Reptile / Aquatics Flashcards
You visit a fish hatchery and need to perform anesthesia on a fish to remove a foreign body. Which of these agents is approved for use in fish and what additional rules apply to its use?
- Tricaine methanesulfonate (MS 222) - There is a 21 day withdrawal period before the fish can be consumed by humans
- Chloral hydrate - There is a 14 day withdrawal period before the fish can be consumed by humans
- Benzocaine hydrochloride - A mask and eye protection should always be worn when handling this agent
- Halothane - must be used in a vacuum system to collect volatile gas
- Clove oil (Eugenol) - This can only be used in animals that will not be consumed by humans
Answer: Tricaine methanesulfonate (MS 222) - There is a 21 day withdrawal period before the fish can be consumed by humans
Explanation
Also known as Finquel, tricaine methanesulfonate (MS-222) is the only FDA approved agent for fish anesthesia.
There is a mandatory 21 day withdrawal period before the fish can be used for consumption. The other agents listed have been used for fish anesthesia but are not FDA approved.
***PowerPage: Aquatics: Environmental Management and Clinical Procedures
A producer raising seahorses for the aquarium trade brings you several seahorse fish to examine and necropsy because they have concerns about Mycobacteriosis problems in their facility. You identify granulomas in multiple organs via wet mount, and impression smears are acid fast positive. You advise the producer that seahorses are particularly susceptible to Mycobacteriosis, and that there is no effective treatment. What else do you need to be sure to inform the producer of?
- Mycobacteriosis is zoonotic and may cause Fish Handler’s Disease, a condition that presents as a chronic skin injury on the hands where water or fish was touched.
- Mycobacteriosis in fish is caused by the same species that causes respiratory disease in cattle and people.
- Fish, cattle, and humans all experience the same symptoms.
- Mycobacteriosis in fish is an OlE reportable aquatic pathogen that may cause high mortality. The producer should be prepared to depopulate his entire facility.
- Mycobacteriosis is easily prevented in seahorses with prophylactic antibiotic treatments and enhanced biosecurity, such as quarantining new seahorses and using separate nets for different tanks.
Answer: Mycobacteriosis is zoonotic and may cause Fish Handler’s Disease, a condition that presents as a chronic skin injury on the hands where water or fish was touched.
Explanation
Mycobacteriosis in fish is commonly caused by Mycobacterium marinum, but other Mycobacterium spp. may cause disease as well. M. marinum is an extremely important disease of seahorses, sea dragons, and striped bass that may cause high mortality. It causes granulomas in many internal organs. Mycobacterium marinum is an acid-fast positive organism that does not gram stain well. There is no effective treatment for Mycobacteriosis, and prevention through good biosecurity is critical. This is not an OlE Reportable Aquatic Pathogen, but it is zoonotic. Most immunocompetent people should not be worried, but it can cause Fish Handler’s Disease as described above in immunocompromised people.
Mycobacterium bovis causes disease in cattle and may cause disease in humans. Symptoms in cattle tend to be respiratory related, while humans, in addition to respiratory symptoms, may experience a variety of clinical signs.
***PowerPage: Aquatics: Disease-Causing Agents
A state fish and wildlife agency calls you looking for advice about how to anesthetize lake trout broodstock for a tagging procedure. They have historically used clove oil but recently discovered that it is not FDA-approved and therefore illegal to use in food fish. They are concerned about fish welfare during the tagging procedure and are hoping that you can refer them to a product that they can use to legally anesthetize food fish. You advise them that:
- Eugenol is legal with a 10-day withdrawal
- MS-222 is legal with a 21-day withdrawal
- Clove oil is legal with a veterinary prescription
- Metomidate is legal as an Investigational New Animal Drug
- Alfaxalone is legal with no withdrawal
Answer: MS-222 is legal with a 21-day withdrawal
Explanation
MS-222, also known as “Triple 2” or Tricaine methanesulfonate, is the only FDA-approved drug labeled for anesthesia legal to use in food fish. It has a 21-day withdrawal according to the label. It is extremely acidic and should be buffered by weight with baking soda to prevent fish from developing skin and eye lesions. Aqui-S is a solution containing 10% eugenol and may be legally used in some food fish as an Investigational New Animal Drug (INAD). Fish in the field may be released back into their natural environment with no withdrawal period for Aqui-S. Fish in a hatchery environment must undergo a 72 hour withdrawal period. Metomidate and clove oil are illegal to use as anesthetic agents in food fish. Alfaxalone can be used extralabel in food fish, but an extended withdrawal period must be established.
***PowerPage: Aquatics: Environmental Management and Clinical Procedures
Which organization is responsible for regulating the food safety of salmon in the United States?
- EPA (Environmental Protection Agency)
- FAO (Food and Agricultural Organization)
- FDA (Food and Drug Administration)
- USDA (United States Department of Agriculture)
Answer: FDA (Food and Drug Administration)
Explanation
The correct answer is FDA. The USDA is responsible for meat and poultry products including egg products. The FDA regulates other foods, food labels, use of veterinary drugs, and seafood. The EPA is responsible for pesticides and water standards. The FBI is responsible for food counter-terrorism. The FAO is a United Nations entity.
FYl, an exception to the rules above is from the 2008 Farm Bill which amends regulations such that catfish are subject to examination and inspection by USDA’s FSIS when processed for use as human food.
A juvenile tortoise presents for difficulty eating due to an overgrown beak. You trim the mouth parts to make a more normal conformation. What do you tell the owner regarding management of the tortoise?
- The tortoise will require beak trimmings until it reaches its full size
- The condition usually does not recur after the first trimming
- Calcium supplementation will prevent requiring future beak trimmings
- The condition usually recurs from primary malocclusion and will likely need long term maintenance
Answer: The condition usually recurs from primary malocclusion and will likely need long term maintenance
Explanation
The correct answer is the condition usually recurs from primary malocclusion and will likely need long term maintenance. Abnormal beak growth in turtles is often associated with hypocalcemia causing distortion of the skull as the animal grows. Supplemental calcium is unlikely to affect the skull’s formation once distortion has already occurred.
A full spectrum source of ultraviolet light is required for reptiles for which of the following reasons?
- Conversion of inactive vitamin D to vitamin D3 in the skin
- Conversion of beta-carotene to vitamin A
- Proper absorption of calcium and magnesium in the gut
- Proper absorption of vitamin D in the gut
- Proper incorporation of iodine into thyroid hormone
Answer: Conversion of inactive vitamin D to vitamin D3 in the skin
Explanation
The correct answer is conversion of inactive vitamin D to vitamin D3 in the skin. Animals housed outside with access to direct sunlight usually have adequate amounts of vitamin D3.
Vitamin D3 is required for proper calcium absorption and metabolism. Imbalances in calcium, phosphorus, and vitamin D3 can lead to nutritional secondary hyperparathyroidism, fibrous osteodystrophy, osteomalacia, cystic calculi, bone deformities, and rickets.
Deficiencies in vitamin D3 can be corrected with parenteral administration of vitamin D3 every 4 weeks.
Overdoses of vitamin D3 can lead to soft tissue mineralization.
The snake in the image below is being irradiated with a Strontium-90 probe. Strontium-90 radioactively decays and emits beta particles which allow delivery of very high doses of radiation to a small superficial area. All of the following are considered important principles of radiation protection for personnel (radiation workers) that should be followed EXCEPT for which of the following?
- Plexiglass shielding should be used to decrease radiation exposure to personnel
- Pregnant women should not handle a Strontium probe
- All personnel should hold the Strontium probe for the minimum amount of time that is necessary
- All personnel should stand as far away from the Strontium probe as is reasonably achievable
Answer: Pregnant women should not handle a Strontium probe
Explanation
Significant knowledge about Strontium is not necessary to answer this question correctly. The principle of ALARA (as low as is reasonably achievable) should always be followed when dealing with radiation, regardless of the type of radiation.
This means that you should always take reasonable steps to keep radiation dose to personnel as low as you reasonably can. The 3 main ways to decrease radiation dose are to increase the distance of personnel from the radiation source, to decrease the time of exposure of personnel to radiation, and to use appropriate shielding to decrease radiation to personnel. The same principle holds true for pregnant women.
There are acceptable exposure limits for pregnant women (the most commonly used is <0.5 milliSieverts per month during pregnancy). If steps are taken to keep exposure as low as reasonably achievable, pregnant woman would be able to handle the Strontium probe and keep the dose well below these limits.
Which of the following is not a cause of metabolic bone disease in reptiles?
- High Ca:P ratio
- Lack of ultraviolet light
- Vitamin D deficiency
- Low calcium diet
Answer: High Ca:P ratio
Explanation
The correct answer is high Ca:P ratio. This ratio would indicate there is an adequate amount of calcium and would not predispose to metabolic bone disease. Whenever there is not enough calcium either as a result of decreased calcium in the diet or not enough vitamin D, calcium is resorbed by osteoclastic resorption in order to maintain serum levels. This leads to weak, pliable bones which are susceptible to fracture.
Which of the following is a common isolate in infectious stomatitis in turtles?
- Salmonella spp
- E. coli
- Pasteurella spp
- Citrobacter spp
- Aeromonas sp
Answer: Aeromonas sp
Explanation
The correct answer is Aeromonas spp. Infectious stomatitis occurs commonly in lizards, turtles, and snakes.
Aeromonas and Pseudomonas spp are commonly isolated from the lesions. Clinical signs include petechiation and caseous material build up within the mouth. Treatment is aimed at debridement and antibiotics.
A turtle is presented to you for diarrhea. You diagnose a nematode infection on fecal smear. Which of the following is not a treatment option for the turtle?
- Levamisole
- Ivermectin
- Mebendazole
- Fenbendazole
- Thiabendazole
Answer: Ivermectin
Explanation
The correct answer is ivermectin. Ivermectin is highly toxic in turtles and causes paresis, paralysis, and death at low doses. Ivermectin is not recommended in turtles despite its efficacy in treating nematode infections.
An adult male iguana, fed a poor diet high in protein and low in vitamins, presents with a history of lethargy, inappetance and abdominal straining with the voiding of small amounts of red-tinged urates. You palpate a firm mass in the caudal abdomen which is confirmed with radiographs. At this time what is your best diagnosis and therapeutic response?
- Hepatomegaly caused by Iguana septicemia virus (ISV), begin antibiotics and monitor regression of liver size with monthly radiographs
- Renal tumor caused by Inclusion Disease Virus, start corticosteroids for immediate immunosuppression
- Cystic calculi and surgical removal
- Gastric foreign body, promote regurgitation by providing a cathartic such as psyllium or ipecac
Answer: Cystic calculi and surgical removal
Explanation
Iguanas are predisposed to developing large cystic calculi if they are fed an imbalanced/improper diet.
Radiographs contribute to the diagnosis, which show classic round cystic calculi within the bladder. If the calculi are large such that they will not pass, surgery may be indicated. In order to promote proper healing and to decrease the chance of calculi recurrence, a balanced diet appropriate for iguanas must be provided.
***PowerPage: Iguana Husbandry and Physiology
What is the best method to prevent a retained spectacle in snakes?
- Apply prophylactic triple antibiotic ointment
- Apply cyclosporine drops to the eyes
- Provide proper husbandry
- Provide a dry environment at time of shedding
Answer: Provide proper husbandry
Explanation
The correct answer is provide proper husbandry. Retained spectacle usually results from improper shedding (dysecdysis) at the level of the eye due to dry conditions. You never want to pull on these “spectacles” as you will damage the eye. Provide adequate moisture and they will resolve on their own.
A 3 year old king snake presents for retained spectacles after shedding. Which of the following should not be advised to the client?
- Increasing humidity in the environment for several days
- Apply an ophthalmic ointment several times daily until the eyecaps soften and fall off
- Use forceps to grasp the eyecaps and peel them off
- Consider searching for other underlying diseases
Answer: Use forceps to grasp the eyecaps and peel them off
Explanation
The correct answer is use forceps to grasp the eyecaps to peel them off. Dysecdysis or incomplete shedding is often due to low humidity, lack of abrasive substrates to rub against, or other stresses such as ectoparasitism, nutritional deficiencies, or other systemic disease. Retained spectacles should never be forcibly removed because of the possibility of corneal damage. Increasing moisture in the environment by increasing humidity or by applying ophthalmic ointments to the eyecaps can often help.
A boa constrictor presents to you for weight loss, vomiting, hemorrhagic diarrhea, and anorexia. The snake is housed with herbivorous turtles, which all seem to be healthy. What pathogen should you be suspicious of?
- Citrobacter spp
- Entamoeba spp
- Aspergillus spp
- Plasmodium spp
- Salmonella spp
Answer: Entamoeba spp
Explanation
The correct answer is Entamoeba spp. Entamoeba invadens is a protozoal organism that causes severe gastrointestinal signs and death in snakes. Turtles act as carriers for the protozoa but are clinically unaffected.
Diagnosis is based on identification of trophozoites or cysts in fecal smears or histologic sections.
Metronidazole is the treatment of choice. Turtles and snakes should not be housed together.
You receive a message from a koi owner who has been experiencing moderate mortality in their pond this summer. You arrive at midday and perform water quality testing, the results of which are provided (see image). They report that many fish have severe skin lesions that are red and raised with deep ulcers exposing the underlying muscle. New fish were added to the pond this past fall. The owner was hesitant to call you at first, because they were worried they might need to depopulate their pond. You call them back and inform them that:
- The prognosis is excellent with no treatment
required. - The prognosis is excellent with salt treatment.
- The prognosis is guarded and depopulation is recommended.
- The prognosis is good with antibiotic treatment.
- The prognosis is grave and depopulation will
be required.
Answer: The prognosis is good with antibiotic treatment.
Explanation
The top differential diagnosis for this case is
“Furunculosis” caused by Aeromonas salmonicida.
The classic clinical sign is large, swollen skin lesions mistakenly referred to as “furuncles” (since fish don’t have hair). Other clinical signs include hemorrhage, kidney and vent swelling, and ulcers.
For food fish, furunculosis may be treated with oxytetracycline, sulfadimethoxine and
ormetoprim, and florenicol medicated feeds via a Veterinary Feed Directive. In a koi pond, you may use injectable antibiotics if the population is small.
If left untreated, furunculosis may lead to serious mortality.
Koi herpesvirus (Cyprinid herpesvirus Type 3) is not a top differential because mortality at this temperature would be extremely high, approaching 80-100% if new fish had been introduced several months ago. Clinical signs of KHV include gill necrosis and enophthalmia. The clinical signs in this case are also not indicative of Spring Viremia of Carp. Spring Viremia of Carp would present with extremely high mortality and internal ecchymotic hemorrhages. SVC also usually presents at a lower temperature (50-64°F).
A quarantine protocol and improved biosecurity measures may be helpful to discuss with the owner since they introduced new fish recently.
***PowerPage: Aquatics: Disease-Causing Agents
You are called to examine a newly acquired swordtail fish in a home aquarium. It has a saddle-shaped lesion on the dorsum behind the dorsal fin with associated yellow pigment. Water quality testing results are below. You anesthetize the swordtail fish with buffered tricaine methanesulfonate and perform a skin scrape and gill biopsy. The skin scrape below reveals haystack structures composed of many long, thin, flexing bacterial rods. If you performed a skin impression, this organism would stain:
- Non-staining
- Gram-positive
- Gram-negative
- Acid-fast positive
Answer: Gram-negative
Explanation
The water quality for this swordtail is all within normal limits. Most fish bacterial pathogens are Gram-negative rods. This fish is presenting with a Flavobacterium columnare infection, known as Columnaris Disease. Upon skin scrape, F. columnare looks like long, flexible rods stacked close together, which give the appearance of a haystack. They characteristically produce yellow-pigmented lesions on the skin. The most common gram-positive bacterial pathogens in fish are those in the Streptococcus genus, but they would be cocci, and not long thin rods, as described. A common acid-fast positive bacterial pathogen is Mycobacterium marinum, which causes internal granulomas, not yellow skin lesions. A good differential for Mycobacterium marinum is Francisella noatunensis. Francisellosis also causes granulomas, but is acid-fast negative.
***PowerPage: Aquatics: Disease-Causing Agents
