Page 286 - Small Animal Internal Medicine, 6th Edition

258 PART II Respiratory System Disorders

individual cats with acute disease because most cats recover with known concurrent disease and for cats expected to
uneventfully. It may be of value to test individual cats with receive famcyclovir for long periods. They also state that
VetBooks.ir severe or persistent signs because specific antimicrobial twice-daily dosing at 90 mg/kg is likely to be sufficient, based
on pharmacokinetic studies.
treatment for FHV, Chlamydia, or Mycoplasma can be pre-
It has been postulated that excessive concentrations of
scribed. False-negative results may occur if signs are the
result of permanent nasal damage or if the specimen does L-lysine may antagonize arginine, a promoter of herpesvirus
not contain the agent, and positive results may merely reflect replication. Lysine (500 mg/cat q12h), obtained from health
a carrier cat that has a concurrent disease process causing food stores, is often added to food for the treatment or pre-
the clinical signs. vention of FHV. Its effectiveness is not certain (Thomasy and
Maggs, 2016).
Treatment Chlamydophila infection should be suspected in cats with
In most cats URI is a self-limiting disease, and treatment of conjunctivitis as the primary problem and in cats from cat-
cats with acute signs includes appropriate supportive care. teries in which the disease is endemic. Oral antibiotics are
Fluid therapy and nutritional supplementation should be administered for a minimum of 42 days. In addition, chlor-
provided when necessary. Dried mucus and exudate should amphenicol or tetracycline ophthalmic ointment should be
be cleaned from the face and nares. The cat can be placed in applied at least three times daily and continued for a
a steamy bathroom or a small room with a vaporizer for 15 minimum of 14 days after signs have resolved.
to 20 minutes two or three times daily to help clear excess Corneal ulcers resulting from FHV are treated with
secretions. Severe nasal congestion is treated with pediatric topical antiviral drugs, such as trifluridine, idoxuridine, or
topical decongestants such as 0.25% phenylephrine or adenine arabinoside. One drop should be applied to each
0.025% oxymetazoline. A drop is gently placed in each affected eye five to six times daily for no longer than 2 to 3
nostril daily for a maximum of 3 days. If longer therapy is weeks. Routine ulcer management is also indicated. Tetracy-
necessary, the decongestant is withheld for 3 days before cline or chloramphenicol ophthalmic ointment is adminis-
another 3-day course is begun to prevent possible rebound tered two to four times daily. Topical atropine is used for
congestion after withdrawal of the drug (based on problems mydriasis as needed to control pain. Treatment is continued
with rebound congestion that occurs in people). for 1 to 2 weeks after epithelialization has occurred.
The Antimicrobial Guidelines Working Group of the Topical and systemic corticosteroids are contraindicated
International Society for Companion Animal Infectious Dis- in cats with acute URI or ocular manifestations of FHV
eases recommends that antibiotic treatment be considered infection. They can prolong clinical signs and increase viral
during the first 10 days of clinical signs only if fever, lethargy, shedding.
or anorexia is present concurrently with mucopurulent nasal Treatment of cats with chronic signs is discussed later
discharge (Lappin et al., 2017). This group recommends with feline chronic rhinosinusitis.
doxycycline (5 mg/kg, PO, q12h; or 10 mg/kg, PO, q24h;
always followed by a bolus of water or food) as the first-line Prevention in the Individual Pet Cat
option because of its efficacy against Chlamydia and Myco- Prevention of URI in all cats is based on avoiding exposure
plasma. Amoxicillin (22 mg/kg, PO, q8-12h given orally) is to the infectious agents (e.g., FHV, FCV, Bordetella, Myco-
considered an acceptable alternative when those organisms plasma, and Chlamydophila organisms) and strengthening
are not highly suspected. Doxycycline should be adminis- immunity against infection. Most household cats are rela-
tered for 42 days in cats infected with Chlamydophila felis or tively resistant to prolonged problems associated with URIs,
Mycoplasma spp. to eliminate detectable organisms (Hart- and routine health care with regular vaccination using a
mann et al., 2008). Azithromycin (5-10 mg/kg q12h for 1 subcutaneous product is adequate. Vaccination decreases the
day, then every 3 days, orally) can be prescribed for cats that severity of clinical signs resulting from URIs but does not
are difficult to medicate. prevent infection. Owners should be discouraged from
Cats with FHV infection may benefit from treatment with allowing their cats to roam freely outdoors.
famcylovir. Several clinical trials have shown therapeutic Subcutaneous modified-live virus vaccines for FHV and
benefit. In a placebo-controlled trial, 26 cats receiving a FCV are used for most cats and are available in combination
dosage of 90 mg/kg three times daily had significantly with panleukopenia vaccine. These vaccines are convenient
reduced clinical signs (Thomasy et al., 2016). In these cats, to administer, do not result in clinical signs when used cor-
the time to clinical improvement was 3 to 28 days (median, rectly, and provide adequate protection for cats that are not
7 days). Side effects occurred in 15% of cats receiving this heavily exposed to these viruses. These vaccines are not
dosage and were primarily gastrointestinal, including diar- effective in kittens while maternal immunity persists. Kittens
rhea, vomiting, anorexia, and weight loss. Experience with a are usually vaccinated beginning at 6 to 10 weeks of age and
larger number of cats and chronic administration of drug is again in 3 to 4 weeks. At least two vaccines must be given
needed to fully understand the potential risks of treatment initially, with the final vaccine administered after the kitten
with this drug. Thomasy and Maggs (2016) recommend that is 16 weeks old. A booster vaccination is recommended 1
cats should be closely monitored, and that CBC, serum bio- year after the final vaccine in the initial series. Subsequent
chemistry panel, and urinalysis be considered for those cats booster vaccinations are recommended every 3 years, unless