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JEPM July 2015—Abstracts
ABSTRACTS
JEPM JULY 2015—ABSTRACTS ___________ Hyndman TH, Johnson RSP: Evidence for the vertical transmission of Sunshine virus. Vet Microbiol 175(2-4):179–184, 2015
Gruszynski K, Young A, Levine SJ, et al.: Streptococcus equi subsp. zooepidemicus infections associated with guinea pigs. Emerg Infect Dis 21(1):156–158, 2015
Sunshine virus is a paramyxovirus that is commonly associated with pythons. Infected pythons commonly develop neurologic and/or respiratory disease along with nonspecific clinical conditions (e.g., regurgitation and lethargy). The Sunshine virus has been found in carpet pythons (Morelia bredli and various subspecies of M. spilota) more than in any other snake species. Sunshine virus, which has been found in oral and cloacal swabs tested by polymerase chain reaction (PCR), is presumed to be transmitted horizontally, but heretofore, vertical transmission has been unproven. In 2013, Sunshine virus was found by PCR in a private Australian collection of more than 200 pythons, including an apparently healthy 3.5year-old female carpet python (M.s. variegata/M.s. mcdowelli hybrid). The dam was PCR positive for Sunshine virus on a combined oral-cloacal swab but was PCR negative on a blood sample tested 55 days before she laid her first ever clutch of eggs (N ¼ 21). The apparently healthy sire, with whom the dam had been in contact for over 2 months before oviposition, tested positive for Sunshine virus on blood and combined oral-cloacal swabs 57 days before oviposition. The clutch of eggs produced had no direct contact with any other clutch, and no eggs or hatchlings had further contact with the dam or sire. Within 34 to 113 days after oviposition, 3 eggs, each abnormal in appearance, were opened, and swabs were collected for Sunshine virus testing from the eggs’ surface, allantois, and amnion. Tissue samples were also collected from 2 of the eggs. All swabs of the allantois, amnion, and embryonic tissues were PCR positive for Sunshine virus. Combined oral-cloacal swabs from all hatchlings were PCR negative. Based on the lack of Sunshine virus detected on the eggs’ surface and in the incubator as well as the presence of Sunshine virus in both the parents, the presence of Sunshine virus in the eggs was attributed to vertical transmission.
Streptococcus zooepidemicus is a recognized, but rarely encountered, zoonotic pathogen that can infect horses, pigs, ruminants, monkeys, cats, dogs, and guinea pigs. This case report describes an adult man (patient 1) from Northern Virginia who presented to a hospital in February 2013 with flulike symptoms and worsening bilateral thigh pain. Physical examination revealed scleral icterus, rhabdomyolysis, and a skin rash involving both thighs. Soon after admission, the patient developed acute renal failure, sepsis, pneumonia, and edema in both legs. Blood culture revealed an infection attributed to group C streptococci, which was later identified as Streptococcus equi. After transfer to a tertiary care center, the patient underwent treatment for septic shock, mechanical ventilation for respiratory failure, and bilateral thigh fasciotomy and debridement to treat necrotizing fasciitis. After several months of treatment, the patient was discharged to a rehabilitation facility for an additional month. An elderly man (patient 2) related to patient 1 was admitted to the hospital 1 week after the hospitalization of patient 1. Clinical signs on admission were nausea, vomiting, chills, difficulty in breathing, weakness, abdominal and chest pain, and icterus. Within 2 days, patient 2 experienced respiratory failure, hypotension secondary to septic shock, and multiorgan failure. Group C Streptococcus spp. were isolated on culture and later identified as S. zooepidemicus. Patient 2 was discharged 18 days after hospitalization and received continuous oxygen therapy. Before falling ill, patient 1 had purchased 4 guinea pigs, 1 of which had died shortly after being acquired by the owner. Furthermore, patient 2 had cleaned the guinea pigs’ enclosure 2 days before he fell ill. The 3 remaining guinea pigs were surrendered to the Virginia Department of Agriculture and Consumer Service laboratory. Subsequently, S. zooepidemicus was isolated from 5 tissue samples (lymph node, conjunctival swabs, and nasal samples) collected from 2 of the 3 guinea pigs. The authors recommend that infection with S. zooepidemicus be
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Journal of Exotic Pet Medicine 24 (2015), pp 382–386
considered in the face of purulent wounds or systemic symptoms of infection in patients who have contact with guinea pigs or their environment. Zachariah TT, Mitchell MA, Watson MK, et al.: Effects of sevoflurane anesthesia on righting reflex and hemolymph gas analysis variables for Chilean rose tarantulas (Grammostola rosea). Am J Vet Res 75(6):521–526, 2014 This study’s objective was to assess the efficacy and safety of sevoflurane anesthesia for Chilean rose tarantulas (Grammostola rosea) and to determine changes in hemolymph concentrations of selected parameters between conscious and anesthetized spiders. A total of 12 apparently healthy subadult Chilean rose tarantulas of unknown sex were used in the study. Each was manually restrained for intracardiac collection of hemolymph before anesthesia was induced, and samples were submitted for analysis of pH, partial pressure of oxygen (PO2 ), partial pressure of carbon dioxide (PCO2 ), concentration of total carbon dioxide (TCO2 ), base excess, glucose, bicarbonate, sodium, potassium, chloride, and ionized magnesium and calcium. Spiders were placed in a custom-made 4-L anesthesia tank, which allowed manipulation of the animals in a closed chamber. Anesthesia was induced with 5% sevoflurane in oxygen delivered at 1 L/min by a standard anesthetic machine intended for use in small animals. Spiders were scored every 3 minutes for a normal, attempted, or absent righting reflex (RR). After induction of anesthesia (defined as the number of minutes until RR was absent for 2 consecutive evaluation intervals), the spiders were removed from the anesthesia chamber, and sevoflurane delivery was discontinued. A hemolymph sample was collected from each spider and submitted for evaluation of the parameters described earlier. The spiders were again placed in the chamber and exposed to 100% oxygen (delivered at 1 L/min) while being evaluated every 3 minutes for detection of an RR until they had recovered from anesthesia (defined as the number of minutes from the end of anesthetic induction until the RR was normal during 2 consecutive intervals). All spiders survived anesthesia with sevoflurane and hemolymph sample collection with no apparent adverse effects. The mean ⫾ standard deviation anesthetic induction and recovery times were 16 ⫾ 6 and 29 ⫾ 21 minutes, respectively. When compared with preinduction levels, postanesthesia concentrations of glucose, PO2 , and ionized magnesium were significantly higher, whereas the
base excess was significantly lower; however, these changes were not considered clinically important. Sevoflurane delivered at a concentration of 5% was judged to be adequate for clinical procedures but likely insufficient for procedures requiring complete immobilization of spiders. Guzman D S-M, KuKanich B, Drazenovich TL, et al.: Pharmacokinetics of hydromorphone hydrochloride after intravenous and intramuscular administration of a single dose to American kestrels (Falco sparverius). Am J Vet Res 75(6):527–531, 2014 Hydromorphone hydrochloride, a m-opioid receptor agonist, has a dose-responsive (0.1, 0.3, and 0.6 mg/kg) thermal antinociceptive effect after intramuscular (IM) administration in kestrels. This study was the first to determine pharmacokinetic parameters for hydromorphone hydrochloride in any avian species. A total of 12 healthy 2-year-old American kestrels (Falco sparverius) (6 females and 6 males) were assigned randomly to 3 groups of 4 birds each, with each group having predetermined times for blood collection. At the start of the study, each kestrel was manually restrained and received a hydromorphone hydrochloride dose of 0.6 mg/kg in the pectoral muscle. Blood was collected from the jugular vein or medial metatarsal vein at the following times after drug administration: 5 minutes, 1 hour, and 3 hours (n ¼ 4 kestrels); 0.25, 1.5, and 9 hours (n ¼ 4 kestrels); and 0.5, 2, and 6 hours (n ¼ 4 kestrels). A second experiment conducted 1 month later was identical in study design except that hydrochloride was administered intravenously (IV) in the right jugular vein. Plasma concentrations of hydromorphone were evaluated by using liquid chromatography with mass spectrometry. For determination of pharmacokinetic parameters, the mean plasma concentration was calculated for each blood sample collection time. Hydromorphone was detected in plasma samples collected from 2 and 3 birds at 6 hours after IM and IV administration, respectively, and was not detected in any plasma sample collected 9 hours after drug administration. After IM administration, 75% of the drug was absorbed. The maximum concentration (Cmax) of 112.1 ng/mL was reached at 0.08 hour (5 minutes), suggesting rapid absorption after IM administration. The terminal half-life (t1/2) was 1.25 and 1.26 hours after IV and IM administration, respectively. The authors concluded that hydromorphone should be used
Orcutt/Journal of Exotic Pet Medicine 24 (2015), pp 382–386
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with caution in American kestrels and other avian species until species-specific cardiorespiratory and thermoregulatory effects could be determined. Jones KL, Granger LA, Kearney MT, et al.: Evaluation of a ferret-specific formula for determining body surface area to improve chemotherapeutic dosing. Am J Vet Res 76(2):142–148, 2015 Estimates of body surface area (BSA) and dosage recommendations for ferrets are generally based on formulas and medical records generated for cats, which were initially derived from formulas used to calculate canine BSA. Typically, the formula is BSA ¼ K body weight2/3, where K is a constant denoting the shape of the species. The primary objective of this study was to use computed tomography (CT) to assess BSA in adult ferrets and to derive 2 ferret-specific BSA formulas: one based solely on body weight (BW) and the other using BW and another body measurement. Additionally, the study aimed to validate CT measurements of BSA by comparing CT-derived BSA measurements and the BSA both calculated by using formulas of basic geometric shapes and obtained by the traditional method of tape preparation of ferret carcasses. The investigators also aimed to determine if morphometric measurements differed between awake and anesthetized ferrets. A total of 19 healthy adult ferrets (12 males, with BW of 786 to 1850 g, and 7 females, with BW 620 to 1080 g), most of them client owned, were used in the study. For the tape method part of the protocol, 6 cadavers of adult ferrets (2 males and 4 females) were used. Ferrets were held vertically for measurement of ventral body length, dorsal body length with and without the tail, head circumference and diameter, and chest circumference. The animals were then anesthetized, and the same parameters were measured. Anesthetized ferrets were placed in sternal recumbency and CT was performed using 2.5-mm helical transverse images obtained from the nasal planum to the tail tip. A 3-dimensional CT surface image was then reconstructed for each ferret. The CT-derived calculations were validated by scanning 11 geometric shapes and manually calculating their surface areas. For the tape method, the body measurements listed earlier were recorded for each cadaver, and CT was performed. After each cadaver was fully shaved, the entire body was covered with medical tape. The tape “cast” was then cut away from each cadaver, and the 3-dimensional shape was cut into small pieces that 3 8 4
were laid on a sheet of paper. The outline of each piece of tape was scanned, and the pixels contained therein were counted by a computerized software program. A formula was then used to calculate the BSA from the total number of pixels. Most morphometric measurements varied significantly between awake and anesthetized ferrets. The BSA derived from CT measurements aligned closely with the surface area of the geometric shapes, thus validating the technique. There was also good agreement between the BSA derived from CT and from the tape method. Head diameter measured in awake ferrets was selected as the second measurement to be used with BW in calculating the BSA, and formulas were derived for use. However, when all formulas were compared, the traditional feline formula performed similarly to both the formula using only BW and the one adding in head diameter. The authors concluded that there was no practical reason to stop using the traditional feline formula for calculating BSA, and thus associated drug dosages, in ferrets. de Matos R, Ruby J, Van Hatten RA, et al.: Computed tomographic features of clinical and subclinical middle ear disease in domestic rabbits (Oryctolagus cuniculus): 88 cases (2007-2014). J Am Vet Med Assoc 246(3):336–343, 2015 The objective of this retrospective study was to compare computerized tomography (CT) abnormalities in the middle ear of domestic rabbits (Oryctolagus cuniculus) that showed clinical signs of middle ear disease with those in rabbits with subclinical disease and to determine the prevalence of otitis media in this species. Additionally, the frequency of association of predisposing factors was evaluated in rabbits with clinical and subclinical otitis media. A search of medical records for 784 rabbits evaluated at the Cornell University Hospital for Animals from June 2007 to February 2014 revealed 88 rabbits that had undergone CT of the head. These rabbits were divided into 2 subgroups: those examined because of clinical signs of otitis externa (head shaking; pinnal pruritus; foul-smelling ears; or, for rabbits with normally upright ears, holding the affected ear[s] down) or otitis media (e.g., vestibular signs or facial nerve paralysis) (group 1), and those examined for conditions not involving the ears (e.g., dental disease, upper respiratory tract disease, soft tissue or bony masses, and ocular or periocular disease) (group 2). All head CT scans had been performed in sedated or anesthetized rabbits.
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Follow-up visits or telephone or e-mail communications provided data on progression of subclinical otitis media. Of the 88 rabbits in which a head CT was obtained, 21 (24%) were in group 1 and 67 (76%) were in group 2. Rabbits in group 1 had signs of otitis externa (n ¼ 6), facial nerve paralysis (n ¼ 3), or vestibulitis (n ¼ 20). Of the rabbits in group 1, 12 (57%) had CT lesions of the middle ear. Of the 20 rabbits with vestibular disease, 11 (55%) had CT abnormalities consistent with otitis media, whereas the other 9 had no ear lesions and were presumptively diagnosed with central vestibular disease. All group 1 rabbits with CT signs of otitis media had attenuating material inside the tympanic bulla, while the incidence of bulla lysis and bulla thickening was 55% and 17%, respectively. Rabbits in group 2 had dental disease (n ¼ 33), upper respiratory tract disease (n ¼ 18), or other abnormalities involving the head or skull (n ¼ 16). Of the group 2 rabbits, 18 (27%) had CT lesions of the middle ear, all of which included increased attenuation in the bulla cavity, while bulla lysis and bulla thickening each had a prevalence of 19%. One of the group 2 rabbits was euthanized during CT because of advanced dental disease. Of the remaining 17 group 2 rabbits with CT lesions of otitis media, 5 rabbits developed signs of peripheral vestibular disease within 3 days to 2 years (median ¼ 10 months). Of the 30 rabbits in groups 1 and 2 having CT lesions consistent with otitis media, significantly more had lop ears (21/30, 70%). However, in contrast to findings of previous reports, there was no significant association between upper respiratory disease and CT lesions of the middle ear. Piazza S, Huynh M, Cauzinille L: Brainstem auditory-evoked response (BAER) in client-owner pet ferrets with normal hearing. Vet Rec 174(23):581–583, 2014 Brainstem auditory-evoked response (BAER) is an electrophysiologic method of determining hearing in human experimental studies using ferret models, and it is used in dogs and cats to assess congenital deafness. The objective of this study was to evaluate the clinical use of BAER testing in pet ferrets and to establish baseline data for normal hearing for future use in determining deafness. A total of 28 normal client-owned ferrets (18 females and 10 males ranging in age from 2 months to 2 years) were subjected to BAER testing performed with the same machine (Neuropack 2 MEB-7102, Nihon Kohden, Tokyo, Japan). Each ferret was anesthetized with isoflurane and positioned in
sternal recumbency. Electroencephalograph needles were placed subcutaneously, the positive electrode over the brainstem at the caudodorsal aspect of the skull, 2 negative electrodes at the ear base, and the ground electrode on the middorsum. A “click” stimulus was applied at an intensity of 90-dB sound pressure level through insert earphones held up to the opening of the ear canal, and sound waves were delivered at a rate of 20 Hz. The final BAER waveform represented an average of 500 sequential click responses. Total anesthesia time was approximately 10 minutes. The BAER recording had 4 reproducible waves; listed with their respective mean latencies at 90-dB sound pressure level, these were I (1.1 ms), II (1.9 ms), III (2.8 ms), and V (3.8 ms). The amplitude for wave I was 1.6 mV. BAER waveforms achieve their adult form when mammals reach 34 to 40 days of age. The authors concluded that the BAER technique described was a safe and routine protocol that could be performed in a clinical setting as a screening method for deafness in ferrets as young as 8 weeks of age. Minter LJ, Bailey KM, Harms CA, et al.: The efficacy of alfaxalone for immersion anesthesia in koi carp (Cyprinus carpio). Vet Anaesth Analg 41(4):398–405, 2014 Alfaxalone is a synthetic, neuroactive, steroid anesthetic that has been reported to be effective in fish and amphibians when delivered by a water bath. The goal of this study was to evaluate the efficacy and safety of a single induction dose and 2 maintenance doses of alfaxalone delivered by water immersion in koi carp (Cyprinus carpio) by assessing dose-related changes in behavior, serial blood gas parameters, and blood lactate concentrations. A total of 6 healthy adult koi, weighing 292 to 405 g, were used in the study. In this complete crossover study, each fish was exposed to a single induction dose of 10 mg/L followed by a maintenance dose of 1 or 2.5 mg/L. A 3-week washout period separated the anesthetic exposures so that each fish was eventually evaluated at maintenance doses of 1 mg/L and 2.5 mg/L. Before inducing anesthesia, after induction, and after the maintenance anesthetic period, blood was collected from each fish for measurement of CO2, O2, partial pressure of CO2 (pCO2), partial pressure of O2 (pO2), pH, bicarbonate concentration (HCO3), and lactate concentration. Fish were placed in a bucket with 8 L of water containing 10 mg/L of alfaxalone. After induction (i.e., when the fish were
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immobilized and exhibited loss of equilibrium), they were transferred to a recirculating fish anesthesia system using water containing either 1 or 2.5 mg/L of alfaxalone for anesthesia maintenance. The system washed the anesthetic through the mouth and across the gills at a flow rate of 2 L/min for a period of 20 minutes. During this time, the opercular rate and heart rate (detected by Doppler flow monitoring) were recorded every 5 minutes. Depth of anesthesia was assessed by needle insertion during blood collection and at the 10-minute interval by needle insertion into the epaxial musculature. After the anesthetic period, the fish were placed in 10 L of water for recovery. Neither the water pH nor the temperature was affected by the addition of alfaxalone. The anesthesia induction period lasted a median 6.3 minutes and 5.2 minutes for the 1 mg/L and 2.5 mg/L maintenance trials, respectively. At the 20-minute point after induction, opercular movement was significantly less for fish exposed to 2.5 mg/L, but heart rates did not differ between the 2 maintenance doses. Opercular movement decreased significantly by the end of the induction period and stopped completely for 45 minutes in 4 of the 6 fish maintained on 2.5 mg of alfaxalone/L. However, all fish recovered after exposure to anesthesia-free
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water. Recovery times were significantly longer for the 2.5 mg/L trial than for the 1 mg/L trial (median ¼ 26.4 and 11.8 minutes, respectively). Response to noxious stimuli was 4/6 and 0/6 with the 1 and 2.5 mg/L maintenance doses, respectively. When compared with preanesthesia levels, blood pH was significantly decreased and blood bicarbonate and lactate levels were significantly increased during and after anesthesia with alfaxalone; however, values did not differ significantly between maintenance doses. The authors concluded that 10 mg of alfaxalone/L delivered by water immersion provided rapid and reliable induction in koi. Anesthesia resulting from a dose of 1 mg of alfaxalone/L may be sufficient only for venipuncture, sample collection, or diagnostic imaging, whereas a dose of 2.5 mg/L may be more appropriate for surgical procedures.
CONNIE ORCUTT, DVM, Dip. ABVP (Avian; Exotic Companion Mammals) Brookline, MA USA r 2015 Published by Elsevier Inc. 1557-5063/15/2101-$30.00 http://dx.doi.org/10.1053/j.jepm.2015.06.003
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JEPM JULY 2015—ABSTRACTS ___________ Hyndman TH, Johnson RSP: Evidence for the vertical transmission of Sunshine virus. Vet Microbiol 175(2-4):179–184, 2015
Gruszynski K, Young A, Levine SJ, et al.: Streptococcus equi subsp. zooepidemicus infections associated with guinea pigs. Emerg Infect Dis 21(1):156–158, 2015
Sunshine virus is a paramyxovirus that is commonly associated with pythons. Infected pythons commonly develop neurologic and/or respiratory disease along with nonspecific clinical conditions (e.g., regurgitation and lethargy). The Sunshine virus has been found in carpet pythons (Morelia bredli and various subspecies of M. spilota) more than in any other snake species. Sunshine virus, which has been found in oral and cloacal swabs tested by polymerase chain reaction (PCR), is presumed to be transmitted horizontally, but heretofore, vertical transmission has been unproven. In 2013, Sunshine virus was found by PCR in a private Australian collection of more than 200 pythons, including an apparently healthy 3.5year-old female carpet python (M.s. variegata/M.s. mcdowelli hybrid). The dam was PCR positive for Sunshine virus on a combined oral-cloacal swab but was PCR negative on a blood sample tested 55 days before she laid her first ever clutch of eggs (N ¼ 21). The apparently healthy sire, with whom the dam had been in contact for over 2 months before oviposition, tested positive for Sunshine virus on blood and combined oral-cloacal swabs 57 days before oviposition. The clutch of eggs produced had no direct contact with any other clutch, and no eggs or hatchlings had further contact with the dam or sire. Within 34 to 113 days after oviposition, 3 eggs, each abnormal in appearance, were opened, and swabs were collected for Sunshine virus testing from the eggs’ surface, allantois, and amnion. Tissue samples were also collected from 2 of the eggs. All swabs of the allantois, amnion, and embryonic tissues were PCR positive for Sunshine virus. Combined oral-cloacal swabs from all hatchlings were PCR negative. Based on the lack of Sunshine virus detected on the eggs’ surface and in the incubator as well as the presence of Sunshine virus in both the parents, the presence of Sunshine virus in the eggs was attributed to vertical transmission.
Streptococcus zooepidemicus is a recognized, but rarely encountered, zoonotic pathogen that can infect horses, pigs, ruminants, monkeys, cats, dogs, and guinea pigs. This case report describes an adult man (patient 1) from Northern Virginia who presented to a hospital in February 2013 with flulike symptoms and worsening bilateral thigh pain. Physical examination revealed scleral icterus, rhabdomyolysis, and a skin rash involving both thighs. Soon after admission, the patient developed acute renal failure, sepsis, pneumonia, and edema in both legs. Blood culture revealed an infection attributed to group C streptococci, which was later identified as Streptococcus equi. After transfer to a tertiary care center, the patient underwent treatment for septic shock, mechanical ventilation for respiratory failure, and bilateral thigh fasciotomy and debridement to treat necrotizing fasciitis. After several months of treatment, the patient was discharged to a rehabilitation facility for an additional month. An elderly man (patient 2) related to patient 1 was admitted to the hospital 1 week after the hospitalization of patient 1. Clinical signs on admission were nausea, vomiting, chills, difficulty in breathing, weakness, abdominal and chest pain, and icterus. Within 2 days, patient 2 experienced respiratory failure, hypotension secondary to septic shock, and multiorgan failure. Group C Streptococcus spp. were isolated on culture and later identified as S. zooepidemicus. Patient 2 was discharged 18 days after hospitalization and received continuous oxygen therapy. Before falling ill, patient 1 had purchased 4 guinea pigs, 1 of which had died shortly after being acquired by the owner. Furthermore, patient 2 had cleaned the guinea pigs’ enclosure 2 days before he fell ill. The 3 remaining guinea pigs were surrendered to the Virginia Department of Agriculture and Consumer Service laboratory. Subsequently, S. zooepidemicus was isolated from 5 tissue samples (lymph node, conjunctival swabs, and nasal samples) collected from 2 of the 3 guinea pigs. The authors recommend that infection with S. zooepidemicus be
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Journal of Exotic Pet Medicine 24 (2015), pp 382–386
considered in the face of purulent wounds or systemic symptoms of infection in patients who have contact with guinea pigs or their environment. Zachariah TT, Mitchell MA, Watson MK, et al.: Effects of sevoflurane anesthesia on righting reflex and hemolymph gas analysis variables for Chilean rose tarantulas (Grammostola rosea). Am J Vet Res 75(6):521–526, 2014 This study’s objective was to assess the efficacy and safety of sevoflurane anesthesia for Chilean rose tarantulas (Grammostola rosea) and to determine changes in hemolymph concentrations of selected parameters between conscious and anesthetized spiders. A total of 12 apparently healthy subadult Chilean rose tarantulas of unknown sex were used in the study. Each was manually restrained for intracardiac collection of hemolymph before anesthesia was induced, and samples were submitted for analysis of pH, partial pressure of oxygen (PO2 ), partial pressure of carbon dioxide (PCO2 ), concentration of total carbon dioxide (TCO2 ), base excess, glucose, bicarbonate, sodium, potassium, chloride, and ionized magnesium and calcium. Spiders were placed in a custom-made 4-L anesthesia tank, which allowed manipulation of the animals in a closed chamber. Anesthesia was induced with 5% sevoflurane in oxygen delivered at 1 L/min by a standard anesthetic machine intended for use in small animals. Spiders were scored every 3 minutes for a normal, attempted, or absent righting reflex (RR). After induction of anesthesia (defined as the number of minutes until RR was absent for 2 consecutive evaluation intervals), the spiders were removed from the anesthesia chamber, and sevoflurane delivery was discontinued. A hemolymph sample was collected from each spider and submitted for evaluation of the parameters described earlier. The spiders were again placed in the chamber and exposed to 100% oxygen (delivered at 1 L/min) while being evaluated every 3 minutes for detection of an RR until they had recovered from anesthesia (defined as the number of minutes from the end of anesthetic induction until the RR was normal during 2 consecutive intervals). All spiders survived anesthesia with sevoflurane and hemolymph sample collection with no apparent adverse effects. The mean ⫾ standard deviation anesthetic induction and recovery times were 16 ⫾ 6 and 29 ⫾ 21 minutes, respectively. When compared with preinduction levels, postanesthesia concentrations of glucose, PO2 , and ionized magnesium were significantly higher, whereas the
base excess was significantly lower; however, these changes were not considered clinically important. Sevoflurane delivered at a concentration of 5% was judged to be adequate for clinical procedures but likely insufficient for procedures requiring complete immobilization of spiders. Guzman D S-M, KuKanich B, Drazenovich TL, et al.: Pharmacokinetics of hydromorphone hydrochloride after intravenous and intramuscular administration of a single dose to American kestrels (Falco sparverius). Am J Vet Res 75(6):527–531, 2014 Hydromorphone hydrochloride, a m-opioid receptor agonist, has a dose-responsive (0.1, 0.3, and 0.6 mg/kg) thermal antinociceptive effect after intramuscular (IM) administration in kestrels. This study was the first to determine pharmacokinetic parameters for hydromorphone hydrochloride in any avian species. A total of 12 healthy 2-year-old American kestrels (Falco sparverius) (6 females and 6 males) were assigned randomly to 3 groups of 4 birds each, with each group having predetermined times for blood collection. At the start of the study, each kestrel was manually restrained and received a hydromorphone hydrochloride dose of 0.6 mg/kg in the pectoral muscle. Blood was collected from the jugular vein or medial metatarsal vein at the following times after drug administration: 5 minutes, 1 hour, and 3 hours (n ¼ 4 kestrels); 0.25, 1.5, and 9 hours (n ¼ 4 kestrels); and 0.5, 2, and 6 hours (n ¼ 4 kestrels). A second experiment conducted 1 month later was identical in study design except that hydrochloride was administered intravenously (IV) in the right jugular vein. Plasma concentrations of hydromorphone were evaluated by using liquid chromatography with mass spectrometry. For determination of pharmacokinetic parameters, the mean plasma concentration was calculated for each blood sample collection time. Hydromorphone was detected in plasma samples collected from 2 and 3 birds at 6 hours after IM and IV administration, respectively, and was not detected in any plasma sample collected 9 hours after drug administration. After IM administration, 75% of the drug was absorbed. The maximum concentration (Cmax) of 112.1 ng/mL was reached at 0.08 hour (5 minutes), suggesting rapid absorption after IM administration. The terminal half-life (t1/2) was 1.25 and 1.26 hours after IV and IM administration, respectively. The authors concluded that hydromorphone should be used
Orcutt/Journal of Exotic Pet Medicine 24 (2015), pp 382–386
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with caution in American kestrels and other avian species until species-specific cardiorespiratory and thermoregulatory effects could be determined. Jones KL, Granger LA, Kearney MT, et al.: Evaluation of a ferret-specific formula for determining body surface area to improve chemotherapeutic dosing. Am J Vet Res 76(2):142–148, 2015 Estimates of body surface area (BSA) and dosage recommendations for ferrets are generally based on formulas and medical records generated for cats, which were initially derived from formulas used to calculate canine BSA. Typically, the formula is BSA ¼ K body weight2/3, where K is a constant denoting the shape of the species. The primary objective of this study was to use computed tomography (CT) to assess BSA in adult ferrets and to derive 2 ferret-specific BSA formulas: one based solely on body weight (BW) and the other using BW and another body measurement. Additionally, the study aimed to validate CT measurements of BSA by comparing CT-derived BSA measurements and the BSA both calculated by using formulas of basic geometric shapes and obtained by the traditional method of tape preparation of ferret carcasses. The investigators also aimed to determine if morphometric measurements differed between awake and anesthetized ferrets. A total of 19 healthy adult ferrets (12 males, with BW of 786 to 1850 g, and 7 females, with BW 620 to 1080 g), most of them client owned, were used in the study. For the tape method part of the protocol, 6 cadavers of adult ferrets (2 males and 4 females) were used. Ferrets were held vertically for measurement of ventral body length, dorsal body length with and without the tail, head circumference and diameter, and chest circumference. The animals were then anesthetized, and the same parameters were measured. Anesthetized ferrets were placed in sternal recumbency and CT was performed using 2.5-mm helical transverse images obtained from the nasal planum to the tail tip. A 3-dimensional CT surface image was then reconstructed for each ferret. The CT-derived calculations were validated by scanning 11 geometric shapes and manually calculating their surface areas. For the tape method, the body measurements listed earlier were recorded for each cadaver, and CT was performed. After each cadaver was fully shaved, the entire body was covered with medical tape. The tape “cast” was then cut away from each cadaver, and the 3-dimensional shape was cut into small pieces that 3 8 4
were laid on a sheet of paper. The outline of each piece of tape was scanned, and the pixels contained therein were counted by a computerized software program. A formula was then used to calculate the BSA from the total number of pixels. Most morphometric measurements varied significantly between awake and anesthetized ferrets. The BSA derived from CT measurements aligned closely with the surface area of the geometric shapes, thus validating the technique. There was also good agreement between the BSA derived from CT and from the tape method. Head diameter measured in awake ferrets was selected as the second measurement to be used with BW in calculating the BSA, and formulas were derived for use. However, when all formulas were compared, the traditional feline formula performed similarly to both the formula using only BW and the one adding in head diameter. The authors concluded that there was no practical reason to stop using the traditional feline formula for calculating BSA, and thus associated drug dosages, in ferrets. de Matos R, Ruby J, Van Hatten RA, et al.: Computed tomographic features of clinical and subclinical middle ear disease in domestic rabbits (Oryctolagus cuniculus): 88 cases (2007-2014). J Am Vet Med Assoc 246(3):336–343, 2015 The objective of this retrospective study was to compare computerized tomography (CT) abnormalities in the middle ear of domestic rabbits (Oryctolagus cuniculus) that showed clinical signs of middle ear disease with those in rabbits with subclinical disease and to determine the prevalence of otitis media in this species. Additionally, the frequency of association of predisposing factors was evaluated in rabbits with clinical and subclinical otitis media. A search of medical records for 784 rabbits evaluated at the Cornell University Hospital for Animals from June 2007 to February 2014 revealed 88 rabbits that had undergone CT of the head. These rabbits were divided into 2 subgroups: those examined because of clinical signs of otitis externa (head shaking; pinnal pruritus; foul-smelling ears; or, for rabbits with normally upright ears, holding the affected ear[s] down) or otitis media (e.g., vestibular signs or facial nerve paralysis) (group 1), and those examined for conditions not involving the ears (e.g., dental disease, upper respiratory tract disease, soft tissue or bony masses, and ocular or periocular disease) (group 2). All head CT scans had been performed in sedated or anesthetized rabbits.
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Follow-up visits or telephone or e-mail communications provided data on progression of subclinical otitis media. Of the 88 rabbits in which a head CT was obtained, 21 (24%) were in group 1 and 67 (76%) were in group 2. Rabbits in group 1 had signs of otitis externa (n ¼ 6), facial nerve paralysis (n ¼ 3), or vestibulitis (n ¼ 20). Of the rabbits in group 1, 12 (57%) had CT lesions of the middle ear. Of the 20 rabbits with vestibular disease, 11 (55%) had CT abnormalities consistent with otitis media, whereas the other 9 had no ear lesions and were presumptively diagnosed with central vestibular disease. All group 1 rabbits with CT signs of otitis media had attenuating material inside the tympanic bulla, while the incidence of bulla lysis and bulla thickening was 55% and 17%, respectively. Rabbits in group 2 had dental disease (n ¼ 33), upper respiratory tract disease (n ¼ 18), or other abnormalities involving the head or skull (n ¼ 16). Of the group 2 rabbits, 18 (27%) had CT lesions of the middle ear, all of which included increased attenuation in the bulla cavity, while bulla lysis and bulla thickening each had a prevalence of 19%. One of the group 2 rabbits was euthanized during CT because of advanced dental disease. Of the remaining 17 group 2 rabbits with CT lesions of otitis media, 5 rabbits developed signs of peripheral vestibular disease within 3 days to 2 years (median ¼ 10 months). Of the 30 rabbits in groups 1 and 2 having CT lesions consistent with otitis media, significantly more had lop ears (21/30, 70%). However, in contrast to findings of previous reports, there was no significant association between upper respiratory disease and CT lesions of the middle ear. Piazza S, Huynh M, Cauzinille L: Brainstem auditory-evoked response (BAER) in client-owner pet ferrets with normal hearing. Vet Rec 174(23):581–583, 2014 Brainstem auditory-evoked response (BAER) is an electrophysiologic method of determining hearing in human experimental studies using ferret models, and it is used in dogs and cats to assess congenital deafness. The objective of this study was to evaluate the clinical use of BAER testing in pet ferrets and to establish baseline data for normal hearing for future use in determining deafness. A total of 28 normal client-owned ferrets (18 females and 10 males ranging in age from 2 months to 2 years) were subjected to BAER testing performed with the same machine (Neuropack 2 MEB-7102, Nihon Kohden, Tokyo, Japan). Each ferret was anesthetized with isoflurane and positioned in
sternal recumbency. Electroencephalograph needles were placed subcutaneously, the positive electrode over the brainstem at the caudodorsal aspect of the skull, 2 negative electrodes at the ear base, and the ground electrode on the middorsum. A “click” stimulus was applied at an intensity of 90-dB sound pressure level through insert earphones held up to the opening of the ear canal, and sound waves were delivered at a rate of 20 Hz. The final BAER waveform represented an average of 500 sequential click responses. Total anesthesia time was approximately 10 minutes. The BAER recording had 4 reproducible waves; listed with their respective mean latencies at 90-dB sound pressure level, these were I (1.1 ms), II (1.9 ms), III (2.8 ms), and V (3.8 ms). The amplitude for wave I was 1.6 mV. BAER waveforms achieve their adult form when mammals reach 34 to 40 days of age. The authors concluded that the BAER technique described was a safe and routine protocol that could be performed in a clinical setting as a screening method for deafness in ferrets as young as 8 weeks of age. Minter LJ, Bailey KM, Harms CA, et al.: The efficacy of alfaxalone for immersion anesthesia in koi carp (Cyprinus carpio). Vet Anaesth Analg 41(4):398–405, 2014 Alfaxalone is a synthetic, neuroactive, steroid anesthetic that has been reported to be effective in fish and amphibians when delivered by a water bath. The goal of this study was to evaluate the efficacy and safety of a single induction dose and 2 maintenance doses of alfaxalone delivered by water immersion in koi carp (Cyprinus carpio) by assessing dose-related changes in behavior, serial blood gas parameters, and blood lactate concentrations. A total of 6 healthy adult koi, weighing 292 to 405 g, were used in the study. In this complete crossover study, each fish was exposed to a single induction dose of 10 mg/L followed by a maintenance dose of 1 or 2.5 mg/L. A 3-week washout period separated the anesthetic exposures so that each fish was eventually evaluated at maintenance doses of 1 mg/L and 2.5 mg/L. Before inducing anesthesia, after induction, and after the maintenance anesthetic period, blood was collected from each fish for measurement of CO2, O2, partial pressure of CO2 (pCO2), partial pressure of O2 (pO2), pH, bicarbonate concentration (HCO3), and lactate concentration. Fish were placed in a bucket with 8 L of water containing 10 mg/L of alfaxalone. After induction (i.e., when the fish were
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immobilized and exhibited loss of equilibrium), they were transferred to a recirculating fish anesthesia system using water containing either 1 or 2.5 mg/L of alfaxalone for anesthesia maintenance. The system washed the anesthetic through the mouth and across the gills at a flow rate of 2 L/min for a period of 20 minutes. During this time, the opercular rate and heart rate (detected by Doppler flow monitoring) were recorded every 5 minutes. Depth of anesthesia was assessed by needle insertion during blood collection and at the 10-minute interval by needle insertion into the epaxial musculature. After the anesthetic period, the fish were placed in 10 L of water for recovery. Neither the water pH nor the temperature was affected by the addition of alfaxalone. The anesthesia induction period lasted a median 6.3 minutes and 5.2 minutes for the 1 mg/L and 2.5 mg/L maintenance trials, respectively. At the 20-minute point after induction, opercular movement was significantly less for fish exposed to 2.5 mg/L, but heart rates did not differ between the 2 maintenance doses. Opercular movement decreased significantly by the end of the induction period and stopped completely for 45 minutes in 4 of the 6 fish maintained on 2.5 mg of alfaxalone/L. However, all fish recovered after exposure to anesthesia-free
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water. Recovery times were significantly longer for the 2.5 mg/L trial than for the 1 mg/L trial (median ¼ 26.4 and 11.8 minutes, respectively). Response to noxious stimuli was 4/6 and 0/6 with the 1 and 2.5 mg/L maintenance doses, respectively. When compared with preanesthesia levels, blood pH was significantly decreased and blood bicarbonate and lactate levels were significantly increased during and after anesthesia with alfaxalone; however, values did not differ significantly between maintenance doses. The authors concluded that 10 mg of alfaxalone/L delivered by water immersion provided rapid and reliable induction in koi. Anesthesia resulting from a dose of 1 mg of alfaxalone/L may be sufficient only for venipuncture, sample collection, or diagnostic imaging, whereas a dose of 2.5 mg/L may be more appropriate for surgical procedures.
CONNIE ORCUTT, DVM, Dip. ABVP (Avian; Exotic Companion Mammals) Brookline, MA USA r 2015 Published by Elsevier Inc. 1557-5063/15/2101-$30.00 http://dx.doi.org/10.1053/j.jepm.2015.06.003
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