Epsilon Archive for Student Projects

Abstract

Salmonella in cats has been documented for many years. Infection with S. Typhimurium,
which is often referred to as Songbird fever, is believed to be caused by birds who
inadvertently infect cats. The disease is often seen during the springtime when songbirds
return from their winter habitats, while other birds who have stayed during the winter are in
their weakest condition of health. In the spring of 1999 an epidemic of S. Typhimurium in
cats was recorded in Karlstad in Sweden and the National Veterinary Institute in Uppsala,
Sweden has in addition documented hundreds of cases of S. Typhimurium in cats over the last
couple of years.

Two studies were performed to look at Salmonella in cats in Sweden. The first study included
56 cats, some were privately owned outdoor cats and some were homeless cats recently
adopted into shelters. Fecal samples were collected in March 2007 in the Stockholm and
Uppsala areas. The laboratory tests showed that one of the 56 cats was positive for
Salmonella. This cat which was staying at an animal shelter excreted S. Typhimurium but it
did not show any symptoms of disease. All of the cats included in the study had been
outdoors for a period of time shortly before being testing.

The second study was done retrospectively. It included all of the samples from cats sent to the
Swedish National Veterinary Institute for Salmonella testing during the year 2006. This study
showed that 46 % (68 of 148) of the samples were positive for Salmonella spp. All of the
positive samples but one were identified as S. Typhimurium. Furthermore one S.
Typhimurium was typed as DT40 and the last Salmonella spp. was identified as being S.
Enteritidis NST.

The time of infection supports the theory that the cats carrying S. Typhimurium were infected
by songbirds. All of the samples that were positive for S. Typhimurium were collected
between January and June 2006. The majority of the positive samples (90 %) were collected
between January and April. The largest number (43 %) of infected cats was documented in
April.

Symptoms shown by infected cats agree with the results of studies concerning Songbird fever.
The most common symptoms in ascending order were; fever, vomiting, depression, anorexia,
diarrhea and abdominal pain.

The distribution of cases of Songbird fever was unevenly distributed in Sweden. Stockholm
County, which has the largest insured population of cats in Sweden, according to Agria
statistics, had the largest number of cases. It appears that Uppsala and Gävleborg County had
a larger number of cases than expected when compared to the distribution of insured cats in
Sweden. The reasons for this can be many. Maybe the distribution of the bacteria varies. It is
also possible that cat owners´ motivation for going to the vet varies. Routines involved in
sample testing and levels of knowledge may also vary between different parts of the country.

The number of unrecorded cases of Salmonella in cats in Sweden could very well be quite
high.