Fish Zole: Metronidazole 250mg


The Side Effects of Metronidazole in Dogs


updated: May 06, 2010

Metronidazole is a useful antibiotic often prescribed as Flagyl. While it is considered fairly safe, this drug has been known to have side effects. Some dogs taking this drug, either on its own, in combination with other drugs, or while afflicted with another condition than the one being treated, have experienced negative reactions that range from mild to worrisome, to permanent or fatal. This medication should not be given to puppies or pregnant dogs.

  1. Benefits

    • Metronidazole effectively fights anaerobic infections, infections growing without the presence of oxygen. Anaerobic bacterias cause infections that occur at surgery sites, in the mouth, the gastrointestinal tract, deep wounds or tissues, the vagina and internal organs. As an antibiotic, it fights against certain gastrointestinal parasites, especially Giardia.

      Metronidazole is also used successfully as an anti-inflammatory drug, particularly in the large intestine, where it counteracts nonspecific diarrhea and treats irritable bowel syndrome. Veterinarians prescribe this drug for periodontal disease, tetanus and pancreatic insufficiency with small intestinal bacterial overgrowth (SIBO).

    Common Side Effects

    • Metronidazole is usually tolerated better if given with food because it can be bitter and dogs may develop an aversion to it. The most common side effects in dogs are reactions to the bitter taste, mild stomach upset and decreased appetite. When taking it, some dogs exhibit excessive salivation, gagging, reflux, mouth pawing, nausea or vomiting.

    Less Common Side Effects

    • More serious, less common side effects of Metronidazole include diarrhea, depression, weakness, low white blood cell count, blood in the urine and liver complications. Signs of toxicity, if present, tend to begin 7 to 12 days after the beginning of treatment. In most cases, these side effects resolve in a matter of days after stopping the medication.

    Neurological Side Effects

    • Some dogs suffer from neurological side effects, such as nystagmus (unintentional eye movement), dilated pupils, ataxia (lack of coordination) head-tilt, tremors, disorientation, stiffness and even seizures. These more alarming symptoms may be seen in dogs who have been prescribed long-term moderate to high-dose therapy for treatment of difficult bacterial infections like SIBO.
      One neurologist examining a symptomatic dog informed the dog's owner that he rarely saw a dog with Metronidazole toxicity return to normal and that some had permanent brain damage. Although dogs compensate and learn to live with acquired disabilities, these neurological symptoms can worsen when a dog is sick or stressed.

    Cases of Metronidazole Toxicity

    • SIBO is one of those stubborn conditions. Dogs who have it may require long-term Metronidazole treatment, and some have experienced serious side effects.

    Pre-existing Conditions

    • Before you give your dog Metronidazole, make sure your veterinarian knows what other drugs your dog has been taking. Your dog's liver function should be tested and monitored, and, if your dog already has liver disease, it should not be prescribed.
      There is a possibility that dogs with tick-related diseases may be more susceptible to Metronidazole toxicity, because both can affect liver function.

    Diagnosis, Treatment and Prognosis

    • There are no home remedies for Metronidazole poisoning. If you even suspect this drug as a possible cause for symptoms your dog is exhibiting, immediately contact your veterinarian or an emergency animal clinic.
      Diagnosis of metronidazole toxicity is based on a physical exam and a thorough history of recent drug intake and pre-exisiting conditions. Blood tests to measure the toxicity of this drug have not been shown to be effective.
      The initial treatment for Metronidazole toxicity is immediate withdrawal of the drug. Some dogs may need to be hospitalized and given intravenous fluids as well as intravenous Diazepam. An emetic to stop vomiting may also be needed. Blood tests should be conducted to evaluate the function of the dog's liver and kidneys.
      There is no known antidote for Metronidazole poisoning, and recovery may take 1 to 2 weeks or longer. Unfortunately, dogs who are severely affected may not survive

Read more: The Side Effects of Metronidazole in Dogs |

Fish Mycin: Erythromycin 250mg 

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  • Erythromycin is an antibiotic that inhibitsbacteria by suppressing protein synthesis and growth. Other related medications include azithromycin (Zithromax®) and clarithromycin (Biaxin®).
  • Erythromycin is effective against a narrow range of bacteria in dogs and cats. It is effective against bacteria that infect the skin, respiratory tract and sinuses. Erythromycin is not effective against intestinal-origin coliform bacteria (E. coli, for example). 
  • Erythromycin is a prescription drug and can only be obtained from aveterinarian or by prescription from a veterinarian.

    Brand Names and Other Names

  • This drug is registered for use in animals and humans.

  • Human formulations: Ery-Tab® (Abbott), E-Mycin® (Boots) and Robimycin® (Robins) 
  • Veterinary formulations: Erythro-100® (Rhone Merieux)

    Uses of Erythromycin

  • Erythromycin is used in both dogs and cats to treat bacterial infections, including skin infections, wound infections, bone infections, pneumonia and sinus infections. It also has been used for some tick-borne infections, such as Lyme disease. 
  • Erythromycin at low doses has been used to stimulate intestine motility, but the application of this effect for treating diseases is not established.
  • Erythromycin is not effective against infections caused by parasites (intestinal worms), mites, viruses or fungi.

    Precautions and Side Effects

  • While generally safe and effective when prescribed by a veterinarian, erythromycin can cause side effects in some animals.
  • Erythromycin should not be used in animals with known hypersensitivity or allergy to the drug.
  • Erythromycin may interact with other medications. Consult with your veterinarian to determine if other drugs yourpet is receiving could interact with erythromycin. Such drugs include theophylline, digoxin, methylprednisolone and certain antibiotics.
  • The most common side effect is vomiting. Dogs particularly may vomit shortly after administration of erythromycin. If this reaction is observed, it is usually not serious.
  • Erythromycin may cause nausea, diarrhea and decreased appetite in dogs and cats. 
  • Erythromycin has caused liver reactions in people, however these have not been a problem in animals. Do not administer erythromycin to pregnant animals.

    How Erythromycin Is Supplied

  • There are many formulations of erythromycin available as various chemical compositions (salts, esters, etc.). Common formulations include tablets and capsules in sizes ranging from 250 mg to 500 mg. Oral liquid suspension ranges in concentration from 25 mg/ml to 50 mg/ml. 
  • The base of erythromycin is sometimes supplied in an enteric-coated tablet. These tablets are not absorbed from the stomach or intestine in animals very well and should not be administered for therapy.

    Dosing Information

  • Medication should never be administered without first consulting your veterinarian. 
  • The usual dose is 5 to 10 mg per pound (10 to 20 mg/kg) every eight to 12 hours orally.
  • The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your pet feels better, the entire treatment plan should be completed to prevent relapse or prevent the development of resistance
  • Fish Fungus: Ketoconazole 200mg 

    GENERIC NAME: ketoconazole

    BRAND NAME: Nizoral, Extina, Xolegel, Kuric

    DRUG CLASS AND MECHANISM: Ketoconazole is an anti-fungal medication in the same family of drugs as fluconazole (Diflucan), itraconazole (Sporanox), andmiconazole (Micatin, Monistat). It prevents growth of several types of fungi by preventing production of the membranes that surround fungal cells. The FDA approved ketoconazole in June 1981.



    PREPARATIONS: Tablets: 200 mg; Shampoo: 1 and 2%; Cream: 2%, Gel: 2%, Foam: 2%

    STORAGE: Tablets should be stored at room temperature, 15-25 C (59-77 F) and protected from moisture.

    • Store shampoo 1% between 2-30 C (35-86 F) and protect it from light and freezing.
    • Store shampoo 2% at or below 25 C (77 F) and protect it from light.
    • Store cream and foam at room temperature, 20-25 C (68-77 F).
    • Store gel between 15-30 C (59- 86 F).

    PRESCRIBED FOR: Oral ketoconazole treats a variety of fungal infections such ascandidiasis of the skin or mouth (thrush), blastomycosishistoplasmosis,coccidiomycosis, and others. Ketoconazole is also used to treat fungal infections that have not responded to griseofulvin, another antifungal medication. Topical ketoconazole is used for treating ringwormjock itchathlete's footdandruff, andtinea versicolor.

    DOSING: Ketoconazole may be taken with or without food. The oral dose range is 200-400 mg daily. Topical formulations are administered to affected areas once or twice daily.

    DRUG INTERACTIONS: There are no known drug interactions with topical ketoconazole.

    Ketoconazole tablets require stomach acidity to dissolve. Therefore, ketoconazole should be administered at least two hours before taking antacids or other acid reducing medications such as cimetidine (Tagamet) or ranitidine (Zantac). Combining ketoconazole with alcohol may cause a very unpleasant reaction (disulfiram reaction).

    Rifampin (RifadinRimactaneRifamateRifater) reduces the blood concentration of oral ketoconazole, probably by increasing the elimination of fluconazole by the liver. This may reduce the effectiveness of ketoconazole.

    Ketoconazole may increase the concentration of warfarin (Coumadin) in blood by reducing the elimination of warfarin. Therefore, the effect of warfarin may increase, leading to an increased tendency to bleed.

    Ketoconazole also increases the concentration of phenytoin, (Dilantin) cyclosporine, zidovudine (Retrovir), theophylline (Theo-Dur, Respbid, Slo-Bid, Theo-24, Theolair, Uniphyl, Slo-Phyllin), tolbutamide, glyburide (Micronase, Diabeta, Glynase), glipizide (Glucotrol), protease inhibitors [for example, indinavir (Crixivan),ritonavir (Norvir), saquinavir (Invirase, Fortovase)], midazolam (Versed) and triazolam(Halcion). Increased drug concentrations usually increase the incidence of side effects.

    Fish Flex: Cephalexin Monohydrate 250mg 



    Keflex, Biocef


    Suspension: 125 mg/5mL 
    Capsules: 250 mg, and 500 mg (cephalexin monohydrate)


    A first generation cephalosporin, cephalexin is a broad-spectrum, bactericidal antibiotic.

    The drug is well absorbed orally, and widely distributed throughout the body. It crosses both placental and fetal serum, and is not recommended during pregnancy. It does not enter cerebral spinal fluid in appreciable levels. It also does not show significant levels in breast milk, and may be given to lactating females.

    It is effective against most Gram-positive organisms such as beta-hemalytic streptococci, Staphylococcus intermedius and aureus, Proteus mirabili, some E. coli, klebsiella, actinobacillis, pasturella, and salmonella. It, however, does not directly attack mycoplasma, but is useful in secondary infections.

    The drug is excreted by the kidneys via tubular and or glomerulo secretion.


    Used for treating deep skin (pyodermas), soft tissue, and urinary tract infections. Also good for use prophylactically following surgery to prevent infection.

    Drug Interactions or Contraindications

    Should not be used orally in cases of septicemia or shock as absorption may be delayed significantly in grave illness.

    Use cautiously with aminoglycosides. May have synergistic effect against certain bacteria, when used with the aminoglycosides, penicillins, and chloramphenicol. Not recommended for concurrent use with bacteriostatics.

    Adverse Reactions

    Blood:  neutopenia, hemolytic anemia

    GI:  anorexia(poor or no appetite), diarrhea, anal pruritus(itching)

    Other:  potential for nephrotoxicity minimal in animals.

    Dosage Recommendations

    60 mg/kg PO   7


    60 mg/kg , PO , q12hrs, or 15 mg/kg , SQ, q12hrs   8


    15 mg/kg , SQ, q12hrs   31


    • Can be used simultaneously with Gentocin.
    • Give yogurt, Lactobacillus capsules/granules, or Bene-Bac to help maintain normal gut flora.
    • May store tablets and capsules at room temperature.
    • Reconstituted suspensions kept refrigerated are good for 14 days.
    • Considered safe for long term use.
    • In treating suspected polymicrobial infections, where a broader coverage may be needed, synergistic or combination drugs may be used. The following drugs may be seen used simultaneously with cephalexin: aminoglycosides (e.g., amikacin or gentamicin), or clindamycin, or fluoroquinolones (e.g., enrofloxacin or orbifloxicin), or metronidazole, or ampicillin . 1
    • Please note that it is imperative to discuss the changing or adding of any medications during your rat’s treatment with your veterinarian to prevent future resistance of microbes to the drugs prescribed.