Effects of dexmedetomidine alone or in combination with opioids on intraocular pressure in healthy Beagle dogs.

OBJECTIVE: To evaluate the effects of dexmedetomidine alone or in combination with different opioids on intraocular pressure (IOP) in dogs. STUDY DESIGN: Experimental, prospective, crossover, randomized, blinded study. ANIMALS: A total of six Beagle dogs (two males and four females) aged 2 years and weighing 15.9 ± 2.9 kg (mean ± standard deviation). METHODS: Dogs were distributed randomly into seven treatments (n = 6 per treatment) and were administered dexmedetomidine alone (10 µg kg-1; Dex) or in combination with butorphanol (0.15 mg kg-1; DexBut), meperidine (5 mg kg-1; DexMep), methadone (0.5 mg kg-1; DexMet), morphine (0.5 mg kg-1; DexMor), nalbuphine (0.5 mg kg-1; DexNal) or tramadol (5 mg kg-1; DexTra). All drugs were administered intramuscularly. IOP was measured before drug injection (time 0, baseline) and every 15 minutes thereafter for 120 minutes (T15-T120). RESULTS: There were significant reductions in IOP compared with baseline in treatments Dex and DexMep at times T30-T120, and in treatment DexMet at T15-T90. IOP decreased compared with baseline in treatments DexBut, DexNal and DexTra at all evaluation times. No changes in IOP were seen in treatment DexMor. The mean IOP values in treatment DexMet at T105-T120 were higher than those for other treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Dexmedetomidine alone or in combination with butorphanol, meperidine, methadone, nalbuphine or tramadol resulted in decreased IOP for 120 minutes in dogs. The magnitude of the reduction was small and lacked clinical significance.

Effects of ketamine constant rate infusions on cardiac biomarkers and cardiac function in dogs.

OBJECTIVE: To evaluate the effects of ketamine continuous rate infusions (CRI) at two dose rates on cardiovascular function and serum creatine kinase MB isoenzyme (CK-MB) and troponin I in healthy conscious dogs. STUDY DESIGN: Experimental, prospective, crossover, randomized, blinded study. ANIMALS: Eight adult mixed-breed dogs, aged 6±1 years and weighing 19±8.6 kg (mean±standard deviation). METHODS: Dogs were administered an intravenous bolus of ketamine (0.5 mg kg-1) followed by a ketamine CRI for 12 hours (20 µg kg-1 minute-1; treatment TC20 or 40 µg kg-1 minute-1; treatment TC40). Sedation, heart rate (HR), mean arterial pressure (MAP), electrocardiographic and echocardiographic parameters were evaluated at baseline (T0) and 1 (T1), 2 (T2), 4 (T4), 8 (T8), 12 (T12) and 24 (T24) hours after ketamine infusion started. Serum concentrations of CK-MB and troponin I were measured at baseline and 12, 24 and 48 hours after infusion started. RESULTS: HR increased over the first 4 hours, significantly at T1 in TC20 and at T4 in TC40 when compared with T0 (p < 0.05). MAP was significantly increased at T2 in TC40 when compared with TC20. Behavioral changes, such as stereotypical head movements and twitches, occurred within 4 hours in TC40. There were no significant changes in echocardiographic examinations in any dog when compared with baseline. There were no temporal changes in serum CK-MB activity either within or between treatments (p > 0.05). No troponin I was detected in any sample. CONCLUSIONS AND CLINICAL RELEVANCE: No indication of myocardial injury resulting from ketamine infusion was detected in this study in healthy dogs. Further studies are needed to assess the ketamine infusion effects on antinociception and other organ function not evaluated in the present study.

Effects of dexmedetomidine combined with commonly administered opioids on clinical variables in dogs.

OBJECTIVE To evaluate cardiopulmonary, sedative, and antinociceptive effects of dexmedetomidine combined with commonly administered opioids in dogs. ANIMALS 8 healthy Beagles. PROCEDURES Dogs were sedated by IM administration of each of 7 treatments. Treatments comprised dexmedetomidine (0.01 mg/kg; Dex) and the same dose of dexmedetomidine plus butorphanol (0.15 mg/kg; Dex-But), meperidine (5 mg/kg; Dex-Mep), methadone (0.5 mg/kg; Dex-Meth), morphine (0.5 mg/kg; Dex-Mor), nalbuphine (0.5 mg/kg; Dex-Nal), or tramadol (5 mg/kg; Dex-Tram). Cardiorespiratory and arterial blood gas variables and sedative and antinociceptive scores were measured before drug injection (time 0; baseline) and at 15-minute intervals for 120 minutes. RESULTS Heart rate was reduced at all time points after injection of Dex-But, Dex-Mep, Dex-Meth, and Dex-Mor treatments. There was a significant reduction of mean arterial blood pressure for Dex-But, Dex-Mep, and Dex-Mor treatments at all time points, compared with baseline. There was a significant decrease in respiratory rate, compared with the baseline value, for Dex, Dex-But, Dex-Meth, and Dex-Tram treatments from 15 to 120 minutes. A significant decrease in arterial blood pH was detected from baseline to 120 minutes for all treatments, with differences among Dex, Dex-Mep, and Dex-Mor. Reduction in Pao2 was greater for the Dex-Mep treatment than for the other treatments. The highest sedation scores were detected for Dex-Mep and Dex-Meth treatments. Antinociceptive effects were superior for Dex-But, Dex-Meth, Dex-Mor, and Dex-Nal treatments. CONCLUSIONS AND CLINICAL RELEVANCE Drug combinations caused similar cardiorespiratory changes, with greater sedative effects for Dex-Mep and Dex-Meth and superior antinociceptive effects for Dex-But, Dex-Meth, Dex-Mor, and Dex-Nal.

Intraocular pressure and Schirmer tear test values in maned wolf (Chrysocyon brachyurus) / Pressão intraocular e teste lacrimal de Schirmer em lobos-guará (Chrysocyon brachyurus)

The purpose of this study was to establish baseline data on lacrimal quantity (STT-1) and intraocular pressure (IOP) in captive maned wolves. Ten healthy adult maned wolves were contained with a snare pole and muzzle and kept in decubitus of the left side. STT-1 measurement was performed on the lateral third of the lower conjunctival sac for one minute. The cornea was desensitized and intraocular pressure was measured with an tonopen. Average STT-1 in both eyes was 11±5mm.min-1, with no statistical difference between the left and right eye (p=0.960). Average IOP in both eyes was 20±6mmHg, with no statistical difference between the left and right eye (p=0.836). Average STT-1 was lower than, and IOP was the same as normal levels found in dogs. There was no statistical difference in the age of the animals, and STT-1 and IOP values. In the present paper, average maned wolf STT-1 levels were lower compared with those found in dogs, while the IOP was the same in maned wolves as in dogs. Due to the increased incidence in providing emergency care for maned wolf victims of road kill and fires, determination reference values of ocular parameters may improve the correct diagnosis and treatment of the disease.(AU)

O objetivo deste estudo foi estabelecer dados de referência sobre a produção lacrimal (STT-1) e pressão intraocular (PIO) em lobos-guará em cativeiro. Foram utilizados 10 lobos-guará, saudáveis e adultos. Os animais foram contidos com cambão e mordaça e mantidos em decúbito lateral esquerdo. O TLS foi realizado no terço médio da pálpebra inferior, durante um minuto. A córnea foi dessensibilizada e a PIO mensurada com tonopen. A média do TLS-1 dos olhos direitos e esquerdo foi 11±5mm/min, não havendo diferença significativa entre os olhos (p=0,960). A média da PIO dos olhos direitos e esquerdo foi 20±6mmHg, não observando diferença entre os olhos direitos e esquerdos (p=0,836). Média STT-1 foi menor do que, e PIO foi o mesmo que os níveis normais em cães. Não houve diferença estatística na idade dos animais e valores STT-1 e da PIO. No presente trabalho, os níveis médios de guará STT-1 foram mais baixos em comparação com as observadas nos cães, enquanto que a pressão intraocular foi a mesma nos lobos guará como em cães. Devido ao aumento da incidência na prestação de cuidados de emergência para vítimas de lobos-guará atropelamentos e incêndios, determinar os valores de referência dos parâmetros oculares podem melhorar o diagnóstico correto e tratamento de doenças.(AU)

Behavioral and cardiopulmonary effects of dexmedetomidine alone and in combination with butorphanol, methadone, morphine or tramadol in conscious sheep.

OBJECTIVE: To compare cardiopulmonary and sedative effects following administration of dexmedetomidine alone or with butorphanol, methadone, morphine or tramadol in healthy sheep. STUDY DESIGN: Randomized crossover study. ANIMALS: Six Santa Inês sheep, five females, one male, aged 12-28 months and weighing 40.1 ± 6.2 kg. METHODS: Sheep were assigned treatments of dexmedetomidine (0.005 mg kg(-1) ; D); D and butorphanol (0.15 mg kg(-1) ; DB); D and methadone (0.5 mg kg(-1) ; DM); D and morphine (0.5 mg kg(-1) ; DMO); or D and tramadol (5.0 mg kg(-1) ; DT). All drugs were administered intravenously with at least 7 days between each treatment. Rectal temperature, heart rate (HR), respiratory rate (fR ), invasive arterial pressure, blood gases and electrolytes were measured prior to administration of drugs (baseline, T0) and every 15 minutes following drug administration for 120 minutes (T15-T120). Sedation was scored by three observers blinded to treatment. RESULTS: HR decreased in all treatments and fR decreased in DM at T30 and DMO at T30 and T45. PaCO2 was increased in D, DB and DM compared with baseline, and PaO2 decreased in D at T15 and T45; in DB at T15 to T75; in DM at T15 to T60; in DMO at T15; and in DT at T15, T30 and T75. There was a decrease in temperature in D, DB and DM. An increased pH was measured in D at all time points and in DT at T30-T120. HCO3- and base excess were increased in all treatments compared with baseline. There were no statistical differences in sedation scores. CONCLUSIONS AND CLINICAL RELEVANCE: The combination of dexmedetomidine with butorphanol, methadone, morphine or tramadol resulted in similar changes in cardiopulmonary function and did not improve sedation when compared with dexmedetomidine alone.

Sedative and cardiopulmonary effects of xylazine alone or in combination with methadone, morphine or tramadol in sheep.

OBJECTIVE: To evaluate the cardiopulmonary and sedative effects of xylazine alone or in combination with methadone, morphine or tramadol in sheep. STUDY DESIGN: Experimental, prospective, crossover, randomized, blinded study. ANIMALS: Six Santa Inês breed sheep (females) aged 12 ± 8 months and weighing 39.5 ± 7.4 kg. METHODS: Sheep were sedated with each of four treatments in a randomized, crossover design, with a minimum washout period of 7 days between treatments. Treatments were: X [xylazine (0.1 mg kg(-1))]; XM [xylazine (0.1 mg kg(-1)) and methadone (0.5 mg kg(-1))]; XMO [xylazine (0.1 mg kg(-1)) and morphine (0.5 mg kg(-1))], and XT [xylazine (0.1 mg kg(-1)) and tramadol (5 mg kg(-1))]. Each drug combination was mixed in the syringe and injected intravenously. Sedation, heart rate (HR), mean arterial blood pressure (MAP), rectal temperature (RT°C), respiratory rate (fR), arterial blood gases and electrolytes were measured before drug administration (T0) and then at 15 minute intervals for 120 minutes (T15-T120). RESULTS: Heart rate significantly decreased in all treatments compared with T0. PaCO2 values in XM and XMO were higher at all time points compared with T0. In treatments X and XM, pH, bicarbonate (HCO3-) and base excess were increased at all time points compared with T0. PaO2 was significantly decreased at T15-T75 in XM, at all time points in XMO, and at T15 and T30 in XT. Sedation at T15 and T30 in XM and XMO was greater than in the other treatments. CONCLUSIONS AND CLINICAL RELEVANCE: The combinations of methadone, morphine or tramadol with xylazine resulted in cardiopulmonary changes similar to those induced by xylazine alone in sheep. The combinations provided better sedation, principally at 15 minutes and 30 minutes following administration.