Exercise and pregnant mares

In humans, moderate exercise in pregnancy seems to do no harm and may help limit excessive weight gain and maintain fitness for the birth. What about horses? Many pregnant mares are ridden and subject to moderate training up to the later stages of pregnancy.

A research team from the University of Maine and the Equine Science Center, Rutgers University, New Jersey compared the response of pregnant and non-pregnant mares to a graded exercise test.

Six unfit standardbred mares were assessed when nine months pregnant and again eight months later after weaning. The exercise test was carried out on a treadmill inclined at 6%. The speed increased in steps of one minute each at 4m/s, 6m/s and 7m/s.

At each stage of the graduated exercise test, mares had lower heart rates when pregnant than after weaning. Plasma lactate concentrations rose less in response to exercise when mares were pregnant than when they were not. The researchers speculate that this might be due to greater cardiovascular efficiency during pregnancy.

Resting plasma cortisol levels were lower during pregnancy than when the mares were not pregnant.

When exercised, pregnant mares showed no increase in cortisol levels. In contrast, when they were not in-foal, the mares showed a normal increase in plasma cortisol during and after the exercise test.

Neither did exercise have an effect on foetal heart rate. This suggests that the unborn foal is not stressed by the mare undertaking moderate exercise.

The researchers conclude: “these data suggest that pregnant mares benefit from greater cardiovascular efficiency during pregnancy. They should be able to perform limited moderate exercise without any major deleterious effects on their unborn foals or themselves during late gestation.”


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Tick-borne disease in Danish horses

Tick-borne infections are common in Danish horses. A survey published in Acta Veterinaria Scandinavica showed that many Danish horses carry antibodies to Borrelia burgdorferi sensu lato (the group of Borrelia species known to cause Lyme disease) and Anaplasma phagocytophilium (the cause of equine granulocytic anaplasmosis).

The study, overseen by Dr Anders M Bojesen of the Department of Veterinary Disease Biology, Faculty of Life Sciences, University of Copenhagen, Denmark aimed to evaluate the seroprevalence of B. burgdorferi s. l. and A. phagocytophilium in Danish horses.

Overall, 29.0% horses were seropositive for B. burgdorferi s. l. and 22.3% were seropositive for A. phagocytophilium. This was a higher proportion than had been found in previous studies in neighbouring countries.

There was no significant correlation between risk factors investigated, including breed, gender, age, use and housing and the occurrence of antibodies against B. burgdorferi s. l.

However the researchers did find that older horses were more likely to have been infected with A. phagocytophilium. Compared with horses aged between 1-4 years old, those aged 11-20 years were 2.3 times more likely to be seropositive for A. phagocytophilium, and horses over 21 years old were 3.3 times more likely to be seropositive.

Horses seropositive for B. burgdorferi s. l. were likely to be seropositive for A. phagocytophilium and vice versa.

The researchers conclude “these findings warrant further attention to these infections in horses particularly with regard to improved means for detection of active infections, which may contribute to a better understanding of these diseases and their impact on horse behaviour and welfare.”

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New equine respiratory condition described

Danish Researchers have identified a new cause of respiratory disease in horses. They found the bacterium Stenotrophomonas maltophilia in samples collected from horses with chronic lower airway disease.

Stenotrophomonas maltophilia, a Gram-negative bacterium, has been found increasingly in human medicine, especially in patients with impaired immune systems. Until recently the organism has been recorded only rarely in animals.

In a paper to be published in The Veterinary Journal, Lotte Winther, a PhD student in the Department of Large Animal Sciences at the University of Copenhagen, and colleagues present data from seven horses with respiratory disease associated with S. maltophilia infection.

All cases had a history of chronic coughing. Endoscopic examination revealed copious mucopurulent exudate in the lower trachea. Culture of the tracheal exudate produced grey, slow-growing colonies, which were identified as S. maltophilia by both culture and DNA testing.

Many antibiotics commonly used to treat equine respiratory infections were not effective against S. maltophilia.

The findings suggest that S. maltophilia can act as a respiratory pathogen. The researchers advise that the organism be included in the differential diagnosis of horses with respiratory disease associated with copious mucopurulent exudate.

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TEST TO PREVENT UNNECESSARY FOAL DEATHS LAUNCHED

A new diagnostic test, which gives breeders the ability to eradicate Foal Immunodeficiency Syndrome, was launched on 1 February by UK scientists.

Foal Immunodeficiency Syndrome (FIS), a genetic disorder which is known to affect Fell and Dales ponies, causes foals to become anaemic and prone to opportunistic infections. Sadly, any foal born with the syndrome will not survive.

The DNA test, which costs £40, will not only identify foals which have the fatal condition but will highlight adult ponies who are carriers of the genetic trait which causes the syndrome. Affected foals will be prevented by avoiding breeding a carrier mare with a carrier stallion.

Owners and breeders who wish to find out the genetic status of their ponies can arrange for a simple pulled mane or tail hair sample to be taken by a vet and submitted to the Animal Health Trust. The Fell Pony or Dales Pony Societies will supply sample bags for submission on request.

Dr. June Swinburne of the AHT, who led the research team, said: “The DNA test gives owners and breeders the power to overcome this devastating illness. It enables them to make informed decisions about which ponies to breed. We have already had samples submitted by HM The Queen from her own breeding stock of Fell ponies. I’d urge any breeders of Fell or Dales ponies to submit samples in order to arm themselves with the facts they need to prevent the birth of affected foals and thereby avoid this distressing condition.”

For more information on testing, owners should contact the Fell or Dales Pony Societies.
Alternatively visit the AHT website http://www.aht.org.uk/genetics_fis.html or email FIStesting@aht.org.uk