Is Bovine Respiratory Disease Painful?

This article was written by Dr. Miriam Martin, Kansas State University College of Veterinary Medicine.
 

On a cold day in October, researchers at Kansas State University College of Veterinary Medicine set out to answer the question, “Is bovine respiratory disease (BRD) painful?”

Using an induced BRD model, the objectives were to (1) assess if bacterial pneumonia is painful, (2) determine if pain biomarkers collected at certain time points in the disease process could predict lung consolidation, and (3) to explore the analgesic effects of transdermally administered flunixin.

Calves with no history of BRD were enrolled into one of three treatment groups:

(1) experimentally induced BRD + transdermal flunixin at 3.3 mg/kg,

(2) experimentally induced BRD + placebo, and

(3) sham induction + placebo.

Calves induced with BRD were inoculated with Mannheimia haemolytica via bronchoalveolar lavage. Outcomes were collected from -48 to 192 hours post-treatment and included serum cortisol; infrared thermography; mechanical nociceptive threshold; substance P; kinematic gait analysis; pain score using a visual analog scale; clinical illness score; computerized lung score; average activity and rumination level; prostaglandin E2 metabolite; serum amyloid A and rectal temperature.

After the 192-hour collection time point, calves were euthanized and assigned a lung consolidation score by a pathologist.

Results showed that a combination of reduced activity levels, decreased force on the right-front limb, and increased visual analog scale pain scores all support that bacterial pneumonia in cattle is painful.

Activity levels were quantified via 3-axis accelerometers mounted on an RFID tag. Force was measured via gait analysis by walking calves across a pressure mat that quantifies changes in stride and weight distribution.

Even the most trained eye assessing cattle behavior has limitations. Through advanced technologies that allow for continuous and objective quantification of behavior and gait, the ability to detect changes early on in the disease process before the animal is showing clinical signs noticeable to the human eye is a very real possibility, giving us the opportunity to prevent pain and suffering.

In the first 72 hours after onset of BRD, right-front stride length, gait velocity, visual analog scale pain score, clinical illness score, average activity level, step count and rectal temperature yielded the best diagnostic accuracy for predicting calves with significant lung lesions (>10% lung consolidation scores) at necropsy compared to those with <10% lung consolidation scores.

Calves that received flunixin transdermal placed more force on their right-front limb indicating that flunixin transdermal may have attenuated some of the pain associated with BRD.

It is noteworthy that in the induced BRD treatment groups, calves’ right apical lung lobes were inoculated. The finding of calves placing less force on their right-front limb when painful may be indicative that gait measurements more specific to the area of disease pathology may yield better results.

Analgesic use to alleviate pain from common husbandry procedures such as castration and dehorning is evolving. However, alleviating pain and suffering via analgesic use should not be limited to husbandry procedures, but its use extended to painful disease states such as BRD.

One factor contributing to the low adoption rate of pain mitigation protocols on cattle operations is the lack of FDA-approved analgesic drugs. Veterinarians are permitted to prescribe analgesic drugs following guidelines allowed under Extra-Label Drug Use (ELDU) by the Animal Medicinal Drug Use Clarification Act (AMDUCA).

Other factors contributing to low adoption of pain-mitigation protocols include a lack of analgesic options that control pain for an extended duration and a lack of formulations that are practical to administer.

Continued pressure to prioritize animal well-being and mitigate pain is driving the need for the approval of more analgesic drugs with an extended duration of action and new drug formulations. Analgesic use in food animals is becoming more common, and as we develop more advanced technologies to predict illness and characterize pain, implementation will become the next hurdle.

Having conversations with producers about their options to prevent pain and suffering is something we can do now. Advances in animal monitoring and diagnostics coupled with implementation of practical analgesic protocols can lead to improved cattle well-being which is a story worth telling.

For access to the scientific publication in the Journal of Animal Science visit: https://academic.oup.com/jas/article/100/2/skab373/6473170

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