OBJECTIVE To describe qualitative blinking patterns and determine quantitative kinematic variables of eyelid motion in ophthalmologically normal horses.
ANIMALS 10 adult mares.
PROCEDURES High-resolution videography was used to film blinking behavior. Videotapes were analyzed for mean blink rate, number of complete versus incomplete blinks, number of unilateral versus bilateral blinks, and subjective descriptions of blinking patterns. One complete blink for each horse was analyzed with image-analysis software to determine the area of corneal coverage as a function of time during the blink and to calculate eyelid velocity and acceleration during the blink.
RESULTS Mean ± SD blink rate was 18.9 ± 5.5 blinks/min. Blinks were categorized as minimal incomplete (29.7 ± 15.6%), moderate incomplete (33.5 ± 5.9%), complete (30.8 ± 13.1%), and complete squeeze (6.0 ± 2.8%); 22.6 ± 9.0% of the blinks were unilateral, and 77.3 ± 9.1% were bilateral. Mean area of exposed cornea at blink initiation was 5.89 ± 1.02 cm2. Mean blink duration was 0.478 seconds. Eyelid closure was approximately twice as rapid as eyelid opening (0.162 and 0.316 seconds, respectively). Deduced maximum velocity of eyelid closure and opening was −16.5 and 7.40 cm/s, respectively. Deduced maximum acceleration of eyelid closure and opening was −406.0 and −49.7 cm/s2, respectively.
CONCLUSIONS AND CLINICAL RELEVANCE Kinematic variables of ophthalmologically normal horses were similar to values reported for humans. Horses had a greater percentage of complete squeeze blinks, which could increase tear film stability. Blinking kinematics can be assessed as potential causes of idiopathic keratopathies in horses.
To document ocular findings in cats with blastomycosis.
35 cats with blastomycosis.
Medical records from 1978 through 2019 were reviewed to identify cats with confirmed Blastomyces infection. Cats were grouped as having or not having ocular involvement. Clinical signs, histopathologic findings, and response to treatment were evaluated.
21 of the 35 (60%) cats with confirmed blastomycosis had ocular abnormalities. Two of 21 cats with ocular abnormalities also had systemic hypertension and were excluded. Of the remaining 19 cats, 15 (79%) had bilateral ocular signs. Ten (53%) cats had inflammatory ocular lesions, and 9 (47%) had neuro-ophthalmic abnormalities. Six of the 19 (32%) cats appeared to be completely blind, and 5 (26%) appeared to be unilaterally blind. For the 10 cats with inflammatory ocular lesions, the most common lesions were anterior uveitis (9/20 eyes), active chorioretinitis (6/20 eyes), and retinal detachment (4/20 eyes). For the 9 cats with neuro-ophthalmic abnormalities, the most common abnormalities were a negative menace or tracking response (10/18 eyes) and negative pupillary light response (4/18 eyes).
Results suggested that ocular involvement is common in cats with blastomycosis and that both inflammatory lesions and neuro-ophthalmic abnormalities can be seen. Blastomycosis should be considered in the differential diagnosis for cats with anterior uveitis, posterior segment inflammation, or neuro-ophthalmic abnormalities, and a complete ophthalmic examination should be performed in all cats with confirmed or suspected blastomycosis.
Objective—To determine whether pharmacokinetic
analysis of data derived from a single IV dose of
iohexol could be used to predict creatinine clearance
and evaluate simplified methods for predicting serum
clearance of iohexol with data derived from 2 or 3
blood samples in clinically normal foals.
Animals—10 healthy foals.
Procedure—Serum disposition of iohexol and exogenous
creatinine clearance was determined simultaneously
in each foal (5 males and 5 females). A 3-compartment
model of iohexol serum disposition was
selected via standard methods. Iohexol clearance calculated
from the model was compared with creatinine
clearance. Separate limited-sample models were
created with various combinations of sample times
from the terminal slope of the plasma versus time
profile for iohexol. Correction factors were determined
for the limited-sample models, and iohexol
clearance calculated via each method was compared
with exogenous creatinine clearance by use of
method comparison techniques.
Results—Mean exogenous creatinine clearance was
2.17 mL/min/kg. The disposition of iohexol was best
described by a 3-compartment open model. Mean
clearance value for iohexol was 2.15 mL/min/kg and
was not significantly different from mean creatinine
clearance. A method for predicting serum iohexol
clearance based on a 2-sample protocol (3- and 4-hour
samples) was developed.
Conclusions and Clinical Relevance—Iohexol clearance
can be used to predict exogenous creatinine
clearance and can be determined from 2 blood samples
taken after IV injection of iohexol. Appropriate
correction factors for adult horses and horses with
abnormal glomerular filtration rate need to be determined.
(Am J Vet Res 2003;64:1486–1490)
Objective—To determine whether antibodies against
Sarcocystis neurona could be detected in CSF from
clinically normal neonatal (2 to 7 days old) and young
(2 to 3 months old) foals.
Animals—15 clinically normal neonatal Thoroughbred
Procedure—Serum and CSF samples were obtained
from foals at 2 to 7 days of age and tested for antibodies
against S neurona by means of western blotting.
Serum samples from the mares were also tested
for antibodies against S neurona. Additional CSF
and blood samples were obtained from 5 foals
between 13 and 41 days after birth and between 62
and 90 days after birth.
Results—Antibodies against S neurona were detected
in serum from 13 mares and their foals; antibodies
against S neurona were detected in CSF from 12 of
these 13 foals. Degree of immunoreactivity in serum
and CSF decreased over time, and antibodies against
S neurona were no longer detected in CSF from 2
foals 83 and 84 days after birth. However, antibodies
could still be detected in CSF from the other 3 foals
between 62 and 90 days after birth.
Conclusions and Clinical Relevance—Results indicate
that antibodies against S neurona can be detected
in CSF from clinically normal neonatal (2 to 7 days
old) foals born to seropositive mares. This suggests
that western blotting of CSF cannot be reliably used
to diagnose equine protozoal myeloencephalitis in
foals < 3 months of age born to seropositive mares.
(J Am Vet Med Assoc 2002;220:208–211)
Objective—To evaluate antiplatelet effects and pharmacodynamics
of clopidogrel in cats.
Animals—5 purpose-bred domestic cats.
Procedure—Clopidogrel was administered at dosages
of 75 mg, PO, every 24 hours for 10 days; 37.5 mg, PO,
every 24 hours for 10 days; and 18.75 mg, PO, every
24 hours for 7 days. In all cats, treatments were
administered in this order, with at least 2 weeks
between treatments. Platelet aggregation in response
to ADP and collagen and oral mucosal bleeding times
(OMBTs) were measured before and 3, 7, and 10 days
(75 and 37.5 mg) or 7 days (18.75 mg) after initiation of
drug administration. Serotonin concentration in plasma
following stimulation of platelets with ADP or collagen
was measured before and on the last day of
drug administration. Platelet aggregation, OMBT, and
serotonin concentration were evaluated at various
times after drug administration was discontinued to
determine when drug effects were lost.
Results—For all 3 dosages, platelet aggregation in
response to ADP, platelet aggregation in response to
collagen, and serotonin concentration were significantly
reduced and OMBT was significantly increased
at all measurement times during drug administration
periods. All values returned to baseline values by 7
days after drug administration was discontinued. No
significant differences were identified between
doses. None of the cats developed adverse effects
associated with drug administration.
Conclusions and Clinical Relevance—Results suggest
that administration of clopidogrel at dosages
ranging from 18.75 to 75 mg, PO, every 24 hours,
results in significant antiplatelet effects in cats. (J Am Vet Med Assoc 2004;225:1406–1411)
Case Description—A 7-month-old 16.6-kg (36.5-lb) sexually intact female Golden Retriever was evaluated because of progressive severe bilateral membranous conjunctivitis, oral lesions, nasal discharge, and cough.
Clinical Findings—Histologic examination of conjunctival biopsy specimens revealed findings consistent with ligneous conjunctivitis. Circulating plasminogen activity was repeatedly low, and congenital plasminogen deficiency was identified as the underlying cause of the ocular, oral, and respiratory lesions.
Treatment and Outcome—Topical and subconjunctival administrations of fresh frozen plasma (FFP), topical administration of cyclosporine, and oral administration of azathioprine had no effect on the conjunctival membranes. Excision of the membranes followed by intensive treatment with topical applications of heparin, tissue plasminogen activator, corticosteroid, and FFP and IV administration of FFP prevented membrane regrowth. Intravenous administration of FFP increased plasma plasminogen activity to within reference limits, improved respiratory and oral lesions, and resulted in weight gain; discontinuation of this treatment resulted in weight loss, signs of depression, and worsening of lesions. After euthanasia because of disease progression, necropsy findings included mild hydrocephalus; multifocal intestinal hemorrhages; and fibrinous plaques in the oral cavity, nasopharynx, trachea, esophagus, and pericardium. Microscopically, the plaques were composed of fibrin and poorly organized granulation tissue. Fibrin thrombi were present within vessels in the lungs, oral cavity, and trachea.
Clinical Relevance—In dogs, congenital plasminogen deficiency can occur and may be the underlying cause of ligneous conjunctivitis. A combination of surgical and medical treatments may improve conjunctival membranes, and administration of FFP IV appears to be effective in treating nonocular signs of plasminogen deficiency.