Veterinary Pharmacology Glossary

Reference glossary of terms used across the ExoticRx formulary and articles. Anchored — link directly to a term with /glossary#<term-id>.

Dosing notation

q-intervals (q12h, q24h, q48h, q72h): Standard veterinary dosing-interval notation. q12h means once every 12 hours; q48h every 48 hours, and so on. Reptile and avian protocols commonly use longer intervals (q48–72h) than mammals because of slower clearance — do not shorten intervals to a familiar mammalian schedule without species-specific evidence.
PRN(Pro re nata): Latin: “as the situation demands.” Indicates the drug should be given only when clinically required (e.g. analgesic PRN for breakthrough pain), not on a fixed schedule.

PO(Per os): Latin: “by mouth.” Oral administration.
IM(Intramuscular): Injection into a muscle. In reptiles and birds, IM administration in the caudal half of the body engages the renal portal system; for nephrotoxic drugs, prefer cranial-half sites (pectoral muscle in birds, epaxial muscle anterior to mid-body in reptiles).
IV(Intravenous): Injection into a vein. In reptiles, the ventral coccygeal vein (tail vein) is the most common access; in birds, the right jugular vein is largest and most accessible.
SC / SQ(Subcutaneous): Injection under the skin. Slower absorption than IM.
ICoel(Intracoelomic): Injection into the coelomic cavity in reptiles, birds, and amphibians — the analogue of intraperitoneal in mammals. Common route for fluid therapy in these species.

PK(Pharmacokinetics): The study of how a drug moves through the body — absorption, distribution, metabolism, excretion (ADME). Species-specific PK data is the gold standard for dose-rule confidence.
PD(Pharmacodynamics): The study of what a drug does to the body — receptor binding, dose-response, mechanism of action.
TDM(Therapeutic Drug Monitoring): Measurement of plasma drug concentration to guide dosing, particularly for narrow-therapeutic-index drugs (aminoglycosides, antifungal triazoles in psittacines, anticonvulsants). Increasingly used in exotic-animal practice for prolonged courses.

Evidence: Strong: Species-specific peer-reviewed pharmacokinetic data or large clinical case series support the dose. Highest-confidence tier in the ExoticRx formulary.
Evidence: Moderate: Species-specific case series or established expert consensus support the dose. Reasonable confidence; clinical response should still guide individual dosing.
Evidence: Weak: Small case series or single-author opinion. Clinical use is reasonable in absence of stronger evidence but warrants close monitoring.
Evidence: Anecdotal: Clinical reports without formal peer review. Use with caution; consider alternatives where they exist.
Evidence: Extrapolated: Dose derived from related species without species-specific data. The lowest- confidence tier; particularly common in less-studied species. Document the clinical reasoning and monitor carefully.

CRI(Constant Rate Infusion): Continuous IV administration of a drug at a fixed rate, used for anesthesia adjuncts (lidocaine, ketamine, fentanyl) and ongoing analgesia. Common in exotic-pet emergency and surgical practice.

POTZ(Preferred Optimum Temperature Zone): The range of body temperatures at which a given reptile species' physiology operates normally. Drug metabolism is temperature-dependent in ectotherms; reptiles outside their POTZ will under-respond to even an appropriately chosen drug. Confirm husbandry and basking-spot temperatures before adjusting dose.
MBD / NSHP(Metabolic Bone Disease / Nutritional Secondary Hyperparathyroidism): The most common husbandry-driven disease in pet reptiles, particularly bearded dragons. Caused by inadequate dietary calcium, inadequate UV-B for vitamin D3 synthesis, or both. Clinical signs include skeletal deformity, pathological fractures, hypocalcaemic seizures, and tetany. Management combines calcium supplementation, husbandry correction, and acute treatment of hypocalcaemia where present.
Dysecdysis: Abnormal or incomplete shedding in reptiles, often secondary to inadequate humidity, ectoparasitism, or systemic disease. Stuck shed on tail tips, toes, or spectacles can cause necrosis if untreated. Address the underlying husbandry problem in addition to physical removal.

Renal portal system: Anatomical pathway in reptiles and birds where venous blood from the caudal half of the body passes partially through the kidneys before reaching systemic circulation. Clinically, drugs delivered to the leg or tail may suffer first-pass renal extraction; for nephrotoxic drugs (especially aminoglycosides like Amikacin), use cranial-half injection sites.

Psittacine: Member of the parrot order (Psittaciformes) — includes parrots, cockatoos, macaws, conures, parakeets, budgerigars, lovebirds, and lorikeets. Avian pharmacology distinguishes psittacines from non-psittacine pets (raptors, passerines, waterfowl) because of differences in metabolism and disease susceptibility.
PBFD(Psittacine Beak and Feather Disease): Viral disease of psittacines caused by beak and feather disease virus (BFDV), characterised by progressive feather dystrophy, beak deformity, and immunosuppression. No specific antiviral; supportive care and isolation from unaffected birds.
Chlamydiosis (avian)(Psittacosis): Zoonotic infection caused by Chlamydia psittaci, common in psittacines. First-line treatment is Doxycycline for a 45-day course (not the 7–14 days familiar from canine practice). Owner counselling on zoonotic risk is mandatory.

Obligate hindgut fermenter: Animal whose caecum and colon contain a microbial fermentation chamber essential to nutrient absorption. Rabbits, guinea pigs, chinchillas, and horses are obligate hindgut fermenters. Oral antibiotics that selectively destroy gram-positive flora (penicillins, oral cephalosporins, clindamycin, oral macrolides) cause fatal dysbiosis in rabbits and guinea pigs. See antibiotic selection.
E. cuniculus(Encephalitozoon cuniculus): Microsporidian parasite endemic in pet rabbit populations (40–70% seroprevalence). Clinical syndromes include vestibular signs, posterior paresis, renal disease, and phacoclastic uveitis. Treated with Fenbendazole for 28 days. See the full clinical guide.