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.
Atrial fibrillation in horses: factors associated with response to quinidine sulfate in 77 clinical cases. Seventy-seven horses with atrial fibrillation (AF) were treated orally with quinidine sulfate (QS) at the University of Pennsylvania, School of Veterinary Medicine, Thirty-seven horses (48%) had adverse reactions to QS, the most common of which were nasal mucosal edema, anorexia, colic, and diarrhea. The mean highest daily QS dose was slightly greater in horses showing toxicity (P less than 0.1) and their conversion rate was less (P less than 0.05). A schedule of gradually increasing QS dose was time consuming, costly and not associated with fewer adverse reactions. Horses were compared by the...
Effects of nandrolone phenylpropionate in the horse: (1) resting animal. The effects of 7 weekly injections of the anabolic steroid nandrolone phenylpropionate (400 mg) were investigated in 4 healthy, mature geldings. Measurement of body weight, nitrogen retention and plasma urea failed to demonstrate a consistent anabolic effects. Examination of biopsies from the semitendinosus and biceps femoris muscles showed no alteration in water content or glycogen concentration with treatment. Similarly no changes were found in the activities of 6 muscle enzymes. However, a significant increase in the proportion of fast twitch low oxidative fibres of the biceps femoris was o...
Induction of parturition in the mare with prostaglandin F2 alpha. Thirty-one mares of Quarter Horse and Thoroughbred breeding were utilized in two experiments to evaluate the efficacy of prostaglandin F2 alpha (PGF2 alpha) for induction of equine parturition and to monitor the effects of this treatment on viability of the resulting foals. Three of five mares given 5 mg PGF2 alpha (im) on day 338 of gestation foaled 19.6+/-8.2 hr postinjection. In the second experiment immediately following 3 daily injections of 10 mg estradiol cypionate (ECP) given on days 326, 327 and 328 of gestation, seven mares were infused (iv) with PGF2 alpha at the rate of 1.3 mg/hr f...
The efficacy of ivermectin against Strongyloides westeri in foals. Seven foals naturally infected with Strongyloides westeri were injected intramuscularly with ivermectin at a dosage rate of 200 mcg per kg body weight. No adverse effects to treatment were observed. Weekly faecal egg counts showed a greater than 99 per cent reduction of S. westeri egg output compared with 7 untreated foals during the 21 days following treatment.
Gentamicin toxic nephropathy in horses with disseminated bacterial infection. Three clinical cases of toxic nephropathy in young horses were ascribed to gentamicin toxicity. Criteria for defining gentamicin-induced nephrotoxicosis were a serum urea nitrogen value greater than the pretreatment value or cylindruria, hematuria, and proteinuria in the absence of pyuria and bacteriuria. Recommended doses of gentamicin had been given in all cases. The nephropathy was reversible in 1 case in which the toxicosis was detected early and was treated by volume diuresis and drug withdrawal.
Effects of enkephalins versus opiates on locomotor activity of the horse. The enkephalins are small, pentapeptide neurotransmitter molecules which have reportedly been used in racing horses. In our experiments, D-Ala2-Metenkephalinamide and leucine enkephalin were administered to horses intravenously (IV) and intracisternally (IC). Leucine enkephalin had little effect on locomotor activity by either route at doses of 0.01 mg/Kg or less. Methionine enkephalinamide, an enzyme resistant enkephalin analog, had no significant effect when given IV (0.002 and 0.008 mg/kg). Other experiments involving intracisternal dosing with this long acting form at higher levels (0.005-...
Anthelmintic efficacy of ivermectin given intramuscularly in horses. The anthelmintic activity of ivermectin was evaluated in 18 female horses with naturally acquired parasitic infections. Horses were treated once (IM) with vehicle only (n = 6), 200 microgram/kg of body weight (n = 6), and 300 microgram/kg (n = 6). Efficacy of both dosages of ivermectin was greater than 99% against Gasterophilus spp, 100% against Trichostrongylus axei, Habronema muscae, H majus, and Draschia megastoma, 98% to 99% against adult cyathostomes, 86% to 97% against 4th-stage cyathostomes, and 100% against adult large strongyles. Although ivermectin was incomplete in its activity agai...
Restoration of reproductive capacity of stallions after suppression with exogenous testosterone. Twelve stallions that had been given 0, 50 or 200 micrograms testosterone propionate (TP)/kg body weight every other day for 88 days were examined for the effects of androgen withdrawal on spermatozoal production, seminal quality and libido. Although the lower dosage did not affect most of the traits studied, the higher dosage severely reduced scrotal width, spermatozoal production, the number of sperm per ejaculate, the percentage of progressively motile spermatozoa and the percentage of normal spermatozoa. These adverse effects were found to be largely reversible. By 90 days after the cessat...
Phenylbutazone toxicosis in equidae: a biochemical and pathophysiological study. Toxic effects of phenylbutazone (PBZ) in ponies and horses were studied, using a variety of biochemical, pathophysiologic, and pathologic methods. At dosage levels of 10 to 12 mg/kg of body weight/day for 8 to 10 days, ponies frequently developed clinical signs of toxicosis characterized by hypoproteinemia. Studies using 51CrCl3 demonstrated that PBZ caused a protein-losing gastroenteropathy. The plasma loss was usually associated with gastrointestinal ulceration, but sometimes occurred without obvious lesions in mildly affected animals. Similar studies (8.2 mg/kg/day for 13 days) in Thoroughb...
Clinical toxicosis and erythrocyte cholinesterase inhibition of trichlorfon combined with mebendazole in horses. Thirty adult horses were used to compare the toxicity and cholinesterase (ChE) inhibition of various dosages of a combination anthelmintic, trichlorfon + mebendazole. Single oral doses of up to 5 times the effective dosage (39.7 mg of trichlorfon and 8.8 mg of mebendazole/kg of body weight) did not result in deaths. Horses given a placebo and horses treated at the recommended dosage rate showed few or no side effects, whereas horses given higher dosages showed dosage-related increases in the severity of clinical signs of organophosphate toxicosis. Dosage-related inhibition of erythrocyte ChE a...
Behavioral and cardiorespiratory responses to 4-aminopyridine in healthy awake horses. 4-Aminopyridine was administered in incremental IV doses to healthy horses to evaluate cardiorespiratory and behavioral effects. Doses of 100 micrograms/kg produced apparent sensory discomfort, manifested by wiggling or curling of the lips and tongue, arching or stretching the neck, snorting, squealing, and coughing. At cumulative dosages of 300 to 500 micrograms/kg, muscle tremors, a stilted gait, and signs of excitement occurred. Once signs of excitement occurred, additional administration of 4-aminopyridine resulted in prolonged excitement consisting of severe muscle tremors and exaggerated...
Laryngeal paralysis in Arabian foals associated with oral haloxon administration. Bilateral laryngeal paralysis is described in 5 Arabian and part-Arabian foals aged between 23 and 35 days. Tracheotomies resulted in complete relief of dyspnoea. Two cases showed recovery of abductor function of the right arytenoid cartilage after 3 weeks and one of these cases later recovered left abductor function. Four of the foals were autopsied at various times from one week to 6 months after the onset of respiratory obstruction. Histology of the recurrent laryngeal nerves showed active Wallerian degeneration and loss of nerve fibres in many fascicles in cases affected for one to 2 weeks...
Clinicopathological aspects of imidocarb dipropionate toxicity in horses. Six groups of four adult horses were twice injected intramuscularly at a 24 hour interval with 0, 2, 4, 8, 16 or 32 mg/kg of imidocarb dipropionate (IMDP) and monitored for 21 days. The LD50 of IMDP for 21 days after injection was two doses of 15.99 +/- 1.49 mg/kg with mortalities occurring within six days following the first injection. Increasing levels of IMDP were correlated with increasing rates of morbidity, mortality, local and systemic reactions, increasing levels of blood urea nitrogen, serum aspartate amino transferase, serum sorbitol dehydrogenase, serum creatine phosphokinase, neutr...
Toxic effects of lasalocid in horses. Lasalocid was given to horses in a series of sequentially increasing single oral doses ranging between 5 and 30 mg/kg of body weight, with an appropriate washout period between treatments. One of the 5 horses died after a dosage of 15 mg/kg, 1 of 3 horses died after 21 mg/kg, 1 of 3 horses died after 22 mg/kg, and 1 of 2 horses died after 26 mg/kg. The LD50 of lasalocid for horses was estimated to be 21.5 mg/kg. Monensin was given to horses in a similar manner at dosages of 1, 2, and 3 mg/kg of body weight. One of the 2 horses died after a dosage of 2 mg/kg and 1 horse died after a dosage of 3...
Poisoning in animals due to oral application of iron. With description of a case in a horse. Peroral application of iron salts in various types of anemia was previously considered atoxic. The increased use of iron has, however, led to an increasing number of poisoning in children, taking iron tablets for candy. There have only been reported a few number of spontaneous intoxications in animals, but experimentally it has been possible to produce fatal intoxications in various kinds of animal species. The clinical findings are quite similar in the various animals, starting with vomiting, bloody diarrhoea and metabolic acidosis. If the intoxication is severe, shock and coma may develop, a...
[Use of trichlorfon as an anthelmintic in horses (author’s transl)]. The use of trichlorfon as an anthelmintic in horses has increased since it was combined with mebendazole and febantel, and became commercially available as Telmin-trichlorfon and Rintal-plus respectively. Field studies showed that these combined preparations frequently gave rise to cases of poisoning. Mild to severe colic was observed up to six hours after treatment, diarrhoea and/or anorexia continuing to be present for one to six days after administration. The 'horse weight measurer' introduced by Janssen Pharmaceutica is not sufficiently accurate to prevent overdosage. It is advisable only ...