/ Yellow fever/ yellow bag
- cow which has been acting depressed for the last 24 hours, and has failed to remain with the herd. The cow’s temperature is 104F, (40 C), heart rate is 100 bpm and is pounding loudly, and the respiratory rate is elevated at 42 breaths per minute. The mucous membranes are pale. You take a blood sample back to your nearby clinic and observe the blood smear (see image). The PCV is 20% (24-46%). Of the following, what is the single best, most cost-effective treatment for this cow?
- The blood smear shows multiple round Anaplasma marginale along the outer membrane of red blood cells.
- Anaplasma marginale is an obligate intracellular bacterium. It is the most prevalent tick-borne pathogen of cattle worldwide and is endemic in tropical and sub-tropical regions. Canada is Anaplasma-free. Infection causes large scale destruction of red blood cells and fever, weight loss, respiratory distress, abortion, and often death. Although some cattle recover, they can become lifetime carriers as reservoirs. Anaplasma ovis can occur in sheep and goats.
- Anaplasma can often be treated successfully with a single injection of long acting tetracycline (20 mg/kg). When the PCV is below 12%, a blood transfusin may also be needed. In addition, the animal should be given ready access to feed and water. Even with treatment, animals may remain carriers after all clinical signs resolve.
- You are called by a rancher and asked to examine a 3-year old beef cow he purchased 4 weeks ago and turned out in the hills of California. The complaint is that she appears weak and disoriented, and even a little belligerent. On exam, you find T=105F or 40.6 C, HR=110, and RR=45. The heart is pounding very loudly and you note a number of ticks on her. Mucous membranes are pale (see image of her vulva), but urine and feces appear normal. Other parameters are not notably abnormal. Which of the following diseases best fits this cow`s clinical signs?
- This tick-borne disease has an incubation period of 2 to 4 weeks, and causes these exact signs. Tetracycline is the best treatment.
- With piroplasmosis or Clostridium novyi type D infection (bacillary hemoglobinuria), one would expect intravascular hemolysis and dark urine.
- On a side note, we at VetPrep recommend wearing gloves when performing this sort of exam.
- Anaplasmosis. The causative agent is Anaplasma marginale. The clinical signs are fairly straight forward, and you need to pick up on a couple key features. The fact that new adults are sick is one feature because cattle are resistant to clinical Anaplasmosis as calves. Also, it should be remembered that hemoglobinuria with Anaplasmosis is never seen because it is all extravascular hemolysis. there ll be no hemoglobinuria, leptospirosis, bacillary hemoglobinuria, and anthrax can be ruled out. Additionally, icterus with anthrax is not seen.
- Anaplasmosis, formerly known as gall sickness, traditionally refers to a disease of ruminants caused by obligate intraerythrocytic bacteria of the order Rickettsiales, family Anaplasmataceae, genus Anaplasma. Cattle, sheep, goats, buffalo, and some wild ruminants can be infected with the erythrocytic Anaplasma. Anaplasmosis is characterized by progressive anemia due to extravascular destruction of infected and uninfected erythrocytes.