Streptococcal infection in kittens

©Susan Little DVM, Diplomate ABVP (Feline Practice); http://www.catvet.homestead.com/Strep.html

Septicaemia is a significant cause of death in neonatal kittens, usually in the first week of life. Coliform septicaemia alone may account for up to 10% of deaths. Many factors can predispose kittens to neonatal septicaemia: failure of passive transfer of antibodies (inadequate colostrum intake, or inadequate antibody levels in the queen), high levels of pathogenic bacteria in the birth canal or from the queen (saliva, milk), unhygienic environment, failure of passive local immunity (inadequate nursing, or inadequate immunoglobulin levels in milk). Pathogenic bacteria may enter the kitten via the mouth, intestinal tract, genital or urinary tract, or umbilical cord. The most important routes of infection are the mouth and the umbilical cord. Kittens with gram-negative bacterial infections may appear healthy to within a few hours of death. In others, difficulty breathing from pneumonia may be the only sign. Deterioration is rapid as the kittens cease to nurse and become chilled before death. Queens will often refuse to care for such kittens. Diagnosis is reached at necropsy with culture of the umbilicus, liver, spleen, lungs, etc.

Fig.1. Kittens with streptococcal infections may die suddenly with no symptoms of illness and no visible lesions. This 5 day old Sphynx kitten was found dead unexpectedly with no signs of illness.

Omphalophlebitis (umbilical infection) results when pathogenic bacteria from the queen's saliva or the environment invade the umbilical cord. Normally, the queen chews off the umbilical cord a few inches from the body wall. The cord quickly dries which limits bacterial invasion of both the cord and the umbilicus. If the cord is severed too short, especially if it is severed flush with the abdomen, bacterial invasion may occur or an umbilical hernia may result. An abscess may form at the umbilicus, either just under the skin, or inside the abdomen. Bacteria may also enter the bloodstream via the umbilical vein (which stays partly open for several days) and cause septicaemia. The two most common agents of omphalophlebitis are haemolytic E. coli and Strep. canis. If the cause of the infection is not immediately known, antibiotics with coverage of both gram-negative and gram-positive organisms should be chosen (enrofloxacin [Baytril] 5 mg/kg plus cephalexin [Keflex] 22 mg/kg, once daily if under 2 weeks of age).

Fig. 2. Abdomen of Sphynx kitten that died from Strep G infection at 6 days old. Note the dark discolouration around the umbilical area.

S. canis was first identified as a cause of neonatal mortality in the mid-1980s at UC Davis. Most affected kittens die between 5 and 10 days. They may have no clinical symptoms of illness until hours before death, although they often gain weight slower than their uninfected littermates. A transient fever may be present in the 24 hours prior to death. Kittens are infected with the bacteria from the queen's vagina during birth. Usually not all of the kittens in the litter are affected. An abscess of the umbilicus spreads into the liver and abdominal cavity, leading to peritonitis and septicaemia. Some kittens may have an obvious umbilical abscess or swelling. The diagnosis is confirmed by culture of the umbilicus, liver, peritoneal cavity or lungs at necropsy. A second syndrome associated with S. canis is also seen where kittens develop abscessation of lymph nodes in the neck at about 3-6 months of age.

Fig. 3. Abdomen of another Sphynx kitten that died from a streptococcal infection. Note the very minimal reddish discolouration around the umbilicus which is the only sign of disease. All 4 kittens in this litter were born healthy but died by 1 week old.

S. canis is found in the vaginas of about 50% of young queens. The carriage rate in queens up to 2 years may be 100% in some catteries. Generally, the queens themselves are healthy. The highest incidence of infection is in kittens from the first litter born to a young queen (under 2 years). Older queens are more likely to have eliminated the bacteria spontaneously. Toms can also carry the bacteria in their prepuce, leading to rapid spread of the bacteria in a naive cattery. Antibiotic therapy is rarely effective in eliminating S. canis from a queen's vagina. However, a single dose of combined procaine and benzathine penicillin given to the queen at parturition may temporarily suppress the S. canis population and decrease risk of infection in the kittens.

Fig. 4. The abdominal cavity of a Sphynx kitten that died from acute septic peritonitis due to streptococcal infection. There is purulent fluid free in the abdomen. This cattery successfully treated its pregnant queens and had two healthy litters born within a month of the kitten losses to Strep. canis.

Kitten mortality from S. canis is the highest when the bacteria first enters a cattery. Thereafter, any naive queens entering the cattery may become infected and have a high mortality rate in their first litters. Most affected kittens die too quickly for effective treatment. Since S. canis is almost uniformly sensitive to penicillin, remaining littermates can be treated prophylactically with oral amoxicillin paediatric suspension (every 12 hours for 5 days). 

The risk of kitten mortality from S. canis can be managed prophylactically in catteries. The umbilical cord should be dipped in 2% tincture of iodine promptly after birth. In catteries experiencing recent kitten deaths from S. canis, kittens can be given a single SC injection of 0.25 ml of a 1:6 dilution in sterile 0.9% saline of product containing 150,000 IU/ml benzathine and procaine penicillin G. The queen is also given one SC injection of 150,000 IU of the same product (undiluted).

Reference:

Blanchard P, Wilson D. Group G streptococcal infections in kittens. In Kirk RW, Bonagura JD (editors): Current Veterinary Therapy X: Small Animal Practice, W.B. Saunders, Philadelphia, 1989, pp. 1091-1093.