Effects of intramuscular sedative and opioid combinations on tear production in dogs

The effect of commonly used sedation protocols on tear production rate was evaluated in dogs. Schirmer I tear tests were examined before and after intramuscular injection of acepromazine and oxymorphone (ACE + OXY; n  = 7), diazepam and butorphanol (DIA + BUT; n  = 8), and xylazine and butorphanol (XYL + BUT; n  = 8). Two Schirmer I tear tests were also performed 15–25 min apart in dogs which received no sedative drugs (control; n  = 4). Tear production rate decreased to 15 ± 2, 17 ± 1, and 6 ± 1 mm min⁻¹, respectively, while control animals averaged 21 ± 2 mm min⁻¹ at the same time point. Because XYL + BUT profoundly decreased tear production rate, we evaluated the two drugs separately. While BUT mildly decreased tear production when given alone to dogs (18 ± 1 mm min⁻¹; n  = 5), xylazine had no effect on tear production. Thus it appears that the two agents act synergistically to decrease tear production rate in dogs. Moreover, sterile ocular lubricant or tear replacement should be used during XYL + BUT sedation.     

Effects of medetomidine and medetomidine-butorphanol combination on Schirmer tear test 1 readings in dogs

Medetomidine is a commonly used sedative in veterinary medicine whether administered alone or in combination with an opioid such as butorphanol. There are no previous studies that look at the effects of this drug on sequential Schirmer tear test (STT) 1 readings in dogs, including effects on tear production after reversal of the drug. The present study looked at two groups of 10 dogs each that were sedated with intravenous medetomidine or a combination of medetomidine and butorphanol. All dogs had tear readings taken presedation, 15 min postsedation, and 15 min after reversal of medetomidine with atipamezole. Results revealed that intravenous sedation with medetomidine and medetomidine-butorphanol in dogs with no history of ophthalmic disease and presedation STT 1 readings above 15 mm/min, causes a significant decrease in tear production that is measurable at 15 min postsedation. Readings returned to near presedation values within 15 min postreversal in most cases. It is therefore recommended that all eyes be treated with a tear substitute from the time the sedative is given until at least 15 min after reversal.     

Trial of an inactivated vaccine against egg drop syndrome 76 in New Zealand

There is a legal requirement to provide analgesia for velvet antler removal in New Zealand. Currently, this is achieved using local anaesthetic blockade, with or without systemically administered sedative/analgesic agents, or by compression in 1-year-old stags. Lignocaine hydrochloride 2% is most commonly used and is most effective when administered as a high-dose ring block. Combinations of various amino-amide local anaesthetic agents can achieve rapid onset and prolonged duration of analgesia, though concerns about drug residues and carcinogenic potential of a lignocaine metabolite have led to consideration of the amino-ester family of local anaesthetics as alternatives.

Systemically administered analgesics, including opioids, α2-adrenergic agents and ketamine provide dose-dependent sedation and analgesia. However, none are sufficient, alone or in combination, to produce surgical analgesia at currently recommended dose rates and when reversal agents are given, analgesic effects are usually reversed as well as sedation. Thus, local anaesthetic blockade is still indicated, though the potential for drug or drug-metabolite residues in velvet antler remains a concern.

The need for and effectiveness of non-steroidal anti-inflammatory drugs (NSAIDs) for post-operative analgesia requires investigation. Amitriptyline, locally administered K-opioid agonists, tramadol and other systemically administered agents may warrant future investigation for surgical and post-operative analgesia for velvet antler removal.     

USE OF MEDETOMIDINE AS A PREANAESTHETIC IN BIRDS

Medetomidine, an α₂-adrenoceptor agonist, was used to balance ketamine anaesthesia in birds. Twenty zebra doves weighing 40 to 60 g were equally divided into 2 groups. Group 1 was used to evaluate the effects of 100 mg/kg of 5% ketamine and of 0.1 mg/kg of 0.005% medetomidine in combination with 100 mg/kg of 5% ketamine. Group 2 was used to study the effects of 200 mg/kg of 5% ketamine and of 30 mg/kg of 1% pentobarbital. All injections were made intramuscularly. Medetomidine-ketamine combination provided better analgesia, deeper anaesthesia, and smoother recovery with less wing flapping than with ketamine alone. The anaesthetic effect of the combination was comparable to that of pentobarbital but recovery was smoother. The selection of preanesthetic and anaesthetic medications is one of the problems associated with avian surgery. Medetomidine is a new sedative compound whose effect is mediated via the stimulation of the central α₂-adrenoceptors. It provides analgesic and sedative or anaesthetic effects in dogs and cats (Vähä, 1989) and sedative effect in zebra doves (Cherdchanpipat et al., 1989). This study was designed to evaluate the effect of medetomidine in combination with ketamine, the anaesthetic of choice for a number of avian species. The combination effect was compared with the effect of ketamine given alone, and with the effect of pentobarbital, the anaesthetic used successfully for decades by a number of practitioners.     

Analysis of tear uptake by the Schirmer tear test strip in the canine eye

OBJECTIVE: To analyze the uptake of tears in a Schirmer tear test (STT) in vitro and in vitro. MATERIALS AND METHODS: Uptake of fluid by Schirmer tear test strips was studied in vitro by examining fluid uptake over time from an unlimited fluid supply as well as with specific fluid volumes applied to the test strip. Uptake of fluid by Schirmer tear test strips was evaluated in a population of 100 ophthalmologically normal dogs together with a group of 40 dogs with tear film abnormalities such as keratoconjunctivitis sicca (KCS) or epiphora. Each animal was given a full ophthalmic examination followed by a standard Schirmer tear test extended over between 3 and 5 min with the STT reading recorded every 5 s and plotted over time. To determine the effect of ocular irritation by the test strip, uptake of tears by test strips was determined before and after topical anesthesia in 20 dogs. RESULTS: In vitro examination of fluid uptake by the STT strips showed an initial rapid uptake followed by a gradual reduction in rate of uptake. Temporal evaluation of STT in vivo showed a similar rapid initial uptake of tear fluid, followed in the majority of cases by a sudden change to a steady state uptake of fluid. The initial gradient was 29.3 +/- 16.9 mm/min followed by a steady state uptake of 5.2 +/- 2.3 mm/min in normal dogs and 1.9 +/- 1.3 mm/min in dogs with KCS. This corresponds to a steady state tear turnover of 7.8 +/- 3.4 microL/min in normal dogs and 2.8 +/- 1.9 microL/min in animals with KCS. Dogs with nasolacrimal blockage and resultant epiphora showed a high initial gradient but final gradients were not statistically different from those of normal dogs. Discussion and conclusions Temporal evaluation of tear uptake by the STT shows substantial differences in rate of tear uptake at different time-points during the period of the test. RESULTS: of this study suggest that the initial rapid rise in STT value represents uptake from the tear lake followed by a slower tear uptake of tears from steady state tear production. Temporal examination of the Schirmer tear test allows a more precise evaluation of tear production than the standard STT measuring tear uptake in 1 min, together with estimation of the contribution to the test strip tear uptake of tears from the residual tear lake volume and those from continual tear production.     

Tear production in canine neonates – evaluation using a modified Schirmer tear test

Purpose The ability of human newborns to produce tears has been a subject of controversy in the literature since the mid‐20th century, and there has been considerable debate as to whether they are able to produce tears. Recently, it was established that total tear secretion (reflex + basal) in full‐term infants is similar to those of adults whereas both reflex and basal tear production is reduced in premature babies. The objectives of this study were to assess whether newborn dogs have measurable aqueous tear production at the fourth week of life and to evaluate a modified Schirmer tear test (mSTT) as a useful method for measuring neonatal tear production in dogs. Methods Thirty four‐week‐old healthy puppies from six litters were evaluated. A control group was composed of 10 normal adult dogs. The mSTT strips were obtained by cutting a 5 mm‐wide strip in half (making two 2.5 mm‐wide strips). The mSTT1 was performed in puppies and adult dogs. Values were compared using t‐tests. Results In neonates, the average value for the mSTT1 was 13.6 ± 3.07 (range = 7–19 mm/min), which was significantly lower in neonates than in adult dogs (23.25 ± 3.5, range = 17–30 mm/min, P < 0.0001). Conclusions Canine neonates do produce tears by the fourth week of life, which can be successfully measured with the mSTT. This report established for the first time that canine neonates have significantly reduced total (reflex + basal) tear secretion compared to adults.     

Effect of topical 1% tropicamide on Schirmer tear test results in clinically normal horses

Objective  To observe the effect of topical 1% tropicamide on equine tear production as measured by Schirmer I tear test.
Materials and methods  Fourteen adult horses received one drop of 1% tropicamide ophthalmic solution in one eye and the opposite eye served as the control. The tear production in both eyes was tested at 1, 2, 4, 6, and 24 h after 1% tropicamide administration.
Results  Measurements made 1 h after treatment revealed a significant reduction in Schirmer tear test values in tropicamide treated eyes ( P  = 0.002). The observed decrease in tear production was maintained up to 4 h after treatment ( P  = 0.002). Although tropicamide-induced decrease in STT values was observed in the treated eyes, the contralateral eyes did not show significant changes in Schirmer tear test results.
Conclusion  Single dose of topical 1% tropicamide resulted in statistically significant reduction in Schirmer tear test values in clinically normal horses.     

Measurement of tear production in black‐tufted marmosets (Callithrix penicillata) using three different methods: modified Schirmer’s I,phenol red thread and standardized endodontic absorbent paper points

Objective: To report normal tear production of healthy adult black‐tufted marmosets and propose a novel alternative for the measurement of the aqueous portion of tear production in animals with small eyes. Animal studied: Black‐tufted marmosets (Callithrix penicillata). Procedures: Tear production of 19 animals was evaluated by the following methods: modified Schirmer’s I, phenol red thread and the novel use of standardized endodontic absorbent paper points. These methods and results were compared. Additionally, blink frequency and palpebral fissure length were measured. Results: Modified Schirmer’s test I, mean = ?0.46 ± 3.41 mm/min; Phenol red thread, mean = 13.27 ± 5.41 mm/15 s.; Standardized endodontic paper points, size 30, mean = 9.32 ± 3.09 mm/min; Mean palpebral fissure length = 7.83 ± 0.72 mm. Blink frequency, mean = 20.27 ± 5.92/5 min. Conclusions: Normal parameters for blink frequency, palpebral fissure length and tear production measurement are presented. The palpebral fissure of black‐tufted marmoset is very small and tear production is one of the lowest reported for all animal species. A novel and practical alternative for tear production measurement using standardized endodontic absorbent paper points is presented and is indicated for animals with small eyes.     

Sedative effects of romifidine in the dog

The sedative and physiological effects of intravenous romifidine at 0, 20, 40, 80 and 120 μg/kg were investigated in five clinically normal adult male beagle dogs in a blind study using a Latin square design. Following the injection of romifidine, the dogs became ataxic and stood with a wide-based stance, they exhibited signs of skeletal muscle relaxation and their heads were lowered. All the dogs became recumbent and there was a reduction in the heart and respiratory rates. Increasing the dose from 20 to 40 μg/kg, or higher, produced a significant reduction in heart rate. There was an increase in the sedation score following even low doses of romifidine, and although measures of sedation showed no differences among romifidine doses, subjectively, the higher doses produced a more consistent effect. Dogs given lower doses of romifidine regained a standing position more rapidly than following the higher doses, although this effect was not significantly different. A second blind study compared the sedative effects of intravenous romifidine, at 40 and 80 μg/kg, with mede-tomidine at 10 μg/kg in six adult beagles. The cardiopulmonary and sedative effects were not significantly different between all regimens, although medetomidine at 10 μg/kg appeared to be intermediate in effect between romifidine at 40 and 80 μ/kg. The sedative and physiological effects of romifidine in dogs appear to be similar to other α₂-adrenoceptor agonists. Intravenous administration provided sedation which might be clinically useful.     

Effect of acepromazine or xylazine on tear production as measured by Schirmer tear test in normal cats

Objective  To evaluate the effect of acepromazine or xylazine on Schirmer tear test 1 results in clinically normal cats.
Animals  Sixteen healthy cross-breed cats.
Procedure  The animals were randomly divided into two groups of eight cats each. The first group was sedated with acepromazine alone (0.2 mg/kg) and the second group received only xylazine (2 mg/kg). All cats had Schirmer tear test (STT) readings taken prior to sedation and at 15 and 25 min postsedation.
Results  Sedation with acepromazine or xylazine in cats with normal pre-sedation STT 1 values caused a statistically significant decrease in mean values of tear production in both groups. In acepromazine group the mean ± SEM STT at T₁₅ and T₂₅ were 4.31 ± 0.98 ( P  < 0.001) and 5.18 ± 1.07 ( P  = 0.002). The post-treatment mean ± SEM values in xylazine group were 2.18 ± 0.97 ( P  < 0.001) and 2.62 ± 1.17 ( P  = 0.001) at 15 and 25 min respectively. Comparison between T₁₅ and T₂₅ in acepromazine group ( P  = 0.49) and xylazine group ( P  = 0.56) revealed no significant differences.
Conclusion  These observations indicate that both acepromazine or xylazine significantly reduced tear production in clinically normal cats. In cats, clinicians should measure STT values prior to utilizing acepromazine or xylazine as sedatives in order to accurately assess the results. Moreover, sterile ocular lubricant or tear replacement should be used as a corneal protectant during sedation with these drugs.     

The effect of third eyelid gland removal on the ocular surface of dogs

To evaluate the effect of third eyelid removal on the ocular surface of dogs, we operated on five young Beagle dogs and observed changes to tear function using the following tests: phenol red thread test (PRT), Schirmer tear test (STT-1), modified Schirmer tear test (STT-2), pH and tear break-up time (BUT). There was a significant decrease (37%) in STT-2 within 2 weeks after the excision and this declined further to 60% at 1 year. The pH value increased after excision. Presurgical pH was 7.17 ± 0.20 (mean ± SD), which increased to 7.55 ± 0.24 in the 14–60 days following removal, and further increased to 7.77 ± 0.65 at 1 year. The PRT and STT-1 decreased by 26% within 3–7 months compared to pre-excision values, but by 1 year the values recovered to near normal. The BUT pre-excision value was 24.0 ± 8.1 s, which shortened to 13.5 ± 4.5 s after 5 months and continued to decrease further during the study. There were no overt visual signs of KCS during the observational period. However, microinjury of the keratoconjunctival epithelium was observed for all operated eyes when vital staining was used at 1 year post surgery. Surgical excision of the third eyelid in Beagle dogs influenced tear quality level and affected the stability of the tear layer, and at 1 year there was evidence of microinjury to the keratoconjunctival epithelium.     

Effect of short-term diphenhydramine administration on aqueous tear production in normal dogs

Objective To perform a randomized, placebo‐controlled, masked clinical trial using a cross‐over design to determine the effect of oral diphenhydramine on aqueous tear production in normal dogs. Animals studied Seventeen dogs with normal ophthalmic examinations. Procedures Baseline tear production was established for each dog by performing Schirmer tear test I (STT I). Dogs received 20‐day treatment courses of both oral diphenhydramine and placebo solutions with a 10‐day washout period between treatment periods. Each dog was randomly assigned to receive diphenhydramine or placebo at the outset of the study. Measurements of STT I values were measured at regular intervals during the study and were conducted at the same time of day throughout the study to control for diurnal variations in tear production. The significance of the impact of diphenhydramine treatment on the quantity of aqueous tear production, as determine by STT results over time, was evaluated using regression analysis with appropriate transformation. Results Statistical comparisons at each measurement time, including baseline measurements between control and treatment groups, revealed no significant differences. Mean STT I levels also did not differ significantly at any measurement time compared to baseline for treatment or control groups. Conclusions Short‐term administration of oral diphenhydramine does not result in a significant decrease in aqueous tear production in normal dogs.     

Chemical analgesia for velvet antler removal in deer

There is a legal requirement to provide analgesia for velvet antler removal in New Zealand. Currently, this is achieved using local anaesthetic blockade, with or without systemically administered sedative/analgesic agents, or by compression in 1-year-old stags. Lignocaine hydrochloride 2% is most commonly used and is most effective when administered as a high-dose ring block. Combinations of various amino-amide local anaesthetic agents can achieve rapid onset and prolonged duration of analgesia, though concerns about drug residues and carcinogenic potential of a lignocaine metabolite have led to consideration of the amino-ester family of local anaesthetics as alternatives. Systemically administered analgesics, including opioids, alpha-2-adrenergic agents and ketamine provide dose-dependent sedation and analgesia. However, none are sufficient, alone or in combination, to produce surgical analgesia at currently recommended dose rates and when reversal agents are given, analgesic effects are usually reversed as well as sedation. Thus, local anaesthetic blockade is still indicated, though the potential for drug or drug-metabolite residues in velvet antler remains a concern. The need for and effectiveness of non-steroidal anti-inflammatory drugs (NSAIDs) for post-operative analgesia requires investigation. Amitriptyline, locally administered opioid agonists, tramadol and other systemically administered agents may warrant future investigation for surgical and post-operative analgesia for velvet antler removal.     

Adverse reactions of α2-adrenoceptor agonists in cats reported in 2003–2013 in Finland

Objective

To describe suspected adverse drug reactions in cats associated with use of α₂-adrenoceptor agonists.

Reference values for Schirmer tear tests I and II in clinically normal pigs

Objective To determine reference values for Schirmer tear tests I and II in clinically normal pigs. Animal studied Twenty clinically normal Landrace pigs (10 males and females) without ocular abnormalities were used in this study. Procedures In all pigs, Schirmer tear tests (STT) I and II were performed by using a sterile Schirmer tear test standardized strip (Schirmer‐Tränentest^®, Germany) placed in the lower conjunctival fornix for 1 min. Results For each test (STT I and STT II), no differences were observed between the right and left eyes (P ≥ 0.5). The mean ± SD STT I value was 15.6 ± 3.7 mm/min (range, 10–22 mm/min), while the mean STT II value was 12.4 ± 3.8 mm/minute (range, 5–18 mm/min). The mean STT II value was significantly lower than the STT I level (P < 0.001). Animal gender did not have a significant effect on STT I and II values (P = 0.52). The mean ± SD STT I/II values of 10 juvenile pigs were significantly lower than the mean ± SD STT I/II values of 10 adult pigs (P < 0.001). Conclusions This study of 20 Landrace pigs provided valuable information on normal STT I/II in this species. Knowledge of normal STT reference values in pigs enables the clinician to evaluate corneal pathology and diagnose tear deficiency syndromes with greater accuracy.     

A systematic review of the effects of injectable sedative and anesthetic drugs and inhalant anesthetics on intraocular pressure in the dog

ObjectiveThe purpose of this systematic review was to summarize the results of studies that have determined the effect of injectable and inhalant drugs used in anesthesia on intraocular pressure (IOP) in dogs.Databases usedA comprehensive search of research literature was performed without language restriction. The search utilized the PubMed, CAB Abstracts and the University of Georgia’s Galileo electronic databases using a combination of free text terms ‘Ophthalmology’, ‘Intraocular Pressure’, ‘Anesthetic’, ‘Anesthesia’, ‘Canine’ or ‘Dog’. The time frame searched was from 1970 to October 2018. Any published research paper that dealt with sedatives or anesthetics administered systemically and the canine eye was evaluated.ConclusionsThe effects of many anesthetic drugs in dogs with ocular pathology are largely unknown. Many anesthetic drugs do not induce clinically relevant changes in IOP in dogs with normal eyes, although some studies demonstrated results with statistically significant changes. The dose, route of administration, experimental conditions, drug combinations, timing of measurements, measurement technology and setting or individual animal characteristics may all produce some heterogeneity in results from multiple studies.     

Correlation between corneal sensitivity and quantity of reflex tearing in cows,horses, goats,sheep, dogs,cats, rabbits,and guinea pigs

Objective Guinea pigs have a very low threshold of corneal sensitivity and at the same time nearly no reflex tearing compared to dogs, cats, and horses. The question arose whether there is a general correlation between corneal sensitivity and the quantity of reflex tearing. Animals studied Totally 160 animals of 8 different species (20 animals per species) were investigated. Procedures The corneal touch threshold (CTT) was measured with a Cochet–Bonnet esthesiometer. The palpebral fissure length (PFL) was measured with a calliper ruler. The Schirmer tear test (STT) was modified by adapting the width of the STT strip to the PFL of every species. For the STT II, 0.4% oxybuprocaine was applied. Results Corneal touch threshold: Cows (1.67 g/mm²), horses (1.23 g/mm²), sheep (1.13 g/mm²), goats (1.44 g/mm²), dogs (2.16 g/mm²), and cats (1.33 g/mm²) show similar CTT values. In contrast, rabbits (6.21 g/mm²) and guinea pigs (7.75 g/mm²) show a significantly lower CTT. Tear Production Difference STT I ? STT II: Rabbits have the greatest decline in tear production with 38.4%, followed by sheep (33.3%), dogs (31.1%), cats (24.7%), cows (23.7%), horses (18.0%), and goats (14.0%). Guinea pigs have no decline, but a slight increase of ?16.0%. Correlation CTT and STT II ? STT I Difference: Pearson’s correlation coefficient shows a small, but significant correlation. The coefficient of determination can only forecast a value with 7.1% certainty. Conclusions The high variance and low reproducibility of results suggest that the measuring devices are inappropriate to assess the evaluated parameters. Therefore, no assured correlation between the corneal sensitivity and the quantity of reflex tearing could be found.     

Impact of preanaesthetic echocardiography on the planned anaesthetic management of cats

ObjectiveTo assess the impact of preanaesthetic echocardiography on the subsequent intended anaesthetic management plan in cats with incidental clinical findings that may indicate cardiac disease.Study designClinical study involving cats undergoing echocardiography and subsequent anaesthesia.AnimalsA total of 40 client-owned cats.MethodsEchocardiography was performed in conscious cats and the information was used to plan anaesthesia or sedation. An information sheet including relevant history, temperament, body condition score, clinical examination findings, current medication and results of any relevant tests such as haematology, biochemistry or Doppler blood pressure measurement was sent to three specialist anaesthetists and virtual case management plans were designed for each cat in two steps: step 1) anaesthetists were unaware of echocardiography results; and step 2) anaesthetists were aware of echocardiography results. In the second step the anaesthetists documented any changes to their original management plan, as either ‘step-up’ or ‘step-down’.ResultsOf the 40 cats, 26 had murmurs, four had a gallop rhythm, four had both findings and six had other findings. Pathology of potential haemodynamic significance was found on echocardiography in 23 cats, 17 of which anaesthetists had correctly identified as having disease before echocardiography. A proportion of cats with murmurs were subsequently deemed to have no significant pathology after echocardiography. Echocardiography findings in these cases were: dynamic left ventricular outflow tract obstruction (DLVOTO) without hypertrophy; DLVOTO without hypertrophy + dynamic right ventricular outflow tract obstruction (DRVOTO); DRVOTO; valvular dysplasia; normal. In a median of 26/40 (range 16–38) of cases, the anaesthetic plan was changed after provision of further information; in 15/40 (8–20) cases, this was a ‘step-up’ in care and in eight/40 (6–23) it was a ‘step-down’ in care. In cases with atrial enlargement (left atrium to aortic ratio of >1.6) and deemed at risk of cardiac failure, alpha-2 agonist use changed considerably with availability of echocardiography findings.Conclusionand clinical relevance Where there are abnormal cardiac findings on clinical examination in cats, echocardiography is required to accurately assess anaesthetic risk . The availability of echocardiographic information positively influences anaesthetic management.     

Effect of lacrimal punctal occlusion on tear production and tear fluorescein dilution in normal dogs

OBJECTIVE: To evaluate effects of lacrimal punctal plugs positioned in either the upper, lower, or combination of upper and lower lacrimal canaliculi on plug retention and tolerance; tear production, as measured by the Schirmer tear test; and the dilution of fluorescein within the tear film in normal dogs. MATERIAL AND METHODS: Lacrimal punctal plugs were positioned in the lower, upper, or combination of lower and upper plugs in six laboratory-quality Beagles under topical anesthesia. Retention of plugs was evaluated daily from 8 to 23 days by visual inspection and slit-lamp biomicroscopy. Schirmer tear tests (STT 1 without topical anesthesia) were performed at 48-h intervals. Dilution of fluorescein was determined at 5- and 45-min post-fluorescein instillations once weekly. RESULTS: Lacrimal punctal plugs of 0.4 and 0.6 mm in diameter were retained for 14 (lower plugs: 100%) and 23 days (75%), and for the upper plugs at 8 days less often (75%), and were infrequently locally nonirritating. Combination of lower and upper plugs seemed to adversely affect retention of either plug. When loss of the plugs occurred, a next larger size plug was necessary suggesting some stretching of the lacrimal canaliculi occurred. Pre- and postplug placement STT results indicated no change with lower and combination lacrimal punctal plugs, but decreased levels following upper lacrimal punctal plugs. Tear fluorescein levels at 5 and 45 min in control eye (no punctum plugs) were 3.39% and 0.14%, respectively. With lower, upper, and the combination of lower and upper lacrimal puncta plugs, tear fluorescein levels at 45 min were higher than the controls (lower: 0.76%; upper: 0.45%, and combination 0.56%). CONCLUSION: Lacrimal punctal silicone plugs are retained for 8-23 days in the lower, upper, and combined lower and upper canaliculi at high rates. Effects on STT levels appear limited. Fluorescein within the tear film persists longer with all different positioned lacrimal punctum plugs than in the control eyes.     

Keratoconjunctival effects of diabetes mellitus in dogs

OBJECTIVES: To compare Schirmer tear test (STT) values, corneal sensitivity, tear film break up times (TFBUTs), and tear glucose concentrations in relation to conjunctival microflora, and conjunctival cytologic and histologic findings among diabetic cataractous, nondiabetic cataractous, and nondiabetic noncataractous dogs. Procedures Fifteen dogs in each category underwent neuro-ophthalmic examination; aerobic, anaerobic and fungal conjunctival cultures; assessment of corneal touch threshold (CTT), STT, tear glucose, TFBUT; and conjunctival cytology and histology (in certain cases only). Degree of cataract and uveitis were critically graded. Glycemic control was estimated using serum fructosamine and glycosylated hemoglobin. RESULTS: STT values were significantly lower in diabetic cataractous than nondiabetic noncataractous dogs. CTT of diabetic cataractous dogs was significantly lower than that of nondiabetic noncataractous dogs. Mean TFBUTs were significantly less in diabetic cataractous dogs than nondiabetic cataractous and nondiabetic noncataractous dogs. Tear glucose concentrations were significantly higher in diabetic cataractous dogs than nondiabetic cataractous and nondiabetic noncataractous dogs. Conjunctival microbial isolates did not differ among groups. There were no significant differences in degree of cataract or uveitis between diabetic cataractous and nondiabetic cataractous groups. There was mild submucosal inflammatory infiltrate in conjunctival specimens from diabetic dogs. Conjunctival epithelial dysplasia and/or squamous metaplasia was/were detected in conjunctival biopsies of 5/7 diabetic dogs. Reductions in conjunctival goblet cell (GC) densities were noted in 4/7 diabetic dogs; there were no significant differences in mean GC densities among the three groups. CONCLUSIONS: Diabetic cataractous dogs have significantly altered keratoconjunctival characteristics compared to nondiabetic cataractous and nondiabetic noncataractous dogs.