-bearers)

-Panther chameleon

-Flap-necked chameleon-

-Common chameleon

-Parsons chameleon

*Anoles are not chameleons

Husbandry:

Caging: (house separately after 3 months of age)

-Plastic or vinyl screen cages (avoid metal screen)

-Plastic coated wire mesh cages

-Aquariums with well-ventilated lids can be used short term for hatchlings

-Should contain adequate plants, branches and rope perches for easy access to food, water, hiding and basking

Substrate: Newspaper, brown paper towels, sterilized potting soil

Plants:

-Ficus, hibiscus, pothos

Diet: (for insectivores)

-Feed appropriately gut-loaded crickets, mealworms, wax-worms, flies, grasshoppers

-Feed daily as juveniles, every 2 days as adults.

-Should feed separately to avoid injury.

-A salad of mixed appropriate greens can be offered for adults (veiled chameleons).

-If not gut-loading your insect food items, supplemental dusting with a balanced formulated calcium and vitamin powder is necessary. For growing or pregnant chameleons, a safe calcium supplement should be provided each meal. For adult non-breeding chameleons, twice weekly calcium supplement is adequate. A balanced vitamin powder should be supplemented 2-3 times per week in growing or pregnant chameleons, weekly in adult non-breeding chameleons.

Water:

-Misting (twice daily) with spring water (85 degrees)

-Drip systems (constant water source)

-Water bowls (for larger individuals)

-Pipette watering (once daily for juveniles, once every other day for adults)

-Routine disinfection of water storage device is needed to prevent bacterial overgrowth

Lighting:

-A full spectrum fluorescent bulb that emits UVA and 5%-8% UVB should be used during daylight hours for general cage lighting.

-An incandescent heat bulb or ceramic heat bulb can be used to provide a focal basking site, placed at a safe distance from the chameleon (closely evaluate temperature under the basking source to prevent thermal injury).

Thermal gradients: (species-dependant)

-Provide optimum daytime and nighttime ambient temperatures and daytime basking temperatures for the species you keep (either with an incandescent heat bulb or ceramic heating bulb). -For larger cages, the room temperature may need to be controlled.

Humidity: (species-dependant ranging from 40% in desert dwelling

          species to 80% in tropical species)

-This can be provided with room humidifiers, misting, drip systems and damp sphagnum moss in plant pots (kept moist).

Disease prevention:

          -Learn specifics on the care of the species being kept.

-Prepare an optimum enclosure.

-Start with a captive bred moderately sized well hydrated juvenile (3 months old), that is active, alert, strong, free of swellings and bruises, and has been cared for appropriately.

-Schedule a post-purchase exam/parasite screen and regular annual check-ups.

-Quarantine for 60 days if introducing into an existing reptile collection.

Common diseases:

-Parasites

          -Egg binding

          -Toe injuries/infections

          -Abscesses

          -Mouth rot  

-Secondary nutritional hyperparathyroidism (a form of metabolic bone disease)

Visit www.animalarkshelter.org/cin/ for Chameleon Information Network

Corneal ulcers (ulcerative keratitis)

Clinical relevance:  Given the option, a pet would choose to keep his or her eyesight

Corneal anatomy:

Epithelium: the thin outermost layer - five cells thick
Stroma: thick connective tissue layer
Descemet’s membrane and endothelium: a very thin sheet of cells lining the back-side of the cornea

By definition:  A corneal ulcer is a loss of the epithelial layer of the cornea, as well as a variable amount of loss of the underlying stroma.

Size:  The ulcer can vary from a small pinpoint ulcer to ulceration of the entire cornea.

Causes:

1. Trauma (foreign body, abrasion, blunt trauma, entropion, dystichia, eyelid growths,)

2. Irritant (chemicals, particulates)

3. Dryness (low tear production [K.C.S.-keratoconjunctivitis sicca], facial paralysis, anesthesia, ectropion, exophthalmic breeds)

4. Virus (herpes - cats only)

5. Defects with the cornea (edema from chronic glaucoma, senile keratopathy)

Symptoms:

•  Pain, squinting, excessive blinking

•  Excess tear production (except in dry-eye patients -K.C.S.)

•  Cloudy discharge from the eye

Diagnosis:

Flourescein dye is applied to the corneal surface for a short time. Then the eye is flushed with saline and the cornea is inspected for remaining dye. Flourescein will stick to the stroma but not the cornea or the Descemet’s membrane.

If an ulcer is present, it is evaluated to determine the size, depth, and severity. Therapy is instituted based on this data, as well as the cause and the condition of the patient.

Risks:

• If untreated, superficial ulceration can become deep ulceration.

• Deep ulceration can become a descemetocele (outward bulging of the innermost membrane through the ulcerated hole in the stroma).

• A descemetocele can rupture leading to leaking of the aqueous humor, iris prolapse and endopthalmitis (infection/inflammation of the inside of the eye).

• Infection (as with pseudomonas bacteria) can cause protein-digesting enzymes that can speed the progression of the ulcer.

• Steroids (topical and systemic) can speed the progression of an ulcer by slowing epithelial growth and intensifying protein-digesting enzymes.

• Secondary uveitis (inflammation within the eye) can occur due to corneal ulcers.

Goals of therapy:

   1.  Address the underlying cause.
   2.  Halt progression of the ulcer.
   3.  Provide the best healing environment possible.

Therapeutics:

   1.   Lubricants:
            Artificial tear drops/ointment may be prescribed if needed.
            Cyclosporin if K.C.S. (dry-eye) is a concurrent diagnosis.

   2.  Pain control:
            Atropine (1%) is used to reduce pain from muscle spasms caused by the anterior uveitis.
            Atropine also prevents adhesions of the iris by dilating the pupil.

   3.  Nutrients:
            Serum separated from the patients own blood are often used
            These drops fortify the healing environment by providing nutrients, antibodies and lubrication.

   4.  Antibiotics:
            Topical +/- systemic antibiotics may be chosen empirically or based on culture and sensitivity.

   5.  Protease inhibitors:
            Acetylcysteine (Mucomyst) may be needed to slow degeneration of the stroma.
            Serum drops also inhibit proteases.

   6.  Steroids:
            Topical steroids like prednisolone acetate may be used to minimize scarring.
        Only used after the ulcer has completely healed.

Physical and surgical therapy:  (options are selected case by case):

1. Corneal debridement: Physical removal of diseased tissue (usually accomplished with topical anesthesia).

2. Superficial Grid keratotomy: Making tiny grooves in the stroma to provide scaffolding for the epithelium to heal across the ulcer. Topical anesthesia is needed.

3. Third eyelid flap: The third eyelid is suture into position to protect the cornea and keep it moist as it heals. The flap is let down for examination in 7-10 days. General anesthesia is needed.

4. Conjunctival flap: A flap of tissue from the conjunctiva is temporarily sutured across the cornea. This technique is usually elected to prevent rupture of the globe when deep corneal ulceration is present. The flap provides protection, nutrition and blood supply to a  healing ulcer. General anesthesia is needed.

5. Tissue adhesive: Alternative therapy for mild to moderate ulcers. A drop of tissue adhesive is used on the ulcer to protect it while it heals. This option can be successful in certain cases. General anesthesia is needed.

*Elizabethan collars are usually needed when treating ulcers surgically to prevent trauma to the surgical site or to the ulcer.*

Follow up: Corneal ulcers need to be rechecked frequently. It is not uncommon to have rechecks every 1-5 days depending on the case.

Prognosis: Good to excellent with proper care given in reasonable time.

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