UNDERSTANDING BILIARY IN DOGS

COMMON PARASITES CAN CAUSE SERIOUS PROBLEMS

Ectoparasites, such as ticks, are more harmful to animals and humans than is generally  realised. Not only do they cause debilitating and irritating conditions themselves, but  they can transmit hazardous diseases to their hosts and humans. Certain zoonoses  (disease transmitted from animal to human) have increased in recent times due to the  rise of the pet population, with ticks and fleas being the main causative species.  

BILIARY FEVER (BABESIA) IN DOGS

Biliary is a serious tick-borne disease which affects the red blood cells of dogs, cats, horses and livestock.  Ticks transmit tiny infectious parasites into their host’s bloodstream where they multiply in the red blood cells  (erythrocytes) (Fig.1). During this continuous multiplication process many more red blood cells are invaded  and eventually destroyed (haemolysis) resulting in anaemia (Fig.2). This disease can be most troublesome as  the clinical signs may be acute, chronic, protracted or relapsing. 

CLINICAL SIGNS OF INFECTION

  • Fever
  • Anaemia (pale mucous membranes)
  • Anorexia and depression 
  • Vomiting
  • Dehydration
  • Jaundice (yellow mucous membranes) (See picture above)
  • Red urine (haemoglobinuria) 
  • Nervous signs

The ticks that prey on your pet are mainly the yellow dog tick (Haemaphysalis elliptica) and the kennel tick  (Rhipicephalus sanguineus) (Fig.3). Both are major transmitters of canine biliary fever (Babesia canis). In severe  infections death may occur very quickly, within as little as one day, unless there is an effective response to  treatment. Some animals in endemic areas will carry the disease, but without clinical signs, whilst in other  animals showing poor condition, the disease may have reached a chronic stage. Ticks attaching to such infected carrier dogs, will engorge blood cells containing Babesia sp. parasites. In the  tick’s digestive system these parasites undergo another developmental cycle, and by further multiplications  disseminate  throughout  the  tick’s  intestinal  cells  and,  more  importantly,  invade  various  organs  of  the  tick  including  the  ovaries  of  the  female  and  subsequent  eggs  laid  by  the  female.  This transmission  ensures  propagation of the Babesia sp. organisms to the next tick generation. This means that a certain percentage of  the larval stages of a Babesia-infected female tick pass the infection to dogs, without prior attachment to the  infected or carrier animals. Humans in close and frequent contact with infected animals are at risk of contracting tick-borne diseases, of which tick-bite fever (infection with Rickettsia conori) is the most common in South Africa. Tick-borne diseases are transmitted by the kennel tick  as  well  as  other  tick  species.  Of  late,  Congo  haemorrhagic  fever,  which  is  transmitted by the immature bont tick (Hyalomma spp.), also has to be considered  as an increasing human health hazard.

DIAGNOSIS AND SAMPLING

Blood samples, preferably from a capillary bed such as the ear tip as these are  richest in parasites, should be collected for parasite identification. This procedure  should only be done by a veterinarian.

EHRLICHIOSIS IN DOGS

Ehrlichiosis is a tick-borne rickettsial disease transmitted through the saliva of ticks. This bacterium infects  and kills the white blood cells. Clinical signs may be acute or chronic.

CLINICAL SIGNS OF INFECTION

  • Lethargy
  • Anorexia and weight loss
  • Fever
  • Bleeding tendencies (nose bleeds)
  • Nervous signs
  • Anaemia
  • Enlarged lymph nodes
  • Ocular pain  

TREATMENT

Treatment of biliary involves a visit to your local veterinarian, where he/she will recommend the best treatment  for the animal according to the clinical signs, often with a combination of products. He may also suggest  post-biliary supportive treatment for the animal that could be given at home.

PREVENTION

  • Babesiosis is normally transmitted by tick bites, so prevention depends on stopping the attachment  and feeding of ticks, which may be achieved by avoiding tick-infested areas and by using dips, spot-on  products or repellents with or without acaricides. 
  • Each treatment regime has its place in the control of ticks. Some are fast-acting but short-lived, while   others are long-acting. Some combat on-host parasites, while others the off-host parasites.
  • Depending on the severity and stage of the tick challenge, different products are recommended. Some products work only against ticks, while others have a combined efficacy to treat both ticks and fleas. Some products kill ticks while others repel and kill. A product that repels ticks reduces the risk of transmission of biliary fever.
  • Owners planning to travel with their dogs to areas where ticks are prevalent, should ensure that their dogs are adequately protected against ticks.
  • Babesiosis infection in a dog does not usually pose a direct risk for another dog, as blood transfer or ticks are needed for transmission of infection.

Printed here with permission of Bayer Animal Health.

References:  

1.  Fisher M, McGarry J. Focus on small animal parasitology. Leverkusen (Germany):
Bayer HealthCare AG, Animal Health Division; 2006. p. 62-4.

2.  Lobetti R. Canine and feline babesiosis. Vetmed 2007 Oct/Nov 20(5):15-17
Bayer (Pty) Ltd., Animal Health Division.  o. Reg. No. 1968/011192/07. 27 Wrench Rd, Isando, 1601, South Africa Tel: + 27 11 921 5573. Fax: +27 11 921 5762. www.bayeranimalhealth.co.za