About FIP

FIP is caused by a mutation of FECV. Although the mutation of FECV to FIPV is common, it is fortunate that only a small percentage of cats exposed to this mutant virus will get FIP. FECV is undergoing continuous mutation and several genetic forms of the virus may co-exist in the same animal at the same time. Most of these mutations have very little effect on the behavior of the virus and merely serve to genetically reflect the region from which the virus originated. However, certain have a pronounced effect on the biologic behavior of the virus One study indicated that 20% of the kittens infected with FECV will produce an FIP mutant. Of course, only a fraction of the mutants will go on to produce FIP, depending on host resistance factors (genetic or non-genetic).

This FECV to FIPV genetic change is referred to as the internal mutation theory. The internal mutation theory has two corollaries: 1) that each cat that develops FIP, even if it is a littermate, closely related or commonly housed, has a unique mutation, and 2) that horizontal (cat-to-cat) transmission of the FIPV mutant is uncommon. Researchers at UC Davis have reconfirmed corollary 1, and have confirmed corollary 2 in concept but not in fact. Reconfirmation for the internal mutation theory came from a recent outbreak in three kittens in a litter of Scottish Folds and in a half-sibling from a second litter. All four FIPVs had very similar yet genetically unique gene mutations. These mutations were not present in a fecal form of the virus that was being shed by a healthy contact cat.

Cats who develop clinical cases of FIP may initially show nonspecific symptoms such as growth retardation, loss of appetite, depression, rough coat, weight loss, a fluctuating antibiotic resistant fever, and increased susceptibility to secondary infections (such as respiratory disease). More specific signs of FIP vary depending on the form of the disease (wet vs. dry) and the organs that are involved.

The most common form of the disease is referred to as “wet FIP.” Wet FIP is caused by inflammation of the linings of the abdominal viscera, and less commonly of the thoracic organs. This inflammation exudes large volumes of a characteristic mucinous, yellow-tinged fluid (exudate). Therefore, the major clinical sign in the wet form of FIP is ascites and abdominal distension (abdominal involvement) or dypnea (thoracic involvement).

FIP can also take a more chronic form referred to as “dry FIP”. Dry FIP, as the name implies, is not associated with fluid accumulations in the abdomen or chest, but rather with more localized masses in the kidneys, spleen, liver and terminal bowel, eyes, and the linings of the lungs and heart, and central nervous system. Uveitis (intraocular inflammation) can affect the eyes, making them look cloudy and changing the colour of the iris. Inflammation can enter the brain and spinal chord and cause a spectrum of progressive neurologic abnormalities. FIP accounts for over one-half the cases of inflammatory intraocular and nervous system disease in cats under 3-5 years of age.

Cats with FIP do not appear to be very contagious to cats that they come in contact with. Although this has been based mainly on clinical observations, it has also been confirmed by laboratory studies. Contact transmission has not been observed in experimental settings. Furthermore, cat-to-cat transmission implies that every FIPV isolated from a group outbreak of FIP will be genetically identical. UC Davis researchers have yet to observe this. However, researchers now know that FIPV is present in the feces of some cats with FIP, so horizontal transmission is theoretically possible, and may explain the uncommon epizootics of FIP where a number of cats in the same environment develop FIP within a days or weeks of each other.

There is no single definitive test for FIP at this time, however the diagnosis of FIP should be relatively simple given its affinity for younger cats, its strong tendency to involve catteries and shelters, the typical physical and historical findings, and numerous characteristic laboratory abnormalities. Nonetheless, it remains one of the most difficult of diagnoses for many veterinarians. The truth is that veterinarians have little trouble in placing FIP high, or at the top, of their diagnostic list, but have great difficulty, and even reluctance, in confirming their diagnosis. This is probably because FIP is viewed as a death sentence, and they are reluctant to confer such a sentence without certain proof.

Although a definitive test result would assist decision making, a certain diagnosis can be based on cumulative odds rather than a single, simple, definitive test result. A young cat from a cattery or shelter with chronic uveitis and/or neurologic signs, high serum proteins, hyperglobulinemia and hypoalbuminemia, fluctuating antibiotic unresponsive fever, leukocytosis with a lymphopenia, and an anemia of chronic disease can have no other disease than dry FIP based on odds alone. Likewise, the same cat with similar history and laboratory findings, but with yellow-tinged, mucinous, inflammatory ascites is highly unlikely to have any other disease than wet FIP.

1. 1. I have been told that if the kitty misses 1-day dosage the next dosage has to be doubled to cover the previous dosage?
      No. Missing one dosage is not serious, because effective blood levels are sustained over 24 h. However, missing a dose is something that should be avoided if all possible as it can become a habit.
   2. Must the GS Dosage be administered exactly 24 hours day to day? What if work gets in the way and I am late for the next dosage by 3 to 4 hours or in another scenario what if my vet is closing early dur to unforeseen reasons can I give the jab earlier? If I do what will the best time be for the next jab for the following day.

No, for the same reason given in question #1. There is flexibility in dosing, but again, continually varying the time of administration to meet owner’s schedules does not speak well for the commitment of the owner to the treatment and their cat.

3. 3. I have heard that using flea prevention medication such as advocate, revolution, frontline can affect GS effectiveness. If Yes, can kitties use Seresto collar even if its active ingrediencies is absorbed into the fatty layer of the skin.

There is no scientific evidence that any available flea treatment has a negative effect on GS-441524 treatment. However, I am personally against the use of systemic insecticides to control fleas on a cat. They work on the fact that the insecticide is less toxic for the cat than for the fleas that feed on it. Their sole use for flea control is an admission of defeat that is akin to the military tactic of calling in the artillery on your position when it is being overrun by the enemy.

4. 4. I was told that if your GS medication is running out, and you are still waiting for shipment of the new vail. You can reduce the dosage by half for that day rather than having use all and skipping a day or two

Yes, this can be done as the best alternative to giving no treatment. It may be better, based on the half-life to GS in the bloodstream, to give a full dose every other day rather than a half dose every day. However, like skipping doses when drug is available and greatly altering the daily injection time, it is something that should not become a routine practice.

5. 5. Is completing 12 weeks (83 days) recommended or is it a must? I’ve been told that if kitty A/G ratio goes back to 0.7 even if you are only 3 to 4 weeks in you can actually stop and monitor if there is a relapse

It would be a great discovery to have a simple test that could accurately determine when a cure has occurred, but in its absence, we can only go by significant and progressive improvement in signs of outward health (activity, alertness, appetite, weight gain, quality of coat) and all of the most relevant blood test values (hematocrit, white blood cell count, lymphocyte count, total protein, albumin, globulin and A:G ratio). The 12-week treatment period is based on field trials with both GC376 and GS-441424 and is a period that allows for the maximum proportion of cures. There is no doubt that some cats are not cured even over 12 weeks and some evidence that some can be cured sooner (i.e, 8- 10 weeks). However, early cessation of treatment will always lead to a decrease in the proportion of cats that are cured, and the sooner you stop a treatment, the higher the relapse rate. In the end, it is up to the owner and their veterinarian to make the decision when to stop treatment and began the post-treatment observation period.

6. 6. Is there any harm to keep giving GS even if the A/G ratio has gone back to normal before the 12 weeks are completed

No, there is no harm in treating longer than usual, but treatment is expensive and hard on both cat and owner. That is why I have given definite instructions on when and how to extend treatment.

7. 7. I’ve been told that its best to increase the dosage from 8mg to 10mg if the bloodwork shows no improvement on the A/G ratio for the first 4 weeks

It is common to divide a treatment into 4-week blocks, ending with new blood tests. The rule is not to increase the dosage unless it is strongly indicated by outward response to treatment (see question #5) and blood test results. If there is good reason to increase the dosage, it should be for at least +2 to +5 mg/kg daily and for a minimum of 4 weeks. Of course, dramatic changes in the form of FIP, e.g. ocular or neurological, require immediate changes in dosage.

8. 8. I’ve heard that deworming medication cannot be used during GS treatment period

There is no evidence that any deworming medications have a negative effect on GS treatment. Like any extra medication added to the mix, there should be strong reasons to use it (i.e., benefits outweigh risks).

-Niels C. Pedersen, DVM, PhD, School of Veterinary Medicine, UC Davis.

This is from the leading doctor working on FIP

Niels C. Pedersen, DVM, PhD, School of Veterinary Medicine, UC Davis.