Treatment of Pain in Birds

This article provides an overview of the current understanding of evidence-based clinical analgesic use in birds. The field of avian analgesia has dramatically expanded during the last 20 years, affording more options for alleviating both acute and chronic pain. These options include opioids, nonsteroidal anti-inflammatory drugs, local anesthetics, and/or other drugs like gabapentin, amantadine, and cannabinoids, acting at different points in the nociceptive system thereby helping to provide greater pain relief while reducing the risk of adverse effects when combined.

A Critical Review of the Pharmacokinetics and Pharmacodynamics of Opioid Medications Used in Avian Patients

Opioid drugs are used to manage moderate to severe pain in mammals and avian species. In dosing opioids for a particular species, it is optimal to use dosing regimens based on pharmacokinetics or pharmacodynamics studies conducted in the same species as variability in the physiology among different species may result in differences in drug pharmacokinetics and pharmacodynamics. Unfortunately, dosing regimens are typically extrapolated from closely related avian species or even mammals, which is unideal. Therefore, this critical review aims to collate and evaluate the dosing regimens of selected opioids: tramadol, hydromorphone, buprenorphine, butorphanol, and fentanyl, in avian species and its related safety, efficacy and pharmacokinetic data. Our review found specific dosing regimens not described in the Exotic Animal Formulary for tramadol used in Indian Peafowl (Pavo cristatus), Muscovy Duck (Cairina moschata) and Hispaniolan Parrot (Amazona ventralis); hydromorphone used in Orange-winged Parrot (Amazona amazonica); buprenorphine used in Cockatiel (Nymphicus hollandicus), American Kestrel (Falco sparverius) and Grey Parrot (Psittacus erithacus); and butorphanol used in Hispaniolan Parrot (Amazona ventralis), Broiler Chicken and Indian Peafowl (Pavo cristatus). Cockatiel appeared to not experience analgesic effects for hydromorphone and buprenorphine, and American Kestrel exhibited sex-dependent responses to opioids. The selected opioids were observed to be generally safe, with adverse effects being dose-dependent.

Advances in Therapeutics and Delayed Drug Release

Reducing the frequency of drug administration in the treatment of exotic pets is advantageous because it may decrease handling frequency and thus potential stress and injury risk for the animal, increase owner compliance with the prescribed treatment, and decrease need for general anesthesia in patients that cannot be handled safely. Increasing efficient drug plasma concentration using sustained-released delivery systems is an appealing solution. Potential candidates that could provide a promising solution have been investigated in exotic pets. In this article, the technologies that are the closest to being integrated in exotic pet medicine are reviewed: osmotic pumps, nanoparticles, and hydrogels.

Sustained-Release Injectable Hydrogel Formulations for Administration of Sodium Salicylate in Broiler Chickens

We developed injectable hydrogels for the slow release of analgesic drugs in birds as an in vivo model of pharmacokinetics in wild avian species. Hydrogels loaded with sodium salicylate (NaSA) were injected subcutaneously in Ross broiler chickens. The hydrogels were made by dissolving sodium alginate and NaSA in water at 2 different concentrations (low, LALG; high, HALG) and then adding calcium chloride. In vitro drug release studies were performed by swelling the hydrogels in water and analyzing serial samples by ultraviolet-visible (UV-Vis) spectroscopy. Dried hydrogel films of the same formulations of the two alginate concentrations then were dissolved in sterile water for the in vivo pharmacokinetic study conducted in 18 chickens divided into 3 groups of 6 birds. Each of the 2 resultant NaSA hydrogel solutions were filtered with 0.2-µm syringe filters before injecting at a NaSA dose of 150 mg/kg SC in the respective LALG or HALG groups. The control group was injected SC with the same dose of NaSA dissolved in water. Pharmacokinetics parameters calculated by the compartmental and noncompartmental approaches were compared among the 3 groups by the Kruskal-Wallis test. Results of in vitro studies showed that both hydrogels released 80% of the drug during the first 3.5 hours. Results of the pharmacokinetic study indicated that NaSA concentrations remained above the minimum effective concentration (MEC) for analgesia in humans for 24 ± 8.9 (LALG) to 26 ± 4 (HALG) hours for the hydrogel formulations compared to 10 ± 5.6 hours for the aqueous formulation. These hydrogel formulations may have potential in providing long-term analgesia in avian species, but need further evaluation with pharmacodynamic or pharmacokinetic/pharmacodynamic modeling studies.

Overview of Drug Delivery Methods in Exotics, Including Their Anatomic and Physiologic Considerations

Drug delivery to exotic animals may be extrapolated from domestic animals, but some physiologic and anatomic differences complicate treatment administration. Knowing these differences enables one to choose optimal routes for drug delivery. This review provides practitioners with a detailed review of the currently reported methods used for drug delivery of various medications in the most common exotic animal species. Exotic animal peculiarities that are relevant for drug administration are discussed in the text and outlined in tables and boxes to help the reader easily find targeted information.

Pharmacokinetics of butorphanol tartrate in a long-acting poloxamer 407 gel formulation administered to Hispaniolan Amazon parrots (Amazona ventralis)

OBJECTIVE To determine pharmacokinetics of butorphanol tartrate incorporated into poloxamer 407 (P407) after SC administration to Hispaniolan Amazon parrots (Amazona ventralis). ANIMALS 11 adult Hispaniolan Amazon parrots (6 males and 5 females; 11 to 27 years old). PROCEDURES A sterile formulation of butorphanol in P407 (But-P407) 25% (percentage determined as [weight of P407/weight of diluent] × 100]) was created (8.3 mg/mL). Five preliminary experiments (2 birds/experiment) were performed to determine the ideal dose for this species. The formulation then was administered (12.5 mg/kg, SC) to 8 birds. Blood samples were collected before (time 0) and 0.08, 0.5, 1, 2, 4, 8, 12, and 24 hours after drug administration. Some birds were used more than once, with a washout period of ≥ 3 months between subsequent treatments. Butorphanol concentrations were quantitated by use of liquid chromatography-tandem mass spectrometry. Pharmacokinetic analysis was performed by use of noncompartmental analysis. RESULTS Maximal plasma butorphanol concentration was reached at 1.31 hours. Plasma concentrations of butorphanol remained > 100 ng/mL for > 3 hours (all birds) or > 4 hours (5/8 birds) but < 8 hours (all birds). Half-life of the terminal slope was 3.41 hours. No adverse effects were detected. CONCLUSIONS AND CLINICAL RELEVANCE Butorphanol was absorbed well from the But-P407 25% by Hispaniolan Amazon parrots, and absorption followed a pharmacokinetic profile compatible with a sustained-release drug. A dose of 12.5 mg/kg, SC, would theoretically provide analgesia for 4 to 8 hours. No adverse effects were detected. Studies on the pharmacodynamics of this formulation are necessary to confirm the degree and duration of analgesia.

Reproductive Disorders in Commonly Kept Fowl

Backyard poultry and other commonly kept fowl species are often kept for their ability to lay eggs. Reproductive disease is common in fowl species. Despite being classified as food-producing species, they can be considered valuable pets, and the demand for adequate veterinary care is constantly increasing. The clinician should be familiar with the different abnormalities and the potential treatment options. Fowl species have been traditionally an anatomic, physiologic, and experimental model for avian medicine; however, information about treatment options is often limited and extrapolated from other species.