Before the widespread use of telemetry boluses, methods for diagnosing acidosis in cattle involved extraction of rumen fluid for analysis. One method of collecting rumen fluid, called rumenocentesis, involved injection of a large needle through the cow’s side and directly into the rumen. This technique gained popularity in the late 90’s after it was demonstrated by Garrett et al. (1994) as an alternative to ororuminal collection, a procedure often plagued by salivary contamination. The technique is sometimes also known as rumen puncture or, if you are a vet, rumen tap.

Several studies have been completed in the past to determine the effectiveness and dangers associated with rumenocentesis. Tajik et al. (2011) performed rumenocentesis on 196 dairy cows from 10 different herds. Initially 205 cows were selected, but due to a combination of heavy resistance, blood contamination and an inability to locate the rumen it was only possible to sample 196 cows. Twenty four cows out of the remaining 196 showed signs of cutaneous inflammation at the site of puncture with one cow’s inflammation reaching 5cm in diameter.

Another study, Strabel et al. (2007), closely evaluated the clinical and pathological consequences of rumenocentesis on 11 dairy cows. The cows were observed for 7 days after the procedure, then slaughtered to allow complete anatomical and pathological examination. The resulting clinical signs include: forced inspiration (3 cows), transient episodes of hyperthermia (2 cows), haematoma formation at puncture site (9 cows) as well as one cow being culled through necessity due to severe generalized septic peritonitis spreading from the site of rumenocentesis.

It is obvious that, if performed correctly on a suitable cow then rumenocentesis can provide clear results without too much distress to the cow. Although, with the limitations of only acquiring one reading, hard to avoid inaccuracies due to rumen location and the chance of post-operative infection at the site of puncture, it is far from a perfect test.

As the size and position of a rumen can vary greatly, it is difficult to reach the same location within the rumen of each cow. As shown in Tajik et al. (2011) it is sometimes hard enough even finding the rumen, and, as the pH in the rumen differs depending on location, the comparability of rumenocentesis can always be questioned. Ororuminal probes suffer from a similar problem as insertion requires the probe to go deep enough into the cow as to be sure it’s in the rumen, and insertion this far leaves the probe in an unknown location. eCow’s telemetry bolus is specifically designed to be retained in the reticulum where it remains until death, allowing strong comparisons to be drawn between cows.

Another limitation to the procedure is, as rumenocentesis is technically a surgical procedure, it requires a fully qualified veterinarian. First the animal requires sedation, followed by shaving and cleaning of the area to be punctured. The animal is also usually locked in a stall, often restrained. This results in a very lengthy procedure, especially considering more than one animal will need to be tested to check a herd. Methods involving ororuminal probes are faster to perform but they still only provide one reading, and if multiple readings are required the procedure must still be performed each time. In contrast, insertion of an eCow bolus simply requires a balling gun, a tool widely used for administering supplements to cows and subsequent readings are collected automatically.

Perhaps the most obvious disadvantage of rumenocentesis today is that, similar to ororuminal probes, it does not provide continuous data. In order to truly understand the rumen of a cow it is necessary to observe the pH rise and fall. The daily range, the lowest point and the consistency of the daily profile all contribute to a better understanding of the cow not available with rumenocentesis. Although a useful technique in the past, rumenocentesis no longer fulfils a niche.

GARETT, E. F., NORLUND, K. V. (1994) Rumenocentesis: a technique for the diagnosis of subacute rumen acidosis in dairy herds. Bovine Practitioner 28:104

STRABEL, D., A. EWY, T. KAUFMANN, A. STEINER, M. KIRCHHOFER (2007): Rumenocentesis: a suitable technique for analysis of rumen juice pH in cattle? Schweiz. Arch. Tierheilkd. 149, 301-306.

TAJIK, J., M. G. NADALIAN, A. RAOOFI, G. R. MOHAMMADI, A. R. BAHONAR: AJIK, J., M. G. NADALIAN, A. RAOOFI, G. R (2011): Evaluation of rumenocentesis practicability as a routine diagnostic technique in veterinary practice. Vet. arhiv 81, 557-561.