Aquatics/Reptiles/Amphibians for NAVLE®

Why may excessive handling of fish lead to heavier external infections with pathogens and possible life threatening ulcerations in the skin?

Excessive handling disrupts the mucus layer of the epidermis

(which protects it from the environment)

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Impression smears of an ulcerated skin nodule on a koi reveal intracellular acid-fast bacilli.
What disease is suspected?

Piscine mycobacteriosis

(a.k.a. fish tuberculosis or fish tank granuloma)

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Ichthyophthirius, commonly known as “ich” is a protozoan parasite that affects the skin of fish. Which of its life stages is most amenable to treatment and why?

The tomite, a free swimming stage in the water

Conversely, the trophozoite (feeding) stages cannot be readily treated because they are within the epidermis.

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Tuberculosis can be seen in fish maintained in tropical fish tanks. Is this zoonotic?

Yes, it is zoonotic

(can cause skin granulomas in humans)

Tuberculosis in fish is caused by Mycobacterium marinum.

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Koi herpes virus has spread worldwide and can cause devastating mortalities in koi. What are the two best measures to take to prevent this disease in a stock of koi and to prevent further spread of the disease?

Purchase fish from reputable sources
Always quarantine new fish

This includes maintaining any new fish in separate systems for ≥ 3 weeks at a temperature of 75°F (24°C).

Use strict biosecurity measures, including disinfection of equipment, water, and controlling movement of fish between ponds or facilities.

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You recommend to the owner of ornamental fish that he add malachite green to the tank water once daily for three days. Which disease are you treating?

Mycoses
Protozoal infections

Mycoses: Saprolegnia spp.

Protozoal infections:

Dactylogyrus spp./gill flukes
Ichthyopthirius multifilis/”ich”

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The operculum of fish reared in captivity is often deformed. How would this affect the health of the fish?

Respiration would be impaired
Gills would be more susceptible to infection, parasitism, and physical damage
Reduced feeding efficiency and growth

(the operculum is the covering of the gills)

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What classic microscopic finding helps diagnose columnaris disease in fish?

“Waving haystacks” of long, filamentous Flavobacterium columnare

(observed on wet mount of skin, fin, or gill lesions)

This distinctive clumping pattern of bacteria along fin rays or lesions is characteristic for columnaris infection.

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What are common risk factors for motile Aeromonas septicemia in freshwater fish?

Poor water quality (low dissolved oxygen, high ammonia)
Trauma
Handling stress

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What is the key treatment consideration for managing velvet disease (Amyloodinium or Piscinoodinium) in captive fish?

Use prolonged, repeated treatment because the parasite’s cyst/tomont stage in the environment can reinfect fish

(making control challenging and prognosis guarded)

Baths with copper sulfate are only option for food fish in the US, or chloroquine for pet fish, to target both attached trophonts and free-swimming tomonts, breaking the parasite life cycle.

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What are the characteristic lesions seen in fish with lymphocystis disease?

Papillomatous or pebble-like “warts” on fins, gills, or skin

(caused by enlarged virus-infected fibroblasts)

These lesions are self-limiting in mild cases but can impair osmoregulation and allow secondary infections if extensive.

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What type of parasite is commonly referred to as a fish louse, and what is a key feature of its impact on fish?

Crustacean ectoparasites (e.g., Lepeophtheirus, Caligus, Argulus) that attach to skin, fins, or gills
Can cause tissue damage or death in heavy infestations.

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A carp presents in spring with smooth, white-to-cream, raised lesions on the skin resembling “candle wax drippings.”
What is the most likely diagnosis?

Carp/koi pox

(caused by Cyprinid herpesvirus-1)

Lesions are benign, self-limiting epidermal hyperplasia that often regress with warmer water temperatures.

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A salmonid presents with hemorrhages in fins, gills, and muscles, and some deep skin abscesses (“furuncles”).
What is the general treatment approach for this condition?

Antibiotic therapy guided by culture and sensitivity

(considering species and legal regulations)

Treatment targets Aeromonas salmonicida infections and may vary with strain, fish species, and regulatory constraints.

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A newly established aquarium shows fish with convulsive swimming, lethargy, and brown-colored blood.
What is the most likely cause?

Ammonia and/or nitrite toxicity due to an underdeveloped biofilter

(“new tank syndrome”)

Manage with water changes and establish a functional biofilter using nitrifying bacteria.

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What water chemistry imbalance is the primary driver of “old tank syndrome” in long-established aquariums?

Severely low or zero alkalinity (buffering capacity)

This often leads to very low pH and biofilter inefficiency.

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A freshwater aquarium has several fish with cloudy eyes, excessive mucus on gills, increased surface respiration, and lethargy.
What should you ask the owner to help identify the cause?

Did they recently added municipal/city tap water containing chlorine or chloramine to the tank without dechlorination?

Suspect chlorine/chloramine toxicosis - both are toxic to fish and cause gill and skin damage if water is not treated before use.

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A fish tank has several fish with exophthalmos, gas bubbles in gills and fins, buoyancy issues, and sudden deaths.
What are common risk factors for this condition?

Use of well water supersaturated with nitrogen
Leaks in pumps or plumbing that pressurize air into water
Any system that introduces excess dissolved gases

Supersaturation of water with gases (usually N₂) causes gas emboli in tissues, similar to “the bends” in divers.

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What are the main drivers of pH changes in freshwater or marine fish tanks?

Water alkalinity (buffering capacity, mainly bicarbonate)
CO₂ concentration

Alkalinity stabilizes pH by buffering acids, while elevated CO₂ lowers pH by forming carbonic acid in the water.

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Which clinical signs might make you suspect that a snake has mites?

Cutaneous: pruritic or nonpruritic dermatitis, dysecdysis
Systemic: norexia, failure to thrive, dehydration, persistent soaking in water

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What are the differential diagnoses for a soft shell in a pet turtle?

Nutritional secondary hyperparathyroidism
Bacterial infection
Fungal infection
Trauma
Normal (softshell turtles - Apalone spp.)

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What does the term “ectotherm” mean, and is this a term that applies to reptiles?

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Yes - it means that the body temperature depends on the environment

Older, synonymous terms: poikilotherm and cold-blooded.

A turtle is presented for evaluation of a mass protruding from the cloaca. What are the most common differential diagnoses?

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Penile prolapse
Urinary bladder prolapse
Cloacal prolapse
Colonic prolapse
Prolapse of the oviduct

A healthy amphibian (e.g., frog or toad) consumes its shed skin. What does this likely indicate?

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Normal process

(failure to do so suggests illness)

The owner of a chameleon was unaware of the importance of regularly exposing the animal to unfiltered sunlight. **What is the risk of failing to do so?**

* Nutritional secondary hyperparathyroidism * Resultant pathologic fractures due to inadequate vitamin D3

The term **dysecdysis** refers to which problem noted commonly in **reptiles**?

Difficult or abnormal shedding of the skin

# Fill in the blank: \_\_\_\_\_\_\_\_ should be **worn** by the clinician when **handling amphibians** to protect the amphibians' sensitive skin.

Powderless vinyl or plastic gloves

You are presented with a **turtle** that is **swimming unevenly** on the lateral plane. Which condition is the top differential diagnosis?

Pneumonia | (with a consolidated lung) ## Footnote A unilateral mass (abscess) or asymmetric gas accumulation (bloating) can result in similar signs.

Which **sensory compromise** may adversely affect a **snake** that has lost its **tongue** (e.g., trauma or infection)?

It may not feed | (due to loss of olfaction)

When performing a **celiotomy** on a **lizard**, you make a **paramedian** incision to avoid this **structure**.

Ventral abdominal vein

Can **castration** reduce the incidence of **interindividual aggression** in male **iguanas**?

Yes, if performed prior to the breeding season | (male iguanas do have testes)

Which normal structure of the **tibiofibular bone** of many **frogs** is routinely **mistaken** for an oblique fracture on **radiographs**?

The nutrient foramen

Which of these three signs is considered a **cardinal sign** of **subcutaneous abscesses** in **reptiles**? * Erythema * Heat * Fever

None ## Footnote In marked contrast to abscesses in mammals, abscesses in reptiles usually show none of these signs.

In **reptiles**, what is the most common location of **uroliths** (urinary bladder vs. kidneys) and what is the typical **mineral composition**?

Urinary bladder (almost never renal); urate salts (almost 100%)

A textbook specifies that an **intramuscular** injection for a **lizard** should **not be administered** in the **tail or hindlimbs**. Why?

Many reptiles, including lizards, have renoportal circulation in the caudal part of the body ## Footnote Injection in this area could lead to nephrotoxicosis, loss of systemic efficacy, or both.

Which animal has an **ear cavity** and a **tympanic membrane**: an iguana or a snake?

Iguana ## Footnote Snakes have neither (they are deaf) and rely mainly on smell and sensation of ground vibrations for sensory input.

An adult **boa constrictor** has developed a deep **bluish tinge** to its **skin** and **spectacles**. What is the cause?

Imminent, normal shedding of skin | (ecdysis)

A large, pulsatile mass effect is visible and palpable at the junction of the proximal and middle thirds of the body of a well-fleshed milksnake. **What is the diagnosis?**

Cardiomegaly ## Footnote It is important not to overinterpret cardiomegaly in emaciated snakes, where the normal heart may be easily palpable.

# True or False: The kidneys routinely should be palpable on an awake, adult iguana.

True | (per cloaca) ## Footnote A gloved, lubricated digit is inserted into the cloaca and the kidneys are palpable within the pelvic canal, on the dorsal aspect.

In **snakes**, the plasma **half-life of gentamicin** given **intramuscularly** is: * A. 2-3 hours * B. 6-8 hours * C. 12 hours * D. > 24 hours

D. > 24 hours ## Footnote It is 10-40 times longer than in mammals, justifying a q72h or q96h interdosage interval.

An adult **iguana** presents for **rhythmic tremors** of the **digits** of the forelimbs. What is the most likely explanation?

Muscle tremors caused by severe hypocalcemia | (typically due to nutritional deficiency)

What is the most common clinical disorder caused by **herpesvirus infection** in **tortoises**?

Stomatitis and rhinitis

When administering medications or fluids to a **lizard** by **intracoelomic injection**, you are careful to insert the needle in the ventrocaudal coelomic cavity, slightly off midline, to avoid **two important structures**. Which ones?

1. The lungs by being located ventrocaudally 2. The ventral abdominal vein by being paramedian

Your **radiograph** of a **sea turtle** identifies a **fishhook** in the stomach. Other than perforation, what are your **two concerns**?

1. Gastrointestinal obstruction, since fishing line attached to the hook often traps plastic and other debris 2. Lead toxicosis, since lead weights/sinkers can be attached to the hook via fishing line

What is the purpose of the **"drink patch,"** a thin, highly vascular area of skin on the ventrum of anurans (e.g., toads)?

Water absorption ## Footnote It should not be mistaken for a defect in the skin or an area of infection or septicemia.

An adult slider turtle has a circumscribed, firm subcutaneous swelling in the cranial neck, ventral and caudal to the eye. The diet is not nutritionally balanced. **What is the most likely diagnosis?**

Aural abscess

A male lizard is presented for evaluation of recent-onset swelling of the ventral tailbase, adjacent and caudal to the cloacal opening. **What is the most likely diagnosis?**

Possible causes: * Normal enlargement of the hemipenes with sexual maturity * Abnormal debris accumulation (seminal plugs) * Infected hemipenes

What is the most common cause of **generalized swelling of the limbs** in herbivorous and insectivorous **lizards**?

Nutritional secondary hyperparathyroidism leading to fibrous osteodystrophy

Which common disease of **captive water turtles** is typically associated with **blepharedema**, lethargy, anorexia, **weight loss**, and nasal and ocular discharge?

Hypovitaminosis A

Which common disease of **reptiles** results from prolonged **deficiency** of dietary **calcium** or **vitamin D3**?

Nutritional secondary hyperparathyroidism | (a.k.a. metabolic bone disease, rickets, or hypovitaminosis D)

Temperate zone **reptiles** regularly undergo **brumation**. What is this?

A period of winter dormancy that occurs when temperatures drop

What is the main reason an owner would want you to **castrate** his/her healthy male green **iguana**?

Intact male green iguanas can become very aggressive during the breeding period | (notably towards the owners)

What are two potential causes of **dysecdysis** in **snakes**?

* Mites * Incorrect humidity * Lack of a proper substrate (contact surface) * Malnutrition * Dermatitis * Trauma ## Footnote All may be associated with incomplete shedding of the skin (dysecdysis).

While you are handling a gecko, a large portion of its tail suddenly detaches and remains in your hands. **What is the most likely cause?**

Normal defense/escape mechanism ## Footnote Not indicative of nutritional, endocrine, or other similar disease.

Aquatics/Reptiles/Amphibians Flashcards

Assess the anatomy, husbandry, and health of aquatic animals, reptiles, and amphibians to support proper diagnosis, welfare, and disease management. (54 cards)