2. Bacterial diseases

#### 2.1. Brucellosis

The bacterium Brucella canis (small, aerobic Gram‐negative coccobacilli, which stain red using the modified Ziehl‐Neelsen technique) stands out as one of the main bacterial causes of pregnancy loss in bitches [2]. The species B. abortus, B. melitensis and B. suis have also been found in dogs, where it is believed that the natural infection occurs after the ingestion of placenta and aborted foetuses. The main source of infection is through vaginal and seminal secretions from infected animals, although bacteria are shed in faeces, milk, saliva, and nasal and ocular secretions [2]. The B. canis may be present for a long time in dogs without exhibiting clinical signs. After the initial exposure, the bacteria reach the bloodstream in about three weeks. Subsequently, the pathogen can infect the genital tissues enabling a continuous release of the agent, which may be recurring for months or even years. In turn, canine brucellosis can result in infertility, difficulties in pregnancy, early embryonic death, foetal resorption and late abortion. The clinical signs associated with Brucellosis in dogs are not pathognomonic and due the lack of the lipopolysaccharide antigen associated with endotoxemia in bitches, it is rarely systemic ill and fever [3]. Clinical signs reflect the localization of the bacteria in extra reproductive tract sites such as the eye, intervertebral disc spaces, and reticuloendothelial system. Brucellosis causes spontaneous late abortion in a healthy bitch, most commonly occurs from days 30 to 57, accompanied by a vaginal discharge lasting up to 6 weeks. Earlier abortions can occur but may be incorrectly reported as conception failure since the bitch typically ingests aborted foetuses. Early embryonic death and foetal resorption can occur within 10 – 20 days post‐mating. Many bitches that abort will subsequently have normal litters, although puppies born to infected bitches contain both live and dead pups, although most live pups die shortly thereafter. Aborted puppies usually appear partially autolysed, with lesions of generalized bacterial infection, including subcutaneous oedema and degenerative lesions in the liver, spleen, kidneys and intestines. Seroprevalence studies indicate that canine brucellosis is widespread in the Americas. Isolation (placenta, lymph nodes, prostate, and spleen are suitable samples for culture) and identification of B. canis is the gold standard, however, serology (the most accurate serological test currently available is the agar gel immunodiffusion test‐AGID) and polymerase chain reaction (PCR) are widely used to diagnose canine brucellosis [3, 4]. B. canis is not considered a significant zoonosis and, serious illness can occur in immunocompromised patients by direct contact with infected animals or through occupational aerosol exposure, but the owners should be aware of the zoonotic potential of this disease [4].

#### 2.2. Others bacterial agents and Rickettsias

The Ehrlichia canis and Anaplasma platys have been found in dogs attended in veterinary hospitals and clinics in various countries and states in Brazil [1]. Anaemia and thrombocytopenia are the main clinical signs found in dogs infected with these agents in Brazil. However, it is noted that these dogs more often develop anaemia and thrombocytopenia. So, clinical signs may vary according to geographical variations and pathogenicity. These agents are not yet known to cause abortion directly but have been reported in abortion in anaemic bitches infected. Results also indicate that animals with infectious anaemia may be more susceptible to suffer reproductive failures than animals with normal haematological values [1] (Figure 1).

overcome the placenta, but they are also able to affect pregnancy and release placental toxins by inflammatory processes and may still cause maternal pathologies, which entail problems such as hyperthermia, hypoxia and endotoxemia, which can result in reproductive failures

The bacterium Brucella canis (small, aerobic Gram‐negative coccobacilli, which stain red using the modified Ziehl‐Neelsen technique) stands out as one of the main bacterial causes of pregnancy loss in bitches [2]. The species B. abortus, B. melitensis and B. suis have also been found in dogs, where it is believed that the natural infection occurs after the ingestion of placenta and aborted foetuses. The main source of infection is through vaginal and seminal secretions from infected animals, although bacteria are shed in faeces, milk, saliva, and nasal and ocular secretions [2]. The B. canis may be present for a long time in dogs without exhibiting clinical signs. After the initial exposure, the bacteria reach the bloodstream in about three weeks. Subsequently, the pathogen can infect the genital tissues enabling a continuous release of the agent, which may be recurring for months or even years. In turn, canine brucellosis can result in infertility, difficulties in pregnancy, early embryonic death, foetal resorption and late abortion. The clinical signs associated with Brucellosis in dogs are not pathognomonic and due the lack of the lipopolysaccharide antigen associated with endotoxemia in bitches, it is rarely systemic ill and fever [3]. Clinical signs reflect the localization of the bacteria in extra reproductive tract sites such as the eye, intervertebral disc spaces, and reticuloendothelial system. Brucellosis causes spontaneous late abortion in a healthy bitch, most commonly occurs from days 30 to 57, accompanied by a vaginal discharge lasting up to 6 weeks. Earlier abortions can occur but may be incorrectly reported as conception failure since the bitch typically ingests aborted foetuses. Early embryonic death and foetal resorption can occur within 10 – 20 days post‐mating. Many bitches that abort will subsequently have normal litters, although puppies born to infected bitches contain both live and dead pups, although most live pups die shortly thereafter. Aborted puppies usually appear partially autolysed, with lesions of generalized bacterial infection, including subcutaneous oedema and degenerative lesions in the liver, spleen, kidneys and intestines. Seroprevalence studies indicate that canine brucellosis is widespread in the Americas. Isolation (placenta, lymph nodes, prostate, and spleen are suitable samples for culture) and identification of B. canis is the gold standard, however, serology (the most accurate serological test currently available is the agar gel immunodiffusion test‐AGID) and polymerase chain reaction (PCR) are widely used to diagnose canine brucellosis [3, 4]. B. canis is not considered a significant zoonosis and, serious illness can occur in immunocompromised patients by direct contact with infected animals or through occupational aerosol expo-

sure, but the owners should be aware of the zoonotic potential of this disease [4].

The Ehrlichia canis and Anaplasma platys have been found in dogs attended in veterinary hospitals and clinics in various countries and states in Brazil [1]. Anaemia and thrombocytopenia are the

2.2. Others bacterial agents and Rickettsias

(abortion, stillbirth and neonatal death) [1].

56 Canine Medicine - Recent Topics and Advanced Research

2. Bacterial diseases

2.1. Brucellosis

Figure 1. Macroscopic lesions caused after abortion due anaemia occasioned by vector‐borne disease. (A). Anaemic vulva after intense parasitaemia by ticks; (B). uterus with haemorrhagic serous after episode of abortion; (C). hepatosplenomegaly in aborted foetus with 56 days of gestation; (D). foetus with blackened organs and in the autolysis process after stillbirth in late pregnancy.

Escherichia coli is the most common bacterium isolated from the canine vagina and is also commonly cultured from the uteri of bitches with metritis and pyometra. E. coli produces an endotoxin that may result in pregnancy loss in the bitch. Streptococcus spp are bacteria that are physically present in the skin and mucosa of dogs and cats. Some microorganisms belonging to this group have been related to the occurrence of neonatal sepsis, abortion and metritis [2, 3]. βH Streptococcus is known cause metritis, pyometra, placentitis and abortion, commonly linked to ascending infection. Streptococcus βH is a major cause of neonatal death. Typically, newborns are infected in the mother's birth canal, through the umbilical cord or, less commonly, from the udders with mastitis. Bitches have high bacterial load in the vaginal canal, which persist throughout pregnancy leading to the infection of the uterus and foetus [2, 3].
