Drug Therapy in Pet Rodents

<<Vet Med 93[11]:988-991 Nov'98 Review Article 10 Refs

Valarie V. Tynes, DVM
P.O. Box 510370 Punta Gorda, FL 33951

- Two primary challenges face veterinarians interested in caring for pet rodents. The first is purely financial. The more common pet rodents - guinea pigs, rats, mice, hamsters, and gerbils - are inexpensive to purchase and maintain. So most people who choose these rodents as pets do not spend much on veterinary care. For this reason, veterinarians must provide these animals the most economical treatment feasible. The second challenge stems from the patient's diminutive size. The doses of many medications used in rodents are so minute that some creativity may be required to dilute and properly administer them. Developing a good relationship with a local compounding pharmacist can be beneficial. The number of compounding pharmacists promoting their services to veterinarians is increasing, and most of these pharmacists will ship drugs anywhere in the country. Because the amounts of medication required are so small, the cost of these products is usually quite reasonable. Before treating pet rodents, inform your clients that the medication will be used in an extralabel fashion. Ideally, clients should sign a release acknowledging this fact. Few pharmacokinetic trials have been performed in rodents commonly kept as pets. This article is intended to provide small-animal clinicians basic information on drugs used to treat the more common conditions seen in pet rodents.
Because most referenced drug dosages for rodents are empirical, and wide dose ranges are often given, you may want to consult several references before choosing a drug or dosage for a pet rodent. Client education is also essential so owners will understand the importance of monitoring their pets closely, discontinuing medications at the first sign of side effects, and notifying their veterinarians of any problems. Many clients bond with their pet rodents and appreciate veterinarians' efforts to use the latest medical information when treating their animals. Despite he many challenges, treating pet rodents can be rewarding.


Included in the article are tables outlining dosage and route of administration of antimicrobials and miscellaneous drugs used in pet rodents.


VIN SUMMARY:

Two primary challenges, cost and patient size, face veterinarians. Pet rodents are quite inexpensive, thus veterinary care of any extent may cost more than an owner is willing to pay. Plus, patient size often requires minuscule amounts of medication, thus requiring dilution for proper administration. (And, since few drugs are labeled for rodents, owners should be informed of extra-label drug use and a signed release obtained.)

Antimicrobials

Antibiotics (oral, and sometimes topical) can cause fatal changes in intestinal microflora. (Gram negative bacteria overgrow and cause enterocolitis and diarrhea.) Oral lactobacillus supplements have been used to ameliorate the gastrointestinal side-effects, but their effectiveness is debatable.

Guinea pigs:

Fatal reactions can result from: penicillin, bacitracin, erythromycin, ampicillin, and chlortetracycline

Toxic reactions can result from: spiramycin, lincomycin, streptomycin, gentamicin, clindamycin, and vancomycin

Antibiotics generally considered safe (see table below): enrofloxacin, ciprofloxacin, chloramphenicol, cephaloridine, oxytetracycline, sulfamethazine, trimethoprim-sulfamethoxazole, and trimethoprim-sulfadiazine

Hamsters:

Fatal reactions: penicillin, streptomycin, dihydrostreptomycin, erythromycin, lincomycin, clindamycin, and tetracyline

Antibiotics generally regarded as safe (see dosage table below): trimethoprim-sulfamethoxazole, enrofloxacin, ciprofloxacin, gentamicin, chloramphenicol palmitate, and tetracycline

Rats and mice:

Fatal reactions: streptomycin, dihydrostreptomycin, procaine component of penicillins

Safe (see dosage table below): trimethoprim-sulfamethoxazole, enrofloxacin, ciprofloxacin, gentamicin, chloramphenicol palmitate, and tetracycline

For respiratory disease: tetracycline in drinking water (3 mg/ml) for 7 days, or enrofloxacin (10 mg/kg PO BID) plus doxycycline hyclate (5 mg/kg PO BID) for 7 days. *Both treatments may not be curative, but may aid suppression of the disease.

Gerbils:

Fatal reactions: streptomycin and dihydrostreptomycin

Antibiotics generally regarded as safe (see dosage table below): trimethoprim-sulfamethoxazole, enrofloxacin, ciprofloxacin, gentamicin, chloramphenicol palmitate, and tetracycline

Antimicrobials Used in Guinea Pigs
Agent Dose Route
Cephaloridine 15-25 mg/kg SID Subcutaneously
Chloramphenicol sodium succinate

* warn clients about hazards of use

50 mg/kg BID Subcutaneously
Chloramphenicol palmitate

* warn clients about hazards of use

50 mg/kg BID Orally
Ciprofloxacin 10 mg/kg BID Orally
Enrofloxacin 5 – 10 mg/kg BID or

100 mg/liter drinking water

Orally
Oxytetracycline 5 mg/kg BID Intramuscularly
Sulfamethazine 166 – 517 mg/ liter drinking water Orally
Trimethoprim-sulfadiazine 30 mg/kg SID Subcutaneously
Trimethoprim-sulfamethoxazole 15 mg/kg BID Orally

 

Antimicrobials Used in Hamsters, Gerbils, Rats, and Mice
Agent Dose Route
Chloramphenicol palmitate

* warn clients about hazards of use

50 mg/kg BID Orally
Ciprofloxacin 10 mg/kg BID Orally
Enrofloxacin 10 mg/kg BID or

100 mg/liter drinking water

Orally
Gentamicin 5 – 8 mg/kg SID Subcutaneously or intramuscularly
Tetracycline 20 mg/kg BID Orally
Trimethoprim-sulfamethoxazole 15 mg/kg BID Orally

Antiparasitics

Ivermectin is safe in most rodents for treatment of endoparasites and ectoparasites

Dosage: 200 – 400 m g/kg; two treatments, 10 days apart; subcutaneous or oral

Ivomec 1% solution: 1 part Ivomec + 19 parts propylene glycol = 1 mg ivermectin/2 ml solution

For large rodents: ivermectin equine paste (18.7 mg ivermectin/ml), orally or mixed with food

Pinworms in mice cause perineal pruritus and can be treated with: Ivermectin orally (2 mg/kg, two treatments given 10 days apart); other treatments include mebendazole orally (40 mg/kg two times, 7 days apart), thiabendazole orally (100 mg/kg once a week for 4 weeks), or piperazine citrate mixed with drinking water (200 mg/kg body weight SID for 7 days, wait 7 days, and repeat treatment).

Lime sulfur diluted 1:40 in water, applied as a dip once a week for 6 weeks

Sarcoptes mites in guinea pigs, rats, and hamsters

Fur mites in mice and rats

*Keep animals in a warm draft-free location after dipping

1% lindane baths, once a week for 3 weeks

Sarcoptes mites in guinea pigs

*Keep animals in a warm draft-free location after dipping

0.5% malathion dip, sponged on

Lice in guinea pigs and mice

NOT SAFE in preweanling animals

*Keep animals in a warm draft-free location after dipping

Amitraz: diluted with water according to package directions (wash animals at two-week intervals for 3 - 6 treatments), or diluted at five times the package directions for greater safety (1 bottle per 10 gallons water, and wash animals at two week intervals for 3 - 6 treatments)

Demodicosis in gerbils, hamsters, and rats

*Keep animals in a warm draft-free location after dipping

Flea powders, sprays, and foams approved for cats are usually safe

Lice, fur mites, fleas in guinea pigs, rats and mice

Thoroughly clean and sanitize the pet’s environment prior to returning it to that environment. Repeat thorough cleaning with each subsequent treatment.

Miscellaneous drugs for various conditions (see table below)

Dermatophytosis (Trichophyton mentagrophytes) is zoonotic. Treatment must include clearing the lesions and eliminating the organism from the environment (cage and accessories).

Griseofulvin is teratogenic and should not be used in pregnant animals

Rats: topical therapy of povidone-iodine (one-time) solution, followed by griseofulvin orally (25 mg/100 g body weight every 10 days for 3 doses

Guinea pigs: griseofulvin 15 – 75 mg/kg/day for 14 – 28 days (doses up to 100 mg/kg have been reported)

Topical antifungals applied SID for 2 – 4 weeks may be used for localized or mild disease

Hypovitaminosis C (scurvy) in guinea pigs can lead to secondary systemic and infectious diseases due to immunosuppression

All sick guinea pigs should be given supplementation (50 – 100 mg/day, injectable)

Normal supplementation dose: Vitamin C 200 – 400 mg/liter of drinking water

Vitamin C deteriorates rapidly in stored feed/water; fresh solutions should be made frequently

Organophosphate poisoning: treat with atropine

Anaerobic infection: treat with metronidazole

Warfarin poisoning: treat with vitamin K

Delayed parturition: treat with oxytocin

Miscellaneous Drugs Used in Pet Rodents
Agent Dose Route
Atropine 10 mg/kg q 20 minutes Subcutaneously
Balanced electrolyte solutions 10 ml/100 g body weight SID Subcutaneously, intravenously, intraosseously, intraperitoneally
Doxapram hydrochloride 2 – 5 mg/kg q 15 minutes Subcutaneously, intravenously, intraosseously
Epinephrine 0.02 – 0.2 mg/kg Intravenously, intraosseous bolus
Griseofulvin 15 -75 mg/kg SID Orally
Ivermectin 200 – 400 m g/kg Subcutaneously, orally
Metronidazole 20 mg/kg SID Orally
Oxytocin 0.2 – 3 units/kg Subcutaneously, intramuscularly
Vitamin C 200 – 400 mg/liter drinking water,

make fresh daily

Orally
Vitamin K 1 – 10 mg/kg PRN intramuscularly

Routes of Administration

Drinking water, as a route of administration, has many drawbacks. It is difficult to monitor consumption (especially if in multiple-animal housing), patients tend to drink less (or even none) because of taste and color, and desert dwellers always drink little (healthy or ill).

Antibiotics, if used in drinking water, must dissolve easily, mix well, and be changed daily. Deionized (not tap) water must be used.

Oral administration is cheaper and more convenient.

Parenteral administration is the most effective route, but usually costs more than oral. (Some owners can be taught to give injections at home.)

Educate clients to monitor closely, discontinue medications at any sign of side effects, and contact the veterinarian if any problems arise.


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vinid = JA013009, date1298
Journal info: ISSN 8750-7943; ID=J035, VM


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