Trema micrantha toxicity in horses in Brazil

After ingesting green leaves of T. micrantha, 2 horses showed apathy, locomotor deficit, blindness, recumbency, paddling, coma and death. The main gross findings were scattered haemorrhages, enhanced lobular pattern of the liver, and cerebral oedema. Histological changes included disseminated haemorrhages, massive hepatocellular necrosis, neuronal degeneration, Alzheimer type II astrocytes and cerebral perivascular oedema. Clinicopathological findings which were comparable with those observed in Trema micrantha poisoned ruminants, associated with epidemiological evidence suggested the diagnosis.Trema micrantha poisoning should be evaluated as a possible cause in the diagnosis of equine hepatopathy and occasional secondary encephalopathy.     

Plants poisonous to horses in Europe

Poisoning of horses by plants is a relatively common veterinary problem and may occur when the fresh plant is ingested in pasture or when the plant contaminates hay, silage and feed. In Europe, horses are particularly at risk of poisoning by Cynoglossum officinale (houndstongue), Datura stramonium (jimson weed), Hypericum perforatum (St. John's wort), Nerium oleander (oleander), Pteridium aquilinum (bracken fern), Robinia pseudoacacia (black locust), Senecio jacobaea (tansy ragwort), Taxus baccata (European yew) and Thuja occidentalis (white cedar). For each of these poisonous plants the information given in this review includes plant distribution, conditions of poisoning, toxic active principles and clinical signs.     

Problems associated with perioperative morphine in horses: a retrospective case analysis

Objective To identify the incidence of adverse effects caused by morphine 100–170 µg kg^?1 administration during surgery in horses. Design Retrospective case record analysis (1996–2000). Animals Eighty‐four healthy (ASA 1 or 2) horses, mean age 5.5 ± 3.1 (SD) years (2 months to 16 years), mean weight 524 ± 14 kg (100–950). Methods Physiological data and evidence of complications were collected from the anaesthetic records of all animals anaesthetized with romifidine, ketamine, diazepam and halothane and undergoing laryngeal surgery or orchiectomy at the Royal (Dick) School of Veterinary Studies. Cases were divided into those receiving (group M+; n = 18) and those not receiving morphine (M?; n = 29), and the data compared. Values for heart and respiratory rate and mean arterial pressure were compared at 15‐minute intervals between 30 and 120 minutes after induction using anova for repeated measures. The incidence of intraoperative problems was compared using Fisher's exact test. Recovery scores were compared using Student's unpaired t‐test. The records of a further 37 horses undergoing umbilical herniorrhaphy (n = 5), arthroscopy (n = 29) or tarsal arthrodesis (n = 3) were also studied but not analysed statistically due to disparate treatment distribution. Results There were no significant differences between the M+ and M? groups. The incidence of post‐operative complications such as box‐walking and colic were similar in each group. Conclusions Morphine doses of 100–170 µg kg^?1 do not increase the risk of problems when used to provide perioperative analgesia in horses anaesthetized with romifidine, ketamine, diazepam and halothane. Clinical relevance Morphine provides an acceptable and relatively inexpensive way to provide perioperative analgesia in horses.     

Welfare issues related to transport and handling of both trained and unhandled horses and ponies

Dehydration and increased risk of respiratory problems are common outcomes of transport, and both appear to be related to journey duration, emotional effects, such as fear, and challenging environmental conditions. Welfare may be improved by familiarising equines with transport vehicles and loading procedures before travel starts, and by providing thermally comfortable and well ventilated conditions during the journey. For long road journeys, rest breaks with drinking water should be given. Both trained and unhandled animals should have sufficient space and freedom to adjust their posture and to lower their heads, but maximum safe space allowances are unknown. Mares and foals should be transported together. Injury during transport is relatively common, particularly in groups of horses travelling to slaughter, and is usually associated with driver error, internal fittings and vehicle type or design, but also with mixing of animals of different sex and weight leading to fighting. There needs to be better training and monitoring to prevent such avoidable risks to horse welfare. There is also a need for more research into appropriate prophylaxis and post transport therapy as knowledge of accumulated stress and depressed immune function following prolonged and repeated transport is poorly understood.     

Long-established and emerging pesticide poisoning in horses

Poisoning is a frequent problem in domestic animals. Horses are the third most commonly affected species and pesticides are one of the main causes of toxicosis. Here within are reviewed the most frequent toxicoses where it emerges that the main causes are misuse and accidental exposure. Rodenticides, acetylcholinesterase insecticides followed by herbicides are the main cause of toxicosis and effects of emerging chemicals are being reported. Metaldehyde is still a problem, together with methiocarb. No information has been reported on poisoning with pesticide mixtures.     

Exercising arrhythmias and sudden cardiac death in horses: Review of the literature and comparative aspects

Arrhythmias are common in equine athletes during and immediately after exercise. Many of these rhythm variations are not clinically relevant. In horses, a link between different exercising arrhythmias and poor performance or between exercising arrhythmias and sudden cardiac death (SCD) is strongly suspected but not fully understood or proven. SCD during races or competitions is rare, but has catastrophic consequences for the safety of the human partner and public perceptions of welfare during equestrian sports. This review summarises current knowledge of equine exercise arrhythmias and their implications in SCD and compares existing principles and recommendations for equine subjects with those for human athletes.     

Factors associated with mortality and morbidity in small intestinal volvulus in horses

OBJECTIVE: To determine historical, physical, and clinical factors that may affect morbidity and mortality in horses with small intestinal volvulus unrelated to other causes (e.g., incarceration, lipoma, etc.). STUDY DESIGN: Retrospective study. ANIMALS: Client-owned horses (115), aged 1 month to 21 years. Methods: Data were obtained from medical records, identified by computer search and manual review. Continuous variables were compared between affected and non-affected horses with Mann-Whitney U-tests and non-continuous variables with Fisher's exact test (2 x 2 tables) or chi(2)-tests (larger tables). Stepwise logistic regression analysis was used to develop a multivariable model of the risk factors, taking account of confounding and interaction. RESULTS: Eighty percent of horses recovered from surgery survived to hospital discharge. Neither age, breed, nor sex was related to mortality. Survivors had a significantly lower heart rate, shorter capillary refill time, and better mucous membrane color. Variables associated with worsening cardiovascular status, increased hemoconcentration, and exudation of cells and protein into peritoneal fluid were significantly associated with non-survival. After recovery from surgery, the most serious complication was colic, which was significantly associated with non-survival (P=.028) as was a second celiotomy (P<.01). Both of these complications were associated with a jejunocecostomy during the first surgery. CONCLUSIONS: Significant differences in the clinical and clinicopathologic signs were identified between survivors and non-survivors. CLINICAL RELEVANCE: These findings can be used to make a scientific assessment of prognosis in the pre-operative, operative, and post-operative management of horses with small intestinal volvulus.     

Fescue‐associated oedema of horses grazing on endophyte‐inoculated tall fescue grass (Festuca arundinacea) pastures

A new form of toxicity called equine fescue oedema is described. The clinical signs included inappetence, depression, and subcutaneous oedema of the head, neck, chest and abdomen. Affected horses had very low plasma albumin values. The toxicity affected 48 of 56 horses on six farms in different states of Australia, and 4 horses have died. All horses were grazing pastures that had been sown with varieties of Mediterranean tall fescue (Festuca arundinacea) that carry the endophyte known as Max P or Max Q. It is proposed that a pyrrolizidine alkaloid, N‐acetyl norloline, which is produced by the Max P endophyte, may be responsible for this new toxicity in horses.     

Plantar fasciitis in 19 endurance horses: Diagnosis,treatment and follow-up

Lesions of the peritendinous–periligamentous soft tissues of the tarsus (plantar fasciitis) commonly result in a curb-like appearance and are considered overrepresented in Standardbred racehorses; however, plantar fasciitis is also quite common in endurance horses. Nineteen endurance horses of different ages (median: 7 years; range: 3–13) and athletic activity level comprising a total number of 25 plantar fasciitis cases were described in this study. In nine cases, injury developed during a training session, and in 16 cases, it developed during competition. In 18 cases, there was swelling, heat and pain on palpation, and in six cases, only swelling was detected. Eight cases were not lame at the time of examination, while in 17 cases, lameness ranged from grades 1–3 on the American Association of Equine Practitioners modified grading scale. The degree of swelling was significantly related to the lameness grade. Ultrasonography revealed differing amounts of thickening of the plantar fascia plantar to the superficial digital flexor tendon and peritendinous–periligamentous oedema of heterogeneous appearance. Horses were treated conservatively with several combinations of rest, controlled exercise, ice-therapy, corticosteroids, local application of working counterirritants and therapeutic shoeing. Seventeen of 25 cases (68%) did not develop re-injury after treatment and rehabilitation, whilst eight of 25 (32%) developed one or more re-injury/injuries. Overall, 21 of 25 cases (84%) returned to the previous or a higher level of competition; in one case (4%), the injury was the cause of retirement from athletic activity. Plantar fasciitis can be considered a sport-related injury in endurance horses of all ages and athletic activity level. Re-injury rate is low; however, adequate rest and rehabilitation protocols are important. Plantar fasciitis rarely leads to retirement from athletic activity, but it can result in 2–5 months out of training and competition.     

Hepatoencephalopathy syndrome due to Cassia occidentalis (Leguminosae,Caesalpinioideae) seed ingestion in horses

Cassia occidentalis is a bush from the Leguminosae family, subfamily Caesalpinoideae, and is a toxic plant of veterinary interest due to the occasional contamination of animal rations. This report describes the clinical and histopathological findings of an outbreak of C. occidentalis poisoning in horses. Twenty mares were poisoned after consuming ground corn contaminated with 8% of C. occidentalis seeds. Of the 20 animals affected, 12 died: 8 mares were found dead, 2 died 6 h after the onset of clinical signs compatible with hepatic encephalopathy and the 2 other animals were subjected to euthanasia 12 h after the onset of the clinical signs. The remaining 8 mares presented with mild depression and decreased appetite, but improved with treatment and no clinical sequelae were observed. In 6 animals that underwent a necropsy, an enhanced hepatic lobular pattern was noted and within the large intestine, a large number of seeds were consistently observed. Hepatocellular pericentrolobular necrosis and cerebral oedema were the main histological findings. In one mare, there was mild multifocal semimembranosus rhabdomyocytic necrosis and haemorrhage. Seeds collected from intestinal contents and sifted from the culpable feedstuff were planted. Examination of the leaves, flowers, fruits and seeds of the resultant plants identified C. occidentalis. Horses poisoned by C. occidentalis seeds demonstrate clinical signs associated with hepatoencephalopathy and frequently die suddenly. Lesions primarily involve the liver and secondarily, the central nervous system. Cassia occidentalis poisoning should be considered a differential diagnosis in horses with hepatoencephalopathy and special caution should be taken with horse rations to avoid contamination with seeds of this toxic plant.     

Management and complications associated with treatment of cervical oesophageal perforations in horses

Six horses were evaluated for colic and anorexia, choke or suspected oesophageal rupture with and without tracheal laceration. Clinical findings were variable, but a painful ventral neck swelling was noted in all cases. Two of the horses had signs of dehydration and sepsis. Additional findings included evidence of previous trauma over the trachea and oesophagus, ventral neck abscessation, choke and aspiration pneumonia. A diagnosis of oesophageal perforation was made using endoscopy. Two horses were subjected to euthanasia without treatment. All horses where treatment was attempted received debridement of the oesophageal perforation and surrounding tissues with or without surgical closure of the oesophageal defect. Other therapies included broad spectrum antimicrobials, anti‐inflammatory drugs, fluid and nutritional support as well as additional therapeutics for sepsis and individual complications. Complications included diverticulum formation, thrombophlebitis, diarrhoea, laryngeal hemiplegia, azotaemia, aspiration pneumonia, oesophageal obstruction, weight loss and laminitis. All 4 treated horses recovered from the oesophageal perforation and are able to eat a normal diet. Two of the 4 horses have had infrequent episodes of recurrent choke. Oesophageal rupture should be considered as a differential diagnosis for horses with a painful swelling of the ventral neck. With surgical debridement and adequate supportive care, oesophageal perforation cases can have a fair to good long‐term survival, although chronic complications can occur, therapy is prolonged, and a significant economic commitment is required.     

Detection and genetic characterisation of vanA‐containing Enterococcus strains in healthy Lusitano horses

Lusitano horses were investigated in order to detect the presence of vancomycin‐resistant enterococci. vanA isolates showed high level vancomycin (Minimum inhibitory concentration; MIC ≥128 mg/l) and teicoplanin resistance (MIC 64 mg/l), as well as resistance to ciprofloxacin, erythromycin and tetracycline. The tet(L) and erm(B) genes, associated with tetracycline and erythromycin resistance, respectively, were found in all vanA isolates. The intestinal tract of Lusitano horses can be a potential reservoir for vanA‐containing enterococci.     

A cross-sectional study of geriatric horses in the United Kingdom. Part 1: Demographics and management practices

Reasons for performing study: With growing numbers of aged horses, geriatric medicine is becoming increasingly important in equine veterinary practice; however, there is a paucity of information on the UK equine geriatric population. Objectives: To describe the demographic characteristics of the equine geriatric population and to assess management practices undertaken by owners of geriatric horses (aged ≥15 years). Methods: A cross‐sectional study was conducted, surveying a randomly selected sample of veterinary registered owners with horses aged ≥15 years, using a self‐administered postal questionnaire. Results: Horses aged ≥15 years represented 29% of the equine population in the study area. The response rate to the questionnaire survey was 80.2%. Management practices were similar to those previously described for the general equine population. However, the level of exercise and feeding practices changed significantly with increasing age. A summary of the demographic characteristics, feeding and management of horses in a sample of the geriatric equine population is presented. Conclusions and potential relevance: The management of geriatric horses has a direct effect on their health and welfare and this study has provided valuable information on the demographics and management of geriatric horses and ponies in the UK. The information can be used to form targeted owner education programmes for geriatric health and should aid in the investigation and prevention of disease.     

Nigropallidal encephalomalacia in horses grazing Rhaponticum repens (creeping knapweed)

Nigropallidal encephalomalacia was diagnosed in two horses in northern Victoria that had a history of long-term pasture access to a dense growth of Rhaponticum repens. The region in which the affected horses lived had received well above average rainfall for several months preceding the poisoning. Affected horses had sudden onset of subcutaneous oedema of the head, impaired prehension and mastication, dullness, lethargy and repeated chewing-like jaw movements. Diagnosis was confirmed at necropsy, with characteristic malacic lesions in the substantia nigra and globus pallidus of the brain. This is the first documented case of nigropallidal encephalomalacia in Australian horses associated with R. repens.     

Infectious disease surveillance of apparently healthy horses at a multi-day show using a novel nanoscale real-time PCR panel

In the United States, horses are used for a variety of purposes including recreation, exhibition, and racing. As farm, performance, and companion animals, horses are a unique species from a zoonotic disease risk perspective, and the risks of subclinical infections spreading among horses can pose challenges. Using a nanoscale real-time PCR platform, we investigated the prevalence of 14 enteric pathogens, 11 Escherichia coli genes, and 9 respiratory pathogens in fecal samples from 97 apparently healthy horses at a multi-day horse event. In addition, sugar flotation test was performed for fecal parasites. E. coli f17 was commonly detected, prevalent in 59% of horses, followed closely by Streptococcus equi subsp. zooepidemicus (55%). Additional pathogens recognized included betacoronavirus, Campylobacter jejuni, Cryptosporidium sp., E. coli O157, equine adenovirus 1, equine rhinitis B virus, and others. The use of PCR data may overestimate the true prevalence of these pathogens but provides a sensitive overview of common pathogens present in healthy horses. Our results prompt the continued need for practical biosecurity measures at horse shows, both to protect individuals interacting with these horses and to minimize transmission among horses.