Teleosts Flashcards
What are the three forms of iodine in seawater and which is not biologically available for uptake across the gills?
What other environmental factors contribute to iodine bioavailability?
A CLUSTER OF CASES OF THYROID HYPERPLASIA IN AQUARIUM-HOUSED TROPICAL MARINE TELEOSTS FOLLOWING A CHANGE OF SALT MIX BRAND
Marion Jalenques, Claire Vergneau-Grosset, Noémie Summa, Wahiba Ait Youcef, Jean-Francois St-Cyr, Stéphane Lair
J. of Zoo and Wildlife Medicine, 51(3):725-728 (2020).
Key Points:
Large goiter may lead to inhibition pharyngeal region → difficulty respiring eating → death
Iodine exists as iodate (IO3-), iodine (I2), and iodide (I–); Iodate is not available for absorption across gills/GI
Iodate (IO3-) = 96% of it, not available
Iodide (I-) = Biologically active, thyroid hormone synthesis
Iodine (I2) meas by spectrophotometry - May significantly underestimate the biologically available forms of iodine in the system
Measuring total water iodine does not differentiate the forms (I- vs IO3-)
Ozone (O3) - converts iodide (I-) to iodate (IO3-)
High nitrate concentrations competitively inhibit thyroid utilization of iodine
Tx - Can add potassium iodide or Lugol’s to water; iodine dietary supplementation; maintain nitrate concentrations
Conclusions: Check the iodine concentrations in the water! Thyroid hyperplasia - iodine deficiency
What was observed in gold fish anesthetized by propofol immersion at 5 and 10 mg/L?
Did propofol affect MAC following repeated exposure? Does MS-222?
PROPOFOL AS AN IMMERSION ANESTHETIC AND IN A MINIMUM ANESTHETIC CONCENTRATION (MAC) REDUCTION MODEL IN GOLDFISH (CARASSIUS AURATUS)
Julie A. Balko, V.M.D., Sarah K. Wilson, B.A., Gregory A. Lewbart, M.S., V.M.D., Dipl. A.C.Z.M., Brian R. Gaines, B.A., M.S., and Lysa P. Posner, D.V.M., Dipl. A.C.V.A.A.
Journal of Zoo and Wildlife Medicine 48(1): 48–54, 2017
Background:
MAC: the alveolar concentration of an anesthetic agent at which 50% of the population will not respond to supramaximal stimulus with gross purposeful movement
Allows for the comparison of analgesic potency
MAC model was recently validated in goldfish with MS-222
MS-222 repeat exposure requires increasing doses
Key Points:
Propofol immersion at 5 and 10mg/L → consistent anesthesia with rapid, dose-dependent induction (<5 min)
Opercular rates dropped to almost zero in most (70%) in both groups
Physiologic parameters were otherwise normal
MAC did not change following repeated exposure (in contrast to MS-222)
MAC ws reduced with dexmedetomidine at 0.04mg/kg, but not butorphanol, morphine, ketoprofen, or lower dexmed
No deaths in phase I of anesthesia, only deaths in phase IV. Propofol is safe for goldfish.
Conclusions: In goldfish, propofol immersion with 5 and 10 mg/L produces anesthesia and MAC does not change with repeated exposures. MAC was decreased with dexmedetomidine 0.04 mg/kg.
What is the only anesthetic approved for use in fish by the FDA?
What was observed regarding the effect of ax time on physiologic status of koi?
THE EFFECT OF ANESTHETIC TIME AND CONCENTRATION ON BLOOD GASES, ACID-BASE STATUS, AND ELECTROLYTES IN KOI (CYPRINUS CARPIO) ANESTHETIZED WITH BUFFERED TRICAINE METHANESULFONATE (MS-222)
Parker-Graham CA, Lima KM, Soto E.
Journal of Zoo and Wildlife Medicine. 2020 Mar;51(1):102-9.
Key Points:
MS-222 at 100 and 150 mg/L induced Stage III anesthesia in all fish within 5 min
Dose- and time-depending increases in pCO2 and hyperglycemia and decrease in potassium
Time-dependent decrease in pO2 with increased anesthetic time
Decrease in pH and tCO2, more in 150mg/L group; lactate decreased in both groups
Conclusions: MS-222 at 100-150 mg/L increases pCO2, hyperglycemia and decreases potassium and pO2.
What type of virus is carp edema virus?
Clinical signs?
OUTBREAK AND TREATMENT OF CARP EDEMA VIRUS IN KOI (CYPRINUS CARPIO) FROM NORTHERN CALIFORNIA
Stevens BN, Michel A, Liepnieks ML, Kenelty K, Gardhouse SM, Groff JM, Waltzek TB, Soto E.
Journal of zoo and wildlife medicine. 2018 Sep;49(3):755-64.
Poxvirus aka sleepy koi dz
Most significant histo findings in gills - necrotizing branchitis, intranuclear inclusion bodies; PCR gill and kidney tissue positive
Extensive erosions, edema of underlying tissue, inflammation of vent.
Dx - Virus most abundant in gill; light microscopy, TEM, PCR; severe epithelial hyperplasia and edematous changes
Outbreak management:
0.5% salt water holding following stress
Reduced proliferation of CEV
Avoid harvest of koi when water temps are permissive
Management and control:
No treatment
Prevent introduction
Source fish from reputable suppliers
Disease-free broodstocks
Biosecurity, disease surveillance
Quarantine and testing
30 days between 15-25C
Fish returning from koi shows
Avoid crowding, stress
Water quality, nutrition
How does anesthesia and lead toxicity affect voltage in electric eels?
CLINICAL SIGNS, DIAGNOSIS, AND TREATMENT OF LEAD INTOXICATION IN AN ELECTRIC EEL (ELECTROPHORUS ELECTRICUS)
Sandra Wenger, Helene Pendl, Stamatios Tahas, Monika Bochmann, Jean-Michel Hatt
J Zoo Wildl Med. 2018 Dec 13;49(4):1029-1031. doi: 10.1638/018-0006.1.
Case: Electric eel ate lead wire and developed lead toxicity
Signs: Bilateral swellings behind the pectoral fins (distended, flaccid stomach), lethargy, anorexia
Elevated blood lead values
Treated with CaEDTA injections, then dimercaptosuccinic acid (DMSA) orally
Key Points:
Electric eels are obligate air breathers, majority of O2 absorption occurs in oral cavity
Voltage in eels is voluntary and can be used to monitor depth of anesthesia
Had a decreased voltage response with lead poisoning compared to other measurements
Voltage normalized once lead treated
Conclusions: An electric eel suffering lead poisoning had a flaccid, distended stomach and was treated successfully with chelating agents.
What organs could be visualized well during cranial or caudal celioscopy of koi?
Which organs were not visualized?
Evaluation of diagnostic coelioscopy in koi (Cyprinus carpio).
Stevens BN, Guzman DS, Phillips KL, Camus AC, Soto E.
Am J Vet Res. 2019 Mar;80(3):221-229.
Key Points:
Approach: Incision on ventral midline cranial or caudal to the pelvic girdle
For both approaches (no diff):
Good visualization of anterior kidney, gonads, intestines, and liver
Difficult visualization of swim bladder and posterior kidney
Unable to view spleen and gallbladder
Occasional hemorrhage and ruptured gonad capsule
Two week post op: Incomplete healing, redness,and swelling but good reepithelialization
Eight weeks post op: half of the koi were not fully healed
Approach caudal to the pelvic girdle was easier to view structures
Conclusions: Celioscopy with an cranial or caudal to the pelvic girdle in koi can view anterior kidney, gonads, intestines, and liver +/- swim bladder, posterior kidney. Spleen and gallbladder were not visualized. Caudal approach was recommended as more comfortable. Definitely take sutures out of fish by like 7-10 days unless you want a horrible inflammatory reaction.
What was observed in evaluating KCl as a second step for euthanasia of koi via IC, ICe, and topical application to the gills?
EVALUATION OF POTASSIUM CHLORIDE ADMINISTERED VIA THREE ROUTES FOR EUTHANASIA OF ANESTHETIZED KOI (CYPRINUS CARPIO)
Meghan M. Louis, Emma L. Houck, Gregory A. Lewbart, Lysa P. Posner, Julie A. Balko
J. of Zoo and Wildlife Medicine, 51(3):485-489 (2020).
Intracardiac KCl at 10 mEq/kg rapidly ceases Doppler sounds and is a successful technique for euthanasia of anesthetized koi.
Intracoelomic and topical KCl at 10 mEq/kg were not effective for euthanasia of koi.
Conclusions: KCl administered intracardiac after MS222 immobilization resulted in cessation of heart rate and opercular movement, but intracoelomic and topical routes did not.
How do teleost fish IOPs compare vs mammals and birds? How did IOP differ in trout when immobilized with electronarcosis vs MS-222?
A PRELIMINARY STUDY OF INTRINSIC AND EXTRINSIC FACTORS INFLUENCING INTRAOCULAR PRESSURE IN BROOK TROUT (SALVELINUS FONTINALIS)
Lamglait B, Jalenques M, Summa N, Youcef WA, Vergneau-Grosset C.
Journal of Zoo and Wildlife Medicine. 2021 Jan;51(4):1012-6.
IOP in fish measured in ventral recumbency with rebound tonometry
Fish IOPs are lower than mammals and birds
Fish anesthetized with electronarcosis had higher IOPs than those in MS-222
Causes electrotetany
Conclusions: IOP significantly higher in brook trout when immobilized with electronarcosis vs. MS-222.
What was observed following enrofloxacin IM injections in striped bass?
Evaluation of localized inflammatory reactions secondary to intramuscular injections of enrofloxacin in striped bass (Morone saxatilis)
Scott G, Law M, Christiansen EF, Lewbart GA, Harms CA.
Journal of Zoo and Wildlife Medicine. 2020 Mar;51(1):46-52.
Key Points:
Enrofloxacin 2.27% is basic (pH 11.5) and causes tissue site reactions in mammals
Fish injected with enrofloxacin 2.27% IM had:
Darkened skin that resolved within 24 hours
Severe, hemorrhage, necrosis, and inflammation that increased for at least 96 hours
Conclusions: IM enrofloxacin in striped bass causes tissue necrosis.
Describe pharmacokinetics of danofloxacin when administered 10 mg/kg IM in koi.
How does this differ from enrofloxacin?
Pharmacokinetics of danofloxacin following intramuscular administration of a single dose in koi (Cyprinus carpio)
Christine A. Parker-Graham, Wesley C. Siniard, Barbara A. Byrne, Heather K. Knych, Esteban Soto
(Am J Vet Res 2020;81:708–713)
Introduction:
Danofloxacin = broad spectrum (Gram +, -, Mycoplasma), bactericidal, concentration-dependent fluoroquinolone
MOA: Inhibits bacterial DNA gyrase
Key Points:
IM danofloxacin at 10 mg/kg was rapidly absorbed (detected within 15 min)
Above MIC90 for common bacteria (Vibrio, Pseudomonas, Aeromonas) for at least 96 h post-injection
No inflammation or myodegeneration at injection sites
Conclusions: Danofloxacin 10 mg/kg IM in koi is rapidly absorbed (15 min), above MIC90 for >96 hrs (4d), and has no injection site reactions.
How can mortalities during copper treatment be reduced?
Retrospective review of copper sulfate immersion treatment in marine teleosts during quarantine at the National Aquarium of Baltimore from 2004 to 2016.
Zec S, Hadfield C, Hungerford L.
Journal of Zoo and Wildlife Medicine. 2021 Apr;52(1):97-102.
FW system - Copper tx based on alkalinity (low alkalinity more toxic copper).
SW system - Ionic form Cu2+ is active, dependent on alkalinity, pH, salinity.
Tx is generally slowly increased over 3-5 days, maintained for 21 days, and then removed with activated carbon and water changes.
This study recommended slowly increasing copper over 7 days and starting 1 wk after fish have been in quarantine to reduce mortality.
Overall 4% mortality rate, but some species were more susceptible. Mortality was more likely to occur in the subtherapeutic period.
System volume did not have an impact
Still recommend copper treatment over introducing C. irritans
How did vertebral lesions for discus receiving a beef heart diet compare to commercial discus feed?
Lewisch, E., Gumpenberger, M., Amesberger-Freitag, A., & El-Matbouli, M. (2018). Preliminary radiographic observations of vertebral changes in discus (symphysodon discus). Journal of Zoo and Wildlife Medicine, 49(4), 1016-1020.
- Beef heart, low water calcium group and commercial food, moderate water calcium group had the most vertebral alterations, but alterations were seen in all groups including controls.
- May suggest the unbalanced diets have aggravated an underlying condition.
Takeaway: Unsupplemented beef-heart diet not appropriate for discus, but commercial discus feed did not appear much better. Overall further nutritional investigations needed for this and other commonly kept fish spp.
How does tumor type affect cryotherapy effectiveness in cutaneous neoplasms of fish?
LIQUID NITROGEN CRYOSURGERY FOR CUTANEOUS AND OCULAR NEOPLASMS IN KOI (CYPRINUS CARPIO) AND GOLDFISH (CARASSIUS AURATUS): EIGHT CASES (2018–2019)
Journal of Zoo and Wildlife Medicine 52(2): 763–773, 2021
This report suggests that the use of cryosurgery for the treatment of cutaneous tumors may be curative for certain sarcomas, but appears to be ineffective in case of melanophoroma
· Besides tumor type, the response to treatment and prognosis appears to be heavily dependent on the progression or stage of the neoplasm at the time of diagnosis (ie depth of invasiveness and completeness of surgical margins)
· Tumors appeared to become MORE invasive when they recurred after cryotherapy, causes of this is unknown
· Cutaneous and corneal tumors, despite their similar histologic appearance, respond differently to cryotherapy
What was observed at the IM injection site following injection of meloxicam in goldfish? How did this compare to saline control?
Larouche, C. B., Limoges, M. J., & Lair, S. (2018). Absence of acute toxicity of a single intramuscular injection of meloxicam in goldfish (carassius auratus auratus): a randomized controlled trial. Journal of Zoo and Wildlife Medicine, 49(3), 617-622.
Key Points:
• Meloxicam – preferential COX-2 selective NSAID
• PK study in Nile tilapia showed 1 mg/kg only lasts for 4-6 hours
• This study
• Gave 5 mg/kg (1 mL/kg) meloxicam or 1 mL/kg saline
• Necropsy – no obvious signs of toxicity, various other pathologies identified
• Significant IM hemorrhage at injection site for both
Take home: Meloxicam 5 mg/kg produces local muscle necrosis but so does IM injection of saline and acute toxicity otherwise was not observed.
What is the causative agent of bacterial kidney disease?
Richards, C. A., Abdel-Latif, H. M., Loch, T. P., & Faisal, M. (2021). High prevalence of circulating antibodies to renibacterium salmoninarum in spawning oncorhynchus spp. from lake michigan, usa. Journal of Wildlife Diseases, 57(1), 19-26.
- Renibacterium salmoninarum – Causative agent of bacterial kidney disease BKD.
o Salmonids, FW and SW. Wild, feral, and farmed in Great Lakes Basin.
o BKD prevalence declined in trout following implementation of strict biosecurity measures in egg collection facilities and culling of infected fish. Still high in other salmonids.
Takeaways: High number of seropositive Oncorhynchus spp means R. salmoninarum still prevalent in Lake Michigan and continues to constitute a potential risk for other nonmanaged susceptible salmonids likely exposed. Modified Ab ELISA useful tool for screening seropositive salmonids. Chinook salmon > steelhead trout > Coho salmon.
How did immersion in MS222, 2PE, and clove oil impact anesthesia and cessation of physiologic measures (caudal fin stroke, reaction to stimuli, righting reflex, swimming, operculation) and HR in cichlids?
What was the most economically viable option? Which was most expensive?
Bradley, S., Sparrow, S., Rowden, L. J., & Guthrie, A. (2021). USE OF TRICAINE METHANESULFONATE, CLOVE OIL AND 2-PHENOXYETHANOL FOR IMMERSION EUTHANASIA OF UNGA CICHLIDS (SAROTHERODON LINELLII). Journal of Zoo and Wildlife Medicine, 52(3), 893-900.
After a 60-min immersion in the euthanasia solution, the presence of an audible heartbeat was identified in 100% of the cichlids immersed in 2-PE, 100% immersed in CO, and 90% in MS-222, indicating that they were not reliably euthanized. Therefore, a two-step protocol is recommended in cichlids for euthanasia: heavy anesthesia via immersion followed by an intravenous or intracardiac injection of euthanasia solution, or other secondary method of euthanasia.
The cost of euthanasia per cichlid was calculated, with the most economically viable option being 2-PE; MS-222 was the most expensive.
Time to all CPM significantly longer in 2PE vs MS-222.
IV injection of pentobarb was required in 97% to ensure HR stopped.
Which organ was most contrast enhancing on contrast CT of koi?
How did the delayed parenchymal phase compare to the timeline in mammals?
Brust, K., Phillips, K., Kaufman, M., Stevens, B., Camus, A., Camus, M. S., & Soto, E. (2021). INTRAVENOUS CONTRAST-ENHANCED COMPUTED TOMOGRAPHY IN ADULT KOI (CYPRINUS CARPIO). Journal of Zoo and Wildlife Medicine, 52(2), 460-469.
The caudal kidney was the most contrast-enhancing organ. Both doses produced good vascular enhancement and similar distribution. The delayed postcontrast scans showed repeatable parenchymal enhancement of organs. No mortality was encountered. No abnormalities were detected on blood smears, necropsies, or histopathology. Results suggest IV contrast administration is feasible, both contrast doses provided valuable anatomical information in the study with CT of coelomic organs, and no contraindications of contrast administration were detected.
o Initial vascular phase, delayed parenchymal phase (similar to mammals but was slower overall – 5 min later). Fish have lower BP.
o Caudal kidney most strongly contrast-enhancing organ.
o Spleen only organ not readily identified as separate from adjacent liver parenchyma.
- Ecchymosis at the injection site in some fish 24h after injection, no other side effects.
Describe a nociceptive model that could be used in fish?
Journal of Zoo and Wildlife Medicine 52(2): 529-537, 2021
PHARMACOKINETIC, PHARMACODYNAMIC, AND TOXICOLOGY STUDY OF ROBENACOXIB IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)
Juliette Raulic, Dr méd vet, IPSAV, Francis Beaudry, PhD, Guy Beauchamp, PhD…
• Used previous nociception models in rainbow trout - intralabial acetic acid injection causes lip rubbing, rocking, increased opercular rate; hyporexia is also reliable pain indicator in postoperative koi
- PK study: 6 trout robenacoxib 2 mg/kg IM, venipuncture at 5 timepoints up to 72h post; 2 controls given saline
- Analgesic concentrations (10 ng/mL, based on cats) measured for 3-4d in trout kept at 12°C with average Cmax of 2.1h postinjection
- PD study: 10 trout injected w/ intralabial acetic acid, 6 treated w/ robenacoxib, 4 controls given saline
- Significant decrease in rocking behavior in robenacoxib fish.
- No difference in opercular frequency; could not analyze rubbing behavior (infrequent)
Take-Home Message: Robenacoxib 2 mg/kg IM may give 3-4 days of analgesia in rainbow trout. No adverse effects of histopathologic lesions seen with this drug but difficult to monitor antemortem renal lesions in fish
Describe evidence-based treatment of lateral line depigmentation of individual fish.
What are four broad categories of causes of LLD?
AN INTEGRATIVE REVIEW OF LATERAL LINE DEPIGMENTATION IN MARINE AND FRESHWATER FISH Dannemiller, O’connor, Van Bonn; JAVMA
Infectious agents (least likely): diplomonad flagellates (Spironucleus) and reovirus-like agent from angelfish; Aeromonas hydrophila isolated from one fish • May be secondary invaders
Water quality:
• Poor water quality—groundwater pools
• Heavy metals likely most causative factor (copper, zinc, cadmium) and damaged skin of mummichog
• Low pH and high CO2 could also be a potential factor
Nutrition:
• Vitamin deficiency (especially tangs and surgeonfish)
• Blue tangs fed dry flake diet developed LLD after 3 weeks, but animals fed the same but grazed were unaffected.
- Resolved when fed green algae supplemented with vitamin C.
- Low vitamin A may cause HLLE in captive tangs
Activated carbon:
• Activated carbon filtered in led to LLD in tangs in 2 studies, typically in 14 days
• Severity varied among investigations
CONCLUSIONS AND CLINICAL RELEVANCE LLD should be considered a clinical observation indicative of a dermatologic response of fish to suboptimal conditions; LLD should continue to be adopted as the preferred term to describe the classic signs. Whereas gross findings are similar among species, histologic findings can vary.
Evidence-based treatment of LLD for individual fish consists of source control (changing tanks or systems), topical treatment with 0.01% becaplermin gel, supportive care, and antimicrobial treatment when warranted. For schools of fish, treatment and prevention of LLD should be focused on improving suboptimal environmental and physiologic conditions.
Meloxicam PK in tilapia?
PHARMACOKINETIC EVALUATION OF MELOXICAM AFTER INTRAVENOUS AND INTRAMUSCULAR ADMINISTRATION IN NILE TILAPIA (OREOCHROMIS NILOTICUS)
Daniel V. Fredholm, Natalie D. Mylniczenko, Butch KuKanich
J. of Zoo and Wildlife Medicine, 47(3):736-742 (2016).
Take Home Message: Meloxicam 1mg/kg IM or IVgiven to Nile tilapia leads to appropriate Cmax but a very short half-life short, requiring q4-6h dosing interval. Bioavailability of IM half that of IV.
Name 3 cyprinid herpesviruses
What family are fish herpesviruses in?
Alloherpesviridae
CyHV1 – “Carp Pox”
- Epidermal hyperplasia, cosmetic
CyHV2 – Goldfish Herpesvirual Hematopoetic Necrosis Virus
- Targets anterior kidney. Juvenile goldfish, high mortality.
CyHV3 – Koi Herpesvirus; REPORTABLE
- All ages, high mortality. Goldfish and grass carp asymptomatic.
- Targets gills.
- Permissive temp 23-28 C (60-82F). Incubation 7-21 days, so hold fish at permissive temp at least 4 wks in quarantine.
- Test ELISA or VN for antibodies, persiste for years. PCR gill, kidney, spleen. Cell culture kidney, spleen.
What type of virus is Spring Viremia of Carp Virus?
When are outbreaks?
Dx?
Response to active outbreak?
How can you declare a population virus free?
Spring Viremia of Carp Virus* OIE
Rhabdovirus carpio (carp spivivirus RNA)
Outbreaks in winter - Hemorrhages of skin/organs, edema, ascites, bloody mucoid discharge from vent.
Immunosuppression is triggered by the cold - Peak mortality 15-17C, most fish survive > 20 C.
Dx - Viral isolation (spleen, caudal kidney), viral neut, PCR
Pos results from IF, ELISA sufficient to initiate control measures
Active outbreak – Depopulation; mandatory (unlike KHV).
Inactivation:
Formalin, ozone, sodium hypochlorite, organic iodophors, gamma and UV radiation, pH extremes (<4 or >10)
Heating at 60C for 15 minutes
Incoming water should be treated with sand filtration and UV
To declare virus free:
Test negative for at least 2 years
Water supply only from spring, well, or borehole free of wild fish
Incoming water should not be connected to a watercourse, or natural barrier should prevent upstream migration of fish
Which cyprinid herpesvirus is reportable to the OIE?
Which other cyprinid virus is reportable to the OIE?
Cyprinid herpes 3 (koi herpes)
Spring viremia of carp virus (rhabdovirus/spivivirus)
What are your quarantine recommendations for a koi hobbyist interested in adding three new koi to their established koi pond?
Minimum 4-6 weeks at permissive temp for KHV (18-28C or 60-82F)
Consider serology to aid in detection of carrier fish
Avoid mixing susceptible species (goldfish, grass carp carriers)
Consider source/disease free fish
Baseline diagnostics (skin/gill biopsy), general health assessment
What type of parasite is amyloodinium? Life cycle? Tx?
Amyloodiniosis aka Marine Velvet Dz (SW)
Warm water marine fish and elasmos
Dinoflagellate
Trophont (lesions on fish) -> tomont (free swim) -> dinospores (floating spores that enter new host); LC can be completed in 3-6 days.
Division limited to 61-86F but can return to dividing when warms up even after 4 mos
Tx copper, chloroquine diphosphate, FW; (formalin resistant)
What type of virus is red seabream iridovirus? Is this virus reportable?
Red seabream iridovirus:
Megalocytivirus, family iridoviridae
Characterized by presence of cytomegalic inclusion body bearing cells IBCs, often occupy entire cell cytoplasms, typically in spleen but can be systemic
RSIV is reportable to the OIE
What is the causative agent of whirling dz in hartchery-reared salmonids?
Myxobolus cerebralis
Myxozoan parasite, whirling dz
Requires oligochaete worm Tubifex tubifex and salmonid host to complete LC
Life cycle of ichthyopthirius multifilis?
Trophont (feeds on fish) -> tomont (encysts onto substrate, divides) -> theront (fish-infective stage)
Describe how pH, temp, salinity influence % ionized vs unionized ammonia
o Primary protein waste product from fish is ammonia
o Passively excreted across gills, lesser extent in urine and feces
o Two forms:
- Ionized ammonium NH4+
- Unionized ammonia NH3 – 100x more toxic to fish
o As pH and temp increase and salinity decreases, greater percentage becomes unionized and more toxic
(fresh, basic, hot water = toxicity)
Describe how temp and salinity affects dissolved oxygen
Higher temp = Lower DO
SW holds less O2 vs FW at the same temp
Higher temp, SW = lower total O2 dissolved in water
Cold, FW = highest total O2 dissolved in water
Cold freshwater has high oxygen
Describe two methods for measuring ammonia and compare/contrast
Ammonia assays
- Spectrophotometer
Preferred – ammonia salicylate test
• No false reactions with SW
• No interference caused by ammonia-locking compounds – chemical ammonia binders on market
- Nessler method
• Requires complexing minerals (esp magnesium in SW)
• Sensitivity is decreased ~30% in SW due to chloride ions
• Reagent contains mercury and hazardous waste
Describe relationship between alkalinity and copper toxicity
Copper sulfate tx is contraindicated in low alkalinity because of the possibility of rapid pH changes (generally an issue in FW systems).
How can nitrite toxicity be prevented in Channel Catfish?
Cl competitively inhibits nitrite uptake across gill; maintain at low level of salt
Nitrite toxicity is a FW fish thing - 1 ppt SW contains over 500 mg/L chloride, prevents toxicity
Describe water quality parameter changes in pond over the course of the day
DAWN - Low O2, high CO2, low pH; Over course of day, photosynthesis uses CO2/produces O2, results in increase in pH and dissolved O2
DUSK - High DO, high pH, low CO2
Chronically high diurnal pH in ponds almost always caused by excessive phytoplankton or photosynthesis as CO2 is consumed
List OIE reportable viral fish diseases (8)
Koi herpes (cyprinid herpes 3)
Spring viremia of carp (rhabdovirus)
Viral hemorrhagic septicemia virus (rhabdovirus)
Infectious hematopoietic necrosis (rhabdovirus)
Epizootic hematopoietic necrosis (iridovirus/ranavirus)
Red seabream iridivorus
Infectious salmon anemia (orthomyxoviridae)
Salmonid alphavirus (togaviridae)
What is the causative agent of furunculosis in salmonids and what treatments are approved by the FDA?
Aeromonas salmonicida subsp. salmonicida
- Nonmotile, gram neg
Oxytetracycline dihydrate (Terramycin 200), sulfadimethoxine and ormetoprim (Romet 30), Florfenicol (Aquaflor) PO
What drug is FDA approved for tx of motile aeromonad septicemia in catfish and salmonids?
Aeromonas hydrophila and friends
Oxytetracycline PO
What is the causative agent of enteric septicemia of catfish?
Edwardsiella ictaluri
Causes economic losses of channel catfish (Ictalurus punctatus)
Acute enteric form, chronic neurologic form
Sulfadimethoxine and ormetoprim, florfenicol PO approved
Describe the integumentary anatomy of teleosts.
What is the outermost layer? What is its function?
What cells make up the epidermis? Is the epidermis keratinized?
Describe the anatomy of the dermis.
How can chromatophores be used to localize lesions?
What are the various scale types in teleosts? Which are teh most common?
What fish are scaleless? What have very fine scales? How does being scaleless affect a fish?
What fish taxa produce excessive mucous?
What is the lateral line?
What fish have bacterial luminescence?
Integument
- External mucus layer
- Rich in mucopolysaccharides, immunoglobulins, lysozymes, free fatty acids 🡪 mucosal defense system
- Epidermis = epithelial cells, mucous glands
- Thicker in fish w/ no scales
- Unlike mammals - lacks keratin, all layers capable of mitosis (including squamous)
- Dermis = scales, chromatophores, mast cells
- Chromatophores - color change can imply different physiologic states
- Generalized dark color - stress, disease
- If only on one side - may indicate visual problem
- If only caudal, may localize spinal problem
- Scales embedded w/in pockets of dermal tissue, oriented toward tail
- Scale types - placoid, cosmoid, ganoid, cycloid, ctenoid
- Cycloid, ctenoid most common in teleosts
- Some large & thick like ganoid scales of arowana/arapaima/sturgeon/tarpon
- Avoid puncturing w/ needles - removal of scale can lead to osmoregulatory problems, infection (esp. 2º like oomycetes, scuticociliates)
- For surgery - can remove along incision
- Some have very fine scales (jacks, tuna), others scaleless (jacks, eels, catfish, elephantfish)
- Scaleless - may be more vulnerable to toxins, medications, direct trauma
- Some have deciduous scales & shed regularly (herring, anchovies)
- Scale types - placoid, cosmoid, ganoid, cycloid, ctenoid
- Some have segmented bony plates w/in dermis (seahorses, pipefish, shrimpfish, trunkfish, boxfish, armored catfish, Plecostomus)
- Injection, incision in soft areas; if must be cut - seal w/ wax
- Pufferfish - erectable spines from scales w/ overlapping roots - must be cut for coelomic incision
- Chromatophores - color change can imply different physiologic states
- Some produce copious mucus - eels, catfish, rays
- Slippery, use chamois or flannel cloth to help
- Parrotfish create mucoid casting (cocoon) at night - hand-net catches easier at night
- Epithelial hyperplasia - common, nonspecific response to irritants; can be MF
- Some fancy goldfish - overgrowth of head epithelium (wen, hoof) - consists of non-ciliated epithelium w/ goblet cells covering mucinous stroma
- Lateral line - canal w/in integument w/ pores - in canal are neuromasts w/ sensory hairs surrounded by gel material 🡪sensitive to water displacement and vibration
- Depigmentation common problem
- Transparency feature in some - d/t arrangement of collagen fibers allowing passage of light (glass catfish)
- Bacterial luminescence - Beryciformes group (pinecone fish, flashlight fish)
- Have single species of bioluminescent bacteria (Photobacterium fischeri) in organ under eye
- Bacteria may be observed by pulling into or covering w/ fold of skin
- Antibacterial Tx can damage the bioluminescent bacteria
Integumentary system (ZP)
- Epidermis, dermis, and hypodermis.
- Epidermis lacks keratinization except the reproductive tubercles of male cyprinids.
- Outer layer of goblet cell mucus and protoplasma aka glycocaylx or cuticle contains immunoglobulins, lysozyme, and antipathogen effector molecules for defense.
- Alarm or club cells present in Cypriniformes, Characiformes, Gymnotiformes, Siluriformes.
- Dermis divided into vascularized stratum spongiosum and dense stratum compactum.
- Also contains scales, chromatophores, and lateral line system.
- Scale loss represents a true ulcer and potential for microbial invasion.
- Cycloid scales – Salmonids, cyprinids; oval.
- Ctenoid scales – Spiny fish i.e. perchids; posterior spines (ctenii) and anterior radii directed from a central focus.
- Hypodermis composed of connective tissue and adipose.
What is the primary function of the teleost swim bladder? Are there any secondary funcitons?
What is the gas composed of?
What are the two types and list some taxa that have each?
What fish have one lobe? What about 2? What about 3?
Which have swim bladders that extend down the vertebrae?
Which are modified into lung-like tissue?
Buoyancy Organs
● Swim (gas) bladder - extensive spp. variations
● 1º function - buoyancy; but also sound production, pressure reception
● Absent in cartilaginous fish, some bottom-dwelling teleosts, weather loaches, some highly pelagic teleosts
● Filled w/ oil or fat in some bathypelagic spp. (laternfish, orange roughy)
● Volume to BW typically <5% in SW and <7% in FW
● Gas composed of CO2, O2, N - not in same %s as air
● Types of swim bladders -
o Physostomous - pneumatic duct connect swim bladder to esophagus; gas maintained by swallowing air (FB or gavaged food can enter swim bladder); some have rete mirabile for some gas absorption
▪ Salmon, trout, catfish, koi, goldfish, tetras
o Physoclistous - lack connecting duct; inflation via blood gases diffusion along one or more rete mirabile (gas glands) or vessels (typ. cranial and ventral); some also have capillary plexus caudodorsally (oval or oval window) to help resorb gases
▪ Most marine teleosts, cichlids, bass, sunfish
● Must know normal swim bladder appearance d/t species differences
o Abnormalities - hyperinflation, hypoinflation, displacement, fluid, parasites
o One lobe - most common - may be U-shaped (some pufferfish)
o Two lobes in several spp. (goldfish, carp, koi - some goldfish breeds lost Cd. lobe)
o Three lobes - cod, channel catfish, some pufferfish
o Extension common - may connect to inner ear (herring, anchovies), extend into vertebrae (FW angelfish), extend down the tail (electric eel, arowana)
o May be modified into lungs/lung-like tissues (garfish, tarpon, arapaima, lungfish)
Describe the respiratory anatomy of teleost fish.
What makes up the gill arch, filaments, and lamellae?
What is the function of gill rakers?
What is the function of the pseudobranch? What are the three types of pseudobranchs?
What fish are obligate air breathers?
What are some facultative air breathers?
Respiratory System
- Not inspiration/expiration 🡪 continuous flow; rate determined by muscular/opercular pumping
- Gills primary organ in most fish - covered by operculum or skin w/ slits
- Two sets made up of gill arches (holobranchs)w/ paired rows of 1º gill filaments (hemobranchs)
- Each 1º filament has perpendicular 2º filaments
- Most bony fish have 4 gill arches; uniform dark red (pink to white w/ anemia, fades after death, brown w/ methemoglobinemia)
- Some have gill rakers - sieve to collect food
- Gill epithelium thin to allow gas exchange - but also vulnerable to pathogens, toxins
- Have metabolic, excretory functions - damage can subject o respiratory and osmoregulatory challenges
- Have some capacity to regenerate (w/in 1-2 wks after insult then ~2 wk growth)
- Bilateral pseudobranchs - dorsocranial to gill arches in most (except catfish, some eels, African knifefish, spiny loaches)
- 3 types - free (exposed - look like partial gill arch, direct contact w/ water - some perch-like fish, many marine spp.), covered (w/ subtypes - resemble gill arch but have membrane covering -cyprinids, salmonids), glandular (deep w/in connective tissue - some gouramis, snakeheads, featherbacks)
- Delivers O2 to choroid of eye via carbonic anhydrase pathway, suspected of regulating intraocular O2 and pressure - depends on hydrostatic and osmotic pressure, pH, pCO2
- Some also deliver O2 to vascular rete of swim bladder
- Proposed osmoregulatory and glandular function not understood
- Surgery (removal, ablation, cautery) when ocular gas nonresponsive to medical management
- Most have opercula - appearance varies; sturgeon doesn’t completely cover gill, marine angelfish - spike
- Opercular flaring - egg incubation temps, genetics, trauma, nutritional issues
- Consequences vary from cosmetic to gill damage
- Some lack opercula (triggerfish, eels, frogfish, lumpfish, seahorses, sea dragons, pipefish)
- Opercular flaring - egg incubation temps, genetics, trauma, nutritional issues
- Use pressure change to move water over gills; some swim to do this (must ventilate these under manual or chemical restraint!)
- Air-breathing can occur - if low DO or survive brief periods out of water
- Obligate air-breathers
- Rudimentary gills, do not do enough gas exchange over gills for respiration, so if air access restricted unable to ventilate
- Gourami, betta, snakeheads (labyrinth organ), African reedfish, arapaima, non-Australian lungfish (lung), African knifefish, FW butterflyfish (swim bladder), electric eel, mudskippers, swamp eel (pharynx), mudskippers (skin), weather loach (intestine)
- Obligate air-breathers
- Facultative air-breathers
- Maintain gas exchange across gills and use air when DO is low
- Australian lungfish (lung), arowana, Atlantic tarpon, gar, various catfish (swim bladder), Alaska blackfish (esophagus), various catfish (GI tract, labyrinth organ)
- Organs can include buccal/pharyngeal cavity surface, GI tract, swim bladder, lungs
- Skin respiratory in many fish, including larval stages - directly observed
- Many FW teleosts able to do aquatic surface respiration (ASR) - when DO is low - surface to skim air/water interface d/t higher DO content
● Respiratory system
- Gills – respiration, osmoregulation, excretion.
- Respiratory efficiency complicated by higher density of water, lower availability of DO, variable osmolality of aquatic environments.
- Four pairs of bony arches extend from roof to floor of pharynx.
- Two diverging rows of filaments extend posteriorly and laterally.
- From filaments, plate-like lamellae (site of gas exchange).
- Oriented parallel to flow of water.
- Pseudobranch – High in carbonic anhydrase, believed to increase O2 delivery to retina via choroid rete.
Describe the reproductive anatomy of teleost fish.
What forms of hermaphroditism are common?
What is the term for sequential hermaphroditism where males become females? What species exhibit this?
What is the term for sequential hermaphroditism where females become males? What species exhibit that?
What are the two basic ovarian arrangements? How big are the ovaries?
What is the functional unit of the testis? What are the three varietis of spermatogenic organization in teleosts?
Is fertilization external or internal?
Where do livebearing fish develop?
What are some of the reproductive modalities of bony fish?
Reproductive System
- Highly variable, complex; typically separate sexes but hermaphroditism, parthenogenesis occur
- Hermaphroditism esp. common w/in Perciformes (parrotfish, wrasses, damsels, gobies)
- Protandry (sequential; males become females) - gilthead seabream, clownfish
- Protogyny (sequential; females become males) - Indo-Pacific cleaner wrasse
- Simultaneous hermaphroditism - can release viable eggs or sperm in same spawning - hamlets
- Parthenogenesis - less common but happens (Amazon mollies - all female)
- Hermaphroditism esp. common w/in Perciformes (parrotfish, wrasses, damsels, gobies)
- Some show sexual dimorphism and some assoc. skin changes can be mistaken for pathology
- Testis - typ. elongated, paired, lobular (common) or tubular;
- Assoc. connective mesorchium; surrounded by tunica albuginea
- Can look like ovaries in young fish 🡪 wet mount to differentiate
- Ducts can both store and transport sperm
- Ovaries - vary from cultures of follicles to organized organs (paired, fused, or coiled)
- Assoc. connective mesovarium
- Mature ovaries can take up to 70% of the coelom
- Typ. paired - fused in some spp. (lampreys, hagfish, mollies, guppies, medaka)
- Types of ovaries
- Cystovarian - ova released into oviduct; (most bony fish, gar)
- Gymnovarian - ova released into coelom 🡪 ostium 🡪 oviduct (lungfish, sturgeon, bowfin, cartilaginous fish)
- Semicystovarian (2º gymnovarian) - ova released into coelom 🡪 urogenital pore (salmonids)
- Live-bearing species - embryos develop in either oviduct or the uterus
- Fertilization can be internal or external
- Reproductive system
- Gonads, efferent ducts (oviduct or ductus deferens), genital papilla.
- Two basic ovarian arrangements – Cystovarian, gymnovarian.
- Most are cystovarian – eggs released into central ovarian cavity contiguous with the oviduct.
- Some spp, eggs release into coelomic cavity and are expressed through an elongated or short oviduct segment.
- Functional unit of ovary is the follicle.
- Oocyte surrounded by sheaths of theca and granulosa cells.
- Primordial germ cells/oogonia -> ovarian germ cells (oocytes/follicles) -> ovulation -> post-ovulatory follicle, rapidly resorbed by resident macrophages.
- Synchronous spawners – all eggs spawned simultaneously.
- Female dies or spawns again next year.
- Asynchronous spawners – Spawn multiple times, only expel some follicles at each cycle, different folliculogenic phases may be evident continuously.
- Most are cystovarian – eggs released into central ovarian cavity contiguous with the oviduct.
- Functional germinative unit of testis – spermatocyst.
- Three major varieties of spermatogenic organization – Tubular, unrestricted spermatogonial, restricted spermatogonial.
- Tubular – Spermatocysts develop throughout entire length of each seminiferous tubule.
- Unrestricted spermatogonial – Most common, lobules originate blindly at periphery of testis.
- Restricted – Spermatocysts initially form only at blind ends of tubules at periphery of testis, maturation progressive within spermatocysts as they migrate toward a central duct to be expelled.
- Male germ cells become smaller as they occur.
- Three major varieties of spermatogenic organization – Tubular, unrestricted spermatogonial, restricted spermatogonial.
Discuss antibiotic resistance in public aquaria.
What is the difference between innate and acquired antimicrobial resistance?
What are these standard definitions for antimicrobial resistance?
- Multidrug resistant
- Extensively drug resistant
- Pandrug resistant
How does assessing resistance differ between a clinical and an epidemiological standpoint?
Describe the public aquaria AMR cycle
- How does chlorination affect AMD?
- How does UV affect AMD?
- How does ozone affect AMD?
- How can AMR elements be introduced into aquarium systems?
What are the four classes of drugs based on the European Medicine’s Agency of AMR?
What are some of the common bacterial pathogens affecting taxa in public aquaria?
- Which are the most resistant?
- What antibiotics show the most promise for use?
- How does it vary by taxa - fish, amphibians, birds?
Antibiotic Resistance in Public Aquariums
Fowler 10 Ch. 59
Resistance Mechanisms
* Despite different mechanisms of action, all AMD (antimicrobial drug) classes have strains with AMR (antimicrobial resistance)
* Innate AMR, distinctive in a species or genus, is a slow adaptive evolutionary process in response to environmental pressure
* Acquired AMR is a quick adaptive process to an abrupt selective AMD pressure
* Mutation in the bacteria’s genome or acquisition of foreign DNA material encoding AMR-resistant genes through horizontal gene transfer are the two main genetic strategies for a bacterium to gain AMR
Multidrug Resistance Organisms
* Multiple drug resistance (MDR) occurs in multidrug-resistant organisms that show in vitro resistance to more than one AMD
* Extensively drug resistant - at least one agent in all but one or two antimicrobial classes
* Pandrug resistance - nonsucuscebtility to all agents in all antimicrobial categories
Testing
* Veterinary AMD prescriptions should be backed by antimicrobial susceptibility tests (AST)
– The most common methods for these ASTs are disk diffusion and minimum inhibitory concentration (MIC) tests
– The reliability of disc diffusion test results decreases at lower incubation temperature, so MIC, performed by broth dilution, is preferable in cultures done at less than 28°C
* In a clinical perspective, a bacterial clinical breakpoint is the MIC or disc zone size value utilized to classify a bacterial strain as susceptible, intermediate, nonsusceptible, or resistant
– These definitions are established by breakpoints which are based on AST values for the isolate, in the AMD pharmacokinetics and pharmacodynamics (PK/PD) in the animal species, and in the clinical outcome based on previous data, so they are pathogen, AMD dose, and host-specific
- An epidemiological perspective will be centered on the distribution of susceptibility to an AMD from different isolates of a specific bacteria species, regardless of the animal species affected
– These definitions use epidemiological cut-off values (ECOFFs=ECV), which define bacteria species, using statistically determined MIC or disc diffusion values, as wild type (WT), as opposite to nonwild type (NWT), by the absence of acquired and mutational mechanisms of resistance to a specific AMD
- Few ECVs are determined for bacteria isolated from aquatic animals (e.g., A. salmonicida, A. hydrophila, Flavobacterium columnare, F. psychrophilum, and Edwardsiella ictaluri)
Antimicrobial Stewardship
- The European Medicines Agency’s (EMA) Antimicrobial Advice ad hoc Expert Group (AMEG) divided AMD classes (and subclasses) into four categories, taking into consideration if they are licensed for veterinary use in the European Union, importance to human medicine according to World Health Organization (WHO), the possibility of transferring AMR from animals to humans, and availability of other veterinary antibiotics with lower AMR risk
Public Aquarium Antimicrobial Resistance Cycle
* Water supply (e.g., municipal/tap water and seawater) may be a source of resistant elements, and to mitigate this biological contamination, water may be treated (e.g., ozone or ultraviolets [UVs]) before being in contact with the animals
– Water treatments and disinfection methods (WTDM) commonly used in public aquariums (e.g., activated carbon, chlorination, UV, or ozone) will significantly decrease the presence of ARBs, ARGs, and AMD residues
– Chlorination eliminates AMD as ampicillin, tetracycline, cephalexin, and cefotaxime
– Macrolides are poorly removed by UV, while flumequine is effectively removed by UV/ H2 O2 or by activated carbon fixed-bed columns
– Ozone may significantly reduce ofloxacin, trimethoprim, sulfamethoxazole, sulfapyridine, and clarithromycin levels
* Wild animals, even from pristine ecosystems, may also harbor ARBs/ARGs
* Food may also carry resistant elements in live animals, raw fish feed, dry pelleted food, and in vegetables
* The risk of staff being a source of ARBs and ARGs for the animal collection, and vice versa, could be mitigated by biosecurity measures (e.g., footbaths, handwashing, and disinfection protocols, general disinfection protocols, wearing working clothes and shoes, baths prior to and after diving, etc.) which may also be applied to public interactions with animals (e.g., touch pools and diving with animals).
* Routine bacterial cultures and ASTs should be part of the diagnostic testing performed under the health control program
A recent study investigated the efficacy of acyclovir against cyprinid herpesvirus 3 infection in Koi.
What is the scientific name of this species?
Describe koi herpes viral disease
- What is the temperature range of this disease?
- What role do latent infections play?
- What are the clinical signs?
- How is this disease managed?
What is the mechanism of acyclovir?
- How has it been used in this disease in the past
- What pharmacokinetic data is available in this species?
What was this study design?
- What clinical signs were seen in this study?
- Was there a difference in survival?
- What was a potential additional cause of mortality in this study?
Efficacy of a multidose acyclovir protocol against cyprinid herpesvirus 3 infection in koi (Cyprinus carpio)
AJVR 2022 - Mariana Sosa-Higareda, ONE DACVM
OBJECTIVE To evaluate the effect of a multidose acyclovir protocol on koi herpesvirus (KHV) viral load and mortality in a cohabitation challenge.
ANIMALS 180 koi fish.
PROCEDURES Forty fish (shedders) were immersed in a 0.5 KHV plaque-forming units/mL static bath for 8 hours. Mock shedders were treated similarly but exposed to cell culture media. KHV shedders were then transferred into 8 tanks (5 shedders per tank) containing 10 naïve fish (cohabitants) each.** Fish in the acyclovir group (AT) received a 10 mg/kg acyclovir intracoelomic injection 1, 3, and 6 days after the first confirmed KHV mortality**. Positive controls (PC) were treated similarly but received sterile saline injections. Negative controls (NC) were exposed to mock shedders. Morbidity and mortality were evaluated daily for 50 days post-challenge. Quantitative PCR was used to determine viral load in the gill biopsies of shedders and cohabitants collected at days 19 (T1), 22 (T2), 25 (T3), 34 (T4), and 50 (T5) post-challenge.
RESULTS Survival curves analyzed by the Gehan-Breslow-Wilcoxon method revealed a delayed onset of mortalities and a significantly lower KHV load at T2 and T3 detected in AT cohabitant fish (P = .042) compared to positive control group. However, there were no significant differences in overall mortality or viral loads at T5.
CLINICAL RELEVANCE The acyclovir protocol used in this study did not control viral infection or mortality at the end of the 50-day trial. Shorter intervals between injections could improve outcomes, but the additional stress inflicted by handling should be considered. Exploring other therapeutic alternatives and doses is warranted.
Basics:
- KHVD – temperature dependent = disease between 16-28 degrees C
- Latency infections: Stress 🡪 viral replication and shedding 🡪 outbreaks
- CS: nonspecific and include lethargy, hyporexia, pale and necrotic gills, enophthalmos, reduced skin mucous production sometimes leading to sandpaper texture, and ulcerative hemorrhagic skin lesions
- Strict biosecurity is only method of prevention and there is no effective treatment
- Temp manipulation and prolonged salting can disrupt replication and provide palliative tx
- Acyclovir = synthetic 20-deoxyguanosine (guanine) nucleoside analog capable of selectively inhibiting the activity of viral DNA polymerase, thus preventing viral replication
– Reported to decrease KHV cytopathic effects, viral load, and viral gene expression in vitro using common carp brain cells
– PK study – 10 mg/kg in koi fingerlings reached MIC for >24 hrs
–Reduction in mortality and showed safety via ICe route
Details:
- Clinical signs and gross changes in KHV-infected fish were evident in shedders and cohabitants and included anorexia, lethargy, hemorrhagic and ulcerative skin lesions, hyphema, exophthalmia, and pale gills
- highest number of mortalities occurred at days 25 for + control and 36 postexposure in treated groups
- No significant difference in survival between groups results suggest that there is a positive effect on survivability while receiving acyclovir
effect decreases with time after the last dose
- frequently repeated administration is required to achieve adequate therapeutic effects.
- highest mortalities seen immediately after handling and injection – consider diff. routes
- Viral loads measured from gill tissue (gills is a main target tissue for KHV, along w/ spleen and kidney)
Take-away:
- The 3-dose acyclovir protocol in this study was not effective in controlling KHVD long-term as similar viral loads and mortality were observed between treated and positive control groups at the end of the trial.
- There was a significant increase in survival in AT group after 2 doses of acyclovir and after fish had received 3 doses of acyclovir
A recent study investigated ntopical naltrexone as a treatment for lateral line depigmentation.
What is lateral line disease?
- What families are particularly susceptible?
- What are suspected etiologies?
- What treatments are traditionally used?
What are the effects of naltrexone on wound healing?
How did naltrexone treated fish heal compared to Ilex treated or control fish?
Journal of Zoo and Wildlife Medicine 54(1): 137–142, 2023
NALTREXONE AS A PROMISING TREATMENT FOR CLINICAL SIGNS OF LATERAL LINE DEPIGMENTATION IN PALETTE SURGEONFISH (PARACANTHURUS HEPATUS)
Megan M. Strobel, DVM, Kendra C. Baker, DVM, Aimee L. Berliner, DVM, Karisa N. Tang, DVM, MS, Dipl ACZM, Caitlin M. Hepps Keeney, DVM, and Gregory A. Lewbart, MS, VMD, Dipl ACZM, Dipl ECZM (ZHM) – rev by AJC
Abstract: Lateral line depigmentation (LLD) is a common condition in managed tropical saltwater fish, and treatment is somewhat elusive. Naltrexone, an opioid receptor antagonist, enhances epithelial cell replication, cytokine production, and angiogenesis to stimulate wound healing in mice. A treatment trial with 11 palette surgeonfish with LLD was performed. Seven fish underwent a single topical treatment of a mixture of 4 mg naltrexone and 10 g iLEX petroleum paste applied topically to LLD lesions. Four additional fish served as controls: two received only topical iLEX and two received no treatment. Severity of disease was scored on a 0–3 scale. Inflammatory response was gauged on a separate 0–3 scale for 5 d after treatment based on severity of erythema, as seen in a clinical case performed prior to this study. After 11 days, four affected animals that lacked an inflammatory response after naltrexone topical treatment were administered a single dose of intralesional 0.04% naltrexone (4 mg diluted into 10 ml saline). Lesions on all fish were photographed and measured at day 33. Clinical improvements in lesion size and pigmentation were apparent following topical naltrexone therapy in fish with severe lesions. Although these cases are promising, more data are needed to further evaluate the effectiveness of naltrexone 0.04% in treating LLD lesions in palette surgeonfish.
Key Points
* Lateral line depigmentation – focally depigmented to ulcerated skin along the lateral line of the head and flank, typically systemically unaffected though lesions can become secondarily infected
– SW surgeonfish and tangs (Acanthuridae) and anglefish (pomacanthidae) are particularly susceptible
– Postulated etiologies – environmental (activated carbon, ozone, high Cu, poor water quality, stray electricity, overcrowding), nutritional (inadeq Vit A or C in surgeonfish), and infectious (diplomonad flagellates or reoviruses)
– Treatment options include resolve inciting parameters & topical becaplermin
* Naltrexone – opioid receptor antagonist; topical low dose enhances wound healing via temporary intermittent blockade of the opioid growth factor to promote angiogenesis, and stimulate fibroblasts, epithelial cells, mast cells and collagen to create a granulation layer and have anti-inflamm effects on B and T immune cells
– Study investigated use of naltrexone for the treatment of clinical appearance of LLD
– Surgeonfish w/ LLD had greater improvement 33d after naltrexone tx compared to ilex only and control
– Fish w/ more severe initial LLD lesions had the greatest percentage of improvement
– Naltrexone treated fish had a greater reduction in wound size than illex or control fish
– Fish treated w/ naltrexone displayed normal blue pigmentation by day 33 vs one from the illex group had irreg black pigmentation in the treated region
- Differences in clinical response seen in animals w/ varying dz severities
* Inversely proportion relationship btwn inflammation score and percent change in LLD lesion
– Fish w/ higher inflammation scores had more notable clinical improvement, but were also more signif affected by LLD
* Red coloration of the skin seen w/ treatment 🡪 suspected to be due to inflammation
– Fish that did not have red coloration to the skin ( no signs of inflammation) were considered to have received an inadequate dose and were re-dosed with an injectable form of naltrexone
– Do NOT recommend injectable naltrexone application 🡪 carried addtl risk of iatrogenic complications and did not improve efficacy
Take Home
- Clinical improvements in lesion size and pigmentation was apparent following topical naltrexone therapy in fish with LLD, with the most with severe lesions showing the greatest improvement.
