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RESPIRATORY INFECTIONS IN CATS

DVM, PhD Suvi Pohjola-Stenroos
Cat Clinic Felina
Työmiehenkatu 4 C
00180 HELSINKI, FINLAND
+358-9-686 6560

Feline upper respiratory problems occur very often, especially in cattery cats. They may be caused by viral infections or bacteria or both of them. Besides infectious agents we sometimes can detect that symptoms are caused by inhalant allergens. Here we only talk about infectious agents.

Herpesvirus (rhinotracheitis)

Herpes infection is the most important disease in cattery cats. The virus genome remains in the trigeminal ganglion in the head until an animal is stressed. Then the virus is activated, grows down into the nerve, and reinfects the mucosal cells where it replicates and is shed. Animals that are infected remain latent carriers, that is they will shed the virus whenever they are stressed. The first episode will normally take several weeks, but recurrence lasts 3-10 days.

Clinical signs are ocular or systemic signs. Bilateral keratokonjunktivitis, may see some corneal ulcers, especially in those breeds with large eyes. The eyes are very painful. The cat will have the eyes mostly closed, and massive production of tears can be observed.- Systemic signs include rhinitis, that is inflammation of the nasal mucosa. So the cat will sneeze. First the secretion is watery but later on will appear mucopurulent, because the mucosal lining will ulcerate and secondary bacteria will adhere. Some cats will develop chronic rihinitis/sinuitis due to the permanent turbinate damage of the nasal cavity. Pneumonia (lung infection) in very young kittens may lead to death rapidly.

The diagnosis of herpes virus infection is made by culturing the nasal, ocular or oropharyngeal exudates. Also intranuclear inclusion bodies can sometimes be seen in cell scrapings taken from conjunctiva.

The treatment includes antiviral drugs (ophthalmic solutions on the eyes), systemic antibiotics to prevent secondary bacteria, fluids if necessary and other kind of supportive care in the acute phase. In chronic cases you can keep the nasal passages clear for examples with Neosynephrine (use every other day). Steroids (cortisone) are always contraindicated as they reactivated the infection and suppress the immunity. Steroids also prevent the corneal ulcers to heal.

Prevention is the most important task. Vaccinate your cat properly. Do not use modified live vaccines, because you can bring live virus contamination to your cattery. Especially, if you suspect corneal ulcerative problems, do never use modified live vaccines. In my cattery we vaccinate every kitten three times as they are kittens; first at 8 weeks old, then at 12-weeks and 16 weeks old. After that annually. To provide the good maternal colostral protection vaccinate your queen in the middle of the pregnancy but always use killed vaccines. Maternal antibodies are passed with milk to the kittens but will disappear when the kittens are around 1 month. That is the most susceptible period or their lives. See the comparative picture about modified live and killed vaccines in the last page).

Calicivirus

Victims are kittens in catteries. Calici is very common, about 20 % of cats shed this virus. There are several strains and not necessary vaccines strains are the same that occur in catteries. Calici is shed from the oropharynx into the saliva, some is shed via faeces.

Clinical picture is of transient sickness (2-4 days). Fever, limping, oral vesicles, that range from pinpoint to large. They may be on palate or on tongue, sometimes ulcers also in lips, limbs and nose.

Diagnosis is possible by culturing the virus. Calicivirus infection is best treated with supportive care. Put the cat on a soft food diet, this allows the lesions to heal. Chronic cats should be tested against FeLV and FIV infection. Preventive treatment is best carried out by vaccinating the cats. There are hundreds of strains, and not all strains are covered with the vaccines.

Chlamydia psittaci

Bacteria. Common in cattery cats. It affects primarily kittens around weaning when they have poor maternal immunity left. Kittens are infected by adult cats or older kittens. Transmission occurs with faeces and discharges (eyes and nose). Recovered cats may become carriers and often don't develop good immunity. Recurrent infections may happen, but often they decrease with maturation of the immunity.

Clinical signs are unilateral conjunctivitis, also severe conjunctivitis in the unopened eyes of the new-born kitten is possible. Some young kittens (2-4 weeks) may develop fatal pneumonia leading to death. We don't usually see the respiratory signs at all, we just see the death. Chlamydia also induces reproductive problems and also abortion.

Diagnosis in chlamydial problems is based on examination of conjunctival scrapings, or so called IFA-test, or PCR. Chlamydial infections are best treated with macrolides like azithromycin or tetracyclines or their derivatives, treatment time may be long, and dosing should be continued for 2 weeks after the resolution of the clinical signs. Preventive measures includes good cattery management hygiene. Vaccination can be used in severe cases, but the immunity is not longlasting or solid.

Mycoplasma

Bacteria. Cattery cats are susceptible, recovered animals may become carriers. Mycoplasma is shed in exudates. Signs are mainly ocular: uni- or bilateral conjunctivitis, not very painful, can get concurrent Chlamydial infection. Systemic signs may develop in 3-4 weeks old kittens. Mycoplasma may induce abortion in the queen.

Diagnosis is made by conjunctival scrapings and also by culturing in special agar plates. There is no vaccine available. Treatment is with tetracyclines or their derivatives at least for two weeks. This antibiotic is static for the bacteria, thus cats immunity must kick the bacteria away.

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