PHOTO: Shutterstock
Anna O'Brien
February 10, 2020

For farm animals, the barn often becomes the clinic when it comes to vet checks and sick animals. And although your vet arrives with all relevant tools in her truck, diagnostics are still limited on the farm. Here’s a peek into the hands-on world of on-farm veterinary diagnostics.


1. Physical exams

It is sometimes amazing what kind of diagnostics information you can glean by using just your hands and your eyes.

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This is, in fact, the basis for the routine physical exam. Poking and prodding can provide a wealth of information about the health of an animal without the need for fancy bells and whistles. For example, feeling for ribs on an animal with a thick coat provides information about its body condition and weight.

More specifically, just lift up an animal’s lip and look at its gums. They should be moist and pink in color. If the gums are dry and tacky or a different color, such as white or dark red, these changes provide your vet with invaluable information.

Next, press your finger firmly against the gums and then lift up. The gums should go from white back to pink in about two seconds. We call this capillary refill time (CRT). It is a simple diagnostic that helps assess an animal’s blood pressure, blood volume and hydration status.

Another diagnostic test in sheep and goats uses mucous membranes, specifically the lower eye lid. On a small ruminant, the inside of the lower eyelid should be a nice pink, similar to healthy gum color.

If the animal has a heavy infection with a common internal parasite called the barber pole worm, this causes extensive blood loss and resultant anemia. This turns the eyelids pale pink to white.

The color of the eyelids can be given a number based on a system called FAMACHA. The FAMACHA score of a particular animal is a great tool to help determine if the animal requires deworming or further supportive care.

2. Simple tools

A doctor without a stethoscope is like a fish out of water.

Veterinarians use stethoscopes in the same ways as physicians: to assess lung and heart sounds.

In farm animals with digestive systems far more complex than mere humans’, vets also use their stethoscopes to listen to gut sounds. The number of rumen contractions per minute is an important diagnostic in ruminants.

In the four quadrants of a horse’s abdomen, active gut sounds provide important information that helps piece together a picture of the animal’s overall health.

3. Quick samples

When a problem isn’t overtly obvious, blood samples can provide additional information.

Typically, a vet will draw blood and fill a few different tubes. Each tube is for a different test.

One common blood test is called a complete blood count, or CBC. This tells us how many white blood cells (and what types) are in the animal’s blood stream. The information can uncover inflammation and possibly infection. It will also provide the number of red blood cells (important for anemia detection).

Another common blood test is called a chemistry panel. This measures electrolytes and various enzymes in the body that tell us about liver and kidney function.

Fecal samples are another simple yet important on-farm collection for diagnostics. When examined under a microscope, a fecal sample provides objective numbers of parasite eggs. Sometimes samples are further tested for bacterial cultures, in some cases of chronic diarrhea.

Bigger tools

Vets use portable radiograph (x-ray) and ultrasound machines on the farm, too.

Radiographs have come a long way over the past few decades. Most clinics use digital machines and can develop on-farm, high-quality electronic images quickly without developing any film.

Radiography in farm animals is primarily used to evaluate lameness. It is an indispensable on-farm diagnostics tool for horses.

Ultrasound use is limited in large animals, similarly to radiographs, due simply to the size of the animals. While cats and dogs commonly undergo abdominal ultrasounds, farm animals are generally too big. Their abdomens are too full of roughage to provide high-quality ultrasound images.

However, ultrasound is fantastic for reproductive assessments in female farm animals. We can easily see the health, size and activity of the ovaries, uterus and fetus in an ultrasound. Most farm vets have their own portable unit.

The next time your vet is out, take note of the samples she takes and ask her what they’re for. You just might be surprised at all the information a small sample of blood or manure can provide!

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