Background: Neonatal foals are born essentially agammaglobulinemic and therefore must ingest colostrum or receive immunoglobulins to maintain health. Failure of passive transfer treatment involves administration of equine colostrum, plasma or commercial powdered colostrum (CPC). Anecdotal reports suggest a risk of anaphylaxis associated with plasma transfusion in neonates that received CPC prior to gut closure. Bovine serum albumin (BSA) in CPC may serve as a target for BSA-specific immunoglobulin E (IgE) in donor equine plasma. Objectives: To determine presence of BSA-specific IgE in samples collected post-routine vaccination in healthy horses, horses experiencing adverse vaccine reactions and commercial equine plasma. Study Design: Prospective Observational Methods: Serum was collected from 65 healthy horses at day 0, 14, 28, 90, 180, 270 and 365 post-vaccination, 26 horses after vaccine reaction at day 1, 180 or 270 post-vaccination, 4 horses not vaccinated and 10 horses from a commercial plasma donor herd. BSA-specific IgE was determined using enzyme-linked immunosorbent assay (ELISA). Results: BSA-specific IgE was not detected in non-vaccinated horses and was identified in all vaccinated horses. Younger horses demonstrated higher fold changes in post-vaccination BSA-specific IgE expression compared to older horses. No significant difference in BSA-specific IgE levels between commercial plasma donors and healthy horses was identified. No significant difference in post-vaccination anti-BSA IgE levels between reactor and healthy horses at day 180 and 270 post-vaccination were identified. Main Limitations: Small number of reactor horses at day 180 and 270 post-vaccination with most samples being collected 24 hours. There were no healthy horse samples for 24 hours post-vaccination; therefore, it was not possible to compare the two groups at this timepoint. Conclusions: Horses may express BSA specific IgE following vaccination. There may be risk of hypersensitivity type reaction when veterinarians administer commercial plasma to neonatal foals that have consumed CPC prior to gut closure.

Summary A 3‐year‐old Gypsy Vanner stallion was presented for evaluation of intermittent recumbency, muscle fasciculations, weakness, low head carriage, shifting of weight between the hindlimbs and an elevated tail head. History, physical examination and serum alpha tocopherol concentrations were suggestive of vitamin E deficiency and equine motor neuron disease (EMND). Sacrocaudalis dorsalis medialis muscle biopsy identified myositis secondary to sarcocystosis. Treatment with alpha tocopherol, ponazuril and sulfadiazine/pyrimethamine resulted in significant improvement in muscle weakness and body condition with resolution of sarcocystosis and inflammation on repeat muscle biopsy. This case illustrates the importance of muscle biopsy in horses with neuromuscular disease as concurrent diseases may be present that require specific treatment for a positive outcome.

A 15-year-old Thoroughbred mare presented to a referral equine veterinary hospital for reoccurring episodes of bilateral blepharitis. The patient was originally examined for a swollen left eye 3 months prior, and the referring veterinarian found no abnormalities. The swelling would resolve only to return after finishing repeated courses of topical antibiotics and dexamethasone with oral flunixin meglumine.On initial presentation, the patient was bright and alert, slightly febrile (101.6°F), tachycardic (heart rate of 50 bpm), and tachypneic (respiratory rate of 20 bpm). The horse was in excellent body condition and appeared well-hydrated. An ophthalmic examination revealed mild bilateral blepharitis, with the upper palpebrae more affected. A grade 5/6 holosystolic heart murmur was identified with normal lung auscultation. No ataxia or lameness was noted.Although not found on the initial presentation, occasional mild distal hindlimb edema was later identified on recheck examinations.Serial complete blood count (CBC, ProCyte Dx; IDEXX, Westbrook, ME, USA), biochemistry profiles (Catalyst One; IDEXX), and electrolyte profiles (iSTAT; Zoetis, Parsippany, NJ, USA) were performed during the patient's stay in the hospital. Results are presented in Table 1. The original CBC demonstrated a mild normocytic normochromic anemia (24%, reference interval 30%-47%), mild lymphopenia (1.14 K/μL; reference interval 1.50-5.10 K/μL), and mild monocytopenia (0.13 K/μL; reference interval 0.20-0.60 K/ μL). Three days later, the patient developed a mild leukopenia (4.71 K/μL; reference interval 4.90-11.10 K/μL). A blood smear evaluation on the second CBC identified marked rouleaux. The serum

SummaryBackgroundNeonatal foals are born essentially agammaglobulinaemic and therefore must ingest colostrum or receive immunoglobulins to maintain health. Failure of passive transfer treatment involves administration of equine colostrum, plasma or commercial powdered colostrum (CPC). Anecdotal reports suggest the risk of anaphylaxis associated with plasma transfusion in neonates receiving CPC prior to gut closure. Bovine serum albumin (BSA) in CPC may serve as a target for BSA‐specific immunoglobulin E (IgE) in donor equine plasma.ObjectivesTo determine the presence of BSA‐specific IgE in samples of commercial equine plasma, samples were collected following routine vaccination in healthy horses and horses experiencing adverse vaccine reactions.Study designProspective observational.MethodsSerum was collected from: 65 healthy horses at days 0, 14, 28, 90, 180, 270 and 365 post‐vaccination; 26 horses after vaccine reaction at days 1, 180 or 270 post‐vaccination; 4 horses not vaccinated; and 9 horses from a commercial plasma donor herd. BSA‐specific IgE was determined using enzyme‐linked immunosorbent assay.ResultsBovine serum albumin‐specific IgE was not detected in non‐vaccinated horses and was identified in all vaccinated horses. Younger horses demonstrated a trend for higher fold changes in post‐vaccination BSA‐specific IgE expression compared to older horses. No significant difference in BSA‐specific IgE levels between commercial plasma donors and healthy horses was identified. No significant difference in post‐vaccination BSA‐specific IgE levels between the reactor and healthy horses at days 180 and 270 post‐vaccination were identified.Main limitationsSmall number of reactor horses at day 180 and 270 post‐vaccination with most samples being collected 24 h. There were no healthy horse samples for 24 h post‐vaccination; therefore, it was not possible to compare the groups at this timepoint.ConclusionsHorses may express BSA‐specific IgE following vaccination. There may be a risk of hypersensitivity type reaction when veterinarians administer commercial plasma to neonatal foals consuming CPC prior to gut closure.