datadog output plugin doesn't send the metric type (optional) therefore the metric type is displayed as 'Other' in datadog and COUNT or RATE queries can't be apply
https://docs.datadoghq.com/api/?lang=bash#metrics

Altough telegraf.Metric holds the Type (see https://github.com/influxdata/telegraf/blob/master/metric.go) , the datadog output plugin (https://github.com/influxdata/telegraf/blob/master/plugins/outputs/datadog/datadog.go) Write function discard it and sends only Metric, Tags, Host and Points

metric := &Metric{
Metric: dname,
Tags: metricTags,
Host: host,
}
metric.Points[0] = dogM