Highlights of recent clinically relevant papers

Preoperative diagnostic methods for digitalflexor tendon sheath pathologyA.R. Fiske-Jackson and colleagues from the RoyalVeterinary College, UK, have recently reported the findingsof their study on the use of intrathecal analgesia andcontrast radiography as preoperative diagnostic methodsfor digital flexor tendon sheath pathology.

This study (Fiske-Jackson et al. 2012) found that contrastradiography is a useful tool for the diagnosis of pathologywithin the digital flexor tendon sheath. Currently,ultrasonography is the mainstay of diagnosis for manicaflexoria and marginal tears of the deep digital flexortendon (DDFT). However, the sensitivity of this technique isreported to be 38% and 71%, respectively. Use of a contrasttenogram increased the sensitivity for diagnosis of manicaflexoria tears to 96% (specificity 80%). Marginal DDFT tearswere diagnosed, using this technique, with a sensitivityof 57% (specificity 84%). This study also evaluated theresponse to intrathecal analgesia and found that horseswith DDFT tears were significantly more likely to have apositive response to intrathecal analgesia than those withmanica flexoria tears. This technique is a useful additionto the diagnostic evaluation of manica flexoria tears inhorses.

Outbreak of besnoitiosis in donkeysS.L. Ness and colleagues from Cornell University, USA,have recently investigated an outbreak of besnoitiosis indonkeys in northeastern Pennsylvania.

This observational study (Ness et al. 2012) describesthe clinical, endoscopic and serological features ofan outbreak of besnoitiosis in 2 donkey operations innortheastern Pennsylvania, and reports the outcome ofattempted treatment of one naturally infected individual.A total of 29 donkeys (Equus asinus) were examinedfor lesions suggestive of besnoitiosis in an outbreakinvestigation and information was collected regardingthe history and signalment of animals on each premises.Rhinolaryngoscopy was performed to identifynasopharyngeal and laryngeal lesions. Serum sampleswere collected for immunofluorescent antibody testingand immunoblotting for Besnoitia spp. Skin biopsy sampleswere obtained from 8 animals with lesions suggestiveof besnoitiosis for histological examination. Quantitativerealtime PCR assay for Besnoitia spp. was performed ontissue samples from 5 animals.

Besnoitiosis was confirmed in 6 of the 8 suspectedcases. The most common lesion site was the nares,followed by the skin and sclera. Donkeys with clinical signs

of disease had higher serum antibody titres and testedpositive for a greater number of immunoblot bands thandid donkeys without clinical signs of disease. All animalsevaluated by PCR assay tested positive. Putative riskfactors for disease included age and sex. Ponazuril wasnot effective at treating besnoitiosis in a naturally infecteddonkey. The authors concluded that knowledge of clinicaland serological features of besnoitiosis in donkeys will assistclinicians in the diagnosis and prevention of this disease indonkey populations. Besnoitiosis may be an emergingdisease of donkeys in the United States.

Ascending colon displacementK.F. McGovern from Donnington Grove VeterinarySurgery, UK, and colleagues have recently published thisretrospective case series of 127 horses with suspected largecolon displacement (McGovern et al. 2012).

The aim of this study was to determine the success ofmedical management of suspected displacement of theascending (large) colon in horses.

Medical records (January 1998 to September 2008)of horses admitted for colic were reviewed. Suspectedlarge colon displacement was diagnosed from clinicalexamination and in some cases, subsequent surgicalexamination. Medically managed horses were exercisedand administered intravenous fluids and analgesia. Horseswith suspected left dorsal displacement (LDD) of the largecolon were also administered phenylephrine.

Medical management had a high success rate fortreatment of suspected right dorsal displacement (RDD)(64%) and LDD (76%) of the large colon; one horses died, 3were subjected to euthanasia and 36 horses had surgery.Of 127 horses treated medically or surgically for a colondisplacement, 94% survived to hospital discharge.

The authors concluded that horses with suspectedRDD or LDD of the large colon may respond to medicalmanagement including exercise.

Risk factors for colic in hospitalised horsesL.A. Patipa and colleagues from the University of Georgia,USA, have published the results of a study to evaluate theincidence of colic and the risk factors for colic in equidshospitalised for ocular disease (Patipa et al. 2012).

This retrospective observational study comprised 337equids (317 horses, 19 ponies and one donkey) hospitalisedfor ocular disease. The medical records of equidshospitalised for >24 h for treatment of ocular diseasebetween January 1997 and December 2008 werereviewed. Information from only the first hospitalisation was

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EQUINE VETERINARY EDUCATION 377Equine vet. Educ. (2012) 24 (8) 377-378doi: 10.1111/j.2042-3292.2012.00446.x

© 2012 EVJ Ltd

used for equids that were hospitalised for ocular disease onmore than one occasion. Information gathered includedthe signalment, the type of ocular lesion and the treatmentadministered, and any colic signs recorded duringhospitalisation as well as the severity, presumptivediagnosis and treatment of the colic. Statistical analysiswas used to identify any risk factors for colic in equidshospitalised for ocular disease.

The authors found that 72 of 337 (21.4%) equidshospitalised for ocular disease had signs of colic duringhospitalisation. Most equids (59.7% [43/72]) had mildsigns of colic, and most (87.5% [63/72]) were treatedmedically. Ten of 72 (13.9%) equids with colic had a caecalimpaction. Risk factors for colic in equids hospitalised forocular disease were age (0–1 year and �21 years) and anincreased duration of hospitalisation (�8 days). There wasa high incidence of colic in equids hospitalised with oculardisease in this study. Findings from this study may helpidentify equids at risk for development of colic and therebyhelp direct implementation of prophylactic measures.

Myenteric ganglionitis and recurrent colicK.R. Blake and colleagues from the University of California-Davis, USA, have recently published a case reportdescribing myenteric ganglionitis as a cause of recurrentcolic in an adult horse (Blake et al. 2012).

A 10-year-old Lipizzaner stallion was evaluated over thecourse of 1.5 years because of intermittent, recurrent colic.The horse was initially treated medically for gastric ulcers;dietary changes were made, and a deworming protocolwas instituted, without resolution of colic episodes.Subsequently, the horse underwent exploratory celiotomyand a large colon volvulus was identified with diffusecolonic wall thickening. A pelvic flexure biopsy sample wassubmitted for histological examination, which revealedlymphocytic (CD3-positive T cells) myenteric ganglionitis(MG). The horse developed a caecal impaction aftersurgery which did not resolve despite aggressive medicalmanagement; subsequently a complete caecal bypasswas performed. Caecal and colonic wall biopsy sampleswere evaluated histologically and confirmed the diagnosisof MG. After surgery, the horse developed a large colonimpaction, which initially responded to aggressive medicaltreatment, and the horse was discharged.

Despite rigorous feed restrictions and prokinetic andcorticosteroid treatment, the horse continued to have signsof colic and was subjected to euthanasia 3 weeks afterdischarge from the hospital because of a recurrent largecolon impaction. Intestinal biopsy samples obtained at thetime of death revealed chronic changes in intramuralganglia consistent with generalised MG. The authorsconcluded that MG is a rare disease in horses, causinggastrointestinal motility dysfunction and signs of colic,which is challenging to diagnose and treat successfully.Further studies are needed to identify the aetiology of thisdisease and to explore treatment options.

Equine pituitary pars intermedia dysfunctionin aged horsesT.W. McGowan and colleagues have reported the findingsof their study performed on a population of aged horses inQueensland, Australia.

This study (McGowan et al. 2012) is the firstepidemiological study of pituitary pars intermediadysfunction (PPID) in an aged population of horses (>15years), which is not based on the analysis of clinical records.The aim was to establish the prevalence, risk factorsand predictive clinical signs for PPID in a group of agedhorses using seasonally adjusted basal plasmaadrenocorticotrophic hormone (ACTH) concentrations.Owner reported data was initially used based on a postalquestionnaire. All aged horses were subsequently examinedand a blood sample taken for routine haematology,biochemistry, ACTH and alpha melanocyte-stimulatinghormone (a-MSH). The prevalence of PPID was found to be21.2% in aged horses. Previous studies have looked atowner-reported hirsutism as a means of diagnosis of PPID; inthis study owner reported hirsutism was 16.7%. Despite analysisof numerous clinical and historical signs, and biochemicaland haematological variables, the only finding found to beconsistent with a diagnosis of PPID was owner-reportedhirsutism. There was also found to be an increasing incidenceof PPID with every year of age over 15 years. The highprevalence of this condition in aged horses and increasing riskwith advancing age are consistent with a degenerativecondition. Aged horses with consistent clinical and historicalsigns, especially those with owner-reported hirsutism shouldbe candidates for further investigation of possible PPID.

S. WRIGHTEVE Editorial Office

References

Blake, K.R., Affolter, V.K., Lowenstine, L.J., Vilches-Moure, J.G. and leJeune, S.S. (2012) Myenteric ganglionitis as a cause of recurrentcolic in an adult horse. J. Am. Vet. Med. Ass. 240, 1494-1500.

Fiske-Jackson, A.R., Barker, W.H.J., Eliasher, E., Foy, K. and Smith, R.K.W.(2012) The use of intrathecal analgesia and contrast radiography aspreoperative diagnostic methods for digital flexor tendon sheathpathology. Equine Vet. J. Epub ahead of print 6 May 2012 doi/10.1111/j.2042-3306.2012.00573.x

McGovern, K.F., Bladon, B.M., Fraser, B.S. and Boston, R.C. (2012)Attempted medical management of suspected ascending colondisplacement in horses. Vet. Surg. 41, 399-403.

McGowan, T.W., Pinchbeck, G.P. and McGowan, C.M. (2012)Prevalence, risk factors and clinical signs predictive for equinepituitary pars intermedia dysfunction in aged horses. Equine Vet.J. Epub ahead of print 18 May 2012 doi/10.1111/j.2042-3306.2012.00578.x

Ness, S.L., Peters-Kennedy, J., Schares, G., Dubey, J.P., Mittel, L.D.,Mohammed, H.O., Bowman, D.D., Felippe, M.J., Wade, S.E., Shultz, N.and Divers, T.J. (2012) Investigation of an outbreak of besnoitiosis indonkeys in northeastern Pennsylvania. J. Am. Vet. Med. Ass. 240,1329-1337.

Patipa, L.A., Sherlock, C.E., Witte, S.H., Pirie, G.D., Berghaus, R.D. andPeroni, J.F. (2012) Risk factors for colic in equids hospitalized forocular disease. J. Am. Vet. Med. Ass. 240, 1488-1493.

© 2012 EVJ Ltd

378 Highlights of recent clinically relevant papers