49(4), (1 December 2018) https://doi.org/10.1638/2018-0022.1
ANALYSIS OF HISTORICAL MEDICAL RECORDS OF CALIFORNIA CONDORS
(GYMNOGYPS CALIFORNIANUS) ADMITTED FOR LEAD EXPOSURE TO THE LOS
ANGELES ZOO AND BOTANICAL GARDENS BETWEEN 1997 AND 2012: A CASE
SERIES STUDY
Natalie Nguyen, Miguel D. Saggese, and Curtis Eng
Lead toxicosis remains the primary cause of death in wild
populations of California condors (Gymnogyps californianus). Many
condors require medical intervention with lead chelation therapy,
among other conservation measures, to survive in the wild. An
analysis of historical medical records of California condors
admitted for lead exposure to the Los Angeles Zoo and Botanical
Gardens (LA Zoo) between 1997 and 2012 was performed to investigate
clinical presentation, radiographic findings, and treatment along
with the potential impact of these factors on recovery and
successful release back into the wild. Of 100 individual condors
presented to the LA Zoo for suspected lead toxicosis during this
period, 84 condors had records for initial laboratory blood lead
levels. For these 84 condors (40 [47.6%] females and 44 [52.4%]
males), 277 initial laboratory blood lead levels in total were
recorded because of repeated admissions. Thirty-two (38%) condors
were admitted once to the zoo and 62% were admitted two or more
times. Clinical signs were not observed in 87.5% of the condors
admitted with median blood lead concentrations of 26 μg/dl. Of the
radiographs taken on initial presentation, 65% did not show
evidence of gastrointestinal metallic foreign bodies. Various
treatments protocols with edetatum calcium disodium,
dimercaptosuccinic acid, and lactated Ringer's solution were
documented in the medical records. Of the 277 admissions, 154
admissions had a recorded outcome posttreatment of which 140 (91%)
admissions were released back to the wild. This study contributes
to a better understanding of how intervention and therapeutic
approaches have been essential for the recovery, release, and
sustainability of these birds as a wild population. Consistency in
data collection of California condors admitted for diagnosis and
treatment of lead toxicosis is needed to better assess the impacts
of medical interventions.
Introduction:
· California condor – opportunistic scavenger, largest soaring
bird in N. America, critically endangered
· In 1985, all remaining (n=23) wild condors brought into
captivity to recover species and release
· Now there are >400 condors
· Primary cause of death: lead toxicity
· Other causes: microtrash ingestion, power line collision,
gunshot, strychnine, wildlife predation
· Lead toxicity is chronic – ammunition shatters the condors
ingest small amounts with feeding
· *During fall hunting season worse
· Clinical signs only develop when levels are
significant
· Bone accumulates lead over time. Some lead in bone is
available to chelation but most is not. Therefore, as bone is
slowly remodeled and under times of stress, lead is released back
into blood - this can result in repeated toxicity events
· to mitigate: feeding stations deployed & condors are
checked for lead levels and chelated when necessary
Diagnosis:
· Blood lead and radiographs
· unexposed (<20 ug/dl); exposed or subclinical (20–59
lg/dl); clinically exposed (60–99 lg/dl); exhibiting acute toxicity
(>100 lg/dl)
· Blood lead half life is 13 days, so reflects only ACUTE
exposure (can use feather vane lead concentrations or lead isotope
ratios to diagnose chronic but this is not commercially
available)
· Note: blood lead absorption in GIT is inversely proportional
to metal particle size
Clinical Signs: crop stasis, neurologic signs, behavioral
changes, weakness, weight loss, traumatic lesions (more likely with
chronic exposure)
Treatment: chelation with CaEDTA and/or DMSA, subcutaneous
fluids, supportive care
· If rads indicate metal FB: they also feed increased fur
or skin to encourage casting or passing of material or add psyllium
to encourage passing. They then screen feces radiographically to
ensure metal has been passed. If not, will do surgery as mandatory
to have no metal FB on rads in order to release
M&M
· Retrospective; Medical records reviewed of 84 California
condors with 277 total admissions to LA Zoo for suspected lead
toxicity
Results/discussion:
· No difference in sex (similar percentage)
· Age was NOT associated with initial lead level or outcome but
majority of those affected were bw 2-6 yrs
· < 2 yrs old may be at lower risk bc not exploring as
far
· Subadults are mobile and exploring range, are higher ranking
socially than younger birds thus consuming carrion first, and may
be over-represented in pop’n (thus bias)
· > 6 yrs tend to stay closer to breeding territories
· Authors felt that the LeadCare analyzer overestimated levels
in field when compared to lab values
· Must take into account CS and other risk factors when deciding
whether to admit to rehab
· Only n=18 birds had CS: crop stasis, neuro signs, behavior
changes, weakness, weight loss, trauma
· Considered for release once blood lead < 35 ug/dl
Take-home points:
· Lead toxicosis is leading cause of death of California
condors
· Many (62%) are admitted for treatment at rehab center more
than once
· Clinical signs not seen in the majority (87%)
· More than half (65%) do not have GI metallic foreign body on
radiograph
· Most (91%) are released after treatment and blood lead levels
were not correlated with outcome
· Intervention and treatment has been essential to recovery of
this species population
· Important to understand acute v. chronic and the implications
for bone and soft tissue to be a source of chronic lead release
into blood, even when blood lead levels have decreased and no metal
FB present.
Journal of Avian Medicine and Surgery. 2018 Mar;32(1):34-40.
The Use of Lead Isotope Analysis to Identify Potential Sources
of Lead Toxicosis in a Juvenile Bald Eagle (Haliaeetus
leucocephalus) With Ventricular Foreign Bodies
Dana Franzen-Klein, David McRuer, Vincent A. Slabe, Todd
Katzner
Abstract: A male juvenile bald eagle (Haliaeetus leucocephalus)
was admitted to the Wildlife Center of Virginia with a left humeral
fracture a large quantity of anthropogenic debris in the
ventriculus, a blood lead level of 0.616 ppm, and clinical signs
consistent with chronic lead toxicosis. Because of the poor
prognosis for recovery and release, the eagle was euthanatized.
Lead isotope analysis was performed to identify potential
anthropogenic sources of lead in this bird. The lead isotope ratios
in the eagle’s femur (0.8773), liver (0.8761), and kidneys (0.8686)
were most closely related to lead paint (0.8925), leaded gasoline
(0.8450), and zinc smelting (0.8240). The lead isotope ratios were
dissimilar to lead ammunition (0.8179) and the anthropogenic debris
in the ventriculus. This case report documents foreign body
ingestion in a free-ranging bald eagle and demonstrates the
clinical utility of lead isotope analysis to potentially identify
or exclude anthropogenic sources of lead poisoning in wildlife
patients.
Case Report
· Bald eagle presented to wildlife clinic. Euthanized.
· Clinical signs of chronic lead toxicity
· To determine the lead source, ventricular contents and samples
of kidney, liver, femur were sent to the MSU for lead concentration
and isotope analysis
· Elevated lead in the femur, liver, and kidney
· Isotope ratios were most closely related to lead paint, leaded
gasoline, and zinc smelting
· Isotopes did not appear closely related to ammunition.
Discussion
· Poisoning most common cause of death of carcasses submitted to
the National Wildlife Health Center from 1982 to 2013
· Lead poisoning in > 60% of poisoned birds
· The 3 main sources of environmental lead:
· 1) ammunition
· 2) fishing sinkers and jigs – both via direct ingestion.
· 3) mining and smelting industry
· Indirect: contaminated water, prey, or direct ingestion of
man-made objects
· Lead has 4 main isotopes. Different sources have unique
isotope ratios.
· Bone, liver, and kidney levels were several orders of
magnitude higher than the blood lead level.
· Blood and soft tissue lead levels reflect recent lead exposure
or leaching from bone
· Bone lead levels reflect chronic lead exposure
Take Home: Lead isotope ratios in this bird were dissimilar to
lead ammunition, suggesting environmental sources other than
ammunition may be contributing to lead poisoning in this
species. Lead has multiple isotopes and test can help reveal
to source because different sources have unique isotope ratios.
Journal of Wildlife Diseases, 53(4), 2017, pp. 816–823
INFLUENCE OF SNOWFALL ON BLOOD LEAD LEVELS OF FREE- FLYING BALD
EAGLES (HALIAEETUS LEUCOCEPHALUS) IN THE UPPER MISSISSIPPI RIVER
VALLEY
Lindblom, Reichart LM, Mandernack BA, Solensky M, Schoenebeck
CW, Redig PT
ABSTRACT: Lead poisoning of scavenging raptors occurs primarily
via consumption of game animal carcasses containing lead, which
peaks during fall firearm hunting seasons. We hypothesized that
snowfall would mitigate exposure by concealing carcasses. We
categorized blood lead level (BLL) for a subsample of Bald Eagles
(Haliaeetus leucocephalus) from the Upper Mississippi River Valley
and described BLL with respect to age, sex, and snowfall. We
captured Bald Eagles overwintering in the Upper Mississippi River
Valley (n=455) between December 1999 and January 2002. Individual
BLL ranged from nondetectable to 335 lg/dL, with 73% of the samples
testing positive for acute exposure to lead. Eagle BLL did not
significantly differ between age or sex, but levels were higher
immediately following the hunting season, and they were lower when
the previous month’s snowfall was greater than 11 cm. This study
suggests a window of time between the white-tailed deer (Odocoileus
virginianus) hunting season and the onset of snow when the
population experienced peak exposure to lead. Combining these
findings with existing research, we offer a narrative of the annual
lead exposure cycle of Upper Mississippi River Valley Bald Eagles.
These temporal associations are necessary considerations for
accurate collection and interpretation of BLL.
Introduction
· Elevated lead in the winter or around hunting season
· Snowfall may cover lead-tainted carcasses and decrease lead
exposure
· Bald Eagles locate prey by sight
· Half life of blood led level (BLL) is about 2 weeks
M&M:
· 55 BAEA over 3 winter periods from early December to March
1999-2002
· Lead tested by graphite furnace atomic absorption
spectrophotometry
· Separated lead into exposure level (<10 ug/dL =
absent/background, 10-19 = elevated exposure, 20-59 = subclinical,
60-99= clinical, >100 = acute toxicity)
Results
· 73% of sampled had positive lead exposure
· Most had elevated exposure > background > subclinical
> clinical > acute tox
· Highest average lead levels were January > December >
March > February
· Higher in early winter during and following the deer hunting
season
· No significant difference between sex or age group
· Significantly higher BLL values were associated with little to
no snow (<3cm).
· Lower BLL in months with high snow (>11 cm)
Discussion
· Supports hypothesis that snowfall may cover lead carcasses and
decrease consumption
· This study had light snow in early winter and heavy snow in
the late winter
· Combining with other data, lead-tainted deer are highest in
early winter
· Other clinical data showed a rise in BLL in march coinciding
with melting snow
· In March, BAEA tend to migrate and consume fish leading to
decreased BLL
· Underestimates lead toxicity as only live birds were
sampled
Inclusion Body Herpesvirus Hepatitis in Captive Falcons in the
Middle East: A Review of Clinical and Pathologic Findings
Raj Raghav, and Jaime Samour
Journal of Avian Medicine and Surgery 33(1):1–6, 2019
Taxonomy: Falconiformes (order) → Falconidae (family) → Falco
(genus)
Abstract: Inclusion body hepatitis in falcons is caused by a
herpesvirus designated Falconid HV-1. This herpesvirus and other
herpesviruses affecting birds of prey have not been assigned to a
genus and include inclusion body herpesvirus hepatitis in eagles
(Accipitrid HV-1) and inclusion body herpesvirus hepatitis in owls
(Strigid HV-1). Herpesvirus infections have been diagnosed in both
captive and free-living raptors across Europe, North America, and
Asia in different species of the family Falconidae. Herpesviruses
affecting owls and falcons have been found to be antigenically
similar to pigeon herpesvirus (Columbid HV-1) and distinct from
other avian herpesviruses. When the herpesvirus isolates from owls,
falcons, and pigeons were compared by sequencing a fragment of the
herpes viral DNA polymerase gene from those birds naturally
infected with the virus, the sequences from these 3 sources were
found to be nearly identical. The authors of this study concluded
that the Falconid HV-1, Strigid HV-1, and Columbid HV-1 were the
same virus. Furthermore, the authors also proposed that the virus
therefore be referred to as Columbid HV-1 (CoHV-1), because pigeons
may be responsible for the transmission of the virus to birds of
prey. Pigeons are often carriers of the virus without showing any
clinical signs. It has long been suspected that raptors may
contract the infection by the ingestion of infected pigeons. Some
studies have suggested that falcons may not contract the infection
through the oral route by ingesting carrier pigeons, but through
the ocular or nasal route. Inclusion body herpesvirus hepatitis is
a frequently diagnosed disease in the captive falcon population
used for falconry, racing, and breeding in the Middle East, and it
seems to be associated with the extensive use of pigeons for
training and as a food item. This paper reviews the clinical and
pathological findings in falcons affected by inclusion body
herpesvirus hepatitis in the Middle East.
Introduction:
· Herpesvirus have double-stranded DNA, a linear genome, a
protein capsid, and an envelope
· All bird herpesviruses are within subfamily alphaherpesvirinae
so far
· CoHV-1 (columbid herpesvirus), Strigid HV-1, and FaHV-1 are
closely-related, if not identical viruses
· FaHV-1 (falconid herpesvirus) differs by one gene from
CoHV-1
· Clinical signs of these viruses are very similar and 100%
fatal to falcons
· Viral replication in the liver (causing hepatitis) and
epithelial cells of the intestines and renal tubules
· Destroyed bone marrow preventing an inflammatory response
· Because pigeons are asymptomatic carriers of CoHV-1, contact
with pigeons puts raptors at risk for infection
· Route of transmission is possibly ingestion or direct
contact
· Do not feed pigeons of unknown herpesvirus status to birds of
prey
· Virus has low survivability in the environment
Clinical Diagnosis of Falcons with Inclusion Body Herpes Virus
Hepatitis
· Clinical signs: Nonspecific (reduced preening activities,
severe depression, anorexia, regurgitation, vomiting,
biliverdinuria, sudden death), very rarely CNS → death within 24-72
hours
· Clinical pathology: Anemia, leukopenia, heteropenia, toxic
changes, elevated CK, AST and bile acids
· Necropsy findings: Hepatosplenomegaly with small yellow
necrotic foci on liver, spleen, intestines, bursa, kidneys,
pancreas, and gonads
· Histology: Intranuclear eosinophilic inclusion bodies in cells
on the periphery of lesions
· Adenovirus also has large intranuclear inclusions in
hepatocytes, but usually adenovirus is basophilic
· Diagnosis: hepatic biopsy with intranuclear eosinophilic
inclusion bodies
· Treatment: Supportive care + acyclovir 80 mg/kg PO q8h +
quarantine
· Mortality in falcons = 100% despite treatment
· Vaccination: No vaccine for falcons, though viruses are in
development can reduce viral excretion of pigeons
Conclusions: FaHV-1 and CoHV-1 are closely related. CoHV-1 is
likely infecting raptors when they come in contact with pigeons as
a food source, causing causes acute clinical signs and death. No
treatment. No vaccine.
Evaluation of Goniometry and Electrogoniometry of Carpus and
Elbow Joints in the Barred Owl (Strix varia)
Jenessa L. Gjeltema, Laurel A. Degernes, Halley D. Buckanoff,
Denis J. Marcellin-Little
Journal of Avian Medicine and Surgery 32(4):267–278, 2018
Taxonomy: Strigiformes (Order) → Strigidae (family) → Strix
(genus)
Abstract: The motion of wing joints is a critical factor for
successful flight in avian patients, but little information is
available about goniometry in birds. Elbow and carpus joints in
flexed and extended positions from 10 orthopedically normal wings
of 6 adult wild barred owls (Strix varia) were evaluated with the
animals under general anesthesia using a modified universal plastic
goniometer and an electrogoniometer. These measurements were
compared to those obtained using radiographic assessment. Intra-
and interobserver reliability was calculated. Measurements in live
animals were compared to those obtained from frozen-thawed
carcasses. Results showed that the modified universal plastic
goniometer can be used to obtain accurate results for elbow flexion
and extension and for carpal flexion with good to excellent
reliability compared to measurements collected from radiographic
assessment. Measurements obtained using an electrogoniometer were
less accurate and less reliable than those obtained with a plastic
goniometer, possibly because of the size and configuration of the
model used. Comparison of measurements from live animals and
carcasses revealed no significant differences between mean
measurements and suggested that further evaluation of carcasses as
a model for study of goniometry measurements in avian wing joints
should be considered.
Background:
· Goniometry is the measurement of ROM of a joint
· Methods: electrogoniometry, universal plastic goniometer,
measurement of joints in photos
· Radiographic measurements were used as the gold standard to
compare to
· Caution: It is possible to hyperextend joints and affect
measurements
Objective: Evaluate the accuracy of a plastic goniometer and
electrogoniometer compared to radiographic measurements of the
elbow and carpus of healthy barred owls under general
anesthesia.
Key Points:
· Plastic goniometer was accurate for elbow flexion and
extension and the carpal flexion
· Electrogoniometer was less accurate
Conclusion: Plastic goniometer was the most accurate device to
measure ROM of avian wing joints as compared to the gold standard
of radiographic measurements. Electrogoniometry was not
accurate.
Plastic goniometer ElectrogoniometerRadiographic assessment
Serratospiculosis in Captive Peregrine Falcons (Falco
peregrinus) in Switzerland
Ines B. Veiga, Marion Schediwy, Brigitte Hentrich, Caroline F.
Frey, Nelson Marreros,
Nadine Stokar-Regenscheit
Journal of Avian Medicine and Surgery 31(3):250–255, 2017
Taxonomy: Falconiformes (order) → Falconidae (family) → Falco
(genus)
Abstract: Infection with Serratospiculum species was identified
in a captive peregrine falcon (Falco peregrinus) in Switzerland.
Pathologic and parasitologic examination results revealed
generalized severe granulomatous airsacculitis, with intralesional
adults, larvae, and eggs of Serratospiculum species. Subsequently,
an individual coprological analysis of the remaining 15 falcons
(peregrine falcons and gyrfalcons [Falco rusticolus]) from the same
owner was performed. Eggs of Serratospiculum species (4 birds) and
Capillaria species (11 birds), and oocysts of Caryospora species (1
bird) were detected. Treatment with ivermection (2 mg/kg SC) was
effective, as none of the falcons excreted Serratospiculum species
eggs 10 days after one dose. To our knowledge, this is the first
report of infection with Serratospiculum species in captive falcons
in Europe.
Case: 8yo female peregrine falcon found dead
· Livered in a mixed group of privately owned gyrfalcons and
peregrine falcons
· Large number of nematodes found in coelomic cavity, thoracic
and abdominal air sacs, despite yearly ivermectin
· Air sacs were thickened and contained granulomas
· Identified Serratospiculum spp. by microscopic examination
· Visceral (pericardium, liver) and renal gout (not a direct
effect of nematodes)
· Four birds in the flock were positive on fecal examination and
shedding was stopped with ivermectin
Key Points:
· Serratospiculosis affects air sacs in many bird sps,
particularly in Falconidae family
· Causes respiratory signs and/or flight intolerance
· Life Cycle: Birds (host) eat infected beetles, grasshoppers,
woodlice, locusts (intermediate host) that are parasitized by
infective 3rd stage larvae → larvae penetrate proventriculus and
gizzard and migrate into the air sacs and lungs where they molt and
reach sexual maturity → eggs are regurgitated and swallowed and
then released into the environment in feces or pellets
· Anthelmintic drugs with effect against Serratospiculum:
fenbendazole, levamisole, mebendazole, moxidectin, thiabendazole,
melarsomine + ivermectin, and ivermectin
Conclusions: Serratospiculosis causes respiratory signs in birds
and is transmitted by ingestion of infected insects.
CLINICAL EFFECT OF HEMOPARASITE INFECTIONS IN SNOWY OWLS (BUBO
SCANDIACUS)
Kendra C. Baker, Christy L. Rettenmund, Samantha J. Sander E.
Rivas, Kaitlin C. Green, et. al.
Journal of Zoo and Wildlife Medicine, 49(1):143-152
Abstract:
Vector-borne hemoparasites are commonly found in avian species.
Plasmodium spp., the causative agent of avian malaria, are
intraerythrocytic parasites that can cause signs ranging from
subclinical infection to severe acute disease. In raptor species,
most hemoparasites are associated with subclinical infection and
are generally not treated when seen on blood evaluation. This case
series reviews five cases of hemoparasite infection in snowy owls
(Bubo scandiacus). These animals were infected with a variety of
hemoparasites, including Plasmodium, Haemoproteus, and
Leukocytozoon spp. Death of one of these birds due to hemoparasite
burden led to a change in the monitoring for and treatment of
subclinical hemoparasitic infections in this species. Three
subsequently infected snowy owls have been treated with primaquine
and chloroquine. The birds that were treated survived infection,
and parasite burdens in peripheral blood diminished. Postulated
reasons for increased morbidity and mortality associated with
hemoparasitic infections in captive snowy owls, as opposed to other
raptor species, include stress, concurrent disease, novel pathogen
exposure, and elevated environmental temperatures.
Summary:
Introduction:
· Plasmodium, Haemoproteus, and Leukocytozoon spp. -
vector-borne hemoparasites in birds
· wild passerines often reservoirs for hemoparasites
· not generally considered to be pathogenic in most passerine
and raptor species
· asymptomatic carriers, low morbidity and mortality despite
chronic parasitemia
· Plasmodium – P. relictum and P. elongatum common in North
America:
· transmitted via mosquitoes (Culicidae)
· exoerythrocytic stage - replication in host tissues
· erythrocytic phase - invasion of circulating blood cells
· prepatent (exoerythrocytic) acute (erythrocytic) crisis
chronic
· acute phase of infection - replication in host tissues leads
to inflammatory reaction and tissue necrosis, growth in RBC’s causes
hemolysis and anemia
· crisis stage - peak parasitemia
· chronic stage - parasitemia is adequately controlled by the
host immune system
· schizogony – asexual reproduction, occurs within host
· first 3 stages of schizogony can cause significant damage to
organs before it can be detected in blood
· Haemoproteus:
· transmitted via sand flies aka biting midges
(Ceratopogonidae)
· life cycle similar to plasmodium but schizogony is confined to
tissues
· Leukocytozoon:
· transmitted via black flies (Simulidae)
· life cycle similar to plasmodium but only gametocytes are
found in the blood in RBC and WBC’s
Cases:
· Case series of 5 SNOW housed at Maryland Zoo in Baltimore
describes the detection of hemoparasitic infections by blood smear
evaluation and PCR, pathology in 2 owls that died, and management
of 3 surviving cases
· Case 1 – 6yr F captive bred SNOW
· Found dead in enclosure
· Necropsy - disseminated protozoal infection with pericardial
effusion and pneumonia
· Case 2 – 1yr F SNOW
· Leukocytozoon, haemoproteus, and plasmodium on blood smear –
increased burden 1 month prior to death then decreased again
· Bird moved to another enclosure and 15 days later bird found
dying and arrested
· Necropsy – WNV was cause of death
· changes in spleen suggested protozoal parasitemia and ongoing
erythrocyte destruction contributed
· PCR positive for P. relictum
· Case 3 – 1yr F SNOW
· In enclosure with Case 2 when it died
· P. relictum and leukocytozoon found
· Treated with chloroquine and primaquine given rapid decline of
other birds – clear 3-4 weeks after treatment
· Recurrence 2.5 months later with P. relictum, Leukocytozoon,
Haemoproteus, and Babesia spp detected
· Bird released and recaptured and assessed 2 months after
release, no hemoparasites noted
· Case 4 – 4yr M SNOW
· Also housed with Case 2
· Plasmodium and leukocytozoon found in blood with mild
leukocytosis and lymphocytosis
· PCR positive for Haemoproteus syrnii
· Treated with chloroquine and primaquine
· Hemoparasite burden improved but leukocytosis and
lymphocytosis worsened
· Started itaconazole and another course of chloroquine and
primaquine started
· No hemoparasites noted after and bird did well
· Case 5 – 4yr F SNOW
· Also treated for hemoparasites but had lowest burden
(plasmodium and haemoproteus)
· Treated with chloroquine and primaquine
· PCR positive for P. relictum
· Found to be positive for Babesia spp. after several courses of
treatment
· Treated again with chloroquine and primaquine
· Low level of hemoparasites following treatments but bird did
well
Discussion:
· Arctic, Antarctic and island species believed to be more
susceptible to infection by hemoparasites, particularly
Plasmodium
· increases in parasite burden can an indicator of underlying
disease or disease severity
· hemoparasitic disease is not benign in SNOW’s as in other
raptors
· stressors likely exacerbated cases described – possibly heat
stress
· increased parasitemia occurred during warm weather
· Vector control, cooling, and reducing handling can be
implemented to decrease hemoparasitic disease
· Moving birds to new enclosures with new birds may have been a
contributing stressor
· Conflicting information exists of chronic impact of
hemiparasites in other species
· Gyrfalcons suspected to be more susceptible to Plasmodium
infection than other raptor species and show disease and mortality
with lower parasite loads, possibly due to stress in captivity
· Morphologic diagnosis along with PCR increases confidence in
diagnosis
· studies have shown that PCR alone can underestimate occurrence
of mixed infections
· Not all birds infected require treatment, low likelihood of
clearing infection
· Treat both stages of plasmodium
· chloroquine for blood stages
· primaquine for tissue stages
· mefloquine and doxycycline have also been used to treat
Plasmodium
· SNOW may be sensitivity to hemoparasite infections
· Exacerbated by stressors such as high seasonal temperatures,
close proximity to conspecifics, and stress related to medical
management in this paper
PRESUMED PHOTORECEPTOR DYSPLASIAS IN PEREGRINE FALCONS (FALCO
PEREGRINUS) AND PEREGRINE FALCON HYBRIDS
Bret A. Moore, Christopher J. Murphy, Annajane Marlar, Richard
R. Dubielzig, Leandro B. C. Teixeira, et. al.
Journal of Wildlife Diseases, 55(2):325-334
Abstract:
We describe a case series of photoreceptor dysplasia with
secondary retinal degeneration in juvenile Peregrine Falcons. Six
Peregrine Falcons (Falco peregrinus) and three Peregrine Falcon 3
Prairie Falcon (Falco mexicanus) hybrids had early-life visual
deficits. Eight birds had visual defects shortly after hatching,
and one bird had visual deficits first noticed at 5 mo of age.
Complete ophthalmic examinations were performed in each animal.
Eight of the animals had electroretinograms, and nine of the
animals had their eyes examined histologically after euthanasia.
Ophthalmic examinations did not reveal consistent and potentially
blinding abnormalities, including an absence of ophthalmoscopic
retinal lesions. Electroretinographic findings included subnormal
amplitudes (with rod responses more abnormal than cone responses),
with a negative b-wave amplitude occurring in one bird.
Histologically, a reduction in the number of photoreceptors was
present with numerous degenerative changes to the remaining
photoreceptors, including frequent blunting and disorganization of
photoreceptor outer segments, decreased numbers of cells in the
inner nuclear layer, decreased numbers of ganglion cells, decreased
thickness of the nerve fiber layer, and decreased myelinated axons
within the optic nerve. Ultrastructurally, only minor cone outer
segment changes and occasional phagocytic cells were seen. Results
strongly suggested a primary retinopathy, characterized by
photoreceptor dysplasia and secondary retinal degeneration with
loss of cellular elements throughout the retina. The presence of a
similar spectrum of findings in related individuals, the early age
of onset, and the relative lack of other environmental, ocular, or
systemic abnormalities suggested possible heritability.
Summary:
Introduction:
· Falcons have a greater cone density than humans
· Primary retinopathies rarely reported in birds
· occurs as retinal cell begins to differentiate (ex-
photoreceptor cells in photoreceptor dysplasia)
· can be early or late onset
· early onset primary photoreceptor retinopathy
· early visual deficits, severe photoreceptor structural
abnormalities, and rapid progression from further retinal
degeneration
· late onset primary photoreceptor retinopathy
· developmental abnormalities but variable onset of visual
deficits and rate of progression
· Secondary retinopathy – many reports on avian species
· characterized by photoreceptor degeneration following
apparently normal photoreceptor development and differentiation
· 9 PEFA and PEFA hybrids presented with visual deficits noted
shortly after hatch and diffuse bilateral retinal disease
Results/Discussion:
· 6 PEFA and 3 PEFA x PRFA hybrids presented for visual
deficits
· No sex predilection
· 3 birds were from same parents in two different clutches,
other birds unrelated
· case series suggests early onset vision loss from various
forms of a primary retinopathy is more likely than other causes
(nutritional, toxic, systemic disease, neoplastic, photic,
traumatic) in some falcons
· retinopathy is likely heritable and autosomal recessive
· heritable retinopathies documented in domestic chickens
· lack of documentation in wild raptors likely because they
don’t survive
· signs of retinal degeneration are more difficult to identify on
fundic exam in a non-tapetal fundus with anangiotic retinal pattern
– ERG’s are important for diagnosis in birds
· histo showed reduced rod and cone numbers, degenerative
changes to photoreceptor outer segments, and decrease in thickness
of other retinal layers
· ERG showed subnormal photoreceptor amplitudes in all cases
· one bird had negative ERG result - identifies inner retinal
dysfunction
· cases more closely resembled photoreceptor dysplasia than
either a retinal dysplasia or retinal degeneration
PREVALENCE AND RISK FACTORS OF TRICHOMONAS GALLINAE AND
TRICHOMONOSIS IN GOLDEN EAGLE (AQUILA CHRYSAETOS) NESTLINGS IN
WESTERN NORTH AMERICA
Benjamin M. Dudek, Michael N. Kochert, Joseph G. Barnes, Peter
H. Bloom, Joseph M. Papp, et. al.
Journal of Wildlife Diseases, 54(4):755-764
Abstract:
Avian trichomonosis, caused by the protozoan Trichomonas
gallinae, affects bird-eating raptors worldwide. Raptors can
develop trichomonosis by feeding on infected prey, particularly
Rock Pigeons (Columba livia), which are a reservoir for T.
gallinae. Raptors may be particularly vulnerable to T. gallinae
infection in degraded habitats, where changes in resources may
cause raptors to switch from foraging on native prey to
synanthropic avian species such as Rock Pigeons. Golden Eagles
(Aquila chrysaetos) typically forage on mammals; however, habitat
across much of their range is experiencing degradation through
changes in land use, climate, and human encroachment. In 2015, we
examined the prevalence of T. gallinae infection in Golden Eagle
nestlings across western North America and conducted an intensive
study on factors associated with T. gallinae infection and
trichomonosis in southwestern Idaho. We found T. gallinae infection
in 13% (12/96) of eagle nestlings across 10 western states and in
41% (13/32) of nestlings in southwestern Idaho. At the Idaho site,
the probability of T. gallinae infection increased as the
proportion of Rock Pigeons in nestling diet increased. Nestlings
with diets that consisted of 10% Rock Pigeons had a very high
probability of T. gallinae infection. We compared historical
(1971–81) and recent (2014–15) diet data and incidence of
trichomonosis lesions of nestling eagles in Idaho and found that
the proportion of Rock Pigeons in eagle diets was higher in recent
versus historical periods, as was the proportion of eagle nestlings
with trichomonosis lesions. Our results suggested that localized
shifts in eagle diet that result from habitat degradation and loss
of historical prey resources have the potential to affect Golden
Eagle nestling survival and supported the hypothesis that land use
change can alter biologic communities in a way that might have
consequences for disease infection and host susceptibility.
Summary:
Introduction:
· Avian trichomonosis - caused by flagellated protozoan parasite
Trichomonas gallinae
· commonly found in birds in the Columbidae family
· bird-eating raptors that feed on infected prey are susceptible
– often results in mortality
· primarily affects the upper GI of birds
· development of caseous lesions in the oropharynx
· can lead to starvation or suffocation
· naive populations can be severely effected
· high rates of infection found in raptors where loss of native
habitat and prey resulted in dietary shifts
· oral pH may affect risk of infection - persists at pH range of
6.5–7.5 but is less viable in more acidic conditions
· Oral pH of nestling COHA promotes infection but oral pH
decreases as hawks age, and adults are less susceptible to
infection
· Changes to western North American landscapes that have altered
prey availability for Golden Eagles, more likely to prey on rock
doves
· Study Objectives: document the prevalence of T. gallinae in
nestling GOEA, identify the factors associated with infection, and
examine whether infection risk has changed over time
· GOEA nestlings sampled throughout W North America during the
2015 breeding season to assess the geographic prevalence
· intensive study conducted in SW Idaho examined whether
nestling age, oral pH, or proportion of Rock doves in nestling diet
predicted T. gallinae infection rates
· historical (1971–81) and recent (2014–15) data used to examine
how nestling diet and incidence of trichomonosis have changed over
time at our Idaho study site
M+M:
· Oral swabs collected from nestling GOEA from 11 sites April to
June 2015 in western North America
· Samples examined under microscope for motile trichomonads
· DNA extraction and PCR also performed on samples
· Oropharynx of each nestling examined for lesions
· Birds with lesions were treated with carnidazole
· oral pH of 15 eagle nestlings measured every 8–10 days
throughout the nestling period at Idaho sites
· presence of lesions compared with historical (1971–81) data
documenting lesions
· sex also determined via DNA analysis with blood samples
· nestling diet also assessed by collecting prey remains and
pellets
· compared to historical (1971–81) diet data to see if increase
in rock doves
Results:
· Prevalence of T. gallinae in non-Idaho GOEA nestlings was
13%
· Prevalence in Idaho was higher - detected in 41% of nestlings
and 42% of nests had at least one nestling with positive
culture
· 18% of nests had at least one nestling that had a positive
culture
· presence of T. gallinae confirmed with PCR in 64% of
samples
· reoccurrence of oral lesions observed in 25% of treated
nestlings
· Mean nestling age when detected in culture: 23.5 +/- 11.0 d
(range 8–38 d)
· Mean age of oral lesion appearance: 30.3 +/- 13.5 d (range
12–49 d)
· Lesions developed 7.2 +/- 7.0 d after positive result via
culture
· Nestling age did not predict the probability of infection
· pH decreased with increasing age
· no significant relationship between infection and oral pH
· Proportion of Rock doves in diet predicted T. gallinae
infection
· Increased with more rock doves in diet
· 7% of unique diet items found to be rock doves
· Proportion of rock doves in diet of nestlings higher in
2014–15 compared to 1971–81
· Historically, 15% of nestlings had oral lesions compared to
41% in 2015
Discussion:
· High infection rates in Idaho associated with proportion of
Rock doves in nestling diet, which has increased significantly
compared to historical diets
· Possible reasons for lower prevalence at nest sites outside of
Idaho:
· Older nestlings sampled so may have missed infection and
mortality
· Diets include fewer rock doves
· Cultured swab samples and PCR results had a 53% agreement
· Trichomonads may have died in transport or possible low
density in samples
· Culturing swabs was a reliable indicator of the subsequent
development of trichomonosis
Documentation of T. gypaetinii - had pr VITAMIN B6 (PYRIDOXINE
HYDROCHLORIDE) TOXICOSIS IN FALCONS
Samour J, Perlman J, Kinne J, Baskar V, Wernery U, Dorrestein
G.
Journal of Zoo and Wildlife Medicine. 2016 Jun;47(2):601-8.
Abstract: This manuscript reports three independent accidental
cases of vitamin (Vit) B6 toxicosis in
gyrfalcons (Falco rusticolus) and peregrine falcons (Falco
peregrinus) and a toxicology study that was conducted to
characterize the clinical responses of gyrfalcons and gyrfalcon 3
peregrine falcons to a range of single intramuscular (IM) and oral
(PO) doses of Vit B6. Both lethal and nonlethal doses were
determined. Twelve female gyrfalcons died following IM injection of
1 ml of a vitamin B preparation. Within 30 min of injection, the
birds passed pistachio green-colored urates and progressed to
vomiting, anorexia, cessation of normal activity, ptosis, collapse,
and death, occurring 24–36 hr post injections. Three individuals
vomited frothy, partially digested blood and had clonic spasms and
convulsions. Postmortem and histopathology revealed multifocal
severe hepatic necrosis, splenic lymphoid tissue depletion and
hemorrhages with arterial necrosis, and acute renal tubular
necrosis. Following administration of a different, oral,
mineral-vitamin supplement, a total of 21 peregrine falcons in two
separate European facilities died suddenly. Histology of the liver
showed diffuse congestion and multifocal coagulative necrosis with
mild infiltration of heterophils. The particular nutritional
supplement, used by both breeders, was analyzed and found to
contain 5–9.7% Vit B6. Other randomly selected lots of the product
contained 0.007–0.27% Vit B6. According to the product label, Vit
B6 should have been present at 0.004%. To confirm the hypothesis
that Vit B6 was responsible for the deaths of the falcons in Abu
Dhabi, Vit B6 (British Pharmacopoeia [BP] grade) in powder form was
diluted in water for injection and administered IM to four groups
of falcons. Groups of four gyrfalcon3peregrine hybrid falcons or
gyrfalcons (or both) were given a single IM dose of 5, 10, 15, or
20 mg/kg of Vit B6 or received an oral dose of 25, 50, or 75 mg of
Vit B6. Only birds in the lowest dose groups survived. The maximum
nonlethal single doses of Vit B6 in falcons were 5 mg/kg i.m. and
25 mg/kg p.o.
Background:
· Vitamin B6 (pyridoxine) water soluble and part of Vit B
complex
· Vit B6: absorbed from diet appear in liver, converted into
pyridoxal 5-phosphate: metabolically active form, cofactor for
essential enzymes (birds/mammals).
· One other report of avian B6 toxicity in pigeons (but chickens
unaffected by same dose)
Key points:
· 3 accidental fatal toxicities of Vit B6 in peregrine and
gyrfalcons, IM and oral
· CS: green urates, vomiting. Path: liver/splenic necrosis,
acute renal tubular necrosis.
· Study of IM (5-20 mg/kg) and oral (25-75 mg/kg)
· All animals died except the lowest of the IM (5 mg/kg) and PO
(25 mg/kg) groups.
· Similar path as accidental cases. congestion and perivascular
hemorrhages of the lungs
· For many human formulations of B complex. If falcons are dosed
at 20mg/kg of Vit B1, they get 40mg/kg Vit B6 which is
lethal.
· B6= The highest single non-lethal dose is 5mg/kg IM and
25mg/kg PO, daily supplementation is likely lower.
· 200mg/kg kills pigeons but not chickens. Falcons were 8x are
more sensitive than pigeons.
Take home: Beware supplementing Vitamin B complex to birds,
20 mg/kg vitamin B1 may lead to lethal doses B6. In falcons see
lung, liver, splenic, renal pathology. The highest non-lethal
single doses were 5mg/kg IM, 25mg/kg PO. Avian species differences,
falcons most sensitive, then pigeons, chickens less.
Cloacal prolapse in raptors: review of 16 cases
Dutton TA, Forbes NA, Carrasco DC.
Journal of Avian Medicine and Surgery. 2016
Jun;30(2):133-41.
Abstract: Sixteen cases of cloacal prolapse in raptors were
reviewed in this study. Colonic prolapse was the most common
presentation (56% of cases). Red-tailed hawks (Buteo jamaicensis)
were overrepresented, comprising 66% of colonic prolapse cases. In
cases of colonic prolapse, postsurgical stricture formation was a
commonly identified complication after resection and anastomosis of
the colon. A novel technique was used in 2 cases of colonic
prolapse, in which sterile, semirigid rubber tubing was placed in
the distal colon and removed per-cloaca at the end of the
procedure; this facilitated a secure, fluid-tight anastomosis while
maintaining sufficient intestinal lumen. Oviductal prolapse (31% of
cases) was associated with the most guarded prognosis (40%
treatment success). Cloacoliths were treated successfully in 2
birds (13% of cases) by minimally invasive per-cloacal manual
removal.
Intro, M&M
· Cloacal prolapse in raptors is rare compared to clinical avian
practice
· 3 chambers of cloaca: coprodeum, urodeum, and proctodeum
· serves the digestive, urinary, and reproductive tracts.
· Sixteen cases of cloacal prolapse in raptors were reviewed in
this study
Results/Conclusion
· Colonic prolapse was the most common (56%), with red-tailed
hawks overrepresented (66%)-
· Enteritis most common cause – Campylobacter, coccidia
· Stricture of colon commonly seen complication of surgical
colonic R&A
· New technique: plastic tubing was used to maintain lumen
diameter, decreased stricture.
· Cases where anastomosis was performed caudal to cecal
remnant.
· Overall ~90% treatment success with colon prolapse.
· Cloacal prolapse due to cloacolith fixed easily, minimally
invasive
· Oviductal prolapse carried worse prognosis – 40% success.
Assoc with egg binging, peritonitis.
· Surgery typically performed.
Take home: Cloacal prolapse may be more common in raptors than
previously thought. Colonic most common and carries better
prognosis than oviduct. Redtail hawk overrepresented in this study.
Strictures are common following R& A and may be reduce with
tube technique.
DETERMINING RAPTOR SPECIES AND TISSUE SENSITIVITY FOR IMPROVED
WEST NILE VIRUS SURVEILLANCE
Kritzik KL, Kratz G, Panella NA, Burkhalter K, Clark RJ,
Biggerstaff BJ, Komar N.
Journal of Wildlife Diseases, 54(3), 2018, pp. 528–533
Abstract: Raptors are a target sentinel species for West Nile
virus (WNV) because many are susceptible to WNV disease, they are
easily sighted because of their large size, and they often occupy
territories near human settlements. Sick and dead raptors
accumulate at raptor and wildlife rehabilitation clinics. However,
investigations into species selection and specimen type for
efficient detection of WNV are lacking. Accordingly, we evaluated
dead raptors from north-central Colorado, US and southeast Wyoming,
US over a 4-yr period. Nonvascular mature feathers (‘‘quill’’),
vascular immature feathers (‘‘pulp’’), oropharyngeal swabs, cloacal
swabs, and kidney samples were collected from raptor carcasses at
the Rocky Mountain Raptor Program in Colorado from 2013 through
2016. We tested the samples using real-time reverse
transcriptase-PCR. We found that 11% (53/482) of raptor carcasses
tested positive for WNV infection. We consistently detected
positive specimens during a 12- wk span between the second week of
July and the third week of September across all years of the study.
We detected WNV RNA most frequently in vascular feather pulp from
Cooper’s Hawk (Accipiter cooperii). North American avian mortality
surveillance for WNV using raptors can obviate necropsies by
selecting Cooper’s Hawk and Red-tailed Hawk (Buteo jamaicensis) as
sentinels and targeting feather pulp as a substrate for viral
detection.
Intro
· Avian carcasses used to detect WNV activity and tissue
selection in raptors for surveillance is unknown
· Objective: sample carcasses for WNV and HPAIV RNA in selected
tissues
M&M:
· Samples submitted from dead raptors over 3 years within 48
hours of death.
· Samples: nonvascular feather quill, pulp from immature flight
feather, oropharyngeal swab, cloacal swab, kidney tissue.
· Reverse transcriptase PCR.
Results
· 11% of carcasses positive for WNV on at least one sample.
Cooper’s Hawk had the highest infected percentage
· Eleven species positive. High number of Swainson and red
tailed hawks in addition to Coopers
· Feather pulp was the most sensitive tissue for WNV RNA. Kidney
second.
· Feather pulp highest number of + in Coopers and Swainson’s
hawks
· Consistently tested positive from July to the end of
September
Discussion
· Cooper’s hawk good candidate for WNV surveillance among
raptors
· RTHA and Swainsons in the west coast also a good option
· Most sensitive tissue type was the feather pulp
· Similar findings in corvid carcasses. However vascular tissue
is not always available
· If necropsies performed, kidney tissue can be used as a
substitute
· eviously only been reported in Old World vultures
· If GOEA nestling diets consisted of >10% Rock doves, then
nestlings had a high probability of T. gallinae infection