Hematological profile of healthy Thoroughbred foals from birth to one month of age in Trinidad, West Indies.

OBJECTIVE: This study aimed to develop a sound database for the hematological reference intervals of thoroughbred foals in Trinidad, West Indies from birth to 1 month of age. ANIMALS: 89 foals. METHODS: Whole blood samples were taken from 89 foals throughout Trinidad at approximately 1 day, 1 week, and 1 month of age. These foals were examined to be classified as healthy or free from disease. Complete blood count (CBC), microscopic analysis of blood smears, and conventional PCR for Theileria equi and Babesia caballi were performed. RESULTS: Of the 89 foals, 67 were deemed healthy and suitable for establishing reference intervals. Foals in this study had lower mean hemoglobin and hematocrit values for all 3 times of sampling when compared to their North American counterparts. Age had a significant effect on hemoglobin, hematocrit, white blood cell (WBC), neutrophil, and platelet counts of the foals from birth to 1 month of age. CLINICAL RELEVANCE: Variations in reference intervals can occur due to differences in demographic, physiological, and environmental factors such as age, gender, breed, and geographical location. Given the changes in the hematological values over time, this study provides clinicians with valuable information that can be used to monitor the health status of newborn foals and detect disease conditions.

Phylogenetic analysis of Theileria equi and Babesia caballi sequences from thoroughbred mares and foals in Trinidad.

The agents of equine piroplasmosis, Theileria equi and Babesia caballi, are endemic in Trinidad, West Indies. While transmission is mainly by ixodid ticks, transplacental transmission of T. equi has also been reported. This disease has contributed to foetal losses as well as morbidity and mortality of neonatal foals and adult horses. Previous 18S rRNA-based phylogenetic studies indicated a noticeable degree of variation within and among B. caballi and T. equi isolates from different geographical regions. The objective of this study was to evaluate the diversity of T. equi and B. caballi obtained from horses in Trinidad by amplifying a region of the 18S rRNA gene. The phylogenetic trees for T. equi sequences obtained from horses in 2006 and 2011-2013 revealed that Trinidad sequences were of genotype A. Additionally, all of the B. caballi sequences from Trinidad were grouped together with other B. caballi sequences of genotype A. However, T. equi sequences from horses in Saint Kitts and Nevis clustered with sequences of genotype C. This study also identified two genotypes of T. equi in the equine population of Brazil. All of the T. equi and B. caballi sequences obtained from horses in Trinidad belong to genotype A and were similar to T. equi and B. caballi sequences of the same genotype that were submitted to GenBank™ databases. Countries in close proximity to Trinidad have T. equi sequences belonging to genotype C; therefore, movement of horses between these countries can introduce a new genotype of T. equi into the equid population of Trinidad.

Prospective study investigating transplacental transmission of equine piroplasmosis in thoroughbred foals in Trinidad.

Equine piroplasmosis caused by Theileria equi and Babesia caballi is endemic in Trinidad and Tobago. Transmission occurs by ticks of the family Ixodidae. T. equi can also be transmitted transplacentally; however transplacental transmission of B. caballi is unknown. This study aims to investigate transplacental transmission of equine piroplasmosis from thoroughbred mares naturally infected via the tick vector. Whole blood and serum samples were collected from 117 mares in the fifth month of pregnancy. Blood samples were also collected from each of their foals (89 in total) within the first 36h of birth. Additionally, all foals were observed for clinical signs within 30days post - partum. All samples were examined microscopically for intra-erythrocytic piroplasms. Serum ELISA tests and PCR analysis on whole blood were performed to determine the presence of T. equi and B. caballi. Thirty-four (30.6%) mares and 14 (15.7%) of their foals were seropositive for T. equi. Twenty-seven (24.3%) mares were positive for T. equi by conventional (c) PCR. Real time (q) PCR analysis based on the ema - 1 gene revealed that seven (8%) foals were positive for T. equi. Eighty-nine (76.1%) mares and 38 (42.7%) foals were seropositive for B. caballi. Four (3.4%) mares were positive for B. caballi by cPCR. Three out of the four cPCR positive mares either had resorptions, or stillbirths for that pregnancy. From this study, there is strong evidence that transplacental transmission of B. caballi can occur leading to foetal losses. Six foals (7%) were positive for B. caballi by qPCR. Of these six, four were born to B. caballi seropositive mares. In this study a foal born of a T. equi seropositive mare was 55.7 times more likely to be serologically positive for T. equi than a foal born to a T. equi seronegative mare. Similarly a foal born of a B. caballi seropositive mare was 39.4 times more likely to be serologically positive for B. caballi than a foal born to a mare that was serologically negative for B. caballi at the fifth month of pregnancy. This is as a result of the ingestion of colostrum containing antibodies to these pathogens. Mares should be screened during pregnancy and their foals closely monitored at parturition for evidence of equine piroplasmosis so that treatment can be implemented earlier for a better prognosis.

A case of transplacental transmission of Theileria equi in a foal in Trinidad.

Equine piroplasmosis due to Theileria equi and Babesia caballi is endemic in Trinidad. A case of equine piroplasmosis due to T. equi was diagnosed in a thoroughbred foal at 10h post-partum. A high parasitaemia (63%) of piroplasms was observed in a Wright-Giemsa(®) stained thin blood smear from the foal. In addition, the 18S rRNA gene for Babesia/Theileria was amplified from DNA extracted from the blood of the foal and the mare. Amplified products were subjected to a reverse line blot hybridization assay (RLB), which confirmed the presence of T. equi DNA in the foal. The mare was negative by RLB but was positive for T. equi using a nested PCR and sequence analysis. In areas where equine piroplasmosis is endemic, severe jaundice in a post-partum foal may be easily misdiagnosed as neonatal isoerythrolysis. Foals with post-partum jaundice should be screened for equine piroplasmosis, which may be confirmed using molecular methods if available.