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Summary A Percheron mare was presented for acute, severe lameness and marked swelling of the right forelimb after being cast. The mare was initially diagnosed with cellulitis of the forelimb but as her condition improved and the affected limb was able to bear more weight it became apparent that the limb was hyperextended at the level of the carpus. Widening of the palmar aspect of the middle carpal joint was observed radiographically. During ultrasonographic examination, excessive fluid in the carpal sheath and perithecal swelling were noted and tearing of the palmar carpal ligament was suspected. A dynamic brace was fabricated to prevent hyperextension of the carpus. After discontinuation of systemic antibiotics, the mare became febrile and forelimb lameness worsened. Cytology of fluid from the middle carpal joint confirmed joint sepsis and the mare was anaesthetised for arthroscopic examination. A tear in the palmar carpal ligament, characterised by focal fibre disruption and fibrillation, was identified during arthroscopic and tenoscopic examination. Communication between the carpal flexor tendon sheath and middle carpal joint was identified during these procedures. Both the middle carpal joint and carpal flexor tendon sheath were lavaged with physiological saline solution. Post operatively, swelling and lameness slowly resolved. Four months after discharge, the mare was sufficiently sound to be maintained at pasture. Viewed from its lateral aspect, the limb no longer appeared to be hyperextended from the carpus.

Objective To assess outcome after neurectomy of the deep branch of the lateral palmar nerve (DBLPaN) as a treatment for horses with persistent lameness associated with chronic proximal suspensory desmitis (PSD) of the thoracic limb. Study Design Case series. Animals Adult, mixed-breed horses (n = 4), weighing 510–585 kg, used for amateur show-jumping. Methods Records of 4 horses chronically lame because of PSD of one or both thoracic limbs that were treated by neurectomy of the DBLPaN were reviewed. The site of pain causing lameness was localized using regional anesthesia. The proximal aspect of the suspensory ligament of the affected limb(s) of all horses were enlarged on ultrasonographic examination, but fiber disruption was not observed. All horses remained lame after conservative therapy. Neurectomy was performed with the horses anesthetized and positioned in dorsal recumbency. Results All 4 horses were sound at 6 weeks and remained sound for at least 12 months after neurectomy. Conclusion Lameness in horses caused by chronic PSD can be resolved by neurectomy of the DBLPaN in horses that are refractory to conservative management.

Reproductive surgical techniques are considered by practitioners/clinicians of theriogenology to be the most beneficial reproductive management that can be performed to treat conditions of cows that may affect fertility. Conditions affecting the reproductive tract can cause pathologic changes that may result in substantial economic and genetic losses to beef and dairy producers. Some injuries and diseases are amenable to surgical treatment. Surgical restoration of fertility preserves genetic potential and economic productivity. The surgical procedures described in this article are some of the most commonly used to restore fertility in cows with injury or diseases affecting their reproductive tracts.

Transplantation of mesenchymal stromal cells (MSCs) to sites of experimentally-created nerve injury in laboratory animals has shown promising results in restoring nerve function. This approach for nerve regeneration has not been reported in horses. In this study, we first evaluated the in vitro ability of equine, bone marrow-derived MSCs (EBM-MSCs) to trans-differentiate into Schwann-like cells (SLCs) and subsequently tested the MSCs, in vivo for their potential to regenerate a transected nerve after implantation. The EBM-MSCs from 3 equine donors were differentiated into SCLs for 7 days, in vitro, in the presence of specialized differentiation medium and evaluated for morphological characteristics, by using confocal microscopy, and for protein characteristics, by using selected Schwann-cell markers (GFAP and S100b). The EBM-MSCs were then implanted into the fascia surrounding the ramus communicans of one fore limb of 3 healthy horses after a portion of this nerve was excised. The excised portion of the nerve was examined histologically at the time of transection, and stumps of the nerve were examined histologically at day 45 after transplantation. The EBM-MSCs from all donors demonstrated morphological and protein characteristics of those of Schwann cells 7 days after differentiation. Nerves implanted with EBM-MSCs after nerve transection did not show evidence of nerve regeneration at day 45. Examination of peripheral nerves collected 45 days after injury and stem cell treatment revealed no histological differences between nerves treated with MSCs and those treated with isotonic saline solution (controls). The optimal delivery of MSCs and the model suitable to study the efficacy of MSCs in nerve regeneration should be investigated.

Mesenchymal stromal cells (MSCs) have the capacity to differentiate into cells of mesenchymal lineage, such as chondrocytes, and have potential for use in regeneration of equine articular cartilage. MSCs instilled intra-articularly would be exposed to the inflamed environment associated with equine osteoarthritis (OA), which may compromise their function and ability to heal a cartilaginous defect. The aim of this study was to assess the ability of equine adult MSCs to differentiate into chondrocytes when stimulated with pro-inflammatory cytokines. MSCs derived from equine bone marrow (BM) and from synovial fluid (SF) were cultured in chondrogenic induction medium containing transforming growth factor (TGF)-β1. BM-derived MSCs (BMMSCs) and SF-derived MSCs (SFMSCs) were stimulated with 100 ng/mL interferon (IFN)-γ and 10 ng/mL tumor necrosis factor (TNF)-α. Chondrogenic differentiation was measured quantitatively with the glycosaminoglycan (GAG) assay and qualitatively by immunofluorescence (IF) for SOX-9, TGF-β1, aggrecan and collagen II. The viability of equine MSCs was maintained in the presence of IFN-γ and TNF-α, but production of GAGs from both types of MSCs was decreased in stimulated medium. Exposure of BMMSCs to pro-inflammatory cytokines reduced the levels of SOX-9, TGF-β1, aggrecan and collagen II, whereas exposure of SFMSCs to these cytokines reduced the levels of aggrecan only. These data suggest that pro-inflammatory cytokines do not affect proliferation of MSCs, but could inhibit chondrogenesis of MSCs.

Summary This report describes the treatment of an aged mare for bilateral, branchial remnant cysts by marsupialisation and sclerotherapy the cysts. Treatment to resolve the cysts was prolonged, but the mare had no long-term complications.

†‡ Summary Reasons for performing study: Clinical experiences indicate that centesis of the lateral compartment of the femorotibial joint is often unsuccessful. Objective: To determine the accuracy of 2 published and 2 unpublished techniques of centesis of the lateral compartment of the femorotibial joint. Hypothesis: It was hypothesised that a drug can be administered into the lateral compartment of the femorotibial joint via a diverticulum of this joint that surrounds the medial aspect of the long digital extensor tendon and that this technique is more accurate than described techniques of centesis of this compartment. Methods: Twenty-four stifles of 12 horses were divided equally into 4 groups and a radiocontrast medium injected into the lateral compartment of the femorotibial joint of each group using a hypodermic needle inserted: 1) caudal to the lateral patellar ligament and proximal to the tibial plateau, 2) caudal to the long digital extensor tendon and proximal to the tibial plateau, 3) between the long digital extensor tendon and bone of the extensor groove of the tibia or 4) directly through the long digital extensor tendon until it contacted bone. Twelve veterinary students who had no experience using any of these techniques performed the injections. Accuracy of each technique was determined by examining radiographs obtained after injecting the contrast medium. Results: The most successful technique for arthrocentesis was by inserting a needle through the long digital extensor tendon. This approach was successful in all attempted cases, whilst other techniques had lower rates of success. Conclusions: The lateral compartment of the femorotibial joint can be accessed accurately by inserting a needle through the long digital extensor tendon as it lies within the extensor groove. Other techniques may not be as accurate for clinicians inexperienced in arthrocentesis of the lateral compartmen to f the femorotibial joint.

Objective: To describe the anatomic features of the equine trochanteric bursa and to evaluate 4 techniques for bursa centesis. Study Design: Prospective, randomized design. Animals: Equine cadavers (n=2) and 20 live horses. Methods: The trochanteric bursae of 2 equine cadavers were injected with latex to identify the boundaries of the bursae. Four techniques for centesis of the trochanteric bursa were evaluated by attempting to inject dye into both trochanteric bursae of 20 live horses. Techniques included injection of the bursa with the limb-bearing weight and injection with the limb nonweight bearing and supported on a block, with or without ultrasonographic guidance of the needle. Ultrasonographic guidance of the needle was performed with or without the use of a guide channel attached to the ultrasound probe. Each of the 4 techniques was used to inject 10 bursae. The region of the bursa was dissected after horses were euthanatized to determine the location of the dye. Results: The trochanteric bursa was most successfully injected with the limb positioned caudally with the foot on a block, even though topographic landmarks for centesis were more difficult to identify when the limb was in this position. The highest incidence of success was achieved when the needle was inserted using ultrasonographic guidance with the foot in a Hickman block. Conclusion: Positioning the limb caudally with the foot nonweight bearing and on a block facilitated centesis of the trochanteric bursa.

Summary A sinocutaneous or nasocutaneous fistula is usually a sequel to a comminuted fracture of one or more facial bones, whereas an oronasal or oromaxillary sinus fistula occurs most commonly after a maxillary alveolus fails to fill with healthy granulation tissue after its tooth has been lost. Horses with a sinocutaneous or nasocutaneous fistula can be treated by covering the fistula with transposed muscle, which in turn is covered by adjacent skin or a free skin graft, or by covering the fistula with periosteum transposed from adjacent bone, itself covered by adjacent skin or left uncovered to heal by second intention. Horses with an oronasal or oromaxillary sinus fistula can usually be treated successfully by temporarily occluding the oral aspect of the fistula, to prevent feed from entering the fistula, until the apical end of the alveolus fills with healthy tissue. Other methods of treatment include covering the oral aspect of the fistula with a mucoperiosteal flap or filling the fistula with a transposed facial muscle.

Objective: To determine whether ventriculocordectomy (VCE) performed before prosthetic laryngoplasty (PL) results in increased rima glottidis size compared with PL alone. Study Design: Experimental study. Animals: Equine cadaver larynges (n=13). Methods: Right arytenoid cartilages were maximally abducted using a standard PL technique. Standard PLs were then performed on the left side and the force required to maximally abduct the left arytenoid cartilage recorded (Fmax). Photographs were taken of the rima glottidis at zero force and at five equal levels of force up to Fmax. The force applied was released, left VCE performed, and photographs repeated. Arytenoid left:right angle quotients (LRQ) and glottic cross-sectional area ratios (CSAR) were calculated at each force level in each condition (PL and VCE-PL). Results: Mean LRQ and CSAR for both PL and VCE-PL increased with increasing force, initially rapidly before plateauing at ∼50% of Fmax. LRQ and CSAR were significantly greater for VCE-PL than for PL (P

Objective: To describe successful surgical treatment of urinary incontinence caused by a ruptured and/or transected urethral sphincter in a mare. Study Design: Clinical report. Animal: A 7-year-old, Swedish Warmblood mare with urinary incontinence. Methods: The urethral sphincter, which had been damaged during removal of a cystic urolith, was repaired by apposing the ends of the disrupted urethralis muscle and tunica muscularis. Results: The mare was no longer incontinent after repair of the defect by apposition of the ends of the urethralis muscle and tunica muscularis. Conclusions: Transection and/or rupture of the urethral sphincter of a mare may result in urinary incontinence. Clinical Relevance: Apposition of the ends of the ruptured or transected urethralis muscle and tunica muscularis can correct urinary incontinence caused by this defect.

Objective: To report clinical signs and management of hypospadias in a horse. Study Design: Clinical report. Animal: A 6-year-old, Friesian gelding. Methods: Partial phallectomy was performed to resolve contact dermatitis of the pelvic limbs and abnormal behavior during urination. Subsequent urethral meatal stenosis was treated by revision. Results: Hypospadias and chordee caused altered direction of urine flow, contact dermatitis of the pelvic limbs, and abnormal behavior. Partial phallectomy and subsequent revision after meatal stenosis resolved urine direction, flow and abnormal behavior. Conclusions: Abnormalities of the urinary tract associated with hypospadias can result in urine-induced, contact dermatitis and distress during urination, but these complications can be resolved by partial phallectomy.

Summary Reasons for performing study: No studies have determined the pharmacokinetics of low-dose amikacin in the mature horse. Objectives: To determine if a single i.v. dose of amikacin (10 mg/kg bwt) will reach therapeutic concentrations in plasma, synovial, peritoneal and interstitial fluid of mature horses (n = 6). Methods: Drug concentrations of amikacin were measured across time in mature horses (n = 6); plasma, synovial, peritoneal and interstitial fluid were collected after a single i.v. dose of amikacin (10 mg/kg bwt). Results: The mean ± s.d. of selected parameters were: extrapolated plasma concentration of amikacin at time zero 144 ± 21.8 µg/ml; extrapolated plasma concentration for the elimination phase 67.8 ± 7.44 µg/ml, area under the curve 139 ± 34.0 µg*h/ml, elimination half-life 1.34 ± 0.408 h, total body clearance 1.25 ± 0.281 ml/min/kg bwt; and mean residence time (MRT) 1.81 ± 0.561 h. At 24 h, the plasma concentration of amikacin for all horses was below the minimum detectable concentration for the assay. Selected parameters in synovial and peritoneal fluid were maximum concentration (Cmax) 19.7 ± 7.14 µg/ml and 21.4 ± 4.39 µg/ml and time to maximum concentration 65 ± 12.2 min and 115 ± 12.2 min, respectively. Amikacin in the interstitial fluid reached a mean peak concentration of 12.7 ± 5.34 µg/ml and after 24 h the mean concentration was 3.31 ± 1.69 µg/ml. Based on a minimal inhibitory concentration (MIC) of 4 µg/ml, the mean Cmax : MIC ratio was 16.9 ± 1.80 in plasma, 4.95 ± 1.78 in synovial fluid, 5.36 ± 1.10 in peritoneal fluid and 3.18 ± 1.33 in interstitial fluid. Conclusions: Amikacin dosed at 10 mg/kg bwt i.v. once a day in mature horses is anticipated to be effective for treatment of infection caused by most Gram-negative bacteria. Potential relevance: Low dose amikacin (10 mg/kg bwt) administered once a day in mature horses may be efficacious against susceptible microorganisms.

Lymphocytic-plasmacytic enteritis (LPE) is a morphological diagnosis given to a type of infiltrative intestinal disease classified within the complex of idiopathic inflammatory bowel disease (IBD). The purpose of this retrospective study was to describe the details of breed, age and sex, clinical and clinicopathological findings and outcome of horses diagnosed with LPE. Data were reported from 14 horses that had a histopathological diagnosis of LPE; the median age was 12 years, and there was no breed or sex predilection. Common clinical signs were weight loss (100%), diarrhoea (50%) and lethargy (50%). Hypoproteinaemia and hypoalbuminaemia were present in 6/13 (46%) and 9/12 (75%) horses, respectively. Results of the oral glucose tolerance tests or D-xylose absorption tests were abnormal in 9/12 (75%) horses and rectal mucosal biopsies were abnormal in 3/7 (43%) horses. Corticosteroid treatment was used unsuccessfully in 4 horses. All horses were subjected to euthanasia and LPE was diagnosed at necropsy. Diffuse thickening of the small intestine was apparent grossly in 10/13 (77%) horses examined. LPE is an uncommon equine intestinal disease that is difficult to diagnose antemortem and has a poor prognosis.

Summary Analgesia usually occurs within 5 min after administration of local anaesthetic solution into joints or around nerves in the distal portion of the limb. Gait should be assessed within 10 min after diagnostic regional analgesia of the distal portion of the limb because rapid diffusion of anaesthetic solution can result in anaesthesia of other nerve branches, thus confusing results of the examination. A palmar digital nerve block (PDNB) anaesthetises most of the foot, including the distal interphalangeal (DIP) joint (coffin joint), rather than just the palmar half of the foot, as was once commonly believed. To avoid partially anaesthetising the proximal interphalangeal joint (pastern joint), the palmar digital nerves should be anaesthetised near or distal to the proximal margin of the collateral cartilages. Clinicians should be aware that an abaxial sesamoid nerve block (ASNB) may ameliorate or abolish pain within the metacarpo/metatarso-phalangeal joint (fetlock joint). Mepivacaine administered into the DIP joint desensitises the DIP joint and probably the palmar digital nerves to also cause anaesthesia of the navicular bursa, the navicular bone, the toe region of the sole, the digital portion of the deep digital flexor tendon (DDFT) and the distal portions of the collateral ligaments of the DIP joint. When a large volume of mepivacaine HCl (e.g. 10 ml) is administered, the heel region of the sole may also be desensitised. Only a small percentage of horses with disease of the collateral ligament(s) of the DIP joint show a significant improvement in lameness after intra-articular analgesia of the DIP joint, and no horse is likely to improve after intrabursal analgesia of the navicular bursa. A PDNB, however, improves lameness substantially in most horses that are lame because of disease of the collateral ligament(s) of the DIP joint, and all affected horses are likely to become sound after an abaxial sesamoid nerve block. The degree of improvement in lameness associated with injury to one or both collateral ligaments of the DIP joint after PDNB is determined by the extent of the injury and the level at which the palmar digital nerves are anaesthetised. The further proximal the level of the injury within the collateral ligament, the less likely that lameness is ameliorated by analgesia of the DIP joint or a PDNB. Verschooten's technique appears to be the most accurate technique for centesis of the navicular bursa. Even though analgesia of the DIP joint results in analgesia of the navicular bursa, analgesia of the navicular bursa does not result in analgesia of the DIP joint. Pain arising from the DIP joint can probably be excluded as a cause of lameness when lameness is attenuated by analgesia of the navicular bursa. Analgesia of the digital flexor tendon sheath (DFTS) is likely to desensitise only structures that are contained within or border on the sheath itself (i.e. the superficial and deep digital flexor tendons, the straight and oblique distal sesamoidean ligaments, the annular ligaments of the fetlock and pastern, and the portion of the DDFT that lies within the foot). Because lameness caused by disease of the DDFT within the foot may fail to improve appreciably after analgesia of the palmar digital nerves, the DIP joint, or the navicular bursa, a portion of the DDFT within the foot and distal to the DFTS probably receives its sensory supply from more proximal deep branches of the medial and lateral palmar digital nerves that enter the DFTS. Performing intrathecal analgesia of the DFTS on horses with lameness that is unchanged after anaesthesia of the palmar digital nerves but resolves after an ASNB, may be useful in localising lameness to that portion of the DDFT that lies within the foot. Resolution of lameness after intrathecal analgesia of the DFTS justifies suspicion of a lesion within the digital portion of the DDFT or within structures contained within the DFTS. The belief that concurrent or sequential intra-articular administration of medication substantially increases the risk of joint infection or that inflammation caused by the local anaesthetic solution may dampen the therapeutic response to intra-articular medication appears to be unfounded.

Summary A 4-year-old, Spanish Mustang mare was evaluated because of a swelling on the dorsolateral aspect of its right carpus. The horse had no gait abnormalities. During radiographic examination of the carpus, a granular, radiopaque mass, approximately 3 cm in diameter, adjacent to the proximal row of carpal bones, was observed. The mineralised mass, which was located within the antebrachiocarpal joint, was removed through an arthrotomy with the horse anaesthetised. Histological features of the mass showed it to be overlain by partially denuded synovium, and included large deposits of mineral surrounded by multinucleated giant cells and separated by septa of mature fibrous connective tissue. These features were typical of calcinosis circumscripta. Swelling of the carpus resolved after the surgery, but the horse was lost to follow-up.

Summary A cyst filled with fluid was found to be the cause of an enlarged antebrachium in a horse. Communication between the cyst and the elbow joint was demonstrated by: 1) finding, during radiographic examination of the elbow, radiopaque contrast solution instilled into elbow joint within the cyst; 2) finding cytological values in fluid aspirated from the cyst that were similar to those in fluid aspirated from the elbow joint; and 3) finding hyperechoic foci, assumed to be air bubbles, during ultrasonographic examination of the cyst after administration of air into the elbow joint. Communication of the cyst with the elbow joint was confirmed during post mortem examination of the affected limb.

Case Description—A 12-year-old 500-kg (1,100-lb) American Quarter Horse mare was evaluated because of chronic mucopurulent, bloody discharge from the left nostril, inspiratory dyspnea, and respiratory noise. Clinical Findings—The horse had severe inspiratory dyspnea and stertorous respiration with no airflow from the left nostril. A temporary tracheostomy was performed. Endoscopy revealed a tan mass protruding from the left middle nasal meatus into the left common nasal meatus; it extended caudally into the nasopharynx and around the caudal edge of the nasal septum into the right nasal cavity. Radiographically, a soft tissue opacity was evident in most of the left nasal cavity and left paranasal sinuses. Cytologic examination of mass tissue revealed evidence of pyogranulomatous rhinitis; thickly encapsulated, budding yeast typical of Cryptococcus neoformans were detected. Treatment and Outcome—While the horse was sedated and in a standing position, the fungal granuloma was removed from the paranasal sinuses. Treatment with fluconazole (5 mg/kg [2.27 mg/lb], PO, q 24 h for 4 weeks) was initiated; enilconazole (50 mL of a 10% solution) was instilled into the paranasal sinuses every other day (7 lavages). Six weeks after surgery, infection had not recurred and epithelialization appeared normal in the left paranasal sinuses. Clinical Relevance—In horses with cryptococcosis of the paranasal sinuses, surgical removal of granulomatous lesions and systemic and topical administrations of antifungal drugs may be curative. Successful surgery may be performed in standing horses. Concommitant removal of a large portion of the conchae allows follow-up rhinoscopic evaluation of the paranasal sinuses.

Summary Moxidectin has broad-spectrum anti-nematodal and anti-arthropodal activities in the horse but is not effective against tapeworms or flukes. Moxidectin and ivermectin have the same efficacy against internal, adult parasites of horses. Moxidectin, however, is highly effective in eliminating encysted and hypobiotic larval stages of cyathostomins, whereas ivermectin is not. Treatment of horses with moxidectin results in an egg-reappearance period (ERP) of 15–24 weeks. Because of its long ERP, moxidectin is labelled to be used at 12 week intervals. Moxidectin may provide protection against infection by ingested cyathostomin larvae for 2–3 weeks after it is administered. The larvicidal activity of moxidectin has often been compared to that of fenbendazole administered at either 7.5 or 10 mg/kg bwt for 5 consecutive days. The efficacy of fenbendazole, when administered daily for 5 consecutive days at 7.5 or 10 mg/kg bwt, against all stages of cyathostomins is often less than that of moxidectin because resistance of cyathostomins to benzimidazoles is prevalent worldwide, and the 5 day course of fenbendazole does not overcome this resistance. There are now reports of resistance of ascarids to moxidectin. Overt resistance of cyathostomins and a shortened egg re-emergence period after treatment with moxidectin have been reported. Rapid removal of manure by natural fauna can significantly reduce larval nematode concentrations and thereby reduce intervals of anthelmintic treatment. Of the macrocyclic lactones, moxidectin has the least deleterious effect on faecal fauna.

Objective— To describe pathologic changes in the deep branch of the lateral plantar nerve (DBLPN) of horses determined to be lame because of proximal suspensory desmitis (PSD), and to report the outcome after treatment by excision of a segment of the horses' DBLPN. Study Design— Retrospective case series. Animals— Adult horses (n=16). Methods— Horses determined to be lame on one or both pelvic limbs because of PSD were treated by excision of a segment of the DBLPN, and 30 nerves were examined histologically. Owners were contacted to obtain information about the horses ≥6 months after surgery. Results— Histologic changes suggestive of chronic nerve compression were identified in both nerves of 11 bilaterally lame horses and in the lame limb of 5 unilaterally lame horses. The nerve of the sound limb of 2 of 3 unilaterally lame horses that had bilateral nerve resection also had histologic changes compatible with nerve compression. Ten of 16 horses (62.5%) with follow-up information returned to soundness after excision of the DBLPN. Conclusions— Pathologic changes of the DBLPN associated with compression may complicate PSD of the pelvic limbs. Excision of the nerve may resolve lameness caused by PSD. Clinical Relevance— Horses lame because of PSD of the pelvic limb may remain lame after desmitis has resolved because of compression of the DBLPN. Excising a portion of this nerve may resolve lameness.

Objective: To describe surgical techniques used for correction of congenital nasal deviation (wry nose) in horses (wry nose) and to report outcome. Study design: Retrospective study. Animals: Horses (n=4), 5-17 months old with wry nose. Methods: Nasal deviation was corrected by transecting the premaxillae/maxillae and nasal bones at their site of maximum curvature and realigning and stabilizing the bones in a more normal alignment using internal fixation. The nasal septum was removed during the same anesthetic period. Results: For each horse, physical appearance was improved and respiratory stridor eliminated. Conclusions: Wry nose can be corrected by transecting the premaxillae/maxillae and nasal bones and stabilizing the transected bones in a more normal alignment; the nasal septum can be removed concurrently. Clinical relevance: Surgical correction of wry nose may provide a good functional and cosmetic outcome.

Objective—To determine the effects of hyperbaric oxygen therapy (HBOT) on full-thickness skin grafts applied to fresh and granulating wounds of horses. Animals—6 horses. Procedures—On day 0, two 4-cm-diameter circular sections of full-thickness skin were removed from each of 2 randomly selected limbs of each horse, and two 4-cm-diameter circular skin grafts were harvested from the pectoral region. A skin graft was applied to 1 randomly selected wound on each limb, leaving the 2 nongrafted wounds to heal by second intention. On day 7, 2 grafts were harvested from the pectoral region and applied to the granulating wounds, and wounds grafted on day 0 were biopsied. On day 14, 1 wound was created on each of the 2 unwounded limbs, and the wounds that were grafted on day 7 were biopsied. All 4 ungrafted wounds (ie, 2 fresh wounds and 2 wounds with 1-week-old granulation beds) were grafted. The horses then received HBOT for 1 hour daily at 23 PSI for 7 days. On day 21, the grafts applied on day 14 were biopsied. Results—Histologic examination of biopsy specimens revealed that grafts treated with HBOT developed less granulation tissue, edema, and neovascularization, but more inflammation. The superficial portion of the graft was also less viable than the superficial portion of those not treated with HBOT. Conclusions and Clinical Relevance—The use of HBOT after full-thickness skin grafting of uncompromised fresh and granulating wounds of horses is not indicated.

Objective— To report use of a modified Whitehouse approach in standing horses for management of inspissated guttural pouch empyema. Study Design— Retrospective study. Animals— Adult horses (n=10) with guttural pouch empyema. Methods— Inspissated exudate in 1 or both guttural pouches was removed surgically through a modified Whitehouse approach, with the horses standing and sedated. Medical records of affected horses were reviewed to determine history; physical, endoscopic, and radiological examination findings; surgical technique; complications, and outcome. Results— All horses had purulent nasal discharge; 3 horses had dysphagia, 2 had recurrent laryngeal neuropathy on the side affected by guttural pouch empyema, and 1 had persistent soft palate displacement. Inspissated exudate was removed safely without causing apparent discomfort. Eight horses returned to their previous level of athletic activity after surgery; 1 horse dysphagic before surgery, was euthanatized because of persistent dysphagia after surgery, and 1 horse died 1 week after surgery for unknown reasons. Streptococcus equi subsp equi was isolated from the affected guttural pouch of 3 horses. Conclusions— Inspissated exudate can be removed surgically from the guttural pouch in standing horses through a modified Whitehouse approach. Clinical Relevance— To eliminate risks associated with general anesthesia and avoid surgical suite contamination, removal of chondroids can be performed in standing sedated horses through a modified Whitehouse approach.

The serum concentrations of serum amyloid A, haptoglobin and fibrinogen were measured in a group of horses before and at intervals after elective and non-elective surgery, and in a control group of normal horses. There was a significant, rapid and repeatable increase in the concentration of serum amyloid A in response to both elective and non-elective surgery. In the control horses its serum concentration was within the normal range, from 0 to 0.2 microg/ml. Twenty-four hours after elective surgery its mean peak concentration was 16.4 microg/ml, and after non-elective surgery it was 27.3 microg/ml. In contrast, the serum concentrations of haptoglobin and fibrinogen increased more slowly after surgery and had not decreased by 72 hours after surgery.

SummaryReasons for performing study A local anaesthetic agent capable of temporarily resolving lameness after being administered perineurally would be helpful because rapid return of lameness would allow for other analgesic techniques to be performed within a short period of time. Objectives To determine if a 3% solution of ketamine hydrochloride (HCl), administered around the palmar nerves at the level of the base of the proximal sesamoid bones, can improve naturally occurring lameness that can be improved or abolished with a basilar sesamoid nerve block performed using lidocaine HCl and to compare the change in gait produced using lidocaine to the change in gait produced using ketamine by using objective lameness assessment. Study design Experimental trial using research horses with naturally occurring lameness. Methods Seven horses, chronically lame on a thoracic limb, were chosen for the study. A wireless, inertial, sensor-based, motion analysis system was used to evaluate lameness before and after administration of 2% lidocaine and later, before and after administration of 3% ketamine over the palmar digital nerves at the base of the proximal sesamoid bones (a basilar sesamoid nerve block) at 5 min intervals for 30 min. Lameness scores obtained before and after administration of lidocaine and ketamine HCl were compared using repeated measures analysis. Results Gait significantly improved after basilar sesamoid nerve blocks using 2% lidocaine, but gait did not significantly improve after performing the same nerve block using 3% ketamine HCl. Conclusions Ketamine (3%) administered perineurally for regional anaesthesia of the digit does not desensitise the digit to the same extent as does lidocaine and thus 3% ketamine appears to have no value as a local anaesthetic agent for diagnostic regional anaesthesia.

This study was undertaken to determine whether resistance to moxidectin had developed in a large herd of draught horses, maintained on a small acreage, which had been routinely treated with moxidectin for five years. Faeces were collected for egg counts immediately before moxidectin gel was administered orally, and seven, 30, 60 and 90 days later. The faecal egg counts were significantly reduced at seven and 30 days after treatment, but were not significantly different from pretreatment counts at 60 and 90 days after treatment. There was no evidence of resistance having developed.

Summary Mixed lymphocyte culture and serological typing of NIH and Sinclair miniature swine indicate that the two herds share a common SLA haplotype. NIH haplotype a (International Haplotype H10) appears identical to Sinclair haplotype B, which has significant effects on the penetrance of Sinclair swine cutaneous malignant melanoma (SSCM). Offspring of crosses between melanoma-bearing Sinclair swine homozygous for the B haplotype and non-melanoma NIH aa swine have tumour incidence identical to Sinclair melanoma BB× Sinclair non-melanoma BB offspring. Our results provide further support for the involvement of the swine leucocyte antigen (SLA) complex in the inheritance of SSCM, and identify a new source of non-tumour animals that have all of the genes for SSCM except those at the tumour-initiator locus.

Objective—To evaluate the effect of a shunt created between the corpus cavernosum penis (CCP) and corpus spongiosum penis (CSP) on erectile and ejaculatory function of normal stallions and to verify persistence of the shunt. Study Design—The capability of stallions to develop an erection and to ejaculate was evaluated before and after creation of a corporeal shunt. Persistence of the shunt was determined by dye injection into the CCP at necropsy. Animals—Six stallions. Methods—A CCP-CSP shunt was created in five stallions. Semen was collected before and 4 to 14 weeks after surgery, before the horses were euthanatized. Dye was injected into the CCP to determine persistence of the shunt. Dye was also injected into the CCP of a control stallion. Results—All stallions had normal erectile and ejaculatory function before and after surgery. Dye, injected into the CCP, entered the CSP in three of five treated stallions, demonstrating persistence of the shunt, whereas in two stallions, dye was found only in the CCP, indicating closure of the shunt. No dye was detected in the CSP of the control stallion. Conclusions—Creation of a corporeal shunt does not interfere with normal erection and ejaculation of stallions. Shunt closure is not necessary for stallions to retain normal erectile and ejaculatory function. Clinical Relevance—Failure of a stallion affected by priapism to achieve normal erection or to ejaculate after creation of a corporeal shunt would likely be because of damage to corporeal tissue than from an effect of the shunt. ©Copyright 1999 by The American College of Veterinary Surgeons

Objective—To evaluate the effects of sequential anesthesia of the individual compartments of the equine stifle joint on lameness induced by intra-articular deposition of interleukin (IL)-1β. Animals—6 horses. Procedures—For each horse, baseline hind limb lameness was first evaluated. A randomly selected compartment of 1 stifle joint was then injected with IL-1β to induce synovitis and lameness; subsequently, the same compartment was anesthetized with 2% mepivacaine hydrochloride, and lameness was reevaluated. Two weeks later, baseline lameness was evaluated, and lameness was similarly induced; thereafter, the 2 synovial compartments of the stifle joint not injected with IL-1β were anesthetized sequentially in random order (ie, first and second blocks); lameness was evaluated after each block. Finally, the IL-1β–treated compartment was anesthetized (third block); lameness was again evaluated. This second experiment was repeated for the contralateral stifle joint 2 weeks later. Throughout the study, lameness was quantified objectively by assessing vertical pelvic movement asymmetry with a wireless, inertial sensor-based system. Results—Intra-articular deposition of IL-1β induced lameness in all injected limbs. In the first experiment, anesthesia of the compartment injected with IL-1β resulted in a significant decrease in lameness, with vertical pelvic movement asymmetry approaching baseline. In the second experiment, lameness improved significantly after the second and third blocks and was almost completely abolished after all 3 synovial compartments were anesthetized. Conclusions and Clinical Relevance—In horses, lameness caused by a lesion in 1 compartment of a stifle joint can be improved more by instillation of local anesthetic solution into that compartment than by anesthesia of the other compartments.

Summary Four mature pony geldings weighing an average of 134 kg and fitted with ileal cannulas were used in a 4×4 Latin square experiment to determine the digestibility of soybean meal (SBM) protein in different segments of the equine digestive tract at various levels of protein intake. A complete basal corn-based diet was supplemented with SBM to formulate four diets with increasing crude protein. The diets, labeled A (basal), B, C and D, contained 4.9%, 9.5%, 14% and 16.5% crude protein (as fed), and provided nitrogen, per feeding, at approximately 44.8, 84.3, 123.9 and 146.3 mg/kg of body weight, respectively. Chromic oxide was fed to measure ileal flow and fecal excretion. Digestion and absorption of nitrogen was determined from changes in nitrogen: chromium ratios, and true digestion of nitrogen was computed by regression analysis. True total tract digestion of nitrogen was 95.7%. True digestibility of nitrogen in the small intestine over the range of linearity was 72.2%, while true digestibility of nitrogen reaching the large intestine was 89.8%. These data indicate that the protein in SBM was almost completely digested in the equine digestive tract. Furthermore, approximately 75% of the digestible protein was digested prececally when nitrogen intake was less than approximately 125 mg/kg of body weight per feeding.

SummaryThe distal interphalangeal joint was successfully arthrodesed in a 7-monthold horse using two 13-mm stainless steel baskets that were packed with autogenous cancellous bone and held in place with transarticular 4.5-mm cortical screws. The baskets were placed midway between the extensor process of the distal phalanx and the collateral ligament on the corresponding side of the joint. The screws were directed from the abaxial side of the middle phalanx, axially and distally through the basket and across the joint space, into the distal phalanx. Bony fusion of the distal interphalangeal joint occurred through the region occupied by the baskets as well as through the central region of the joint. The horse was free of lameness at the walk in the operated limb from the fourth until the tenth postoperative month, at which time lameness recurred as a result of sepsis in the region of the lateral implant. An additional complication was the development of a carpus varus deformity in the contralateral forelimb, presumably as a result of stretching of the lateral collateral carpal ligaments from excessive weight-bearing coupled with an abnormal posture (tripod stance) during convalescence. The horse was euthanatized 10 months after the arthodesis procedure because of severe lameness associated with sepsis in the region of the lateral implant.Arthrodesis of the distal interphalangeal joint can be accomplished by inserting perforated stainless steel baskets into the joint.Modifications in the surgical approach to avoid complications of sepsis need to be made before this technique can be recommended for clinical application.Although the horse did not survive long-term, presentation of this technique should prove useful to other investigators as they attempt to devise techniques to fuse the distal interphalangeal joint.

To assess outcome after neurectomy of the deep branch of the lateral palmar nerve (DBLPaN) as a treatment for horses with persistent lameness associated with chronic proximal suspensory desmitis (PSD) of the thoracic limb.Case series.Adult, mixed-breed horses (n = 4), weighing 510-585 kg, used for amateur show-jumping.Records of 4 horses chronically lame because of PSD of one or both thoracic limbs that were treated by neurectomy of the DBLPaN were reviewed. The site of pain causing lameness was localized using regional anesthesia. The proximal aspect of the suspensory ligament of the affected limb(s) of all horses were enlarged on ultrasonographic examination, but fiber disruption was not observed. All horses remained lame after conservative therapy. Neurectomy was performed with the horses anesthetized and positioned in dorsal recumbency.All 4 horses were sound at 6 weeks and remained sound for at least 12 months after neurectomy.Lameness in horses caused by chronic PSD can be resolved by neurectomy of the DBLPaN in horses that are refractory to conservative management.