Transrectal Decompression As a New Approach for Treatment of Large Intestinal Tympany in Horses with Colic: Preliminary Results G

184 EQUINE VETERINARY EDUCATION / AE / APRIL 2013

Original Article Transrectal decompression as a new approach for treatment of large intestinal tympany in horses with colic: Preliminary results G. B. Scotti*,S.S.Lazzaretti,D.D.Zani† and M. Magri‡ Reparto di Chirurgia, Azienda Polo Veterinario di Lodi, Facoltà di Medicina Veterinaria, Università degli Studi di Milano, Italy; †Reparto di Radiologia, Azienda Polo Veterinario di Lodi, Facoltà di Medicina Veterinaria, Università degli Studi di Milano, Italy; and ‡Clinica Veterinaria Spirano, Spirano (BG), Italy. *Corresponding author email: [email protected]

Keywords: horse; gas; abdominal pain; colon; caecum

Summary important. Tympany commonly takes place in the colon or A common feature of colic in horses is tympany in the large caecum, less frequently occurring in the stomach or small intestine and medical treatment of this condition can be intestine and may be classified as primary or secondary; unsuccessful. In this article we describe and evaluate a new primary in the case of abnormal fermentation of ingesta and approach for decompression of large intestinal tympany in secondary if due to conditions interfering with normal intestinal equine colic patients using transrectal puncture. We evaluated gas transit and emptying (impaction, entherolithiasis, torsion horses showing colic symptoms and colonic or caecal and volvulus) (Mair 2002). The clinical manifestations tympany and the final diagnosis, complications and final associated with large colon or caecal tympany may include outcome were recorded for each horse. A special transrectal distension of the right or left paralumbar fossa, intermittent decompression device (TDD) was developed and used to pain, tachycardia, reduced borborygmi, presence of a ‘ping’ perform transrectal decompression (TD) by gas aspiration. In sound on auscultation-percussion and abnormal visceral order to assess pain reduction as a result of TD, heart rate (HR) distension on transrectal palpation (Edwards 2002; Hackett was recorded before and after the decompression procedure. 2002). Medical management of tympanic colic revolves Twenty-five horses were included in the study. In 17 cases, around stabilisation of pain (through the use of nonsteroidal tympany was recognised as primary in origin while in 8 it was anti-inflammatory drugs, a2 antagonists and opioid agents), secondary to other conditions. A total of 33 TDs were administration of metronidazole and mineral oil in order to performed and no horses developed short- or long-term reduce the number of gas-producing organisms and to coat complications. All horses were alive after the first month post the fermentable substrate (Mair 2002). Severe cases may be TD, while 5 died from diseases not related to TD. The managed with percutaneous decompression, placing a 16 TD could safely and easily be performed in all horses gauge needle in the right, or with more caution, in the left presenting tympany. Transrectal decompression can easily be paralumbar fossa (Hackett 2002). If the patient continues to be performed, 2 or even 3 times to treat a single colic episode by compromised, surgical management may be considered if using the transrectal device connected to a surgical aspirator. there are no financial constraints. Therefore, the purpose of this It was not possible from available information to relate the study is to describe and evaluate a new approach for timing of HR decrease to resolution of colic or to administration decompression of colonic and caecal tympany in equine of drugs because a retrospective study and all such data were colic patients by transrectal puncture. not readily accessible. Our clinical results support the relevance of the TD as an elective treatment of primary large Materials and methods intestinal tympany, emergency treatment of tympany Study design secondary to other surgical entities and as palliative treatment Medical records for adult horses referred for acute abdominal in surgical patients, in which surgery could not be achieved. disease from January 2008 to October 2010 were reviewed. At the time of admission, each horse underwent a clinical Introduction examination, including complete blood sample analysis, Acute diseases of the equine abdomen associated with signs transrectal palpation, nasogastric intubation for reflux of pain are commonly known as colic (Tinker et al. 1997). Colic evaluation and abdominal ultrasonography, using a 3.5 MHz syndrome is considered to be one of the most significant convex probe. Transrectal ultrasonography was also medical and surgical challenges in equine practice performed using a 5–8 MHz linear probe, in order to evaluate worldwide. Frequency of colic was estimated by Tinker et al. the degree of intestinal compromise and identify the position (1997) to be 10.6 episodes per 100 patients. A recent study for placement of the needle for transrectal decompression. (Voigt et al. 2009), related to the African equine population, Horses were included in the study if they showed abnormal has shown that 60% of colic cases were managed with visceral distension of the caecum and/or the colon medical treatment and, particularly, in 42% of cases, on transrectal palpation and presence of gas during abdominal distension was present during clinical abdominal and transrectal ultrasonographic examination. examinations. Considering the frequency (Voigt et al. 2009) The final diagnosis, number of decompressions, presence of and difficulties in diagnostic and therapeutic approaches of complications and final outcome were recorded for each this condition (Hackett 2002), this pathology is clinically very horse. Moreover, horses were re-evaluated at the time of

Fig 1: Transrectal decompression device, safety position, lateral view. The needle is located within the cylinder because the spring mechanism is hooked at its caudal site. The TDD can be safely introduced in this position and removed from the anus.

Fig 3: Post mortem laparoscopic view of the beginning of suction during transrectal decompression. A horse that had died for other reasons was placed in right lateral recumbency and the ascending colon inflated with air with a transabdominal cannula. Note the needle between the rectal wall on the left and ascending colon on the right. Fig 2: Transrectal decompression device, released position, dorsal view. The needle is released at the left end of the cylinder and a connection for the surgical aspiration tube is present at the right end. This position is achieved releasing the spring mechanism only when the TDD is in its final position against the rectal wall, in order to start the decompression.

discharge and one month later. All subjects received a clinical examination, complete blood sample analysis, transrectal palpation, abdominal and transrectal ultrasonography, nasogastric intubation and an abdominocentesis. Horses that died or were subjected to euthanasia had a post mortem examination.

Description of the technique Patients were confined in a stock and sedated using i.v. infusion of detomidine chlorhydrate (Domosedan)1 at 0.01 mg/kg bwt. Hyoscine n-buytlbromide (Buscopan)2 was also administered at a dose rate of 0.2 mg/kg bwt in all horses to treat intestinal spasms. In order to perform a safe transrectal decompression, a special device was designed (TDD)3 (Fig 1). The device was composed of a central metallic cylinder with an internal cavity. One end of the cylinder contained an attachment to connect to an aspiration tube and the other Fig 4: Post mortem laparoscopic view of the last phase of suction end to an opening for needle exit. An 18 gauge needle was during transrectal decompression. Note the diminution of the distension and the returning of the ascending colon on its normal located within the cylinder and could be released by a spring position after the decompression. mechanism located either side of the cylinder using 2 free fingers (Fig 2). Due to the structure of the device and needle shielding, it could safely be inserted through the anus. Once the device was well positioned in the rectum, adjacent to the decompression time. Once aspiration was completed and to gas distended organ, the needle was sprung into the avoid lacerations or punctures of the bowel, the needle was tympanic viscus in order to commence gas aspiration (Figs 3 retracted into the cylinder and safely removed from the and 4). In all horses included in this study, a surgical aspirator rectum. In the case of tympany recurrence, aspiration was (Aspi-Vet)4 was used to obtain negative pressure and reduce repeated as needed.

Statistical analysis abscess formation, cellulitis or peritonitis. In 2 horses (Horse 1 with A Student’s t test was used to compare the average of colitis and Horse 4 with large colon torsion), evaluation was not HR measured before and after TD, in order to establish a possible because of advanced intestinal deterioration. Heart possible relationship between decompression and pain levels rates taken from 19 of the 25 horses were then compared of the horse. The test was considered significant if P<0.01. before and after treatment. The average heart rate prior to treatment was 54 beats/min (range 40–80 beats/min), while the Results average heart rate post decompression was 45 beats/min (range 40–60 beats/min). Twenty-five horses were included in the study: 9 Warmbloods, 3 French Warmbloods, 3 Arabians, 3 Criollos, 2 Thoroughbreds, 1 Spanish Warmblood, 1 Italian Draught Horse and 1 Haflingher. Discussion There were 12 mares, 11 geldings and 2 stallions with a mean In the literature, many studies show that, in a large percentage age of 11.8 years (range 1–20). Seventeen of 25 horses (68%) of equine acute abdominal examinations, it was not possible presented tympany as a primary entity. Of these, 11 horses to establish a precise diagnosis and most horses responded to (44%) presented colonic tympany, 4 (16%) colonic and caecal medical treatments or resolved spontaneously. These cases tympany and 2 (8%) caecal tympany. In 8 of 25 horses (32%), are frequently considered as spasmodic/gas colics (Tinker tympany was secondary. Of these, 2 (8%) presented et al. 1997; Archer and Proudman 2006; White 2009) and we nephrosplenic entrapment, 2 (8%) colonic torsion, 2 (8%) speculate that abdominal distension could be present in the presented large colon displacement, one (4%) epiploic majority of these cases. Moreover, to our knowledge, any foramen entrapment and one (4%) presented caecal study considers the frequency of meteorism during surgical impaction. Twenty (80%) horses were managed with TD in pathologies of the colic syndrome. Due to the frequency of combination with a medical treatment, 3 (12%) were managed abdominal distension in equine acute abdominal firstly with TD and subsequently with a laparotomy and 2 (8%) examinations, as highlighted by Voigt et al. (2009) and the were subjected to euthanasia because surgery was not an necessity to develop new therapeutic techniques in option. Nephrosplenic entrapments were treated firstly with TD management of these cases, a preliminary study to describe associated with phenylephrine chlorhydrate i.v. infusion (15 mg the transrectal decompression procedure was performed. diluted in 1 l of 0.9% NaCl during 15 min) and exercise. A total of 33 TD were performed: 24 (73%) TD were performed on the large Pain evaluation colon, 5 (15%) TD on the caecum and 4 (12%) TD on both. A In 19 of the 25 horses, TD was associated with a reduction in HR minimum of one and maximum of 3 treatments were performed following treatment. The correlation between reduction of in a single case: 3 horses received 3 decompressions because pain and reduction of HR has already been previously of a recurrent primary colonic tympany, while 4 out of 25 observed by Van Harreveld and Gaughan (2002). During received 2 decompressions showing respectively one case of clinical examinations, all horses were administered a2 primary colonic tympany, primary caecal tympany, large antagonists (detomidine chlorhydrate, Domosedan)1 and colon displacement and nephrosplenic entrapment. Normally, spasmolytics (hyoscine n-buytlbromide, Buscopan)2 in order to each decompression was accomplished in a range of time reduce pain and intestinal spasms. In the literature, hyoscine between 20 s and 2 min (median time 1 min). None of the horses n-buytlbromide has previously shown a strong analgesic treated demonstrated short- or long-term complications. In the and spasmolytic actions (Murray 2004) and, due to its first month follow-up post treatment, 20 out of 25 horses were anti-cholinergic action, administration of this drug has alive (80%), while 5 (20%) died from diseases not related to the been described to induce a transient tachycardia after post mortem TDD. The causes of death were established at administration, which may have altered our findings. The examination: one horse was affected by colitis, one by an effect of this tachycardia would most likely be countered by epiploic foramen entrapment of small intestine, one by the concurrent administration of detomidine chlorhydrate, interstitial pneumonia, while 2 in which surgery was not an which would cause a reduction in heart rate to the original option were subjected to euthanasia (one horse with large baseline value (Pimenta et al. 2011). It was not possible from Table 1 colon torsion, one with large colon displacement) ( ). Of available information to relate the timing of HR decrease to these, 4 horses (80%) received only one decompression while resolution of colic or to administration of drugs, because this one out of 5 (20%) received 2 decompressions. During was a retrospective study and all such data was not readily necroscopy, no changes were found on the decompression available. sites of 3 horses, including no evidence of haemorrhage, Indications of the technique TABLE 1: Follow-up, clinical and examinations post mortem In the 17 cases of primary colonic or caecal tympany, the of patients technique was used as an elective treatment. Moreover, 20 Clinical or post horses were managed with TD and medical treatment, Follow-up Cases mortem examinations showing that TD was useful in all primary tympany cases and in 3 cases where tympany was secondary. In our population we Horses alive 0/25 (80%) • Absence of signs of complications performed 24 TD for the treatment of large colon tympany and Horses died or 5/25 (20%) • Colitis although the majority of these cases were primary, 5 were subjected to • Epiploic foramen entrapment recurrent and managed with multiple TD. Complete resolution euthanasia of small intestine was obtained showing that TD could be easier to perform and • Polmonitis more effective than percutaneous decompression during • Euthanasia (colon torsion and colon displacement) large colon tympany. In 4 cases of large colon and caecal tympany, TD was accomplished on both viscera. This finding

could be potentially useful in order to minimise patient cases. Six of 25 patients received repeated decompressions discomfort, time of realisation and possibility of contamination. because of the recurrence of the tympany. Although in these In the cases of tympany secondary to other primary cases explorative laparotomy was recommended in order to diseases, this technique was used to stabilise the horse diagnose primary surgical entities (Dabareiner and White 1997; and relieve pain. Some colonic and caecal diseases, such as Mair 2002, 2009; Hackett 2002; Moore and Hardy 2009), in our impaction, enterolithiasis, torsion and volvulus, are known to be experience it was possible to resolve the tympany alone with associated with intestinal gas accumulation (Fischer 2002; TD. To support our observations on TD safety, in human Hackett 2002; Hanson 2002). As regards colon volvuli, the medicine transrectal ultrasound-guided prostate biopsy highest intra-luminal pressures were measured during (TRUSP Bx) is the standard method for diagnosing prostate strangulated volvuli (Moore et al. 1996). The efficacy of cancer. In human medicine, the procedure involves taking 10 percutaneous decompression has been previously described or more separate biopsies transrectally but, despite the size of in relation to nephrosplenic entrapment, where puncture is the needle and large number of punctures, only 2.4% of the performed at the left paralumbar fossa in order to evacuate patients developed an infective complication (Madden et al. the excess of gas accumulation into the colon secondary to its 2011). None of the horses in this study developed any signs of displacement (Rakestraw and Hardy 2006). In our population, 2 peritonitis subsequent to the procedure or in the case of cases of nephrosplenic entrapment were successfully multiple TDs. At follow-up, 5/25 patients were dead because managed with TD, phenylephrine infusion and exercise, of other primary pathologies not related to the TD. Gross highlighting a possible utilisation during cases associated with evaluations at post mortem examination failed to reveal any severe gas distension. As previously reported (Fischer 2002; signs of haemorrhage, abscess formation, cellulitis or peritonitis Hackett 2002; Hanson 2002), we also found a strong association in 3 horses with no advanced intestinal deterioration. In between tympany and other large intestinal diseases; the literature, complications after caecal percutaneous furthermore, in many cases, TD was useful in reducing the high decompression are rare but colonic percutaneous degree of meteorism associated with these conditions in order decompression is described as more dangerous and more to allow complete rectal examinations. difficult to perform (Mair 2002). In our study, multiple and We introduced TD to our ‘colic protocol’ as an emergency repeated decompressions were performed on the large colon treatment in order to stabilise the patient before surgery. Only 3 but also on the caecum and we found both TD very safe and horses managed with laparotomy were previously treated with easy to perform, especially compared to decompression TD. Despite a positive response after TD in these horses, the low performed at the left paralumbar fossa. Compared to the number of cases is not sufficient to demonstrate any percutaneous decompression, we believe TD could be safer correlation. One of the advantages of presurgical intestinal during aspiration because the operator is able to feel the decompression, which has been highlighted by previous ventral movement of the needle while the viscera is returning studies on percutaneous decompression (Rakestraw 2002), is to its normal anatomical position and shape, avoiding visceral the decrease in volume of the affected intestine, resulting in less wall injuries. Nevertheless, the low number of cases in our study compression on the diaphragm when the horse is placed in is not sufficient to completely exclude possible complications dorsal recumbency. This can be associated with alteration of after TD. the ventilation and perfusion ratios, often resulting in In our experience, medical treatments and evacuation of hypoventilation, hypoxaemia and hypercapnia (Gleed 2002). the rectum prior to performing the procedure facilitate the TD. Hypotension secondary to poor venous return and concurrent In agreement with the literature (Rantanen and McKinnon reduced cardiac output is a relevant alteration during acute 1998), in our study we found the use of transrectal intestinal obstructions (Lantz 1981; Moore and White 1982). We ultrasonography invaluable for confirmation of the presence of speculate that decompression may reduce the magnitude of gas in the intestine and in reducing the risk of perforation of hypotension in horses suffering acute abdomen associated large blood vessels or direct peritoneal cavity needle with colon and/or caecal meteorism before surgery. In cases penetration. Theoretically, TD could be safely performed where surgery was not an option, TD was used as a palliative using an 18 gauge needle alone, introducing it through the technique to relieve pain and also in attempting to establish anal sphincter while protected by the operator’s hand. normal organ position by evacuating the gas, as previously Nevertheless, many complications could be associated with described for the percutaneous technique (Dallap Schaer and this approach, especially difficulty in managing the needle Orsini 2008). inside the rectum without causing rectal wall damage or an operator injury and, for these reasons, we developed a special device (TDD). Subsequently, we highlight that the TDD, thanks Safety evaluation of the technique to its cylindrical shape, can be easily inserted through the anal The complications considered for the evaluation of sphincter and is easily manipulated due to the spring the safety of the technique were adapted from those mechanism that can be safely activated by 2 fingers, allowing described for the percutaneous decompression, with relation placement and retraction of the needle at the desired point, to local peritonitis or abscess formation at the perforating site, thereby decreasing contamination. We used an 18 gauge diffuse peritonitis and cellulitis (Mair 2002; Dallap Schaer and needle connected to a surgical aspirator in order to achieve Orsini 2008). An association between TD and acute onset the fastest decompression with the lowest risks of trauma and peritonitis has been previously reported by Mair (2002). contamination. Some authors have previously used 14 or 16 However, this study did not describe the use of transrectal gauge needles when performing caecal or colonic ultrasonography for determination of the needle placement, percutaneous decompressions (Hackett 2002; Moore and needle size or concurrent use of an aspirating device. In Hardy 2009). A larger needle could be used, but we are of the contrast with the study performed by Mair (2002), we found opinion that this would not allow a faster decompression even our technique safe in the 33 decompressions performed on 25 in a uncomfortable horse, because normally TD is already

performed in a median time of 1 min and a larger needle may Hackett, R.P. (2002) Primary colonic tympany. In: Manual of increase the risk of contamination. The use of a surgical Equine Gastroenterology, Eds: T. Mair, T. Divers and N. Ducharme, W.B. Saunders, London. pp 292-293. aspirator is more effective in decreasing the amount of residual gas when no or little difference between intra-luminal and Hanson, R.R. (2002) Diseases of the large colon that can result in colic. In: Manual of Equine Gastroenterology, Eds: T. Mair, T. Divers and atmospheric pressures is still present. Moreover, one way N. Ducharme, W.B. Saunders, London. pp 279-284. communication between the distended viscera and rectum Lantz, G.C. (1981) The pathophysiology of acute mechanical small will be achieved because a negative pressure is applied, thus bowel obstruction. Comp. Cont. Educ. Pract. Vet. 3, 910-918. minimising contamination. Madden, T., Doble, A., Aliyu, S.H. and Neal, D.E. (2011) Infective complications after transrectal ultrasound-guided Conclusion prostate biopsy following a new protocol for antibiotic prophylaxis aimed at reducing hospital-acquired infections. BJU Int. 108, Although, in our opinion, the technique is safe and effective for 1597-1602. the treatment of colonic and caecal tympany, the limitations Mair, T.S. (2002) Other conditions, Abdominal distention in the of our study include the low number of patients considered, adult horse. Gastro-intestinal tympany (distention\tympanitic\ lack of control cases and absence of detailed clinical flatulent colic). In: Manual of Equine Gastroenterology, Eds: parameters about hospitalisation and resolution of each T. Mair, T. Divers and N. Ducharme, W.B. Saunders, London. pp 317-319. disease. Further studies are necessary to improve the Mair, T.S. (2009) Treatment of flatulence and tympany. In: The Equine technique and obtain more accurate information regarding Acute Abdomen, 2nd edn., Eds: N.A. White, J.N. Moore and the application to each specific entity involved in the colic T.S. Mair, Teton Newmedia, Jackson. p 302. syndrome of the horse. Finally, we hope this new approach to Moore, J.N. and White, N.A. (1982) Acute abdominal disease: the tympany of the large intestine could be introduced in an pathophysiology and preoperative management. Vet. Clin. N. Am.: equine colic decisional algorithm. Large Anim. Pract. 4, 61-78. Moore, J.N. and Hardy, J. (2009) Specific diseases, cecal tympany. In: Equine Acute Abdomen, II edn., Eds: N.A. White, J.N. Moore and Authors’ declaration of interests T.S. Mair, Teton Newmedia, Jackson. pp 618-619. No conflicts of interest have been declared. Moore, R.M., Hance, S.R. and Hardy, J. (1996) Colonic luminal pressure in horses with strangulating and nonstrangulating obstruction of the large colon. Vet. Surg. 25, 134-141. Manufacturers’ addresses Murray, J.M. (2004) Drugs acting on the gastrointestinal system. In: 1Orion Corporation, Orionintie 1A, Espoo, Finland. Equine Clinical Pharmacology. Eds: J.J. Bertone and L.J.I. Horspool, Saunders Elsevier, Philadelphia. p 110. 2Boehringer Ingelheim IT Spa, Via Lorenzini 8, Milano, Italy. 3Blacksmith SNC, Via Monaco 16, Ciserano (BG), Italy. Pimenta, E.L., Teixeira Neto, F.J., Sá, P.A., Pignaton, W. and Garofalo, N.A. (2011) Comparative study between atropine and 4Samed Elettromedicali SRL, Merlino (LO), Italy. hyoscine-N-butylbromide for reversal of detomidine induced bradycardia in horses. Equine Vet. J. 43, 332-340. References Rakestraw, P.C. (2002) Preoperative preparation. In: Manual of Equine Gastroenterology, Eds: T. Mair, T. Divers and N. Ducharme, Archer, D.C. and Proudman, C.J. (2006) Epidemiological clues to W.B. Saunders, London. pp 140-141. preventing colic. Vet. J. 172, 29-39. Rakestraw, P.C. and Hardy, J. (2006) Alimentary system, large Dabareiner, R.M. and White, N.A. (1997) Diseases and surgery of the intestine. In: The Equine Surgery, 3rd edn., Eds: J.A. Auer and cecum. Vet. Clin. N. Am.: Equine Pract. 13, 303-315. J.A. Stick, Saunders-Elsevier, Missouri. pp 436-465. Dallap Schaer, B. and Orsini, J.A. (2008) Gastrointestinal System, Rantanen, N.W. and McKinnon, A.O. (1998) Equine Diagnostic Diagnostic and therapeutic procedures. In: Equine Emergencies, Ultrasonography, Williams and Wilkins, Baltimore. Treatment and Procedures, Eds: J.A. Orsini and T. Divers, W.B. Saunders, Missouri. pp 105-106. Tinker, M.K., White, N.A., Lessard, P., Thatcher, C.D., Pelzer, K.D., Davis, B. and Carmel, D.K. (1997) Prospective study of equine colic incidence Edwards, R.B. (2002) Cecal diseases that can result in colic. and mortality. Equine Vet. J. 29, 448-453. Cecal tympany. In: Manual of Equine Gastroenterology, Eds: T. Mair, T. Divers and N. Ducharme, W.B. Saunders, London. Van Harreveld, P.M. and Gaughan, E.M. (2002) Clinical evaluation of pp 268-269. the colic case. In: Manual of Equine Gastroenterology. Eds: T. Mair, T. Divers and M. Ducharme, Saunders, London. pp 107-112. Fischer, A.T. (2002) Enterolithiasis. In: Manual of Equine Gastroenterology, Eds: T. Mair, T. Divers and N. Ducharme, W.B. Saunders, London. Voigt, A., Saulez, M.N., Donnellan, C.M. and Gummow, B. (2009) Causes pp 293-296. of gastrointestinal colic at an equine referral hospital in South Africa (1998-2007). J. S. Afr. Vet. Ass. 80, 192-198. Gleed, R.D. (2002) Anesthesia for colic surgery. In: Manual of Equine Gastroenterology, Eds: T. Mair, T. Divers and N. Ducharme, White, N.A. (2009) Colic: prevalence, risk factors and prevention. Proc W.B. Saunders, London. pp 145-155. 7th Ann. Res. Symp. AAEP, 297-307.

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Reef, V. and Genovese, R. (2003) Soft tissue injuries of the pastern. In: Wilderjans, H., Boussauw, B., Madder, K. and Simon, O. (2003) Diagnosis and Management of Lameness in the Horse, Eds: M. Ross Tenosynovitis of the digital flexor tendon sheath and annular and S.J. Dyson, Saunders, St Louis. pp 716-723. ligament constriction syndrome caused by longitudinal tears Smith, M.R.W. and Wright, I.M. (2006) Noninfected tenosynovitis of the in the deep digital flexor tendon: a clinical and surgical report digital flexor tendon sheath: a restrospective analysis of 76 cases. of 17 cases in Warmblood horses. Equine Vet. J. 35, 270- Equine Vet. J. 38, 134-141. 275.