Valley Fever Center for Excellence

Coccidioidomycosis

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Treatment of Valley Fever in Dogs

In most cases, a dog ill enough from Valley Fever to be seen by a veterinarian will require treatment with antifungal medication. Courses of medication are usually extensive, averaging 6-12 months. Dogs with disseminated disease in bones, skin, or internal organs usually require longer courses of medication. Central nervous system (brain or spinal cord) involvement frequently requires lifetime treatment with medication to keep symptoms from recurring.

Oral antifungal medication in the form of twice daily pills or capsules is the usual treatment for Valley Fever. There are three common medications used to treat Valley Fever in dogs.

  • Ketoconazole (Nizoral)
  • Itraconazole (Sporanox)
  • Fluconazole (Diflucan)

These medications all target the same pathway in the fungus to inhibit its growth in the dog, but they differ in some of their chemical properties and in their metabolism. Some side effects are common to all three drugs:

  • stomach and intestinal upset - lack of appetite, nausea, vomiting, and diarrhea
    • elevations in liver enzymes - ketoconazole and itraconazole are extensively metabolized by the liver and 10-20% of fluconazole is metabolized by the liver. An individual dog may have a bad liver reaction even to fluconazole
    • birth defects in fetuses. These medications should only be used in pregnant dogs when the benefits to the mother outweigh the risk to the developing puppies

Fluconazole

Currently (2014), this is the most widely prescribed oral Valley Fever medication in use by veterinarians in southern Arizona. Its advantages include

  • excellent absorption from the GI tract, even in dogs that are not eating
  • generally easier on the liver
  • will cross into the brain and eye tissues - drug of choice for infection in these sites
  • available as a generic drug at significant cost savings over Diflucan

Drawbacks:

  • this drug is cleared by the kidney and dose may need to be reduced in animals with compromised kidneys
  • may cause thinning or dryness of the coat with dandruff. Dandruff seems most noticeable or most common in black dogs. Effects are reversed when drug is withdrawn
  • occasional reports of excessive drinking and urination
  • In 2013, the drug underwent a 5-fold increase in price due to reduction in manufacturers of the generic drug

Ketoconazole

Ketoconazole was the first oral Valley Fever drug available and is still in use, almost exclusively as a generic drug. Some of its important characteristics are

  • requires an acidic environment for absorption from the GI tract. It is often administered with Vitamin C to aid in absorption
  • has a higher incidence of stomach and intestinal upset than fluconazole
  • is a good Valley Fever drug in cases where it is making the dog well
  • causes a usually reversible lightening of the coat color, particularly prominent in red and gold dogs. Most dogs return to a normal color after the medication is stopped
  • makes male dogs infertile while they are taking the medicine. This is also reversible when the medication is stopped

Itraconazole

In laboratory studies, itraconazole is a more potent drug against Valley Fever than fluconazole but has some drawbacks compared to fluconazole in the clinical setting. These include

  • possibly higher incidence of stomach and intestinal upset
  • more likely to increase liver enzymes; metabolized by the liver
  • development of drug-related skin reactions that can range from mild ulcerations to severe abscesses or sloughing of hair and extensive dermatitis. This appears to be partially dose dependent and lower doses are less likely to result in this reaction
  • less absorbable from the GI tract than fluconazole. Medication must be administered with a meal in the capsule form

Advantages:

  • often effective in cases not getting well on fluconazole
  • can be administered once daily instead of twice daily to some patients, which may be easier on owners and pets

Itraconazole is available as a US generic capsule that is approximately equivalent to Sporanox in its ability to be absorbed from the intestine. The capsular form of this drug is specially formulated on dextran beads to aid in solubility, and hence absorption. Make sure your itraconazole capsules have little beads inside them and not a powder. Itraconazole capsules should be administered with food.

Sporanox also comes in a liquid formulation. This is not available in a generic form at the time of this writing. Liquid Sporanox may be a good choice for cats or for small dogs. Unlike the capsules, liquid Sporanox is formulated to be better absorbed on an empty stomach.

Amphotericin B

Amphotericin B is an old but very effective antifungal medication that is mainly used for extremely sick dogs in today's veterinary practices. This drug must be administered intravenously in the hospital and has the serious drawback of toxicity to the kidneys. Newer lipid-based formulations of amphotericin B (brand names: Abelcet, Ambisome) have a much lower likelihood of damaging the kidneys and are mainly used in dogs that are either very ill with Valley Fever or are not recovering on oral medication.

Other Drugs

Drugs more recently introduced to the market for treatment of fungal disease in humans include:

  • Voriconazole (Vfend)
  • Caspofungin (Cancidas)
  • Posaconazole (Noxafil)

The role of these drugs in treating human Valley Fever is not yet clear. Voriconazole has absorption and treatment characteristics similar to fluconazole, but is more potent in laboratory studies. Caspofungin targets a different pathway in the fungus than the other drugs available; it must be administered intravenously in the hospital. Posaconazole shows promise for the treatment of severe fungal infections in animals in the few publications found, but it cannot be detected in central nervous system tissues and may not be a good choice for brain disease. The use of these newer - and hence more expensive - medications will likely find their way into treatment of dogs with very bad cases of Valley Fever.

Terbinafine, added to one of the common Valley Fever medications, may improve the response to treatment for dogs that are not getting well on their medication. There are no actual studies of this drug in dogs, but in the laboratory it can kill Valley Fever fungus growing in culture, and dogs are able to absorb the drug with good blood levels. Observations suggest about half of dogs that are responding inadequately to a single drug will improve with the addition of terbinafine. Side effects are low but could include increases in liver enzymes and intestinal upset.

Supportive Treatments for Sick Dogs

Other treatments for Valley Fever are mainly directed at supportive care: making your dog feel better while the antifungal medication starts to heal the infection.

  • Cough suppressants - your veterinarian may prescribe medicine to relieve coughing, especially if it is one of the major symptoms
  • Pain and fever relief - anti-inflammatories or pain medication prescribed by your veterinarian may greatly help your dog's attitude and appetite during the severe stages of the disease
  • Nutritional support - while some dogs eat reasonably well with Valley Fever, others shun food entirely. These patients need extra nutritional care, such as hand-feeding highly palatable food (e.g. cooked meats), placement of a feeding tube, medication to reduce nausea and vomiting or stimulate appetite
  • Hospitalization - dogs that are too sick to eat and drink and are becoming dehydrated or are in severe respiratory distress may need 24-hour care, intravenous fluids, oxygen, or other medication that can only be given in the hospital environment.

FAQ – What is the best treatment for Valley Fever?

Treatment choices vary by the individual veterinarian and patient. Reasons for choice of medication include practitioner's experience with the drugs, costs, side effects, efficacy, severity of illness, and convenience to the owner. If one medication is unsuccessful, another will often be tried.

For disease of the brain and spinal cord, fluconazole (Diflucan) is the drug of choice. Fluconazole also penetrates tissues of the eye and should be employed in ocular cases.

FAQ – What is the proper dose of Valley Fever medications?

Your veterinarian is skilled in the diagnosis and treatment of your pet's illness. Should you feel that your dog is not responding or may have side effects to the medicine, you should first discuss your concerns with your veterinarian. If the results are not satisfactory, you can seek a second opinion.

FAQ – What are the side effects of oral Valley Fever drugs (ketoconazole, itraconazole, and fluconazole) in dogs?

All Valley Fever medications have the potential to cause side effects in dogs. The side effects that are common to all of them are:

  • Loss of appetite is the most common and may be severe in some dogs.
  • Vomiting and/or diarrhea.
  • Elevated liver enzymes – monitored with regular testing of your dog’s blood by your veterinarian.

Less common or drug specific side effects include:

  • Lightening of the coat color, especially in red or golden dogs. Effects reverse with discontinuation of the medication (with the exception of a few black dogs this author has heard about that have remained grey). (ketoconazole)
  • Dry, thin coat and dry skin with dandruff. (fluconazole)
  • Excessive drinking and urination, leaking urine in sleep. (fluconazole)
  • Ulcerated or abscess-like lesions of the skin. (itraconazole) A reduction in dose may reduce this side effect, or the dog may have to discontinue the medication.
  • Infertility in males (common with ketoconazole; possible with fluconazole; unknown with itraconazole). Reversible when drug is withdrawn.
  • Birth defects in fetuses. Published side effect of all drugs in this class. Should be used when benefits to mother outweigh risks to babies.

FAQ – What happened to the price of generic fluconazole and what can I do about it?

In 2013, most of the manufacturers of generic fluconazole stopped making it. There is only one manufacturer left, which has driven the price up 5- to 10-fold. While this has created a hardship for dog owners, especially of larger dogs, there is essentially nothing that can be done about the cost of the drug. It is recommended that owners call different pharmacies to check for the best pricing of fluconazole.

Fluconazole can also be compounded, which generally costs less than generic medication, but compounding also increased in price in 2013. Compounded fluconazole generally works fine, but there may be more prescription-to-prescription variability in the drug than when buying generic. If your dog is not doing well on compounded fluconazole, it is worthwhile to try the generic and see if there is a difference. Online purchase may also be an option, but the research we have done shows little advantage to online pricing for fluconazole, at least for dog owners in Arizona.

FAQ – Are there vitamins, nutritional supplements, or alternative therapies for dogs with Valley Fever?

Most ill dogs could receive a pet multivitamin supplement safely and possibly with benefit to overall well-being. Vitamin C is often prescribed to be administered with ketoconazole. This aids absorption of the drug by helping to acidify the stomach and may also "boost" the dog's immune system. Use of the vitamin C should be checked with your veterinarian as high doses may cause gastrointestinal irritation.

Talk to your veterinarian about your dog's overall nutrition status and the nutritional goals you need to meet while your pet is ill. The more ill your dog, the more important it is to discuss this issue with your vet.

For dogs that will eat nothing at all, force feeding may be an option to attempt to meet the nutritional needs of your pet. For help in determining if this drastic measure should be taken and what food should be used to implement it, talk to your veterinarian. Force feeding is a big commitment of time and can be an unpleasant venture for both dog and owner, but in occasional situations may mean the difference between recovery and loss of the dog. If the dog's nutritional needs can't be met with a hand feeding regimen, surgical placement of a feeding tube is an alternative.

Denamarin, a combination of a milk thistle extract (silymarin) and SAM-e, has antioxidant properties that help the liver cope with the “stress” of the valley fever drugs. If dogs are experiencing mildly elevated liver enzymes, Denamarin, Denosyl, or high quality health food store versions of milk thistle and SAM-e will often result in lowered enzymes at the next blood test. Check with your veterinarian for doses of the supplements. Denamarin and Denosyl are veterinary products adjusted for your dog’s body weight and these are recommended. Check with your veterinarian to buy these products and get advice on using them. If your clinic does not carry them, they are available online, but should be used under the instruction of your veterinarian.

Alternative therapies, such as herbs or acupuncture, have not been scientifically tested to treat Valley Fever. The majority of veterinarians to whom I have spoken use these therapies adjunctively with antifungal drugs to help support the dog's overall health and to improve function of the immune system. If you wish to pursue alternative treatments, this author recommends you consult a veterinarian trained in holistic medicine. These professionals are your best source of help.






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