Search

BACKGROUND: Dexamethasone is routinely administered to horses but its effect on the antibody response to a commercial EIV/EHV vaccine is unclear. HYPOTHESIS: Horses receiving dexamethasone will have lower postvaccination antibody levels against EIV and EHV-1 than vaccinated controls. ANIMALS: Fifty-five healthy adult research horses. METHODS: Randomized cohort study. Control (no vaccine, group 1), vaccination only (EIV/EHV-1/EHV-4, Prestige 2, Merck Animal Health, group 2), vaccination and concurrent single intravenous dose of dexamethasone (approximately .05 mg/kg, group 3), vaccination and 3 intravenous doses of dexamethasone at 24 hours intervals (group 4). Serum SAA levels were measured on day 1 and day 3. Antibody levels against EIV (hemagglutination inhibition assay, Kentucky 2014 antigen) and EHV-1 (multiplex ELISA targeting total IgG and IgG 4/7) were measured on day 1 and day 30. RESULTS: Significantly increased mean antibody titers after vaccination were only noted against EIV and only after the vaccination alone (n = 14, prevaccine mean [prvm] 166.9, SD 259.6, 95% CI 16.95-316.8; postvaccine mean [povm] 249.1, SD 257.2, 95% confidence interval [CI] 100.6-397.6, P = .02) and the single dose dexamethasone (n = 14, prvm 93.14, SD 72.2, CI 51.45-134.8; povm 185.1, SD 118, CI 116.7-253.6, P = .01), but not after multiple doses of dexamethasone (n = 14, prvm 194.3, SD 258.3, CI 45.16-343.4; povm 240.0, SD 235.7, CI 103.9-376.1, P > .05). CONCLUSION: The effect of dexamethasone on the postvaccine antibody response varies depending on the dosing frequency and the antigen-specific antibody type.

Summary: An 11‐month‐old Thoroughbred filly was referred to the hospital with signs of severe abdominal pain unresponsive to medical treatment. Upon arrival, the filly had a heart rate of 60 beats/min, pink mucous membranes and continued to show severe colic signs despite sedation. Due to the severity of colic signs, general anaesthesia was induced immediately. Exploratory celiotomy revealed a large colon volvulus of more than 360 degrees and hypoplasia of the caecocolic ligament between the caecum and right dorsal colon. The large colon volvulus was corrected, and the filly recovered uneventfully from general anaesthesia. Post‐operative treatment included intravenous fluids and intravenous lidocaine continuous rate infusion, parenteral nutrition, systemic antibiotics, nonsteroidal anti‐inflammatories, gastroprotectants and restricted feeding. The filly experienced several post‐operative complications associated with severe enterocolitis including pyrexia, leukopenia and diarrhoea but made a full recovery and was discharged to the farm after 16 days of hospitalisation. Long‐term follow‐up was available for 22 months after surgery without further reports of colic and the filly had entered race training. Hypoplasia of the caecocolic ligament in association with colic in horses has rarely been reported in the equine literature. To date, only two further case reports of young horses with large colon volvulus and hypoplasia of the caecocolic ligament have been published. In contrast to the presenting case, several other mesenteric abnormalities were present in these two cases in addition to the hypoplastic caecocolic ligament and both horses were eventually euthanised. The pathogenesis of hypoplasia of the caecocolic ligament remains unclear but may include the disruption of early stages of embryogenesis. An abnormal caecocolic ligament has been suggested to potentially predispose horses to large colon volvulus. The presenting case indicates that as an isolated abnormality, a hypoplastic caecocolic ligament may not result in reduced long‐term survival in horses with large colon volvulus. [ABSTRACT FROM AUTHOR]

Summary: A 17‐year‐old Thoroughbred gelding was presented to the hospital with epistaxis, multiple alopecic skin lesions, firm swelling in the masseter region and acute cellulitis of the right hind distal limb. Epistaxis originated from ulcerative lesions within the nasal passages and nasopharynx. Histopathology results of a skin biopsy revealed necrotising dermatitis. Initial laboratory evaluation included severe leucocytosis with marked hyperproteinaemia and adequate coagulation times. A cryoprecipitate was noted in a refrigerated blood sample in the absence of lipemia. Serum protein electrophoresis yielded inconsistent results depending on sample preparation, suggestive of the presence of cryoglobulins. Evaluation of an uncentrifuged sample revealed a gammopathy, with a peak in the beta 2 globulin fraction. Treatment for vasculitis and dermatitis resulted in little clinical improvement, and the gelding was euthanised. Necropsy revealed multicentric lymphoma with a tropism for perivascular spaces and skeletal muscles. [ABSTRACT FROM AUTHOR]