David M. Bolt

Non-suppurative myocarditis in piglets associated with porcine parvovirus infection

The involvement of porcine parvovirus (PPV) in the aetiology of non-suppurative myocarditis in sucking piglets was investigated by a polymerase chain reaction (PCR), designed to assess the presence of viral genome in formalin-fixed paraffin wax-embedded tissue of diseased animals. Myocardium and lung of stillborn piglets with a confirmed PPV infection were used to set up the PCR amplification method. Subsequently, 20 myocardia with inflammatory lesions were examined in parallel with 20 myocardia without lesions, from age-matched control piglets. Tissues were first tested for the presence and the integrity of porcine DNA by amplifying a sequence encoding the highly conserved nuclear protein histone H4. Tissue from 15 out of 20 animals with myocarditis contained amplifiable histone H4 DNA and in 12 of the 15 histone H4-positive samples, PPV DNA was detected. It proved possible to amplify histone H4 DNA in all 20 negative controls (without myocarditis), and PPV DNA was detected in three cases. In-situ hybridization with a digoxigenin-labelled probe homologous to PPV was performed in four PCR-positive cases of non-suppurative myocarditis. In two animals several positively stained nuclei were observed in the myocardium, within or close to the mild inflammatory cellular infiltrates. These results strongly suggest that PPV can cause non-suppurative myocarditis in sucking piglets.

Anti-inflammatory and analgesic effects of intra-articular injection of triamcinolone acetonide, mepivacaine hydrochloride, or both on lipopolysaccharide-induced lameness in horses.

OBJECTIVE To assess analgesia, inflammation, potency, and duration of action associated with intra-articular injection of triamcinolone acetonide (TA), mepivacaine hydrochloride, or both in metacarpophalangeal (MCP) joints of horses with experimentally induced acute synovitis. ANIMALS 18 horses. PROCEDURES Both forelimbs of each horse were injected with lipopolysaccharide (LPS) 3 times. After the first LPS injection, 1 forelimb of each horse was treated with intra-articular injection of mepivacaine (80 mg; n=6), TA (9 mg; 6), or mepivacaine with TA (same doses of each; 6) 12 hours after the initial LPS injection. Contralateral limbs served as control limbs. Joint pain was assessed via lameness score and measurements of vertical force peak and pain-free range of motion of the MCP joint. Periarticular edema was evaluated. Degree of synovial inflammation was determined via synovial fluid analysis for WBC count and total protein concentration. Samples of plasma and synovial fluid were analyzed for TA and mepivacaine concentrations. RESULTS Each injection of LPS induced lameness and joint inflammation. Mepivacaine effectively eliminated lameness within 45 minutes after injection, regardless of whether TA was also administered, whereas TA reduced lameness, edema, and concentration of synovial fluid protein after the second LPS injection, regardless of whether mepivacaine was also injected. Treatment with TA also induced higher WBC counts and mepivacaine concentrations in synovial fluid, compared with results for mepivacaine alone. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested TA is a potent analgesic and anti-inflammatory medication for acute synovitis in horses and that simultaneous administration of mepivacaine does not alter the potency or duration of action of TA.

Effects of triamcinolone acetonide, sodium hyaluronate, amikacin sulfate, and mepivacaine hydrochloride, alone and in combination, on morphology and matrix composition of lipopolysaccharide-challenged and unchallenged equine articular cartilage explants.

OBJECTIVE To evaluate the effects of triamcinolone acetonide (TA), sodium hyaluronate (HA), amikacin sulfate (AS), and mepivacaine hydrochloride (MC) on articular cartilage morphology and matrix composition in lipopolysaccharide (LPS)-challenged and unchallenged equine articular cartilage explants. SAMPLE POPULATION 96 articular cartilage explants from 4 femoropatellar joints of 2 adult horses. PROCEDURES Articular cartilage explants were challenged with LPS (100 ng/mL) or unchallenged for 48 hours, then treated with TA, HA, AS, and MC alone or in combination for 96 hours or left untreated. Cartilage extracts were analyzed for glycosaminoglycan (GAG) content by dimethyl-methylene blue assay (ng/mg of dry wt). Histomorphometric quantification of total lacunae, empty lacunae, and lacunae with pyknotic nuclei was recorded for superficial, middle, and deep cartilage zones. RESULTS LPS induced a significant increase in pyknotic nuclei and empty lacunae. Treatment with TA or HA significantly decreased empty lacunae (TA and HA), compared with groups without TA or HA, and significantly decreased empty lacunae of LPS-challenged explants, compared with untreated explants. Treatment with AS or MC significantly increased empty lacunae in unchallenged explants, and these effects were attenuated by TA. Treatment with MC significantly increased empty lacunae and pyknotic nuclei and, in combination with LPS, could not be attenuated by TA. Content of GAG did not differ between unchallenged and LPS-challenged explants or among treatments. CONCLUSIONS AND CLINICAL RELEVANCE Treatment with TA or HA supported chondrocyte morphology in culture and protected chondrocytes from toxic effects exerted by LPS, AS, and MC.

Identifying optimal parameters for quantification of changes in pelvic movement symmetry as a response to diagnostic analgesia in the hindlimbs of horses

REASONS FOR PERFORMING STUDY Subjective evaluation of the response to diagnostic analgesia of hindlimb lameness is influenced by expectation bias. Quantification of pelvic movement with inertial measurement units is possible, but it is unclear which measure of movement symmetry best reflects the changes seen after diagnostic analgesia. OBJECTIVES To test our hypothesis that objective measures closely relating to those used for subjective visual lameness scoring (quantifying the difference between sacral upward or downward movement or between movement amplitudes of the left and right tubera coxae) would show the largest and most consistent response. STUDY DESIGN Retrospective analysis of subjective and objective clinical lameness data. METHODS Thirteen horses with hindlimb lameness underwent visual lameness scoring and independent gait assessment with inertial measurement units. Established objective measures were calculated and changes before/after diagnostic analgesia regressed against the change in lameness grade. Slopes of regression lines were calculated and confidence intervals assessed. RESULTS All objective parameters showed variation between horses and across lameness grades. The following 3 measures documented a consistent increase in symmetry for each grade of change in lameness score: difference between sacral displacement minima; upward movement difference; and range of motion difference between the tubera coxae. CONCLUSIONS Several pelvic parameters are suitable for objective quantification of changes after diagnostic analgesia in hindlimb-lame horses. A change of 9-13% per lameness grade can be expected. Upward movement of the tubera coxae is the most sensitive objective measure for quantifying a response to diagnostic analgesia. However, when assessed visually, this measure requires simultaneous focusing on pelvic and limb movements. Other parameters that show a similar response might be more easily perceived, requiring only assessment of tubera coxae range of motion or downward displacement of the sacrum without simultaneous focus on limb movement.

Stimulus-dependent release of tissue-regenerating factors by equine platelets.

REASONS FOR PERFORMING THE STUDY Platelet-rich plasma (PRP) is increasingly used for treatment of orthopaedic injuries. However, the effects of different stimuli on the release pattern of regenerative and proinflammatory factors from equine platelets are largely unknown and an optimal treatment protocol remains to be established. OBJECTIVES The aim of this study was to identify a stimulus that enhanced release of histopromotive factors (platelet-derived growth factor BB [PDGF] and transforming growth factor 1β[TGF]) without causing concurrent release of a proinflammatory mediator (CCL5). METHODS Washed platelets were prepared from 6 healthy ponies and release of growth factors and CCL5 measured using commercially available ELISAs for human proteins following incubation with or without thrombin, chitosan or equine recombinant tumour necrosis factor (erTNF) over 24 h and subsequently over 96 h. Additionally, noncoagulated samples were analysed. RESULTS Regardless of whether a stimulus was present or what stimulus was used, PDGF and TGF release was maximal by 0.5-1 h when clot formation took place and very little release was observed after 24 h. Growth factor release was minimal in noncoagulated samples. In contrast, CCL5 release was not associated with coagulation and appeared to persist for much longer. High concentrations of erTNF caused significantly greater release of CCL5 at 6 h than any other stimulus tested. CONCLUSIONS Growth factor release from equine platelets is dependent on coagulation but independent of the initiating stimulus, and is accompanied by more sustained release of proinflammatory mediators. POTENTIAL RELEVANCE Supernatants collected from coagulated platelets could be an alternative treatment to PRP.

Variation in foot conformation in lame horses with different foot lesions

Foot conformation in the horse is commonly thought to be associated with lameness but scientific evidence is scarce although it has been shown in biomechanical studies that foot conformation does influence the forces acting on the deep digital flexor tendon (DDFT) and the navicular bone (NB). The aim of this study was to determine the relationships between foot conformation and different types of lesion within the foot in lame horses. It was hypothesised that certain conformation parameters differ significantly between different types of foot lesions. Conformation parameters were measured on magnetic resonance images in the mid-sagittal plane of 179 lame horses with lesions of their deep digital flexor tendon (DDFT), navicular bone (NB), collateral ligaments of the distal interphalangeal joints and other structures. Conformation parameters differed significantly between lesion groups. A larger sole angle was associated with combined DDFT and NB lesions, but not with NB lesions alone. A more acute angle of the DDFT round the NB was associated with DDFT and NB lesions, and a lower heel height index with DDFT injury. The larger the sole angle the smaller the likelihood of a DDFT or NB lesion with odds ratios of 0.86 and 0.90, respectively. This study shows an association between foot conformation and lesions but it does not allow the identification of conformation as causative factor since foot conformation may change as a consequence of lameness. Future studies will investigate foot-surface interaction in lame vs. sound horses, which may open a preventative and/or therapeutic window in foot lame horses.

Indications, complications, and outcome of horses undergoing repeated celiotomy within 14 days after the first colic surgery: 95 cases (2005-2013)

OBJECTIVE To examine factors associated with short- and long-term prognosis for horses undergoing repeated celiotomy within 14 days after the first colic surgery. DESIGN Retrospective case series. ANIMALS 95 horses that had undergone 2 celiotomies within a 14-day period between 2005 and 2013 at 3 equine referral hospitals. PROCEDURES Historical, clinical, and laboratory data were compared between horses that did not survive and horses that did survive to hospital discharge (short-term survival rate) and to > 3 and > 6 months after hospital discharge (long-term survival rates). RESULTS Strangulating small intestinal lesions were the most common finding during the first celiotomy (60/95 [63.2%]), and persistent gastric reflux was the most common reason for the second celiotomy (56/95 [58.9%]). Reasons for a second celiotomy were not associated with survival rate. For horses that had long-term follow-up, 22 of 92 (23.9%) survived > 6 months after hospital discharge. Two of 13 horses with intestinal resections during both surgeries survived to > 6 months after hospital discharge. Compared with horses not undergoing intestinal resection, significantly fewer horses requiring resection during 1 or both surgeries survived to hospital discharge and to > 3 and > 6 months after hospital discharge. Incisional infections occurred in 68.4% (26/38) of horses that survived to hospital discharge, and 31.6% (12/38) developed incisional hernias or dehiscence. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that the prognosis for horses undergoing repeated celiotomy is guarded, and intestinal resection negatively affects the long-term survival rate.

Persistent penile erection (priapism) after acepromazine premedication in a gelding.

There are very few reported cases of equine priapism after acepromazine administration in the veterinary literature despite well-documented warnings in textbooks and drug company datasheets. Indeed, Driessen et al. (2010) found the actual prevalence of equine priapism to be <1 case in 10,000 where acepromazine is used. We wish to report a case of priapism in a 19 year-old, 519 kg Arab-cross gelding that was anaesthetized for a repair of a laceration to the right upper eyelid. The owner reported no current health issues and a clinical examination revealed no abnormalities. Acepromazine (Novartis, UK) 0.04 mg kg was administered intramuscularly (IM) and the penis became erect within approximately 5 minutes and could not be manually reduced into the prepuce: the horse was monitored but did not retract the penis during the 90-minute premedication period. Procaine penicillin, (Norocillin; Norbrook Pharmaceuticals, UK), 22,000 IU kg IM, and phenylbutazone, (Equipalazone; Dechra Veterinary Products Ltd, UK), 4.4 mg kg slowly intravenously (IV), were administered to the horse prior to sedation with 15 lg kg IV of detomidine (Domosedan; Janssen Animal Health, UK). The penis, which could still not be manually reduced into the prepuce, was bandaged against the ventral abdomen. Anaesthesia was induced with 2.2 mg kg ketamine (Ketaset; Pfizer Limited, UK) and 0.02 mg kg diazepam (Diazepam Injection; Hameln Pharmaceuticals, UK) IV and was maintained with isoflurane (IsoFlo; Abbott, UK) vaporized in oxygen via a large animal anaesthetic machine and was uneventful. Reduction of the penis into the prepuce under anaesthesia was unsuccessful. A urinary catheter was placed into the urethra (Fig. 1) and an Esmarch bandage placed tightly around the penis from the glans, proximally, to attempt exsanguination. After 25 minutes, the Esmarch bandage was removed and the now flaccid penis was manually reduced into the prepuce, which was sutured closed prior to anaesthetic recovery (Fig. 2). The retaining suture was removed from the prepuce 30-minutes after an

Diagnosis, Management, and Outcome in 19 Horses with Deltoid Tuberosity Fractures

OBJECTIVE To describe the diagnosis and treatment of fractures of the deltoid tuberosity. STUDY DESIGN Case series. METHODS Medical records (1992-2009) of 19 horses with radiographic confirmation of deltoid tuberosity fractures were reviewed. Data retrieved included signalment, clinical and diagnostic imaging findings, and treatment. Outcome was determined by telephone questionnaire of owners and referring veterinarians. RESULTS Most horses were markedly lame on admission and 53% had reduced protraction of the affected limb. All fractures were identified on a cranio45° medial-caudolateral oblique projection; however, only 32% (6 horses) were detected on a mediolateral projection whereas 86% were evident ultrasonographically. Treatment by local wound care and stall rest resulted in return to athletic function without lameness for 13 of 14 horses that had follow-up. CONCLUSIONS A cranio45° medial-caudolateral oblique radiographic view was better than a mediolateral projection for identification of deltoid tuberosity fractures. Ultrasonographic detection of fractures was similar except when gas accumulation obscured the fracture site. Deltoid tuberosity fractures can cause severe lameness but can be treated successfully with conservative management.

Forces applied with a hoof tester to cadaver feet vary widely between users

Hoof testers are commonly used in equine practice. In this study, we determined the intraoperator and interoperator reliability of force application with hoof testers for different groups: experienced veterinarians, novices and farriers. For this purpose, we have developed and validated an instrumented hoof tester. Forces varied significantly between the different regions of the foot for experienced operators applying the highest forces to the heels, then the frog, then the toe, and the lowest forces to the quarters. Novices applied significantly more force to the toe versus the frog. Intraoperator reliability varied significantly between regions and operators. Novices had the narrowest width of limits of agreement for the frog and heel, but the widest for the toe and the quarters, whereas farriers had the narrowest width of agreement for the toe and quarter. Force application differed significantly between groups for the frog and heel regions, but not the toe and quarters. Veterinarians applied higher forces to the frog compared with farriers and novices, and higher forces to the heel compared with novices. This study showed that hoof tester forces vary widely within and between operators, and standardisation of hoof tester use is needed to make this diagnostic test more reliable.