Zinc Sulphate Turbidity as a Screening Test of Passive Transfer of Immunity in Newborn Foals

Background: Passive immunity acquired by colostrum ingestion is essential to prevent neonatal infections. Failure of passive transfer (FPT) of maternal immunity occurs in foals that fail to absorb enough immunoglobulins within 24 h after birth. Foals with FPT are at increased risk of infections and death. Serum samples from neonatal foals might be examined for FPT using the zinc sulphate turbidity (ZST) test. The aim of this study was to investigate the accuracy of the ZST test, performed at two different times after first suckling (12 and 18 h), to detect FPT in newborn foals. The effect of temperature on the turbidity intensity resulting from the ZST reaction was also investigated.Materials, Methods & Results: Blood samples were collected from 112 newborn foals at 12 h after the first colostrum intake. In 36 foals, additional serum samples were collected at 18 h after first colostrum intake. The serum samples were tested with the ZST test and, later, in the laboratory setting, the ZST test was repeated. The IgG levels were measured by single radial immunodiffusion (SRID), which was used as the reference method. The standard solution used for the interpretation of results had a turbidity corresponding to approximately 800 mg/dL of immunoglobulins (IgG). The mean IgG concentration measured at 12 and 18 h after the first colostrum intake was analyzed using the t-test for paired samples. Values of absorbance of ZST test under different temperatures were analyzed using a one-way analysis of variance, and means were compared using the Tukey test. The relationship between the temperature of the solution and absorbance was determined using the Pearson’s correlation coefficient. Based on SRID results, 12 foals (10.7%) had serum IgG concentration 0.05) between 12 h (943.9 ± 508.6 mg/dL) and 18 h (975.9 ± 525.6 mg/dL) after the first colostrum intake. The sensitivity values were 76.3% and 71.0% (P > 0.05) for tests performed at farm and laboratory, respectively. The specificity was higher (P < 0.05) for ZST tests performed at laboratory (94.6%) than at farms (73.0%). Twenty-nine of the 38 foals (76.3%) with IgG < 800 mg/dL were correctly detected using the ZST test at farms. There was a strong correlation (r = 0.92; P < 0.0001) between the temperature of the solution test and the degree of turbidity. The absorbance after the reaction of serum with zinc sulphate was similar between the temperatures of 30, 34 and 37ºC, which had higher values than 20 and 25ºC.Discussion: The ZST test can be performed at 12 h after the first suckling. The lower specificity of tests run at farms compared to laboratory resulted in more foals with false positive diagnosis. The main cause of false positives at farms was probably the low temperature of the zinc sulphate solution at the time of testing, delaying the reaction and underestimating the IgG concentration. This assumption was reinforced by the increased specificity observed when the test was repeated with the same serum samples under controlled temperature of a laboratory. Additionally, the positive correlation observed between the temperature and degree of turbidity confirms that the reaction is temperature dependent. In the Southern hemisphere, most Thoroughbred foals are born during winter, when room temperature is far below the ideal temperature for good performance of the ZST test. Therefore, the number of false positives will likely be reduced if tests are performed at the farms under adequate temperature of solution (between 30 and 37ºC). This will reduce the number of foals receiving unnecessary treatment

The importance of vertical transmission of Neospora sp. in naturally infected horses

AbstractNeospora spp. is a intracellular protozoan phylogenetically closely related to Toxoplasma gondii and Sarcocystis neurona, and it can infect horses leading to the development of reproductive or neurological diseases. We determined the presence of antibodies to Neospora sp. in mares at their parturition time and determine the frequency of vertical transmission in healthy foals to verify the importance of transplacental transmission. The samples were analyzed by indirect immunofluorescence antibody test, showing that seroprevalence in mares is higher than in foals and seropositive mares are likely to transmit the neosporosis to their offspring. This shows that endogenous challenge occurs in horses, and it suggests that this protozoan can be disseminated by means of transplacental transmission in horse species

Anticorpos anti-Neospora spp. em amostras sorológicas de potros pré-colostrais pela técnica de imunofluorescência indireta Antibodies anti-Neospora spp. in sample sera of presuckle foals by indirect fluorescent antibody test

Buscou-se detectar a frequência de anticorpos anti-Neospora spp. em amostras de potros pré-colostrais, bem como estabelecer a melhor diluição do soro sanguíneo para ser utilizado na imunofluorescência indireta. Foram analisadas 203 amostras sorológicas de potros pré-colostrais, pela reação de imunofluorescência indireta em diferentes titulações. As titulações 16 e 50 apresentaram 25,1% e 9,9% de potros pré-colostrais positivos, respectivamente. Dessa forma, em amostras de soro de animais desprovidos de colostro, pode-se considerar a titulação 16 mais apropriada para detectar a ocorrência de infecção pelo protozoário e assim da transmissão transplacentária pelo Neospora spp. em equinos.<br>The objective of this study was to detect the frequency of antibodies against Neospora spp. in samples of presuckle foal, as weel as determine the best dilution of serum to be used in indirect fluorescent antibody test. We analyzed serum samples from 203 presuckle foals, by indirect fluorescent antibody test in different titrations. The titrations of 16 and 50 showed 25.1% and 9.9% of presuckle foals positive, respectively. Thus, in serum samples from presuckle foals the titration 16 can be considered more appropriate to detect the occurrence of infection by the protozoan and therefore the transplacental transmission of Neospora spp. in horses

Claudicação em cavalos Crioulos atletas Lameness in athletic Criollo horses

O objetivo deste trabalho foi identificar as principais causas de claudicação em cavalos Crioulos em treinamento para a prova do Freio de Ouro e competições de rédeas. Foram avaliados os registros clínicos de 201 cavalos Crioulos, 5,6 2,1 anos de idade, submetidos a exame físico devido à presença de claudicação ou histórico de baixo rendimento atlético entre os anos de 2002 a 2009. A claudicação foi localizada nos membros torácicos e pélvicos em 47,1% (n=105) e 52,9% (n=118), respectivamente. Nos machos, houve uma predominância de claudicação nos membros pélvicos (60,0%) e nas fêmeas nos membros torácicos (57,1%). Nos membros torácicos, 17,1% (18/105) das alterações foram diagnosticadas proximais à articulação metacarpofalangeana, 14,3% (15/105) na articulação metacarpofalangeana e 68,6% (72/105) estavam localizadas distais à articulação metacarpofalangeana. Nos membros pélvicos, 78,8% (93/118) apresentaram a origem da dor na região do tarso, 17,8% (21/118) proximal ao tarso e 3,4% (4/118) distal ao tarso. As articulações interfalangeanas distais e intertarsiana distal/tarsometatarsiana são importantes fontes de dor e inflamação e estiveram mais frequentemente envolvidas em claudicações de membro torácico e pélvico, respectivamente. Os cavalos Crioulos apresentam problemas de claudicação semelhantes aos descritos em outras raças que participam de provas de rodeio.<br>This study aimed to identify the source of lameness in Criollo horses that are competing in the most important discipline for this breed in Southern Brazil and also in reining competitions. Clinical records of adult Criollo horses (n=201), 5.6 2.1 years of age, that underwent lameness examination due to history of poor performance or lameness between 2002/2009 were analyzed. Lameness was diagnosed in the front limbs in 47.1% (n=105) and in the hind limbs 52.9% of the cases (n=118). In males 60.0% of the lameness cases were located in the hind limbs. In females 57.1% of the lameness cases were located in the front limbs. In the front limbs (47.1%, n=105/201), problems proximal to the fetlock were diagnosed in 17.1% (18/105). Fetlock problems were diagnosed in 14.3% (15/105) and lesions located distal to the fetlock level were seen in 68.6% (72/105) of the lameness cases diagnosed in the front limbs. In the hind limbs, problems located proximal to the tarsus were seen in 17.8% (21/118), 78.8% (93/118) in the tarsus and 3.4% (4/118) of the cases were seen distal to the tarsus. The distal interfalangeal joint in the front limbs and the distal tarsal joints in the hind limbs were the two most important sources of lameness. Criollo horses presented similar lameness problems as described in other show horses (reining, cutting and roping). This is the first lameness study done in Criollo horses and it will help to better understand the musculoskeletal diseases affecting this breed