Topic:Allergies
Allergies in horses are immune-mediated responses to environmental antigens, such as pollen, dust, mold, food, or insect bites, that result in hypersensitivity reactions. These reactions can manifest as respiratory issues, skin conditions, or gastrointestinal disturbances, impacting the horse's overall health and performance. Common allergic conditions in horses include recurrent airway obstruction (RAO), urticaria, and insect bite hypersensitivity. Understanding the underlying mechanisms of equine allergies is crucial for developing effective management and treatment strategies. This page compiles peer-reviewed research studies and scholarly articles that explore the pathophysiology, diagnosis, and management of allergies in horses, as well as their impact on equine welfare and performance.
Distribution of substance P binding sites in equine airways. Autoradiography with [125I]-Bolton Hunter substance P ([I]-BHSP) was used to detect substance P binding sites in the equine lung. Specific [I]-BHSP binding sites were very dense over small bronchial vessels, tracheobronchial glands and airway epithelium in large and small airways. The density of [I]-BHSP binding sites over airway smooth muscle was much lower than in the preceding tissues. Competition with an excess of either a specific neurokinin 1 receptor agonist, or a specific neurokinin 2 receptor agonist indicated that most specific [I]-BHSP binding sites in the equine lung represent neur...
Treatment of Culicoides hypersensitive horses with high-dose n-3 fatty acids: a double-blinded crossover study. In this double-blinded crossover study the clinical efficacy of high dose α-linolenic acid (linseed oil) for the treatment of Culicoides spp. hypersensitivity was evaluated. Seventeen privately owned horses from north Florida, USA completed the 18-week study. Criteria for inclusion included negative dermatophyte cultures, negative skin scrapes, failure to respond to ivermectin treatment, compatible clinical signs, positive skin test to Culicoides spp.antigen and a history of seasonal pruritus consistent with Culicoides spp. hypersensitivity. Horses were randomized and each horse's feed was su...
Cytologic examination of specimens obtained by means of tracheal washes performed before and after high-speed treadmill exercise in horses with a history of poor performance. To evaluate results of cytologic examination of specimens obtained by means of tracheal washes (TW) in 42 horses with a history of poor performance. Methods: Cross-sectional case series. Methods: 42 horses with a history of poor performance. Methods: A TW was performed via endoscopy before and after horses exercised on a high-speed treadmill, and specimens were evaluated microscopically and graded. Results: Ten (24%) horses were considered to be clinically normal before and after exercise. Pulmonary hemorrhage was diagnosed in 8 (19%) horses. One horse had evidence of exercise-induced pulmonar...
Asthma and allergy in New Zealand farmers. To examine the prevalence of symptoms of asthma and allergy in different farming groups in New Zealand. Methods: A postal questionnaire was sent to a random sample of 2,500 farmers throughout New Zealand. Results: The response rate was 77% (1,706 of 2,203 eligibles). The 12-month period prevalence of current asthma was 11.8% overall, compared with 15% in the general population. Asthma prevalence was higher for horse breeders/groomers (16.5%), pig farmers (18.2%), poultry farmers (17.4%), and those working with oats (17.4%). Asthma was also significantly elevated among those working with cleani...
Studies on pulmonary and systemic Aspergillus fumigatus-specific IgE and IgG antibodies in horses affected with chronic obstructive pulmonary disease (COPD). Inhalant exposure to Aspergillus fumigatus (Asp. f.) antigens induces marked inflammatory and immunological alterations in the lungs of horses affected with chronic obstructive pulmonary disease (COPD). In this study we investigated the role of specific allergen(s) present in Asp. f. on systemic and pulmonary IgE and IgG responses in control and COPD-affected horses, using an enzyme-linked immunosorbent assay (ELISA) and immunoblotting techniques. Compared with controls, horses affected with COPD had significantly higher levels of BALF IgE and IgG to somatic Asp. f. antigens as well as to the ...
Inhibition of antigen-induced cutaneous responses of ponies with insect hypersensitivity by the histamine-1 receptor antagonist chlorpheniramine. A whole-body extract of Culicoides impunctatus induced a biphasic increase in oedema formation in ponies with insect hypersensitivity, with maxima after one and eight hours. The Culicoides antigen did not induce similar responses in ponies with no previous history of the disease. In insect-hypersensitive ponies the local administration of chlorpheniramine (12 micrograms) completely inhibited oedema formation in response to histamine (0.04 microgram) and to Culicoides antigen (0.5 microgram) at one hour, and the response to Culicoides antigen at eight hours was inhibited by 63 per cent. Chlorph...
Inhaled leukotrienes cause bronchoconstriction and neutrophil accumulation in horses. Leukotrienes have been shown to mimic many of the pathophysiological processes in allergic airway disease. In this study the bronchoconstrictor effect of inhaled LTD4, and radiolabelled neutrophil accumulation in response to inhalation of LTB4, have been examined in the horse. In separate studies, solutions of LTD4 and LTB4 were administered to the airways of normal animals by nebulisation. LTD4, but not LTB4, caused a dose-dependent increase in pleural pressure which was maximal at three to four minutes and had returned to baseline by 15 to 20 minutes. On a molar basis LTD4 was 305 to 970 tim...
Pulmonary eosinophilia associated with increased airway responsiveness in young racing horses. Horses are known to acquire small airway disease (SAD), an allergen-induced naturally occurring syndrome of reversible obstructive lung disease accompanied by airway hyperresponsiveness and increased inflammatory cell numbers on bronchoalveolar lavage (BAL). This disorder has received scant attention in young racehorses. The purpose of the present report was to examine the effect of BAL eosinophilia in young racehorses on clinical examination, BAL, hematology, airway responsiveness, and on pulmonary function at rest and after a standardized exercise challenge. Five (3 males, 2 females; age 2.6...
Evaluation of an in vitro degranulation challenge procedure for equine pulmonary mast cells. Pulmonary mast cells (PMC) are important components of the inflammatory process in equine allergic lung diseases such as heaves. Very little, however, is known of the degranulation kinetics of these cells and thus, their pathophysiologic role remains largely speculative. The purpose of this study was to develop a repeatable protocol for in vitro equine PMC degranulation. Five mature horses (sex: 2 M, 3 F; age: 8.8 +/- 6.5 y), historically free of pulmonary disease and normal on clinical respiratory examination, arterial blood gas analysis, pulmonary mechanics testing and histamine inhalation c...
Differential superoxide anion generation by equine eosinophils and neutrophils. Equine eosinophils and neutrophils are believed to play an important part in the protection of horses against parasitic and bacterial invasion. Eosinophils may also play a key role in the pathogenesis of equine inflammatory conditions such as the allergic skin disease, insect hypersensitivity. The factors which stimulate the respiratory burst of equine eosinophils and neutrophils are poorly understood. The first aim of the present study was to determine the effects of the phorbol ester, phorbol myristate acetate (PMA), which is believed to activate intracellular protein kinase C, and opsonised...
Airborne dust and aeroallergen concentrations in different sources of feed and bedding for horses. Standardized methods were used to make quantitative and qualitative assessments of respirable dust and aeroallergens in feed and bedding for horses. Concentrations of airborne dust were measured by using a Rion particle counter, and levels of major aeroallergens implicated in chronic obstructive pulmonary disease were measured by using an Andersen sampler. Laboratory conditions allowed comparison of the different sources of forage, supplements, and bedding without external influences such as ventilation, external temperature and horse activity affecting the result. Grass silages of approximate...
Small airway disease as a vanguard for chronic obstructive pulmonary disease. Equine allergic small airway disease is a highly prevalent respiratory condition among the stabled horse population. With the assistance of new diagnostic tools such as bronchoalveolar lavage, the condition can be recognized in young performing horses. The pathophysiological and clinical features resemble an earlier stage of chronic obstructive pulmonary disease as determined by the appearance of specific inflammatory cells. Although environmental management is paramount in controlling the disease, proper selective therapeutic regimens are as important to reduce the concurrent inflammation and...
Influence of antigen challenge on platelet responsiveness in horses with chronic obstructive pulmonary disease. A role for platelets in allergic airways disease has been postulated and changes in the responsiveness of circulating platelets have been demonstrated following antigen challenge of asthmatic human subjects. In this study agonist-induced aggregation of equine platelets in vitro has been compared before and after exposure of horses to a controlled hay and stray challenge. Prior to challenge the response of platelets, from horses with chronic obstructive pulmonary disease (COPD) and normal animals, to adenosine diphosphate (ADP) and platelet activating factor (PAF) did not differ. Five hours aft...
Agonist-induced adherence of equine eosinophils to fibronectin. Eosinophils are believed to play an important part in the pathogenesis of equine diseases such as helminth infestation and the allergic skin disease, sweet itch. It has been shown that adherence of human eosinophils to the connective tissue matrix protein fibronectin enhances cell activation and survival time. If adherence causes similar changes in the properties of equine eosinophils, cell-induced tissue damage at a site of parasitic infestation or allergic response would be exacerbated. However, investigation of this hypothesis requires identification of mediators that cause equine eosinophi...
Frequency dependence of forced oscillatory respiratory mechanics in horses with heaves. The effect of measurement frequency on respiratory mechanics was investigated in six horses with reversible allergic airway disease. Total respiratory impedance was measured at 1.5, 2.0, 3.0, and 5.0 Hz by using the forced oscillation technique with the horses in remission, after acute antigenic challenge producing clinical heaves, and with heaves but after the administration of 2 mg fenoterol by inhalation. The slopes of the magnitude (magnitude of Zrs) and real part (R) of total respiratory impedance over the frequency range 1.5-3 Hz changed significantly after antigenic challenge and fenote...
cDNA cloning and sequencing reveal the major horse allergen Equ c1 to be a glycoprotein member of the lipocalin superfamily. The gene encoding the major horse allergen, designated Equus caballus allergen 1 (Equ c1), was cloned from total cDNA of sublingual salivary glands by reverse transcription-polymerase chain reaction using synthetic degenerate oligonucleotides deduced from N-terminal and internal peptide sequences of the glycosylated hair dandruff protein. A recombinant form of the protein, with a polyhistidine tail, was expressed in Escherichia coli and purified by immobilized metal affinity chromatography. The recombinant protein is able to induce a passive cutaneous anaphylaxis reaction in rat, and it behave...
Further characterization of IgE-binding antigens in horse dander, with particular emphasis on glycoprotein allergens. IgE-binding components in an extract of horse dander were analyzed, especially with regard to the glycoprotein allergens. After SDS-PAGE under reducing conditions and blotting, several of the glycoprotein IgE-binding components, including two distinct bands of 27 and 31 kDa, were detected. Together with several other bands, they were shown to bind to the lectins Sambucus nigra agglutinin (SNA) and Datura stramonium agglutinin (DSA), indicating terminal sialic acid linked alpha 2 --> 6 to galactose, and galactose linked beta 1 --> 4 to N-acetylglucosamine, respectively. Carbohydrate analy...
Allergens of horse dander: comparison among breeds and individual animals by immunoblotting. Some patients who are allergic to horses have reported that they can tolerate certain breeds, and the presence of breed-specific allergens has been suggested. Breeders and patients with asthma have claimed that Bashkir horses are nonallergenic. We used sodium dodecylsulfate-polyacrylamide gel electrophoresis and immunoblotting to determine IgE-binding profiles of extracts of dander obtained from horses of several breeds. We found considerable inter-breed and within-breed variation but no breed-specific allergens. Danders from all breeds investigated contained the most important allergens, and ...
Cross-antigenicity of horse serum albumin with dog and cat albumins: study of three short peptides with significant inhibitory activity towards specific human IgE and IgG antibodies. Horse serum albumin is present in the near vicinity of the animal, while dog and cat serum albumins are very common allergens present in house dust. Human patients clinically defined as allergic to horse could react with horse serum albumin by means of IgE or IgG antibodies. Studies regarding the specificities of these antibodies by inhibition enzyme-linked immunosorbent assay (ELISA) and depletion experiments have demonstrated that they are directed against dog serum albumin and cross-react not only with horse serum albumin but with other serum albumins from different origins. To investigate ...
Immunotherapy trial for horses in British Columbia with Culicoides (Diptera:Ceratopogonidae) hypersensitivity. Immunotherapy was used to treat horses in British Columbia for Culicoides hypersensitivity. This is a severe, chronic, recurrent allergic disease of horses that results in severe irritation, large lesions, hair loss and secondary infection in the ventral midline, mane, and proximal region of the tail. A crude Culicoides extract was injected subcutaneously, in increasing doses, into 10 horses that were affected severely by the disease. Weekly doses reduced the clinical signs in 9 of the 10 horses in the 1st yr. Eight horses were treated with a maintenance dose during a 2nd yr. After the 2nd yr,...
Actions of PAF receptor antagonists in horses with the allergic skin disease sweet itch. Platelet activating factor (PAF) mimics the effects of Culicoides antigen by inducing oedema and inflammatory cell accumulation in the dermis of horses with the allergic skin disease, sweet itch. PAF could therefore contribute to antigen-induced inflammatory changes in these horses. We now report that intravenous administration of the PAF receptor antagonist WEB 2086 (3 mg kg-1), at a dose that inhibited the vascular and cellular responses to PAF in sweet itch horses, reduced Culicoides antigen-induced oedema at 1 h by 73% and at 8 h by 71% (p < 0.05). Neutrophil accumulation and eosinophil...
Parasitic dermatoses that cause pruritus in horses. Insect hypersensitivity is the most common cause of equine pruritus. It is a seasonal, highly pruritic dermatosis that is caused by the salivary antigens of biting insects. The most common insects are discussed in terms of the area of the horse affected, clinical signs, therapy, and preventative strategies.
Overview of equine pruritus. Pruritus is a common complaint associated with equine dermatoses. Self-mutilation results in alopecia, excoriations, scaling, and crusting; the aesthetic appearance of the horse is often ruined and the horse may be unfit for riding or showing. This article specifically addresses those pruritic dermatoses caused by allergies, including food allergy/intolerance, atopy and contact allergy, as well as by two ectoparasites, stick-tight fleas and rhabditic mange. The clinical signs, diagnostic tests, and treatment recommendations are discussed for each disorder. Insect hypersensitivity and pruritus ...
Entomologic evaluation of insect hypersensitivity in horses. Potential methods of incriminating insects as the cause of insect hypersensitivity are presented. A listing of the biting midges known to attack horses in North America is presented also. An example of how species may be determined to be the cause of the hypersensitivity is given using data from a recent study in Florida. Light trap collections indicated the temporal and geographic distribution of potential contributing species and collections made by vacuuming horses further delineated species by proving they feed on horses and the correct locations on the horses to match lesion distribution....
Platelet activating factor mimics antigen-induced cutaneous inflammatory responses in sweet itch horses. Hypersensitivity responses to biting flies such as Culicoides are believed to be the cause of sweet itch, a seasonal intensely pruritic skin condition of horses. Little is known about the mediators released by antigen in the skin of affected horses. In the present study the cutaneous vascular and cellular responses to intradermally injected platelet activating factor (PAF) have been characterised in sweet itch cases during the active phase of the disease and compared with those of Culicoides antigen extract. Histamine was used as a positive control in vascular permeability studies. Responses w...
Tidal breathing flow-volume loop analysis as a test of pulmonary function in exercising horses. The usefulness of tidal breathing flow-volume loops (TBFVL) to evaluate pulmonary function was investigated in 6 Standardbreds during treadmill exercise. Tidal breathing flow-volume loops are a graphic representation of airflow rate vs tidal volume for each individual breath. These TBFVL were obtained from horses exercising at speeds corresponding to 75 and 100% of maximum heart rate. Measurements were recorded in each horse before and after ovalbumin-induced allergic lung disease. Moderate obstructive lung disease, characterized by a significant increase in pulmonary resistance, was observed ...
An unusual manifestation of nettle rash in three horses. Three horses with an apparent neurological disorder resulting from nettle rash showed signs of ataxia, distress and muscle weakness, and two of them had urticaria. In each case the condition resolved within four hours, with no long term problems or recurrence.
Duration of antigen-induced hyperresponsiveness in horses with allergic respiratory disease and possible links with early airway obstruction. Antigen-induced airway hyperresponsiveness in allergic horses has previously been demonstrated when clinical signs of acute airway obstruction were apparent, as a consequence of exposure of animals to hay and straw for variable periods of time, and repeat measurements of hyperresponsiveness have been made no earlier than 1 week after challenge. In the present study airway responsiveness to methacholine has been measured in normal horses and allergic horses in clinical remission before and 24, 48 and 72 h after a hay and straw challenge of fixed, short, duration (7 h). Correlations between earl...