RESUMO
Infrared thermography has been used to help in diagnosing lameness. It is hypothesized that, if used in a routine basis, it could help in understanding musculoskeletal modifications during race training. This study aimed to evaluate thermal variation in the musculoskeletal regions of young Thoroughbred (TB) horses during their initial months of race training. Thermographic examinations were performed once every 2 weeks on 16 (10 male, 6 female) two-year-old TB racehorses, from arrival to the racetrack in June 2016, until January 2017, for a total of 16 evaluations. Thermographic imaging was performed using the appropriate protocol. Temperature (°C) was measured at the dorsal and palmar/plantar aspects of specific regions of interest (fetlock, metacarpal, metatarsal, carpal, tarsal, thoracolumbar, sacroiliac spine, and both hips). Initially, we found a thermal balance and all regions demonstrated a positive correlation with one another. However, a significant difference was noted between the left and right sides as training progressed. Four horses were withdrawn from the study after 50% of evaluations because of metacarpal conditions associated with training. Thermographic examination revealed changes before the clinical manifestation of these conditions. In conclusion, this study demonstrated that infrared thermography is an image technique that can facilitate understanding of musculoskeletal system modifications to race training and should be further investigated as a predictive tool to anticipate the occurrence of lesions.
Assuntos
Ossos Metacarpais , Ossos do Metatarso , Aclimatação , Animais , Feminino , Cavalos , Articulações , Masculino , Termografia/veterináriaRESUMO
The sloth's giant tick Amblyomma varium Koch, which is a neotropical species that inhabits tropical rainforests, is the largest tick reported to date. The adult stage of this tick parasitizes mammals from the families Bradypodidae and Magalonychidae (Xenarthra) nearly exclusively. This study aimed to describe morphological and histological features of the reproductive system and the oocyte maturation process of this tick species. The ovary of A. varium is a long single tubular organ that is horseshoe-shaped, winding and arranged in the posterior part of the body. Two oviducts are connected to the ovary on each side; these thicken at certain region forming the uterus (common oviduct), followed by a muscular connecting tube, vagina and genital aperture. A large number of oocytes at different stages of development are attached to the ovary wall by the pedicel, as they reach maturity they are released into the ovary lumen and from there to the genital aperture. These oocytes develop simultaneously and asynchronically along the ovary. Amblyomma varium oocytes were classified into five development stages (i.e., I-V), and specific characteristics were observed; the processes of yolk and chorion deposition begin early in oocytes stage II, and oocytes V exhibit a very thick chorion and eggs of a large size. These characteristics are likely adaptations that enhance the survival and the reproductive success of this extremely host-specific tick, which is limited to a particular environment.
Assuntos
Ixodidae/anatomia & histologia , Bichos-Preguiça/parasitologia , Animais , Brasil , Feminino , Histocitoquímica , Ixodidae/ultraestrutura , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Oócitos/ultraestrutura , Ovário/anatomia & histologiaRESUMO
Ovarian development and egg maturation are essential stages in animal reproduction. For bisexual ixodid ticks, copulation is an important prerequisite for the completion of the gonotrophic cycle. In this study, we aimed to characterize the morpho-histological changes in the ovary and oocytes of the tick Rhipicephalus sanguineus, together with the identification of feeding and reproductive parameters associated with mating. Virgin and cross-mated females (with R. turanicus males) weighed 60% less at full engorgement than females mated conspecifically. In addition, the oocytes of these females did not develop to the same advanced stages as those of the conspecifically mated females. Sequencing of a 250-bp ITS-2 fragment in eggs that originated from a cross between an R. sanguineus female and an R. turanicus male showed a genotype similar (except by a deletion of 1 thymine) to that observed in the mother, arguing against fertilization by a trans-specific male. These findings suggest that male sex peptides are species-specific molecules that influence both full engorgement and oocyte maturation. Mechanical stimulation of the gonopore alone was insufficient for the completion of the entire process of vitellogenesis.
Assuntos
Copulação , Ixodidae/fisiologia , Ovário/crescimento & desenvolvimento , Animais , Cruzamento , Feminino , Ixodidae/genética , Ixodidae/crescimento & desenvolvimento , Masculino , Oócitos/citologia , Oócitos/crescimento & desenvolvimento , Oócitos/metabolismo , Ovário/citologia , Ovário/metabolismo , Coelhos , Especificidade da Espécie , Espermatozoides/metabolismo , VitelogêneseRESUMO
Oocyte maturation in the thelytokous parthenogenetic tick Amblyomma rotundatum was examined for the first time using light and scanning electron microscopy. The panoistic ovary lacks nurse and follicular cells and is a single continuous tubular structure forming a lumen delimited by the ovarian wall. Oocytes of tick species are usually classified according to cytoplasm appearance, the presence of germinal vesicle, the presence of yolk granules, and the chorion. However, for this species, we also use oocyte size as an auxiliary tool since most oocytes were in stages I-III and were histologically very similar. Oocytes were classified into five development stages, and specific characteristics were observed: mature oocytes with thin chorion, pedicel cells arranged forming an epithelium with two or more oocytes attached by the same structure, and a large number of oocytes in the process of reabsorption.
Assuntos
Ixodidae/citologia , Oócitos/citologia , Animais , Feminino , Humanos , Ixodidae/crescimento & desenvolvimento , Ixodidae/ultraestrutura , Microscopia Eletrônica de Varredura , Oócitos/crescimento & desenvolvimento , Oócitos/ultraestrutura , Ovário/citologia , Partenogênese , VitelogêneseRESUMO
Histological features of Rhipicephalus sanguineus ticks fed on dog, a non resistant host, and on guinea pig, a resistant host, were compared. Unfed ticks and ticks from each host species were collected during first and third infestation and processed for histology. Many ticks from guinea pigs, especially during third infestation, were unattached, dehydrated and small. Only the midgut of ticks fed on guinea pigs had host leukocytes. Vacuolization of midgut cells was observed in all ticks, with exception of those fed on dogs for more than 96 h. Ticks of guinea pigs, particularly from third infestation, had vacuolated tracheae and swelling of malpighian tubules. Solely ticks from third infestation of guinea pigs displayed vacuolization of oocytes. Ticks fed on guinea pigs also had an increased number of guanine spherules. Observed alterations in ticks from guinea pigs are discussed.
Assuntos
Doenças do Cão/parasitologia , Rhipicephalus sanguineus/fisiologia , Infestações por Carrapato/veterinária , Animais , Cães , Feminino , Trato Gastrointestinal , Cobaias , Interações Hospedeiro-ParasitaRESUMO
Although Amblyomma brasiliense Aragão 1908 has been reported as one of the most aggressive ticks to humans in Brazil, information about the biology of this tick species is virtually inexistent. This work reports data on the life cycle of A. brasiliense fed on rabbits and pigs and maintained in an incubator at 20 degrees C, 90% RH and 12 h of light for off-host development. Tick yield of adult females fed on pigs and rabbits was 81.2% and 58.3%, respectively. Females fed on pigs had mean engorgement weight of 862.3 mg and egg mass of 208 mg, while females fed on rabbits had mean engorgement weight of 606.1 mg and egg mass of 160 mg; these values did not differ statistically between host species. Feeding period of female ticks fed on pigs (10 days) was significantly shorter than that on rabbits (17 days). Mean preoviposition period was slightly longer (35.9 days) for ticks fed on pigs than on rabbits (30 days). The minimum incubation period of eggs of ticks from both host species was similar and over 100 days. Egg production efficiency was low for females fed on both hosts (less than 30% and 20% for ticks from pigs and rabbits, respectively). More than 55% of larvae and 79% of nymphs fed on rabbits, set free inside the feeding chambers, engorged successfully. These ticks attained an engorgement weight of 1.3 and 18.2 mg, respectively, and fed for approximately 5 days. The minimum pre-molt period was 30 days for engorged larvae and over 44 days for nymphs. Molting success was low, less than 50% in the case of larvae and less than 20% for nymphs. Further studies are required to better determine the off-host requirements of this tick species.
Assuntos
Ixodidae/fisiologia , Ração Animal , Animais , Animais de Laboratório , Peso Corporal , Brasil/epidemiologia , Feminino , Humanos , Ixodidae/crescimento & desenvolvimento , Ixodidae/patogenicidade , Oviposição , Infestações por Carrapato/epidemiologiaRESUMO
This study investigated the development of resistance in guinea pigs to nymphs of Amblyomma triste ticks after repeated infestations. Guinea pigs were infested thrice, at 30-day intervals, with 30 nymphs of A. triste per animal per infestation. Acquisition of resistance was evaluated by determining: nymph yielding rate, engorgement period, and weight. Skin biopsies of tick bite sites were collected at 24, 48, and 96 h after tick attachment for inflammatory cell counts. Engorged nymphs weighed 5.53 mg +/- 1.9 in re-infested hosts (56.6% less than in primary infestation) and took 6.9 days +/- 2.16 to feed in the third infestation (14.5% more than in the first infestation). Guinea pigs yielded 78%+/- 7.2 of nymphs in the re-infestation (11.6% less than in the primary infestation). In addition, a marked increase in basophil influx was observed from the first infestation onward; 69% of infiltrated cells were basophils in re-infested hosts 24 h after tick attachment. No basophils were seen at this time in primary infested animals. That number increased to 84.7% 48 h post attachment in re-infested hosts (73.2% more than in the primary infested ones) and decreased markedly 96 h post attachment in both groups (2.6% and 1% of basophils in the third and first infestation, respectively). We conclude that guinea pigs acquire resistance against nymphs of A. triste ticks after repeated infestations and that a cutaneous basophilia must play a crucial role in such a mechanism.
Assuntos
Basófilos/imunologia , Dermatopatias/imunologia , Carrapatos/fisiologia , Animais , Basófilos/citologia , Feminino , Cobaias , Dermatopatias/patologiaRESUMO
The number of dermal mast cells in several European and Zebu cattle breeds was determined and correlated with the tick load. Breeds included European registered and non-registered Holstein, Brown-Swiss and Jersey cows, Zebu (Nelore and Gyr) and crossbred cows with either high or low tick infestations. Animals were naturally infested with Rhipicephalus (Boophilus) microplus and evaluated at regular time intervals for tick attachment and feeding. Ear biopsies were taken and processed according to routine histology for mast cell countings carried out on both the upper and deep dermis. The average cell counts were then correlated with the number of engorged ticks attached to host. Nelore cows presented the largest mast cells countings/mm2 (139.42; P <0.05), while surprisingly Gyr showed similar number of cells (61.73) as the Holstein (48.76) and Brown-Swiss (67.31) ones. Jersey cows presented the smallest cell countings (29.32) despite their greater resistance to tick infestation as compared to Holstein and Brown-Swiss. There was a negative correlation (r=-0.21, P <0.01) between the number of cells in the upper dermis and tick counts when all data (n= 155) were analyzed in a single correlation plane, irrespective of the breed. These results confirm the important role played by mast cells in bovine resistance to the cattle tick R. microplus.
Assuntos
Animais , Bovinos , Controle de Doenças Transmissíveis , Rhipicephalus/parasitologia , Mastócitos , Biópsia/veterináriaRESUMO
In this work, the biology, mitochondrial DNA and fertility of hybrids from two strains of Rhipicephalus sanguineus, from Brazil and Argentina, were compared. Engorged larvae, nymphs and adults from Argentina weighed more and the engorgement period of adult females was significantly longer than those of their Brazilian counterparts, whereas adult female tick yield rate was higher for the Brazilian strain. High intraspecific divergence of mitochondrial DNA was detected between R. sanguineus from Brazil and Argentina. On the other hand, a strong genetic relationship was detected between European and Argentinean R. sanguineus populations while the Brazilian population appeared to be related to the African Rhipicephalus turanicus. Adult hybrid females laid eggs, which were mostly unviable, whereas a mean of more than 1400 larvae hatched per egg mass from pure Brazilian and Argentinean strains. These results showed that differences between these strains are greater than previously assumed and that the biosystematic status of R. sanguineus ticks from South America should be re-evaluated. Wide variations, such as these might account for the reported worldwide differences in biology and vector capacity of this species.
Assuntos
Doenças do Cão/parasitologia , Ixodidae/classificação , Animais , Argentina , Sequência de Bases , Peso Corporal , Brasil , Cruzamentos Genéticos , DNA Mitocondrial/química , DNA Mitocondrial/genética , Cães , Comportamento Alimentar , Feminino , Fertilidade , Ixodidae/genética , Ixodidae/fisiologia , Masculino , Dados de Sequência Molecular , Filogenia , Reação em Cadeia da Polimerase/veterinária , RNA Ribossômico/química , RNA Ribossômico/genética , Coelhos , Alinhamento de Sequência , Infestações por Carrapato/parasitologiaRESUMO
Casos de demodicose bovina foram observados em um rebanho da raça Sindhi no período de dezembro 1989 a janeiro 1992. Ambas as formas, localizada e generalizada, foram diagnosticadas. Este é o primeiro relato da forma generalizada no Brasil. Nos dois primeiros anos, a demodicose foi diagnosticada somente em animais < 2 anos, enquanto que nos dois últimos anos, animais de todas as idades estavam positivos. A prevalência variou de 20,4 por cento (11/54) a 53,1 por cento (26/49) e 13,2 por cento (12/91) a 14,8 por cento (9/61) nos animais com menos e mais de 2 anos de idade, respectivamente. Os sinais clínicos variaram de pequenos nódulos a espessamento da pele com nódulos grandes e moles, nas formas localizada e generalizada, respectivamente. Os principais achados histopatológicos dos nódulos cutâneos na forma generalizada foram: acantose com hiperqueratose, adenite sebácea crônica, necrose muscular subcutânea e degeneração focal de células da camada basal da epiderme, além da presença de grande número de ácaros de localização intraluminal nos terços médio e inferior de folículos pilosos dilatados. Observou-se ainda perifoliculite crônica, caracterizada por infiltrado celular predominantemente linfoplasmocitário contendo ainda macrófagos e neutrófilos, que envolvia bulbos pilosos. O estado nutricional precário dos animais e o estresse provocado pela longa estiagem, provavelmente, contribuíram para aumentar a suscetibili-dade do rebanho à infestação pelos ácaros.