Sudden Death in R1 Dairy Heifers
June 2024

This autumn I was called out to a heifer grazing property where three R1 heifers had been found dead within the last 48 hours.

They were all in the same mob of approximately 70 dairy heifers. The third one had been found that morning and the owners were keen to get a post mortem examination done. The animal was a well grown cross bred heifer. It was slightly bloated, with no sign of struggling or evidence of scouring. The heifers were on pasture only - quite lush because of the favourable autumn conditions.

The causes of sudden death in this age group on a purely pasture diet are quite limited. We discussed possible poisons e.g. Lead, Cyanide, Nitrate, plant poisons such as Yew, Ragwort and Oleander but the conditions were not right for any of these causes. By eliminating these the most likely cause of death in these heifers was a Clostridial infection.

Their vaccination history was uncertain. They had been vaccinated with 5 in 1 as calves but may not have received a booster vaccination. I examined the carcase for signs of Blackleg. There were no characteristic swollen muscles with gas but there was some blood-stained froth from the nose. On opening the carcase, the intestines appeared v inflamed and contained bloody diarrhoea. The kidneys and liver were also swollen and inflamed.

Most of the changes were confined to the digestive tract. The carcass was putrefying quickly considering the heifer was only found dead that morning. Samples were taken for laboratory testing to try and identify the cause. We then looked at the rest of the heifer mob and they were well grown with no sick looking animals.

It was decided to give them a booster 5 in 1 vaccination due to the uncertainty of their vaccination status. Unfortunately we did not get a definitive diagnosis from the laboratory although we were able to rule out acute Salmonellosis. From the history and post mortem signs we made a provisional diagnosis of Clostridial Enterotoxaemia , which is as nasty as it sounds!

Fortunately, the 5 in 1 vaccine routinely used protects against the strains of Clostridia that cause this disease.

No more deaths have occurred in the mob which is a great relief. This case highlights the importance of fully vaccinating calves and on affected farms considering annual clostridial vaccination of heifers and the herd.