Host innate immune responses and microbiome profile of neonatal calves challenged with Cryptosporidium parvum and the effect of bovine colostrum supplementation.

Introduction: Calves are highly susceptible to gastrointestinal infection with Cryptosporidium parvum (C. parvum), which can result in watery diarrhea and eventually death or impaired development. With little to no effective therapeutics, understanding the host's microbiota and pathogen interaction at the mucosal immune system has been critical to identify and test novel control strategies. Methods: Herein, we used an experimental model of C. parvum challenge in neonatal calves to describe the clinical signs and histological and proteomic profiling of the mucosal innate immunity and microbiota shifts by metagenomics in the ileum and colon during cryptosporidiosis. Also, we investigated the impact of supplemental colostrum feeding on C. parvum infection. Results: We showed that C. parvum challenged calves experienced clinical signs including pyrexia and diarrhea 5 days post challenge. These calves showed ulcerative neutrophil ileitis with a proteomic signature driven by inflammatory effectors, including reactive oxygen species and myeloperoxidases. Colitis was also noticed with an aggravated mucin barrier depletion and incompletely filled goblet cells. The C. parvum challenged calves also displayed a pronounced dysbiosis with a high prevalence of Clostridium species (spp.) and number of exotoxins, adherence factors, and secretion systems related to Clostridium spp. and other enteropathogens, including Campylobacter spp., Escherichia sp., Shigella spp., and Listeria spp. Daily supplementation with a high-quality bovine colostrum product mitigated some of the clinical signs and modulated the gut immune response and concomitant microbiota to a pattern more similar to that of healthy unchallenged calves. Discussion: C. parvum infection in neonatal calves provoked severe diarrheic neutrophilic enterocolitis, perhaps augmented due to the lack of fully developed innate gut defenses. Colostrum supplementation showed limited effect mitigating diarrhea but demonstrated some clinical alleviation and specific modulatory influence on host gut immune responses and concomitant microbiota.

Evaluating the effectiveness of a single application of 7% iodine tincture umbilical dip as a prevention of infection of the external umbilical structures in dairy calves.

The objective of this randomized clinical trial was to evaluate the effectiveness of a single application of 7% iodine tincture-based umbilical dip for preventing infection of the external umbilical structures in dairy calves. Five dairy farms in southern Ontario were visited twice weekly from September 2020 through June 2021. Female (n = 244) and male (n = 40) Holstein calves were randomly assigned at birth to receive either a 7% iodine tincture-based umbilical dip (n = 140) or no treatment (n = 144). Calves in the 7% iodine tincture umbilical dip group had the product administered once by the producer shortly after birth. For each newborn calf, the experimental group, calving difficulty, volume and timing of colostrum administration, time of birth, calving pen cleanliness, and the dam ID were recorded. Calf body weight was recorded during the first visit after birth, and a blood sample was collected for measurement of serum IgG concentration. Calves were health scored twice weekly from enrollment until approximately 30 d of age for assessment of external umbilical infection, joint inflammation, respiratory disease, and diarrhea. The primary outcome of the study was external umbilical infection, which was defined as an enlarged umbilicus with pain, heat, or a malodorous discharge. Calves were also weighed at 30 and 60 d to determine average daily gain. Serum IgG concentration and birth weight did not differ significantly between groups. Twenty-nine calves (20%) in the umbilical dip group developed an external umbilical infections, compared with 31 calves (22%) in the control group. A mixed logistic regression model, accounting for farm as a random effect, showed no effect of treatment on the incidence of an external umbilical infection. However, for every additional hour that calves received colostrum after birth, the odds of developing an external umbilical infection increased during the first month of life (odds ratio = 1.15; 95% confidence interval: 1.04-1.26). Additionally, treatment had no effect on respiratory disease, joint inflammation, diarrhea, average daily gain, or mortality, compared with the untreated control. These findings suggest that administering a single application of 7% iodine tincture dip to the umbilicus around the time of birth may not be effective for preventing external umbilical infections. Farm-level management factors, including colostrum management, appear to have more influence on risk of this disease.

Acquired multiple acyl-CoA dehydrogenase deficiency and marked selenium deficiency causing severe rhabdomyolysis in a horse.

This report describes a case of severe rhabdomyolysis in a pregnant mare associated with histopathologic and biochemical features of both selenium deficiency and acquired multiple acyl-CoA dehydrogenase deficiency (MADD) due to seasonal pasture myopathy (SPM). This case highlights the importance of assessing plasma selenium levels in horses with clinical signs of pasture myopathy as this deficiency may be a contributing or exacerbating factor.

Déficience multiple acquise de déshydrogénase acyl-CoA et carence en sélénium marquée causant une rhabdomyolyse grave chez un cheval. Ce rapport décrit le cas d'une rhabdomyolyse grave chez une jument gravide associée à des caractéristiques histopathologiques et biochimiques de la carence en sélénium et d'une carence multiple acquise de déhydrogénase acyl-CoA (MADD) causées par la myopathie saisonnière des pâturages (SPM). Ce cas souligne l'importance d'évaluer les niveaux de sélénium dans le plasma des chevaux manifestant des signes cliniques de myopathie du pâturage car cette carence peut être un facteur contributif ou aggravant.(Traduit par Isabelle Vallières).