Topic:Adverse Effects
Adverse effects in horses refer to unintended and potentially harmful outcomes that occur as a result of medical treatment, environmental exposure, or other interventions. These effects can impact various physiological systems and may manifest as behavioral changes, organ dysfunction, or other health-related issues. Monitoring and understanding adverse effects are important for ensuring the safety and well-being of horses, particularly in the context of veterinary medicine and equine management. This page gathers peer-reviewed research studies and scholarly articles that explore the causes, mechanisms, and implications of adverse effects in horses, offering insights into their identification, management, and prevention.
Epidural injection of xylazine for perineal analgesia in horses. Local anesthetics given in the epidural space of a horse may cause hind limb weakness in addition to analgesia. Because alpha 2 agonists given by epidural injection cause sensory blockade without motor effects in human beings and other species, their use in veterinary anesthesia is appealing. This study was designed to examine the effectiveness of xylazine HCl, an alpha 2 agonist commonly used in horses. Xylazine, 0.9% NaCl, and lidocaine were given by epidural injection to horses subjected to perineal electrical stimulation. Administration of xylazine (0.17 mg/kg of body weight, diluted to a ...
[2 cases of colonic pbstipation in ponies, probably as a sequela of a treatment with Taktic]. Within a one-year period two ponies were operated on because of colon impaction. The two ponies had each been treated with Amitraz (Taktik) quite recently. In view of findings reported in the literature, the colon impaction in these two ponies was very likely to have been due to treatment with Taktik.
Detomidine-butorphanol sedation in equine clinical practice. Combinations of detomidine (mean dose rate 13 micrograms/kg) and butorphanol (mean dose rate 26 micrograms/kg) were used to sedate 61 horses for a variety of surgical or diagnostic procedures in general equine practice. Three horses were sedated on more than one occasion. The degree of sedation was graded from 3 to 0 (deep sedation to no effect) and any side effects were recorded. Forty-three per cent of the horses were graded 3, 46 per cent were graded 2, 8 per cent were graded 1 and 3 per cent were graded 0. Bradycardia and ataxia were the major side effects. The combination was judged to be...
Combined use of detomidine with opiates in the horse. The effects of administration of one of four opiates (pethidine 1 mg/kg bodyweight (bwt), morphine 0.1 mg/kg bwt, methadone 0.1 mg/kg bwt, and butorphanol 0.05 mg/kg bwt) given intravenously to horses and ponies already sedated with detomidine (10 micrograms/kg bwt) were investigated. Behavioural, cardiovascular and respiratory effects of the combinations were compared with those occurring with detomidine alone. Addition of the opiate increased the apparent sedation and decreased the response of the animal to external stimuli. At doses used, butorphanol produced the most reliable response. Sid...
Cardiorespiratory and sedative effects of a combination of acepromazine, xylazine and methadone in the horse. Cardiorespiratory and sedative effects of a combination of acepromazine, xylazine and methadone were studied in the horse. Acepromazine and xylazine produced cardiovascular effects whereas methadone mainly affected respiratory rate. Decreases in heart rate, arterial blood pressure and respiratory rate were seen. Sedation was superior to that of acepromazine, xylazine or a combination of these. No serious side effects were seen.
Detomidine (Domosedan) in foals: sedative and analgesic effects. Detomidine was administered twice to six foals (14 to 94 days old) using three different doses (10, 20 and 40 micrograms/kg bodyweight intravenously) in a double blind trial. Sedation, analgesia, heart rate and clinically observed side-effects were recorded. Detomidine showed strong sedative effects at all doses tested. Sedation deepened very little by increasing the dose from 10 to 40 micrograms/kg bodyweight, but the duration of the effect was longer. Analgesia was considered good with the largest dose (40 micrograms/kg), and moderate or non-existent with the lower doses. Detomidine caused a...
Hypovolemia, hyperosmolality, and acidosis associated with intraperitoneal infusion of nitrofurazone solution in healthy horses. Nitrofurazone solution containing 0.2% nitrofurazone and 99.8% polyethylene glycol was given to 4 healthy horses (2 L in 2 L of lactated Ringer solution, intraperitoneally). Horses developed hypovolemia, hyperosmolality, and mixed respiratory and metabolic acidosis. These changes were largely attributable to polyethylene glycol, but a contribution of nitrofurazone cannot be excluded. Intraperitoneal infusion of nitrofurazone solution in horses is contraindicated.
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 h...
The effect of detomidine (Domosedan) on the maintenance of equine pregnancy and foetal development: ten cases. Detomidine was administered throughout 10 pregnancies in eight mares. An intravenous injection of 20 micrograms/kg body weight was given weekly from Day 14 to Day 60 of gestation and thereafter every four weeks until parturition. One mare suffered torsion of the large colon and was destroyed on Day 86; the foetus was normally developed. A further mare aborted at 167 days. The remaining eight pregnancies continued to full term. One foal was delivered by caesarean section because of torticollis and, of the seven foals born spontaneously, one had bilateral upward patellar fixation at one month ol...
Adverse reaction to procaine penicillin G in horses. Adverse reactions to intramuscular injections of procaine penicillin G are reported in 11 horses, five of which died. The clinical findings are presented and suggest central nervous involvement in most cases. Post mortem findings in one horse were consistent with anaphylaxis whereas in other cases the clinical findings, duration of treatment, speed of onset and subsequent completion of treatment supports diagnosis of an acute procaine toxicity syndrome.
Horse pill (“bute”) hemorrhage. Phenylbutazone (PBZ) is a nonsteroidal antiinflammatory drug (NSAID) that is not commonly prescribed due to the high incidence of serious adverse reactions. However, it is still used extensively in equine medicine, and is readily available to those employed in the care and management of horses. Such persons may take the drug indiscriminately, without medical supervision. We present a 33-year-old male race horse track worker who took phenylbutazone horse pills for a chronic toothache and subsequently suffered a major hemorrhage from a gastric ulcer. Human use of phenylbutazone horse pills shoul...
Severe Synovitis in Two Horses due to the Use of Irrigating Solutions Containing Methanol and Formaldehyde. Two horses were examined because of chronic lameness, which followed arthroscopy in one case, and tendon sheath lavage in a second case. Clinical investigations linked both cases to the use of irrigating fluids containing preservatives. The clinical signs were reproduced in a Shetland pony by injection and lavage of the carpal joints with the same fluid. Lameness was slow in onset and accompanied by profound periarticular fibrosis. Postmortem examination confirmed the presence of a severe, erosive, noninfectious arthritis that may have an immune-mediated component. Clinicians should read produ...
Sudden and unexpected death in horses and ponies: an analysis of 200 cases. An analysis was made of the causes of death in horses and ponies over one year of age which died suddenly (Group 1) or were found dead but were considered normal when last seen (Group 2). There were 49 animals in Group 1. Thoroughbreds were overrepresented, but there were no ponies in this group. No cause of death was found in 30.6 per cent of cases and 16.3 per cent died from each of the following causes: haemorrhage in the respiratory system, central nervous system, and adverse drug reactions. Cardiovascular lesions were the cause of death in 14.4 per cent and the remaining 3.1 per cent had ...
Chronic flunixin meglumine therapy in foals. Effects of a therapeutic dose of flunixin meglumine on gastric mucosa of horse foals were determined by endoscopy, double-contrast radiography, and gross and histologic examinations. Foals were administered 1.1 mg of flunixin meglumine/kg of body weight, PO/day for 30 days in an encapsulated form that was divided into 2 doses/day (group 1; n = 3) or by IM injection once a day (group 2; n = 7). Three control foals (group 3; n = 3) were administered capsules (n = 1) containing dextrose powder or IM injections (n = 2) of vehicle solution without flunixin meglumine. All 3 groups-1 foals given flun...
Use of erythromycin-rifampin combination in treatment of Rhodococcus equi pneumonia. The selection of lipid-soluble antibiotics capable of intracellular penetration is considered critical for the successful treatment of Rhodococcus equi pneumonia and lung abscesses in foals. Two such antibiotics: erythromycin (25 mg kg-1, three times daily) and rifampin (5 mg kg-1 twice daily) have been used in combination for this purpose at the University of Florida since 1981. Positive evidence of R. equi was present on culture of tracheal aspirates in 57 foals, most of which exhibited radiographic evidence of extensive lung abscessation. The duration of therapy ranged from 4 to 9 weeks. Mi...
Physiological, biochemical and haematological effects on horses of a phenylbutazone paste. Five matched pairs of horses were used to investigate the biochemical, haematological and general clinical effects of a new dosage schedule of a phenylbutazone paste administered under controlled feeding conditions. One group of horses received a loading dose (8.8 mg/kg) on day 1, followed by doses of 3.3 mg/kg daily on days 2 to 8, 10 and 12 with no treatment on days 9 and 11. The second group received equivalent doses of a placebo paste. Bodyweight, skin temperature, respiratory rate, glutamate dehydrogenase activity, packed cell volume, mean corpuscular volume and neutrophil count were alte...
Immune-mediated hemolytic anemia induced by penicillin in horses. Three horses developed severe, immune-mediated hemolytic anemia after treatment with penicillin. The horses had positive direct antiglobulin (Coombs) tests and high titers of IgG antibody that agglutinated penicillin-coated equine red cells. Two of the horses were tested for antibodies to autologous red cell antigens; autoantibodies were not present. Titers of antipenicillin antibody decreased after penicillin was discontinued but IgG antibody was detectable months after recovery. One of the horses was challenged with penicillin; antibody titer increased slightly, but anemia did not develop. A...
Adverse drug reactions in the horse. Adverse drug reactions occasionally occur in the horse. The majority can be anticipated and avoided. The practicing veterinarian should understand the various types of adverse reactions as well as their mechanisms so that should such a reaction occur, the practitioner can promptly recognize the problem and institute corrective measures.
Investigation into the use of narcotic antagonists in the treatment of a stereotypic behavior pattern (crib-biting) in the horse. Crib-biting in horses is a repetitive behavior pattern which may involve the activation of both narcotic receptors and dopamine receptors in the CNS. Crib-biting frequency, determined in 7 nontreated horses under controlled conditions, was usually linear for many hours and ranged from 0.3 to 14.9 bites/min. Intravenous or IM injections of narcotic antagonists decreased these rates to almost zero by about 20 minutes after the injection was given. The duration of the response to a single injection ranged from 20 minutes for naloxone to 4 hours or more for nalmefene and diprenorphine. Effective d...
Effects of xylazine on equine intestinal vascular resistance, motility, compliance, and oxygen consumption. Isolated jejunal segments were perfused at a constant blood flow rate to determine simultaneously the effects of xylazine on intestinal vascular resistance, motility, compliance, and oxygen consumption in 12 anesthetized ponies. Xylazine was infused into the artery perfusing the intestinal segment (group 1), or into the jugular vein as a single IV bolus (group 2), or 3 times as IV boluses repeated at 10-minute intervals (group 3). Dose-response curves in group 1 indicated a biphasic response to the drug with vasoconstriction, increased motility, and increased oxygen consumption at lower doses ...
[The clinical pharmacology of glycerol guaiacolate ether in the horse–a review]. The physical and chemical properties, administration, biotransformation, pharmacological effects, clinical applications, side-effects, toxicity and contraindications of glyceryl guaiacolate ether in the horse are reviewed.