Original article – The Horse – written by Erica Larson, July 25, 2017
Transporting horses is stressful, particularly so for the senior horse, who may experience a compromised immune response, elevated stress hormones, and decreased body weight. Weakened immune responses as a result of transporting the senior horse may explain the frequency of respiratory illnesses in feedlots etc. These findings are yet another reason why senior horses should not be transported for the “humane end of life option” of slaughter.
“Researchers have long known that transportation can be stressful for horses—not only for their minds but also for their bodies. Still, scientists haven’t yet zeroed in on all the ways travel impacts horses’ body systems. They have proven that transport negatively impacts the immune function of other species, including cattle and swine, but little is known about the horse, and there’s no work investigating the impact on senior horses.
…the team hypothesized that, following short-distance transportation:
- Stress hormone (cortisol) levels would increase;
- Cell-mediated immune responses (which protect the body against intracellular organisms, such as viruses, using special white blood cells called T-cells; the T-cells recognize when a cell has been infected by a pathogen and act to eliminate it before the pathogen can replicate) would decrease; and
- Inflammatory cytokine production would increase.
The team used 16 senior horses with an average age of 25 years. They collected baseline blood samples and evaluated clinical parameters a week before a 1.5-hour trip. They gathered the same samples and data 15 minutes before the trip, 15 minutes after, and on Days 3, 7, 14, and 21 after transport.
Some of the team’s key findings included:
- Horses had decreased INF-γ (interferon-gamma, an inflammatory mediator produced by lymphocytes) production starting 15 minutes after travel and through Day 21;
- After transport, lymphocyte gene expression showed reduced INF-γ, TNF-α (tumor necrosis factor alpha, a cytokine involved in mediating systemic inflammation), and IL-10 (interleukin-10, another anti-inflammatory cytokine) levels;
- Cortisol levels were increased 15 minutes after travel;
- There were no differences in whole blood gene expression before and after transportation; and
- Horses’ body weights decreased on Day 3 post-transport.”
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