Yesterday I saw a post on a Facebook LP group about Librela for the first time. Since this is a big issue in the US, I’d like to share some of the issues here because I don’t know whether they’re being discussed anywhere else.

First, the veterinary community in the US and Great Britain has generally accepted as fact that the root cause of age-related LP is neurological. The disease is referred to as Geriatric-Onset Laryngeal Paralysis and Polyneuropathy (GOLPP) and is generally ascribed to neurological degeneration of the trunk vagus nerve, which governs muscular activity for a variety of systems including the larynx, esophagus, and cardiovascular system reaching all the way back to the hind end. Hence, LP and progressive hind end weakness are considered two sides of the same coin, i.e., progressive polyneuropathy.

Librela is a drug developed specifically to treat osteoarthritis in dogs and cats. It works by blocking the activity of a certain protein, called Nerve Growth Factor or NGF. As described by the US FDA:

Bedinvetmab, the active ingredient in Librela, works by binding to and inhibiting the biological activity of a protein called canine nerve growth factor (NGF), which has been found to be elevated in dogs with OA and is involved in the regulation of pain. When bedinvetmab binds to NGF, it prevents the pain signal from reaching the brain.

This is problematic for dogs with LP because many veterinary specialists postulate that NGF and neurological disease are in fact interrelated. It’s not surprising that Librela research was limited to animals who suffer from osteoarthritis pain but are otherwise healthy. Zoetis, the manufacturer of Librela, did no research focusing on Librela in animals with any pre-existing conditions, neurological or otherwise.

This is the way drug trials are done in the pharmaceutical environment under the auspices of the US FDA (Food and Drug Administration). The objective of corporate-funded research is to isolate variables to determine the efficacy of a drug for a specific condition. If the drug is efficacious for that specific condition, then the drug is approved for use for that specific condition, whereby the manufacturer is required to clearly state in the labeling that the drug is only approved for that specific condition, and not for animals with pre-existing conditions which may be affected by this drug.

What’s important here is not what Librela is approved for, but what it isn’t approved for, and it is specifically not approved for animals with preexisting neurological conditions — in other words, conditions such as LP or GOLPP. This fact is most often whitewashed by primary veterinarians who have insufficient understanding of LP and choose instead to buy into the sales pitch of their pharmaceutical representative. And what they are told is this: Librela is great for osteoarthritis, end of story. Unfortunately, US veterinarians have little time to second-guess pharmaceutical labelling. They are under great stress to provide immediate results. They’re not in the business of doing research and depend on their pharma reps to provide accurate product information. However, the connection between NGF and neurological dysfunction is not lost on all veterinarians, and the voices of the sceptics are getting louder:

“Dr. David Dycus, an orthopedic surgeon in Severn, Maryland, concurs that the risk of patients suffering from side effects may be higher if they have other conditions in conjunction with osteoarthritis, such as neurological disease, for which the body may need NGF for repair.

‘Like any new drug that hits the market, once it gets to the masses, we're going to see things come up that maybe weren’t noted initially, or that weren’t necessarily thought were going to occur,' Dycus said.

'And something a lot of people have missed the boat on here is that in Zoetis’s safety studies, the animals really didn’t have comorbidities. So we can’t say that we know what the outcome would be in all animals because some have certain disease conditions that the treatment was never studied in.’" (https://news.vin.com/default.aspx?pid=210&catId=614&Id=12137959))

But the most disturbing fact about Librela is that in the US, a class action lawsuit has been filed by shareholders against Zoetis for misrepresentation and failure to disclose information. This comes in the wake of thousands of reports of dogs and cats suffering debilitating or fatal side-effects of Librela due to neurological or other unknown causes. There are currently multiple English-language Facebook groups (for instance LIBRELA - The TRUTH | Facebook) and one German language Facebook group (Librela Zoetis Erfahrungen | Facebook) for users to share experiences with Librela. Participants include veterinarians and animal owners who praise the benefits of Librela as well as users who share details of tragic suffering and loss of life.

What stands out is that veterinarians who prescribe Librela generally don’t inquire about preexisting neurological conditions, but instead only focus on whether the animal suffers from osteoarthritis. This is contrary to the best interest of the animal. Clearly, any human doctor who prescribed a medication without first inquiring about potentially conflicting preexisting conditions would soon be without a license and be looking for a different job.

For my part, I refused Librela for my 15-year-old Labrador although my primary veterinarian gave me the hard sell and refused to answer my questions about neurological side effects. My impression was that this veterinarian either 1) does not take GOLPP seriously and does not consider it a disease 2) is unaware of the the details of how Librela works 3) Doesn't really care about my old dog and is more interested in the $80 per shot. In all three of these cases, I consider this person to be 1) a bad example for veterinarians and 2) a bad example of an animal lover.

Unfortunately, in our small town there are very few alternatives, and this is par for the course for the average primary veterinarian – sell the product, don't ask questions, and if the dog get sick or dies, then it's not because of Librela but rather due to the mortality of living creatures, particularly old ones that need Librela. This is beyond crass. Librela is a relatively new, novel product and anyone who sells it has the duty to inform themselves about it and not immediately hop on the bandwagon. I know that Librela is being prescribed in the two clinics most mentioned in one Facebook group as being ‘the best’. Maybe ‘the best’ just doesn't necessarily mean ‘the best informed’.

From my perspective as an LP dog owner, LP is a severe neurological illness that is very little understood, therefore every LP dog is in a precarious position in which any medication could tip the balance that worsens their condition. Under no circumstances would I rock that boat with any drug that has not specifically undergone extensive testing in this context. Why? Because osteoarthritis and GOLPP obviously both afflict older dogs, so there is a high likelihood that these conditions will coexist. Any idiot can see that. Not being idiots, Zoetis knew it, and it had the responsibility to include animals with neurological degeneration in their product testing, not exclude them, or at least to do a subsequent study focusing on dogs with existing polyneuopathy. By not doing so, they proved themselves negligent, and I hope they suffer severe consequences in the courts that go beyond just a hit to their reputation. Because our dogs may be old, but that doesn't mean we love them any less.