Pharmacokinetics of the anticonvulsant levetiracetam in neonatal foals

K. D. MacDonald, K. A. Hart, J. L. Davis, L. J. Berghaus and S. Giguère

This randomised crossover study aimed to describe the pharmacokinetics of levetiracetam in neonatal foals.  Six healthy Quarter Horse foals aged ≤1–3 days were recruited into the study and administered a single 32 mg/kg bwt dose of levetiracetam either intravenously (IV) or intragastrically (IG); the dose of which was extrapolated from pharmacokinetic data reported for adult horses.  In order to determine plasma levetiracetam concentrations all foals were blood sampled at 0, 5, 10, 15, 20, 35, 45, 60 and 90 minutes and 2, 3, 4, 6, 8, 10, 12, 24, 36 and 48 hours after administration. There were no apparent adverse effects associated with administration of the levetiracetam and plasma concentrations remained within the proposed therapeutic range (5–45 mg/L) and above the proposed target concentration (35 mg/L) for at least 12 hours for both IV and IG administration.  Bioavailability for IG administration was excellent, and there was no significant difference in the pharmacokinetic variables between IV and IG administration. 

Bottom line: administering levetiracetam to neonatal foals at a dose of 32 mg/kg bwt IV or orally twice daily is likely to maintain therapeutic plasma concentrations.

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Diagnosis, treatment and outcome of cranial nuchal bursitis in 30 horses

A. L. Bergren, G. A. Abuja, K. A. Bubeck, T. J. P. Spoormakers and J. M. García-López

This retrospective case series analysed medical records of horses diagnosed with cranial nuchal bursitis to further characterise associated diagnostic, management and prognostic factors. Thirty horses met the inclusion criteria, 21 of which were geldings and 9 mares.  The most common presenting clinical signs were swelling over the cranial nuchal bursa, pain upon poll palpation, reduced flexion of the neck and abnormal head carriage.  Radiographs were obtained in 27/30 cases; 22 of which had radiographic abnormalities.  All horses underwent ultrasonography, which showed synovial effusion in most cases.

Ten horses were treated with medication only (box rest and NSAIDs or intrabursal injection of corticosteroids), 16 underwent surgery (bursoscopic debridement and lavage) and 4 underwent surgical treatment following failed medical management. Of the 24 horses that had follow-up information available, 10 had recurrence of clinical signs; the most common of which was residual swelling of the poll region.  Horses that underwent surgery after a failed response to medical treatment were more likely to have recurrence of clinical signs, whilst horses that underwent surgical treatment only were less likely to have recurrence. There was no significant difference between the different treatment groups and the likelihood of return to their previous level of work.

Bottom line: Horses with cranial nuchal bursitis have a fair prognosis for return to their previous level of work, but recurrence of clinical signs is common. 

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Effectiveness of furosemide in attenuating exercise-induced pulmonary haemorrhage in horses when administered at 4- and 24-h prior to high-speed training

 H. K. Knych, W. D. Wilson, A. Vale, P. H. Kass, R. M. Arthur & J. H. Jones

This study aimed to investigate the efficacy of two furosemide dosing regimens in the reduction of EIPH severity in racehorses. Fifteen Thoroughbreds in training with an unknown EIPH history were recruited into the study and randomly assigned to one of the three following treatment protocols which were to be administered prior to a mock 5 furlong race: 5 mL of 0.9% NaCl i.v. 4 h prior to racing, 250 mg of furosemide i.v. 4 h prior to racing or 250 mg furosemide i.v. 24 h prior to racing.  Each group was eventually subjected to each treatment protocol with a 2-week minimum wash-out period in between.  One hour after racing horses underwent airway endoscopy and were assigned an EIPH grade (0–4) by a clinician blinded to the treatment protocol.  Video footage of the endoscopic examinations were later viewed and graded by three further clinicians.  A blind bronchoalveolar lavage (BAL) was performed on each horse immediately after endoscopic examination.

EIPH grades were significantly lower in the 4-h furosemide group compared to the 24-h furosemide group. BAL RBC counts were significantly higher in the saline-treated group when compared to the 4-h furosemide group.  Although there was no significant difference between RBC counts of the saline and 24-h furosemide groups, this was also the case between the 4-h furosemide and 24-h furosemide treatment groups.

Bottom line:  Administering furosemide 4 h prior to racing appears to be more effective at reducing EIPH severity than if administered 24 h prior to racing.

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Comparison of two blood sampling techniques for the determination of coagulation parameters in the horse: Jugular venipuncture and indwelling intravenous catheter

C. J. Mackenzie, C. M. McGowan, G. Pinchbeck & H. B. Carslake

This prospective study aimed to compare coagulation parameters of blood collected by direct jugular venipuncture and through an indwelling intravenous catheter (IVC).  Fifty-five horses admitted to a referral hospital over a 5-month period in 2015 were included; all of which had a 14-gauge polyurethane IVC placed in their jugular vein. Horses underwent paired blood sampling using both techniques, with 10 mL of blood being drawn and discarded from the IVC prior to sample collection.  Whole blood prothrombin time, fresh plasma prothrombin time, activated partial thromboplastin time, stored plasma antithrombin activity, fibrinogen concentration and D-dimer concentration were then measured accordingly.

Bland–Altman analysis which showed that all parameters excluding antithrombin and D-dimers had good agreement between the two sampling techniques.  The sensitivity and specificity of IVC sampling when compared to direct venipuncture was high. The poor agreement between direct venipuncture and IVC sampling for antithrombin and D-dimer measurement supports the use of venipuncture when these particular parameters are being measured.

Bottom line:  Blood sampling through an IVC is an acceptable technique when assessing most coagulation parameters.

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Open standing castration in Thoroughbred racehorses in Hong Kong: Prevalence and severity of complications 30 days post-castration 

S.M. Rosanowski, F. MacEoin, R.J.T.Y. Graham & C.M. Riggs

This retrospective cohort study investigated the prevalence of post-operative complications following routine open, standing castration in a closed population of Thoroughbreds in Hong Kong. Data from 250 horses castrated over a 5-year period were analysed in order to determine the prevalence of complications in the 30-day post-operative period. Sixty percent of horses (n = 150) experienced complications, which is up to three times higher than previously reported.

56.7% (n = 85) of complications were classified as mild (e.g. seroma formation, mild infection, mild colic). Thirty-eight percent (n = 57) of complications were classified as moderate (e.g. seroma formation requiring digital opening of the wound, funiculitis, loose faeces or moderately painful colic) and 5.3% (n = 8) of complications were classified as severe (e.g. pyrexia, excessive and prolonged haemorrhage, peritonitis). There was a significant difference between complication severity and time to return to galloping and racing.

Despite variations in technique such as ligating the testicular vessels, performing scrotal ablation etc., post-operative care was reportedly within standard practices and the veterinarians performing the procedures were experienced clinicians. There was also no association between rate of complication and month or season.  

Bottom line: Open standing castration may have a far higher complication rate than previously thought.

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Effects of three blood derived products on equine corneal cells, an in vitro study

J. O. Rushton, E. Kammergruber, A. Tichy, M. Egerbacher, B. Nell & S. Gabner

This prospective cohort study aimed to evaluate the potential use of platelet rich plasma (PRP) and plasma rich in growth factors (PRGF) for the treatment of corneal disease in horses. Whole blood was collected from 35 healthy horses and processed to yield serum, PRGF (using the Endoret® PRGF system) and PRP (using the E-PET™ system). The corneas from six horses deemed to have no corneal abnormalities were removed within one hour of euthanasia and processed to allow for culture of corneal limbal and stromal cells. Cells were then treated with a medium containing 20% of one of the three blood-derived products. Cell proliferation and migration were then compared amongst treatment groups in both single cell and co-culture systems.

After 48 hours of the treatment protocol, cell proliferation was seen to increase in the PRP group, remain relatively constant in the PRGF group, and decrease upon serum treatment. However, overall, there was no significant difference between the groups in relation to cell proliferation. Cell migration was significantly higher in the serum and PRP groups, and closure of a cell-free area was significantly faster in the PRP group.

Bottom Line: PRP shows promise as an aid to corneal healing in horses.

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Outcome of horses undergoing navicular bursotomy for the treatment of contaminated or septic navicular bursitis: 19 cases (2002–2016)

D.G. Suarez-Fuentes, S.S. Caston, D.M. Tatarnuik, K.D. Kersh and N.R. Ferrero

This case series evaluated the outcome of 19 horses with septic navicular bursitis that underwent navicular bursotomy. In the majority, sepsis related to penetrating foot injury. A standard surgical technique was used to remove part of the deep digital flexor tendon to expose the navicular bursa and perform sterile lavage. The wound was packed and a treatment plate fixed to the affected foot. Systemic antimicrobials were given and intravenous regional limb perfusion with antimicrobials was performed at surgery and on 2–3 occasions post-operatively. The median duration of clinical signs before surgery was 14 days, with the majority of horses affected for at least 7 days.

All horses survived to discharge from the hospital. Owners were instructed on remedial farriery in the post-operative period. Follow-up owner telephone interviews revealed 16 of 19 horses returned to their previous level of performance, with the median time to return to function being 4 months. Seven of 10 with an athletic use pre-operatively were returned to work at their previous level, with the remaining horses either returning at a lower level or retired. No horses were euthanised or required a repeat surgery.

The alternative approach of bursoscopy offers several advantages over bursotomy, including being less invasive, reduced recovery time and potentially better chances of performing at a high athletic level post-operatively. However, in chronic cases or where there are financial limitations, this case series shows that bursotomy may offer a feasible alternative, especially when concurrent regional limb perfusion and post-operative remedial farriery are employed.

Bottom line: Bursotomy coupled with regional antimicrobial perfusion and remedial farriery is an alternative to bursoscopy with sepsis of the navicular bursa. 

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Use of a saliva-based diagnostic test to identify tapeworm infection in horses in the UK

K.L. Lightbody, J.B. Matthews, J.G. Kemp-Symonds, P.A. Lambert and C.J. Austin

This retrospective longitudinal study evaluated a saliva-based test for tapeworm (Anoplocephala perfoliata) and the impact of the test on subsequent anthelmintic use. The study included 1000 saliva samples from horses at a UK welfare charity from autumn 2015 to autumn 2016. Samples were predominantly collected in autumn and spring using a commercial test (EquiSal®) that measures tapeworm-specific antibody levels in saliva samples to give a score of low, borderline, moderate or high. Horses with a score of borderline or above are considered to require anthelmintic treatment.

During the study period, 71% of horses remained below treatment threshold at all three time points and did not receive any tapeworm treatment, the remaining 29% received praziquantel on at least one occasion. Only 3% were above treatment threshold in all three tests. Younger horses required more treatments: 55% of 1- to 5-year-olds on at least one occasion and 26% on more than one occasion. Notably, 41% of new arrivals to the herd had antibody levels above treatment threshold, highlighting the importance of testing horses introduced to a herd. During the study period, 99 doses of praziquantel were administered, representing an 86% reduction in administration compared to blanket biannual use. Despite this, the prevalence of tapeworm infestation did not increase over the study period.

Bottom line: Biannual use of the saliva test may be an effective method of monitoring for tapeworm infestation and directing treatment to affected individuals, reducing selection pressure for resistance. 

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R. C. Jago, S. Scholes, T. S. Mair, G. R. Pearson, R. S. Pirie, I. Handel, E. M. Milne, F. Coyle and B. C. McGorum 

Immunolabelling with β-amyloid precursor protein, which is present in high levels in cranial cervical ganglia in equine grass sickness cases, has potential to improve the accuracy of histological examination of rectal biopsy samples. Biopsies were obtained from 21 grass sickness cases and 23 controls. In all grass sickness cases, the diagnosis was confirmed by post-mortem examination. A grading system was developed which classified the degree of immunolabelling in neurons from grade 1 (sparse labelling of neurons) to grade 3 (diffuse labelling with no unlabelled cytoplasm visible). 

Grass sickness horses had significantly lower percentage of grade 0 (normal) neurons and higher percentages of grade 1–3 neurons. Grade 3 neurons were observed in all but one grass sickness case, but were not seen in any of the control cases. When the criteria for grass sickness diagnosis was presence of at least one grade 3 neuron, this resulted in 95% sensitivity and 100% specificity. Further development of the diagnostic criteria and grading system is required before this technique can be fully applied in clinical cases. 

Bottom line: Immunolabelling for β-amyloid precursor protein in rectal biopsy samples is a promising minimally-invasive technique for ante-mortem diagnosis of equine grass sickness. 

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A. D. Haspel, S. Giguère, K. A. Hart, L. J. Berghaus and J. L. Davis 

Injectable dexamethasone may be a cost-effective alternative to other inhaled corticosteroids for long-term management of equine asthma. This randomised cross-over study set out to determine the bioavailability of injectable dexamethasone when inhaled via a nebuliser device. Dexamethasone was administered at 5 mg once daily for 5 days either intravenously or via a nebuliser in a random cross-over design, with a 3-week washout period between each administration in six healthy stabled horses. Plasma concentrations of dexamethasone was measured by liquid chromatography from samples before and at serial intervals up to 24 h after dexamethasone administration. ACTH stimulation tests were performed before the first dose and before the last dose. Bronchoalveolar lavage (BAL) was performed before the first dose and 2 hours after the last dose to provide samples for cytology. 

The mean bioavailability of nebulised dexamethasone was 4.3%. When dexamethasone was administered intravenously, a significant reduction in basal cortisol concentration was observed from Day 1 to Day 5. When the nebulised route was used there was no significant change in cortisol concentration, indicating low systemic bioavailability. For both routes of administration, the percentage of neutrophils in BAL fluid decreased significantly likely to be due to the anti-inflammatory effects of dexamethasone on the airways. 

Bottom line: Dexamethasone administered via a nebuliser has minimal systemic bioavailability and appears to reduce lower airway inflammation, therefore may provide a safe and cost-effective long- term treatment for equine asthma. Additional studies are required before it can be recommended for clinical use. 

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Assessment of horse owners’ ability to recognise equine laminitis: A cross-sectional study of 93 veterinary diagnosed cases in Great Britain

D. Pollard, C.E. Wylie, K.L.P. Verheyen and J.R. Newton

In this study, the aims were to ascertain whether owner-reported laminitis cases were confirmed as laminitis by the attending vet; and compare owner and veterinary reported information in these cases. Data were obtained from vets and owners of 93 cases of laminitis seen by 25 veterinary practices in 2014 and 2015. Respondents recorded clinical signs, risk factors and underlying disease, and owners completed their responses independently from their vets.

Welsh ponies and crosses were the most frequently represented breeds; 62% of cases were overweight. Of the 93 veterinary diagnosed cases, 51 (54.8%) were suspected to have laminitis by their owners. All 51 cases were confirmed to be laminitis by the attending vet. However, 45.2% of owners who did not suspect laminitis prior to vet diagnosis either did not know what the problem was or suspected a different condition including foot abscesses, bruised soles, navicular disease and colic.

Divergent growth rings were significantly more commonly reported by veterinary surgeons in cases where owners recognised laminitis, compared to cases unrecognised by owners. This suggests that owners of these horses either had previous experience of laminitis in their animal or used the presence of these rings as an indicator of laminitis. Difficulty in turning and weight shifting were more commonly reported by vets whereas increased hoof temperature and recumbency were more commonly reported by owners. Difficulty in turning was reported in more than 75% of cases, while the classic laminitic stance and divergent growth rings were much less common, highlighting a need to educate clients to recognise more subtle clinical signs.

Fewer owners reported equine metabolic syndrome compared to vets, but this difference was not apparent for PPID. The horse’s breed was more commonly reported as a risk factor in owner-recognised cases than in those not recognised by owners. Pony breeds were significantly more commonly reported in owner-recognised cases perhaps meaning that owners are not aware of the potential of laminitis in non-pony breeds. Fewer owners reported obesity compared to the vets, indicating that owners’ perceptions of their animal’s body condition score are not reliable.

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T. Pfau, V. Simons, N. Rombach, N. Stubbs and R. Weller

This study set out to evaluate the effects of a 4-week training programme utilising resistance bands on the equine back and core stability. Seven horses in daily ridden exercise without clinical signs of back pain were included. Inertial measurement units (IMUs) enable accurate measurement of small back movements; these were attached at the poll, withers, T16, L4–6, sacrum, left and right tuber coxae and tail base. A commercial equine resistance band system was used, which comprised an abdominal band to encourage recruitment of core abdominal muscles and a hindquarter band to increase proprioception of hindlimb movement. During Week 1 of the study the horses were acclimatised to the resistance bands and thereafter they were used for increasing periods of time each week up to 30 minutes three times a week. Normal daily exercise was reduced to compensate for the increased exercise done during band training. 

Data was collected, with and without bands in a straight line, on a left rein circle or on a right rein circle. With the bands, there was significantly less withers roll and pitch and reduced mediolateral movement in both thoracic and lumbar regions. This provides some evidence that resistance bands may aid in improving stability of the vertebral column during trot exercise. No differences occurred caudal to the lumbar region. Although the bands do not directly cause increased lumbosacral flexion, the degree of dorsoventral displacement was increased at Week 4. Further work is required to further elucidate the stabilising effects of resistance bands and assess whether these effects are due to increased activation of core musculature. 

Bottom line: A system of abdominal and hindquarter resistance bands appears to improve stability of the vertebral column in the thoracolumbar region in trot exercise. Further work is needed to further explore any benefits. 

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Equine atypical myopathy in the UK: Epidemiological characteristics of cases reported from 2011 to 2015 and factors associated with survival

S. González-Medina, J. L. Ireland, R. J. Piercy, J. R. Newton and D. M. Votion

The median age was 6 years. Middle-aged horses were more likely to survive than those <5 years. There were 60% males and 40% females and over two-thirds were in good body condition. Almost all horses (98.6%) had access to pasture, with the majority (72.5%) being turned out for 24 hours a day. In 59% of cases, the paddocks of affected horses were used for grazing all year round; this group had decreased odds of survival. Supplementary feeding was being given to 68% of horses. Horses with access to a salt lick and those receiving a vitamin or mineral supplement had significantly increased odds of survival compared to those who did not. 

In the vast majority of cases (96%), sycamore seeds were found in the paddocks; sycamore seedlings were found in 67.6% of cases. In most of these instances the sycamore trees were within, or near the paddock. The most common presenting signs were dark urine, stiffness and muscle fasciculations. For the 189 cases for which outcome was reported, 74 (38.6%) survived. 14% of cases died or were euthanased within 24 hours of onset of clinical signs. Recumbency was strongly associated with decreased odds of survival. Veterinary treatment with vitamin preparations was significantly associated with increased odds of survival. 

Bottom line: Factors associated with decreased odds of survival include full-time turnout and younger age. Vitamin/mineral supplementation in the diet and veterinary treatment including vitamin preparations were associated with increased odds of survival. 

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Preliminary investigations into novel, long-acting, injectable intramuscular formulation of omeprazole in the horse

B. W. Sykes, K. Kathawala, Y. Song, S. Garg, S. W. Page, C. Underwood and P. C. Mills

This two-part study investigated the pharmacodynamics of long-acting injectable omeprazole (LA- OMEP) and its efficacy in a pilot clinical trial. Six Thoroughbred horses on a hay-only diet were fitted with percutaneous gastrotomy tubes for continuous measurement of intra-gastric pH via an indwelling pH probe. A single 2 g intramuscular dose of LA-OMEP was administered on Day 1. Measurement of pH at two different locations within the stomach was recorded over 23 hours each day for 8 days. Good rates of ulcer healing are anticipated when intra-gastric pH is greater than 4 for at least 66% of the time. The intra-gastric pH was above 4 for 66% of the time in all horses for the first 4 days and in the majority of horses (4 out of 6) for 7 days, comparing favourably to oral omeprazole under similar conditions. 

For the pilot clinical trial, 26 horses with squamous or glandular ulceration on gastroscopic examination received a 2 g dose of LA-OMEP on Day 0 and Day 7. Repeat gastroscopy was performed 2 weeks later. Lesion healing (grade 0) was observed in all 22 cases of squamous ulceration and 75% of the nine horses with glandular ulceration. Improvement in lesion severity by at least one grade was observed in all horses in the study. A single horse developed a swelling at the site of injection that resolved without treatment. No other adverse effects were observed. 

Bottom line: Intramuscular omeprazole results in good acid suppression over a 7-day period and high rates of treatment success in clinical cases, without significant adverse effects and avoiding any issues of bioavailability associated with the oral form of omeprazole. 

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All eyes from the ERU group showed evidence of uveitis, such as lymphocytic inflammation of choroid and ciliary body, uveal haemorrhage and retinal detachment. There was no evidence of disease in the control group. 

Just over half of horses (65% ERU cases and 41% controls) were serologically positive for Leptospira, the most commonly detected serovars being bratislava, autumnalis, copenhageni and australis. There was no significant difference in serum antibody titres between the groups.  Six eyes (8%) had detectable Leptospira antibodies in the aqueous humour, all ERU cases, meaning that a positive antibody titre in aqueous humour was significantly associated with ERU. When these cases were compared with ERU cases without positive antibody titres in aqueous humour, there was no significant difference in serum antibody titres, suggesting serum antibody levels may not be helpful in differentiating Leptospira-associated ERU from other initiating causes.

Bottom line: The prevalence of Leptospira infection in ERU cases in the UK is low. Serum antibody levels do not help differentiate Leptospira-associated cases and testing of aqueous humour is required to confirm involvement of Leptospira in ERU cases. 

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Description of veterinary events and risk factors for fatality in National Hunt flat racing Thoroughbreds in Great Britain (2000-2013)

S. E. Allen, S. M. Rosanowski, A. J. Stirk and K. L. P. Verheyen

This study of 40,770 race starts aimed to evaluate veterinary events and fatalities in all National Hunt flat races. A veterinary event represented any injury or cause for the horse to be examined and/or treated by an on-course veterinary surgeon. In total 530 veterinary events were recorded i.e. 13 per 1000 starts. Fractures were the most common event, representing 23.5% of veterinary events and an incidence of 3.1 per 1000 starts. The majority (67%) involved the distal limb. Tendon and ligament injuries were the next most common event (16.4% or 2.2 per 1000 starts), with the superficial digital flexor tendon being the most commonly injured structure. In 59 veterinary events, gait abnormalities (lameness or stiffness) were recorded.

The incidence of cardiovascular problems was 0.5 per 1000 starts. Of these, vascular catastrophe accounted for 66%. The majority of respiratory events were epistaxis. Most of the 63 metabolic events related to heat exhaustion or fatigue. A fatal outcome was recorded in 117 (21.5%) of veterinary events, giving an incidence of 2.9 per 1000 starts. The majority of these were due to bony injuries, which most commonly occurred in metacarpal III or metatarsal III. Nine tendon or ligament injuries described were fatal. All fatal cardiovascular events were due to vascular catastrophe. Races restricted to conditional jockeys were more likely to have a fatality and the odds of death were higher in horses in their first race compared to those which had run before.

Bottom line: The incidence of fatalities in National Hunt flat races is 2.9 per 1000 race starts. The risk of fatality is greater in races restricted to conditional jockeys and in horses running their first race. 

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The association between exercise-induced pulmonary haemorrhage and race-day performance in Thoroughbred racehorses 

E.J. Crispe, G.D. Lester, C.J. Secombe & D.I. Perera 

This prospective observational study aimed to determine whether exercise-induced pulmonary haemorrhage (EIPH) is associated with reduced performance in racing Thoroughbreds. Over 1500 racehorses competing at three racecourses in Australia between 2012 and 2015 were included. Endoscopy was performed between 30 and 120 minutes post-race (3794 exams in total) then two clinicians blinded to the horse’s identity and race performance evaluated video recordings of these examinations. Approximately one-third of horses showed Grade 1 haemorrhage, 17% Grade 2, 5% Grade 3 and 1.2% s Grade 4. Grade 4 horses had a lower finishing position, were less likely to finish in the top three positions and collected less race earnings compared to those in the Grade 0 category. They also had a significantly slower average speed over the final 600 m and were more likely to be passed in the final 400 m. When compared to Grade 2 or less, Grade 3 and 4 horses were faster over the early sections of the race but were significantly slower over the final 600 m, more likely to decelerate over this distance and have a lower finishing position.

The findings confirm that high grades of EIPH are significantly associated with poorer performance, but there were no differences in performance in horses with none or lower grades of EIPH. The authors acknowledge many other factors that may affect individual performance.

Bottom line: Severe EIPH negatively impacts race performance. Lower grades did not affect race performance. 

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Pharmacological indices and pulmonary distribution of rifampicin after repeated oral administration in healthy foals

There was no difference in total collagen content between the three groups. At the aortic rupture site in affected Friesians collagen hydroxylation, MMP activity, elastin and collagen cross-linking were significantly higher than at the same site in unaffected horses. There were no differences in the aorta ECM between Warmbloods and unaffected Friesians. 

Collagen lysine hydroxylation was significantly lower in the DDFT of unaffected Friesians compared to Warmbloods suggesting significant differences in collagen metabolism between the two breeds. There was no difference at the DDFT site between affected and unaffected Friesians, with differences only seen at the aortic rupture site, suggesting the absence of a generalised ECM disorder in the breed. 

Bottom line: Significant remodelling has been demonstrated at the site of aortic rupture in Friesians; these changes are not present at other sites in the body or in unaffected Friesians. Potential differences in collagen metabolism between Friesians and other breeds warrant further investigation. 

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