RESPIRATORY ranks second only to orthopaedic disease as a cause of poor performance in athletes (racehorses at least). If they can’t breathe properly, how can we expect them to run and jump at speed? Typically, vets divide respiratory disease conditions along geographical lines – upper versus lower regions of the respiratory tract (URT and LRT respectively). The former comprises nostrils, nasal passages, pharynx (throat) and larynx (voice box); the latter trachea (windpipe) to lungs. I’m going to focus on the URT here, but firstly a short reminder about the importance of good LRT function.

Respiratory infections have been much in the news during recent pandemic times and it might go without saying here that ‘there’s nothing better for horses, as for ourselves, but to spend time outside – in the fresh air’.

When we keep them cooped up in low-roofed, stuffy stables feeding on mouldy food, horses perform poorly at fast paces. They are often reported to ‘scope poorly’ – by which is meant that a vet can see pus or blood in the windpipe when they go looking. But disorders of the URT (especially pharynx and larynx) do feature large in the life of racehorses.

A show jumping stallion ‘making a noise’ may be more of a problem for his stud value than his jumping. A racehorse (or top-flight eventer) on the other hand, needs every bit of oxygen he can inhale when the pressure is on to get over the finish line. Horses have to breathe through their nose, never their mouth; ideally, lips should stay closed to create a seal. An argument for bitless bridles perhaps, until one considers that some of the fastest horses loll their tongue out while winning!

Horses have to inhale/exhale once for every gallop stride and the pipe-work needs to be in perfect working order, dilated wide and free from obstruction. If not, the horse struggles in his breathing and falters in his stride. It’s often the winning or losing of a race, particularly over longer distances or heavy going – stamina-sapping conditions. Sprinters, à la Usain Bolt on a perfectly level and smooth track, might get over the line almost before their body knows it lacks oxygen. But stayers fall in a heap going to the last fence or furlong as the case may be. All jockeys have experienced a faltering horse, hopes dashed of making it home in front: they know the sinking feeling of a horse dying beneath them.

The most common problem with the pharynx relates to upward (or dorsal) displacement of the soft palate (DDSP) – unhelpful to the horse at a time other than when swallowing. These horses ‘gurgle’ as they displace their palate from its expected position down against the tongue and wrapped around the larynx. Horses can’t breathe (as we might) through their mouth; the palate flaps like a loosened sail obstructing the passage of air; and the horse loses that intimate connection between breaths and strides. And so the race passes them by.

Over the years treatments have ranged from the cheap and cheerful (notably a tongue-tie), to expensive surgical procedures such as the ‘tie-forward’. And several in between – cutting neck muscles, injecting, trimming and stiffening flaccid tissues. Whenever there are multiple possible treatments, a general principle applies – we haven’t got all the answers!

  • In some horses, it comes down to immaturity and lack of fitness – more training tightens the tissues of the throat and these perform better.
  • If LRT disease (such as lung infection) is present, it causes air hunger – this must be fixed first.
  • Nasal strips placed on the nose – do these improve airflow?
  • Glycerine syringed into the mouth might make palate and tongue stick more to each other.
  • A crossed noseband may encourage the horse to keep his mouth closed and lips apposed.
  • A tongue-tie may serve to stop the tongue from pushing back and up against the soft palate causing it to displace at the wrong moment.
  • Cutting specified neck muscles prevents the larynx from moving backwards thereby losing its close connection with the soft palate.
  • A ‘tie-forward’ moves the larynx to lie up, more cosily against the soft palate.
  • Cauterising (burning) the soft-palate from nasal or oral sides (that is from above or below, using a laser or hot irons) may stiffen it so that it less likely to flap free at the wrong moment.
  • Injecting selected agents into the palate may get it to function better, staying in place unless a swallow is in order (i.e., when eating or drinking).

    • The most common problem with the larynx is left hemiplegia. The cartilages of one (almost always the left) side of the voice-box don’t move properly: they should close inward during swallowing and open wide when galloping. Flapping of a cartilage causes the characteristic noise – hence ‘roarer’ and ‘whistler’ – listened for with great concentration by countless vets at pre-sales examinations.

    The cause is an inherited weakness in a nerve supplying the larynx, which some vets try to fix by diverting another nerve. Far more common has been the procedure named for a once famous veterinary surgeon – the Hobday – designed to tighten the tissues of the larynx so that they vibrate less. Some vets now feel that this is more useful as a cosmetic procedure – removing annoying noise in the showjumper, for example.

    The surgery most commonly chosen for a racehorse needing a more permanent fix is the ‘tie-back’. Here, the flapping cartilage is held sideward by a suitably placed suture. The horse should now breathe freely when galloping. An unintended consequence may be the inhaling of food into the windpipe when eating, something not to be scoffed at.

    In the control of respiratory disease, particularly of the URT, physical methods have their place, absolutely. Fixing flaccid, flabby pieces in their proper place can really make the difference. But fitness, maturity and good respiratory hygiene really matter too: time outdoors when possible, keeping it fresh indoors; vaccinate and keep infection at bay.

    Next week: Sir Mark Prescott special