Equine fecal microbiota response to short term antibiotic administration.

Though generally safe, research continues to demonstrate negative side effects of antibiotic administration on the gastrointestinal (GIT) microbiota across species. In horses, antibiotic associated diarrhea (AAD) is a life-threatening condition linked to the GIT microbiota. This study tested the hypothesis that short term antibiotic administration to healthy horses would negatively impact the fecal microbiota as measured by their ability to digest nutrients and through fecal shedding of disease-associated-bacteria. Twenty-four horses were assigned to one of four treatment groups: control (CO); potassium penicillin/gentamicin sulfate (KPG); ceftiofur crystalline free acid (EX); trimethoprim/sulfamethoxazole (SMZ); and treated for 4 days. Fecal samples were collected before treatment began (S0), the day after treatment conclusion (S5), and at 10, 14, 21, and 28 days after initiating treatment. Horses had highly individualized responses to antibiotic administration. All horses receiving antibiotics experienced significantly softer stool compared to controls. Lactobacillus spp. were dramatically reduced in all antibiotic treated S5 samples. Horses receiving antibiotics were significantly more likely to test positive for C. difficile or C. perfringens on fecal qPCR. In conclusion, response to antibiotic administration displays high inter-individual variability, but shows changes to the functions of fecal microbiota that may depend on the antibiotic used.

Detection of cold-adapted vaccine-strain influenza virus using two commercial assays.

Because of the contagious nature of influenza virus it is necessary to identify infected individuals after the virus is introduced into a population. The aim of this study was to characterise influenza virus detection with commercially available assays after intranasal vaccinating horses with cold-adapted influenza virus. Seven horses were vaccinated and placed with 3 unvaccinated horses. Nasal secretion samples were evaluated using 2 antigen detection assays. All 10 horses were positive in the Flu OIA assay during the study period, but only one horse was positive on one sample using the Directigen Flu A assay. Horses were most likely to be positive during the first 3 days following vaccination, and several horses were intermittently positive for several days after this. Obtaining positive test results from nonvaccinated, incontact horses suggests they became infected with vaccine-strain virus that was shed by vaccinated horses. These results are important for the correct interpretation of influenza antigen detection tests in situations when this modified-live intranasal vaccine has been used.

Evaluation of a modification of the Hudson demand valve in ventilated and spontaneously breathing horses.

Hypoxaemia commonly develops during general anaesthesia and in the recovery period in horses. The Hudson demand valve has been used to increase arterial PO2, but it has been found to increase airway resistance considerably when used during spontaneous ventilation. This paper evaluates a modification of the valve designed to reduce this resistance. The effects of the valve and its modification on arterial oxygen (PaO2), and carbon dioxide (PaCO2) tensions were evaluated in four ponies anaesthetised by a total intravenous technique. The valve increased PaO2 from 8.3 +/- 1.1 to 32.7 +/- 7.6 kPa during spontaneous ventilation and to 44.2 +/- 7.4 kPa during intermittent positive pressure ventilation. With the modification, the PaCO2 was increased to 9.0 +/- 2.5 kPa during spontaneous ventilation PaO2 was unchanged by the valve (7.2 +/- 0.4 kPa to 7.1 +/- 0.7 kPa) but it was reduced to 6.4 +/- 0.9 kPa with the modification. The valve was also evaluated in 20 clinical cases during their recovery from halothane anaesthesia. It increased PaO2 from 7.4 +/- 2.1 kPa to 17 +/- 18.3 kPa during spontaneous ventilation and from 8.0 +/- 1.8 kPa to 23.4 +/- 22.2 kPa during positive pressure ventilation. With the modification, PaO2 was increased from 7.8 +/- 1.4 kPa to 10.4 +/- 3.8 kPa during spontaneous ventilation and from 7.6 +/- 1.5 kPa to 14.8 +/- 8.4 kPa during positive pressure ventilation. During spontaneous ventilation PaCO2 was increased from 5.9 +/- 0.4 kPa to 6.2 +/- 0.6 kPa with the unmodified valve and from 6.3 +/- 0.5 kPa to 6.6 +/- 0.5 kPa with the modification.(ABSTRACT TRUNCATED AT 250 WORDS)