Mean corpuscular haemoglobin concentration as haematological marker to detect changes in red blood cells in sheep infected with Haemonchus contortus

Association of β-globin polymorphisms and tolerance to haemonchosis in ewes and lambs of different sheep breeds

Gastrointestinal nematodes (GIN), especially Haemonchus contortus, represent a significant challenge for sheep production. Given the global concern about GIN anthelmintic resistance, alternative control methods able to reduce the dependence on these drugs are highly advisable. Since previous studies have shown that sheep carrying the Hb-A allele of β-globin are more resistant to H. contortus, this study aimed to investigate the relationship between the different haplotypes (Hb-AA, Hb-AB and Hb-BB) and phenotypes in Santa Inês (SI), Texel (TX) and White Dorper (DO) breeds infected with H. contortus. Blood samples were collected from 180 ewes and 123 lambs of the three breeds for DNA extraction followed by qPCR using a hydrolysis probe to identify the β-globin haplotypes. Phenotypic data, including fecal egg count (FEC), packed cell volume (PCV), FAMACHA score and body condition score for ewes and lambs, as well as weight gain for lambs, were collected. The genotypic frequencies of β-globin for ewes and lambs were, respectively: 21.7% and 21.4% Hb-AA, 50% and 50% Hb-AB and 28.3% and 28.6% Hb-BB in SI; 0% and 0% Hb-AA, 18.6% and 9.4% Hb-AB and 81.4% and 90.6% Hb-BB in TX; and 0% and 0% Hb-AA, 13.1% and 0% Hb-AB and 86.9% and 100% Hb-BB in DO. In ewes, mean PCV differed (p<0.05) between the three haplotypes, with higher PCV in Hb-AA animals, followed by Hb-AB and Hb-BB. When considering each breed separately, SI Hb-AA ewes presented higher PCV (p<0.05), highlighting that even in a breed already considered resistant, animals with Hb-AA haplotype showed superior performance. Lambs with the Hb-AA haplotype exhibited a higher (p<0.05) mean PCV compared to those with Hb-AB and Hb-BB. The same pattern was found in SI when analyzing each breed separately. No significant association was found between β-globin haplotypes and FEC, FAMACHA score, body condition score, or weight gain. Nevertheless, given that anemia is the major clinical sign of haemonchosis, our findings on PCV reinforce that sheep carrying the Hb-A allele of β-globin are more tolerant to haemonchosis. This study may support the development of a valuable tool, targeting genetic selection for GIN control, reducing the dependence on anthelmintics and boosting sheep production worldwide.

Validation of targeted selective treatment (TST) methodology for gastrointestinal parasites of adult sheep in different physiological states

We aimed to validate a targeted selective treatment (TST) methodology for treating parasitic gastrointestinal infections in ewes in different physiological states using parasitological and hematological parameters. Forty ewes were monitored from December 2021 to June 2022 and evaluated during various physiological stages in their life cycle. Before starting the experiment, a fecal egg count (FEC) reduction test was performed to evaluate the efficacy of the anthelmintic (AH) treatment. Weekly assessments were performed based on the Famacha© (F) system and body condition score (BCS), and ewes were subjected to AH treatment when necessary, with their physiological states recorded. Ewes were treated when they presented F ≥ 3, BCS ≤ 2.0 (when F = 2), or submandibular edema. Parasitological, i.e., FEC, and hematological, i.e., hematocrit (Ht), parameters were evaluated monthly to determine the efficiency of the TST methodology. Comparisons between the mean Ht and FEC values in ewes subjected to AH treatment and untreated ewes were performed using analysis of variance, followed by Tukey's test. Spearman's correlation was performed to determine the correlation between the variables, i.e., F scores, BCS, Ht, and FEC. All tests were performed at a significance level of 5 %. During the experimental period, 1138 evaluations were performed. The main reason for AH treatment was F ≥ 3. Ewes in early pregnancy, lactation and late pregnancy received comparatively more AH treatments than the other physiological states. Ewes in late pregnancy and lactation exhibited lower mean Ht values (23.5 % and 22.9 %) and higher mean FEC values (3269 and 1426) compared with those in early pregnancy (30.2 % and 727 EPG). In addition, a statistically significant difference was observed in the Ht and FEC values of ewes that presented submandibular edema (P < 0.001) compared with those that did not exhibit submandibular edema. The genus Haemonchus sp. showed a 96.4 % prevalence in coprocultures. A positive correlation existed between F scores and FEC (r = 0.3819) and a negative correlation between F scores and Ht (r = -0.4728). Ewes that needed AH treatment had lower mean Ht values than ewes that did not need the treatment (19.2 % × 29.3 %; P < 0.001) and higher mean FEC values (8747 × 1163; P < 0.001), confirming that these ewes needed AH treatment. The TST methodology based on F scores, BCS, and submandibular edema could effectively identify individuals in the herd needing AH treatment, identifying 13 % additional cases requiring treatment than using only the F score criterion.

Estimates of genomic heritability and genome-wide association studies for blood parameters in Akkaraman sheep

The aim of this study was to estimate genomic heritability and the impact that genetic backgrounds have on blood parameters in Akkaraman sheep by conducting genome-wide association studies and regional heritability mapping analysis. Genomic heritability estimates for blood parameters ranged from 0.00 to 0.55, indicating that measured phenotypes have a low to moderate heritability. A total of 7 genome- and 13 chromosome-wide significant SNPs were associated with phenotypic changes in 15 blood parameters tested. Accordingly, SCN7A, SCN9A, MYADM-like, CCDC67, ITGA9, MGAT5, SLC19A1, AMPH, NTRK2, MSRA, SLC35F3, SIRT6, CREB3L3, and NAV3 genes as well as three undefined regions (LOC101117887, LOC106991526 and LOC105608461) were suggested as candidates. Most of the identified genes were involved in basic biological processes that are essential to immune system function and cellular growth; specific functions include cellular transport, histone deacetylation, cell differentiation, erythropoiesis, and endocytosis. The top significant SNP for HCT, MCH, and MCHC was found within a genomic region mainly populated by the MYADM-like gene family. This region was previously suggested to be under historical selection pressure in many sheep breeds from various parts of the world. These results have implications on animal breeding program studies due to the effect that the genetic background has on blood parameters, which underlying many productive and wellness related traits.

Hematological parameters of dogs for parasitism Dirofilaria immitis

The relationship between helminths and the host is built on a subtle molecular biological basis. Their pathogenic effect is characterized by the mechanical, toxic, inoculating effect on the host organism and the state of reactivity of his organism, immunological and allergic reorganization. It has been proved that helminths of the species Dirofilaria immitis are the most pathogenic nematodes of this genus because the localization of the imaginal stage of the parasite causes more complex pathogenesis of the invasion. The study aimed to establish changes in hematological parameters of dogs infected with D. immitis, considering the intensity of microfilariasis invasion. Studies have shown that the intensity of the invasion of up to 20 larvae/cm3 in the blood of dogs, significant changes in the number of erythrocytes, leukocytes, platelets, hemoglobin, and hematocrit and ESR were not found. The intensity of the invasion of 20–40 larvae/cm3 in infected dogs in the blood decreases the number of erythrocytes by 11.92 % (P < 0.05), the hemoglobin content by 16.33 % (P < 0.05), the hematocrit by 12.70% (P < 0.05) and the number of leukocytes increases by 15.17 % (P < 0.05). Indicators of the intensity of invasion of 40–60 larvae/cm3 in infected dogs showed more significant changes in the blood, which are characterized by a decrease in the number of erythrocytes by 25.54 % (P < 0.001), platelets by 34.03 % (P < 0.01), hemoglobin content by 30.86 % (P < 0.001), hematocrit by 20.56 % (P < 0.001) and an increase in the number of leukocytes by 32.75 % (P < 0.001) and ESR by 1.84 times 0.001). At indicators of the intensity of invasion of more than 60 larvae/cm3, in dogs significant (P < 0.001) decrease in the number of erythrocytes by 47.21 %, thrombocytes by 42.84 %, the content of hemoglobin by 42.27 %, the indicator of hematocrit by 41.57 % and an increase in the number of leukocytes by 44.98 % and ESR by 2.51 times. In the leukoform of dogs with increasing rates of microfilariae invasion, the number of eosinophils gradually increases to 62.38 % (P < 0.001), rod-shaped neutrophils to 27.48 % (P < 0.05), monocytes to 23.21 % (P < 0.01) and the number of lymphocytes is reduced to 45.45 % (P < 0.001). The data obtained indicate the importance of determining these indicators for heartworm disease, which complements the picture of clinical examination of animals and will allow more effective treatment of dogs in this invasion.