Focus - January 2019
Calf health: the good, the bad and the ugly
Case 1: Scouring Calves
Background
Called out to a 100-cow, spring calving dairy herd in the middle of a busy February. This was a firefighting-type situation as two calves had died overnight and five more were destined for a similar outcome.
The good
The bad
The ugly
Plan of action
Vet Adviser's Plan
Results of investigations
Numerous diagnostic tests were performed, starting with a simple farm-side Snap test, which indicated cryptosporidium was the causative agent. On post-mortem and further tests at the regional vet lab, again cryptosporidium was found. To examine failure of passive transfer (FPT) in these calves, the ZST returned results of 80% FPT with readings between 13-19 units, implying that there was certainly room for improvement in colostrum management. ZST is not classed as the most specific test available but does give good indication of IgG levels in calves. Simple serum IgG tests could have been performed, also using a refractometer in practice. I am certainly guilty of not performing these often enough in practice. It involves taking a serum sample, spinning down or letting it rest, and placing a drop on a refractometer. If using a Brix refractometer, a value of over 8% is optimum or on conventional refractometer a reading greater than 5.5g/dL is optimum. In a Moorpark-based study in 2015, Hogan et al wrote that when compared to other tests available for FPT serum total protein was less specific and sensitive than other tests examined but is still very useful for in-house tests. Of course, there is major scope for farmers to use refractometers to measure colostrum before administration and storage with an optimal value of >22% Brix value. The latest data, from a 2018 Irish study by Todd et al, found a worrying figure of 54% of dairy calves having FPT. As vets, we need to encourage the use of these farm-side tests more.
But!
The elephant in the room in this case was compliance! We should never automatically presume that a product being used on farm is being used correctly. The halofuginone had only been used for four to five days instead of the recommended seven, and had only been started at three to four days of
age instead of after the first feed.
Treatment plan |
Case 2: Sudden Death in calves
Background
This was particularly interesting in terms of unusual disease outbreak that was low down on my differential list due to the farmer’s preventive measures. I was called to a large, 400-cow milking herd towards the end of April.
The good
The bad
The ugly
Treatment plan |
Plan of action
Results of investigations
The result of the post-mortem confirmed a diagnosis of salmonellosis due to Salmonella Dublin. Signs of pneumonia were found cranioventrally distributed involving abscessation of approximately 30% of the lungs. A large abscess was found in the urachal remnant cranial to the bladder and small white foci were found in the kidney, otherwise referred to as ‘spotted kidney’. S. Dublin was positively cultured from one of the lung abscesses present. On further enquiry from vets at the regional veterinary laboratory in Cork, Salmonella can present with a wide range of pathologies and there is not one finding that is diagnostic, culture is always necessary.
Case summary
Lessons to be learned from this case are that, despite vaccination, diseases can occur if the infection pressure is high enough. Typically, in Ireland, Salmonella vaccine is primarily used as an anti-abortion vaccine and calves are not generally immune, unless boosters are given closer to calving. The complex presentation of salmonellosis can be confusing to both famers and vets, with very general clinical signs and, unfortunately, not always the textbook blood red scour. After visiting Salmonella-positive farms in Denmark this year, they take their Salmonella prevention very seriously and their biosecurity is second to none. Separate wellingtons for vets/visitors on the farm is commonplace and disinfectant spraying of all personal protective equipment before arrival and departure of the farm is obligatory.
Case 3: Bloated Calves
Background
This case was not isolated to one farm outbreak or animal but was a reoccurring issue that I encountered throughout the spring of 2018. It can be frustrating to treat bloat as the etiology is a little complicated and there are no straightforward answers. The main principle of a bloat outbreak involves the excessive fermentation process of high-energy milk or milk replacer in the abomasum resulting in overproduction of gas. The most common bacterial involvement would be Clostridium perfringens A. due to poor storage of colostrum and subsequent bacterial overgrowth.
General bloat prevention recommendations:
Treatment
Curve balls
Conclusion
For younger vets, the ‘text book’ case presentations that we study in vet school do not always translate to real-life situations and this is where help from more experienced vets and vet advisers is vital. Farm animal medicine keeps me on my toes constantly; even when you think you have sussed out a case, a curve ball can be thrown at you at the last minute. In general, calf health is the first building block to a successful farming enterprise and, as vets, we can share our knowledge to help farmers prevent disease and control outbreaks in their calves. As a recent graduate in practice over the past five years, I have realised that every single calf scour, pneumonia outbreak and miscellaneous sick-calf call has contributed to my overall knowledge base. The old saying ‘every day is a school day’ certainly rings true for anyone involved in the exciting world of veterinary medicine.
Acknowledgement
Hazell Mullins BVM BVS, presented at the 2018 CAVI Conference on the topic of calf health, ‘the good, the bad and the ugly’ of some of the real-life cases she has encountered.
Hazell would like to thank CAVI organisers for the opportunity to share her professional experiences, enabling her to reach out to younger vets who were in attendance and to help them overcome the pressures of calf health challenges in those first few years in practice.