by John Bennett
Anyone working in cat rescue has had some exposure to the calici virus. The calici virus is one of the feline infectious organisms that collectively are known as upper respiratory infection. Research shows that 80–90% of upper respiratory infections are caused by either the calici virus, the herpes virus, or a combination of the two. Typical calici virus symptoms are oral ulcers, eye and nose discharge, and joint and muscle pain. Appetite is typically not affected unless there is difficulty eating or chewing food due to oral ulcers.
This is what we had all come to expect from this virus -- until now. A variant of the virus, termed "hot calici," has recently passed through the Folsom area, infecting a number of cats and kittens. Most of the adults were infected with the known variety, with normal symptoms. However, the infected kittens were a different story. As the photos show, we saw new symptoms including swollen ears (Figure 1) plus hair loss around nose (Figure 2), ears, and paws. Some of the standard calici-like symptoms were also seen, such as muscle soreness and eye discharge, but very little respiratory signs were noted. Some of the kittens also tested positive for mycoplasma, a bacteria that is resistant to standard antibiotic treatment. In severe cases, the ears of infected kittens can be so swollen and weighted that the ears literally flop over, as shown in Figure 3. Severe drooling may also be seen, and lasts for a few days before clearing up.
Figure 1. Mild to extreme ear infections.
Figure 2. Hair loss around nose.
Figure 3. Extreme ear infection.
Folsom Feline Rescue worked with Blue Ravine Animal Hospital to diagnose and discover a treatment for this virus. PCR swabs of the larynx were used to determine the cause of the infection for the initial group of infected kittens. Treatment began with antibiotics such as Clavamox to help prevent secondary bacterial infection and allow the cat's own immune system to counteract the virus. However, this treatment alone was not effective. Further treatment with Tamiflu, doxycycline, and Interferon was also tried. Doxycycline and Clavamox appeared to be the best treatment for infection. Interferon appeared to help with the healing of oral ulcers in adult cats. Some of the severely-infected kittens needed fluids and regular force-feeding to maintain hydration and weight. 70–80% of the kittens survived the infection as long as the virus did not attack the organs or cause additional complications such as pneumonia.
Cats vaccinated with a standard 3-in-1 (panleukopenia, calicivirus, and rhinotracheitis) or 4-in-1 (includes chlamydia) series seemed to hold off any infections. (However, newly-vaccinated cats may still be infected by the virus or show mild symptoms such as muscle soreness or limping for a few days.) Kittens needed a number of vaccinations before enough immunity was gained to fight off the virus. Kittens building immunity, or with an existing weak immune system, showed signs of muscle soreness, some hair loss on the nose, or smaller sores on an ear when infected. These kittens also recovered quickly and had no loss of appetite. The incubation period was very fast -- in the 1- to 10-day timeframe, with duration of the illness in the 1- to 2-week timeframe. Newly-acquired kittens vaccinated on arrival still became infected within 3 days to a week's time.
This virus is highly infectious -- more so than anything we have experienced in the past. It is also not as susceptible to standard cleaners and we were not able to determine the effectiveness of Nolvasan as a disinfectant. A 1:32 dilution of household bleach is the recommended disinfectant. The virus also has a short environmental longevity of 8 to 10 days.
Once we realized the severe nature of this infection, we isolated any cat or kitten showing any symptoms and used hand disinfectant religiously while following isolation practices. All cat intakes were put on hold as much as possible, and all cats or kittens were vaccinated immediately upon their arrival. Within three weeks we had this outbreak under control, with the last infected kittens in recovery. If it was not during the height of "kitten season," the impact of this outbreak would not have been so damaging. I hope this article can help those who may come across this calici variant and speed your kittens along the path to recovery.
Resources
Arnold Plotnick MS, DVM, ACVIM, ABVP
Manhattan Cat Specialists, manhattancats.com
Feline Upper Respiratory Disease Complex
Holly Nash, DVM, MS Veterinary Services Department, Drs. Foster & Smith, Inc. 