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Group G Streptococcal (Strep G or G-Strep)

Updated: Apr 2, 2020

Group G Streptococcal also referred to as Lancefield group G or Streptococcus canis (S. canis) nicknamed G-strep is typically non-disease causing and is actually part of the normal microflora of the body. It can be found in the digestive tract, reproductive tract including organs of the genitals, respiratory tract including oral cavities, and on the skin (1, 2, 3, 4). It can also be found in the tonsillar and ear microbiota of cats and dogs. G-Strep, however, can become disease-causing and ironically there is little difference in the chemical process between S. canis strains cultured from healthy and infected animals (1).

DIAGNOSIS There are diagnostic tests specifically for G-Strep, however, it seems that more times than not there are more false NEGATIVES, therefore reliability is fairly low. Diagnosis can be somewhat difficult primarily for veterinarians and even breeders. Most will dismiss symptoms as other causes or will not “connect the dots”. As you will see below, there is a wide range of symptoms that seem unrelated, but indeed can be correlated to other situations. Often times a slew of overlapping symptoms, versus diagnostic tests, lead one to treat for G-strep.

Incubation of G-Strep is typically expensive as it takes about 10 days to culture. Many vets choose broad spectrum treatments and often G-Strep is mistaken for upper respiratory infections as well as other co-occurring illnesses such as calicivirus, panleukopenia, and chlamydia which could be present at the same time and overshadowing underlying causes.

Polymerase Chain Reaction (PCR) tests and a bacterial culture are recommended to be performed to help rule out or address underlying illnesses that may be presenting with (or independently of) G-strep.

In breeding animals vaginal cultures are recommended as well. Other tests or methods can include blood break down patterns, characteristics of bacterial colonies, biological and chemical reactions, and tests that identify antibodies in the blood. Presumptions can be made from smears, tissue samples and secretions taken from the airways if cocci are seen in pairs or chains (5). Lesions also may be present. Bacteria can be found in wounds, blood, brain and spinal fluid, placenta, tissues of fetuses, etc (5). In kittens diagnosis can also be made via positive test results in the placenta and umbilical cords of aborted kittens.

SYMPTOMS/RESULTS/PRESENTATION Symptoms, unfortunately, are widespread and many. They may seem completely unrelated or you may be able to attribute them to other situations in your breeding cats. The following are symptoms reported by breeders and research studies:

  • Bred two seemingly healthy cats numerous times, but did not result in pregnancy

  • A bred cat results in pyometra instead of pregnancy

  • A mother delivers a whole litter of stillborn kittens or large percentage of stillborns in a litter (6,7)*

  • A queen aborts litters (6, 7)*

  • Litter sizes have dropped

  • Females have stopped calling

  • Spontaneous death of seemingly healthy kittens (6, 7)*

  • Kittens suddenly being born with birth defects (i.e. intestines outside the body)

  • Dermatitis (skin inflammation) (8, 9, 10)

  • Otitis Externa (inflammation of the ear) (8, 9, 10)

  • Pneumonia (8, 9, 10)

  • Infective Endocarditis (infection of the heart lining) which may also cause fever, heart murmurs, petechiae (tiny circular patches on the skin), anemia, embolic phenomena (purple skin discoloration) (8, 9, 10)

  • Adult Septicemia (8, 9, 10)

  • Arthritis (5)

  • Wound Infections (5)

  • Cervical lymphadenitis (swollen lymph nodes in the neck) in 3-6 month old kittens (5)

  • Streptococcal Toxic Shock Syndrome (5)

  • Swollen, infected umbilical cord (5)

  • Mastitis (inflammation of breast tissue) (5)

  • Pleuritis (inflammation of the membrane that lines the chest and surrounds the lungs) (5)

  • Lower airway inflammation with mucous (5)

  • Abscesses or lesions (5)

  • Discospondylitis (infection of the vertebrae and the surrounding cartilaginous discs

  • Osteomyelitis (infection of the bone)

  • Polyarthritis (arthritis of more than four joints)

  • Sexually transmitted infections

  • Sinus Infection

  • Meningitis (inflammation of the brain and spinal cord membranes)

*G-strep has been connected with blood poisoning of unborn or newborn kittens

HOW As mentioned G-strep is naturally found in the body. When the body is out of sync this bacteria can over grow causing disease. Factors that can influence whether Streptococcal G causes disease:

  • The amount of maternal antibodies present

  • Immune response

  • Age

  • Number of pathogenic microorganisms and their ability to infect the animal

  • Stress

  • Damage caused by the specific strain

  • G-strep can also spread via grooming, breeding, from mother to kitten and through wounds (5)

Now you understand how elusive G-strep is. It's easy to transmit, difficult to diagnose, and harder to get rid of. PREVALENCE In one major study performed on 394 cats and dogs 58 or 18% of dogs and 9 or 12.7% of cats tested positive for S. canis, 21.4% of which were cultured from the rectum (1). 70-100% of queens in a cattery setting host the bacteria in their vagina, which results in the infection of kittens HOWEVER that being said some mothers will pass immunity against the bacteria via their colostrum. Kittens of younger mothers are more often affected (5). In 10% of cats with upper respiratory infections, S. canis has been cultured.

CARRIERS It seems that most cats are carriers but don’t actually present symptoms. Even stranger is that many carriers don’t shed when stressed like other types of carriers yet pass it to others via grooming practices.


With Streptococcal G being a bacteria the go to treatment is often an antibiotic however not all antibiotics are effective on G-Strep, and many strains actually have become resistant to antibiotics that previously have worked. In one study all cultures were susceptible to penicillin and ampicillin however only 33.8% were susceptible to tetracycline, 10.5% to vancomycin, 7% to chloramphenicol, 3.5% erythromycin and 2.3% to clindamycin (1). Wu et al. (1997) confirmed 38.2% of cultures were not susceptible to erythromycin and 73.5% to tetracycline. To further validate these findings yet another study showed susceptibility to penicillin, cefotaxime, chloramphenicol, levofloxacin, vancomycin, quinupristin-dalfopristin, linezolid, and gentamicin. 27% of cultures were resistant to tetracycline (11). In the past clindamycin was the medication of choice but with that now being the antibiotic that most cultures are resistant to it is no longer recommended. Previous protocols are as follows: Clindamycin, 25 mg per 6-10 lbs, twice a day for 20 days.

All cats in the program including kittens as well as any spayed or neutered cats in your home should be treated. Before breeding when a female starts calling dose with 25 mg twice a day for 2-3 days with clindamycin. After 2-3 days put the female in with the male and dose both until the female is done her heat or for one week. 1 week before birth administer 25 mg of clindamycin twice daily. Continue 3-5 days following the birth. 5-10 days before giving birth administer 1cc/mL of Clavamox and/or azithromycin twice a day. Following birth administer 1 cc penicillin subcutaneously immediately to the mother. Newborns immediately dip the umbilical cord in iodine*. Also administer long lasting penicillin (benzathine/procaine pen G which can be bought without a prescription at Tractor Supply or other farm stores) subcutaneously. The penicillin should be diluted for newborn kittens. The mixture should consist of 1.5 cc sterile water + 0.25 cc/mL long lasting penicillin. Administer 0.25 cc/mL of this mixture subcutaneously to each kitten. *(It is no long recommended to DIP the umbilical cord, rather to keep everything sterile SWAB the umbilical cord with a clean Q-tip.)

Current Protocol There are many protocols that breeders have developed or modified from the above. The protocol that has been passed on to me by Candie Losee of Arkham Bengals is as follows. Treatment of all cats and kittens in the home for 21 days. Treat every other day with benzathine/procaine penicillin subcutaneously dosed as follows:

1 mL per 10 lbs of cat

1 mL for females

1.5 mL for large adult males All kittens up to 5-6 weeks old should be given the diluted dose. 1.5 cc sterile water + 0.25 cc/mL long lasting penicillin. Administer 0.25 cc/mL of this mixture subcutaneously to each kitten. Completely treat in this manner every 3 years there after. Doses may need to be spaced out such as far as every three days instead of every two days.

If for some reason a cat has a reaction, do not treat this cat again. At birth kittens should be given one dose of the penicillin mixture noted below

1.5 cc sterile water + 0.25 cc/mL long lasting penicillin.

Than give 0.25 cc of the mixed solution to each kitten. You will also want to swab the umbilical cord in iodine with clean a q tip within a few hours of birth. Tylan also has been used by breeders. Jessica Petras of Liberty Bengals shared this information. Tylan is a powder that is not an antibiotic but it stops the growth of G-strep and leaves the immune system to take over, therefore it is a bacteriostatic. It can be purchased with a prescription via a veterinarian or Tylan is packed into size four capsules and administered to adults twice a day for three weeks.

Kittens are still swabbed with iodine at birth. Kittens are not treated but given clavamox or amoxicillin if diarrhea is present but due to the thickness of the medication, tube feeding medications may be recommended to avoid aspiration. If one is uncomfortable with this method they may also administer the diluted penicillin subcutaneously noted above.

VACCINES There are no vaccines for this bacteria (5).

PREVENTION Streptococcus bacteria are typically eradicated via detergents and common disinfectants including 1% sodium hypochlorite, 70% ethanol, formaldehyde, glutaraldehyde, and iodine-based disinfectants. The bacteria also can be treated with moist heat at 121 degrees celsius for 15 minutes minimum, or dry heat at 160-170 degrees celsius for at least 1 hour (5).

Sources and Articles

1. Lysková, P & Vydržalová, M & Královcová, D & Mazurová, J. (2007). Prevalence and Characteristics of Streptococcus canis Strains Isolated from Dogs and Cats. Acta Veterinaria Brno - ACTA VET BRNO. 76. 619-625. 10.2754/avb200776040619.


2. DEWINTER LM, LOW DE, PRESCOTT JF 1999: Virulence of Streptococcus canis from canine streptococcal toxic shock syndrome and necrotizing fasciitis. Vet Microbiol 70: 95-110 3. MILLER CW, PRESCOTT JF, MATHEWS KA, BETSCHEL SD, YAGER JA, GURU V, DEWINTER L, LOW DE 1996: Streptococcal toxic shock syndrome in dogs. J Am Vet Med Assoc 209: 1421-1426

4. BORNAND V 1992: Bacteriology and mycology of otitis externa in dog. Schweiz Arch Tierheilkd 134: 341-348 5. The Center for Food Security and Public Health, and Institute for International Cooperation in Animal Biologies. “Streptococcosis.” Http://, May 2005,

( 6. Devriese LA, Hommez J, Kilpper-Balz R, Schleifer K-H. 1986. Streptococcus canis sp. nov.: a species of group G streptococci from animals. Int. J. Syst. Bacteriol. 36:422–425.

7. Lyskova P, Vydrzalova M, Mazurova J. 2007. Identification and antimicrobial susceptibility of bacteria and yeasts isolated from healthy dogs and dogs with otitis externa. J. Vet. Med. A Physiol. Pathol. Clin. Med. 54:559–563.

8. Lamm CG, Ferguson AC, Lehenbauer TW, Love BC. 2010. Streptococcal infection in dogs: a retrospective study of 393 cases. Vet. Pathol. 47:387–395 9. Sykes JE, Kittleson MD, Pesavento PA, Byrne BA, MacDonald KA, Chomel BB. 2006. Evaluation of the relationship between causative organisms and clinical characteristics of infective endocarditis in dogs: 71 cases (1992-2005). J. Am. Vet. Med. Assoc. 228:1723–1734 10. WU JJ, LIN KY, HSUEH PR, LIU JW, PAN HI, SHEU SM 1997: High incidence of erythromycin-resistant streptococci in Taiwan. Antimicrob Agents Chemother 41: 844-846 11. Multilocus Sequence Analysis of Streptococcus canis Confirms the Zoonotic Origin of Human Infections and Reveals Genetic Exchange with Streptococcus dysgalactiae subsp. equisimilis

M. D. Pinho, S. C. Matos, C. Pomba, A. Lübke-Becker, L. H. Wieler, S. Preziuso, J. Melo-Cristino, M.Ramirez

Journal of Clinical Microbiology Mar 2013, 51 (4) 1099-1109; DOI: 10.1128/JCM.02912-12 ( Lyskova P, Vydrzalova M, Mazurova J. 2007. Identification and antimicrobial susceptibility of bacteria and yeasts isolated from healthy dogs and dogs with otitis externa. J. Vet. Med. A Physiol. Pathol. Clin. Med. 54:559–563.

Clemetson LL, Ward AC. 1990. Bacterial flora of the vagina and uterus of healthy cats. J. Am. Vet. Med. Assoc. 196:902–906.

Devriese LA, Cruz Colque JI, De Herdt P, Haesebrouck F. 1992. Identification and composition of the tonsillar and anal enterococcal and streptococcal flora of dogs and cats. J. Appl. Bacteriol. 73:421–425.

Watts JR, Wright PJ, Whithear KC. 1996. Uterine, cervical and vaginal microflora of the normal bitch throughout the reproductive cycle. J. Small Anim. Pract. 37:54–60.

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