Symptoms of Leptospirosis in Pets: What to Watch Out Fo

Characteristics of the Disease

Endemic in regions with warm climates and abundant rainfall, such as the banks of rivers, lakes, swamps, ponds, and paddy fields in tropical and subtropical zones, pathogenic Leptospira bacteria are widespread. Virtually all warmblooded pets are susceptible to infection, with rodents being the most common reservoir hosts, followed by carnivores.

Leptospira is primarily transmitted through direct contact with pets, via the skin, mucous membranes, and gastrointestinal tract. Other modes of transmission include mating, bites, consuming contaminated meat, and vertical transmission via the placenta. Bites from certain bloodsucking insects and other nonvertebrates can also lead to outbreaks. Infected dogs can intermittently or continuously excrete the bacteria in their urine, contaminating their surroundings, such as feed, water, pens, and other utensils. After clinical symptoms subside, dogs may carry a high titer of antibodies, excreting the bacteria intermittently via urine for several months to years, making them a dangerous carrier.

The disease has a distinct seasonal pattern, with summer and autumn being the peak periods. Dogs, particularly puppies, are more prone to the disease and exhibit more severe symptoms. High densities of dogs, malnutrition, or weakened immune systems can trigger clinical symptoms in dogs with latent infections, even leading to death.

Signs and Symptoms

The incubation period for the disease is typically 515 days. Acute infections present with fever, tremors, and widespread muscle tenderness. Symptoms include vomiting, rapid dehydration, and microcirculatory disturbances, rapid breathing, tachycardia, decreased appetite, and even anorexia, poor capillary refill, hematemesis, epistaxis, and melena. The body temperature may drop leading to death.

Subacute infections are characterized by fever, anorexia, vomiting, dehydration, and increased thirst. Affected dogs may have congested and bruised mucous membranes, with hemorrhagic spots. They may exhibit dry cough, dyspnea, conjunctivitis, rhinitis, and pharyngitis. Renal dysfunction may lead to oliguria or anuria. Dogs that survive this form may recover renal dysfunction symptoms 23 weeks after onset.

Acute or subacute infections caused by hemorrhagic jaundicetype Leptospira often present with symptoms such as jaundice, hepatitis, intrahepatic bile stasis, and graycolored feces. Severe cases may show signs of liver failure, weight loss, ascites, jaundice, or hepatic encephalopathy.

Uremia, foul breath, coma, or symptoms such as hemorrhagic gastritis and ulcerative gastroenteritis may also occur, leading to a high mortality rate.

Pathological Changes

Acute cases show visible changes such as jaundice of the skin, subcutaneous tissue, serous membranes, and mucous membranes, along with hemorrhages in the heart, lungs, kidneys, mesentery, intestines, and bladder mucosa. The intestines may be filled with tarry stools. Lymph nodes are enlarged and hemorrhagic. The liver is enlarged and appears brownish. The kidneys are enlarged with grayishwhite necrotic spots on the surface. Necrosis of the skin and subcutaneous edema may also occur.

Guidance

Acute and subacute cases have more pronounced clinical symptoms. A preliminary diagnosis can be made based on fever, jaundice of the mucous membranes, hemorrhage, and sticky yellow urine, combined with the degree of kidney and liver damage during postmortem examination and the epidemiological characteristics. Chronic cases are more challenging to diagnose due to不明显 symptoms and atypical lesions. A comprehensive diagnosis should be made by combining laboratory tests.

Differential Diagnosis

(1) Leptospirosis in Dogs vs. Canine Distemper

Both diseases present with fever, depression, anorexia, conjunctival congestion, and sometimes vomiting and diarrhea.

Distinguishing Features: Canine distemper is caused by the canine distemper virus. Affected dogs may exhibit neurological symptoms, such as difficulty standing, ataxia, or circular movements. They may have tonicclonic seizures or coma, with sequelae in surviving cases.

(2) Leptospirosis in Dogs vs. Canine Leukemia

Both diseases have fever, depression, anorexia, vomiting, and enlarged lymph nodes and spleen, along with similar pathological changes.

Distinguishing Features: Dogs with leukemia have an increased white blood cell count and a decreased red blood cell count. The disease is noncommunicable and has a very low incidence.

(3) Leptospirosis in Dogs vs. Canine Pyelonephritis

Both diseases present with fever, vomiting, and hematuria.

Distinguishing Features: Dogs with pyelonephritis may have renal pain, arching, and a stiff gait. The disease is noncommunicable, and the urine lacks the greasy appearance of leptospirosis. Lymph node swelling and jaundice of the mucous membranes are less common.

Preventive Measures

(1) Prevention

① Regularly inspect dog houses and eliminate rodents.

② Disinfect and clean contaminated water, areas, and utensils to prevent disease spread.

③ Administer vaccinations, such as multivalent bacterial vaccines, which offer protection for one year. Remember to get a booster shot annually.

④ Personnel in contact with sick dogs or cats should practice personal hygiene and protective measures.

(2) Treatment

The treatment principle is antibacterial and symptomatic therapy.

① Ampicillin, 2030 mg/kg body weight, orally, twice or thrice daily, or 1020 mg/kg body weight, intramuscularly, twice or thrice daily.

② Suprax (amoxicillin and clavulanate potassium suspension), 0.1 mL/kg body weight, subcutaneously or intramuscularly, once daily.

③ Streptomycin, 10 mg/kg body weight, intramuscularly, twice or four times daily.

④ Tetracycline, 1020 mg/kg body weight, orally, three times daily for 28 days.

⑤ Enrofloxacin (Baytril), 2.55 mg/kg body weight, orally, subcutaneously, or intravenously, twice daily; 12.5 mg/kg body weight, orally, twice daily for cats.

⑥ For cases with renal dysfunction, intravenous fluid therapy can be used to support the patient, while avoiding or reducing the dosage of streptomycin.