Toxicology in horses involves the study of substances that can cause adverse effects when introduced to the equine body. This field examines the sources, mechanisms, and outcomes of exposure to toxic agents, which may include plants, chemicals, drugs, and environmental toxins. Understanding toxicology is essential for identifying and managing poisoning cases in horses. Research in this area often focuses on the identification of toxic compounds, their metabolic pathways, and the clinical symptoms associated with exposure. This page compiles peer-reviewed research studies and scholarly articles that explore the detection, effects, and management of toxic substances in equine health.
A 3-year-old Thoroughbred gelding was examined because of clinical signs of pneumonia and shock. Mucous membrane petechiation and ventral edema were observed and considered to be a result of vasculitis. Epidermal necrosis developed on the distal portions of the limbs. The horse had a persistent high fever that was unresponsive to nonsteroidal anti-inflammatory treatment, and Staphylococcus aureus was isolated from a nasal swab specimen and 2 transtracheal wash fluid samples. Antimicrobial, anti-inflammatory, and supportive treatment resulted in clinical improvement. However, resolution of the ...
So YM, Kwok WH, Yuen SMS, Wong COL, Ho ENM.Despite the recent success in introducing supramolecular solvents (SUPRAS)-based extraction to drug analysis, its application and robustness in day-to-day regular urine testing have yet to be demonstrated. Moreover, the applicability of SUPRAS in equine doping control testing remains unexplored. In this work, we have successfully developed for the first time a simple, rapid, inexpensive, and environmentally friendly SUPRAS extraction method for analyzing 76 prohibited substances of different classes (selective androgen receptor modulators, hypoxia-inducible factor prolyl hydroxylase inhibitors...
Cardillo NN, Villarino NF, Kappmeyer LS, Chung CJ, Suarez CE, Bastos RG.Equine piroplasmosis (EP) is a tick-borne disease of equids caused by the intraerythrocytic apicomplexan parasites Theileria equi, Babesia caballi and the recently identified Theileria haneyi. Acute cases can be severe, with anemia, jaundice, abortion or sudden death. Survivors remain lifelong carriers, serving as reservoirs for tick-borne and iatrogenic transmission. No vaccines are currently available, and control strategies rely heavily on accurate diagnostics and chemotherapeutic intervention. Imidocarb dipropionate (ID) is the current standard of care for both acute treatment and radical ...
Environmental contamination with heavy metals, resulting from industrialization, urbanization, and agricultural intensification, poses serious ecological and health risks. Horses, due to their grazing behavior and close association with human environments, serve as reliable sentinel species for assessing environmental pollution. This study aimed to evaluate the bioaccumulation of heavy metals and trace elements in different biological matrices of horses-blood, hair, hooves, and synovial fluid-and to investigate their relationship with hematological biomarkers as indicators of physiological str...
Dindo S, Tovar-Pascual L, Baldassarro VA, Bucci D, Mislei B, Spinaci M, Ortiz-Rodriguez JM.Nanoplastics (NP) accumulation in biological tissues and their adverse effects on fertility through inflammatory and oxidative stress responses have recently been described as consequences of global plastic pollution. However, little is known about the impact of NP on gametes. This study aimed to assess the internalization of NP and their effects on mature equine spermatozoa. Frozen-thawed ejaculates from five stallions were divided into untreated control (CTR) and samples supplemented with different concentrations (10, 50, 100 and 200 μg/mL) of 30 nm polystyrene NP. At baseline (T0), and a...
Kong FKW, Wong ASY, Cheung RKK, Wan TSM, Ho ENM.In order to control the potential misuse of perfluorocarbons as an oxygen carrier in equine sports, a simple and sensitive method for detecting perfluorocarbons in equine plasma by gas chromatography/tandem mass spectrometry using negative chemical ionization with methane as reagent gas has been developed and fully validated. The method covers seven perfluorocarbons, which are the active components in blood substitute products, and shows good sensitivity and robustness. Limits of detection as low as 0.01 ng/mL could be achieved by the method. To the best of our knowledge, this is the first r...
Gilliam LL.Snakebite envenomation (SBE) in horses can have devastating outcomes. Tissue damage, cardiotoxicity, coagulopathy, and neurotoxicity can be concerns with SBE. Understanding the actions of venom components is important in developing a successful treatment plan. Antivenom is the mainstay of treatment. Long-term deleterious effects can occur including cardiac dysfunction and lameness.
Fritz SA, Charnas S, Ensley S.Blue green algae cyanotoxins have become increasingly more prevalent due to environmental, industrial, and agricultural changes that promote their growth into harmful algal blooms. Animals are usually exposed via water used for drinking or bathing, though specific cases related to equines are very limited. The toxic dose for horses has not been determined, and currently only experimental data in other animals can be relied upon to aid in case interpretation and treatment. Treatment is mostly limited to supportive care, and preventative control methods to limit exposures are more likely to aid ...
Sugimoto K, Nakamura J, Deng D, Hirano E.Indoxyl sulfate (IS) is a dietary metabolite of tryptophan that is produced in the liver. It is a uremic toxin that facilitates the progression of chronic kidney disease (CKD). We previously observed that equine placental extract (ePE) inhibited IS synthesis in an inhibition assay using the liver S9 fraction. Unassigned: This study was designed to investigate the effects of ePE on adenine-induced renal failure in mice at the histological and molecular levels to understand the mechanism of action of ePE. Unassigned: We assessed this effect through biochemical and histological analyses using a...
Costa Kamura BD, Albertino LG, Cavallari RR, Queiroz de Souza L, Rodrigues LT, Barros de Sousa Pereira I, Rocha NS, Takahira RK, Briscola Pereira WA....Africanized crossbred bees (Apis mellifera) originated in Brazil in 1957, and since then, the number of accidents involving humans and animals has significantly increased. Although they are considered clinical emergencies, there are few reports describing the clinical and pathological aspects of bee envenomation in horses. In this context, this report aims to describe the clinical and pathological features of bee toxicity after massive bee envenomation in three horses. The horses were referred to the veterinary hospital the day following the attack, and after clinical and laboratory examinatio...
Machado M, Queiroz-Machado CRR, Queiroz F, Gardner DR, Riet-Correa F.A Mimosa pudica var. unijuga-associated toxicity affecting horses occurred in Araguari, Triângulo Mineiro, Southeast Brazil. Affected horses had gradual hair loss of the mane and tail and endocrine dermatosis after grazing for three months during the dry season on a paddock invaded by the plant. The main histological lesions include compact ortho-keratotic hyperkeratosis and numerous flame follicles. Toxicological analysis by HPLC-UV demonstrated 0.8 mg/g of mimosine in the leaves.
Leppänen V, Mykkänen A.Vipera berus berus is the only venomous snake present in the Nordic countries and cases of envenomation in horses are reported during the warmer months. Little is known about the presentation, treatment and survival of horses with common European adder envenomation. Clinical and laboratory findings, treatment and outcome are reported for 28 horses admitted to Helsinki University Equine Hospital in 2008-2023 due to suspicion of snake bite. Eleven of these horses received antivenom treatment. Other common treatments included non-steroidal anti-inflammatories (22/28), antimicrobials (19/28), intr...
Stegelmeier BL, Davis TZ.Many toxic plants are unpalatable to horses and are not eaten when alternative forage is available. However, when such plants contaminate prepared or baled feed and forage, herd competition and improved palatability can alter acceptance and thereby cause equine plant poisonings. Dehydropyrrolizidine alkaloid-containing plants; cocklebur; Salvia reflexa; kleingrass, switchgrass, and other saponin-containing grasses; jimson weed, black henbane, and other tropane alkaloid-containing plants; lantana; Cassia spp and other myotoxic plants; castor bean; cyanogenic glycoside-containing plants; thiamin...
Marcelino I, Monti G, Cornelissen P, Bassingthwaighte E, Het Lam J, van der Merwe D, van der Poel WHM.Trace minerals are essential for animal health but can also, together with heavy metals, have a negative impact, making their monitoring crucial to assess animal health. These elements were examined through a long-term post-mortem monitoring system based on routine liver sampling for Heck cattle, Konik horses and red deer in place at the Oostvaardersplassen nature reserve in the Netherlands, using data from this system to determine reference intervals and investigate trends in liver trace element concentrations. Throughout the monitoring programme, inductively coupled plasma mass spectrometry ...
Brooks L, Ryan M, McCosham E, Loganathan D.In 2009, levamisole was identified as a source for several aminorex positives reported in postrace equine samples in Canada. Since then, unexplained detections of aminorex continue to be identified in equine samples where there is no evidence to link these detections to a levamisole administration. Previous studies identified a compound named barbarin in some species of plants from the Brassicaceae family and suggested that barbarin may be a possible precursor for aminorex. The objectives of this study were to (1) investigate the link between barbarin and aminorex and (2) identify other biomar...
Aguirre Siliezar K, Datu C, Proia K, Rotstein D, Nemser SM, Tyson GH, Ragsdale JM, Wilkes RP, Baker RE, Carossino M, Del Piero F, Sasaki E, Yant P....A multi-state outbreak of equine botulism occurred between December 2022 and March 2023 in the United States. Follow-up and testing were performed on 42 horses, including 24 that died or were euthanized in the outbreak that affected ~98 horses. Affected horses had all been exposed to the same commercial feed. Clinical signs included progressive muscle weakness and tremors, recumbency, and colic. No significant gross or microscopic abnormalities were observed on autopsy. Feces and gastrointestinal content were tested for various infectious agents, including botulinum toxin; fecal samples from 2...
Zebeli Q, Lindner L, Metzler-Zebeli BU.Grasslands are the cornerstone of horse feeding, used for grazing and to produce roughages and their products. However, improper grassland management hides several threats for equine health. In this context, grasslands contaminated with toxin-producing endophytes are considered an increasing threat for horses in many parts of the world. Endophytes are fungi that may grow in a mutualistic relationship in a range of grasses, including fescue grass and perennial ryegrass, two foliage species commonly found in European and American meadows and pastures. The endophytes produce alkaloids that are hi...
Sakai DM, Ishikawa Y, Im JSY, Zhang S, Reed RA, Quandt JE, Barletta M, Knych HK.Administering large volumes of bupivacaine in the rectus abdominis sheath (RAS) block in horses could cause local anesthetic toxicity. This study aimed to evaluate the pharmacokinetics of 2 mg/kg bupivacaine in RAS blocks and the associated toxicity risk. Six healthy adult horses were sedated with xylazine and received an ultrasound-guided bilateral 2-point RAS block. Plasma samples were collected at baseline and from 5 min to 24 h after the block and analyzed using liquid chromatography-tandem mass spectrometry. A noncompartmental analysis was performed to determine the maximum concentr...
Kabil E, Ural MN, Göktaş EF.Synthetic cannabinoids (SCs) were originally synthesized to advance the understanding of the endocannabinoid system, facilitate disease research, and support the development of novel therapeutic agents. Compared with tetrahydrocannabinol, these compounds exhibit substantially higher psychoactive potency and enhanced receptor-binding affinity. The rapid and continuous evolution of SC derivatives presents significant challenges for analytical laboratories and increases the risk of misuse. Furthermore, SCs may be exploited to alter performance in both human and animal sports. The scarcity of comp...
Villa RE, Azimonti G, Bonos E, Christensen H, Durjava M, Dusemund B, Gehring R, Glandorf B, Kouba M, López-Alonso M, Marcon F, Nebbia C, Pechová A....Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of tea tree oil obtained from leaves and terminal branchlets of (Maiden & Betche) Cheel when used as a sensory additive for all animal species. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that tea tree oil was very unlikely to be of safety concern for long-living and reproductive animals and is of no concern for target species for fattening at the following concentrations in complete feed: 1.1 mg/kg for chickens for f...
Riet-Correa F, Micheloud JF, Machado M, Mendonça FS, Schild AL, Uzal FA, Lemos RAA.The objective of this paper is to review the information on toxic plants for ruminants and horses in South America, a continent in which there are 237 plants known to be toxic for livestock. Predisposing factors for plant toxicity include parts or vegetative state of the plants consumed, sprouting after rains, toxic dose, social facilitation, palatability, hunger, thirst, naivete, ingestion period, susceptibility/resistance, transportation, climatic alterations, and environmental degradation. Toxic plants can be forage or non-forage species. The latter can be invasive plants from other regions...
Sánchez A, Durán G, Cerdas M, Gutiérrez J, Segura Á, Herrera M, Vargas M, Sánchez A, Sánchez P, Solano G, Villalta M, Moscoso E, Umaña D....Recent research suggests that a polygeneric immunogen made from the venoms of the most medically important viperid and elapid snakes in sub-Saharan Africa could elicit a broader antibody response in horses compared to the current EchiTAb-plus-ICP antivenom, especially against neurotoxic elapid venoms. To test this, 25 horses that have been regularly immunized to produce this antivenom were reimmunized with an immunogen containing 22 venoms from various snake species from the genera , , , and both spitting and non-spitting . The plasma collected from these horses was processed using the capryli...
Villa RE, Azimonti G, Bonos E, Christensen H, Durjava M, Dusemund B, Gehring R, Glandorf B, Kouba M, López-Alonso M, Marcon F, Nebbia C, Pechová A....Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of an essential oil from the flowering tops of (L.) Cav. (Spanish type origanum oil) when used as a sensory additive in feed and in water for drinking for all animal species. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the additive under assessment is considered safe up to the maximum use level in complete feed of 15 mg/kg for poultry species, 30 mg/kg for pigs and horses, 20 mg/kg for ruminants, 25 mg/kg for rabbits...
Fernandes CM, Prestes AS, Ianiski LB, Maciel AF, Noro BG, da Silva FD, Vizzotto BS, Botton SA, Schumacher RF, Pereira DIB, Barbosa NV.Pythiosis, caused by Pythium insidiosum, is an infectious and non-transmissible disease affecting horses, dogs, and humans, with no effective drug treatment available. Triazoles are compounds of interest for their potential pharmacological properties against fungi and bacteria. In this study, we synthesized three new triazole compounds (C1, C2, and C3) to assess their in vitro activities against P. insidiosum and their safety on human leukocytes. Susceptibility testing was performed against P. insidiosum isolates (n = 15) to determine the minimum inhibitory concentration (MIC) and minimum ...
Villa RE, Azimonti G, Bonos E, Christensen H, Durjava M, Dusemund B, Gehring R, Glandorf B, Kouba M, López-Alonso M, Marcon F, Nebbia C, Pechová A....Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of patchouli oil from the leaves of Benth. (patchouli oil) when used as a sensory additive in feed and in water for drinking for all animal species. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the additive under assessment is safe up to the maximum use level in complete feed of 7.5 mg/kg for chickens for fattening, laying hens, turkeys for fattening, pigs for fattening, horses, salmonids, shrimps, rabbits, dogs, cats...
Gupta KK, Singh L, Saxena N, Dey S, Kumar R, Kumar S.Equine piroplasmosis is a tick-borne disease that affects horses and is caused by Theileria equi and Babesia caballi. Currently, imidocarb dipropionate is the primary treatment for T. equi infections; however, its application is limited by its potential systemic toxicity. Artemisia annua is widely recognised for its antimalarial properties, whereas Artemisia scoparia has traditionally been used for various medicinal purposes. However, the therapeutic potential of A. scoparia against theileriosis in animals remains largely unknown. Activity-guided fractionation of a methanolic extract of A. sco...
Of the mycotoxicoses caused by molds contaminating grains or their byproducts, leukoencephalomalacia of horses and less frequently aflatoxicosis in cattle have been reported in South America. However, the most important group of mycotoxins in the region are those caused by fungi that infect forages and other types of plants and have regional distribution. In this group, ergotism is important, both caused by Claviceps purpurea infecting grains or by Epichloë coenophiala infecting Schedonorus arundinaceus. Other important mycotoxicoses are those caused by indole-diterpenes produced by Clavicipi...
Ilbeigi K, Mabille D, Roy R, Bundschuh M, Van de Velde E, Hulpia F, Van Calenbergh S, Caljon G.Surra and Dourine are widespread diseases caused by two protozoan parasites Trypanosoma brucei evansi and Trypanosoma brucei equiperdum, respectively. A wide range of animals including camels, horses, cattle and buffaloes are susceptible to infection. These diseases pose a significant socio-economic burden, primarily due to the limited therapeutic options and the complications associated with toxicity and drug resistance, making disease management particularly challenging. This study evaluated the potential of 3'-deoxytubercidin, a previously identified antitrypanosomal nucleoside, as a therap...
