Anseriformes

Question 1

Name the three famillies within Order Anseriformes

Answer 1

Anatidae – Ducks, geese, swans.

Anhimidae – Screamers.

Anseranatidae - Australian magpie goose Anseranas semipalmata.

Question 2

Unique anatomy of family Anhimidae (screamers)

Answer 2

o Screamers – Raucous territorial calls.
 Lack webbed feed and soft skin covered bill of other Anseriformes.
 Complex SC air sacs that can be contracted to make a crackling sound.
 Extensive pneumatization of bones including phalanges.
 No distinct ptrylae or feather tracts, even feather distribution.
 Strong flyers, form monogamous pairs.
 Entirely herbivorous, tongues keratinized and not fleshy like other Anseriformes.

Question 3

Complications of pinioning adult birds?

Answer 3

Repeated trauma to sx site

Large fibromatous nodules may form, prone to hemorrhage

Question 4

Waterfowl are primary reservoir for what viral disease in psittacines?

Answer 4

Avian Bornavirus

Neither cloacal nor fecal samples recommended for routine screening because of intermittent viral shedding. PCR can be performed on freshly plucked contour feathers or cropy biopsy.

Question 5

Which hemagglutinin subtypes are associated with increased pathogenicity in birds for AI?

Answer 5

H5, H7

Question 6

Clinical signs of HPAI in poultry?

Clinical signs of HPAI in anseriformes?

Answer 6

Range from decreased eggs to peracute death, diarrhea, neurologic signs, respiratory rales, sinusitis, edema of the head, cyanosis.

 Anseriformes – Inactivity, dullness, weakness, staggering, acute death, nasal discharge, lacrimation, mild diarrhea before death.
• Ddx – septicemic dz i.e. cholera, viral dz i.e. duck viral enteritis or exotic Newcastle dz, acute poisoninigs i.e. botulism.
• Gross path – Congestion, edema of organs, pericardial effusion, thickened air sacs, red-brown mottling of pancreas, hemorrhage in duodenum, firable liver with foci of necrosis.
• Histo – Congestion and necrosis, multiple organs, spleen, liver, GI, marked congestion and edema in lungs, cerebrum, nonsuppurative meningoencephalitis.
 Dx testing in US – USDA approved national animal health laboratory network (NAHLN) labs.
• USGS NWHC for wild bird samples.
• Current surveillance is passive and confined to mort events 500+ birds.
• Samples screened for influenza A by VI or RT-PCR on cloacal or pharyngeal swabs.
• Recommendation is to obtain both cloacal and pharyngeal swabs from wild birds.
• Any H5 or H7 avian influenza subtype immediately notifiable regardless of pathotype to USDA APHIS VS and OIE.

Question 7

What two NSAIDs have been associated with adverse side effects in waterfowl, and in which species?

Answer 7

Flunixin - Muscle necrosis at injection site in mallard ducks.

Ketoprofen - Mortality in eiders. Has been used in other waterfowl.

Question 8

Causative agent of duck plague?

Answer 8

Duck viral enteritis (herpesvirus)

Fecal-oral transmission, horizontal via contact with infected birds. Carrier state common.

Seasonal occurrence.
Peracute death, good BCS, depression, hemoatochezia, ulcer under tongue in carriers.

Annular bands of necrotic intestinal mucosa with hemorrhage in domestic ducks and mallards.

Myocardial petechiation.

Dx - VI from liver, spleen. Characteristic histologic appearance of lymphoid aggregates.

Management - Isolate carriers, depopulate, attenuated live-virus vaccine, carcasses should be collected and buried.

Question 9

Management of HPAI in waterfowl?

Answer 9

Cloacal or chonal swabs of living birds. If suspected, state and federal regulatory agencies should be contacted.

Question 10

Which bone is recommended as the best sample for bone marrow to make a diagnosis of starvation in waterfowl?

Answer 10

Ulna - Can be used on autolyzed and scavenged carccasses.

Question 11

What type of crystals in articular gout? What about pseudogout?

Recommended tissue fixation?

Answer 11

Monosodium urate crystals = gout.

Nonurate, calcium pyrophosphate crystals = pseudogout.

Tissues should be fixed in alcohol rather than formalin for dx of gout.

Question 12

Most mortalities from avian botulism due to which type of toxin (A-G)?

Mechanism of toxin?

Answer 12

Clostridium botulinum C

Toxin cleaves synaptic receptor proteins needed for acetylcholine release -> paresis, flaccid paralysis.

Classic “carcass-maggot” cycle = Ingestion of maggots from dead waterfowl infected with C. botulinum leads to concentration of botulinum toxin and death. Toxin accumulates in maggots.

Question 13

Avian Vacuolar Myelinopathy caused by a toxin produced by which organism?

Answer 13

Cyanobacterium - Aetokthonos hydrillicola.

Symmetrical vacuolation, demyelination, spheroid formation and gliosis of brain and spinal cord - white matter tracts of optic tectum consistent site.

Question 14

Which is the tissue of choice for diagnosis of lead intoxication in waterfowl?

Answer 14

Liver

• Lead intoxication (plumbism)
o Significant cause of mortality and morbidity in waterfowl
o Lead ammunition, ingestion of spent ammunition or tackle; in captivity – ingestion of lead-based pain
o CS: progressive weakness, green liquid feces (biliverdin), ataxia, weight loss
o Gross: green staining around vent, proventricular or exophageal impaction, lymphoid atrophy; SC edema, hydropericardium reported in geese & swans
o Histo: hepatocellular degeneration, hepatic cord atrophy, hemosiderosis, bile duct necrosis occasionally; renal tubular degeneration; myocardial fibrosis; lymphoid depletion
o Liver tissue of choice for diagnosis
o basophilic stippling of erythrocytes in mammals is not reported in birds

Question 15

Toxicity with which heavy metal has been associated with pancreatic lessions in waterfowl?

Answer 15

Zinc

Question 16

What is the toxic form of mercury?

Answer 16

Methylated mercury - lipid-soluble, can pass blood/brain barrier.

Question 17

What toxins are associated with the following algal blooms?

Blue-green algae
Paralytic shellfish poisoning
Neurotoxic shellfish poisoning
Amnesic shellfish poisoning
Nodularin poisoning

Answer 17

Blue-green algae - Microcystin, anatoxins. Massive hepatic necrosis.

Paralytic shellfish poisoning - Saxitoxin, blocks Na channels, enteritis.

Neurotoxic shellfish poisoning - Brevitoxin, blocks Na channels, Karenia brevis, meningeal infiltrates.

Amnesic shellfish poisoning - Domoic acid, Pseudonitzschia spp. Skeletal muscle necrosis and hemorrhage.

Nodularin poisoning - Nodularia spumigena, hepatic necrosis and hemorrhage.

Question 18

Mechanism of toxicity and clinical signs associated with organophosphates and carbamates in waterfowl.

Answer 18

• Organophosphates (OP) and Carbamates
o Inhibit acetylcholinesterase; sprayed on crops
o Acute, multi-species mortality event; death likely to respiratory paralysis
o Clinical Signs: muscle tremors, hyperexcitability, diarrhea, vomition, excessive salivation & lacrimation, piloerection, respiratory difficulty, miosis or mydriasis, paralysis, epistaxis, depression, opisthononus
o Exposure may predispose birds to predation or interfere with feeding
o No characteristic lesions on gross or histo – mild hemorrhage in the brain is sometimes seen

Question 19

What are the toxic components of oiling with petroleum products in waterfowl?

Answer 19

Polycyclic aromatic hydrocarbons

• Oiling with petroleum products
o Direct mortality – inhibition of thermoregulation, drowning from loss of buoyancy, direct intoxication, embryonic mortality in eggs
o Indirect mortality – anemia (Heinz bodies), reproductive effects, immunosuppresion
o Polycyclic aromatic hydrocarbons (PAHs) are the toxic components
o Gross lesions – oil covered plumage, emaciation, pulmonary congestion & hemorrhage, mucosal congestion & hemorrhage in GIT, involution of lymphoid tissues, pale enlarged liver
o Histo – hepatic lipidosis & hemosiderosis, adrenal necrosis, urate deposition, lipid droplets in lungs

Question 20

Perosis in ducklings and goslings associated with which vitamin and/or mineral deficiencies?

Answer 20

• Perosis- captive ducklings/goslings
o Hock dz, slipped tendons or bowed limbs; medial luxation of the Achilles tendon associated with vitamin (biotin, choline) and/or mineral (manganese) def.
o Bowed limbs- deformities of tibiotarsus poss assoc with niacin deficiency

Question 21

Chronic inflammation with pododermatitis has been linked to what renal/systemic issue?

Answer 21

Amyloidosis

• Amyloidosis
o Most common in birds is AA amyloid, which is a misfolding of SAA – the acute phase lipoprotein
o Secondary (reactive) amyloidosis with chronic inflammatory (typically pododermatitis or mycobacteriosis) or neoplastic disease or familial (abnormal SAA gene)
o Transmission of amyloidosis has been demonstrated which may explain outbreaks
o Gross lesions - Rounded, pale waxy liver- amyloid, sometimes splenomegaly or hepatic fracture
o Histo: pale hyaline eosinophilic deposits in liver and spleen that stain with Congo red (can be variable in nonmammalian species)

Swans appear especially sensitive (F8)

Question 22

What type of virus is duck plague/duck viral enteritis?

Which spp of duck is most susceptible?

Is this an OIE notifiable dz?

Answer 22

• Duck plague/ Duck Viral Enteritis (DVE)
o Alpha herpes virus- anatid herpesvirus-1; acute and highly contagious
o OIE notifiable dz; sudden death and high mortality
o Muscovy ducks are most susceptible - all members of Anatidae are the natural hosts
o Gross: petechial and ecchymotic hemorrhages in the heart & mesentery, multifocal necrosis in the GIT and lymphoid tissue, hepatomegaly with multifocal necrosis
 GI lesions start as hemorrhages but then progress to crusted plaques, and eventually coalesce into diphtheritic membranes
 Hemorrhage & necrosis of GALT is characteristic, forming button-like ulcers
o Histo: necrosis & hemorrhage in affected organs
 Eosinophilic intraocular (occasionally cytoplasmic) inclusion bodies are seen in the epithelial cells of the GIT.
o Pseudomembranous plaques at esophageal-proventricular junction and cloaca- almost pathognomonic

Question 23

What inclusions may be present in avian pox lesions?

Answer 23

Intracytoplasmic eosinophilic inclusions aka Bollinger bodies

Question 24

What virus is the etiologic agent for newcastle dz?

Answer 24

Newcastle disease (ND); avian paramyxovirus 1 (APMV-1)
o Genus Avulavirus, family paramyxoviridae
o CS: diarrhea, neuro signs, mortality
o Gross: hemorrhage and necrosis in GI mucosa, lymphoid organs, pancreas; degeneration of neurons in the brain
o Histo: nonsuppurative encephalitis with lymphocytes around vessels (in gulls)
o IHC for detecting virus

Question 25

What type of virus is wellfleet bay virus? What spp affected?

Answer 25

• Wellfleet Bayvirus (WFBV); Orthomyxoviridae
o Eiders in Massachusetts
o Route of transmission unknown – tick vector suspected
o Gross – foci of pallor in liver, pancreas; splenomegaly
o Histo – hepatic, splenic, pancreatic necrosis

Question 26

Clinical signs and lesions associated with aquatic bird bornavirus 1 (ABBV1)?

Answer 26

• Aquatic bird bornavirus 1 (ABBV1)
o Lymphoplasmacytic inflammation in the central, peripheral, and autonomic nervous system
o CS: lethargy, ataxia, lamaenss, hypermetria, torticollis, head tremors, stargazing, opisthotonos, suspected blindness
o Gross – upper GI impaction commonly observed
o Histo – gliosis & lymphoplasmacytic perivascular cuffs in brain, spinal cord, peripheral nerves and myenteric ganglia

Question 27

What are the two forms of fowl cholera and what is the etiologic agent?

Answer 27

• Fowl cholera; avian cholera; avian pasteurellosis
o Pasteurella multocida (gram negative coccobacillus)
o Common and important in both captive and free range
o CS: Two forms
 peracute septicemia (good condition, scattered petechial hemorrhage)
 chronic wasting (necrosis & petechiae in hepatic & splenic parenchyma, pulmonary consolidation
o Bacteria present in lesions – heart blood, liver, and bone marrow best for culture

Question 28

Lesions and diagnosis for mycobacterium avium in waterfowl?

Answer 28

• Mycobacterium avium
o Captive birds
o Gross – emaciation, caseous nodules in organs and tissues – liver is most commonly affected but spleen, lung, and intestine are also common; affected organs may be friable secondary to amyloidosis
o Histo – granulomatous inflammation or well defined granulomas with acid-fast bacilli within macrophages
o Diagnosis – bacterial isolation or PCR is gold standard – acid-fast staining is highly suggestive

Question 29

Salmonellosis in waterfowl associated most common with what salmonella spp?

Answer 29

Salmonella typhimurium

o Gross lesions – absent or hepatosplenomegaly with white foci, fibrinous exudate over serosal surfaces, hypopoyon, delayed yolk sac resorption, enteritis
o Histo: inflammation, gram-negative bacilli
o Diagnosis by isolation of bacteria

Question 30

Gram negative bacillus that causes septicemic disease with fibrinous polyserositis, tracheitis, bronchopneumonia, salpingitis in waterfowl?

Answer 30

Reimerella anatipestifer

o AKA New Duck Disease, Infectious Serositis, Pasteurella anatipestifer
o Gram negative pathogen that infects ducklings 1-7 weeks old (can also affect turkey poults 5-15 weeks)
o Clinical signs – oculonasal discharge, mild coughing and sneezing, tremors of head and neck that can progress to more severe neurologic signs
o Fibrinous exudate in the pericardium, over the liver, an in the air sacs and CNS can occur
o Diagnosis with PCR
o Treated with penicillin & streptomycin – limitations with food animal status
o Live bacterin vaccine is available

Question 31

Risk factors for aspergillosis in waterfowl?

Answer 31

• Aspergillosis- Aspergillus fumigatus
o Risk Factors – immunosuppression, malnutrition, concurrent disease, stressors like migration, oiling, captivity; host factors like age, nutritional condition, or species susceptibility
o Highly susceptible species – sea ducks, eiders, trumpeter swans
o Outbreaks are due to massive environmental exposure (moldy crops or feed) as the disease is not contagious
o CS – weakness, inability to fly, open mouth breathing, rales, tachypnea, cyanosis, dyspnea. Diarrhea, vomiting, and neurologic signs occur later in the disease; birds can asphyxiate from blockage of airways with fibrinonectrotic material
o Pathophysiology – spores inhaled, fungus grows within lungs and air sacs, hyphae invade vasculature and disseminate widely
o Gross – granulomas in subacute stage, thickening of the air sacs with raised, firm, flattened white-green caseous plaques that look like bread mold in later stages
o Histo - Mycete w/ parallel, spectate hyphae with dichotomous branching at 45-degree angles that stains with both Periodic acid-Schiff (PAS) and silver stains. Sometimes large conidiophores are seen; hyphae are associated with caseonectrotic, fiborous, and granulomatous lesions

Question 32

Ascarid nematode with a crustacean intermediat host and fish paretenic host, affects waterfowl.

Answer 32

Contracaecum

Question 33

Parasite found beneath the koilin layer in waterfowl.

Answer 33

• Amidostomum spp and Epomidiostomum spp.
o Found beneath the koilin later in waterfowl
o Intense infections cause mechanical damage to the koilin, alter GI motility, and result in emaciation
o Toxins produce dysphagia, dyspnea, and depression
o Impactions reported in tundra and trumpeter swams

Question 34

Trematodes within circulatory system or nasal sinuses of anseriformes, causes dermatitis in humans.

Answer 34

o Schistosome trematodes
 Live in circulatory system or nasal sinuses – lay eggs that disseminate via the blood stream
 Swimmers itch – dermatitis from embedded cercaria in people
 Anseriformes & chardriiformes parasites – different genera affect the different groups – bilharzia is found in most of the names
 Gross – emaciation, dehydration, pectoral atrophy; thrombosis of the caudal mesenteric vein, pulmonary congestion, gall bladder distension, empty GI tract
 Histo – lymphoplasmacytic to granulomatous inflammation; mineral associated with adults or eggs. Lamina propria edema, elongation of villi and distension of crypts

Question 35

Most pathogenic coccidia in ducks? Geese?

Answer 35

• Intestinal coccidiosis
o Eimeria, Isospora, Wenyonella or Tyzzeria spp.
o T. perniciosa is considered the most pathogenic coccidia in ducks; E. aythyae reported in outbreaks in lesser scaup
o E. Anseris is most important in geese
o CS – sudden death, depression, blood-stained vent, diarrhea, emaciation, pallor; distension of GI with necrohemorrhagic or caseous material
o Histo – multiple life stages of coccidia within mucosal epithelial cells

Question 36

Renal coccidiosis caused by what etiologic agent in geese?

Answer 36

• Renal coccidiosis
o E. truncata infections in geese
o Organisms mature in the kidney, occasionally in cloaca near ureter
o Asymptomatic in older birds, pathogenic in younger birds
o Gross – emaciated (young birds), enlarged, pale kidneys with multifocal to coalescing white foci
o Histo – destruction of tubular epithelium, tubules dilates with oocysts & inflammatory cells, interstitium infiltrated with lymphocytes, histiocytes, and lesser heterophils

Question 37

Parasitic dz in dabbling ducks, aka rice breast dz.

Answer 37

• Sarcocystis
o Most frequently seen in dabbing ducks
o Sarcosystis ryleyi is most common in NA waterfowl.
o Rice breast disease – sarcocysts grossly visible
o Histo – myocytes expanded by large protozoal cysts – not typically associated with inflammation or tissue necrosis

Question 38

What disease is characterized by chronically infected carriers with ulceration under the tongue?

Answer 38

Duck plague (Duck virus enteritis, DVE)
• Herpesvirus
• Outbreaks often assoc with stress
o 2 major outbreaks of duck plague in waterfowl in US
 1973 South Dakota ~40,000 ducks/geese died
 1994 New York ~1,400 ducks/geese
• Only waterfowl (ducks, geese, swans)
o Muscovies & blue-winged teal – highly susceptible
o Pintails – very resistant
o Has occurred repeatedly in tame/semitame waterfowl in many parts of US – in noted try to contain dz to prevent spread to wild.
• Reluctant to fly, blood stained vent & bloody fluid draining from mouth/nares, convulsions, death
• Hem on heart, hem/necrotic foci in liver, ulcerations with hem or raised yellow plaques in the esophagus or GIT
o Chronically infected carriers may have characteristic scabbed ulceration under their tongue (can shed periodically for the rest of their lives)
• Dx: presumptive with case hx & gross lesions, VI
• Trans: infected birds, contaminated environments (fairly stable in moist areas)

Question 39

Surf scoters implanted with intracoelomic transmitters had increased survival following premedication with what drug?

Answer 39

INTRANASAL ADMINISTRATION OF MIDAZOLAM HYDROCHLORIDE IMPROVES SURVIVAL IN FEMALE SURF SCOTERS (MELANITTA PERSPICILLATA) SURGICALLY IMPLANTED WITH INTRACOELOMIC TRANSMITTERS
Le Net R, Mulcahy DM, Santamaria-Bouvier A, Gilliland SG, Bowman TD, Lepage C, Lair S.
Journal of Zoo and Wildlife Medicine. 2019 Apr;50(1):167-75.

Midazolam intranasal after capture decreased 30-day mortality rate
Sedative effect for 17-82 min
No delay in anesthetic recovery

Conclusions: Intranasal administration of midazolam in surf scoters implanted with ICT was associated with increased survival.

Question 40

How does infection with HPAI originating from a shorebird host affect laughing gulls and mallard ducks in regards to infection and viral shedding?

Answer 40

SUSCEPTIBILITY OF LAUGHING GULLS (LEUCOPHAEUS ATRICILLA) AND MALLARDS (ANAS PLATYRHYNCHOS) TO RUDDY TURNSTONE (ARENARIA INTERPRES MORINELLA) ORIGIN TYPE A INFLUENZA VIRUSES
Charlie S. Bahnson, Rebecca L. Poulson, Laura P. Hollander, Jo A. Crum Bradley, and David E. Stallknecht. REVIEWED JKW.
Journal of Wildlife Diseases, 56(1), 2020, pp. 167–174

When inoculated with HPAIs from ruddy turnstones:

Laughing gulls did not develop infection

Mallards became infected and shed virus but no clinical signs

Conclusions: Laughing gulls are resistant to HPAIs from ruddy turnstones but mallards become infected and shed them. IAVs may be readily exchanged between RUTUs and ducks.

Question 41

Describe the pathogenesis of HPAI viruses in ruddy duck and lesser scaup?

How did infectious doses in ruddy ducks compare to mallards? What about shedding?

Answer 41

THE PATHOGENESIS OF CLADE 2.3.4.4 H5 HIGHLY PATHOGENIC AVIAN INFLUENZA VIRUSES IN RUDDY DUCK (OXYURA JAMAICENSIS) AND LESSER SCAUP (AYTHYA AFFINIS)
Spackman E, Prosser DJ, Pantin-Jackwood MJ, Berlin AM, Stephens CB.
Journal of wildlife diseases. 2017 Oct;53(4):832-42.

Wild waterfowl typically carry LPAIV rather than HPAIV
Designation of low-path vs. high-path is based on the virulence in gallinaceous birds
After inoculation with HPAI:
Most juvenile ruddy ducks died with no clinical signs
Inflammation of upper and lower respiratory tract, pneumonia
Focal necrosis of heart, brain, hepatocytes
Mild lymphoid depletion in spleen and cursa
Adult ruddy ducks had no clinical signs nor mortality and brief viral shedding
One adult ruddy duck died with hemorrhagic enteritis from a different disease
Juvenile lesser scaups had no signs nor death but shed virus
Similar to common eiders
Infectious doses in ruddy ducks were similar to mallards
Mallards are much more likely shed HPAI than ruddy ducks or lesser scaups.

Conclusions: HPAI causes mortality in juvenile ruddy ducks but not in adults, lesser scaups, common eiders, or mallards. Mallards are better at shedding virus than ruddy ducks or lesser scaups.

Question 42

What is the etiologic agent of wellfleet bay virus?

What is the seroprevlence of wellfleet bay virus in regards to location (Massachusetts, Maine, Nova Scotia, Quebec)?

Answer 42

PREVALENCE AND DISTRIBUTION OF WELLFLEET BAY VIRUS EXPOSURE IN THE COMMON EIDER (SOMATERIA MOLLISSIMA).
Ballard JR, Mickley R, Gibbs SE, Dwyer C, Soos C, Harms NJ, Gilchrist HG, Hall JS, Franson JC, Milton GR, Parsons G, Allen B, Giroux JF, Lair S, Mead DG, Fischer JR.
J Wildl Dis. 2017 Jan;53(1):81-90.

Background:
Wellfleet Bay virus (WBV) is a vector-borne, novel RNA orthomyxovirus
Caused recurrent morality events in the Dresser’s subspecies of common eider in spring and autumn
WBV lesions = hepatocellular, pancreatic, and splenic necrosis
This study assessed Dresser’s common eider for WBV seroprevalence in from 2006-2014

Key Points:
Seroprevalence was highest in birds sampled in Massachusetts compared to Maine, Nova Scotia, and Quebec

In MA, females had higher prevalence in breeding season, males had higher in non-breeding season

Overall, prevalence was independent of sex, age, or season

No positive northern subspecies of common eider

A few birds were caught repeatedly and were showed revert to antibody-negative status

Conclusions: Wellfleet Bay virus exposure was detected in Dresser’s subsp. of common eider with the highest prevalence in Massachusetts.

Question 43

Clinical signs of zinc toxicity in waterfowl?

Answer 43

Diabetes Mellitus With Concurrent Cerebellar Degeneration and Necrosis in a Domestic Goose (Anser anser domesticus).
DiGeronimo PM, Crossland NA, Jugan A, Nevarez JG, Tully TN Jr, Evans DE.
J Avian Med Surg. 2018 Jun;32(2):122-127.

Key Points:
The function of avian pancreas and efficacy of exogenous insulin is still unknown

Birds typically have higher glucagon and lower insulin levels than mammals

Zinc interferes with exocrine pancreatic functions

Typical signs of zinc toxicity in ducks include weakness and inappropriate mentation

Resolve with removal of zinc-laden ingesta

Signs of diabetes mellitus in birds include polyphagia, emaciation, PU/PD

The pathophysiology of diabetic neuropathy is still unknown, but may cause glycation of lipids and proteins

Birds seem to be more resistant to producing these activated glycation end-products

This is the first report of a central neuropathy secondary to diabetes mellitus in a bird

Conclusions: Zinc toxicosis in a Toulouse duck cause pancreatic insufficiency and secondary diabetes mellitus, leading to cerebellar degeneration.

Question 44

What is the difference between enucleation and evisceration for ocular surgery in birds? Why might you choose evisceration over enucleation?

Answer 44

Successful chemical ablation of an intraorbital cyst caused by an eyelid injury and iatrogenic ankyloblepharon formation in a duck.
Park SA, Davidson H, Thompson KA, Smith RP, Noland E, Sledge D, Thomas JS, Komáromy AM.
J Am Vet Med Assoc. 2018 Nov 1;253(9):1164-1168.

Key Points:
Intraorbital cysts typically develop when residual adnexal structures remain after enucleation

Cyst was likely caused by tear production from residual adnexal tissue

Enucleation was not performed in this case because of the risks of enucleation in birds (Murray 2013):

Tight encasement of the globe in the orbit

Presence of scleral ossicles

Fragile, thin orbit

Short optic nerve

In enucleation, the globe, third eyelid, and conjunctiva are removed

In evisceration, only cornea and inner contents of the globe are removed

In birds, most tears are secreted by the Harderian gland, which is located near the third eyelid

Birds have superior and inferior lacrimal puncta at the medial canthus

Important to keep intact when performing surgery

Conclusions: Disruption of the lacrimal puncta during ocular surgery in birds may predispose to intraorbital cyst, which can be treated with intraorbital gentamicin.

Question 45

What is the main blood supply for the distal avian limb?

Answer 45

A Novel Technique for Extracapsular Repair of the Intertarsal Joint in a Duck.
Baron HR, Phalen DN, Gonzalez MS.
J Avian Med Surg. 2018 Mar;32(1):57-64

Background:
Intertarsal joint consists of tibiotarsus (fused tibia and proximal row of tarsal bones) and tarsometatarsus (fused distal row of tarsal bones and metatarsal bones II, III, IV) in a synovial roll-and-glide joint

Ligaments of the intertarsal joint:

Medio-lateral stability provided by medial and lateral collateral ligaments

Craniocaudal (and some mediolateral) stability provided by lateral tibial meniscal, lateral metatarsal meniscal, and medial tibio-metatarsal ligaments

Muscles and movement of the intertarsal joint:

Flexion achieved by cranial tibial m.

Extension achieved by gastrocnemius m. (3 bellies that inserts as a single tendon onto the hypotarsus)

Medial rotation achieved by fibularis brevis m.

Vessels and nerves in the intertarsal joint:

Deep fibular n. and cranial tibial artery and vein lie ventral to tendon of the cranial tibialis muscle

Cranial tibial artery = main blood supply for distal limb

Cranial tibial vein and medial metatarsal vein = main venous drainage

There are a few reports of stifle extracapsular repair in birds

Conclusions: Extracapsular repair of a medial collateral ligament of the intertarsal joint provided a good clinical outcome in a Pekin duck.

Question 46

In what avian species were sensitivity and specificity of ELISA for detection of AIV subtype H5 antibodies in zoo birds highest?

For which spp were sensitivity and specificity lowest?

Describe overall sensitivity and specificity for AIV ELISA vs hemmaglutination inhibition (gold standard).

Answer 46

Evaluation of a commercial competitive enzyme-linked immunosorbent assay for detection of avian influenza virus subtype H5 antibodies in zoo birds.
Jensen TH, Andersen JH, Hjulsager CK, Chriél M, Bertelsen MF.
Journal of Zoo and Wildlife Medicine. 2017 Sep;48(3):882-5.

The hemagglutination inhibition (HI) test is the current gold standard for detecting antibodies to avian influenza virus (AIV). Enzyme-linked immunosorbent assays (ELISAs) have been explored for use in poultry and certain wild bird species because of high efficiency and lower cost. This study compared a commercial ELISA for detection of AIV subtype H5 antibodies with HI test of 572 serum samples from zoo birds. There was no significant difference between the results of the two tests when statistically compared by a McNemar χ2 test (P = 0.86) and assessment of κ (κ = 0.87). With a specificity of 94.2% (95% confidence interval [CI], 0.92-0.97), a sensitivity of 93.9% (95% CI, 0.91-0.97), and an excellent correlation between the two tests, this ELISA can be recommended as an alternative to the HI test for preliminary screening of zoo bird sera for antibodies to AIV subtype H5.

Background:

Highly pathogenic avian influenza (AI) = H5 and H7 subgroups

ELISAs are better than hemagglutination inhibition (HI) because they are faster, more throughput, and don’t require virus isolation

Penguins, pelicans, guinea fowl, and Inca terns have shown a low response to AI vaccination historically

This study collected birds before and after vaccination with an H5N9 inactivated AI vaccine

Key Points:
ELISA had a high sensitivity and specificity that had very good agreement with HI

Could use ELISA as screening and HI as second test in a zero-tolerance scenario

Sensitivity and specificity was:
Highest for Galliformes (the test is designed for chickens)

Lowest for Sphenisciformes, then Phoenicopteriformes

Conclusions: IDvet ELISA for H5 avian influenza is a good screening test for zoo birds, but is least accurate in penguins and flamingos.

Question 47

What were the effects of meloxicam or tramadol vs control for weight bearing in ducks following induced arthritis?

Answer 47

Analgesic Efficacy of Tramadol Compared With Meloxicam in Ducks (Cairina moschata domestica) Evaluated by Ground-Reactive Forces
Ryan S. Bailey, Julie D. Sheldon, Matthew C. Allender, Michael J. Adkesson, Sathya K. Chinnadurai
J. of Avian Medicine and Surgery, 33(2):133-140 (2019).

Background:
Hispaniolan Amazon - meloxicam 1mg/kg dose needed to change weight bearing

Tramadol - active ingredient is O-desmethyltramadol metabolite (mu opioid agonist)

Also activity at kappa + delta receptors + inhibits reuptake of norepi and serotonin

Analgesia in kestrels and Amazons

Key Points:
Improved weight bearing with meloxicam or tramadol compared to control at 3 and 4 h

No difference in between tramadol and meloxicam groups

Monosodium urate-induced arthritis only lasted for 8 hours

Conclusions: Tramadol 30 mg/kg and meloxicam 1 mg/kg PO to muscovy ducks is antinociceptive at hours 3 and 4 post- 3% monosodium urate injection into the intertarsal joint.

Question 48

Unique cardiac conduction system in birds?

Direction of mean electrical axis in birds vs mammals? Why?

Answer 48

Pugliese, M., La Maestra, R., Morici, M., De Majo, M., & Spadola, F. (2020). Normal Electrocardiographic Pattern in Conscious Healthy Domestic Geese (Anser anser). Journal of Avian Medicine and Surgery, 34(4), 358-363.

• Key Points:
  o Unique cardiac conduction system in birds (general, varies in some spp):
   Middle branch of the bundle of His.
   Subepicardial Purkinje network.
   Truncobulbar node.
   Ring of Purkinje.
  o Anatid birds:
   Electrical impulse generated by SA node -> AV node along specialized conduction fibers in the interatrial septum, which originate in the RA between the entrance of the right cranial vena cava and caudal vena cava.
  • Atrial depolarization = P wave.
   AV node between interatrial and IV septum conducts the impulse to the atrioventricular bundle (Purkinje fibers).
  • QRS – Ventricular depolarization.
   Time between P and QRS
  o Birds manually restrained in ventral recumbency until HR and body temp were WNL and considered to be minimally stressed.
   Lead placement – Propatagium L and R wing, inguinal skin L and R legs.
  o Sinus rhythm detected in all animals.
  o All geese – Mean electrical axis on frontal plane negative, range -140 to -30 deg.
   Same as other avian species.
   Depolarization of the ventricles originates from the subepicardial layer and advances to the myocardium and endocardium.
  • Unlike mammals, where it begins in the subendocardium.
  • This anatomy specifically results in a negative polarity for the QRS complex in leads II, III, and aVF, and thus a negative MEA.
  o Amplitude of deflections in lead 1 consired too small to evaluate the morphology of the waves.
   Bipolar leads II, III, and unipolar leads aVR, aVf, and aVL were useful and analyzed.
  o PR interval shorter than dogs and cats, similar to other bird spp.
  o ARS negative prevailing wave in leads II and III and positive prevailing wave in aVL, aVF, aVR.
• Takeaway: Similar to other avian species. Unlike mammals, MEA is negative due to depolarization of the ventricles originating from the subepicardial layer in birds.

Question 49

A recent paper described the use of antibiotic impregnated calcium beads after IVLP was insufficient to clear septic tenosynovitis and osteoarthritis in a pekin duck.

What are some of the advantages and disadvantages of antibiotic impregnated calcium sulfate beads?

Answer 49

Treatment of Septic Tenosynovitis and Osteoarthritis in an American White Pekin (Anas platyrhynchos domesticus) with Repeated Intravenous Regional Limb Perfusion and Antibiotic-Impregnated Calcium Sulfate Beads.
Lacqua A, Helmer P.
Journal of Avian Medicine and Surgery. 2023;36(4):414-20.

Key Points:
- Calcium sulfate beads have several advantages over polymethylmethacrylate beads
– Osteoconductive
– Resorbable, don’t require second procedure for removal
– Predictable antibiotic eluting properties
– Less thermogenic
- Complications of calcium sulfate beads can include
– Extruding throughout the surgical site
– Wound drainage
– Hypercalcemia - signs not reported with their use

Question 50

A recent study evaluated the pharmacokinetics of acetaminophen in geese.

What were the two treatment groups?
- What was oral bioavailability like?

What histopathology was noted following treatment?
- What has been seen in other species?

Answer 50

JAVMA 2022 260(12)
Acetaminophen pharmacokinetics in geese

Key Points:
- APAP plasma concentrations were lower compared to those of the metabolites at almost all of the selected time points after both treatments
- A secondary-peak was observed in plasma APAP concentration 4 hours after IV administration in all the animals.
– Surprisingly, this peak did not occur after PO treatment nor in metabolite concentration profiles–possibly due to enterohepatic recycling
- After IV treatment, the APAP area under the curve was significantly higher than that found after PO administration, resulting in an oral bioavailability of 46%.
– Moderate bioavailability and in line with those from other avian species
- The area under the curve for metabolites was higher than for IV administration
– May be due to different intestinal enzymes
- after 1 PO dose, APAP residues were higher in the liver and lung compared to the other tissues, and highest in the liver
- No histological alterations in the morphology of stomachs, duodenal wall, and kidneys were observed in any of the examined birds
- A normal and typical structure of the liver was found in all the geese at 1, 4, and 10 hours after drug administration.
– However, the goose liver samples collected at 24 hours after drug administration showed dilated capillaries and lipid accumulation in hepatocytes
– liver necrosis and tubular nephrotic changes were previously observed in chickens after a single PO dose of 20 or 40 mg/kg
- No adverse effects were observed during or after the experimental trial in any of the animals.
- No signs of toxicity were found in the kidney which is the main site of toxicity for NSAIDs
- The toxicity evaluations performed in the present research cannot lead to a rigorous conclusion since multiple dose and efficacy studies are required to better assess the severity of hepatotoxicity at the therapeutic dose (unknown yet) in geese
- Doses higher than 10 mg/kg should be avoided since mild or severe hepatotoxic effects may occur.

Question 51

A recent study described the morbidity and mortality of reticuloendotheliosis virus in hawaiian geese and laysan albatross.

What type of virus is reticuloendotheliosis virus?
- What pathology does it typically cause?
- What order does it typically affect?

What coinfections were present in these birds?

Answer 51

JWD 58.4 (2022).
MORBIDITY AND MORTALITY OF HAWAIIAN GEESE (BRANTA SANDVICENSIS) AND LAYSAN ALBATROSS (PHOEBASTRIA IMMUTABILIS) ASSOCIATED WITH RETICULOENDOTHELIOSIS VIRUS
Thierry M. Work; Renee Breeden; Julie Dagenais; … James W. Casey

Key Points:
- Reticuloendotheliosis Virus (REV):
– Retrovirus in Avian Leukosis Group
– Causes lymphoid and reticulum cell neoplasia in chickens
– Seen in Galliformes, but not commonly in the other 10 orders it is known to infect
– Uniquely originated from mammalian virus that infected Plasmodium and jumped to birds
– REV genome can integrate into Gallid Herpesvirus 2 and Avipox viruses – previously contaminated vaccines which led to outbreaks in poultry flocks
- In this case series, two Nenes and one albatross had REV identified on IHC and PCR
– Second virus ever identified in Hawaiian wild birds
– In Hawaii, only virus known to affect wild birds was Avipox
– One of the Nene’s had disseminated histiocytoma, one of the Nene’s had toxoplasmosis, and the albatross had avipoxvirus.
- Enemy Release Hypothesis: parasites are usually absent in remote island populations - only the fittest individuals survive the transport, intermediates and vectors likely absent
- This study may be the first to find REV in a pelagic seabird

Question 52

A recent study established reference intervals and compared four point-of-care devices for biochemistry evaluation of canvasbacks.

What is the scientific name of the canvasback?

What values were comparable on all analyzers?

What values were useful for the VetScan v the i-STAT?

Answer 52

Reference values and comparison of blood chemistry and plasma protein values between gold standard analyzers and four point-of-care devices in free-ranging canvasbacks (aythya valisineria).
Anderson NL, De La Cruz SE, Brenn-White M, Frankfurter G, Ziccardi MH, Martínez-López B.
Journal of Zoo and Wildlife Medicine. 2022;53(2):302-318.

Conclusions
- VetScan: AST, CA, Gluc, UA and corrected Alb, K, Na, TP were interchangeable with benchtop chemistry analyzer (COBAS)
- i-STAT: glucose, K, corrected Na, Cl were interchangeable with gold-standard
- Glucose on all tested analyzers were interchangeable
- Use of i-STAT CHEM8+ is not recommended for measuring TCO2 in canvasbacks or other Anatidae species without validation
- Canvasbacks in this population had higher Na, Cl, CK, AST and hatch year had higher ALP
– No other age or sex differences during this nonbreeding period study
- Corrections can be achieved using the table of coefficients and the equation: Corrected value = intercept + slope x raw value