8.5 Large Animal Procedures
Herd Health Principles
Production animals like cows, sheep, goats, and pigs are often managed as a group rather than individually, as they live in herds and there are generally a large number of them per facility. Management practices will therefore affect multiple animals. Likewise, from a health standpoint, it has to be kept in mind that not one, but multiple animals will be exposed to a disease. As a result, the prevention of disease on farms needs to be targeted towards groups of animals and the entire herd, rather than individual animals. Disease prevention is crucial for the economic survival of the farm and to ensure animal welfare (Root Kustritz, 2022a).
Management practices play a crucial role in disease prevention on farms, and the environment is also hugely important. Management practices often aim to decrease risk of infection by managing hygiene, biosecurity, and nutrition. This can reduce both exposure to a disease and the probability that the animals are negatively affected by it (Root Kustritz, 2022a).
Vaccination
The purposes and benefits of vaccinating are outlined in Chapter 6. Each species has its own recommended vaccine protocols that vary depending on geographic region and risk of exposure. In Canada, many livestock vaccines are administered by farmers. Even when some vaccines can be purchased over the counter by owners or farmers, it is always recommended that they develop a vaccination plan with their veterinarian in order to best meet their animals’ needs (Root Kustritz, 2022a).
When choosing a vaccine protocol, veterinarians consider the following:
- Environment
- Risk of disease exposure
- Risk tolerance of the farmer or owner
- Severity of disease
- Timing of vaccines
(Root Kustritz, 2022a)
Vaccine Notes
Different species have different recommended locations and routes of vaccine administration, so it is always important to double check if the vaccine should be administered under the skin (SQ), in the muscle (IM), or even up the nose (IN).
Parasite Control
Apart from bacteria and viruses, we also have to worry about parasite infestations on farms. Both internal (residing within the body) and external (residing on the surface of the body) parasites can negatively affect health and lead to disease. In large animals, there is concern about parasites’ resistance to available deworming medications, and great attention is paid to minimizing development of resistant parasites. Resistant parasites are those which are not affected by the drugs that we would normally use to kill them. Gastrointestinal parasites are the class most commonly addressed (Root Kustritz, 2022b).
Testing for Parasites
Tests are used to evaluate for presence of gastrointestinal parasites. In farm animals, we commonly use the following:
- Fecal egg count: Feces are mixed with a special solution and placed on a slide to visualize presence of parasite eggs under the microscope. The number of eggs in a certain area are counted and identified.
- This test can help determine if an animal has parasites or not and how many there are, which helps determine whether or not deworming is needed.
(Root Kustritz, 2022b)
Similar to vaccines, each species will have a unique recommended deworming schedule. Deworming refers to removing internal parasites from an animal. Whether we treat or test for parasite burden depends on the situation.
Common Management Procedures
In large animals, generally only the males undergo gonadectomies. Females tend to only get ovariohysterectomies if medically required. Castration is the term used in large animals for removing the testicles. In North America, male pigs and cows are also castrated for improved meat production and taste. Horses are not as commonly used for meat in North America as they are for sport, work, or companionship, so the reason behind castration (or “gelding”) is different. Generally, geldings are considered to be calmer and easier to work with than stallions, and it makes housing easier since they cannot reproduce (Root Kustritz, 2022c).
Cattle:
- Dehorning: Some cows have their horns surgically removed
- Ear tag application: Tag put through the ear of the cow
- Can be used for identification
- Vaccinating
- Deworming
- Castration
Figure 8.21 Beef cow with ear tags
Horses:
- Dental floats: Filing down a horse’s teeth is important, because they grow constantly and can become painful if not properly cared for
- Vaccination
- Deworming
- Castration
- Hoof trimming: Similar to human nails, horses’ hooves are constantly growing. In order to maintain proper hoof balance and alleviate pain, farriers regularly trim hooves.
Figure 8.22 One testicle following castration of a colt
Pigs:
- Vaccinating
- Deworming
- Castration
- Tail docking: Tails are removed when piglets are young to prevent others from biting it, which can lead to disease
Surgery
You are probably familiar with the image of dogs and cats being anaesthetized on a surgical table and maintaining their state of unconsciousness via gas, similarly to humans. This is not as common in large animals, as it takes a lot of resources to anaesthetize a 1000lb animal and put it on a table. While this does happen, it is more common in specialty and referral centres.
Forms of Surgery in the Field
- Standing: The animal remains standing. Light sedation can be used in addition to local anaesthesia to reduce sensation at the surgical area. This is common in cows and can also be done with horses, depending on the procedure and the temperament of the horse – always consider safety! (Malone, n.d.).
- Recumbent field surgery: Animals are completely anaesthetized and are laying down. When in the field, we generally do not intubate animals, as there is no oxygen source. Therefore, we maintain anaesthesia with IV injections as needed. This is common in horses. Small ruminant procedures are often performed with the patient recumbent – but since they are smaller, we can sometimes just use sedation here instead of general anaesthesia (Malone, n.d.).
Restraint
Restraint is very important in all species when practising veterinary medicine. Not only does it keep our vet team safe, but it also keeps our patients safe. Just as it could be disastrous for an old dog to jump off of an exam table and hurt itself on landing, letting a horse loose while working on it could lead to any number of disasters. It is generally helpful for owners or farmers to work with their animals before the vet team makes it to the farm, and gets them used to handling. This is called desensitization. Horses, dairy cattle, and small flocks of sheep and herds of goats are generally more used to handling, but beef cattle are often left to roam in pastures for months at a time and rarely interact with humans. This greatly affects our handling when visiting.
We use restraint during sample collection, administration of medication and vaccines, and almost any procedure. Understanding species’ behaviours and listening to owners can help facilitate restraint and make it a better experience for both restrainer and animal. Many owners are aware of their animals’ preferences, which can greatly help guide which restraint would work best for them. There are multiple techniques, and sometimes it takes some trial and error to determine which works best for a specific patient.
In all species, we can use chemical restraint, which involves using drugs to sedate an animal so they are easier to work with (Root Kustritz, 2022d).
The following boxes will describe some species-specific handling and restraint strategies and equipment we use in veterinary medicine.
Horses
- Horses communicate mainly through body language and tension, and tend to be able to read human body language as well. It is important to remain calm and relaxed when working with horses, because if their handlers are nervous, the horses become nervous too. However, no matter how sweet a horse may seem, every horse will react to something if it is scary or painful enough. Therefore, being aware of behaviour changes and the environment is extremely important (Root Kustritz, 2022d).
- In North America, horses are often handled from the left side, so it is best to start there (Root Kustritz, 2022d)
- Procedures should never be done on a horse without someone experienced on the other end of a lead rope!
- Halter: Equipment placed on the head of the horse for restraint. Straps wrap around the nose and behind the ears. This is often either nylon or rope (Finley, 2012).
- Lead rope: Length of rope that attaches to the halter, often used in restraint of a horse
- Stocks: Restraint equipment that prevents a horse from moving forwards or backwards
- Safety tip: Horses tend to kick straight backwards. Leave lots of space when walking behind them! (Root Kustritz, 2022d)
- Behaviour tip: Horses communicate a lot with their ears. If they are pinned backwards, that is a sign they are upset (Root Kustritz, 2022d).
Figure 8.24 Horse wearing a nylon halter
Horse Body Language
JSHorsemanship. (2021, March 19). Horse behavior and body language [Video]. YouTube. https://youtu.be/vliq-8oXQ4A
Cows:
- Some cows can be restrained with a rope halter, but oftentimes cows are restrained in chutes that prevent them from leaving, and hold their head (Finley, 2012)
- A tail jack can also be used when restraining cows, which includes lifting the tail upwards from the base (Finley, 2012)
- Safety tip: Cows tend to kick forwards or sideways, which is different than horses. We also have to be aware of their horns! (Finley, 2012)
Figure 8.28 Cow in chute
Sheep:
- Sheep can be mostly immobilized by lifting their head from under their chin. They are also often “flipped” onto their haunches into a sitting position and tend to stay relatively still when positioned that way (Finley, 2012)
Exercises
References
Finley, M. R. (2012). Restraint techniques for large animals. U.S. Department of Energy. https://www.osti.gov/servlets/purl/1649748
Root Kustritz, M. (2022a). 4. Vaccines and vaccinations: Production animals. In Veterinary preventive medicine. University of Minnesota. https://pressbooks.umn.edu/vetprevmed/chapter/chapter-4-vaccines-and-vaccinations-production/
Root Kustritz, M. (2022b). 5. Parasite control. In Veterinary preventive medicine. University of Minnesota. https://pressbooks.umn.edu/vetprevmed/chapter/chapter-5-parasite-control/
Root Kustritz, M. (2022c). 6. Reproduction control. In Veterinary preventive medicine. University of Minnesota. https://pressbooks.umn.edu/vetprevmed/chapter/chapter-6-repro-control/
Root Kustritz, M. (2022d). 9. Behavior. In Veterinary preventive medicine. University of Minnesota. https://pressbooks.umn.edu/vetprevmed/chapter/chapter-9-behavior/
Malone, E. (n.d.) General approach to surgery and anesthesia in large animals. In Large animal surgery – supplemental notes. University of Minnesota. https://open.lib.umn.edu/largeanimalsurgery/chapter/general-surgery-approach/
Image Credits (images are listed in order of appearance)
Beef cow with ear tags by Matéa David-Steel. Used with permission.
Cattle horn by Matéa David-Steel. Used with permission.
Horse testicle by Matéa David-Steel. Used with permission.
Farrier at work J2 by Jamain, CC BY-SA 3.0.
Horse wearing halter by Unknown, CC0.
Horse in stocks by Penny Radostits. Used with permission.
Horse from above by Leo von Salisch, CC BY-SA 4.0.
Squeeze chute by Montanabw, CC BY 2.0.
Cow in chute (head) by Matéa David-Steel. Used with permission.
Cow from above by Leo von Salisch, CC BY-SA 4.0.
Special operations civil affairs medical sergeants training by K. Kassens, CC0.
Animals used in farming to produce goods (e.g. cows for milk/beef, pigs for pork, chicken for eggs, etc.)
Removal of the testes, generally used when referring to large animals
Term for castration specifically in horses
Professionals who care for hooves (e.g., trimming, balancing); primarily work with horses
The procedure of exposing an animal to a situation slowly in order to make it less stressful in the future
Large piece of equipment that stabilizes a cow, often immobilizing their head
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