Ventricular arrhythmias in horses: 21 cases (1984-1989).

Ventricular premature depolarizations (VPD) were identified in 21 horses in which unexplained tachycardia or an arrhythmia was detected on auscultation. Horses were categorized into 3 groups on the basis of ECG findings. Seven horses had uniform isolated VPD (group 1); 7 horses had repetitive uniform VPD at a rate < 100 VPD/min (group 2); and 7 horses had either multiform VPD, R-on-T, or > or = 100 VPD/min (group 3). Concurrent systemic disease was identified in 12 horses, 7 of which had gastrointestinal tract disorders. Serum cardiac isoenzyme activities were high in 6 (2 from each group) of 13 horses in which they were measured. Serum electrolyte concentrations were normal in all but 1 of 11 horses in which they were measured. Antiarrhythmic drugs were given to 9 horses (all of which were in group 2 or group 3), 6 of which converted to sinus rhythm. Two horses that had R-on-T in the ECG died shortly after initiation of antiarrhythmic treatment. An accelerated idioventricular rhythm persisted in 1 horse for at least 8 months and failed to respond to antiarrhythmic drugs. Ventricular premature depolarizations resolved or decreased considerably in frequency in 11 horses without the administration of antiarrhythmic agents. Treatment in these horses included therapy for any underlying systemic disease, corticosteroids, nonsteroidal antiinflammatory drugs, or stall rest. The remaining horse was euthanatized several hours after hospitalization. Five horses died or were euthanatized either during hospitalization or several months after being discharged. Myocardial lesions were identified at necropsy in 2 horses.     

Effect of gentamicin sulfate and sodium bicarbonate on the synovium of clinically normal equine antebrachiocarpal joints

The effect of gentamicin sulfate, unbuffered and buffered with sodium bicarbonate, on synovial fluid and membrane of clinically normal equine joints was evaluated. Thirty-six adult horses with clinically normal antebrachiocarpal joints were allotted to 6 treatment groups of 6 horses each. One antebrachiocarpal joint in each horse was chosen for treatment. Group-1 horses were given gentamicin (3 ml; 50 mg/ml); group-2 horses were given sodium bicarbonate (3 ml; 1 mEq/ml); group-3 horses were given gentamicin (3 ml; 50 mg/ml) and sodium bicarbonate (3 ml; 1 mEq/ml); group-4 horses were not treated; and horses of groups 5 and 6 were given polyionic physiologic solution (3 and 6 ml, respectively). Synovial fluid specimens were obtained from 5 horses of each group for cytologic analysis at postinjection hours (PIH) 0, 24, 72, and 192 and for pH determination at PIH 0, 0.25, 0.5, 1, 4, 8, 24, 72, and 192. The sixth horse of each group was euthanatized at PIH 24, and the synovial membrane of the treated and contralateral (nontreated) antebrachiocarpal joints was examined macroscopically and microscopically. After intra-articular gentamicin administration, the mean synovial fluid pH was lowest (5.98) at PIH 0.25, but by PIH 8, it was not significantly different from the control value (group-5 horses). When sodium bicarbonate was combined with gentamicin before intra-articular administration, the mean synovial fluid pH was lowest (7.07) at PIH 0.25, but by PIH 1, it was not significantly different from the control value (group-6 horses).(ABSTRACT TRUNCATED AT 250 WORDS)     

Progression of Femoropatellar Osteochondrosis in Nine Young Horses Clinical, Radiographic and Arthroscopic Findings

The clinical and radiographic progression, and arthroscopic findings for nine young horses (<1 year of age) with femoropatellar osteochondrosis (OCD) are presented. Horses had a 2 to 12 week history of bilateral (8 horses) or unilateral (1 horse) hindlimb lameness. The most consistent clinical signs included femoropatellar joint distention and bilateral hindlimb lameness. At the onset of clinical signs, radiographic lesions were not present (4 horses) or subtle (5 horses), but were easily identified on radiographs taken 4 to 24 weeks later. Arthroscopic surgery was delayed until radiographic changes became obvious. Surgical findings in 20 femoropatellar joints were most commonly osteochondral "flaps" located on the proximal lateral trochlear ridge of the femur and were larger than had been indicated by the radiographs. Eight horses were being used for their intended purpose, which was racing (3 horses were racing and 3 were in race training), dressage (1 horse) or pleasure riding (1 horse). One horse required a second surgery when similar lesions developed in the opposite stifle, and was euthanatized 2 months later because of persistent lameness. Once clinical signs are observed, osteochondrosis lesions of the distal femur can progress in foals younger than 9 months of age and the full extent of the radiographic lesion may take several weeks to develop.     

Efficacy of ivermectin in paste and injectable formulations against microfilariae of Onchocerca cervicalis and resolution of associated dermatitis in horses

The efficacy of a single dose of ivermectin (0.2 mg/kg), in injectable or paste formulations, against microfilariae of Onchocerca cervicalis and associated skin lesions was evaluated in 20 naturally infected horses during midsummer months in Louisiana. All horses had clinical signs of dermatitis of the ventral midline and/or limbs, shoulders, thorax, and withers. Efficacy was monitored at 21, 42, and 63 days after treatment. Procedures done at these intervals included microfilarial counts of 6-mm skin biopsy specimens of affected ventral midline, grading of gross lesions, and photography and histologic assessment of ventral midline biopsy specimens. Microfilarial numbers were reduced to 0 by 21 days after treatment in all but one horse. Active lesions improved or were resolved completely by 63 days after treatment. Total inflammation, as judged by histologic methods, was reduced in all horses by 63 days after treatment, but there was a residual population of inflammatory cells in all horses. Adverse reactions after treatment were not observed in any of the horses.     

Subchondral cystic lesions of the proximal extremity of the tibia in horses: 12 cases (1983-2000)

OBJECTIVE: To determine clinical and radiographic features of subchondral cystic lesions (SCL) of the proximal extremity of the tibia in horses that could be used to classify these lesions as being related to osteochondrosis or osteoarthritis and to evaluate results of surgical debridement. DESIGN: Retrospective study. ANIMALS: 12 horses with 14 SCL. PROCEDURE: Medical records and radiographs obtained before and after treatment were reviewed. RESULTS: In 6 young horses (8 lesions), SCL were considered to be related to osteochondrosis; all involved the lateral tibial condyle. The remaining 6 horses were mature and had radiographic evidence of osteoarthritis in addition to SCL. Arthroscopic debridement was performed in 4 horses in which lesions were considered to be a result of osteochondrosis and in 3 horses with osteoarthritis. Three horses in which SCL were considered to be a result of osteochondrosis performed athletically after debridement. Two horses with moderate osteoarthritis returned to work after arthroscopic debridement but at a lower level of athletic performance. One horse with SCL related to osteochondrosis responded to medical treatment and went on to race. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that arthroscopic debridement of SCL is feasible in horses in which lesions involve the cranial portion of the lateral or medial tibial condyle, and that treated horses may be able to perform athletically.     

Keratomas in horses: seven cases (1975-1986)

The diagnosis of keratoma in 7 horses and their treatment and outcome were evaluated. Horses were 2 to 20 years old, of various breeds, and were intact or castrated males. All were lame, and 6 horses had had previous injuries of the affected hoof that had not responded to prior treatments. Only 1 hoof was affected in each horse. Keratomas were beneath the hoof wall (6 horses) or sole (1 horse). Radiographically, a circular or semicircular defect with a discrete margin was present in the distal portion of the third phalanx in 3 horses. Grossly, keratomas were firm solitary masses (1.5 to 5 cm diameter); gray, tan, or yellow; and oval or conical. Keratomas were excised from beneath the hoof wall by removing a section of hoof wall (5 horses) or by undermining the wall beginning at its junction with the sole (1 horse). A keratoma beneath the sole in 1 horse was excised by excavating the sole to the level of the palmar surface of the third phalanx. Keratoma was verified microscopically by the presence of characteristic rings of squamous epithelial cells with abundant keratin. Purulent exudate and inflammatory infiltrate often were present concurrently, reflecting an associated localized infection. Aftercare included daily application of an antiseptic iodine solution and foot bandages, and shoeing with a treatment plate several weeks after surgery. Hoof and sole defects healed completely between 6 months and 1 year. By 1 year after surgery, 6 horses were sound, and keratoma had not recurred.     

Pathomorphological study on gastroduodenal ulceration in horses: localisation of lesions

Gastroduodenal ulceration is a prevalent disease in foals and adult horses. Decreased performance as well as fatal complications relate to this syndrome. The objective of our study was to determine the prevalence of gastric ulceration in a mixed population of horses by postmortem examination and to evaluate a possible association between equine gastric ulcer syndrome (EGUS) and sex or age of the examined horses, to evaluate the localisation of lesions in the proximal part of the gastrointestinal tract and to determine the occurrence of gastric parasites. Postmortem examinations were performed on 71 horses over a period of 24 months. Gastric ulcers were found in 52 horses (73.2%). There was no significant association between age or sex and occurrence of gastric ulcers. In all horses the squamous mucosa lesions were localised near the margo plicatus (100% of the cases), whereas in 23 horses the lesions were near the margo plicatus and lesser curvature and in 7 horses at the greater curvature. In 18 horses the mucosa was affected in the whole extent of the margo plicatus and in 1 horse diffuse lesions of the squamous mucosa were noted. Lesions of the glandular mucosa were localised in 11 horses at the fundic area, in 1 horse they occurred in the pylorus, and in 10 horses diffuse lesions of the glandular mucosa were recorded. A low prevalence of Gasterophilus intestinalis infection was detected (1 horse, 1.4%). We have confirmed that gastric ulcers are a common problem in horses and duodenal or oesophageal ulceration is rare (not a single case of the latter was found in this study). Lesions in the glandular mucosa of the stomach are more frequent in suckling foals than in older animals. Lesions of the glandular mucosa are also common in adult horses, and a complete gastroscopic examination including examination of the pylorus is advisable to evaluate this syndrome.     

Neodymium:yttrium-aluminum-garnet laser-assisted excision of progressive ethmoid hematomas in horses: 20 cases (1986-1996)

OBJECTIVE: To describe a technique of contact neodymium:yttrium-aluminum-garnet (Nd:YAG) laser-assisted excision of progressive ethmoid hematoma (PEH) in horses, to determine the recurrence rate of clinical signs of PEH in horses with follow-up time of a minimum of 12 months, and to compare this result with reported results achieved by using conventional techniques. DESIGN: Retrospective study. ANIMALS: 21 horses with 26 PEH. PROCEDURE: Medical records of all horses with PEH treated by Nd:YAG laser excision from December 1986 through August 1996 were analyzed. Twenty-one horses underwent unilateral (18 surgeries) or bilateral (14) frontonasal bone flap with excision of the mass, using an Nd:YAG laser. One horse with bilateral PEH underwent a unilateral bone flap twice, 1 year apart. RESULTS: 1 horse died. Four of 20 horses with followup times of 12 months or longer had recurrence of PEH. The PEH recurrence rate was 20% (5/25 PEH). Three of 6 horses with bilateral lesions had recurrence of PEH. Recurrence rate for horses that had bilateral PEH (3/6 horses) was greater than for horses with unilateral PEH (1/14 horses). CLINICAL IMPLICATIONS: Treatment of PEH by Nd:YAG laser excision through a frontonasal bone flap results in a recurrence rate comparable with that reported for conventional techniques. Horses with bilateral lesions are more likely to have a recurrence of PEH.     

Surgical treatment of 45 horses affected by squamous cell carcinoma of the penis and prepuce

The medical records of 45 horses treated for suspected squamous cell carcinoma of the penis and/or prepuce were reviewed. The age of 40 horses was known, and these had a mean age of 17.4 years. The duration of neoplasia was known for only 3 of the 45 horses. The results of histological evaluation of lesions, available for 35 horses, confirmed that the diseased tissue was squamous cell carcinoma. The location of gross neoplastic lesions was recorded for 43 horses; the glans penis was involved in 24 horses, the body of the penis or the inner lamina of the preputial fold in 27 horses, and the external fold of the prepuce in 10 horses. Surgical treatments of these horses included phallectomy (penile amputation) in 35 horses, segmental posthectomy in 4 horses, phallectomy plus segmental posthectomy in 2 horses, and en bloc resection of the penis, prepuce and superficial inguinal lymph nodes with penile retroversion in 4 cases. Short-term complications in the immediate postoperative period included preputial oedema and haemorrhage at the end of urination. One horse developed acute urinary retention because of severe urethral oedema. Long-term (>1 year) follow-up information was obtained for 31 horses. Neoplasia of the penis and/or prepuce recurred in 6 of these 31 horses (19%), and in 5 of these the recurrence necessitated euthanasia of the horse.     

Genital neoplasms treated by en bloc resection and penile retroversion in horses: 10 cases (1977-1986)

The medical records of 10 horses with invasive neoplasms of the penis, prepuce, and/or superficial inguinal lymph nodes in which treatment involved en bloc resection and penile retroversion were reviewed. All were geldings and ranged in age from 12 to 25 years (mean, 19 years). Evaluation of biopsy specimens obtained before surgery confirmed lymphosarcoma in 1 horse and squamous cell carcinoma in 9 horses. Typical history included swelling, ulceration, and abscessation of the penis and prepuce and large superficial inguinal lymph nodes. Complications after surgery included dehiscence of the urethrostomy site (4 horses), dehiscence of the ventral skin incision (1 horse), urine scalding of 1 hind limb (1 horse), cystitis (1 horse), severe hemorrhage (1 horse), and diarrhea (1 horse). One horse was euthanatized during hospitalization, because of severe dehydration secondary to diarrhea. At necropsy, firm nodules were scattered in the pulmonary parenchyma, myocardium, thyroid gland, parathyroid glands, cranial mediastinum, kidneys, and hilar lymph nodes. Microscopic examination of the nodules revealed undifferentiated carcinoma. Nine horses were discharged from the hospital between 1 and 5 weeks after surgery. The mean follow-up interval was 27 months (range, 6 to 96 months). Eight horses had no evidence of recurrence. One horse had recurrence of neoplasm at 6 months and was euthanatized 12 months later.     

Loop colostomy for management of rectal tears and small-colon injuries in horses: 10 cases (1976-1989).

Loop colostomy was performed in 10 horses as treatment for grade-III rectal tears (n = 6 horses), small-colon infarction (n = 2 horses), perirectal abscess and stenosis (n = 1 horse), and small-colon stricture (n = 1 horse). In 7 horses, the colostomy was constructed through a single incision low in the left flank, with closure of the incision around the stoma (single-incision technique). In 3 horses, 2 of which had colostomy performed as a standing procedure, the selected segment of small colon was placed from a flank incision into a separate, small incision low in the left flank (double-incision technique). Five horses underwent colostomy reversal (at 18 to 63 days) and 2 of these horses, both with grade-III rectal tears, recovered completely. Of 8 horses that did not survive, 6 died from the primary disease or associated complications. Technical problems associated with colostomy accounted for death of 2 horses. One horse had gastric rupture attributable to suture occlusion of the small intestine after colostomy reversal, and another horse had complications of incisional infection after repair of a peristomal hernia. Small-colon prolapse through the stoma necessitated premature reversal of the colostomy in a horse that was euthanatized because of worsening laminitis. Minor complications of the colostomy procedure were partial stomal dehiscence (n = 4 horses), partial dehiscence of the flank wound after colostomy reversal (n = 2 horses), and small ventral midline hernia after colostomy reversal (n = 1 horse). Loop colostomy may be of benefit to horses with rectal tears, provided it is done soon after the tear occurs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Results of surgical treatment of colic in miniature breed horses: 11 cases

OBJECTIVE: To report on the outcome of surgical treatment of acute abdominal crises in miniature breed horses. DESIGN: Retrospective case series of miniature horses presented to the University Veterinary Centre, Camden with an acute abdominal crisis. METHODS: Hospital records of all miniature horses that underwent ventral midline laparotomy for acute abdominal crisis between 1997 and 2001 were reviewed. The signalment, history, clinical signs, results of ancillary diagnostic procedures, location and type of intestinal lesion, treatment and outcome were retrieved from each case record. Long-term survival was determined by telephone interview of owners. RESULTS: Eleven miniature horses including five females and six males underwent ventral midline laparotomies for acute abdominal crisis during the study period. Ages ranged between 1 month and 19 years. Surgical findings included faecalith obstruction (seven horses), enterolith (one horse), strangulating lipoma of the descending colon (one horse), jejunal infarction (one horse), and caecal infarction (one horse). Long-term survival rate (minimum 12 months post surgery) was 55%. Six of eight horses with simple intraluminal obstructions survived, while the three horses with gastrointestinal lesions associated with vascular compromise were euthanased either at surgery (caecal infarction), or postoperatively, due to complications (strangulating lipoma of the descending colon, jejunal infarction). Postoperative complications in this study included impaction of the descending colon (two horses), diarrhoea (two horses), peritonitis (one horse), hyperlipaemia (two horses), incisional infection (two horses) and abdominal adhesions (one horse). Hyperlipidaemia was present in five of seven horses in which serum triglycerides were measured at presentation. CONCLUSIONS: Simple intraluminal obstructions of the large intestine were frequently encountered during exploratory laparotomy in miniature horses presented for acute abdominal crises, and their surgical treatment was associated with a good prognosis. In contrast, this study suggested that abdominal pain associated with vascular compromise of gastrointestinal tissues in miniature horses was associated with a poorer prognosis, consistent with reports in other horse breeds. Possible contributing factors to faecalith formation, including poor quality roughage, dental disease, and inadequate water consumption, should be recognised and avoided in miniature horses. Serum triglyceride concentrations should be measured in miniature horses presented for acute abdominal pain. If elevated, nutritional supplementation should be provided.     

Septic tenosynovitis in horses: 25 cases (1983-1989).

The medical records of 25 horses with septic tenosynovitis treated over 7 years (1983 to 1989) were reviewed to determine clinical features of the disease and response to treatment. The median age of horses with septic tenosynovitis was 5 years (range, 1 month to 21 years). Fourteen fore limbs and 11 hind limbs were affected. Sepsis was located in the sheath of the digital flexor tendons of 22 horses. Sepsis was located in the sheath of the extensor carpi radialis tendon (1 horse), sheath of the long digital extensor tendon (1 horse), or sheath of the common digital extensor tendon (1 horse) in the remaining horses. Nine horses received only medical treatment, using a combination of broad-spectrum parenterally administered antimicrobial drugs (8 of 9 horses), nonsteroidal anti-inflammatory drugs (8 of 9 horses), or irrigation of the wound (4 of 9 horses). Fourteen horses were treated surgically with either transection of the palmar/plantar annular ligament of the metacarpo/metatarsophalangeal joint (5 of 14 horses), lavage of the sheath after insertion of drains into the sheath (7 of 14 horses), or both (2 of 14 horses). All horses treated surgically were concurrently treated parenterally with broad-spectrum antimicrobial drugs and nonsteroidal anti-inflammatory drugs. Two horses with septic tenosynovitis were not treated and were euthanatized at the owners' request. Five horses were euthanatized before discharge from the hospital. Two horses (both treated medically) were lost to follow-up. Follow-up information was obtained for 18 horses, 6 to 55 months after discharge from the hospital.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sudden death attributable to exercise-induced pulmonary hemorrhage in racehorses: nine cases (1981-1983)

Pathologic changes are described in 11 horses that died during racing or training; 9 died of acute pulmonary hemorrhage (exercise-induced pulmonary hemorrhage), 1 died of exsanguination, and 1 died of CNS trauma. Cardiac lesions were not found in any horse. Severe engorgement of pulmonary vessels, with hemorrhage into alveoli, airways, interstitium, and subpleural tissues, was observed in all 9 horses that died of exercise-induced pulmonary hemorrhage. Infiltration of eosinophils and/or lymphocytes around vessels and airways was seen in 6 horses. Focally extensive fibrosis was observed in the pleura and interstitium of 6 horses, and collections of siderophages were seen in the fibrous tissue and in the airways. Focal occlusion of bronchioles with inspissated mucus, such as that associated with small airway disease, was found in 4 horses. Underlying respiratory tract lesions, particularly those associated with small airway disease or bronchiolitis, may have a role in fatal pulmonary hemorrhage.     

Pharmacokinetics of azathioprine following single-dose intravenous and oral administration and effects of azathioprine following chronic oral administration in horses

OBJECTIVE: To determine pharmacokinetics of azathioprine (AZA) and clinical, hematologic, and serologic effects of i.v. and oral administration of AZA in horses. ANIMALS: 6 horses. PROCEDURE: In study phase 1, a single dose of AZA was administered i.v. (1.5 mg/kg) or orally (3.0 mg/kg) to 6 horses, with at least 1 week between treatments. Blood samples were collected for AZA and 6-mercaptopurine (6-MP) analysis 1 hour before and at predetermined time points up to 4 hours after AZA administration. In study phase 2, AZA was administered orally (3 mg/kg) every 24 hours for 30 days and then every 48 hours for 30 days. Throughout study phase 2, blood samples were collected for CBC determination and serum biochemical analysis. RESULTS: Plasma concentrations of AZA and its metabolite, 6-MP decreased rapidly from plasma following i.v. administration of AZA, consistent with the short mean elimination half-life of 1.8 minutes. Oral bioavailability of AZA was low, ranging from 1% to 7%. No horses had abnormalities on CBC determination or serum biochemical analysis, other than 1 horse that was lymphopenic on day 5 and 26 of daily treatment. This horse developed facial alopecia from which 1 colony of a Trichophyton sp was cultured; alopecia resolved within 1 month after the study ended. CONCLUSIONS AND CLINICAL RELEVANCE: Overall, no adverse effects were observed with long-term oral administration of AZA to horses, although 1 horse did have possible evidence of immunosuppression with chronic treatment. Further investigation of the clinical efficacy of AZA in the treatment of autoimmune diseases in horses is warranted.     

Pedunculated lipomas as a cause of intestinal obstruction in horses: 17 cases (1983-1990).

The medical records of 17 horses that were evaluated and treated because of colic caused by pedunculated lipomas between 1983 and 1990 were reviewed. The mean age of the horses was 16.6 +/- 3.9 years (range, 10 to 26 years), which was significantly greater than that of the population of horses evaluated because of colic (control population) during the same period. There were significantly more geldings (76.5%), compared with the control population. Nasogastric reflux ranged from 1 to 16 L in 8 horses and was not obtained in 9 horses. Abdominal palpation per rectum revealed small intestinal distention in 13 horses, displaced large colon in 7 horses, and large colon impaction in 2 horses. Peritoneal fluid was abnormal in 11 of 12 horses from which it was obtained successfully. One horse was euthanatized after unsuccessful medical treatment. Surgery was performed in 16 horses. Lipomas were blindly resected in 5 horses or exteriorized and resected in 6 horses. The method used to resect the lipoma was not recorded in 5 horses. The ileum and/or jejunum was strangulated in 15 horses, the small colon was strangulated in 1 horse, and the jejunum was obstructed in 1 horse. The length of intestine resected ranged from 0.15 to 7.2 m. Fourteen horses survived surgery, of which 11 were discharged from the hospital (short-term survival rate of 78.6%). Excluding 2 horses lost to follow-up evaluation, 6 of 12 horses that survived surgery were alive 2 to 56 months following surgery (long-term survival rate of 50%), and 9 of 15 horses died or were euthanatized (fatality rate of 60%).     

Diagnosis, relative incidence, and probable cause of cunean tendon bursitis-tarsitis of Standardbred horses

A prospective study of the diagnostic results on 25 previously untreated, slightly lame Standardbred horses showed that manipulative tests are of some help in diagnosis. The lameness of each horse was diminished or the horse went lame on the opposite limb after being given an injection of anesthetic in the cunean bursa, and lameness improved more when local anesthetic was injected in the distal intertarsal and tarsometatarsal articulations. In four horses, lesions of the distal articulation of the hock were evident on radiography.     

Treatment of Atrial Fibrillation in Horses: New Perspectives

Forty-one horses were treated for atrial fibrillation (AF) with 22 mg/kg quinidine sulfate via nasogastric tube every 2 hours until conversion to sinus rhythm, a cumulative dose of 88 to 132 mg/kg had been administered in 2-hour increments, or the horse had adverse or toxic effects from the drug. Treatment intervals were prolonged to every 6 hours if conversion had not occurred. Digoxin was administered before treatment if the horse had a fractional shortening ≤ 27% (3 horses), was prone to tachycardia (resting heart rate ≥ 60 beats/min) (1 horse), or had a previous history of sustained tachycardia of over 100 beats/min during prior conversion (3 horses). Digoxin was administered during day 1 of quinidine sulfate treatment if the horse developed a sustained tachycardia of over 100 beats/min during treatment (11 horses) or on day 2 if conversion had not occurred (7 horses). Plasma quinidine concentrations within 1 hour of conversion of AF to sinus rhythm ranged from 1.7 to 7.5 μg/mL (mean, 4.05± 1.6) and ranged from 1.7 to 4.7 μg/mL in 97% of horses. Most horses (92%) with plasma quinidine concentrations > 5 μg/mL exhibited an adverse or toxic effect of quinidine sulfate (clinical or electrocardiographic). There was no statistical association between plasma quinidine concentrations and sustained tachycardia (> 100 beats/min), diarrhea, or colic. Ataxia and upper respiratory tract stridor were significantly associated with plasma quinidine concentrations. In most instances (98%) conversion did not occur while toxic or adverse effects of quinidine sulfate were present or when plasma quinidine concentrations were > 5 μg/mL.     

Treatment of equine intestinal constipation with integrated traditional Chinese and western veterinary medicine

In April 2011, horses at Nanjing Racecourse were accidentally overdosed with ivermectin deworming powder, mixed into the feed. After 3 days of medication, most of the horses ate feed only and reduced their hay intake significantly. On Days 5–6, 3 Mestizo horses showed discomfort, no appetite, sweating, abdominal enlargement, restlessness, whinnying, pawing the ground and no defaecation. Of the other horses, 4 showed abnormal sweating. Toxic atony of the large intestine was diagnosed. During the initial treatment process, only glucose saline injection was used to strengthen cardiac function and sustain the balance of body fluid. It was given in an enema with liquid paraffin, or drenched with magnesium sulfate and liquid paraffin. However, these treatments failed to cure the horses. One of the most seriously affected horses died the next morning. Then, analgin was injected i.m. and vitamin B₁ was injected immediately into bilateral Guanyuanshu acupoints. At the same time, a decoction of Costus root‐Areca reed‐Rhubarb‐Mirabilite powder (CARMP) was given by gavage immediately. Liquorice root was decocted and then the decoction was fed mixed into the feed, at the dosage of 200–300 g per horse, s.i.d., for 3–5 days. One horse died before the integrated treatment but all others horses recovered. Two additional cases were cured with similar treatment.     

Effect of experimentally induced endotoxemia on serum interleukin-6 activity in horses.

A study was conducted to determine whether serum interleukin-6 (IL-6) activity increased in horses during experimentally induced endotoxemia and whether serum IL-6 activity correlated to changes in clinical or laboratory data. Six clinically normal horses were given endotoxin IV (30 ng/kg of body weight) in 0.9% NaCl solution over 1 hour. Five of these and 1 additional horse served as controls and were given only 0.9% NaCl solution. Venous blood, for determination of serum IL-6 activity and WBC count, was collected before and at various times through 8 hours after the start of endotoxin or NaCl infusion. Rectal temperature and heart and respiratory rates were recorded throughout the study period. Serum IL-6 activity was determined by bioassay of proliferation of the B13.29 clone B.9 hybridoma cell line. From 1.5 through 5 hours after start of the infusion, serum IL-6 activity was significantly (P less than 0.05) increased in horses given endotoxin. Mean peak serum IL-6 activity was observed between 3 and 4 hours. In response to endotoxin infusion, horses became lethargic, tachycardic, and febrile. Leukopenia developed by 1 hour, followed by leukocytosis at 8 hours. Significant (P less than 0.05) positive association and linear correlation were apparent between mean serum IL-6 activity and mean rectal temperature in the group of horses that were given endotoxin. Changes from baseline were not evident in any of the clinical or laboratory values in horses given only NaCl solution.