Carpometacarpal Osteoarthritis in Thirty‐Three Horses

Objective— To describe signalment, clinical, and radiographic changes associated with carpometacarpal osteoarthritis (CMC‐OA) and to report long‐term outcome. Study Design— Case series. Animals— Horses (n=33) with CMC‐OA. Methods— Medical records (1992–2007) of horses diagnosed with CMC‐OA were reviewed and signalment, clinical, and radiographic findings retrieved. Owners were contacted for information on the impact of lameness on intended use, response to treatment, progression of lameness, outcome, and owner satisfaction with response to treatment. Results— CMC‐OA identified in 39 limbs, occurred predominantly in middle‐aged and older Quarter Horses and Arabians, and caused severe lameness that prevented normal use. Characteristic swelling was centered over the 2nd metacarpal bone/2nd carpal bone articulation. Radiographic changes consisted of proliferative new bone, narrowed joint space, and subchondral lysis. Of 20 horses with follow‐up, 7 of 14 treated horses were euthanatized within 4 years and 4 of 5 nontreated horses within 3 years. Response to treatment was short lived and considered very poor by most owners. Conclusion— CMC‐OA seemingly occurs primarily in Quarter Horses and Arabians in our region. Response to conservative treatment is very poor and short‐lived with most horses being euthanatized. Clinical Relevance— Conventional treatment methods are unsuccessful for treating CMC‐OA.     

Comparison of Three Drilling Techniques for Carpometacarpal Joint Arthrodesis in Horses

Objective: To evaluate 3 drilling techniques for arthrodesis of the equine carpometacarpal (CMC) joint. Study Design: Experimental study. Sample Population: Cadaveric equine forelimbs (n=15). Methods: Limbs were divided into 3 groups (5 limbs each) to evaluate 3 drilling techniques: (1) use of a 4.5 mm drill bit inserted into the joint through 4 entry points and moved in a fanning motion; (2) a 5.5 mm drill bit inserted through 2 entry points to create 3 nonfanned drill tracts (3 drill technique); and (3) a 4.5 mm drill bit used in a 3 drill technique. The CMC joint was disarticulated after drilling, and cartilage and subchondral bone damage evaluated visually and by gross and microradiographic examination using planimetry. Results: Technique 1 produced significantly more damage of the proximal surface, but significantly less to the subchondral bone of the distal surface. Technique 1 produced the most damage to both the articular cartilage and subchondral bone of the total CMC joint than either of the 3 drill tract techniques; however, the difference between techniques 1 and 2 was not significant. Damage from technique 3 was significantly less than that with techniques 1 or 2. Conclusions: Techniques 1 and 2 produced the most cartilage and subchondral bone damage with technique 2 changes more equally distributed between proximal and distal joint surfaces. Clinical Relevance: Technique 1 (fanning) and 2 (5.5 mm 3 drill tracts) may be preferable to achieve arthrodesis of the CMC joint. Morbidity and efficacy of these arthrodesis techniques need to be evaluated in vivo.     

Autologous Platelet Concentrate as a Treatment for Horses with Refractory Fetlock Osteoarthritis

Osteoarthritis (OA) is one of the most common musculoskeletal pathologies in horses and is a disease capable of halting their athletic career. Clinically, OA can be a difficult problem to deal with, particularly when there is no longer a positive response to corticosteroids or rest. In order to avoid further articular tissue degeneration, which could lead to the loss of the joint function, novel therapies are focusing not only on controlling inflammation and pain but also on tissue healing and repair. Autologous platelet concentrate (PC) growth factors are known to have anabolic and angiogenic properties and a positive effect on synovial epithelium, cartilage, and pain. The aim of this study was to analyze the clinical outcome of horses with OA treated with PC. Selected cases were treated only with PC, and they all belong to the same sport activity. We show here the method for PC preparation, follow-up evaluation, and outcome of 20 cases with refractory OA treated exclusively with autologous PC. After a 1-year follow-up, 80% of patients were able to resume work. According to our results and observations, PC can be used as a safe and low-cost intra-articular therapy for refractory OA in the horse.     

Prevalence of Radiographic Signs of Osteoarthritis in Lusitano Purebred Horses

Radiographic prevalence and correlation of radiographic findings has not been performed in Lusitano Purebred horses. The aim of this study was to (1) evaluate the prevalence of primary osteoarthritis radiographic findings in Lusitano Purebred horses; (2) to assess correlations between radiographic findings in different joints of the same limb and different limbs; and (3) elucidate the effect of age in the radiographic findings. A radiographic protocol of the stifle, tarsi, fetlocks and distal limbs was done in 98 Lusitanos and the classification of the radiographs was performed using a 0-4 scale developed and applied blindly by three veterinarians. The distal interphalangeal, proximal interphalangeal, metacarpophalangeal, metatarsophalangeal, tarsometatarsal, distal intertarsal, proximal intertarsal/, tibiotarsal and femorotibial-patellar joints were evaluated. Most joints presented no abnormal findings or minor abnormal radiographic findings (82.86% grade ≤1). The most affected joint was tarsometatarsal and more severe lesions were found in tarsometatarsal and distal intertarsal. Femorotibial-patellar radiographic changes were rare (2.13%). A strong/moderate correlation was found between contralateral joints with exception hindlimb fetlocks. A moderate correlation was found between fore and hindlimbs for distal limb joints. When analyzing ipsilateral as well as diagonal distal limbs, a strong/moderate correlation was also found. The total score progressed in 0.2 score points per each year of age, revealing that age can be a statistically significant predictor for radiographic changes. Overall, Lusitano horses presented a low prevalence of severe radiographic sings of primary osteoarthritis. Findings in contralateral joints tend to be correlated.     

Autologous Platelet Concentrates as a Treatment of Horses with Osteoarthritis: A Preliminary Pilot Clinical Study

The clinical effect of the intra-articular injection of an autologous platelet concentrate (PC) in four horses with osteoarthritis was evaluated. The degree of lameness and joint effusion and clinical follow-up were recorded. Three injections of PC were performed at 2-week intervals. Horses were evaluated before each injection and two months after the last treatment. Clinical follow-up was conducted for 1 year. Count of platelets, leukocytes, and determination of transforming growth factor beta-1 (TGF-β₁) levels per milliliter PC were performed, as well as leukocyte count, cytology, and protein levels in synovial fluid. PC produced a statistically significant improvement in both the degree of lameness and joint effusion (P < .05). The most marked improvement was observed 2 months after the last treatment and apparently persisted for 8 months. A mean of 250 ± 71.8 × 10⁶ platelets, 8.68 ± 3.78 leukocytes × 10⁶, and 12,515 ± 2,443 pg of TGF-β₁ per milliliter PC were obtained. The evaluated synovial fluid parameters remained between normal values. No adverse clinical signs resulted from this treatment. Despite the seemingly positive effects of this substance, the clinical use of PC cannot be recommended until further studies with higher numbers of cases and longer follow-up can be undertaken.     

Arthrodesis of the Distal Interphalangeal Joint in Two Horses Using Three Parallel 5.5-mm Cortical Screws

The distal interphalangeal joint was successfully arthrodesed in two horses using three parallel 5.5-mm cortical screws and an autogenous cancellous bone graft. The screws were directed from the palmar proximal border of the second phalanx dorso-distally across the joint space and into the third phalanx. The technique was first developed on a normal horse. The second horse, a clinical case, ruptured its deep digital flexor tendon with complete luxation of the distal interphalangeal joint. Bony fusion of the distal interphalangeal joint occurred in both horses, but both also had residual lameness at a walk. Twenty-one months after the arthrodesis procedure, the clinical patient died from complications related to a subsolar abscess in the operated limb.     

Prevalence and Treatment of Tapeworms in Horses

A study was initiated to determine the prevalence of tapeworms in horses in Southern Ontario and to investigate the efficacy of pyrantel pamoate, niclosamide and mebendazole. Fecal samples were taken from 580 horses of various breeds, ages and sexes in 24 locations and Anoplocephala perfoliata was found in 13.6%. This was regarded as a minimum, the true rate being probably significantly higher and the reasons for this are discussed. A brief review of the life cycle and effects of tapeworms in horses and a comparison of two flotation techniques for the diagnosis of A. perfoliata eggs in feces is given.Pyrantel pamoate, niclosamide and mebendazole were compared for efficacy in field and critical trials. In field trials, pyrantel base and niclosamide at 6.6 and 50 mg/kg respectively were found to be effective, but in critical trials their efficacy was poor, 15 and 5.6% respectively. These anthelmintics at these dose rates caused only an elimination of the terminal egg bearing segments and were without significant effect on the entire tapeworm. When pyrantel base was administered at 13.2 and 19.8 mg/kg (twice and three times the therapeutic dose rate for nematodes respectively) the efficacy was 97.8 and 100%. It would appear that pyrantel pamoate administered at 13.2 mg pyrantel base/kg is an effective therapeutic dose for tapeworms in horses. Further dose titration studies are needed for niclosamide. Mebendazole was without effect at up to four (35.2 mg/kg) times the therapeutic dose for nematodes.     

Septic Arthritis of the Distal Interphalangeal Joint in 12 Horses

The medical records of 12 horses with septic arthritis of a distal interphalangeal joint were reviewed to determine clinical features and response to treatment. Sepsis was caused by trauma or an injection that resulted in an open or contaminated distal interphalangeal joint. All horses were severely lame. Treatment included broad-spectrum parenterally administered antimicrobial drugs (ten horses), percutaneous through-and-through joint lavage (eight horses), indwelling drains (three horses), immobilization of the limb in a cast (three horses), intraarticular injection of sodium hyaluronate (one horse), intraarticular injection of antimicrobial drugs (five horses), curettage of the distal phalanx (one horse), and cancellous bone grafting to promote fusion (one horse). Five horses were euthanatized. Ankylosis of the affected joint developed in five horses, four of which are pasture sound. Two horses treated medically are sound although one underwent subsequent palmar digital neurectomy for treatment of navicular syndrome.     

Surgical Treatment of Colic Results in 181 Horses

A retrospective study was performed of 181 horses that underwent an exploratory celiotomy because of acute abdominal disease. Forty-four horses died or were euthanized during surgery. Of the 137 horses that recovered from anesthesia, 72 died of associated diseases or complications, 86 were discharged from the hospital of which 60 survived at least 7 months. Horses with disorders affecting the small intestine had a significantly lower survival rate. Causes of death early in the postoperative period included long bone fracture, shock, ileus, gastric rupture, and peritonitis. After discharge from the hospital, deaths were attributed to colic of unknown cause, malabsorption syndrome, adhesive small bowel obstruction, small and large intestinal volvulus, perforated bowel, and laminitis. Of the 60 horses that were alive at the time of survey, 93.3% had returned to their previous use. A second occurrence of the initial acute abdominal disease was not documented in any horse.     

Polysaccharide Treatment Reduces Gastric Ulceration in Active Horses

Equine gastric ulceration effects condition, performance, and behavior. Prevalence of ulcers in horses can reach 80% to 100%. After reviewing the literature, we propose an oral polysaccharide preparation will be effective in treating equine gastric ulceration. Ten adult horses with gastric ulceration were used to evaluate the clinical efficacy of a polysaccharide gel containing a blend of hyaluronan and schizophyllan for 30 days. Posttreatment gastroscopies were conducted to determine treatment findings, and images were scored. Percent healing was assessed comparing initial images to posttreatment findings. Of the horses treated with the combinational therapy, 90% showed complete resolution and/or improvement in ulcerative areas, increased appetite, weight gain, and positive behavioral changes. This study provides evidence that gastric ulceration in active horses can be successfully treated with a naturally safe and effective polysaccharide blend of hyaluronan and schizophyllan.     

Surgical Treatment of Septic Jugular Thrombophlebitis in Nine Horses

Objective: To report a technique for surgical treatment of septic jugular thrombophlebitis unresponsive to medical treatment. Study Design: Case series. Animals: Horses (n=9) with septic jugular thrombophlebitis unresponsive to medical treatment. Methods: Jugular vein thrombectomy was performed under standing sedation and local anesthesia. The contents of the affected portion of vein were removed by multiple incisions in the vein, with the incisions left open to drain and heal by second intention. Results: The technique was curative in all instances, although 2 horses required a 2nd procedure. One horse required ligation of the linguofacial vein to control postsurgical hemorrhage. Conclusions: The technique is an effective surgical treatment for septic jugular thrombophlebitis unresponsive to medical treatment. Clinical Relevance: Jugular vein thrombectomy is a straightforward technique, and has minimal postoperative complications. It allows expedient and cost‐effective resolution of medically recalcitrant cases of septic jugular thrombophlebitis.     

Surgical Treatment of Sand Colic Results in 40 Horses

A retrospective study of 40 horses that underwent surgical treatment for sand colic was performed. Three horses were euthanatized and one died during surgery. Of the 36 horses that recovered from anesthesia, five died before discharge from the hospital and seven died after discharge. Twenty-four horses survived at least 12 months. Sand impaction of the right dorsal colon was present in 26 horses. In addition to sand impaction, 10 horses also had colonic displacement or volvulus.     

Treatment of Mycotic Rhinitis With Itraconazole in Three Horses

Itraconazole, a third-generation azole, was evaluated for treatment of resistant nasal mycotic infections in horses. Two horses with Aspergillus spp nasal granulomas and 1 horse with Conidiobolus coronatus nasal infection were treated with itraconazole (3 mg/kg PO bid). One of the horses with nasal aspergillosis was also treated by surgical resection of the nasal septum. The treatment time for the horses ranged from 3 to 4.5 months. No adverse effects were noted in any of the horses during the treatment period. Peak and trough serum itraconazole concentrations were < 0.5 μg/mL in all 3 horses. Itraconazole (3 mg/kg PO bid) appears to be effective in the treatment of nasal Aspergillus spp infections in horses because the fungal infection was eliminated in both horses. One horse still had excessive nasal sounds during exercise and was retired from training, whereas the other horse returned to normal. The nasal C. coronatus infection appeared resistant to itraconazole treatment in the affected horse because the granulomas were still present after 4.5 months of treatment.     

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.