Neck Issues in Warmbloods

Hello, Summarians!

Pain, how to recognize it, and how to treat it can be a confusing issue. Here are a couple of articles that look at these issues. Plus a bonus look at challenging seizure cases.

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Cervical Issues in Warm Bloods

Cervical pain, neck stiffness, thoracic limb lameness, and ataxia in horses have been linked to radiological abnormalities in the caudal cervical vertebrae. While some clinical features associated with primary neck lesions in horses have been documented, recent studies call for systematic evaluations by experienced specialists to better understand these conditions. With advancements in imaging techniques like computed tomography and digital radiography, detecting radiological abnormalities in the cervical vertebrae has become easier, yet their clinical relevance can be overinterpreted without considering the horse's clinical signs. 

The study aimed to describe clinical features associated with neck pain, thoracic limb lameness, and general proprioceptive ataxia, hypothesizing that these features would be more frequent in horses with primary neck pathology compared to control horses. The findings confirmed that features like neck stiffness, pain, neurological dysfunction, and thoracic limb lameness were more prevalent in horses with neck pathology. Specific signs such as focal cervical muscle atrophy, patchy sweating, focal hypoesthesia, hyperesthesia, and abnormal grazing posture were unique to affected horses. These assessments, though subjective, revealed repeatable patterns, highlighting the importance of thorough, standardized clinical examinations. 

Localized or generalized neck muscle atrophy is a significant indicator of neck-related problems. Cases showed lower body condition scores than controls, likely due to neurogenic and disuse muscle atrophy, decreased muscle tone from altered neurologic input, movement restrictions, and decreased food intake from neck pain. Pain upon palpation, hypoesthesia, and hyperesthesia were also key findings. The study noted that the brachiocephalicus muscles often showed pain upon manual compression in horses with caudal cervical pain, although this was not systematically compared between cases and controls. 

Clinical features like tactile hyperesthesia of the thoracic limbs, low neck posture, and "neck locking" were observed in horses with primary neck problems. Restricted cervical flexion, tilting of the head and neck, and root signature posture were other indicators of caudal cervical issues. Thoracic limb lameness was more evident during ridden exercise, emphasizing the need for evaluations under these conditions. Additionally, thoracic limb stumbling, hopping type lameness, and irregular pelvic limb rhythm were more common in affected horses. 

The study highlighted the importance of observing transitions between gaits to assess gait abnormalities. Primary pelvic limb lameness and neck-related issues could coexist, with diagnostic anesthesia helping differentiate them. The presence of bilateral delayed release of the patella in neurologic cases indicated decreased muscle tone and strength from upper motor neuron deficits. 

Desensitization of the foot through perineural anesthesia sometimes increased lameness severity if the foot was not the primary pain source. Electromyography (EMG) proved useful in identifying affected spinal cord segments or nerve roots in horses with thoracic limb lameness, supporting the diagnosis of neurological origin. Despite some limitations, the study found that many clinical features were either unique to or more frequent in horses with neck-related problems compared to controls. This systematic observation aids in distinguishing caudal cervical lesions from other gait abnormalities, with EMG providing additional support for neurological dysfunction localization. 

Dyson S, Zheng S, Aleman M. Primary phenotypic features associated with caudal neck pathology in warmblood horses. J Vet Intern Med. 2024; 38(4): 2380-2390. doi:10.1111/jvim.17125 

Bottom line — Useful information especially versus control populations

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Medium Chain Triglycerides and Seizures

Seizures and epilepsy are prevalent neurological conditions in dogs, affecting about 0.6%-0.8% of the population. Epilepsy, characterized by recurrent unprovoked seizures, has poorly understood cellular mechanisms, resulting in treatments that focus on seizure suppression rather than prevention. Chronic antiseizure drug (ASD) administration is common, but about one-third of dogs continue to experience seizures despite polypharmacotherapy. Additionally, dogs with epilepsy often suffer from behavioral and cognitive issues, reducing their quality of life (QoL). 

Nutritional management has been explored as an alternative treatment approach. A cross-sectional study showed that over 60% of dog owners altered their pet's diet following an epilepsy diagnosis, aiming to improve seizure control and reduce ASD-related side effects. Studies in humans, rodents, and dogs have shown varying degrees of antiseizure effects from dietary modifications. A notable 6-month study compared the effects of a medium-chain triacylglyceride (MCT) kibble diet to a placebo in 21 ASD-treated dogs with idiopathic epilepsy (IE), revealing significant improvements in seizure control and behavioral comorbidities. 

The current study aimed to assess the antiseizure efficacy and tolerability of an MCT oil supplement in dogs with IE. In a 6-month randomized, placebo-controlled trial with 28 dogs, MCT oil supplementation significantly reduced seizure frequency and was well-tolerated, demonstrating potential as a dietary management option. While results showed an overall modest reduction in seizure frequency, individual responses varied, with some dogs achieving significant seizure reduction or freedom. 

MCT oil supplementation also led to lower PB serum concentrations and reduced liver enzyme activity, suggesting possible interactions affecting ASD pharmacokinetics. Elevated blood beta-hydroxybutyric acid (BHB) concentrations during MCT-DS periods were observed, aligning with previous studies. BHB has shown seizure-suppressing and neuroprotective effects in various models, and its elevation in dogs' blood might contribute to improved seizure control. 

The study faced limitations, such as uncontrolled baseline diets and small sample sizes, but indicated that MCT oil is a safe and potentially beneficial addition to epilepsy management in dogs. Further research is needed to explore its effects in drug-naive dogs or those with less drug-resistant epilepsy, as well as the broader implications for dietary management of epilepsy in both humans and canines. 

Berk BA, Law TH, Packer RMA, et al. A multicenter randomized controlled trial of medium-chain triglyceride dietary supplementation on epilepsy in dogs. J Vet Intern Med. 2020; 34: 1248–1259. https://doi.org/10.1111/jvim.15756 

Bottom line — MCT’s did lower seizure frequency.

Galliprant vs Metacam for Pain.

Management of mild to moderate pain in dogs often relies on nonsteroidal anti-inflammatory drugs (NSAIDs), commonly used for conditions like osteoarthritis, postoperative pain, and other inflammatory pain. However, NSAIDs are known to cause several adverse effects, particularly gastrointestinal issues, as well as kidney and liver damage. Traditional NSAIDs work by inhibiting cyclooxygenases (COX), which are involved in both inflammation and numerous physiological functions. Among these, prostaglandin E2 (PGE2) is a key proinflammatory agent that promotes pain through the EP4 receptor, particularly in osteoarticular systems. 

Grapiprant, an EP4 receptor antagonist, is approved for managing mild to moderate osteoarthritis pain in dogs and is thought to have a safer profile compared to traditional NSAIDs due to its targeted mechanism. Despite this, clinical evidence supporting grapiprant's efficacy is limited. One clinical trial showed that grapiprant decreased pain scores in dogs with osteoarthritis compared to a placebo. However, studies directly comparing grapiprant with conventional NSAIDs like meloxicam in postoperative joint surgery pain management are lacking. 

In a randomized, double-blind clinical trial, we compared grapiprant and meloxicam for managing postoperative pain in dogs undergoing TPLO surgery. Both drugs were effective in reducing pain postoperatively. However, due to the limited number of subjects and lack of baseline pain scores, it couldn't be conclusively determined if grapiprant was significantly better than meloxicam. Interestingly, grapiprant showed significant improvement in overall quality of life and orthopedic scores as assessed by owners and veterinarians. 

EP4 and EP2 receptors, the pharmacological targets of grapiprant, are overexpressed during chronic inflammation associated with conditions like osteoarthritis. While grapiprant is currently indicated for managing light to moderate osteoarthritis pain, its rapid action suggests potential benefits for acute or subacute pain management. However, its use in conditions other than osteoarthritis remains debated. Experimental studies have shown mixed results, with grapiprant being less effective than carprofen and firocoxib in certain models of acute arthritis. Nonetheless, in this study, grapiprant was comparable to meloxicam for managing postoperative pain, possibly due to differences in pain mechanisms between experimentally induced arthritis and surgical inflammation. 

Safety studies on long-term grapiprant administration indicate it is well-tolerated, though our study noted a higher incidence of digestive side effects, which may be attributed to anesthesia rather than the drug itself. The use of meloxicam prior to grapiprant in the grapiprant group could also have influenced these side effects. Another limitation was administering both oral treatments before meals, which may affect grapiprant's bioavailability. Additionally, pain assessment relied on the Canine Brief Pain Inventory (CBPI) rather than more objective measures, and baseline pain scores were not documented, introducing potential bias. 

Despite these limitations, our study suggests that grapiprant, administered daily at 2 mg/kg for 14 days, is at least as effective as meloxicam for managing postoperative pain in dogs with cranial cruciate ligament disease treated by TPLO. The better quality of life and orthopedic recovery observed with grapiprant highlights its potential as a viable alternative to conventional NSAIDs for postoperative pain management. However, the lack of demonstrated safety improvement and potential confounding factors necessitate further investigation. 

Cassemiche A, Schoffit S, Manassero M, Kohlhauer M. Comparison of grapiprant and meloxicam for management of postoperative joint pain in dogs: A randomized, double-blinded, prospective clinical trial. J Vet Intern Med. 2024; 38(4): 2324-2332. doi:10.1111/jvim.17136 

Bottom line — This study surprised me as this has not been my clinical experience.

Just putting things in perspective …