Feline Infectious Peritonitis
Feline infectious peritonitis
is generally believed to be an incurable condition. Most reported
"recoveries" were probably curable conditions wrongly
diagnosed as FIP. However, treatment can occasionally effect a remission,
sometimes for months.
Note: this section is intended
for veterinary surgeons.
Because FIP is an immune
mediated disease, therapy includes suppressing the immune response,
usually with corticosteroids. Anti-viral treatments alone don't
usually prolong the cat's life by much and many are quite toxic
to cats. It is also important to maintain the cat's general nutrition
status, by adding vitamins and antioxidants. Before embarking on
any of the following therapies, it is essential to ensure that the
diagnosis is correct, immunosuppressive drugs could markedly worsen
other conditions (such as bacterial peritonitis or pleurisy). See
Diagnosis of FIP
I should very much like to
conduct a clinical trial on the effectiveness of various treatments
for FIP, but unfortunately don't have the funding to do so. I'd
like to thank Mr Wayne Carr, whose generous donation made some preliminary
Cats receiving immunosuppressants
should also receive antibiotic cover to protect them against other
is the main immunosuppressant used in feline infectious peritonitis,
it is safe, tends to make the cat feel better and stimulates his
or her appetite. I treated one cat with dry FIP with prednisolone
alone and he survived for 10 months. Prednisolone suppresses both
the humoral and cell-mediated immune response.
Prednisolone has the advantage
of also being the treatment for lymphocytic cholangitis, which can
be mistaken for FIP, so where the diagnosis is in doubt, prednisolone
can be given anyway: the cat with lymphocytic cholangitis has a
good chance of recovery, the cat with FIP unfortunately will die.
Prednisolone should never
be used in cats with septic peritonitis or pleurisy, which is why
cytology is a very important part of FIP diagnosis, as there will
be many more white blood cells in the effusion of a cat with sepsis,
and a good cytologist will detect the bacteria or fungi.
Dose: 2-4mg/kg/day given
by mouth, sliding dose every 10-14 days, until optimal dose for
that cat is found.
rationale of using thalidomide in the treatment of feline infectious
peritonitis is to reduce inflammation and the humoral immune response
to feline coronavirus while leaving the cell mediated (anti-viral)
immune response intact. Only 4 cats with FIP have been treated with
thalidomide so far and unfortunately all died. However, one with
a thoracic effusion did eliminate his effusion and had a remission
of 3 months. I think that, to be effective, thalidomide would need
to be used very early in the disease, before too many blood vessels
Be sure to obtain the owner's
consent for using a drug not licenced for cats.
Dose: 50-100mg at night.
CANNOT BE USED IN PREGNANT CATS as it is teratogenic.
Virbagen Omega - https://www.virbagenomega.com/centre.html
(made by Virbac) is recombinant
feline interferon omega (IFN omega) is available in many countries
now. This product was first used in treatment of FIP by Japanese
vet and scientist Takuo Ishida. He presented his data at SIFFS and
his abstract https://www.felinecoronavirus.com/abstracts.htm#ishida
can be read on the SIFFS website.
This is his protocol:
IFN omega was initially given subcutaneously
at 1 MU/kg every other day, and then once every week for variable
period if remission was seen.
(dexamethasone 1 mg/kg intrathoracic or intraperitoneal injection
once only) or prednisolone. Oral prednisolone was initially given
at 2 mg/kg once daily, and the dosage was gradually tapered to 0.5
mg/kg every other day after remission.
In Dr Ishida's study,
4 cats of 12 completely recovered and two survived 4 and 5 months.
Those cats which recovered completely all had the effusive form
of FIP and were relatively older cats.
Omega does seem to effect a cure in around a third of cats with
FIP. I am working alongside vets in practice in the UK to monitor
a number of cats being treated with this product. It seems to be
very important to begin treatment as soon as possible after the
onset of clinical signs. We are seeing success in younger cats too,
and even cats with non-effusive FIP. Some cats are being treated
orally using 50,000 Units a day. Once diluted (in water or saline)
IFN Omega maintains its potency in the fridge for up to 3 weeks,
so keep most IFN Omega in the freezer until needed.
Virbagen Omega comes in vials of 5 or 10 million units.
It is reconstituted with 1ml of diluent. To get 50,000 Units/ml,
put one 5MU vial into 99mls saline or sterile water, or a 10MU vial
into 198 mls saline or water. Aliquot into 20ml syringes or tubes
and freeze. Remember that reconstituted, diluted Virbagen Omega
lasts only up to 3 weeks in the fridge.
on treatment will appear in the English version of the website before
the translated pages.
Virbagen Omega in UK: Callum Blair (email@example.com)
Omega can be obtained from Abbeyvet (www.abbeyvet-export.co.uk)
et al, 2004. Journal of Feline Medicine and Surgery. Vol 6 Issue
2 pp 107-110
Non-effusive feline infectious peritonitis (FIP): 30 i.u./daily
or for 7 days at alternate weeks given by mouth.
In effusive FIP 30 i.u./daily
can be used, or larger doses of interferon can be given by intramuscular
injection daily (104 - 106 i.u. per day). By 6-7 weeks, if the cat
is still alive, interferon will no longer work at this dose because
the cat will make antibodies against it.
To obtain human interferon-alpha
(Roferon or Intron A), write a prescription for your local pharmacist.
Obviously, in areas where feline interferon is available it is preferable
as it is likely to have more effect than the human interferon.
Diluting human interferon
get 30 i.u./ml: Intron A can be obtained as 1 million i.u. for about
£10.00. Dilute whole vial in one litre of saline, giving 3000
i.u./ml. Put one ml of 3000 i.u./ml into 99ml of saline, to get
30 i.u. per millilitre. Aliquot into 1ml volumes* and freeze for
up to a year. Defrost as required, keep refrigerated for up to a
*In the UK: 2ml tubes are
available from Sarstedt, supplier's ref: 72.694.006. Fax: 0116 236
66099 Tel: 0116 235 9023.
To get 104 i.u./ml put 1
x 1 million i.u. vial of Intron A or Roferon into 99ml sterile saline
and divide into 1ml doses and freeze. For 105 i.u./ml use 9mls saline
and proceed as above. For 106 i.u./ml use the whole vial.
Vitamins and antioxidants
Vitamin A is an antioxidant.
The dose of Vitamin A is 200 i.u./day given by mouth or in the food.
Cats cannot metabolise the beta-carotene form so must be given vitamin
A as fish oil, e.g. halibut liver oil. Too much vitamin A can cause
excessive laying down of bone at the joints, so don't use this supplement
for more than 4-6 weeks.
Vitamin B1 (thiamine)
Vitamin B1 (thiamine): 100 ug/day
given orally (i.e. by mouth or in food).
Vitamin B complex
Multivitamins B are a good
appetite stimulant and can be obtained from health food shops or
chemists (I particularly like the one from Boots). Dose: paediatric
Ascorbic acid 125 mg twice daily
given by mouth or in food. Vitamin C is an antioxidant. Remember
that given over a long period of time, vitamin C can predispose
to oxalate crystals in the urine.
Dose of vitamin E: 25-75
i.u./cat twice dailty given by mouth or in food. Vitamin E is an
Other supportive drugs
For anti-inflammatory activity
and pain relief.
Dose: 10mg/kg every 48-72
hrs per os.
Antibiotic cover is essential
when immunosuppressing a cat.
Dose: 50 mg bid per os.
For appetite encouragement and
anti-catabolism, especially if the kidneys are affected.
Choose from the following
(in the UK):
Laurabolin injection: 2-5mg/kg every 21 days.
Nandrolin injection: 2-5mg/kg as a weekly injection.
tablets - one a day either whole or crushed into food.
injection: 1mg/kg every 21 days.
Orandrone tablets: 0.5mg/kg
daily (the tablets are 5mg).
Remember to warn the owner
that the cat's urine could become more strong smelling with this
The injectables usually require to be kept in the
Two cats with abdominal effusions
were treated with ozagrel hydrochloride with success (Watari et al, 1998).
Dose: 5-10mg/kg twice daily
and prednisolone at 2mg/kg/day.
Monitoring treatment /
Whatever treatment you opt for, it is important to monitor
the cat's progress. Initially, I measure the haematocrit (Hct),
globulins, albumin to globulin ratio (A:G), alpha1-acid glycoprotein
(AGP) and the cat's weight every 7-14 days to see how the cat is
examinations might only be monthly if the cat is doing well. It
is not worth measuring the FCoV antibody titre more often than every
2-3 months, there will be no discernible difference within a shorter
period. The AGP should be the first to fall if treatment is having
a positive effect because AGP is a measure of inflammation. Positive
signs are globulin levels decreasing, and the albumin: globulin
ratio(A:G) increasing, Hct increasing and reticulocytes appearing
in blood smears and weight increasing. Negative signs are AGP remaining
high, globulins staying high or increasing, A:G decreasing, weight
loss. When Hct gets to below 20% and is non-regenerative (no reticulocytes
seen on blood smear examination) then the cat should probably be
humanely euthanased if your clinical opinion is that he or she is
no longer getting any happiness out of life. Clearly, if the cat
is distressed at any point in the treatment, then euthanasia will
be required. Sadly, cats with effusive feline infectious peritonitis
usually only survive a few days, possibly weeks at best. Cats with
non-effusive FIP can last many weeks or months, though after neurological
signs begin euthanasia usually ensues fairly rapidly.
For AGP testing see Companion Animal Diagnostics. (https://www.gla.ac.uk/companion)
Feline Infectious Peritonitis Virus:
Advances in Therapy and Control by Richard C. Weiss. 1994 Consultations
in Feline Internal Medicine 2. Edited by John R. August. Published
by W.B. Saunders Company. Harcourt Brace Jovanovich, Inc., The Curtis
Center, Independence Square West, Philadelphia, PA 19106. pages
Ishida T, Shibanai A, Tanaka
S, Uchida K, Mochizuki M. 2004 Use of recombinant feline interferon
and glucocorticoid in the treatment of feline infectious peritonitis.
Watari T, Kaneshima T, Tsujimoto
H, Ono K, Hasegawa A. 1998 Effect of thromboxane synthetase inhibitor
on feline infectious peritonitis in cats. J Vet Med Sci. 60(5):657-9.
Dr Diane D. Addie 17 March 2006
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