ISSN 2398-2985      

Drug administration techniques

6guinea pig

Introduction

Rationale for technique

  • Drug administration can be by injection (subcutaneous (SC), intramuscular (IM), intraperitoneal (IP), intravenous (IO)) or oral routes.
  • Intraosseous catheterization is detailed in another technique Intraosseous catheterization. Most drugs that are given IV can be given IO, except for hypertonic or alkaline solutions, which should be diluted when possible.
  • Nasogastric, pharyngeal or oral gastric tubes are rarely used in guinea pigs for medication administration as these are difficult to place due to the presence of the ostium (paranasal sinus openings): placement of a tube requires passage through the ostium into the esophagus by directly visualizing the placement. This is usually done with an endoscope and requires anesthesia.

Uses

Advantages
  • Injections deliver medication parenterally and therefore are not dependent on a functioning gastrointestinal tract for absorption.
  • Oral administration may be easier, but if there is gastrointestinal problems, there may be complications of absorption and/or disruption of the gut flora Gastrointestinal stasis Diarrhea. Gut flora can potentially be disrupted by any oral medication.
  • The SC route works well for larger volumes such as with fluid therapy Fluid therapy guidelines.
Disadvantages
  • Skin is thick in the upper back and requires a larger needle (larger than 25 ga).
  • Small muscle masses including lumbar and anterior thighs for IM injections limits volume.
  • IV administration is difficult due to the small veins (saphenous, cephalic, ear). If a catheter is placed in the jugular vein, it requires a cut-down procedure to install it. The ear veins are very small, but may be a route to deliver emergency medications such as might happen during surgery. Ear veins may develop hematomas readily. The author would use this route only in an emergency. The penile vein can also be used in anesthetized males. It is usually only used in an emergency.
  • IP injections can be done in the hospital, but is not a route for owners to medicate the guinea pig at home. Training of the veterinarian and staff on this technique also takes some practice.
  • IO catheter placement requires heavy sedation and/or anesthesia for placement Intraosseous catheterization.
  • The oral route must be used with caution in the dyspneic guinea pig. If there is oral/dental disease Dental disease, the guinea pig may resist having a syringe inserted into the mouth with medication.
  • Most guinea pigs will vocalize Vocalization behavior loudly when injected.
Most drugs are not licensed to be used in guinea pigs.

Technical problems

  • Proper restraint is required for injections and oral medicating.
  • Volume for IM injection should not exceed 0.5 mL in any one site. Irritating solutions should not be used.
  • Volume for IP injections should not exceed 8 mLs. The solution should be warmed to body temperature and not be irritating (very high or low pH).
  • A maximum volume of 5-10 mLs is used for each SC site.

Alternative techniques

  • IO catheter placement is more practical than placing an IV catheter for fluid and medication administration Intraosseous catheterization.
  • Nebulization: allows delivery of drugs such as antibiotics, antifungals and mucolytic agents to the upper and lower airways and the lung parenchyma.
  • Intranasal administration: sedatives such as midazolam Midazolam can be administered intranasally.
  • Antibiotic impregnated beads, tape, gel or gauze: for application to infected sites. Similarly, some abscesses can be treated with topical application of honey or calcium hydroxide.
  • Intratracheal: for emergency drugs such as atropine Atropine or epinephrine Epinephrine. Increase normal IV dose by 2 or 2.5-fold when given intratracheal.
  • Vascular access devices are indicated for long-term, frequent delivery of chemotherapeutics or antimicrobials. As an example, it may be useful to treat lymphoma in guinea pigs.
  • Transdermal: transdermal administration of some insecticides has several advantages, eg increased client compliance, ease of delivery, bypass of routes of metabolism.
  • Epidural: for chronic pain or abdominal, hindlimb or perineal surgery.

Time required

  • Injections (SC, IM, IV or IP) can be done rapidly.
  • Oral administration is usually fairly quick unless the guinea pig fights the restraint and resists having a syringe placed in its mouth.
  • IO administration is rapid, however the procedure itself may take 15 min or longer for sedation/anesthesia to be induced.
Preparation
  • Filling syringes is rapid (see individual active ingredients for calculations of dosages for guinea pigs).
  • Oral medications should be palatable; many of these will be compounded from tablets and a sweetened pharmaceutical compounded solution can be used. Guinea pigs like apple, berry, orange and peanut butter flavors.
  • Guinea pig can be restrained via holding or being wrapped in a towel Restraint.
Procedure
  • Injections themselves are rapid.
  • Oral medications placed directly in the mouth takes under a minute unless the guinea pig fights having medications placed in the mouth.

Decision taking

Criteria for choosing
  • Type of medication and route must allow for the best absorption of a particular medication.
Risk assessment
  • Anesthesia or heavy sedation with local anesthesia are needed for IO catheter placement. Anesthesia is always a risk in guinea pigs, and especially in ill cavies.
  • Injection solution itself may cause muscle damage (such as enrofloxacin Enrofloxacin) and the volume and frequency of delivery may limit the IM injections in particular that can be given.
  • Restraint and the momentary pain of injection with any route can cause stress.
  • IP injections should not be given if there is abdominal distention or gastrointestinal distress or disease. If the guinea pig is having respiratory problems (such as dyspnea Dyspnea), the position for IP injections can exacerbate breathing difficulties and should probably be avoided.

Requirements

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Preparation

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Procedures

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Aftercare

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Hawkins M G & Graham J E (2007) Emergency and critical care of rodents. Vet Clin Exot Anim 10 (2), 501-531 PubMed.
  • Klaphake E (2006) Common rodent procedures. Vet Clin Exot Anim 9 (2), 389-413 PubMed.
  • Powers L V (2006) Techniques for drug delivery in small mammals. J Exotic Pet Med 15 (3), 201-209.

Other sources of information

  • Quesenberry K E, Donnelly T M & Mans C (2012) Biology, Husbandry and Clinical Techniques of Guinea Pigs and Chinchillas. In: Ferrets, Rabbits and Rodents: Clinical Medicine and Surgery. 3rd edn. Eds: Quesenberry K E & Carpenter J W. Elsevier. pp 279-294.
  • de Matos R (2009) Rodent Therapeutics. In: BSAVA Manual of Rodents and Ferrets. Eds: Keeble E & Meredith A. BSAVA. pp 52-62.
  • Sirois M (2005) The Guinea Pig. In: Laboratory Animal Medicine: Principles and Procedures. Elsevier Mosby. pp 115-138.

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