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Incorrect. Culture of 3 nasopharyngeal swabs, collected a week apart, is the most common way to diagnose the strangles carrier state, however it only diagnoses 66% of carrier horses. PCR increases the sensitivity to 90%, and using guttural pouch washings increases this further, making culture and PCR of guttural pouch washings the most sensitive test for the strangles carrier state. When taking nasopharyngeal swabs, it is important to sample the back of the pharynx around the opening of the guttural pouch, to get the most reliable sample. This is done using specially designed elongated swabs with enlarged absorbent heads. Shedding of S. equi into the nasopharynx often occurs intermittently, so repeated swabbing is recommended to confirm negative results. Link to WikiVet: Strangles
Incorrect. Whilst PCR is more sensitive than culture, S. equi is only shed into the nasopharynx intermittently, so a single swab is unreliable for the carrier state. The most common way to diagnose the strangles carrier state, is culture of 3 nasopharyngeal swabs collected a week apart, however it only diagnoses 66% of carrier horses. PCR increases the sensitivity to 90%, and using guttural pouch washings increases this further, making culture and PCR of guttural pouch washings the most sensitive test for the strangles carrier state. When taking nasopharyngeal swabs, it is important to sample the back of the pharynx around the opening of the guttural pouch, to get the most reliable sample. This is done using specially designed elongated swabs with enlarged absorbent heads. Link to WikiVet: Strangles
Correct! Culture of 3 nasopharyngeal swabs, collected a week apart, is the most common way to diagnose the strangles carrier state, however it only diagnoses 66% of carrier horses. PCR increases the sensitivity to 90%, and using guttural pouch washes increases this further, making culture and PCR of guttural pouch washings the most sensitive test for the strangles carrier state. Link to WikiVet: Strangles
Incorrect. Blood samples can be used to diagnose an active strangles infection, but the latent carrier state may not be diagnosed in this way. The most common way to diagnose the strangles carrier state, is culture of 3 nasopharyngeal swabs collected a week apart, however it only diagnoses 66% of carrier horses. PCR increases the sensitivity to 90%, and using guttural pouch washings increases this further, making culture and PCR of guttural pouch washings the most sensitive test for the strangles carrier state. When taking nasopharyngeal swabs, it is important to sample the back of the pharynx around the opening of the guttural pouch, to get the most reliable sample. This is done using specially designed elongated swabs with enlarged absorbent heads. Link to WikiVet: Strangles
Incorrect. You are correct in realising that guttural pouch lavage fluid gives greater sensitivity for diagnosis of the strangles carrier state; however, a positive PCR result may detect dead DNA, where viable, infectious organisms are no longer present, so bacteriological culture should always be used to definitively confirm status. The correct answer is culture AND PCR of guttural pouch washings is the best way to diagnose the strangles carrier state. Link to WikiVet: Strangles
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