Phenylbutazone/Cimetidine Paste

Paste medications are thick and sticky, usually given by mouth using a syringe or tube. They’re often used for dewormers or other oral meds in horses, dogs, and cats. The key is to aim for the back of the mouth so your pet swallows the paste instead of spitting it out.

For Horses:

1. Set the dose on the syringe if it has markings (usually based on weight).
2. Stand beside your horse, not in front, and have someone hold them if possible.
3. Gently insert your thumb into the side of the horse’s mouth (between the teeth) to open it.
4. Insert the syringe into that gap and squirt the paste toward the back of the tongue.
5. Lift the horse’s head slightly and encourage swallowing by stroking the throat or gently blowing on the nostrils.
6. Watch for licking or chewing—that means they swallowed. If paste spills out, check how much was lost and contact your vet if unsure.
7. You can offer a little water afterward and reward them with a treat like a carrot if allowed.

For Dogs & Cats:

1. Gently open your pet’s mouth or slip the syringe into the side of it.
2. Aim toward the back of the tongue and squirt the paste in.
3. Hold the mouth closed briefly, and rub the throat or blow gently on the nose to encourage swallowing.
4. Give praise or a treat afterward to make it a positive experience.

Aftercare:

1. Wipe your pet’s mouth if needed.
2. Clean or recap the syringe as instructed.
3. Store the tube according to label directions.

Tip: Paste can feel weird to pets at first. For horses, try giving applesauce by syringe ahead of time so they get used to the sensation.

This compounded formulation combines phenylbutazone, a non-steroidal anti-inflammatory drug (NSAID), with cimetidine, an H2-receptor antagonist — two different drug classes. In compounding practice, clinicians may consider a combination like this for a multi-targeted approach. Your veterinarian determines whether it is appropriate based on your animal's diagnostic findings.

At a pharmacological level, the two active ingredients function through distinct mechanisms. Phenylbutazone acts by inhibiting the cyclooxygenase (COX) enzymes, which are responsible for the synthesis of prostaglandins that mediate inflammatory responses. By reducing the production of these mediators, it addresses systemic and localized inflammation within the tissues. Cimetidine acts as a competitive inhibitor of histamine at the H2-receptors located on the gastric parietal cells. This action suppresses the secretion of gastric acid, providing a gastroprotective element to the protocol. This dual-action approach acts to address inflammatory concerns while managing the gastric environment. Your veterinarian will determine if this specific combination is appropriate based on your horse's weight, health status and individual clinical needs.

This description reflects the general pharmacology of the active ingredient's drug class; your veterinarian determines whether this approach is appropriate for your animal.

Prescription only. Use only under the direction of a licensed veterinarian. This information is not a substitute for veterinary diagnosis, prescribing or monitoring. Compounded drugs are not approved by the FDA for safety or effectiveness.

Commonly observed effects of phenylbutazone/cimetidine may include gastrointestinal changes such as loose stools, decreased appetite or transient behavioral shifts. Because phenylbutazone can influence renal blood flow and the mucosal lining of the gastrointestinal tract, your veterinarian will monitor for signs of gastric ulceration or changes in kidney function during the course of administration. Ensuring your horse remains well-hydrated and has access to appropriate forage is a critical component of the management approach.

This medication is typically used with extra caution or avoided in patients with known kidney or liver disease, pre-existing gastrointestinal ulcers or cardiac compromise. It is also carefully evaluated in pregnant or lactating mares, as the safety profile for developing foals has not been extensively characterized. Because cimetidine can inhibit certain liver enzymes, it may influence the metabolism of other oral medications, so a complete history of all current prescriptions and supplements is essential. Contact your veterinarian promptly if you observe any unexpected changes in water intake, swelling of the lower limbs or signs of abdominal discomfort. Always consult your veterinarian about the appropriate duration of use and whether your horse's competitive status requires a withdrawal period. Phenylbutazone (an NSAID) is subject to detection in equine medication-testing programs and specific withdrawal times vary by jurisdiction and governing body.