Proceedings of a Workshop on - The Havemeyer Foundation

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Havemeyer Foundation Monograph Series No. 11 SALES: PROBLEMS IN DIAGNOSIS OF RLN – UK PERSPECTIVE D. R. Ellis, T. R. C. Greet † and J. G. Lane * Greenwood, Ellis & Partners, Reynolds House, 166 High Street, Newmarket, Suffolk, † Rossdale & Partners, Beaufort Cottage Equine Hospital, Cotton End Road, Exning, Newmarket, Suffolk CB8 7NN and * Department <strong>of</strong> Clinical Veterinary Science, University <strong>of</strong> Bristol, Langford House, Langford, Bristol, BS40 5DU, UK Tattersalls, Ltd Conditions <strong>of</strong> Sale re Wind Conditions in Thoroughbred Yearlings or Horses in Training: 1978–1983 A horse is returnable if it can be heard to make a characteristic abnormal inspiratory sound when exercised actively. 1984 As above but add and/or has laryngeal hemiplegia when examined with the endoscope. 1985 Makes a characteristic abnormal inspiratory sound AND has laryngeal hemiplegia (RLN). After the horse is sold the purchaser appoints a veterinary surgeon to listen when the horse is lunged and if it makes any abnormal inspiratory noise it is endoscoped. If it is found to have recurrent laryngeal neuropathy (RLN) the purchaser returns the horse to Tattersalls for adjudication by their panel. The panel has included the authors since 1984 with occasional alternates. Yearlings are returnable within 24 h <strong>of</strong> sale, and horses in training within 7 days. The panel examines the horse soon after its return, <strong>of</strong>ten later on the same day as the original test by the purchaser’s veterinary surgeon. Each member <strong>of</strong> the panel palpates the larynx for atrophy, cartilage symmetry and surgical scars. The larynx is also palpated immediately after exercise for fremitus and the right arytenoid depression test. These observations provide supportive evidence and with the exception <strong>of</strong> surgical scars would not be decisive. The yearling is then lunged on both reins at the canter which may be repeated on a particular rein but it is never lunged to exhaustion and the exercise lasts only a few minutes. The lunging ring is well designed with good acoustics and a fibresand surface. Horses in training are ridden at a fast canter uphill on a polytrack surface with members <strong>of</strong> the panel standing close to the end <strong>of</strong> the canter to hear the animal pass by. This exercise can be repeated if necessary. The horse is then allowed to settle down after the exercise before it is endoscoped. Originally the panel endoscoped horses before exercise but this policy was changed in order to mimic the examination by the purchaser’s veterinary surgeon and eliminate bias in the exercise test. The horse is scoped without a twitch, if possible, and only sedated if essential and with the agreement <strong>of</strong> the vendor and purchaser. The larynx and pharynx are examined via the right nostril in order to reduce the parallax effect for left sided RLN. During the examination the nostrils are blocked and deglutition is stimulated. The panel does not employ a slap test. Until recently each member examined the larynx via the same endoscope in sequence. A videoendoscope is now used but the examination is not recorded on tape Endoscopic criteria for RLN which mean the horse will be returnable include gross resting asymmetry <strong>of</strong> the rima glottidis, failure to achieve symmetric or full abduction and failure to maintain symmetric abduction during a complete inspiration, ie premature weakness. Each panelist forms his own view but sometimes members have discussed certain aspects such as the character <strong>of</strong> the inspiratory noise or the endoscopic findings. In most cases the decision was unanimous but in 11.5 % or 41 cases out <strong>of</strong> 356 between 1989 and 2002 majority decisions were reached. Problems with the system include incomplete examination by a purchaser’s veterinary surgeon and some veterinarians have a higher percentage <strong>of</strong> passes among those they return to the panel. Judgement <strong>of</strong> noise can be difficult in yearlings 39
Equine Recurrent Laryngeal Neuropathy TABLE 1: Summary <strong>of</strong> race records <strong>of</strong> yearlings returned for their wind under Tattersalls’ Condition <strong>of</strong> Sale and Control 1978–1984 1978-1983 27 returned for whistling/roaring only (52% did not run; 22% won; 2.8 average starts per horse) 1984 28 returned for whistling/roaring and/or RLN. (39.3% did not run; 39% won; 5.9 average starts per horse) 1978-1984 controls – the 2 sold before and the 2 after the returned lot (19.5% did not run; 37.9% won; 6.67 average starts per horse) Lane et al. (1987) TABLE 3: Tattersalls Yearling Sales 1987–1993: Summary <strong>of</strong> matched control study <strong>of</strong> yearlings returned for their wind 7,463 yearlings sold 78.8 examined by purchasers’ vets 1.65% referred to panel 0.67% failed 4: 1 colts: fillies (Sex ratio <strong>of</strong> all catalogued yearlings 1.27:1) 1987–1993 Racing Performance Aged 2–4 years Failures Ran 8.48 mean races Won mean 1.32 races Controls – (the 2 sold before and the 2 sold after the referred lot and <strong>of</strong> the same sex) Ran 13.71 mean races Won mean 2.18 races J. Griffiths Project (in preparation) 1987–1993 which are unfit or untrained and very <strong>of</strong>ten inspiratory noises will disappear with one or two lunging sessions. Panel members occasionally differ in their interpretation <strong>of</strong> the character <strong>of</strong> the inspiratory noise or on the grading <strong>of</strong> the endoscopic findings. For some years vendors were able to insure against their yearling being returned by the wind panel, either early in the year without a preliminary test or one month before selling following a lunging test by their own veterinary surgeon. The authors suspect that there were some dubious claims. In the Horses in Training Sales the veterinary surgeons <strong>of</strong> purchasers <strong>of</strong>ten lunge the horse before returning it to the panel. The horse with RLN may make a whistle or roar on the lunge but be silent when galloped in a straight line. TABLE 2: Tattersalls Yearling Sales 1987–1995: Summary <strong>of</strong> matched control study <strong>of</strong> yearlings returned for their wind 1987–1995 (9,524 yearlings sold) 78.8% examined by purchasers’ vets 1.56% referred to panel 0.65% failed 0.91% passed At least 3:1 colts: fillies 1987-1995 Racing Performance Aged 2–4 years Passes 10.85 mean races 1.87 wins Controls 9.09 mean races 1.41 wins+ Failures 7.32 mean races 0.97 wins* Controls 10.69 mean races 1.42 wins+ S. White Thesis, University <strong>of</strong> London * Significant difference; + Controls – one sold before and one after the lot referred to the panel and <strong>of</strong> the same sex Other upper airway conditions have included pharyngeal lymphoid hyperplasia <strong>of</strong> varying degrees. The more severe cases <strong>of</strong>ten make abnormal inspiratory sound, sometimes indistinguishable from the characteristic roar or whistle required by the Conditions <strong>of</strong> Sale. Dorsal displacement <strong>of</strong> the s<strong>of</strong>t palate was seen but none was permanent and no palatal deformities were found. One horse with epiglottic entrapment did not have RLN and was not returnable. Four cases <strong>of</strong> fourth branchial arch anomalies were identified. One <strong>of</strong> these showed no evidence <strong>of</strong> laryngeal asymmetry or RLN and was passed. Two were failed and returned to the purchaser and one was taken back by the vendor before the panel completed its examination. Two cases <strong>of</strong> right sided RLN, which did not have fourth branchial arch anomalies, were identified and returnable. Cases <strong>of</strong> thin, flimsy epiglottis were noted but were not among those which were failed. Three studies have been prepared for publication on the findings <strong>of</strong> Tattersalls’ panel. An interesting feature <strong>of</strong> the Table 1 findings is that those which were returned on the basis <strong>of</strong> sound only performed significantly less well than those which were returned with RLN. Figures from Tables 2 and 3 confirmed that the horses which were adjudicated as returnable by the panel, raced and won significantly less <strong>of</strong>ten than their sex matched controls sold in the same sale. The panel periodically review the modus operandi and diagnostic criteria. They have considered including other congenital and incurable 40
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