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Ben-Shlomo, G., Plummer, C., Barrie, K., & Brooks, D. (2012). Characterization of the normal dark adaptation curve of the horse. Veterinary Ophthalmology, 15(1), 42–45.
Abstract: Objective The goal of this work is to study the dark adaptation curve of the normal horse electroretinogram (ERG). Procedures The electroretinographic responses were recorded from six healthy female ponies using a contact lens electrode and a mini-Ganzfeld electroretinographic unit. The horses were sedated intravenously with detomidine, an auriculopalpebral nerve block was then performed, and the pupil was fully dilated. The ERG was recorded in response to a low intensity light stimulus (30 mcd.s/m2) that was given at times (T) T = 5, 10, 15, 20, 25, 30, 40, 50, and 60 min of dark adaptation. Off-line analysis of the ERG was then performed. Results Mean b-wave amplitude of the full-field ERG increased continuously from 5 to 25 min of dark adaptation. The b-wave amplitude peaked at T = 25, however, there was no statistical significance between T = 20 and T = 25. The b-wave amplitude then remained elevated with no significant changes until the end of the study at T = 60 (P > 0.49). The b-wave implicit time increased continuously between T = 5 and T = 20, then gradually decreased until T = 60. No distinct a-wave was observed during the testing time. Conclusions Evaluation of horse rod function or combined rod/cone function by means of full-field ERG should be performed after a minimum 20 min of dark adaptation.
Keywords: adaptation; curve; dark; electroretinography; equine; scotopic
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Crans, W. J., McNelly, J., Schulze, T. L., & Main, A. (1986). Isolation of eastern equine encephalitis virus from Aedes sollicitans during an epizootic in southern New Jersey. J Am Mosq Control Assoc, 2(1), 68–72.
Abstract: Eastern equine encephalitis virus (EEE) was isolated from the salt marsh mosquito, Aedes sollicitans, collected from coastal areas of New Jersey on 3 occasions during the late summer and fall of 1982. The isolations were made at a time when local Culiseta melanura were either undergoing a population increase or exhibiting high levels of EEE virus. Although no human cases were reported during the epizootic period, the data lend support to the hypothesis that Ae. sollicitans is capable of functioning as an epidemic vector in the coastal areas of New Jersey where human cases of EEE have been most common.
Keywords: Aedes/*microbiology; Alphavirus/*isolation & purification; Animals; Disease Outbreaks/veterinary; Ecology; Encephalitis Virus, Eastern Equine/*isolation & purification; Encephalomyelitis, Equine/epidemiology/transmission/veterinary; Horse Diseases/epidemiology/transmission; Horses; Insect Vectors/microbiology; New Jersey
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Hardy, J. L. (1987). The ecology of western equine encephalomyelitis virus in the Central Valley of California, 1945-1985. Am J Trop Med Hyg, 37(3 Suppl), 18s–32s.
Abstract: Reeves' concept of the summer transmission cycle of western equine encephalomyelitis virus in 1945 was that the virus was amplified in a silent transmission cycle involving mosquitoes, domestic chickens, and possibly wild birds, from which it could be transmitted tangentially to and cause disease in human and equine populations. Extensive field and laboratory studies done since 1945 in the Central Valley of California have more clearly defined the specific invertebrate and vertebrate hosts involved in the basic virus transmission cycle, but the overall concept remains unchanged. The basic transmission cycle involves Culex tarsalis as the primary vector mosquito species and house finches and house sparrows as the primary amplifying hosts. Secondary amplifying hosts, upon which Cx. tarsalis frequently feeds, include other passerine species, chickens, and possibly pheasants in areas where they are abundant. Another transmission cycle that most likely is initiated from the Cx. tarsalis-wild bird cycle involves Aedes melanimon and the blacktail jackrabbit. Like humans and horses, California ground squirrels, western tree squirrels, and a few other wild mammal species become infected tangentially with the virus but do not contribute significantly to virus amplification.
Keywords: Aedes/microbiology; Animals; Birds; California; Culex/microbiology; Encephalitis Virus, Western Equine/*physiology; Encephalomyelitis, Equine/*history/microbiology/transmission/veterinary; History, 20th Century; Horse Diseases/history/transmission; Horses; Humans; Insect Vectors/microbiology; Mammals
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Bertram, D. S. (1971). Mosquitoes of British Honduras, with some comments on malaria, and on arbovirus antibodies in man and equines. Trans R Soc Trop Med Hyg, 65(6), 742–762.
Keywords: Aedes; Animals; Anopheles; Antibodies/*analysis; Arbovirus Infections/*epidemiology/immunology/veterinary; Belize; Culex; *Culicidae/classification; Ecology; Encephalitis Virus, St. Louis/immunology; Encephalitis Virus, Venezuelan Equine/immunology; Horse Diseases/*epidemiology/immunology; Horses; Humans; Insect Vectors; Malaria/*epidemiology; Neutralization Tests; Seasons
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Spengler M.I., & Rasia M. (2001). Influence of Plasma Proteins on Erythrocyte Aggregation in Three Mammalian Species. Vet.Res.Comm, 25(7), 591–599.
Abstract: The aggregation capacity of human erythrocytes lies between that of the non-aggregating bovine erythrocytes and the remarkably aggregating equine ones. As the ability to aggregate is attributed to cell factors and the composition of the plasma proteins, the role that plasma proteins play in the aggregation process in these three species was studied. Washed erythrocytes were suspended in phosphate-buffered saline (PBS; pH 7.4, 300 mOsm/L) plus polyvinylpyrrolidone (PVP) in a suitable concentration to obtain an average intensity of aggregation (control media). The superimposed effect of replacing 80% of the medium by either autologous plasma, serum or albumin solution was studied. The plasma proteins appeared to enhance aggregation by human and equine erythrocytes, but impaired this process in bovine erythrocytes. Some evidence was obtained supporting the existence of serum factors capable of reducing aggregation of erythrocytes in cattle and it was concluded that the non-aggregating behaviour of bovine erythrocytes may be due to the cells interacting particularly with the macromolecules in the serum.
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McLean, A. N. (2004). Short-term spatial memory in the domestic horse. Appl. Anim. Behav. Sci., 85(1-2), 93–105.
Abstract: This study investigates the ability of horses to recall a feeding event in a two-point choice apparatus. Twelve horses were individually tested whereby they were maintained immobile in a test arena and visually and aurally experienced the delivery of food into one of two feed goals. The horses were then released to make their choice in two experimental contexts: immediate release after experiencing the delivery of food, and release 10 s after food delivery. Each horse performed 40 immediate-release (IR) trials, followed by forty 10-s release trials over a 3-day period. In addition, the same horses were tested 3 months later in the spring with the same number and sequence of trials. Results were analysed by log-linear analysis of frequencies. Results showed that while horses were able to achieve the correct feed goal choice in the immediate-release trials, they were unsuccessful with the 10-s release trials. This suggests that there are limitations in recall abilities in horses, in that they may not possess a prospective type of memory. There are welfare and training implications in these findings concerning the effects of overestimating the mental abilities of horses during training and the effects of delays in reinforcements.
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Burn, C. C., Dennison, T. L., & Whay, H. R. (2010). Relationships between behaviour and health in working horses, donkeys, and mules in developing countries. Appl. Anim. Behav. Sci., 126(3-4), 109–118.
Abstract: Recent studies raise serious welfare concerns regarding the estimated 93.6 million horses, donkeys and mules in developing countries. Most equids are used for work in poor communities, and are commonly afflicted with wounds, poor body condition, respiratory diseases, parasites, dental problems, and lameness. Non-physical welfare problems, such as fear of humans, are also of concern. Interventions to improve working equine welfare aim to prioritise the conditions that cause the most severe impositions on the animals' subjectively experienced welfare, but data identifying which conditions these may be, are lacking. Here we describe a stage in the validation of behavioural welfare indicators that form part of a working equine welfare assessment protocol. Over 4 years, behavioural and physical data were collected from 5481 donkeys, 4504 horses, and 858 mules across nine developing countries. Behaviours included the animals' general alertness, and their responses to four human-interaction tests, using the unfamiliar observer as the human stimulus. Avoidance behaviours correlated significantly with each other across the human-interaction tests, with 21% of animals avoiding the observer, but they showed no associations with likely anthropogenic injuries. Over 13% of equids appeared [`]apathetic': lethargic rather than alert. Measures of unresponsiveness correlated with each other across the five tests, and were associated with poor body condition, abnormal mucous membrane colour, faecal soiling, eye abnormalities, more severe wounds, and older age, depending on the equine species. This suggests that working equids in poor physical health show an unresponsive behavioural profile, consistent with sickness behaviour, exhaustion, chronic pain, or depression-like states.
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Strand, S. C., Tiefenbacher, S., Haskell, M., Hosmer, T., McDonnell, S. M., & Freeman, D. A. (2002). Behavior and physiologic responses of mares to short-term isolation. Appl. Anim. Behav. Sci., 78(2-4), 145–157.
Abstract: The aim of this study was to evaluate the behavior and physiologic responses of mares to removal from an established pasture herd and to isolation in a pasture setting for 6 h (Group I, n=5). Responses of mares in Group I were compared to mares that were transported and returned to the herd (Group T, n=5) and to mares moved to the isolation pasture with a companion (Group C, n=5). Behavior was recorded continuously for 6 h on the day before the isolation procedures (baseline, Day 0) and again on the day of the procedure (test, Day 1). Plasma cortisol, white blood cell count (WBC), neutrophil:lymphocyte ratio (N:L), and hematocrit (HCT) were measured once on Day 0 (a.m.) and twice on Day 1 (a.m. and p.m.). Heart rate (HR) was monitored continuously during Day 0 and Day 1. Intradermal response to phytohemagglutinin (PHA) injection was measured 18 h following injection, which was administered at the end of Day 1. Average time spent standing alert increased (P<0.05) in Groups I and C and average time spent grazing decreased (P<0.05) in Group C from Day 0 to Day 1. Also, there was a significant difference between groups (based on a calculated χ2-square value) in the proportion of mares that autogroomed, defecated, urinated, rolled, and whinnied on Day 1. Activity shift rate (ASR) and temperament scores increased significantly in Groups I and C from Day 0 to Day 1 (P<0.05). Plasma cortisol increased significantly in all groups from Day 0 to Day 1, a.m. (P<0.05) and decreased significantly from Day 1, a.m. to Day 1, p.m. (P<0.05). HCT significantly increased in all three groups from Day 0 to Day 1, a.m. (P<0.05). WBC significantly increased in Group T from Day 0 to Day 1, a.m. (P<0.05). N:L ratio significantly increased in Groups I and C from Day 0 and Day 1, a.m. to Day 1, p.m. (P<0.05). A variety of measures did indicate a response to removal from the pasture group, however, the overall, short-term response was minimal. Since the responses of Groups I and C were similar, the effects of isolation versus a novel environment or separation from the established herd could not be differentiated.
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Ogbourne, C. P. (1971). Variations in the fecundity of strongylid worms of the horse. Parasitology, 63(2), 289–298.
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Passler, S., & Pfeffer, M. (2003). Detection of antibodies to alphaviruses and discrimination between antibodies to eastern and western equine encephalitis viruses in rabbit sera using a recombinant antigen and virus-specific monoclonal antibodies. J Vet Med B Infect Dis Vet Public Health, 50(6), 265–269.
Abstract: Three arthropod-borne alphaviruses, western equine encephalitis viruses (WEEV), eastern equine encephalitis viruses (EEEV) and Venezuelan equine encephalitis viruses are the aetiological agents of a sometimes severe encephalomyelitis in equines and humans in the New World. With regard to the different ecology and epidemiology of these viruses, a method applied in serological screening should be able to distinguish between them as well as other related members of the genus Alphavirus in the American continent. However, this has been hampered in the past by (a) the close antigenic relationship between alphaviruses in traditional serological assays, especially in the routinely used haemagglutination-inhibition, and (b) the need of biosafety level 3 facilities to grow the viral antigens. An epitope blocking assay using an EEEV glycoprotein E1-expressing recombinant Sindbis virus and virus-specific monoclonal antibodies (mAbs) binding to the E1 of EEEV (strain NJ/60) and the E1 of Sindbis virus was established using automated flow cytometry. The test was evaluated using sera of infected and vaccinated rabbits. A cut-off value of 30% inhibition for antigenic complex-specific seroconversion was found to be sufficient for the detection of the respective infection. By using three different mAbs in parallel, we were able to detect alphavirus genus-, EEEV- and WEEV-complex-specific serum antibodies. As this test is based on the inhibition of binding of virus-specific mAbs, sera of every origin other than mouse can be tested. Thus, this assay may prove useful in the serological screening of a variety of animal species during an outbreak investigation.
Keywords: Animals; Antibodies, Monoclonal/*immunology; Antibodies, Viral/*analysis/blood; DNA Primers; Encephalitis Virus, Eastern Equine/genetics/*immunology; Encephalitis Virus, Western Equine/genetics/*immunology; Encephalomyelitis, Equine/*diagnosis/*virology; Epitopes; Fluorescent Antibody Technique/*veterinary; Horses; Rabbits; Recombination, Genetic; Reverse Transcriptase Polymerase Chain Reaction/veterinary
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