Objective—To develop a reverse transcriptase-polymerase
chain reaction (RT-PCR) assay to detect feline
herpesvirus-1 (FHV-1) latency-associated transcripts
(LATs) in the corneas and trigeminal ganglia of cats
that did not have clinical signs of ocular disease.
Sample Population—Corneas and trigeminal ganglia
obtained from 21 cats necropsied at the Indiana
Animal Disease Diagnostic Laboratory and 25 cats
euthanatized at a humane shelter; none of the cats
had a recent history of respiratory tract or ocular disease,
and all had normal results for ophthalmic examinations.
Procedure—Both corneas and both trigeminal ganglia
were harvested from each cat. An initial PCR assay
detected FHV-1 DNA in the corneas and trigeminal
ganglia. The RNA was then isolated from samples
positive for FHV-1 DNA, and an RT-PCR assay was
used to detect LATs.
Results—FHV-1 DNA was detected in 45 of 92
(48.9%) corneas and 38 of 92 (41.3%) trigeminal ganglia.
In many samples, the RNA had degraded and RTPCR
assay was not possible. Of the samples subjected
to RT-PCR assay, none of the 39 corneas but 4 of
16 trigeminal ganglia had positive results when tested
Conclusions and Clinical Relevance—Analysis of
the results indicated that a high percentage of cats
that did not have clinical signs of ocular disease had
detectable FHV-1 DNA in their corneas and trigeminal
ganglia. This study documents that the RT-PCR assay
can successfully identify LATs and may serve as a
tool to better understand the biologic characteristics
of FHV-1 and its relationship to clinical disease. ( Am J Vet Res 2004;65:314–319)
Objective—To determine whether oral administration
of L-lysine to cats would lessen the severity of conjunctivitis
caused by feline herpesvirus (FHV-1).
Animals—8 healthy young adult cats.
Procedure—Cats received oral administration of
lysine monohydrochloride (500 mg, q 12 h) or placebo
(lactose) beginning 6 hours prior to inoculation of
virus. The left conjunctival sac received a 50-µl suspension
of FHV-1 grown in cell culture (1.8 X 108 tissue
culture infective dose50) on day 1. Cats were evaluated
and scores given for clinical signs each day for 21
days. Samples for virus isolation were collected from
the eye and throat every third day. Plasma lysine and
arginine concentrations were measured prior to the
study and on days 3, 14, and 22.
Results—Cats that received lysine had less severe
conjunctivitis than cats that received placebo. Virus
isolation results did not differ between the groups.
Plasma lysine concentration was significantly higher
in cats that received lysine, compared with control
cats, whereas plasma arginine concentrations did not
differ between groups.
Conclusion and Clinical Relevance—Oral administration
of 500 mg of lysine to cats was well tolerated
and resulted in less severe manifestations of conjunctivitis
caused by FHV-1, compared with cats that
received placebo. Oral administration of lysine may be
helpful in early treatment for FHV-1 infection by lessening
the severity of disease. (Am J Vet Res
Objective—To determine whether the tears of llamas,
sheep, and cattle contain lysozyme and compare
lysozyme concentrations in tears among these
Animals—40 llamas, 5 sheep, and 36 cattle.
Procedure—Electrophoresis, western blot immunoassay
for lysozyme, a spectrophotometric assay to
detect tear lysozyme by its ability to lyse a suspension
of Micrococcus lysodeiticus, and a microtiter
plate colorometric assay were performed.
Results—A 13.6-kd protein band was detected by
use of electrophoresis and western blot immunoassay
in llama and sheep tears but not cattle tears.
Results of spectrophotometric assay suggested that
llama and sheep tears had high concentrations of
lysozyme, whereas cattle tears had low concentrations.
Results of the microtiter plate colorometric
assay suggested that llama tears had high concentrations
of lysozyme, whereas concentrations in sheep
and cattle tears were lower.
Conclusions and Clinical Relevance—Lysozyme
concentrations in tears may vary among species and
this variability may contribute to differing susceptibilities
to ocular diseases such as infectious keratoconjunctivitis.
(Am J Vet Res 2000;61:1294–1297)
Objective—To evaluate the effect of topical application
of a 1% morphine sulfate solution (MSS) on signs
of pain and wound healing in dogs with corneal ulcers
and examine normal corneas immunohistochemically
for the presence of µ and δ opioid receptors.
Procedure—A 7-mm superficial corneal ulcer was
surgically created in the right eye (OD) of 10 dogs,
after which gentamicin solution and 1% MSS (n = 6)
or saline solution (4) was administered topically OD 3
times daily. Blepharospasm, tearing, conjunctival
hyperemia, aqueous flare, esthesiometer readings,
and pupil size were recorded before and 30 minutes
after treatment in all dogs. Ulcer size and days to
completion of healing were recorded. Corneas from 4
treated and 3 control dogs were evaluated histologically.
Normal canine corneas from 2 dogs not used in
the study were evaluated immunohistochemically for
the presence of µ and δ opioid receptors.
Results—Dogs treated with MSS had significantly
less blepharospasm and lower esthesiometer readings
than did control dogs. Duration of ulcer healing
and findings of histologic evaluation of corneas did
not differ between groups. Numerous δ and infrequent
µ opioid receptors were identified in the
corneal epithelium and anterior stroma of normal
Conclusions and Clinical Relevance—Topical use of
1% MSS in dogs with corneal ulcers provided analgesia
and did not interfere with normal wound healing.
Both µ and δ opioid receptors were identified in normal
corneas of dogs, although the µ receptors were
present only in small numbers. (Am J Vet Res 2003;64:813–818)
Objective—To evaluate the in vitro antifungal properties of silver sulfadiazine (SSD) and natamycin against filamentous fungi isolated from eyes of horses with keratomycosis.
Sample Population—Filamentous fungal isolates obtained from eyes of keratomycosis-affected horses.
Procedures—Fungal culture of ocular samples yielded 6 Fusarium spp; 7 Aspergillus spp; and 1 isolate each of Curvularia, Scopulariopsis, Penicillium, and Chrysosporium. For each fungal isolate, minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of SSD and natamycin were determined.
Results—For all 17 fungal isolates, SSD MIC distribution ranged from ≤ 1 to > 64 μg/mL; MIC50 and MIC90 (MICs at which 50% and 90% of organisms were inhibited) were 4 and 32 μg/mL, respectively. The SSD MFC distribution for all isolates was ≤ 1 to > 64 μg/mL; MFC50 and MFC90 (MFCs at which 50% and 90% of organisms were killed) were 8 and > 64 μg/mL, respectively. For all fungal isolates, natamycin MIC distribution ranged from 256 to > 1,000 μg/mL; MIC50 and MIC90 were 512 and > 1,000 μg/mL, respectively. The natamycin MFC distribution for all isolates ranged from 512 to > 1,000 μg/mL; MFC50 and MFC90 were each > 1,000 μg/mL.
Conclusions and Clinical Relevance—These in vitro data suggest that SSD is fungicidal against the fungal isolates that were obtained from eyes of horses with keratomycosis and that natamycin is fungicidal against some of the isolates at the drug concentrations evaluated. Silver sulfadiazine may be a therapeutic option for equine keratomycosis.
Objective—To determine the effect of eyelid manipulation and manual jugular compression on intraocular pressure (IOP) measurement in clinically normal dogs.
Design—Randomized clinical trial.
Animals—30 dogs (57 eyes) without diseases or medications that affect IOP.
Procedures—An applanation tonometer was used to measure IOP during eyelid manipulation or jugular compression. Six manipulations were used in each eye, including minimal eyelid manipulation, maximal dorsoventral extension of the eyelids, lateral eyelid extension, manual compression of the ipsilateral jugular vein, manual compression of both jugular veins, and lateral eyelid extension with manual compression of both jugular veins. Skull type and position of globe in the orbit were recorded.
Results—The 2 manipulations that caused the greatest significant increase in mean IOP were lateral eyelid extension with compression of both jugular veins (difference from baseline IOP, 17.6 mm Hg; 95% confidence interval [CI], 15.7 to 19.5 mm Hg) and lateral eyelid extension alone (16.5 mm Hg; 95% CI, 14.6 to 18.4 mm Hg). Dorsoventral eyelid extension (6.42 mm Hg; 95% CI, 4.5 to 8.3 mm Hg) and compression of both jugular veins alone (3.0 mm Hg; 95% CI, 1.1 to 5.0 mm Hg) significantly increased mean IOP, compared with baseline. Compression of the ipsilateral jugular vein increased mean IOP (0.3 mm Hg; 95% CI, −1.6 to 2.2 mm Hg) from baseline, but not significantly.
Conclusions and Clinical Relevance—Traction on the eyelids or pressure on both jugular veins can significantly increase IOP values as measured by use of applanation tonometry in clinically normal dogs.
Objective—To report values for tear production, central corneal touch threshold (CTT), and intraocular pressure (IOP) in healthy guinea pigs and determine results of aerobic bacterial culture and cytologic examination of conjunctival swab specimens.
Animals—31 healthy guinea pigs (62 eyes) of various ages and breeds.
Procedures—Tear production was measured by the phenol red thread tear test (PRT) and Schirmer tear test (STT) before and after topical anesthetic application, CTT was measured with an esthesiometer, and IOP was measured by applanation tonometry.
Results—Combining data from all eyes, mean ± SD PRT values before and after topical anesthetic administration were 21.26 ± 4.19 mm/15 s and 22.47 ± 3.31 mm/15 s, respectively, and mean IOP was 18.27 ± 4.55 mm Hg. Median STT values before and after topical anesthetic administration were 3 mm/min (range, 0 to 12 mm/min) and 4 mm/min (range, 0 to 11 mm/min), respectively, and median CTT was 2.0 cm (range, 0.5 to 3.0 cm). Values did not differ between eyes for any test, but significant differences were identified for PRT values between males and females and between values obtained before and after topical anesthetic administration. Common bacterial isolates included Corynebacterium spp, Streptococcus spp, and Staphylococcus spp. Cytologic examination of conjunctival swab specimens revealed mainly basal epithelial cells; lymphocytes were common.
Conclusions and Clinical Relevance—Results provided information on values for PRT, STT, CTT, and IOP in healthy guinea pigs and on expected findings for aerobic bacterial culture and cytologic examination of conjunctival swab specimens.
Objectives—To determine whether aqueous humor
flare, measured by use of laser flaremetry, was proportional
to aqueous humor protein concentration and
to use laser flaremetry to evaluate disruption of the
blood-aqueous barrier (BAB) in cats.
Animals—30 healthy adult cats.
Procedure—Laser flaremetry values for all eyes were
compared with aqueous humor protein concentrations
determined by use of a Coomassie blue microprotein
assay. Laser flaremetry was then performed
on both eyes before (0 hours) and 4, 8, and 26 hours
after initiation of topical application of 2% pilocarpine
(q 8 h) to 1 eye of 9 cats or paracentesis of the anterior
chamber of 1 eye of 8 cats. Intraocular pressure
and pupil size were also determined. Aqueous humor
protein concentration was extrapolated from flare values
by use of linear regression.
Results—There was a linear relationship between
flare values and aqueous humor protein concentrations.
Topical application of 2% pilocarpine and paracentesis
of the anterior chamber caused a breakdown
of the BAB that was detected by use of laser flaremetry.
The highest mean flare readings after application
of pilocarpine or paracentesis were 24.4 and 132.8
pc/ms, respectively, which corresponded to aqueous
humor protein concentrations of 85.5 and 434.9
Conclusions and Clinical Relevance—Paracentesis of
the anterior chamber resulted in a more severe breakdown
of the BAB in cats than topical application of 2%
pilocarpine. Laser flaremetry may be a useful clinical
method to detect increases in aqueous flare and,
hence, disruptions of the BAB in cats. (Am J Vet Res
Objective—To analyze and compare contents of the
preocular tear films of llamas and cattle.
Animals—40 llamas and 35 cattle.
Procedure—Tear pH was determined by use of a pH
meter. Total protein concentration was determined by
use of 2 microtiter methods. Tear proteins were separated
by use of electrophoresis and molecular
weights of bands were calculated. Western blot
immunoassay was used to detect IgA, lactoferrin,
transferrin, ceruloplasmin, α1-antitrypsin, α1-amylase,
and α2-macroglobulin. Enzyme electrophoresis was
used to detect proteases.
Results—The pH of llama and cattle tears were 8.05
± 0.01 and 8.10 ± 0.01, respectively. For results of
both methods, total protein concentration of llama
tears was significantly greater than that of cattle
tears. Molecular weights of tear protein bands were
similar within and between the 2 species, although
llama tears had a distinct 13.6-kd band that was not
detected in cattle. Lactoferrin, IgA, transferrin, ceruloplasmin,
α1-antitrypsin, α1-amylase, α2–macroglobulin,
and proteases were detected in both species.
Conclusions and Clinical Relevance—Llama tears
have significantly greater total protein concentration
than cattle tears, whereas pH is similar between
species. Because little variation was detected within
species for the number and molecular weight of protein
bands, pooling of tears for analysis is justified.
Results suggest that lactoferrin, ceruloplasmin, transferrin,
α1-antitrypsin, α2-macroglobulin, α1-amylase,
and IgA are present in the tears of llamas and cattle.
(Am J Vet Res 2000;61:1289–1293)