Weanlings and the chill of winter: Study explores respiratory disease risk


Horse owners often worry about the wellbeing of their weaned foals, especially when the chill of winter bites as they start to make their own way in the world.

Researchers in Finland have conducted what they believe to be the first study on respiratory disease in weanlings living in a cold climate.

They found that a young age was the most important factor associated with the occurrence of clinical respiratory disease.

The study team found there was no difference in the occurrence of clinical respiratory disease in weanlings housed in stables when compared to those in the loose housing systems favoured by many for raising weanlings in Finland.

Reija Junkkari and her colleagues, writing in the journal Acta Veterinaria Scandinavica, had set out to compare conventional stabling with unheated loose housing on the respiratory health of weaned foals in cold winter conditions.

Newly weaned horses in Finland are often moved to unheated loose housing systems in which the youngsters have free access to a paddock and a shelter. This practice is considered to be good for the development of young horses.

Daily temperatures can stay below minus 20 degrees Celsius in Finland for several consecutive weeks during winter.

The study involved 60 weanlings raised among 11 different rearing farms in Finland. Thirty-six of them were kept in unheated loose housing systems and 24 were in stables. The study animals comprised Finnhorses and Standardbreds.

The humidity or air particulate concentration were not measured as part of the study, but air quality was estimated to be good in all stables and sleeping halls.

The animals were clinically examined twice, 58 days apart, in cold winter conditions, and samples were taken for the testing of several things, including levels of plamsa fibrinogen, which is considered a biomarker of respiratory disease.

The average age of the weanlings was 6.2 months at the first examination.

The odds of clinical respiratory disease were lower in the older foals, the study team found.

Plasma fibrinogen concentrations were higher in cramped sleeping halls. They were also found to be higher in loose sleeping halls that were insulated, compared to those that lived in systems with non-insulated sleeping halls or in the stables. This surprised the researchers.

Plasma fibrinogen concentrations at the second examination were lower for animals with a body condition score above 3.

Standardbreds kept in loose housing systems had a lower body condition score than Finnhorses or Standardbreds kept in stables at both examinations.

“Standardbred weanlings seem to have a higher energy demand in a cold environment compared to that of their Finnhorse counterparts,” they said.

Haemoglobin levels were lower in weanlings in loose housing systems compared to their counterparts at the first examination. Finnhorses had higher white blood cell count than Standardbreds at the first and second examinations.

No differences were detected in relation to the breed or sex of the weanling in terms of clinical disease. Bedding material or other differences in conditions did not affect the risk of clinical disease in cold loose housing, either.

“Keeping weanling horses in cold loose housing systems does not seem to increase the occurrence of respiratory disease, but special attention should be focused on ventilation, air quality and feeding practices,” the researchers concluded.

The data suggested it might be better to keep Standardbred foals born late in the season in a stable over the Finnish winter, they added.

They said a full evaluation of the influence of certain environmental factors would require a study with more horses being kept in more precisely defined conditions.

“It would also be worthwhile to make a nationwide survey for weanling owners to evaluate the occurrence of respiratory disease in different management systems because veterinarians only detect cases that require medical attention.”

Further studies with more weanlings and farms were warranted to define the optimal loose housing conditions for weanlings in a cold climate, they said.

The researchers comprised Junkkari, Heli Simojoki, Satu Sankari, Riitta-Mari Tulamo and Anna Mykkänen, all from the University of Helsinki; Minna-Liisa Heiskanen from the Equine Information Centre; and Sinikka Pelkonen, from the Finnish Food Safety Authority.

A comparison of unheated loose housing with stables on the respiratory health of weaned-foals in cold winter conditions: an observational field-study
Reija Junkkari, Heli Simojoki, Minna-Liisa Heiskanen, Sinikka Pelkonen, Satu Sankari, Riitta-Mari Tulamo and Anna Mykkänen
Acta Veterinaria Scandinavica 2017 59:73 https://doi.org/10.1186/s13028-017-0339-3

The study, published under a Creative Commons License, can he read here

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