OBJECTIVE To characterize and describe the compensatory load redistribution that results from unilateral hind limb lameness in horses.
DESIGN Retrospective case series.
ANIMALS 37 client-owned horses.
PROCEDURES Medical records were reviewed to identify horses with unilateral hind limb lameness that responded positively (by objective assessment) to diagnostic local anesthesia during lameness evaluation and that were evaluated before and after diagnostic local anesthesia with an inertial sensor-based lameness diagnosis system. Horses were grouped as having hind limb lameness only, hind limb and ipsilateral forelimb lameness, or hind limb and contralateral forelimb lameness. Measures of head and pelvic movement asymmetry before (baseline) and after diagnostic local anesthesia were compared. The effect of group on baseline pelvic movement asymmetry variables was analyzed statistically.
RESULTS Maximum pelvic height significantly decreased from the baseline value after diagnostic local anesthesia in each of the 3 lameness groups and in all horses combined. Minimum pelvic height significantly decreased after the procedure in all groups except the hind limb and contralateral forelimb lameness group. Head movement asymmetry was significantly decreased after diagnostic local anesthesia for horses with hind limb and ipsilateral forelimb lameness and for all horses combined, but not for those with hind limb lameness only or those with hind limb and contralateral forelimb lameness.
CONCLUSIONS AND CLINICAL RELEVANCE Results supported that hind limb lameness can cause compensatory load redistribution evidenced as ipsilateral forelimb lameness. In this population of horses, contralateral forelimb lameness was not compensatory and likely reflected true lameness. Further studies are needed to investigate the source of the contralateral forelimb lameness in such horses.
OBJECTIVE To evaluate ex vivo cyclooxygenase (COX) inhibition and compare in vitro and ex vivo COX-1 inhibition by flunixin meglumine and firocoxib in horses.
ANIMALS 4 healthy horses for in vitro experiments and 12 healthy horses (6 males and 6 females; 5 Thoroughbreds, 5 Warmbloods, and 2 ponies) undergoing elective surgery for ex vivo experiments.
PROCEDURES 12 horses received flunixin meglumine (1.1 mg/kg, IV, q 12 h) or firocoxib (0.09 mg/kg, IV, q 24 h). Blood samples were collected before (baseline) and 2 and 24 hours after NSAID administration. Prostanoids (thromboxane B2, prostaglandin E2, and prostaglandin E metabolites) served as indicators of COX activity, and serum drug concentrations were measured by use of high-performance liquid chromatography. An in vitro coagulation-induced thromboxane B2 assay was used to calculate drug concentration-COX-1 inhibition curves. Effect of time and treatment on COX activity was determined. Agreement between in vitro and ex vivo measurement of COX activity was assessed with Bland-Altman analysis.
RESULTS At 2 and 24 hours after NSAID administration, COX-1 activity was reduced, compared with baseline activity, for the flunixin meglumine group only and relative COX-1 activity was significantly greater for the firocoxib group, compared with that for the flunixin meglumine group. There was no significant change in COX-2 activity after surgery for either group. Bland-Altman analysis revealed poor agreement between in vitro and ex vivo measurement of COX-1 activity.
CONCLUSIONS AND CLINICAL RELEVANCE Compared with flunixin meglumine, firocoxib had COX-1-sparing effects ex vivo in equine patients that underwent elective surgery.
Case Description—A 7-year-old sexually intact male Thoroughbred racehorse was evaluated because of exercise intolerance, respiratory tract noise, and coughing when eating.
Clinical Findings—A persistent dorsal displacement of the soft palate was identified during endoscopic examination of the upper portions of the respiratory tract. Radiography of the pharyngeal and laryngeal regions revealed a hypoplastic epiglottis that was ventral to, and not in contact with, the soft palate. The horse was anesthetized, and an oral endoscopic examination revealed a subepiglottic frenulum that had resulted in the dorsal displacement of the soft palate.
Treatment and Outcome—The frenulum was transected transendoscopically by use of a diode laser. Twenty-four hours following surgery, repeat endoscopic and radiographic examinations revealed that the epiglottis had returned to its correct anatomic position in relation to the soft palate. Four weeks after surgery, endoscopy of the upper portions of the airway revealed recurrence of the dorsal displacement of the soft palate.
Clinical Relevance—A subepiglottic frenulum should be considered as a cause of persistent dorsal displacement of the soft palate in horses. An endoscopic examination of the oropharyngeal region should be performed in horses prior to undertaking any surgical interventions to treat persistent dorsal displacement of the soft palate.
Objective—To determine the incidence of unilaterally castrated horses among horses admitted to the hospital for castration and to compare horses that underwent previous unilateral castration with horses that had cryptorchism.
Design—Retrospective case series.
Animals—16 unilaterally castrated horses and 44 cryptorchid horses.
Procedures—Medical records of horses that were admitted to the veterinary medical teaching hospital for castration, including cryptorchid and unilaterally castrated horses, between January 2002 and December 2006 were reviewed. Medical records of unilaterally castrated horses and cryptorchid horses were examined for age, breed, history, diagnostic procedures, surgical technique of cryptorchidectomy, location of the retained testicle, and cost of surgery.
Results—Of 160 horses admitted for castration, 16 (10%) had undergone previous unilateral castration and 44 (27.5%) had cryptorchidism. Unilaterally castrated horses were significantly older than cryptorchid horses. No significant difference was found in left versus right distribution of testicles. No significant difference was found in abdominal versus inguinal distribution of left-sided testicles. Unilaterally castrated horses had a significantly lower proportion of right inguinal testicles, compared with cryptorchid horses. The cost of diagnosis and management of unilaterally castrated horses was significantly greater than in cryptorchid horses.
Conclusions and Clinical Relevance—Results indicated that the distribution of retained testicles is significantly different in unilaterally castrated horses, compared with cryptorchid horses, which may affect the selection of diagnostic and surgical approaches to unilaterally castrated horses.
Objective—To determine demographic characteristics of horses donated to the North Carolina State University Equine Health Center (EHC) between 1996 and 2008.
Design—Retrospective cohort study.
Animals—122 horses donated to the EHC between January 1996 and December 2008, and 246 horses offered for donation to the EHC between January 2007 and December 2008.
Procedures—Telephone and medical records were examined. Data were collected in 5 categories: age, sex, breed, reason for donation, and use prior to donation.
Results—From January 1996 through December 2008, 122 horses were donated to the EHC (median, 3 horses/y; range, 0 to 39 horses/y). There were 131 and 115 horses offered for donation during 2007 and 2008, respectively, of which 38 and 23 were accepted. Mean ± SD age of horses offered for donation during 2007 and 2008 was 12.7 ± 6.7 years, with 75 of the 246 (30.5%) horses between 6 and 10 years old. Musculoskeletal disease was the most commonly listed reason horses were offered for donation (115/240 [47.9%]).
Conclusions and Clinical Relevance—Results indicated that unwanted horses donated to the EHC between 1996 and 2008 spanned a wide range of ages and breeds and included both males and females. The most common reason given for unwanted horses offered for donation during 2007 and 2008 was musculoskeletal disease, with degenerative joint disease, lameness of undetermined cause, laminitis, and navicular disease being the most common musculoskeletal conditions.
Objective—To determine the cyclooxygenase (COX) selectivity of robenacoxib and its effect on recovery of jejunal mucosa following ischemic injury in horses.
Animals—12 healthy horses.
Procedures—Half the maximal inhibition (EC50) of robenacoxib for COX-1 and COX-2 activity was established in bloods samples from 6 horses via measurement of thromboxane B2 (TXB2) and prostaglandin E2 concentrations, respectively; COX selectivity was subsequently calculated. Six other horses were anesthetized, and ischemia was induced in the jejunum for 2 hours. Control and ischemia-injured mucosa were collected and incubated with Ringer's solution (control treatment), flunixin meglumine (2.7 × 10−5M), or robenacoxib (2.7 × 10−5M). Transepithelial electrical resistance and mannitol flux were measured over a 4-hour recovery period. Bathing solution TXB2 and prostaglandin E metabolite concentrations were measured to assess COX-1 and COX-2 function, respectively.
Results—The mean ± SD EC50 value of robenacoxib for COX-1 and COX-2 was 11.46 ± 4.46μM and 0.19 ± 0.07μM, respectively, resulting in a COX selectivity ratio of 61.01. The transepithelial electrical resistance of ischemia-injured jejunum treated with flunixin meglumine was significantly lower than that of control and robenacoxib-treated tissues. A significant increase in concentrations of prostaglandin E metabolites and TXB2 was detected in control and robenacoxib-treated tissues but not flunixin meglumine—treated tissues.
Conclusions and Clinical Relevance—Robenacoxib selectively inhibited COX-2 and allowed recovery of barrier function in ischemia-injured equine jejunal tissue in vitro.
Objective—To investigate effects of lidocaine hydrochloride administered IV on mucosal inflammation in ischemia-injured jejunum of horses treated with flunixin meglumine.
Procedures—Horses received saline (0.9% NaCl) solution (SS; 1 mL/50 kg, IV [1 dose]), flunixin meglumine (1 mg/kg, IV, q 12 h), lidocaine (bolus [1.3 mg/kg] and constant rate infusion [0.05 mg/kg/min], IV, during and after recovery from surgery), or both flunixin and lidocaine (n = 6/group). During surgery, blood flow was occluded for 2 hours in 2 sections of jejunum in each horse. Uninjured and ischemia-injured jejunal specimens were collected after the ischemic period and after euthanasia 18 hours later for histologic assessment and determination of cyclooxygenase (COX) expression (via western blot procedures). Plasma samples collected prior to (baseline) and 8 hours after the ischemic period were analyzed for prostanoid concentrations.
Results—Immediately after the ischemic period, COX-2 expression in horses treated with lidocaine alone was significantly less than expression in horses treated with SS or flunixin alone. Eighteen hours after the ischemic period, mucosal neutrophil counts in horses treated with flunixin alone were significantly higher than counts in other treatment groups. Compared with baseline plasma concentrations, postischemia prostaglandin E2 metabolite and thromboxane B2 concentrations increased in horses treated with SS and in horses treated with SS or lidocaine alone, respectively.
Conclusions and Clinical Relevance—In horses with ischemia-injured jejunum, lidocaine administered IV reduced plasma prostaglandin E2 metabolite concentration and mucosal COX-2 expression. Coadministration of lidocaine with flunixin ameliorated the flunixin-induced increase in mucosal neutrophil counts.
OBJECTIVE To characterize aminoaciduria and plasma amino acid concentrations in dogs with hepatocutaneous syndrome (HCS).
ANIMALS 20 client-owned dogs of various breeds and ages.
PROCEDURES HCS was definitively diagnosed on the basis of liver biopsy specimens (n = 12), gross and histologic appearance of skin lesions (4), and examination of skin and liver biopsy specimens (2) and presumptively diagnosed on the basis of cutaneous lesions with compatible clinicopathologic and hepatic ultrasonographic (honeycomb or Swiss cheese pattern) findings (2). Amino acid concentrations in heparinized plasma and urine (samples obtained within 8 hours of each other) were measured by use of ion exchange chromatography. Urine creatinine concentration was used to normalize urine amino acid concentrations. Plasma amino acid values were compared relative to mean reference values; urine-corrected amino acid values were compared relative to maximal reference values.
RESULTS All dogs had generalized hypoaminoacidemia, with numerous amino acid concentrations < 50% of mean reference values. The most consistent and severe abnormalities involved glutamine, proline, cysteine, and hydroxyproline, and all dogs had marked lysinuria. Urine amino acids exceeding maximum reference values (value > 1.0) included lysine, 1-methylhistidine, and proline.
CONCLUSIONS AND CLINICAL RELEVANCE Hypoaminoacidemia in dogs with HCS prominently involved amino acids associated with the urea cycle and synthesis of glutathione and collagen. Marked lysinuria and prolinuria implicated dysfunction of specific amino acid transporters and wasting of amino acids essential for collagen synthesis. These findings may provide a means for tailoring nutritional support and for facilitating HCS diagnosis.