WHAT’S NEW in the veterinary world?
In his latest research round-up, Peter Green MRCVS looks at ways of weaning and potential treatments for joint problems and laminitis
MISSING MUM
SUDDEN, abrupt weaning is not always the best way to separate a foal from his dam, yet this method is widely employed — especially on commercial studs where large groups of foals can be weaned together.
We know that being with other weanlings reduces the stress, but researchers in Germany have discovered that colts and fillies differ in their responses.
At the Brandenburg
Stud, 11 male and 11 female warmblood foals were suddenly separated from their dams at about six months old, but were kept together in their foal peer groups. Both the fillies and the colts showed signs typical of acute stress in their behaviour, their heart rates and their salivary cortisol levels. These signs were not identical, however, in the two sexes.
The fillies lost more weight than the colts, but the colts spent more time whinnying and shouting for their mums. The colts defaecated more frequently, but the fillies had overall higher cortisol levels in the week following weaning.
The scientists concluded that both sexes found sudden weaning equally stressful, but showed the stress in different ways. This is a crucial finding, because it confirms that in both behaviour and physiology there are inherent differences between male and female horses.
Because these youngsters were only six months old and had been together since birth, the discrepancies cannot be explained by differences in experience, training, handling or hormones.
NEW SOLUTIONS?
WE have learnt a lot about many diseases in horses in the past 30 years, but there has been little progress in the treatment of some of them.
Joint disease and laminitis are good examples: we know far more about the progress of degenerative joint disease and the processes going on inside the joint, and we understand far better the mechanical and vascular problems that occur in a laminitic hoof. However, there has been little change in effective treatments.
Non-steroidal antiinflammatory drugs (NSAIDs) like phenylbutazone (bute) and its relatives remain the bedrock therapy for both conditions, especially when they have become chronic. Certainly, we have developed injections to put into joints and our approach to the trimming and shoeing of laminitic hooves has improved, but these have not really offered a genuine long-term therapy.
In unrelated research papers, vets have suggested that two completely novel treatments be considered.
Swiss vets looked at metallic gold as a possible therapy for joint disease. Gold is already known to have genuine anti-inflammatory properties, but how can these be harnessed clinically?
The vets took microscopic gold particles mixed with artificial joint fluid and injected them into the knees of healthy horses. The experiment was not designed to test whether gold was effective as a treatment, but whether it was safe. The size of the particles is critical: too small and they are swallowed up by scavenging white cells; too big and they cause irritation in the joint. The vets found that the micro-implants they used had no harmful effect on the healthy joints and will now test their therapeutic effect.
Vets in Colombia have proposed that platelet-rich plasma (PRP) may offer an effective treatment for laminitis. PRP is simply blood serum with an elevated concentration of blood platelets. This is already known to have beneficial properties because it contains high levels of important naturally occurring antiinflammatory compounds, such as growth factors, cytokines, chemokines and other substances that can control the damaging effects of chemicals known to be circulating when horses have laminitis.
PRP also contains polypeptides, which could have a positive effect on the course of this disease. In fact, the vets argue that the benefits of PRP that have been established in other human and animal diseases could also be applied to laminitis.
FURTHER READING
Weaning: Journal of Veterinary Behaviour 23, 19-24
Gold: Journal of Equine Veterinary Science 60, 59-66
PRP: Journal of Equine Veterinary Science 61, 46-57