Milverton-Wellesley Veterinary Services
Many of you have at some point struggled with scouring calves. There are many different causes of calf scours such as E coli, Rotavirus, Coronavirus, Cryptosporidium, Coccidiosis to name a few. There are certain management practices, vaccines and other strategies to help prevent certain specific types of scours if you have been able to identify the causative agent. These specific preventive protocols and strategies should be discussed with your herd veterinarian who can help you to identify the pathogen involved and the appropriate preventative protocol. However, these strategies, while certainly beneficial, are often not perfect and producers will still have to treat scouring calves from time to time.
Fortunately treatment protocols for calf scours are usually similar regardless of the cause, and focus mainly on supportive care. The most important of these, however often overlooked, is fluid therapy. In most cases of calf scours that result in a dead calf, it is not the specific infection that kills the calf, but the profound dehydration and acidosis that results. Therefore, fluids for rehydration on going losses are the keys to successful therapy for calf scours. Oral electrolyte solutions, either given by bottle or esophageal feeder are the easiest, cheapest and most practical way to provide fluid therapy, as most producers are comfortable with tubing calves. Commercially available products such as Calf-Lyte, come in ready to mix packets or larger pails, and provide water, glucose, potassium, and bicarbonate, all of which are important in the treatment of the scouring calf. These products are usually dissolved into 2L of hot (37 C or close to body temp) water and administered two to three times daily or as needed. Remember that a healthy 40 kg (100 lb) calf requires 10% of body weight or 4L of fluids daily simply for maintenance, so the same calf that is scouring needs to be given not only 4 L, but much more to account for dehydration and ongoing losses. This practitioner likes to supplement at least 2 L of oral electrolytes mid day to the regular morning and evening milk feedings of the scouring calf that is otherwise bright and alert with a good appetite and strong suck reflex.
If the calf starts to demonstrate signs of depression, weakness, or inappetance, it is often recommended to stop feeding milk and to bottle or tube feed only electrolyes for a day or so. Although the research is somewhat unclear, some oral electrolyte may interfere with the formation of the normal milk clot or curd in the abomasum of the calf. For this reason, many vets do not recommend combining oral electrolytes with milk or milk replacer, but advocate giving it as a separate feeding spread at least a few hours from milk feedings. Basically, if a scouring calf will drink milk, feed it milk. Most experts now recommend continuing to offer milk or milk replacer to the scouring calf as every little bit of intake helps. However, one should never tube feed milk or milk replacer to the scouring calf.
Additionally, oral electrolytes can be supplemented with 1 L of an electrolyte solution such as lactated ringers (Lact R) given under the skin. As the calf progressively gets more dehydrated and acidotic, the signs of depression and weakness worsen. The calf may have a very weak or no suck reflex, and may be unable to get up and remain in sternal or lateral recumbency. Complete loss of the suck reflex is thought to indicate loss of GI function and therefore unlikely that oral fluids can be absorbed. Although subQ fluids may still be attempted at this point, the calf is often very dehydrated (8-10%) and it becomes unfeasible to give 4 L of fluids for maintenance plus an additional 4 or more liters to rehydrate and support ongoing losses, all under the skin. Therefore, intravenous fluid therapy becomes the only option for the recumbent and markedly dehydrated calf. These IV fluids are usually delivered over a 1-2 day period until the calf is much stronger and regains its suck reflex and appetite and can be given oral fluids or milk again.
In addition to fluid therapy, there are several other adjunctive and supportive treatments for the scouring calf. Kaopectate or Pepto-Bismol is usually recommended to help coat and protect the gut lining, while helping to absorb and bind excess fluid and endotoxins. A new product that the clinic has just started carrying is Charcoal-Kaolin Oral Paste which is a combination of kaolin and activated charcoal. Non-steroidal antinflammatories such as Banamine or Flunazine are also often recommended for the scouring calf. This helps to reduce fever, control pain and discomfort, improve appetite, and treat endotoxemia which is especially important for E coli scours (similar to acute watery or toxic mastitis in adult cows).
Finally, antibiotics are also sometimes recommended for the treatment of calf scours. Scour boluses have been around for many years as a popular treatment. There are many commercially available scour boluses to choose from, however not all are created equal. Neomycin and sulfa are the antibiotics common to most scour boluses. The products currently stocked in the clinic are CalfSpan Boluses and NeoSulfaLyte. Calf Span Boluses have both a short acting and a sustained release sulfa antibiotic in the single bolus, maintaining effective levels for up to 4 days. This allows the convenience of a single treatment. Comparatively, Neo-SulfaLyte boluses contain the base neomycin and sulfa antibiotic but not in a sustained released form. Therefore they are labelled as a twice daily treatment. These boluses also contain a combination of electrolytes. Whatever the formulation of the scour bolus being used, the timing and effectiveness of their use will depend on the severity of the clinical signs. Similar to the above discussion with oral fluids, a very weak or loss of a suck reflex indicates GI immotility and lack of absorption meaning boluses can no longer be used. Injectable sulfa antibiotics such as Trimidox are a much more appropriate treatment at that point. It is also important to note, however, that antibiotics will not be effective against many of the causes of scours, such as rota and coronavirus, or cryptosporidium. Antibiotics are likely only to be effective against bacterial causes of scours such as E coli, however they may play a role in helping to prevent any other secondary bacterial infections in the weakened and immunosuppressed calf.
Having said that, there is increasing evidence to suggest that calves treated with antibiotics at a young age have significant alterations to their gut flora that has impact on growth rates and performance well beyond weaning. In fact, many experts are now recommending that calves with simple scours should be treated with fluids and supportive care only. Antibiotics should be reserved only for those calves with fever and profound depression, or bloody scours.