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The objective of the study was to assess the neurotoxicity, using electrodiagnostic tests, of hydramethylnon (Amdro, AC 217,300), an insecticide marketed for the treatment of red imported fire ants, cockroaches, and other insects. Animals were male Fisher 344 albino rats and Long-Evans hooded rats. Brainstem auditory, visual, and somatosensory evoked potentials (BAER, VEP, SEP) and electroencephalograms (EEG) were recorded from implanted screw electrodes before and at multiple time points through day 10 after a single oral dose of hydramethylnon (at 50% or 75% of the LD50) plus vehicle, or vehicle alone. No evidence of nervous system toxicity was detected with either BAER, VEP, or SEP recordings. Spectral analysis of EEGs recorded over 7 days demonstrated a time-limited increase in power at low frequencies and decrease at high frequencies, reflecting a sedative effect. A dose-dependent weight loss was observed. Single-exposure poisonings with AC 217,300 can be expected to produce anorexia and CNS depression, but not lethality.

Pigment-associated deafness is a common hereditary condition in a range of dog breeds. The aim of this study was to perform a genome-wide association analysis to investigate the genetic architecture of deafness in Australian Cattle Dogs. Genotypes for 104 757 polymorphisms in 216 dogs were available for analyses after quality control. A genomic relationship matrix was used in the mixed model analyses to account for polygenic effects, as we tested each polymorphism for its association with deafness, in a case/control experimental design. Three approaches were used to code the genotypes and test for additive, recessive and dominant SNP effects. The genome-wide association study analyses identified a clear association peak on CFA20, with the most significant SNPs on this chromosome (1.29 × 10-4 ) in the vicinity of MITF. Variants in MITF have been associated with white pigmentation in dogs and with deafness in humans and other species, supporting the premise that canine deafness is associated with variants in or near this gene. A recessive inheritance for the peak in CFA20 is possible given the significant results in the recessive model; however, the estimated heritability was low (4.54 × 10-5 ). Further validation, identification of variants and testing in other dog breeds are needed.

Background The Dogo Argentino dog breed is affected by hereditary congenital sensorineural deafness (CSD) associated with white pigmentation, but prevalence data and associations with phenotypes have not been reported. Methods In a retrospective study, animals were tested by the brainstem auditory evoked response, and phenotype data of sex, iris color, patch presence/absence and parent hearing status were collected. Chi-square analyses were performed to identify associations between deafness and phenotype traits. Results BAER results and phenotype data were collected for 811 dogs. Hearing status was 74.23% bilaterally hearing, 20.35% unilaterally deaf and 5.43% bilaterally deaf or an overall prevalence of 25.77%. CSD was not associated with sex, but dogs without a patch had a significantly higher prevalence rate than patched dogs. Blue-eyed dogs had higher prevalence rates than brown-eyed dogs, but because of small sample size the χ2 association was not considered valid. Insufficient numbers of dogs with a unilaterally deaf parent were present to assess the effects of parent hearing status. Conclusion Approximately one fourth of a US Dogo Argentino population was deaf in one or both ears, but dogs with a patch had a lower prevalence. Dogs with a blue eye were more likely to be deaf, but the association significance could not be reliably assessed.

Recordings of distortion product otoacoustic emissions (DPOAE) were taken from 28 geriatric dogs aged 12.2 ± 2.2 years and 15 control dogs aged 5.9 ± 3.0 years (mean ± standard deviation) to demonstrate frequency-specific changes in cochlear responses. Recordings were performed for primary frequencies of 2-12 kHz in 2 kHz increments. Brainstem auditory evoked response (BAER) recordings were also made from geriatric dogs for comparison with DPOAE responses. Significant decreases in DPOAE response amplitudes were observed at frequencies of 6-12 kHz in geriatric dogs compared to control dogs, reflecting loss of cochlear outer hair cells along the length of the cochlea. Significant decreases in response amplitudes were not seen at frequencies of 2 or 4 kHz. Decreases in BAER response amplitudes subjectively paralleled the depressed DPOAE amplitudes. No significant linear regression relationships were found for DPOAE response amplitude vs. age despite the progressive nature of age-related hearing loss. The reductions in response at all frequencies starting at the age where dogs are considered geriatric indicate that age-related hearing loss begins earlier in the life span. DPOAE recordings provide a means to assess cochlear function across different portions of the auditory spectrum for assessing hearing loss associated with aging, and potentially for losses from other causes of decreased auditory function.

6-week-old, Arabian-cross male foal was referred to the Veterinary Teaching Hospital at the Louisiana State University School of Veterinary Medicine for a 1-week history of progressive weakness and intermittent right thoracic limb lameness. The foal had a normal birth, was healthy, had been active, and had not exhibited any abnormalities of gait before presentation. The current owner had acquired the mare just before foaling. The foal presented in sternal recumbency and was unable to rise without assistance. Physical examination identified a quiet, moderately responsive foal with dull mentation and body weight of 64 kg. Rectal temperature was 101.0°F, heart rate was 64 beats/min, and respiratory rate was 28 breaths/min. Mucous membranes were tacky, there was mild decreased skin turgor, and capillary refill time (CRT) was 2 seconds. There was a grade II/VI holosystolic murmur over the left heart base that was considered functional. Increased bronchovesicular sounds were present bilaterally. Lameness (grade 1/5) was evident in the right thoracic limb with pain on palpation and manipulation of the caudal aspect of the distal phalangeal and elbow joints. The lameness resolved after injection of lidocaine (Lidocaine 2%, VetOne a ) (2,000 U) into the elbow joint. Joint fluid analysis and radiographs of the distal phalangeal and elbow joints were considered normal. Spinal radiographs, evaluated because of rear limb weakness, also were considered normal. Radiographs of the thorax disclosed ventral alveolar opacities, consistent with aspiration pneumonia. The foal was somnolent on neurological examination and in sternal recumbency, but when assisted it/he could stand and walk. The lower lip drooped bilaterally and the palpebral fissures were decreased bilaterally because of upper eyelid ptosis. Normal palpebral reflexes were

Objective—To evaluate physical methods for inducing death during the slaughter of American alligators (Alligator mississippiensis). Animals—24 captive hatched-and-reared American alligators. Procedures—Baseline electroencephalograms (EEGs) were obtained for awake and anesthetized alligators. Corneal reflex, spontaneous blinking, and EEGs were evaluated after severance of the spinal cord, severance of the spinal cord followed by pithing of the brain, application of a penetrating captive bolt, or application of a nonpenetrating captive bolt (6 alligators/group). Results—Overall, alligators subjected to spinal cord severance alone differed from those subjected to the other techniques. Spinal cord severance alone resulted in postprocedure EEG power values greater than those in anesthetized alligators, whereas the postprocedure EEG power values were isoelectric for the other 3 techniques. Corneal reflex and spontaneous blinking were absent in all alligators immediately after application of a penetrating or nonpenetrating captive bolt. One of 6 alligators had a corneal reflex up to 1 minute after pithing, but all others within that group had immediate cessation of reflexes after pithing. Mean time to loss of spontaneous blinking and corneal reflex for alligators subjected to spinal cord severance alone was 18 minutes (range, 2 to 37 minutes) and 54 minutes (range, 34 to 99 minutes), respectively. Conclusions and Clinical Relevance—Spinal cord severance followed by pithing of the brain and application of a penetrating or nonpenetrating captive bolt appeared to be humane and effective techniques for inducing death in American alligators, whereas spinal cord severance alone was not found to be an appropriate method.

Recordings of distortion product otoacoustic emissions (DPOAEs) were taken from 15 geriatric cats (mean age ± standard deviation, SD, 13.6 ± 2.7 years; range 10.2-19.4 years) and 12 young adult control cats (mean ± SD 4.6 ± 0.5 years; range 3.4-5 years) to identify frequency-specific age-related changes in cochlear responses. Recordings were performed for primary frequencies from 2 to 12 kHz in 2 kHz increments. Cats were considered to be geriatric > 11.9 ± 1.9 years of age. Brainstem auditory evoked response (BAER) recordings were also made for subjective comparison with DPOAE responses. No differences in DPOAE response amplitudes were observed at any tested frequency in geriatric cats compared to control cats, reflecting an apparent absence of loss of cochlear outer hair cells along the length of the cochlea. No linear regression relationships were found for DPOAE response amplitude versus age in geriatric cats, despite the progressive nature of age-related hearing loss in other species. The absence of reductions in response at any of the tested frequencies in cats within the age span where cats are considered to be geriatric indicates that age-related hearing loss, if it does develop in cats, begins later in the life span of cats than in dogs or human beings.

Background: Deafness in dogs is frequently associated with the pigment genes piebald and merle. Little is known about the prevalence of deafness in dogs carrying the merle allele. Objective: To determine the prevalence of deafness in dogs heterozygous and homozygous for the merle allele of the mouse Silver pigment locus homolog (SILV) gene. Animals: One hundred and fifty-three privately owned merle dogs of different breeds and both sexes. Methods: Hearing was tested by brainstem auditory-evoked response and classified as bilaterally hearing, unilaterally deaf, or bilaterally deaf. DNA from buccal cells was genotyped as either heterozygous or homozygous for the merle allele. Deafness association tests among merle genotype, eye color, and sex were performed by the χ2 test. Results: Deafness prevalence in merles overall was 4.6% unilaterally deaf and 4.6% bilaterally deaf. There was a significant association between hearing status and heterozygous versus homozygous merle genotype. For single merles (Mm), 2.7% were unilaterally deaf and 0.9% were bilaterally deaf. For double merles (MM), 10% were unilaterally deaf and 15% were bilaterally deaf. There was no significant association with eye color or sex. Conclusions: Deafness prevalence in merle dogs was greater than that in some dog breeds homozygous for the piebald gene, such as the English Cocker Spaniel, but comparable to, or lower than, that in the Dalmatian and white Bull Terrier. Dogs homozygous for the merle allele were significantly more likely to be deaf than heterozygotes.

Hearing function was tested in dogs from breeds at risk for pigment-associated congenital sensorineural deafness - Dalmatian, English setter (ES), English cocker spaniel (ECS), bull terrier (BT), Australian cattle dog (ACD), whippet, Catahoula leopard dog, and Jack Russell terrier. Deafness prevalence was highest in Dalmatians and lowest in ECS. Phenotype correlation studies were performed in breeds with >100 brainstem auditory evoked responses (BAER) tested subjects. No gender differences were observed. No differences were seen between black- and liver-spotted Dalmatians, among the ES roan colour varieties, among the ECS parti varieties, or among the ACD colour varieties. Blue eyes were positively associated and patches were negatively associated with deafness in the Dalmatian. Blue eyes were also associated with deafness in the ES and ECS. White BT were more likely than coloured BT to be deaf. Having one or more parent's ear deaf was positively associated with deafness in Dalmatians, ES, and ECS.

Background Otitis externa is frequently accompanied by otitis media, yet it can be difficult to evaluate the tympanum, middle ear and auditory tube without the use of advanced radiographic imaging. Hypothesis/Objectives The objective was to develop techniques for tympanometry testing in conscious dogs and to present normative data for clinical use of this equipment to enable assessment of the tympanum, middle ear and auditory tube. Animals Sixteen hounds (14 female) from a school teaching colony. Methods Dogs were gently restrained in a standing position. After cleaning of the ear canal, a tympanometer probe tip extension was placed in the vertical canal and automated testing performed using a handheld device. Both ears were tested in all dogs. Results Acceptable recordings were obtained from both ears of 13 dogs, from one ear in each of two dogs and from neither ear of one dog, resulting in data from 28 of 32 (88%) ears. Otoscopic examination confirmed the absence of inflammation or any other obvious explanation for the noncompliant dogs. No significant differences were seen between ears for any measure. Normative data are reported for peak compliance, peak compliance pressure, gradient and ear canal volume. Conclusions and clinical importance Tympanograms can be recorded in conscious dogs to assist in the evaluation of the middle ear structures. Resume Contexte L'otite externe est frequemment accompagnee d'otite moyenne. Il est cependant difficile d’evaluer le tympan, l'oreille moyenne et la trompe d'Eustache sans l'aide de l'imagerie. Hypotheses/Objectifs L'objectif etait de developper les techniques de test de tympanometrie chez des chiens vigiles et de presenter des normes pour utilisation clinique de cet equipement afin de permettre l’evaluation du tympan, de l'oreille moyenne et de la trompe d'Eustache. Sujets Seize chiens (14 femelles) issus d'une colonie d'un etablissement d'enseignement. Methodes Les chiens etaient maintenus debout. Apres un nettoyage de l'oreille, une extension de la sonde d'un tympanometre a ete placee dans le canal vertical et les tests repetes ont ete realises a l'aide d'un appareil de poche. Les deux oreilles ont ete testees pour chaque chien. Resultats Les donnees satisfaisantes ont ete obtenues des deux oreilles de 13 chiens, d'une oreille de deux chiens et pour aucune oreille chez un chien, soit 28 sur 32 oreilles (88%). L'examen otoscopique a confirme l'absence d'inflammation ou de toute autre explication evidente pour les chiens non conformes. Aucune difference significative n'a ete observee entre les oreilles pour toute mesure. Les normes ont ete reportees pour les pics de compliance, la pression de compliance, le gradient et le volume du conduit auriculaire. Conclusions et importance clinique Les tympanogrammes peuvent etre enregistres chez des chiens vigiles afin d'aider l’evaluation des structures de l'oreille moyenne. Resumen Introduccion la otitis externa con frecuencia acompana a la otitis media, pero puede ser dificil de evaluar en el timpano, oido medio y conducto auditivo sin el uso de analisis de imagen radiografico avanzado. Hipotesis/Objetivos el objetivo de este estudio fue desarrollar tecnicas de timpanometria probadas en perros conscientes y presentar datos normativos para la el uso clinico de este equipo que permita la evaluacion del timpano, del oido medio y del conducto auditivo. Animales 16 perros de caza (14 hembras) de una colonia de una escuela. Metodos los perros fueron sujetos de pie sin forcejeo. Tras limpiar el canal auditivo se introdujo una prueba del timpanometro en el canal vertical y se procedio a una evaluacion automatica utilizando un aparato sostenido manualmente. Se evaluaron ambos oidos Resultados se obtuvieron parametros aceptables de ambos oidos en 13 perros y de un oido en cada uno de otros dos perros y en ningun oido en un perro, resultando en datos de 28 de en total de 32 (88%) oidos. El examen otoscopico confirmo la ausencia de inflamacion o cualquier otra explicacion obvia para los perros en los que no se pudieron obtener datos. No se observaron diferencias significativas en los oidos para ninguna de las mediciones. Se indican los datos normales para el pico de conformidad, presion del pico de conformidad, gradiente, y volumen de canal auditivo. Conclusiones e importancia clinica los timpanogramas pueden obtenerse en perros conscientes para ayudar a evaluacion de las estructuras del oido medio. Zusammenfassung Hintergrund Eine Otitis externa wird haufig von einer Otitis media begleitet, dennoch kann es schwierig sein, das Tympanum, das Mittelohr und den Gehorkanal ohne erweiterte bildgebende Diagnostik zu untersuchen. Hypothese/Ziele Das Ziel war es, eine Technik fur die Tympanometrie bei wachen Hunden zu entwickeln und normative Daten fur die Verwendung dieser Ausrustung zu prasentieren, die es moglich macht, das Tympanum, das Mittelohr und den Gehorkanal zu untersuchen. Tiere Sechzehn Jagdhunde (14 Hundinnen) aus einer Lehranstalt. Methoden Die Hunde wurden sanft in einer stehenden Position gehalten. Nach einer Reinigung des Ohrkanals wurde die Verlangerung einer Tympanometerspitze in den vertikalen Kanal platziert und eine automatisierte Untersuchung mittels handgehaltenem Griff durchgefuhrt. Bei allen Hunden wurden beide Ohren untersucht. Ergebnisse Es wurden von beiden Ohren von 13 Hunden, von einem Ohr bei zwei Hunden und von keinem Ohr bei einem Hund, akzeptable Messungen erzielt, was in Messungen von 28 der 32 (88%) Ohren resultierte. Die otoskopische Untersuchung bestatigte die Abwesenheit einer Entzundung sowie irgendeine andere Erklarung fur die Nicht-Compliance der Hunde. Es wurden bei keiner der Messungen signifikante Unterschiede zwischen den Ohren gesehen. Normative Ergebnisse wurden fur die maximale Compliance, die maximale Compliance des Drucks und das Ohrkanalvolumen beschrieben. Schlussfolgerungen und klinische Bedeutung Tympanogramme konnen bei wachen Hunden durchgefuhrt werden, um eine Evaluierung der Strukturen des Mittelohrs zu unterstutzen.

Objective: To examine the role of anticholinergic and sympathomimetic drugs in preventing gastric ulcerogenesis after cervical cord transection (CCT) in the rat. Methods: A randomized, prospective, interventional trial was performed comparing pirenzepine (muscarinic type I receptor antagonist) and ephedrine (nonspecific sympathomimetic) in the prevention of gastric ulcerogenesis after CCT in the rat. After isoflurane-induced general anesthesia, group 1 (n= 12) received sham CCT with no pretreatment, group 2 received CCT with no pretreatment, group 3 received CCT with pirenzepine pretreatment (0.01/mg/kg IP), and group 4 received CCT with ephedrine pretreatment (3 mg/kg IP). Six hours after intervention, all the rats were euthanized with isoflurane, stomachs were dissected, and a gastric ulcer index was determined. Results: The mean (± SD) ulcer index was 0.08 ± 0.1 for group 1, 2.33 ± 0.5 for group 2 (p = 0.01), 0.41 ± 0.7 for group 3 (p = 0.037 compared with group 2), and 0.75 ± 0.7 for group 4 (p = 0.0005 compared with group 2). Groups 3 and 4 were not significantly different from each other (p = 0.30). Conclusions: Gastric ulcerogenesis after CCT in the rat is decreased by anticholinergic and sympathomimetic drug pretreatment.

Visual system responses (visual evoked potentials) to flash (FVEP) and pattern reversal (PRVEP) stimuli were recorded in mice. Two strains were used: black C57BL/6J mice and agouti B6CBAF1/J mice (first generation offspring of C57BL/6J females and CBA/J males.) Subjects were sedated with ketamine and xylazine. Flash rate (FVEP) and stimulus spatial frequency and pattern reversal rate (PRVEP) were varied to determine optimum stimulus parameters. Normative FVEP and PRVEP data were collected from mice of both strains after determination of optimum parameters. Five positive and four negative alternating peaks were routinely observed in the FVEP, while three positive and three negative alternating peaks were seen with the PRVEP. Varying the flash rate, the pattern reversal rate, and spatial frequency significantly affected nearly all amplitude and latency measures in the responses. Significant differences between strains were seen on some, but not all, latency and amplitude measures when the stimulus parameters were varied.

Objective The present study was performed to document hearing loss in dogs and cats following procedures performed under anesthesia. Most cases of reported hearing loss were subsequent to dental and ear cleaning procedures. Study design Prospective and retrospective case survey. Animals Subjects were dogs and cats with deafness, personally communicated to one author, cases discussed on a veterinary information web site, and cases communicated through a survey of general practice and dental specialist veterinarians. Methods Reported deafness cases were characterized by species (dog, cat), breed, gender, age, and dog breed size. Results Sixty–two cases of hearing loss following anesthesia were reported between the years 2002 and 2009. Five additional cases were reported by survey respondents. Forty–three cases occurred following dental procedures. Sixteen cases occurred following ear cleaning. No relationship was observed between deafness and dog or cat breed, gender, anesthetic drug used, or dog size. Geriatric animals appeared more susceptible to post–anesthetic, post–procedural hearing loss. Conclusions Deafness may occur in dogs and cats following anesthesia for dental and ear cleaning procedures, but the prevalence is low. The hearing loss appears to be permanent. Clinical relevance Deafness can be a consequence following anesthesia for dental or ear cleaning procedures. Older animals may have greater susceptibility.

To screen for congenital deafness, brainstem auditory-evoked potential (BAEP) testing was performed on 1031 Dalmatians from three geographically separated areas. Phenotypic marker assessment was done to determine markers possibly associated with deafness. Markers included sex, hair coat color, pigmentation of different areas of skin (eye rims, nose, and ears), presence of a patch, spot size and marking (density of spotting), sire and dam BAEP status, and presence of iris and retinal tapetal pigmentation. Combined data from all test sites showed 8.1% bilateral deafness (N = 83 dogs) and 21.6% unilateral deafness (N = 223), or an overall 29.7% incidence of hearing disorders. Significant (P less than 0.05) associations with deafness for the data from all test sites combined were seen for patch, sire and dam BAEP, iris pigment, and retinal pigment. However, results differed for several of the significant phenotypic markers when analyses were done on the data from the individual test sites; changes from significant to not significant were found. This suggested the existence of multiple populations of deafness patterns, and reinforced the precautionary conclusion that associations of phenotypic markers with deafness are not necessarily functionally significant.

Hyperbaric oxygen effects on brown recluse spider (Loxosceles reclusa) envenomation in rabbits. Toxicon29, 989–996, 1991.—Human loxoscelism was modeled in albino rabbits by injection of brown recluse spider (Loxosceles reclusa) venom, and the effects of daily or twice-daily hyperbaric oxygen treatment on wound healing were investigated. Lesions similar to those seen in humans were produced in rabbits by intradermal injection of 200 μl of a venom extract (0.21 μg protein per μl), including edema and erythema, ischemia and cyanosis in the first 12 hr, extensive purpura by 24 hr, and crateriform ulcer formation by day four, with induration and eschar formation. Hyperbaric oxygen treatments, consisting of two atmospheres absolute (2 ATA) for 60 min, were applied daily (n = 8) or twice daily (n = 8), while control animals (n = 8) received no treatment. Treatments were initiated 72 hr after venom injection (day 3) to duplicate typical clinical treatment delays, and were administered for seven consecutive days. No significant effects of hyperbaric oxygen treatment on lesion healing were seen as measured by lesion area. However, histologic evaluation of wound tissue collected at euthanasia on day 24 showed clear differences between rabbits receiving twice-daily treatments and those receiving daily or no treatment. The former showed complete re-epithelization or slight ulceration, while the latter usually had necrotic cavities extending into the dermis, with myonecrosis and inflammatory cell accumulation. Thus, no superficial differences were seen between groups, but twice-daily treatments resulted in enhanced recovery at the histologic level.

Background The association between patterns of pigmentation and deafness in the dog has a long-documented history, with reports dating back over one hundred years. Long suspected of having a genetic basis, the search for loci with a pronounced influence in the expression of hearing loss in the dog has yet to be successful. No studies in the dog to date have found a possible influence of a specific colour locus associated with deafness. The present study is intended to evaluate the heritability of deafness in the Jack Russell Terrier (JRT), characterize the mode of inheritance, and evaluate the existence of a sex, coat colour, or coat texture influence on the expression of sensorineural deafness. Results The estimation of heritability of deafness in the JRT was 0.22 when deafness was considered a binary (normal/deaf) trait and 0.31 when deafness was considered a three-category (normal/unilateral/bilateral deafness). The influence of coat colour in the incidence of JRT deafness was statistically significant, indicating that dogs with more white are more likely to be deaf. The influence of sex or coat texture was not statistically significant in the incidence of JRT deafness. Complex segregation analysis revealed a model of a single locus with a large effect on the binary measure of hearing loss is not supported. Conclusion This is the first attempt, to our knowledge, to characterize a genetic component responsible for deafness in the JRT. The heritability of deafness in the JRT was found to be 0.22 and 0.31 considering deafness to be a two-category or three-category trait, respectively. There appears to be an influence of coat colour on the expression of deafness. In an attempt to characterize the mode of inheritance of deafness in the JRT, a model of a single locus with a large effect on hearing loss is not supported with this data. Further study is needed to determine if a single locus may be influencing deafness in the JRT. While the absence of a clear mode of inheritance complicates genetic dissection of deafness in the JRT, the assembling of this pedigree provides a tool for eventually defining the genetic bases of this disorder.

Gastric ulcers are an important cause of morbidity and mortality in the critically ill, especially those with CNS injury. We used cervical spinal cord transection (CCT) in the rat to model these ulcers and examined the effect of core body temperature and vascular volume on gastric ulcerogenesis. Hypothermia significantly increased ulcerogenesis compared to euthermia, while maintained euthermia produced ulcer indices not different from sham surgery. Hypovolemia (10% blood volume withdrawal) significantly increased ulcerogenesis compared to hypervolemia (10% of blood volume crystalloid infusion) or sham surgery. These results support crystalloid infusion and maintenance of core body temperature in the clinical setting.

Objective—To determine functional and morphologic changes in palmar digital nerves after nonfocused extracorporeal shock wave (ESW) treatment in horses. Animals—6 horses. Procedures—The medial and lateral palmar digital nerves of the left forelimb were treated with nonfocused ESWs. The medial palmar digital nerve of the right forelimb served as a nontreated control nerve. At 3, 7, and 35 days after treatment, respectively, 2 horses each were anesthetized and nerves were surgically exposed. Sensory nerve conduction velocities (SNCVs) of treated and control nerves were recorded, after which palmar digital neurectomies were performed. Morphologic changes in nerves were assessed via transmission electron microscopy. Results—Significantly lower SNCV in treated medial and lateral nerves, compared with control nerves, was found 3 and 7 days after treatment. A significantly lower SNCV was detected in treated medial but not lateral nerves 35 days after treatment. Transmission electron microscopy of treated nerves revealed disruption of the myelin sheath with no evidence of damage to Schwann cell bodies or axons, 3, 7, and 35 days after treatment. Conclusions and Clinical Relevance—Nonfocused ESW treatment of the metacarpophalangeal area resulted in lower SNCV in palmar digital nerves. This effect likely contributes to the post-treatment analgesia observed in horses and may result in altered peripheral pain perception. Horses with preexisting lesions may be at greater risk of sustaining catastrophic injuries when exercised after treatment. (Am J Vet Res 2004;65:1714–1718)

Brainstem auditory evoked potentials (BAEP) and flash visual evoked potentials (VEP) were recorded from juvenile (5-7 weeks of age) and adult Vietnamese miniature pot-bellied pigs to provide normative data for clinical applications. BAEP responses were collected in response to stimulus intensities of 85, 95, and 105 dB nHL. VEP responses were collected in response to flashes of white light in a darkened room. Left-right ear and left-right eye responses did not differ significantly, and were combined for analysis, with each animal providing two data points for each response. BAEP responses in juvenile subjects were mature, and in all subjects showed the typical pattern of decreasing peak latencies and increasing peak amplitudes with increasing stimulus intensity. VEP responses in juvenile subjects were near to mature values, but the latencies still exceeded those of adults. Differences in response maturation between precocial and altricial species are discussed.

Hereditary loss of hearing affects many breeds of the domestic dog, but the Dalmatian has the highest prevalence. Approximately 30% are affected in the United States (U.S.) population. It is widely accepted that a relationship exists between deafness and pigmentation in the dog and also in other animals. While the Dalmatian exemplifies this relationship, the genetic origin and mode of inheritance of deafness in this breed are unknown. The goals of this study were to: (1) estimate the heritability of deafness in an extended kindred of U.S. Dalmatians and (2) determine, through complex segregation analysis, whether there is a major segregating locus that has a large effect on the expression of deafness. A kindred of 266 Dalmatians was assembled, of which 199 had been diagnosed using the brainstem auditory evoked response to determine auditory status. Of these, 74.4% (N = 148) had normal hearing, 18.1% (N = 36) were unilaterally deaf, and 7.5% (N = 15) were bilaterally deaf. A heritability of 0.73 was estimated considering deafness a dichotomous trait and 0.75 considering it as a trichotomous trait. Although deafness in the Dalmatian is clearly heritable, the evidence for the presence of a single major gene affecting the disorder is not persuasive.

Visual evoked potentials (VEP) in response to flashes of white light were recorded from 15 adult beagles of both sexes to provide a normative data base. Separate recordings were taken by stimulating each eye of every dog. Responses were recorded from a needle electrode placed over the nuchal crest referenced to an electrode just caudal to the eyes. Five positive and negative peaks were present in each VEP; P1, N1, P2, N2, and P3. Peak P2 was the most prominent. Mean (+/- standard deviation [SD]) latencies for peaks P1, N1, P2, N2, and P3 were 14.3 +/- 2.4, 29.2 +/- 2.2, 54.5 +/- 7.4, 78.0 +/- 13.1, and 98.1 +/- 12.6 msec, respectively. Peak-to-peak mean amplitudes ranged from 5.88 to 13.30 microV. Recordings were accomplished without sedation, anesthesia, or mydriatic drugs.

Brainstem auditory-evoked potentials (BAEP), electroretinograms (ERG), and visual-evoked potentials (VEP) were recorded for eight calves from birth to 56 days and the values compared with previously determined adult responses. The BAEPs, ERGs, and VEPs recorded within the first 24 hours after birth contained all of the peaks seen in adult recordings. Varying degrees of maturation of the responses were documented as changes in latency and amplitude with age. The BAEPs were adult-like at birth, with latencies falling within the mean, plus or minus one standard deviation, for adult cows. A small but significant decrease in latency with age was seen for the first, second, and fourth peaks of the response. The ERG amplitudes were also within the adult range for the entire period of the study. Latencies to the a- and b-waves declined during the first 14 days and then stabilized at adult values. The VEP latencies decreased with age, with late peaks changing more than early peaks. Latencies of all but the first peak decreased to values less than the adult range. Two VEP amplitudes increased significantly with age. Developmental patterns in the calf and other precocious species are compared to those in altricious (nonprecocious) species. (Journal of Veterinary Internal Medicine 1989; 3:231–237)

Chronic temporal lobe seizures were induced in 11 monkeys by bilateral implantation of aluminum hydroxide into the hippocampi. With unilateral temporal lobe implants of alumina little or no epileptic activity was found; however, with bilateral alumina implants clinical seizures similar to human psychomotor attacks were initiated in either of the affected temporal lobes. Spread of alumina through the ventricles and/or tissue in some animals resulted in other seizure types, most of which could be controlled by phenobarbital, without eliminating the temporal lobe seizures. The alumina temporal lobe seizures recurred spontaneously for indefinitely long periods; however, no monkey was studied longer than 14 months. The onset of seizure activity was followed by transient anorexia and adipsia which, with large alumina volumes or other debilitating factors, could progress to fatal status epilepticus. Histology revealed that tissue reactions to the alumina included cell loss, gliosis, and neovascularization, with the most severe reaction occurring adjacent to the alumina mass. Alumina which had leaked into the ventricles in some animals reentered the brain tissue at remote sites through the choroid plexus, resulting in multiple foci.