Monoclonal Antibodies for Dogs and Cats

Laurie Anne Walden, DVM

Photo by Anya Prygunova on Unsplash

In recent years, monoclonal antibodies have been approved to treat some common medical conditions in animals:

• Allergic itch in dogs (Cytopoint, Zoetis)
• Osteoarthritis pain in cats (Solensia, Zoetis)
• Osteoarthritis pain in dogs (Librela, Zoetis)
• Parvovirus infection in dogs (Canine Parvovirus Monoclonal Antibody, Elanco)

 
More monoclonal antibodies are likely to become available for dogs and cats. Monoclonal antibodies are used in humans to treat infections, autoimmune disorders, cancer, and other conditions, and they’re being investigated for similar uses in dogs and cats.
 
How Monoclonal Antibodies Work
Monoclonal antibodies are in a therapy class called biologics, meaning therapies made from living sources like animal cells, plant cells, or microorganisms. Biologics are large molecules that interact with receptors on the outer surfaces of cells; they don’t enter cells. In contrast, most traditional drugs are small molecules that work inside cells.
 
Monoclonal antibodies are similar to the natural antibodies produced by the immune system. When the immune system detects an antigen, different immune cells release lots of different antibodies that tag different sites on that antigen. (An antigen is anything that triggers an immune response.) Once the antibodies have tagged the antigen, other components of the immune system arrive to destroy it.
 
Monoclonal antibodies are cloned in a laboratory from just one antibody made by one type of immune cell (mono means “one”). They tag only a single site on an antigen. Monoclonal antibody therapy can be very precise because it directs the immune response to a narrow target.
 
In addition to tagging invaders like viruses, monoclonal antibodies can be engineered to tag a receptor on an animal’s own cells. The monoclonal antibodies that relieve pain in dogs and cats, for example, block production of a protein that’s partly responsible for the pain sensation.
 
After monoclonal antibodies have activated the immune system, they’re broken down in the body the same way that natural antibodies are. Unlike small-molecule drugs that enter an animal’s cells, they aren’t cleared through the liver or kidneys.
 
Administration
Monoclonal antibodies are given by injection at a veterinary clinic. They can’t be given by mouth because they’re proteins and would be destroyed by digestion. Their effect lasts a few weeks (4-8 weeks for Cytopoint, 4 weeks for Solensia and Librela). These therapies are species specific: monoclonal antibodies for dogs work only for dogs, not for cats.  
 
Benefits
The monoclonal antibodies that are available for dogs and cats generally work well for their approved uses. They are less likely than some traditional drugs to cause adverse effects because they have a narrow target of action and don’t enter cells. Because they are not cleared through the liver or kidneys, they can be safer than other drugs for animals with liver or kidney disease. Injections given every few weeks might be more convenient for pet owners than pills given multiple times a day, especially if their pets resist oral medication.
 
Adverse Effects
Monoclonal antibodies have fewer adverse effects than many traditional drugs. An antibody injection can cause an allergic reaction, although this is rare. Manufacturers might recommend precautions for individual monoclonal antibody products.
 
Image source: https://unsplash.com/photos/a-dog-wearing-a-baseball-glove-E3K7xyAvQ8M

---