1
|
Bellone RR, Tanaka J, Esdaile E, Sutton RB, Payette F, Leduc L, Till BJ, Abdel-Ghaffar AK, Hammond M, Magdesian KG. A de novo 2.3 kb structural variant in MITF explains a novel splashed white phenotype in a Thoroughbred family. Anim Genet 2023; 54:752-762. [PMID: 37697831 DOI: 10.1111/age.13352] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 07/12/2023] [Accepted: 08/19/2023] [Indexed: 09/13/2023]
Abstract
Splashed white in horses is characterized by extensive white patterning on the legs, face and abdomen and may be accompanied by deafness. To date, seven variants in microphthalmia-associated transcription factor (MITF) and two variants in Paired Box 3 (PAX3) have been identified to explain this phenotype. A splashed white Thoroughbred stallion, whose sire and dam were not patterned, was hypothesized to have a de novo variant leading to his white coat pattern. A whole-genome sequencing candidate gene approach identified two single nucleotide variants (SNVs) in SOX10, four SNVs in MITF and a 2.3 kb deletion in MITF with the alternative allele present in this stallion but absent in the other 18 horses analyzed. All six SNVs were annotated as modifiers and were not further considered. The deletion in MITF (NC_009159.3:g.21555811_21558139delinsAAAT) encompasses exon 9 encoding a part of the helix-loop-helix domain required for DNA binding. Sanger sequencing and parentage testing confirmed that this deletion was a de novo mutation of maternal origin. Consistent with the published nomenclature, we denote this likely causal variant as SW8. Genotyping three of this stallion's offspring identified SW8 only in the nearly all-white foal that was confirmed deaf by brainstem auditory evoked response testing. This foal was also a compound heterozygote for dominant white variants (W20/W22), but to date, W variants alone have not been connected to deafness. SW8 marks the fourth de novo MITF variant in horses reported to cause white patterning. The link between deafness and all MITF variants with and without other variants impacting melanocyte development and function needs to be further explored.
Collapse
Affiliation(s)
- R R Bellone
- Veterinary Genetics Laboratory, School of Veterinary Medicine, UC Davis, Davis, California, USA
- Department of Population Health and Reproduction, School of Veterinary Medicine, UC Davis, Davis, California, USA
| | - J Tanaka
- Veterinary Genetics Laboratory, School of Veterinary Medicine, UC Davis, Davis, California, USA
| | - E Esdaile
- Veterinary Genetics Laboratory, School of Veterinary Medicine, UC Davis, Davis, California, USA
| | - R B Sutton
- Cell Physiology and Molecular Biophysics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - F Payette
- Department of Clinical Studies, New Bolton Center, University of Pennsylvania School of Veterinary Medicine, University School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA
| | - L Leduc
- Department of Clinical Studies, New Bolton Center, University of Pennsylvania School of Veterinary Medicine, University School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA
| | - B J Till
- Veterinary Genetics Laboratory, School of Veterinary Medicine, UC Davis, Davis, California, USA
| | - A K Abdel-Ghaffar
- Veterinary Genetics Laboratory, School of Veterinary Medicine, UC Davis, Davis, California, USA
| | - M Hammond
- Veterinary Genetics Laboratory, School of Veterinary Medicine, UC Davis, Davis, California, USA
- Department of Population Health and Reproduction, School of Veterinary Medicine, UC Davis, Davis, California, USA
| | - K G Magdesian
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| |
Collapse
|
2
|
Abstract
The vestibular system (VS) is the primary specialized sensory system responsible for maintaining balance (equilibrium) and orientation of the eyes, neck, trunk, and limbs during rest and movement. Two important reflexes are responsible for maintaining balance: vestibulo-ocular and vestibulospinal reflexes. These reflexes involve peripheral and central components of the VS. Whether central or peripheral disease, most of the disorders of the VS result in ipsilateral neurologic deficits. A few uncommon exceptions present with contralateral signs to the site of the lesion. This article provides a brief review of functional anatomy, vestibular disease, clinical signs, and examples of disorders affecting the VS.
Collapse
Affiliation(s)
- Monica Aleman
- SVM: Department of Medicine and Epidemiology, University of California, Tupper Hall 2108, One Shields Avenue, Davis, CA 95616, USA.
| |
Collapse
|
3
|
Aleman M, Crowe C, Dechant J, Bellone RR, Avila F. Brainstem auditory evoked responses and bone conduction assessment in alpacas. Res Vet Sci 2021; 136:297-302. [PMID: 33740564 DOI: 10.1016/j.rvsc.2021.02.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 02/26/2021] [Indexed: 11/18/2022]
Abstract
Auditory loss has been reported in camelids using brainstem auditory evoked responses (BAER). Differentiation between conductive versus sensorineural dysfunction has not been investigated. Therefore, the objective of the study was to investigate auditory function using BAER and bone conduction (BC). Twenty-four alpacas: 15 females, 9 intact males (2-16 years of age) were included in a randomized clinical trial. BAER and BC were recorded using two derivations (vertex to mastoid and vertex to cranial aspect of second cervical vertebra). All alpacas underwent complete physical examinations and were sedated with xylazine hydrochloride at 0.6 mg/kg IM. Peaks, when present, were identified and latencies, amplitudes, and amplitude ratios were determined. Eleven alpacas had normal responses and 13 had auditory loss based on BAER. The latter consisted of complete absence of peaks bilaterally (n = 3), absence of peaks unilaterally (n = 1), delayed latencies bilaterally (n = 4), and delayed latencies unilaterally (n = 5). Distinct peaks on BC supported conductive auditory loss in 6 alpacas, difficult to interpret due to stimulus artifact and additional undefined peaks in 4, and absent peaks in 3 alpacas. The cause of auditory loss was presumed to be due to otitis in 6, aging in 4 (10-16 years old), and congenital sensorineural (absent peaks on BAER and BC) in 3 alpacas with unpigmented fiber and irises. BAER and BC are useful and non-invasive to perform techniques for the investigation of auditory loss in alpacas, and further characterization as conductive or sensorineural.
Collapse
Affiliation(s)
- M Aleman
- Department of Medicine and Epidemiology, University of California, Davis, USA; School of Veterinary Medicine, University of California, Davis, USA.
| | - C Crowe
- The William R. Pritchard Veterinary Medical Teaching Hospital, University of California, Davis, USA; School of Veterinary Medicine, University of California, Davis, USA
| | - J Dechant
- Department of Surgical and Radiological Sciences, University of California, Davis, USA; School of Veterinary Medicine, University of California, Davis, USA
| | - R R Bellone
- Veterinary Genetics Laboratory, University of California, Davis, USA; Department of Population Health and Reproduction, University of California, Davis, USA; School of Veterinary Medicine, University of California, Davis, USA
| | - F Avila
- Veterinary Genetics Laboratory, University of California, Davis, USA; School of Veterinary Medicine, University of California, Davis, USA
| |
Collapse
|
4
|
Racine J, O'Brien T, Bladon BM, Cruz AM, Stoffel MH, Haenssgen K, Rodgerson DH, Livesey MA, Koch C. Ceratohyoidectomy in standing sedated horses. Vet Surg 2019; 48:1391-1398. [PMID: 31469435 DOI: 10.1111/vsu.13319] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 06/14/2019] [Accepted: 08/08/2019] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To investigate the feasibility and complications associated with ceratohyoidectomy (CHE) in standing sedated horses unaffected (experimental horses) and standing sedated horses affected (clinical cases) with temporohyoid osteoarthropathy (THO). STUDY DESIGN Case series. ANIMALS Six experimental horses and four clinical cases. METHODS Standing CHE was performed in six experimental horses euthanized 30 minutes (n = 3) and 7 days (n = 3) postoperatively. The four clinical cases were presented because of central facial nerve paralysis (n = 3), vestibular ataxia (n = 3), auricular hemorrhage (n = 2), quidding (n = 1), and oesophageal impaction (n = 1). Evolution was assessed by clinical examination during hospitalization and later by telephone interviews for the clinical cases. RESULTS The procedure was successfully performed in all horses. Experimental horses did not show any short-term postoperative complications. Hemorrhage was experienced intraoperatively in one of the clinical cases and was successfully managed with placement of hemostatic forceps. Vestibular ataxia and other symptoms of THO improved within days, but facial nerve paralysis did not improve until 9 days to 6 months after surgery. Follow-up ranged from 9 to 24 months. All clinical cases returned to performance, and client satisfaction was excellent. CONCLUSION Ceratohyoidectomy was consistently feasible in standing sedated horses. The method did not result in postoperative complications and led to resolution of clinical signs associated with THO. CLINICAL SIGNIFICANCE Standing CHE should be considered in horses affected with THO, especially when horses present with marked vestibular deficits and ataxia, to reduce risks associated with recovery from general anesthesia.
Collapse
Affiliation(s)
- Julien Racine
- Department of Equine Surgery, Swiss Institute for Equine Medicine, University of Bern, Bern, Switzerland
| | - Thomas O'Brien
- Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin
| | - Bruce M Bladon
- Donnington Grove Veterinary Surgery, Oxford Road, Newbury, United Kingdom
| | - Antonio M Cruz
- Department of Equine Surgery, Swiss Institute for Equine Medicine, University of Bern, Bern, Switzerland
| | - Michael H Stoffel
- Department of Veterinary Anatomy, Swiss Institute for Equine Medicine, University of Bern, Bern, Switzerland
| | - Kati Haenssgen
- Department of Veterinary Anatomy, Swiss Institute for Equine Medicine, University of Bern, Bern, Switzerland
| | - Dwayne H Rodgerson
- Davidson Surgical Center, Hagyard Equine Medical Institute, Lexington, Kentucky
| | - Michael A Livesey
- Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin
| | - Christoph Koch
- Department of Equine Surgery, Swiss Institute for Equine Medicine, University of Bern, Bern, Switzerland
| |
Collapse
|
5
|
Tanner J, Spriet M, Espinosa-Mur P, Estell KE, Aleman M. The prevalence of temporal bone fractures is high in horses with severe temporohyoid osteoarthropathy. Vet Radiol Ultrasound 2018; 60:159-166. [DOI: 10.1111/vru.12702] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Revised: 08/09/2018] [Accepted: 08/28/2018] [Indexed: 11/28/2022] Open
Affiliation(s)
- Jacqui Tanner
- School of Veterinary Medicine; University of California-Davis; Davis California
| | - Mathieu Spriet
- School of Veterinary Medicine; University of California-Davis; Davis California
| | - Pablo Espinosa-Mur
- School of Veterinary Medicine; University of California-Davis; Davis California
| | - Krista E. Estell
- School of Veterinary Medicine; University of California-Davis; Davis California
| | - Monica Aleman
- School of Veterinary Medicine; University of California-Davis; Davis California
| |
Collapse
|
6
|
Espinosa P, Nieto JE, Estell KE, Kass PH, Aleman M. Outcomes after medical and surgical interventions in horses with temporohyoid osteoarthropathy. Equine Vet J 2017; 49:770-775. [DOI: 10.1111/evj.12701] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Accepted: 05/12/2017] [Indexed: 11/27/2022]
Affiliation(s)
- P. Espinosa
- William R. Pritchard Veterinary Medical Teaching Hospital; School of Veterinary Medicine; University of California Davis; Davis California USA
| | - J. E. Nieto
- Department of Surgical and Radiological Sciences; School of Veterinary Medicine; University of California Davis; Davis California USA
| | - K. E. Estell
- Department of Medicine and Epidemiology; School of Veterinary Medicine; University of California Davis; Davis California USA
| | - P. H. Kass
- Department of Population Health and Reproduction; School of Veterinary Medicine; University of California Davis; Davis California USA
| | - M. Aleman
- Department of Medicine and Epidemiology; School of Veterinary Medicine; University of California Davis; Davis California USA
| |
Collapse
|
7
|
Diseases of the Nervous System. Vet Med (Auckl) 2017. [PMCID: PMC7322266 DOI: 10.1016/b978-0-7020-5246-0.00014-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
8
|
Computed Tomographic Features of the Osseous External Ear Canal, Tympanic Membrane, and Tympanic Bulla in Clinically Normal Horses. J Equine Vet Sci 2016. [DOI: 10.1016/j.jevs.2016.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
9
|
Konold T, Phelan LJ, Cawthraw S, Simmons MM, Chaplin MJ, González L. Abnormalities in Brainstem Auditory Evoked Potentials in Sheep with Transmissible Spongiform Encephalopathies and Lack of a Clear Pathological Relationship. Front Vet Sci 2016; 3:60. [PMID: 27532040 PMCID: PMC4969942 DOI: 10.3389/fvets.2016.00060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 07/14/2016] [Indexed: 11/13/2022] Open
Abstract
Scrapie is transmissible spongiform encephalopathy (TSE), which causes neurological signs in sheep, but confirmatory diagnosis is usually made postmortem on examination of the brain for TSE-associated markers like vacuolar changes and disease-associated prion protein (PrP(Sc)). The objective of this study was to evaluate whether testing of brainstem auditory evoked potentials (BAEPs) at two different sound levels could aid in the clinical diagnosis of TSEs in sheep naturally or experimentally infected with different TSE strains [classical and atypical scrapie and bovine spongiform encephalopathy (BSE)] and whether any BAEP abnormalities were associated with TSE-associated markers in the auditory pathways. BAEPs were recorded from 141 clinically healthy sheep of different breeds and ages that tested negative for TSEs on postmortem tests to establish a reference range and to allow comparison with 30 sheep clinically affected or exposed to classical scrapie (CS) without disease confirmation (test group 1) and 182 clinically affected sheep with disease confirmation (test group 2). Abnormal BAEPs were found in 7 sheep (23%) of group 1 and 42 sheep (23%) of group 2. The proportion of sheep with abnormalities did not appear to be influenced by TSE strain or PrP(Sc) gene polymorphisms. When the magnitude of TSE-associated markers in the auditory pathways was compared between a subset of 12 sheep with and 12 sheep without BAEP abnormalities in group 2, no significant differences in the total PrP(Sc) or vacuolation scores in the auditory pathways could be found. However, the data suggested that there was a difference in the PrP(Sc) scores depending on the TSE strain because PrP(Sc) scores were significantly higher in sheep with BAEP abnormalities infected with classical and L-type BSE, but not with CS. The results indicated that BAEPs may be abnormal in sheep infected with TSEs but the test is not specific for TSEs and that neither vacuolation nor PrP(Sc) accumulation appears to be responsible for the clinical abnormalities.
Collapse
Affiliation(s)
- Timm Konold
- Animal Sciences Unit, Animal and Plant Health Agency, Weybridge, Addlestone, UK
| | - Laura J. Phelan
- Animal Sciences Unit, Animal and Plant Health Agency, Weybridge, Addlestone, UK
| | - Saira Cawthraw
- Central Sequencing Unit, Animal and Plant Health Agency, Weybridge, Addlestone, UK
| | - Marion M. Simmons
- Pathology Department, Animal and Plant Health Agency, Weybridge, Addlestone, UK
| | - Melanie J. Chaplin
- Pathology Department, Animal and Plant Health Agency, Weybridge, Addlestone, UK
| | - Lorenzo González
- Pathology Department, Animal and Plant Health Agency, Lasswade, Penicuik, UK
| |
Collapse
|
10
|
Aleman M, Spriet M, Williams DC, Nieto JE. Neurologic Deficits Including Auditory Loss and Recovery of Function in Horses with Temporohyoid Osteoarthropathy. J Vet Intern Med 2015; 30:282-8. [PMID: 26513722 PMCID: PMC4913646 DOI: 10.1111/jvim.13654] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 08/24/2015] [Accepted: 09/28/2015] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Auditory loss is a common deficit in horses with temporohyoid osteoarthropathy (THO), however, recovery of function is unknown. HYPOTHESIS/OBJECTIVES To investigate neurologic function with emphasis in audition in horses with THO after treatment. To describe anatomical alterations of the petrous temporal bone that might result in auditory loss. ANIMALS Twenty-four horses with a clinical diagnosis of THO. METHODS Prospective study. A brainstem auditory evoked response (BAER) study was done as part of the criteria for inclusion in horses with a clinical diagnosis of THO from the years of 2005 to 2014. Physical and neurologic status and BAER findings were recorded. Brainstem auditory evoked response variables were compared by using Wilcoxon sign test. Fisher's exact test was also used. Significance was set at P < 0.05. RESULTS The most common signs included auditory loss (100% of horses), vestibular and facial nerve dysfunction (83%), and exposure ulcerative keratitis (71%). Concurrent left laryngeal hemiparesis was observed in 61% of horses through endoscopy. Auditory dysfunction was bilateral in 50% of the cases (complete and partial), and unilateral affecting more commonly the right ear (R = 8, L = 4). Short- and long-term follow-up revealed persistent auditory loss in all horses based on abnormal response to sound, and further confirmed through a BAER in 8 horses. CONCLUSIONS AND CLINICAL IMPORTANCE Auditory dysfunction appears to be a permanent neurologic deficit in horses diagnosed with THO despite overall neurologic improvement.
Collapse
Affiliation(s)
- M Aleman
- Department of Medicine and Epidemiology, University of California, Davis, CA
| | - M Spriet
- Department of Surgical and Radiological Sciences, University of California, Davis, CA
| | - D C Williams
- William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA
| | - J E Nieto
- Department of Surgical and Radiological Sciences, University of California, Davis, CA
| |
Collapse
|
11
|
Aleman M, Davis E, Williams DC, Madigan JE, Smith F, Guedes A. Electrophysiologic Study of a Method of Euthanasia Using Intrathecal Lidocaine Hydrochloride Administered during Intravenous Anesthesia in Horses. J Vet Intern Med 2015; 29:1676-82. [PMID: 26332487 PMCID: PMC4895652 DOI: 10.1111/jvim.13607] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 06/27/2015] [Accepted: 07/28/2015] [Indexed: 11/27/2022] Open
Abstract
Background An intravenous (IV) overdose of pentobarbital sodium is the most commonly used method of euthanasia in veterinary medicine. However, this compound is not available in many countries or rural areas resulting in usage of alternative methods such as intrathecal lidocaine administration after IV anesthesia. Its safety and efficacy as a method of euthanasia have not been investigated in the horse. Hypothesis/Objectives To investigate changes in mean arterial blood pressure and electrical activity of the cerebral cortex, brainstem, and heart during intrathecal administration of lidocaine. Our hypothesis was that intrathecal lidocaine affects the cerebral cortex and brainstem before affecting cardiovascular function. Animals Eleven horses requiring euthanasia for medical reasons. Methods Prospective observational study. Horses were anesthetized with xylazine, midazolam, and ketamine; and instrumented for recording of electroencephalogram (EEG), electrooculogram (EOG), brainstem auditory evoked response (BAER), and electrocardiogram (ECG). Physical and neurological (brainstem reflexes) variables were monitored. Mean arterial blood pressure was recorded throughout the study. Results Loss of cerebro‐cortical electrical activity occurred up to 226 seconds after the end of the infusion of lidocaine solution. Cessation of brainstem function as evidenced by a lack of brainstem reflexes and disappearance of BAER occurred subsequently. Undetectable heart sounds, nonpalpable arterial pulse, and extremely low mean arterial blood pressure supported cardiac death; a recordable ECG was the last variable to disappear after the infusion (300–1,279 seconds). Conclusions and Clinical Importance Intrathecal administration of lidocaine is an effective alternative method of euthanasia in anesthetized horses, during which brain death occurs before cardiac death.
Collapse
Affiliation(s)
- M Aleman
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA
| | - E Davis
- International Animal Welfare Training Institute, University of California, Davis, CA
| | - D C Williams
- The William R. Pritchard Veterinary Medical Teaching Hospital, University of California, Davis, CA
| | - J E Madigan
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA
| | - F Smith
- The William R. Pritchard Veterinary Medical Teaching Hospital, University of California, Davis, CA
| | - A Guedes
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA
| |
Collapse
|
12
|
Abstract
The most common disorders of the equine guttural pouches are empyema, tympany, mycosis, and temporohyoid osteoarthropathy. Diagnosis of these conditions is made primarily by imaging with endoscopy, radiographs, computed tomography, and/or MRI. Medical treatment with anti-inflammatories, antimicrobials, and/or antifungals may be successful in some cases, but many of these disorders necessitate surgical intervention. Direct surgical approaches to the guttural pouch are difficult because of their complex anatomy and relationship with important structures, thus precipitating a move toward minimally invasive procedures when possible.
Collapse
Affiliation(s)
- David E Freeman
- Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, 2015 SW. 16th Avenue, PO Box 100136, Gainesville, FL 32610, USA.
| |
Collapse
|
13
|
Effect of Xylazine, Detomidine, and Detomidine–Butorphanol Combination on Latencies of Peaks I–V of Brainstem Auditory–Evoked Responses in Horses. J Equine Vet Sci 2015. [DOI: 10.1016/j.jevs.2015.01.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
14
|
Aleman M, Williams DC, Guedes A, Madigan JE. Cerebral and brainstem electrophysiologic activity during euthanasia with pentobarbital sodium in horses. J Vet Intern Med 2015; 29:663-72. [PMID: 25800436 PMCID: PMC4895516 DOI: 10.1111/jvim.12570] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 12/18/2014] [Accepted: 02/04/2015] [Indexed: 11/28/2022] Open
Abstract
Background An overdose of pentobarbital sodium administered IV is the most commonly used method of euthanasia in veterinary medicine. Determining death after the infusion relies on the observation of physical variables. However, it is unknown when cortical electrical activity and brainstem function are lost in a sequence of events before death. Hypothesis/Objectives To examine changes in the electrical activity of the cerebral cortex and brainstem during an overdose of pentobarbital sodium solution for euthanasia. Our testing hypothesis is that isoelectric pattern of the brain in support of brain death occurs before absence of electrocardiogram (ECG) activity. Animals Fifteen horses requiring euthanasia. Methods Prospective observational study. Horses with neurologic, orthopedic, and cardiac illnesses were selected and instrumented for recording of electroencephalogram, electrooculogram, brainstem auditory evoked response (BAER), and ECG. Physical and neurologic (brainstem reflexes) variables were monitored. Results Loss of cortical electrical activity occurred during or within 52 seconds after the infusion of euthanasia solution. Cessation of brainstem function as evidenced by a lack of brainstem reflexes and disappearance of the BAER happened subsequently. Despite undetectable heart sounds, palpable arterial pulse, and mean arterial pressure, recordable ECG was the last variable to be lost after the infusion (5.5–16 minutes after end of the infusion). Conclusions and Clinical Importance Overdose of pentobarbital sodium solution administered IV is an effective, fast, and humane method of euthanasia. Brain death occurs within 73–261 seconds of the infusion. Although absence of ECG activity takes longer to occur, brain death has already occurred.
Collapse
Affiliation(s)
- M Aleman
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA, 95616
| | | | | | | |
Collapse
|
15
|
Aleman M, Holliday TA, Nieto JE, Williams DC. Brainstem auditory evoked responses in an equine patient population: part I--adult horses. J Vet Intern Med 2014; 28:1310-7. [PMID: 24902479 PMCID: PMC4857955 DOI: 10.1111/jvim.12379] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 04/04/2014] [Accepted: 04/22/2014] [Indexed: 01/24/2023] Open
Abstract
Background Brainstem auditory evoked response has been an underused diagnostic modality in horses as evidenced by few reports on the subject. Hypothesis/Objectives To describe BAER findings, common clinical signs, and causes of hearing loss in adult horses. Animals Study group, 76 horses; control group, 8 horses. Methods Retrospective. BAER records from the Clinical Neurophysiology Laboratory were reviewed from the years of 1982 to 2013. Peak latencies, amplitudes, and interpeak intervals were measured when visible. Horses were grouped under disease categories. Descriptive statistics and a posthoc Bonferroni test were performed. Results Fifty‐seven of 76 horses had BAER deficits. There was no breed or sex predisposition, with the exception of American Paint horses diagnosed with congenital sensorineural deafness. Eighty‐six percent (n = 49/57) of the horses were younger than 16 years of age. The most common causes of BAER abnormalities were temporohyoid osteoarthropathy (THO, n = 20/20; abnormalities/total), congenital sensorineural deafness in Paint horses (17/17), multifocal brain disease (13/16), and otitis media/interna (4/4). Auditory loss was bilateral and unilateral in 74% (n = 42/57) and 26% (n = 15/57) of the horses, respectively. The most common causes of bilateral auditory loss were sensorineural deafness, THO, and multifocal brain disease whereas THO and otitis were the most common causes of unilateral deficits. Conclusions and Clinical Importance Auditory deficits should be investigated in horses with altered behavior, THO, multifocal brain disease, otitis, and in horses with certain coat and eye color patterns. BAER testing is an objective and noninvasive diagnostic modality to assess auditory function in horses.
Collapse
Affiliation(s)
- M Aleman
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA
| | | | | | | |
Collapse
|
16
|
Aleman M, Madigan JE, Williams DC, Holliday TA. Brainstem auditory evoked responses in an equine patient population. Part II: foals. J Vet Intern Med 2014; 28:1318-24. [PMID: 24903742 PMCID: PMC4857935 DOI: 10.1111/jvim.12377] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 04/04/2014] [Accepted: 04/22/2014] [Indexed: 11/28/2022] Open
Abstract
Background Reports of the use of brainstem auditory evoked response (BAER) as a diagnostic modality in foals have been limited. Hypothesis/Objectives To describe BAER findings and associated causes of hearing loss in foals. Animals Study group 18 foals (15 neonatal, 3 nonneonatal), control group (5 neonatal foals). Methods Retrospective. BAER records from the Clinical Neurophysiology Laboratory were reviewed from the years of 1982 to 2013. Peak latencies, amplitudes, and interpeak intervals were measured when visible. Clinical data were extracted from the medical records. Foals were grouped under disease categories. Descriptive statistics were performed. Results Ten neonatal foals had complete absence of BAER bilaterally and 5 had findings within reference range. Abnormalities were associated with common neonatal disorders such as sepsis, neonatal encephalopathy, neonatal isoerythrolysis, and prematurity. BAER loss also was observed in foals with specific coat color patterns such as completely or mostly white with blue irides or lavender with pale yellow irides. An American Miniature foal with marked facial deformation also lacked BAER bilaterally. One nonneonatal foal with an intracranial abscess had no detectable BAER peaks bilaterally, and 2 older foals, 1 with presumed equine protozoal myeloencephalitis and the other with progressive scoliosis and ataxia, had BAER within normal limits. Conclusions and Clinical Importance In neonatal foals, BAER deficits commonly are complete and bilateral, and associated with common neonatal disorders and certain coat and eye color patterns. Sepsis, hypoxia, bilirubin toxicity, and prematurity should be investigated as potential causes of auditory loss in neonatal foals.
Collapse
Affiliation(s)
- M Aleman
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA
| | | | | | | |
Collapse
|
17
|
Affiliation(s)
- C. Koch
- ISME - Equine Clinic and Department of Clinical Veterinary Medicine; Vetsuisse-Faculty; University of Bern; Switzerland
| | - T. Witte
- Clinical Science and Services; Royal Veterinary College; Hatfield UK
| |
Collapse
|
18
|
Sommerauer S, Snyder A, Breuer J, Schusser GF. A Technique for Examining the External Ear Canal in Standing Sedated Horses. J Equine Vet Sci 2013. [DOI: 10.1016/j.jevs.2013.04.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
19
|
Mc BREARTY A, AUCKBURALLY A, POLLOCK PJ, PENDERIS J. Evoked otoacoustic emissions: An alternative test of auditory function in horses. Equine Vet J 2012; 45:60-5. [DOI: 10.1111/j.2042-3306.2011.00542.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
20
|
Palus V, Bladon B, Brazil T, Cherubini GB, Powell SE, Greet TRC, Marr CM. Retrospective study of neurological signs and management of seven English horses with temporohyoid osteoarthropathy. EQUINE VET EDUC 2011. [DOI: 10.1111/j.2042-3292.2011.00334.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
21
|
Rand CL, Hall TL, Aleman M, Spier SJ. Otitis media-interna and secondary meningitis associated with Corynebacterium pseudotuberculosis infection in a horse. EQUINE VET EDUC 2011. [DOI: 10.1111/j.2042-3292.2011.00273.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
22
|
Wilson WJ, Mills PC, Dzulkarnain AA. Use of BAER to identify loss of auditory function in older horses. Aust Vet J 2011; 89:73-6. [PMID: 21323652 DOI: 10.1111/j.1751-0813.2010.00682.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To use the brainstem auditory evoked response (BAER) to test the hypothesis that auditory function could be worse in older horses than in younger horses. PROCEDURE BAER waveforms in response to click stimuli were measured in five younger horses (5-8 years) and four older horses (17-22 years). RESULTS Compared with the younger horses, the older horses showed significantly (P < 0.02) worse BAER thresholds and significantly (P < 0.02) worse BAER wave V amplitudes to the 90 decibels above normal hearing level stimulus. These results were consistent with partial deafness in the older horse group. CONCLUSION BAER assessment can be used to identify partial deafness in older horses. Such horses should be managed appropriately, with particular care taken in noisy environments where hearing loss could put the horse and/or its owner at risk of harm.
Collapse
Affiliation(s)
- W J Wilson
- Division of Audiology, School of Health and Rehabilitation Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia.
| | | | | |
Collapse
|
23
|
Naylor RJ, Perkins JD, Allen S, Aldred J, Draper E, Patterson-Kane J, Piercy RJ. Histopathology and computed tomography of age-associated degeneration of the equine temporohyoid joint. Equine Vet J 2010; 42:425-30. [PMID: 20636779 DOI: 10.1111/j.2042-3306.2010.00036.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
REASONS FOR PERFORMING STUDY The aetiology of temporohyoid osteoarthropathy (THO) is unknown; both primary infectious and degenerative causes have been suggested. HYPOTHESIS There is a significant association between increasing age and severity of temporohyoid joint degeneration. To examine the histopathology of the temporohyoid articulation in aged horses and to compare the appearance of the joint with computed tomography (CT) and peripheral quantitative CT (pQCT). METHODS pQCT scans of the temporohyoid articulations were obtained bilaterally from 31 horses (range age 1-44 years) post mortem and images were graded by 2 blinded observers on 2 occasions for the presence of osteophytes, irregularity of the joint surface and mineralisation. Eight heads had been examined previously by CT, with the images similarly graded for the shape and density of the proximal stylohyoid bones, bone proliferation surrounding the joint, mineralisation of the tympanohyoid cartilage and the relationship of the petrous temporal bone to the stylohyoid bone. Sixteen temporohyoid joints were then evaluated histologically. RESULTS There was significant association between the mean pQCT degeneration score and age (rho = 0.75; P<0.0001), between the pQCT and CT score (rho = 0.63; P = 0.01) and between the degenerative changes identified within each temporohyoid joint within each horse (rho = 0.81; P<0.0001). Age-associated changes included the development of a club shape by the proximal stylohyoid bone, rounding of the synostosis with the petrous temporal bone and extension of osteophytes from the petrous temporal bone to envelope the stylohyoid head and bridge the joint. In no horse was there any evidence of osteomyelitis within the petrous temporal bone, stylohyoid bone or tympanohyoid cartilage. CONCLUSIONS This study provides evidence that age is associated with increasing severity of degenerative changes in the equine temporohyoid joint and that similar changes are commonly found bilaterally. POTENTIAL RELEVANCE The changes identified appear similar, albeit milder to the changes reported in horses with THO, suggesting that degenerative, rather than infectious causes may underlie the aetiology of THO. Future work should be directed at examining the histopathology of clinical THO cases.
Collapse
Affiliation(s)
- R J Naylor
- Department of Veterinary Clinical Sciences, The Royal Veterinary College, Hertfordshire; and Faculty of Veterinary Medicine, University of Glasgow, UK
| | | | | | | | | | | | | |
Collapse
|
24
|
Grenager NS, Divers TJ, Mohammed HO, Johnson AL, Albright J, Reuss SM. Epidemiological features and association with crib-biting in horses with neurological disease associated with temporohyoid osteoarthropathy (1991-2008). EQUINE VET EDUC 2010. [DOI: 10.1111/j.2042-3292.2010.00101.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
25
|
Magdesian KG, Williams DC, Aleman M, Lecouteur RA, Madigan JE. Evaluation of deafness in American Paint Horses by phenotype, brainstem auditory-evoked responses, and endothelin receptor B genotype. J Am Vet Med Assoc 2010; 235:1204-11. [PMID: 19912043 DOI: 10.2460/javma.235.10.1204] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate deafness in American Paint Horses by phenotype, clinical findings, brainstem auditory-evoked responses (BAERs), and endothelin B receptor (EDNBR) genotype. DESIGN Case series and case-control studies. ANIMALS 14 deaf American Paint Horses, 20 suspected-deaf American Paint Horses, and 13 nondeaf American Paint Horses and Pintos. PROCEDURES Horses were categorized on the basis of coat color pattern and eye color. Testing for the EDNBR gene mutation (associated with overo lethal white foal syndrome) and BAERs was performed. Additional clinical findings were obtained from medical records. RESULTS All 14 deaf horses had loss of all BAER waveforms consistent with complete deafness. Most horses had the splashed white or splashed white-frame blend coat pattern. Other patterns included frame overo and tovero. All of the deaf horses had extensive head and limb white markings, although the amount of white on the neck and trunk varied widely. All horses had at least 1 partially heterochromic iris, and most had 2 blue eyes. Ninety-one percent (31/34) of deaf and suspected-deaf horses had the EDNBR gene mutation. Deaf and suspected-deaf horses were used successfully for various performance events. All nondeaf horses had unremarkable BAER results. CONCLUSIONS AND CLINICAL RELEVANCE Veterinarians should be aware of deafness among American Paint Horses, particularly those with a splashed white or frame overo coat color pattern, blend of these patterns, or tovero pattern. Horses with extensive head and limb markings and those with blue eyes appeared to be at particular risk.
Collapse
Affiliation(s)
- K Gary Magdesian
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
| | | | | | | | | |
Collapse
|
26
|
Hilton H, Puchalski SM, Aleman M. The computed tomographic appearance of equine temporohyoid osteoarthropathy. Vet Radiol Ultrasound 2009; 50:151-6. [PMID: 19400460 DOI: 10.1111/j.1740-8261.2009.01508.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Equine temporohyoid osteoarthropathy is characterized by progressive osseous proliferation of the temporohyoid articulation and surrounding structures. The diagnosis has generally been made using radiography and endoscopy of the guttural pouch. Recently, computed tomography (CT) has been used in the diagnosis of temporohyoid osteoarthropathy. This study was performed to determine the CT imaging characteristics of temporohyoid osteoarthropathy and to compare these to radiographic and endoscopic findings. CT scans from 16 horses with a final diagnosis of temporohyoid osteoarthropathy were reviewed. Five horses that had undergone CT scan for reasons other than temporohyoid osteoarthropathy were included as controls. Qualitative and quantitative data were used to describe the magnitude of the CT findings. Osseous proliferation of the stylohyoid bone and temporohyoid articulation was found to be a consistent feature of temporohyoid osteoarthropathy. Thickening of the ceratohyoid bone and proliferation of its articulation with the stylohyoid bone was frequently identified and this finding may have surgical implications. Horses with neurologic deficits had increased stylohyoid width that was significantly different than the subclinically affected side. CT evaluation also allowed the identification of subclinical bilateral disease in horses thought to be unilaterally affected based on clinical examination.
Collapse
Affiliation(s)
- Hugo Hilton
- William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
| | | | | |
Collapse
|