Evaluating calves for wellness

by Sally Colby

Calf feeders can be among most important personnel on the dairy when it comes to recognizing calf illness. Properly trained employees who learn and pay attention to the habits of healthy calves will be able to identify early signs of illness in young animals, which can save calves’ lives and result in healthier replacements.

Dr. Jessica Pempek, assistant professor and animal welfare specialist, Ohio State University, said the most common problems in young calves are navel infections, diarrhea and respiratory disease. As cooler weather and winter approach, respiratory disease will become a leading cause of illness and death in pre-weaned dairy calves.

Familiarity with normal calf behavior helps those who work with young calves be proactive instead of reactive, and to recognize slight changes before there are obvious clinical signs of disease. Understanding and recognizing “normal” helps identify calves that may need antibiotic treatment or other therapy. Pempek said the goals are to recognize illness, reduce the severity of disease and reduce the number of sick calves.

The best time to observe calves is at feeding time. A healthy calf has bright eyes, has its ears forward and is curious and attentive to its surroundings. Calves should get up and stretch when approached. “Healthy calves will be eager to eat,” said Pempek. “They anticipate their milk meal. Any changes to the amount consumed or drinking speed likely indicates the calf may not be feeling well.”

Calves should get up as feeding time approaches and should react to the presence of the calf feeder. Pempek also advised observing calves one to two hours after milk feeding – calves that seem hungry and eager to eat can appear to be normal. Small changes in respiration aren’t always obvious when calves are up and eager to eat, so it’s best to observe them both during and after milk feeding.

Sick calves may appear to be depressed, may drink less or drink more slowly and, depending on the illness, show increased respiratory effort. “Observe the calf from a distance, prior to entering the pen and disturbing them,” said Pempek. “If you aren’t sure if the calf has increased respiratory rate, compare that calf’s breathing to neighboring calves.” If a calf appears to be depressed, a more thorough exam should include four main indicators: dehydration, rectal temperature, diarrhea and signs of respiratory disease.

Calves that appear ill should be assessed for hydration status. “An easy way to assess dehydration is the skin tent test,” said Pempek. “Pinch a fold of skin on the calf’s neck, rotate it 90 degrees, release the skin and count the number of seconds it takes for the skin to flatten.” The skin of a well-hydrated calf is pliable and will snap back and flatten in two seconds; if it takes longer than two seconds, the calf may be dehydrated. Sunken eyes indicate moderate to severe dehydration, but routine monitoring should help avoid reaching that stage.

Rectal temperature should always be on the list of steps to determine what’s wrong. Increased temperature is usually due to infection or inflammation; fever is the body’s natural response to fighting an infection. Persistent fever can lead to animals going off feed or stunt production. In young calves, a rectal temperature of 103º F or greater is considered a fever.

It’s important to consider ambient temperature when assessing a calf for fever. In hot weather, a healthy calf may have a temperature at or above 103.5º. If you’re unsure whether a calf has a true fever, take the rectal temperature of the suspect calf and compare it to the temperatures of several other nearby calves.

Pempek said a single temperature reading is just a snapshot and isn’t sufficient basis for a treatment decision. A calf suspected of becoming ill should have its temperature monitored over several consecutive days (ideally several times a day). For an accurate reading, be sure to place the thermometer against the anal wall. “If a calf poops mid-reading, take the temperature again,” said Pempek. “This is important because air in the rectum will influence the temperature reading.”

Diarrhea in calves can be caused by bacteria, viruses or protozoa and can result in rapid dehydration. A calf that is slightly dehydrated is missing more than a gallon of fluid, so fluid therapy is critical. Fluid therapy is the most important intervention in treating diarrhea, and must match the calf’s regular needs, including the fluid deficit and ongoing losses due to diarrhea.

Pempek said mixing electrolytes with milk can make diarrhea worse. A good rule of thumb is to feed electrolytes either 30 minutes before or two hours after milk feeding. After a calf is identified as having diarrhea, continue to evaluate, including assessing attitude, hydration status and fever status. Employees should consult the farm’s written veterinary protocol for treatment options.

Respiratory disease is a significant issue in young calves, and caretakers should be trained to recognize early signs of it. In many cases, respiratory illness can be linked to multiple causes and can be a combination of viral and bacterial infections, and they’re sometimes related to management and/or environmental stressors.

“Diagnostic tests can be expensive so calf producers should be trained to be able to consistently assess an animal’s health status,” said Pempek. “A respiratory disease scoring system can be used as a diagnostic tool to identify animals for treatment in a more timely and consistent manner, hence improving animal welfare and ultimately minimizing the use of antibiotics to treat animals that may not be suffering from respiratory disease.”

A scoring system to assess respiratory illness, developed at UC-Davis, assesses six clinical signs with points for discharge from the eyes and nose, ear droop/head tilt, cough, respiration and fever. This scoring system is intended to be quick, so a rectal temperature for every calf is only needed if the total score for visible clinical signs is 4 or higher.

“No eye discharge receives a 0, and eye discharge of any severity is 2,” said Pempek. “For nasal discharge, a score of 4 is assigned for any visible discharge. A healthy calf should have no apparent head tilt or ear droop. Any sign of head tilt or ear droop receives a 5.” A total score of 5 indicates a calf likely has respiratory disease and should receive appropriate therapy according to protocols developed by the farm vet.

“With early disease diagnosis, we have better health and welfare outcomes for calves,” said Pempek. “With better health, there will likely be lower treatment costs and fewer antibiotics used.”

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