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Abstract

OBJECTIVE To evaluate the pharmacokinetics of hydrocodone (delivered in combination with acetaminophen) and tramadol in dogs undergoing tibial plateau leveling osteotomy (TPLO).

ANIMALS 50 client-owned dogs.

PROCEDURES Dogs were randomly assigned to receive tramadol hydrochloride (5 to 7 mg/kg, PO, q 8 h; tramadol group) or hydrocodone bitartrate–acetaminophen (0.5 to 0.6 mg of hydrocodone/kg, PO, q 8 h; hydrocodone group) following TPLO with standard anesthetic and surgical protocols. Blood samples were collected for pharmacokinetic analysis of study drugs and their metabolites over an 8-hour period beginning after the second dose of the study medication.

RESULTS The terminal half-life, maximum serum concentration, and time to maximum serum concentration for tramadol following naïve pooled modeling were 1.56 hours, 155.6 ng/mL, and 3.90 hours, respectively. Serum concentrations of the tramadol metabolite O-desmethyltramadol (M1) were low. For hydrocodone, maximum serum concentration determined by naïve pooled modeling was 7.90 ng/mL, and time to maximum serum concentration was 3.47 hours. The terminal half-life for hydrocodone was 15.85 hours, but was likely influenced by delayed drug absorption in some dogs and may not have been a robust estimate. Serum concentrations of hydromorphone were low.

CONCLUSIONS AND CLINICAL RELEVANCE The pharmacokinetics of tramadol and metabolites were similar to those in previous studies. Serum tramadol concentrations varied widely, and concentrations of the active M1 metabolite were low. Metabolism of hydrocodone to hydromorphone in dogs was poor. Further study is warranted to assess variables that affect metabolism and efficacy of these drugs in dogs.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To determine the effect of topical ophthalmic administration of 0.005% latanoprost solution on aqueous humor flow rate (AHFR) and intraocular pressure (IOP) in ophthalmologically normal dogs.

ANIMALS

12 adult Beagles.

PROCEDURES

In a masked crossover design involving two 10-day experimental periods separated by a 7-day washout period, dogs were randomly assigned to first receive latanoprost or artificial tears (control) solution and then the opposite treatment in the later experimental period. Each experimental period was divided into a baseline phase (days 1 to 3), baseline fluorophotometry assessment (day 4), treatment phase (1 drop of latanoprost or artificial tears solution administered twice daily in each eye on days 5 to 9 and once on day 10), and posttreatment fluorophotometry assessment (day 10). Measured fluorescein concentrations were used to calculate baseline and posttreatment AHFRs. The IOP was measured 5 times/d in each eye during baseline and treatment (days 5 to 9) phases.

RESULTS

Mean baseline and posttreatment AHFR values did not differ significantly in either experimental period (latanoprost or control). In the latanoprost period, mean IOP was significantly lower during treatment than at baseline; there was no difference in corresponding IOP values during the control period. In the latanoprost period, mean IOP was significantly higher on the first day of treatment than on subsequent treatment days.

CONCLUSIONS AND CLINICAL RELEVANCE

In ophthalmologically normal dogs, topical ophthalmic administration of 0.005% latanoprost solution significantly decreased IOP but did not affect AHFR. Thus, the ocular hypotensive effect of latanoprost did not appear to have been caused by a reduction in aqueous humor production. (Am J Vet Res 2019;80:498–504)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To perform repeated anterior chamber fluorophotometry on both eyes of ophthalmologically normal dogs to measure fluorescein concentrations over a 5-day period and identify any change in the degree of anterior chamber fluorescence over time or difference between eyes.

Animals—9 healthy adult dogs (18 eyes).

Procedures—Each dog received an IV injection of 10% fluorescein solution, and anterior chamber fluorophotometry was performed 1 hour later on both eyes. This procedure was repeated at the same time each day for 5 consecutive days.

Results—A significant increase in fluorescein concentration was evident in the anterior chamber on day 5 in the right eye and days 2, 3, 4, and 5 in the left eye. There was no significant difference in concentration between the left and the right eyes on any day.

Conclusions and Clinical Relevance—The increase in ocular fluorescein concentration in the study dogs was unlikely to be of clinical importance and is only pertinent for subsequent research studies. This is a limitation that should be considered when reporting fluorophotometry data as fluorescein concentration or as change in fluorescein concentration from baseline.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To determine the effect of oral administration of robenacoxib on inhibition of anterior chamber paracentesis (ACP)-induced breakdown of the blood-aqueous barrier (BAB) and assess whether robenacoxib can cross an intact BAB in healthy cats.

ANIMALS 12 healthy adult domestic shorthair cats.

PROCEDURES Cats received robenacoxib (6-mg tablet in a treat, PO; n = 6) or a control treatment (treat without any drug, PO; 6) once daily for 3 days, beginning 1 day before ACP. One eye of each cat served as an untreated control, whereas the other underwent ACP, during which a 30-gauge needle was used to aspirate 100 μL of aqueous humor for determination of robenacoxib concentration. Both eyes of each cat underwent anterior chamber fluorophotometry at 0 (immediately before), 6, 24, and 48 hours after ACP. Fluorescein concentration and percentage fluorescein increase were used to assess extent of ACP-induced BAB breakdown and compared between cats that did and did not receive robenacoxib.

RESULTS Extent of BAB breakdown induced by ACP did not differ significantly between cats that did and did not receive robenacoxib. Low concentrations of robenacoxib were detected in the aqueous humor (mean, 5.32 ng/mL; range, 0.9 to 16 ng/mL) for 5 of the 6 cats that received the drug.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that oral administration of robenacoxib did not significantly decrease extent of BAB breakdown in healthy cats. Detection of low robenacoxib concentrations in the aqueous humor for most treated cats indicated that the drug can cross an intact BAB.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether addition of a continuous, local infusion of bupivacaine would improve postoperative analgesia in dogs undergoing total ear canal ablation.

Design—Randomized controlled trial.

Animals—16 dogs undergoing total ear canal ablation (12 unilaterally and 4 bilaterally with > 1 month between procedures).

Procedure—Dogs were randomly allocated to receive morphine (0.25 mg/kg [0.11 mg/lb]) at the end of the procedure (10 procedures) or morphine and a continuous, local infusion of bupivacaine (0.13 to 0.21 mg/kg/h [0.06 to 0.1 mg/lb/h]; 10 procedures). Dogs were observed for 48 hours after surgery. Additional doses of morphine were administered up to every 4 hours in dogs with signs of severe pain.

Results—Temperament, sedation, analgesia, and cumulative pain scores were not significantly different between groups any time after surgery. Recovery score was significantly higher for dogs that received bupivacaine than for control dogs 2 hours after extubation but not at any other time. Serum cortisol concentration was not significantly different between groups at any time but, in both groups, was significantly increased at the time of extubation, compared with all other observation times. Total number of additional doses of morphine administered was not significantly different between groups. Bupivacaine was not detected in the plasma of any of the dogs that received the local bupivacaine infusion.

Conclusions and Clinical Relevance—Results suggest that addition of a continuous, local infusion of bupivacaine did not significantly increase the degree of postoperative analgesia in dogs that underwent total ear canal ablation and were given morphine at the end of surgery. (J Am Vet Med Assoc 2005;227:414–419)

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To measure the effect of cold compress application on tissue temperature in healthy dogs.

Animals—10 healthy mixed-breed dogs.

Procedures—Dogs were sedated with hydromorphone (0.1 mg/kg, IV) and diazepam (0.25 mg/kg, IV). Three 24-gauge thermocouple needles were inserted to a depth of 0.5 (superficial), 1.0 (middle), and 1.5 (deep) cm into a shaved, lumbar, epaxial region to measure tissue temperature. Cold (–16.8°C) compresses were applied with gravity dependence for periods of 5, 10, and 20 minutes. Tissue temperature was recorded before compress application and at intervals for up to 80 minutes after application. Control data were collected while dogs received identical sedation but with no cold compress.

Results—Mean temperature associated with 5 minutes of application at the superficial depth was significantly decreased, compared with control temperatures. Application for 10 and 20 minutes significantly reduced the temperature at all depths, compared with controls and 5 minutes of application. Twenty minutes of application significantly decreased temperature at only the middle depth, compared with 10 minutes of application.

Conclusions and Clinical Relevance—With this method of cold treatment, increasing application time from 10 to 20 minutes caused a further significant temperature change at only the middle tissue depth; however, for maximal cooling, the minimum time of application should be 20 minutes. Possible changes in tissue temperature and adverse effects of application > 20 minutes require further evaluation.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To measure the effect of warm compress application on tissue temperature in healthy dogs.

Animals—10 healthy mixed-breed dogs.

Procedures—Dogs were sedated with hydromorphone (0.1 mg/kg, IV) and diazepam (0.25 mg/kg, IV). Three 24-gauge thermocouple needles were inserted to a depth of 0.5 cm (superficial), 1.0 cm (middle), and 1.5 cm (deep) into a shaved, lumbar, epaxial region to measure tissue temperature. Warm (47°C) compresses were applied with gravity dependence for periods of 5, 10, and 20 minutes. Tissue temperature was recorded before compress application and at intervals for up to 80 minutes after application. Control data were collected while dogs received identical sedation but with no warm compress.

Results—Mean temperature associated with 5 minutes of heat application at the superficial, middle, and deep depths was significantly increased, compared with the control temperature. Application for 10 minutes significantly increased the temperature at all depths, compared with 5 minutes of application. Mean temperature associated with 20 minutes of application was not different at the superficial or middle depths, compared with 10 minutes of application. Temperature at the deep depth associated with 10 minutes of application was significantly higher, compared with 20 minutes of application, but all temperature increases at this depth were minimal.

Conclusions and Clinical Relevance—Results suggested that application of a warm compress should be performed for 10 minutes. Changes in temperature at a tissue depth of 1.5 cm were minimal or not detected. The optimal compress temperature to achieve therapeutic benefits was not determined.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the accuracy of a real-time, continuous glucose monitoring system (CGMS) in healthy dogs undergoing anesthesia for elective ovariohysterectomy or orchiectomy.

Animals—10 healthy dogs undergoing routine elective surgery.

Procedures—A CGMS was placed and used to obtain calculated glucose measurements before, during, and after anesthesia in each dog. Periodically, CGMS measurements were compared with concurrent measurements of glucose concentration in peripheral venous blood obtained with a portable chemistry analyzer (PCA).

Results—CGMS-calculated glucose measurements were significantly different from PCA blood glucose measurements during most of the anesthetic period. The CGMS values differed from PCA values by > 20% in 54 of 126 (42.9%) paired measurements obtained during the anesthetic period. Hypoglycemia was evident in CGMS measurements 25 of 126 (19.8%) times during anesthesia. By comparison, only 1 incident of hypoglycemia was detected with the PCA during the same period.

Conclusions and Clinical Relevance—Use of the CGMS for routine monitoring of interstitial glucose concentration as an indicator of blood glucose concentration during anesthesia cannot be recommended. Additional investigation is necessary to elucidate the cause of discrepancy between CGMS results and PCA data during anesthesia.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To evaluate pharmacokinetics of cefazolin after IV injection of cefazolin (22 mg/kg) and after simultaneous IV and IM injections of cefazolin (total dose, 44 mg/kg) to dogs.

ANIMALS 12 adult Beagles.

PROCEDURES Dogs (6/group) were assigned to receive a single injection of cefazolin (IV group; 22 mg/kg, IV) or simultaneous injections (IV + IM group; 22 mg/kg, IV, and 22 mg/kg, IM). Interstitial fluid was collected over a 5-hour period by use of ultrafiltration probes for pharmacokinetic analysis.

RESULTS Mean cefazolin concentration in the interstitial fluid at 1, 1.5, 2, 3, 4, and 5 hours after injection was 39.6, 29.1, 21.2, 10.3, 6.4, and 2.7 μg/mL, respectively, for the IV group and 38.3, 53.3, 46.4, 31.7, 19.1, and 8.9 μg/mL, respectively, for the IV + IM group. Mean area under the concentration-time curve extrapolated to infinity, maximum concentration, half-life, and time to maximum concentration was 74.99 and 154.16 h·μg/mL, 37.3 and 51.5 μg/mL, 0.96 and 1.11 hours, and 1.28 and 1.65 hours, respectively, for the IV and IV + IM groups.

CONCLUSIONS AND CLINICAL RELEVANCE Cefazolin concentrations in interstitial fluid of dogs were maintained at > 4 μg/mL for 4 hours after a single IV injection and for 5 hours after simultaneous IV and IM injections. Therefore, simultaneous IV and IM administration of cefazolin 30 to 60 minutes before surgery should provide interstitial fluid concentrations effective against the most common commensal organisms (Staphylococcus spp and Streptococcus spp) on the skin of dogs for surgical procedures lasting ≤ 4 hours.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To evaluate effects of simultaneous intra-articular and IV injection of autologous adipose-derived stromal vascular fraction (SVF) and platelet-rich plasma (PRP) to dogs with osteoarthritis of the hip joints.

ANIMALS 22 client-owned dogs (12 placebo-treated [control] dogs and 10 treated dogs).

PROCEDURES Dogs with osteoarthritis of the hip joints that caused signs of lameness or discomfort were characterized on the basis of results of orthopedic examination, goniometry, lameness score, the Canine Brief Pain Inventory (CBPI), a visual analogue scale, and results obtained by use of a pressure-sensing walkway at week 0 (baseline). Dogs received a simultaneous intraarticular and IV injection of SVF and PRP or a placebo. Dogs were examined again 4, 8, 12, and 24 weeks after injection.

RESULTS CBPI scores were significantly lower for the treatment group at week 24, compared with scores for the control group. Mean visual analogue scale score for the treatment group was significantly higher at week 0 than at weeks 4, 8, or 24. Dogs with baseline peak vertical force (PVF) in the lowest 25th percentile were compared, and the treatment group had a significantly higher PVF than did the control group. After the SVF-PRP injection, fewer dogs in the treated group than in the control group had lameness confirmed during examination.

CONCLUSIONS AND CLINICAL RELEVANCE For dogs with osteoarthritis of the hip joints treated with SVF and PRP, improvements in CBPI and PVF were evident at some time points, compared with results for the control group.

Full access
in American Journal of Veterinary Research