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Trichomoniasis in Animals


Introduction

Trichomoniasis is a protozoan disease caused by flagellated protozoa of the genus Trichomonas. In veterinary medicine, it is most important as a venereal disease in cattle, causing early embryonic death, infertility, and occasional abortion. It is primarily a herd-level reproductive disease rather than a systemic illness.

Etiology
Causative Agents
  • Tritrichomonas foetus (bovine trichomoniasis – most important)
  • Trichomonas gallinae (birds – crop infections, “canker” in pigeons and falcons)
  • Tritrichomonas blagburni (feline large intestinal trichomoniasis, especially cats)
Organism Characteristics
  • Flagellated protozoa
  • No cyst stage (important for transmission dynamics)
  • Extracellular parasites
  • Reside in reproductive or mucosal surfaces
Epidemiology
Species Affected
  • Cattle (major economic importance – venereal disease)
  • Cats (chronic diarrhea in kittens and young cats)
  • Birds (pigeons, raptors)
Transmission
  • Venereal transmission in cattle (natural service)
  • Contaminated semen in artificial insemination
  • Direct oral transmission in birds (feeding, water contamination)
  • Fecal-oral transmission in cats
Risk Factors
  • Use of infected bulls
  • Natural breeding systems
  • Lack of reproductive screening
  • Herd management deficiencies
Pathogenesis
Reproductive Tract Infection (Cattle)

T. foetus colonizes the vagina, uterus, and sometimes oviducts.

Inflammation and Endometritis
  • Uterine inflammation
  • Disruption of normal fertility processes
Embryonic Death
  • Early embryonic loss (most common outcome)
  • Occasional abortion in mid-gestation
Carrier State
  • Bulls often asymptomatic carriers
  • Older bulls more likely to harbor organisms in preputial crypts
Clinical Signs
In Cattle
  • Infertility in breeding cows
  • Irregular returns to estrus
  • Early embryonic death
  • Occasional abortion (1–4 months gestation)
  • Pyometra in some cases
In Bulls
  • No clinical signs (important reservoir)
In Cats (Tritrichomonas blagburni)
  • Chronic large bowel diarrhea
  • Fecal incontinence in severe cases
  • Young cats more commonly affected
In Birds (T. gallinae)
  • Oral lesions (“canker”)
  • Difficulty feeding
  • Weight loss and mortality in severe cases
Summary for Practitioners

In cattle, trichomoniasis should be suspected in herds with infertility and early pregnancy loss, especially where natural mating is practiced.

Postmortem Findings
Gross Lesions
  • Uterine inflammation (endometritis)
  • Fetal resorption or small aborted fetuses
  • Pyometra in chronic cases
  • No specific lesions in bulls
Microscopic Lesions
  • Inflammatory infiltrates in reproductive tract
  • Presence of protozoa in mucosal surfaces
Diagnosis
Clinical Diagnosis

Based on herd infertility patterns and reproductive history.

Laboratory Diagnosis
  • Culture of preputial or vaginal samples
  • PCR (highly sensitive and specific)
  • Microscopic examination of fresh samples
Sampling
  • Bulls: preputial smegma
  • Cows: vaginal mucus, uterine discharge
Differential Diagnosis
  • Brucellosis
  • Campylobacteriosis
  • Leptospirosis
  • Non-infectious infertility causes
Summary for Practitioners

Repeated testing is often required in bulls due to intermittent shedding.

Treatment
Cattle
  • No consistently effective treatment for infected bulls
  • Culling of positive bulls is commonly recommended
Cats
  • Ronidazole (most effective treatment)
Supportive Care
  • Management of secondary uterine infections in cows
Summary for Practitioners

Control in cattle relies more on prevention and culling than treatment.

Control and Prevention
Breeding Management
  • Use of artificial insemination with tested semen
  • Avoid natural service in infected herds
Testing and Culling
  • Regular screening of breeding bulls
  • Removal of positive animals
Biosecurity
  • Quarantine new bulls before introduction
Summary for Practitioners

Effective control depends on strict breeding management and bull screening programs.

Zoonotic Importance

Trichomoniasis in veterinary species is not considered zoonotic.

Economic Importance

In cattle, trichomoniasis causes major economic losses due to infertility, prolonged calving intervals, reduced calf crop, and culling of valuable breeding bulls.

Summary

Trichomoniasis is a venereal protozoan disease of major importance in cattle reproduction. Control is based on prevention, testing, and removal of infected bulls rather than treatment.