Objective—To characterize the temporality of dates
of breeding and abortion classified as mare reproductive
loss syndrome (MRLS) among mares with abortions
during early gestation.
Animals—2,314 mares confirmed pregnant at
approximately 28 days after breeding from 36 farms in
central Kentucky, including 515 mares that had earlyterm
Procedure—Farm veterinarians and managers were
interviewed to obtain data for each mare that was
known to be pregnant to determine pregnancy status,
breeding date, last date known to be pregnant, and
date of abortion.
Results—Mares bred prior to April 1, 2001,
appeared to be at greatest risk of early-term abortion,
both among and within individual farms.
Mares bred in mid-February appeared to be at
greatest risk of abortion, with an estimated weekly
incidence rate of abortion of 66% (95% CI, 52% to
Conclusions and Clinical Relevance—Mares in
central Kentucky bred between mid-February and
early March were observed to be at greatest risk of
early-term abortion, and risk gradually decreased to
a background incidence of abortion of approximately
11%. Mares bred after April 1, 2001, appeared to
be at markedly less risk, indicating that exposure to
the cause of MRLS likely occurred prior to this
date. (Am J Vet Res 2005;66:1792–1797)
Objective—To test the ability of a single injection of a
sustained-release formulation of moxidectin (moxidectin
SR) to protect dogs against heartworm infection
for 180 days after inoculation with infective thirdstage
larvae (L3) of Dirofilaria immitis.
Animals—32 adult mixed-breed dogs.
Procedure—Dogs were allocated to 4 groups on the
basis of weight and sex. Dogs were injected SC with
saline (0.9% NaCl) solution or moxidectin SR at the
rate of 0.06, 0.17, or 0.5 mg/kg of body weight (day 0).
Each dog was inoculated SC with 50 D immitis L3 180
days later. On days 330 and 331, dogs were euthanatized.
The heart, lungs, and thoracic cavity were examined,
and number and sex of heartworms were determined.
Results—A mean of 35.9 heartworms was recovered
from untreated control dogs. Fourteen worms were
recovered from 1 of 8 dogs given moxidectin SR at the
lowest dosage, and none of the dogs in the 2 highest
moxidectin treatment groups were infected. Small
barely palpable granulomas were detected at injection
sites of moxidectin-treated dogs. Frequency and size of
granulomas were positively correlated with dose of
Conclusions and Clinical Relevance—A single dose
of moxidectin SR at a dosage as low as 0.17 mg/kg
can safely and reliably confer complete protection
against infection after challenge-exposure with
D immitis L3, and protection lasts for at least 180
days. This mode of prophylactic treatment against
infection with heartworms effectively eliminates failure
of prophylaxis that results from erratic administration
of medications designed for monthly administration.
(Am J Vet Res 2001;62:1721–1726)
CASE DESCRIPTION An adult sexually intact female Harris hawk (Parabuteo unicinctus) housed at a wildlife hospital was evaluated because of acute collapse during an educational exhibition.
CLINICAL FINDINGS Physical examination and hematologic analysis revealed no abnormalities; radiography revealed findings consistent with a previous tibiotarsal fracture. Coelioscopy with histologic examination and fungal culture of lung and air sac samples revealed anthracosis but no fungal infection. The hawk was discharged and temporarily removed from the education program; 1 month later, upon reintroduction into the program, it collapsed again. Physical examination and hematologic findings were similar to those after the first episode. Transcoelomic and transesophageal echocardiography and CT angiocardiography findings were consistent with cardiomyopathy.
TREATMENT AND OUTCOME Initial cardiac treatment included furosemide (0.5 mg/kg [0.23 mg/lb], PO, q 24 h) and pimobendan (10 mg/kg [4.5 mg/lb], PO, q 12 h). After 10 days of treatment, peak and trough plasma concentrations of pimobendan were measured at 25, 196 and 715.97 ng/mL, respectively; the dosage was decreased to 0.25 mg/kg (0.11 mg/lb), PO, every 12 hours. No overt signs of toxicosis were detected. A sample was collected to reevaluate plasma pimobendan concentration after 30 days of treatment; results were not obtained prior to the patient's death but revealed a peak concentration of 16.8 ng/mL, with an undetectable trough concentration. The hawk was found dead 6 months after initial evaluation. Necropsy revealed cardiomegaly, but histologic examination did not reveal an inciting cause of cardiac dysfunction.
CLINICAL RELEVANCE Cardiac disease in raptors may be underreported. Transcoelomic and transesophageal echocardiography and CT angiography provided useful information for the diagnosis of cardiac disease in the hawk of this report.
Objective—To identify factors associated with abortions
during early gestation classified as mare reproductive
loss syndrome (MRLS).
Animals—324 broodmares from 43 farms in central
Kentucky, including 121 mares from 25 farms that
had early-term abortions (ETAs) associated with
MRLS (case horses), 120 mares from the same farms
but that did not abort, and 83 mares from 18 farms
that were not severely impacted by MRLS.
Procedure—Farm managers were interviewed to
obtain data on various management practices and
environmental exposures for the mares. Data for case
and control horses were compared to identify risk factors
for mares having MRLS-associated ETAs.
Results—Several factors increased the risk of MRLS-associated
ETAs, including feeding hay in pasture,
greater than usual amounts of white clover in pastures,
more eastern tent caterpillars in pastures, abortion
during a previous pregnancy, and sighting deer or
elk on the premises.
Conclusions and Clinical Relevance—Analysis indicates
that certain characteristics of pastures predisposed
mares to MRLS-associated ETAs. Methods for
limiting exposure to pasture (keeping mares in stalls
longer) during environmental conditions similar to
those of 2001 (ie, sudden freezing in mid-April following
warmer-than-usual springtime temperatures and
larger-than-usual numbers of eastern tent caterpillars
in and around pastures) should reduce the risk of
mares having MRLS-associated ETAs. It was not possible
to determine whether exposure to white clover
or caterpillars were causal factors for MRLS or were
merely indicators of unusual environmental conditions
that resulted in exposure of mares to a toxic or infectious
agent. (J Am Vet Med Assoc 2003;222:210–217)
Case Description—A 5-month-old captive female striped skunk (Mephitis mephitis) was evaluated because of lethargy, signs of depression, azotemia, and erythema of the skin around the eyes.
Clinical Findings—Antemortem diagnostic tests revealed renal disease but failed to identify an etiologic agent. A diagnosis of severe nonsuppurative interstitial nephritis was made on the basis of results of histologic examination of renal biopsy specimens.
Treatment and Outcome—The skunk was administered isotonic fluids SC daily and later every other day because of the handling-related stress. Because of the skunk's deteriorating condition, it was euthanized after 24 days of supportive care. Aleutian disease was diagnosed on the basis of positive results of a PCR assay that targeted the DNA from Aleutian disease virus (ADV); positive results for ADV were also obtained by use of plasma counterimmunoelectrophoresis and an ELISA. Genetic sequencing of the 365-base pair PCR product revealed 90% sequence identity with mink ADV.
Clinical Relevance—In the skunk of this report, infection with a skunk-specific parvovirus resulted in clinical signs and pathologic changes similar to those associated with ADV infection in mink. For skunks with signs of renal failure, differential diagnoses should include parvovirus infection. In confirmed cases of infection with this ADV-like virus, appropriate quarantine and biosecurity measures should be in place to prevent spread to other susceptible animals within a zoological collection.