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Abstract

OBJECTIVE To evaluate the tear film osmolality and electrolyte composition in healthy horses.

ANIMALS 15 healthy adult horses.

PROCEDURES Each horse was manually restrained, and an ophthalmic examination, which included slit-lamp biomicroscopy, indirect ophthalmoscopy, and a Schirmer tear test, was performed. Tear samples were collected from both eyes with microcapillary tubes 3 times at 5-minute intervals. The tear samples for each horse were pooled, and the osmolality and electrolyte concentrations were measured. The mean (SD) was calculated for each variable to establish preliminary guidelines for tear film osmolality and electrolyte composition in healthy horses.

RESULTS The mean (SD) tear film osmolality was 283.51 (9.33) mmol/kg, and the mean (SD) sodium, potassium, magnesium, and calcium concentrations were 134.75 (10), 16.3 (5.77), 3.48 (1.97), and 1.06 (0.42) mmol/L, respectively. The sodium concentration in the tear film was similar to that in serum, whereas the potassium concentration in the tear film was approximately 4.75 times that of serum.

CONCLUSIONS AND CLINICAL RELEVANCE Results provided preliminary guidelines with which tear samples obtained from horses with keratopathies can be compared. Measurement of tear film osmolality in these horses was easy and noninvasive. The tear film concentration of divalent cations was greater than expected and was higher than the divalent cation concentrations in the tear films of rabbits and humans. These data may be clinically useful for the diagnosis and monitoring of hyperosmolar ocular surface disease in horses.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine magnitude and duration of the effect of oral administration of methazolamide at 2 dosages on intraocular pressure (IOP) in dogs in single- dose and multiple-dose trials and to determine aqueous humor flow rate (AHFR) by use of anterior segment fluorophotometry before and during treatment.

Animals—25 healthy adult Beagles.

Procedure—Baseline IOPs and AHFRs were determined on days 0 and 1, respectively. On day 2, the single-dose trial was initiated with oral administration of 25 or 50 mg of methazolamide at 7 AM to 2 groups of 10 dogs each. Five dogs served as controls. In the multiple-dose trial, the same dogs received 25 or 50 mg of methazolamide at 7 AM and at 3 and 11 PM on days 3 through 9.

Results—Intraocular pressures varied diurnally with highest IOPs in the morning. In the single-dose trial, IOP decreased significantly at 3 to 6 hours after treatment and then increased significantly at later time points, compared with baseline values. In the multipledose trial, dogs in both treatment groups had significantly lower IOPs during the treatment period at 10 AM and 1 PM but not at 6 and 9 PM, compared with baseline values. In both treatment groups morning IOPs had returned to baseline values by the first day after treatment. Evening IOPs were significantly increased by 2 to 3 days after treatment, compared with baseline values. The AHFRs in both treatment groups were significantly lower than pretreatment AHFRs.

Conclusions and Clinical Relevance—Oral administration of methazolamide decreases IOPs and AHFRs in clinically normal dogs, with effectiveness diminishing in the evening. (Am J Vet Res 2003;64:183–187)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To characterize Pasteurella spp isolated from healthy pack goats and evaluate the effects of administration of a commercial Pasteurellavaccine.

Animals—45 goats.

Procedure—Pharyngeal swab specimens and blood samples were collected on day 0 before vaccination with a Pasteurella (Mannheimia) haemolytica serotype A1 bacterin. Samples were also collected from 17 goats on days 21 and 35. Isolated Pasteurella spp were assigned to biovariant groups on the basis of results of biochemical utilization tests and serotyped. Serum antibody titers were determined.

Results—Multiple strains of Pasteurellaspp were isolated from swab specimens and assigned to 30 nonhemolytic and 14 β-hemolytic biovariant groups. The most common biovariant isolated was nonhemolytic P trehalosi belonging to group 2. This strain was isolated from 41 goats. Nonhemolytic P haemolytica strains were isolated from 31 goats, whereas β-hemolytic strains of P trehalosi and P haemolytica were isolated from 8 and 35 goats, respectively. Vaccination with the A1 serotype did not affect the proportion of goats from which we isolated each biovariant group or the number of biovariant groups isolated.

Conclusion and Clinical Relevance—Multiple strains of P haemolytica and P trehalosi belonging to nonhemolytic and β-hemolytic biovariant groups were isolated from the pharynx of healthy domestic pack goats. Because hemolytic activity correlates with leukotoxin production, β-hemolytic strains may have a greater potential to cause disease in naive populations of wild ruminants. However, vaccination with an A1 serotype bacterin did not decrease the proportion of culture-positive goats. (Am J Vet Res 2002;63:119–123)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare the effects of 2 preoperative anti-inflammatory regimens on intraocular inflammation following phacoemulsification.

Design—Randomized controlled trial

Animals—21 dogs with immature cataracts.

Procedures—All dogs had cataract surgery via phacoemulsification, and most received prosthetic intraocular lenses. Dogs were randomly divided into 2 groups. Group A dogs were treated topically with prednisolone acetate for 7 days prior to surgery, whereas prednisolone acetate treatment commenced the evening prior to surgery in group B dogs. Postoperative care was identical for both groups. Blood-aqueous barrier breakdown was quantified by use of anterior chamber fluorophotometry, with fluorescein entry into the anterior chamber measured 2 and 9 days after surgery compared with baseline scans obtained prior to surgery. Ophthalmic examinations were performed before surgery and 1 day, 9 days, 3 weeks, 7 weeks, 3 months, and 6 months after surgery. A subjective inflammation score was established at each examination. Intraocular pressures were measured 4 and 8 hours after surgery and at each follow-up examination.

Results—There was no difference in the extent of blood-aqueous barrier disruption between the groups at 2 or 9 days after surgery. Subjective inflammation scores were also similar at most time points. Dogs in group A developed postoperative ocular hypertension at a higher frequency (60%) than did those in group B (18%).

Conclusions and Clinical Relevance—In dogs that underwent cataract surgery via phacoemulsification, a full week of topical prednisolone acetate treatment prior to surgery did not decrease postoperative inflammation, compared with commencement of topical prednisolone acetate treatment the evening prior to surgery, and was associated with a greater incidence of postoperative ocular hypertension.

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

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.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To assess heritability and mode of inheritance for hypoadrenocorticism in Bearded Collies.

Animals—635 Bearded Collies.

Procedure—Dogs were classified as affected by hypoadrenocorticism or unaffected. Phenotypic and pedigree data were analyzed. Heritability was estimated by use of Bayesian statistical methods. Regressive logistic models for complex segregation analyses were used to characterize mode of inheritance.

Results—Hypoadrenocorticism was diagnosed in 60 (9.4%) dogs. Heritability of hypoadrenocorticism was estimated to be 0.76 with both sexes affected with equal probability. Evaluation of the pedigrees did not support a Mendelian autosomal dominant mode of inheritance. Evidence from the complex segregation analysis for a single locus of large effect on hypoadrenocorticism was not convincing.

Conclusions and Clinical Relevance—Hypoadrenocorticism in Bearded Collies is highly heritable. Although a precise genetic mechanism responsible for inheritance of the disorder remains undetermined, breeding decisions must include consideration of the genetic likelihood of passing on this deleterious disorder to offspring of affected dams and sires. (Am J Vet Res 2002;63:643–647).

Full access
in American Journal of Veterinary Research

Abstract

Objective—To characterize concurrent disorders in dogs with diabetes mellitus (DM).

Design—Retrospective study.

Animals—221 dogs with DM.

Procedure—Medical records were reviewed, and clinical signs, physical examination findings, and results of clinicopathologic testing, urinalysis, aerobic bacterial culture of urine samples, coagulation testing, endocrine testing, histologic evaluation, diagnostic imaging, and necropsy were recorded.

Results—For most dogs, CBC results were normal. Common serum biochemical abnormalities included hypochloremia (127 dogs, 60%) and high alanine aminotransferase (163, 78%), aspartate aminotransferase (78, 71%), and alkaline phosphatase (188, 90%) activities. Venous pH and serum ionized calcium concentration were measured in 121 and 87 dogs, respectively, and were low in 56 (46%) and 41 (47%) dogs. Lipemia was observed in 92 (42%) dogs. Urine samples from 159 (72%) dogs were submitted for aerobic bacterial culture, and 34 (21%) yielded bacterial growth. Escherichia coli was the most commonly isolated organism. Thirty-six (16%) dogs had dermatitis or otitis. Hyperadrenocorticism was diagnosed in 51 (23%) dogs on the basis of clinical signs and results of a low-dose dexamethasone suppression test (41 dogs), an adrenocorticotropic hormone stimulation test (5), both tests (4), or histologic evaluation of necropsy specimens (1). Acute pancreatitis was diagnosed in 28 (13%) dogs. Eleven (5%) dogs had tumors for which a histologic diagnosis was obtained. Eight (4%) dogs were hypothyroid.

Conclusions and Clinical Relevance—Results suggest that dogs with diabetes mellitus may have many concurrent disorders. The most commonly identified concurrent disorders included hyperadrenocorticism, urinary tract infection, dermatitis, otitis, acute pancreatitis, neoplasia, and hypothyroidism. (J Am Vet Med Assoc 2000;217:1166–1173)

Restricted access
in Journal of the American Veterinary Medical Association