The "ick" in tick
Ticks are an issue we are all too familiar with. Following is an outline of how to manage the "ick" in several common tick-related diseases.
Ehrlichiosis
Dogs affected with ehrlichiosis will develop symptoms approximately 8-20 days after infection.1 There are acute and chronic stages of Ehrlicia though it is difficult to distinguish between the stages.1 Acute signs may last 1-3 weeks and are generally resolved after 4 weeks.1 Initial signs may be subtle, and include lethargy, anorexia, and fever.1 More commonly the acute symptoms are hallmarked by inflammation and thrombocytopenia.3 As a result of the thrombocytopenia, epistaxis, melena, petechial and ecchymotic hemorrhage, retinal hemorrhage, anemia, and hematuria may be seen.3 It may be possible for the dog to resolve signs/symptoms without treatment. The organism may replicate in the reticuloendothelial tissues (macrophage areas), which may result in enlarged lymph nodes, edema, and splenomegaly.3 Rarely the dog may experience eye disease and central nervous system symptoms such as ataxia, nystagmus, or seizures.3
Chronic stage symptoms range from mild to severe. The symptoms are similar to the acute form, but will be exaggerated as they have had the disease for an extended time. They will be stiff, perhaps unable to move, bleeding is more common, and edema may be worse.
Anaplasmosis
Approximately 1-2 weeks after initial infection with anaplasmosis, dogs will experience symptoms that may start as nondescript (anorexia, lethargy, fever).1 In a similar fashion to ehrlichiosis, the pet will experience stiffness, lameness with rare vomiting/diarrhea, and CNS signs.1 Sometimes a nonproductive cough may develop. Most pets will present with a polyarthritis, which is similar to those infected with Lyme disease, making it difficult to distinguish between the two.4 In more than 80% of cases a mild to severe thrombocytopenia occurs, though the pet is not often symptomatic.4
Borreliosis (Lyme disease)
Approximately 24-48 hours after infection, the spirochete is transmitted through the saliva of the tick into the animal.5,6 It is well known that dogs can be infected, but never become symptomatic. 5 It is unknown why some dogs will become symptomatic and even develop life-threatening conditions. Roughly 5-10% of infected dogs will develop disease symptoms about 2-5 months after infection. 5
Symptoms may start with lethargy, anorexia, and fever. Usually they quickly progress to lameness (shifting leg), polyarthritis, and lymphadenopathy.5 Arthritis and consequently lameness begin in the joint closest to the tick bite though often the symptoms progress so quickly that owners are unaware which leg was affected first. 5 Owners often describe the pet as "fine this morning" or "limping a little this morning" to "now won't move at all" or "limping everywhere", and often describe the symptoms worsening in less than 24 hours.
While most symptomatic dogs present in a similar manner there are more rare life-threatening syndromes that may occur. Lyme nephritis (protein-losing glomerular disease), myocarditis, and neurologic disease can occur as a result of infection from the burgdorferi spirochete. It is not known if dogs experience chronic reoccurring symptoms as people do, but at this time it is not thought to be the case.5,6 While only 1-2% of dogs will develop nephritis, all positive dogs should be screened and monitored for proteinuria and renal disease. Nephritis signs often mimic those of leptospirosis so dual testing should be performed on these dogs.
Rocky Mountain Spotted Fever (RMSF)
German Shepherds appear predisposed to developing some of the most severe signs of RMSF.1 Like most tick-borne illnesses, the signs are non-specific, including lethargy, anorexia, vomiting, abdominal pain, and enlarged lymph nodes.1 Sometimes edema of the limbs will occur.1 The dog typically becomes stiff and lame. Ocular issues may start including mucopurulent discharge, scleral injection, and uveitis.1 Thrombocytopenia occurs in 85% of dogs.7 As a result, petechiae and/or ecchymoses may develop. In more than 80% of dogs neurologic signs have been reported, including ataxia, stupor, vestibular signs, hyperesthesia, and seizures.1 As the disease progresses the dog may develop myocarditis, liver and renal failure.1 Death ultimately occurs from organ, heart, or central nervous system failure.
Cytauxzoonosis
More than 90% of all cases of cytauxzoonosis will be diagnosed between April and September of each year. 7 The protozoan specifically attacks the vascular system of the kidneys, brain, lungs, liver, and spleen.8 Most of the time owners will notice that their cats are depressed, not eating, and have pale mucous membranes. Thrombocytopenia is one of the most common findings in cats.7 Cats usually present as anemic, icteric, and severely ill. Within 5-6 days after infection, there will typically be a decrease in the packed red blood cell volume.7 There is a >90% mortality rate associated with this disease.8
American hepatozoonosis
Typically a pet infected with American hepatozoonosis will show nondescript signs such as intermittent fever, weight loss, lameness, and anorexia.9 Signs may progress to stiffness and fever despite the use of antibiotics and pain.9 Osteoproliferation can be seen typically in the long bones on radiograph.9 Long-term complications most commonly include kidney failure, interstitial nephritis, and glomerulonephritis.9
References
1. Ettinger, S, Feldman E, Textbook of Veterinary Internal Medicine: Expert Consult Online and Print, 7th edition, Sykes, J, Chapter 206 – “Ehrlichia, Anaplasmosis, Rocky Mountain Spotted Fever, and Neorickettsial Infection”, Elsevier Saunders, Accessed online through Expert Consult: expertconsultbook.com on 6/8/2014.
2. Wysong Rudolph L, Diagnosing and Treating Tick-Borne Diseases, ABVP 2012 Proceedings. Accessed online through VIN (vin.com) on 6/8/2014.
3. Blagsburn, B, Managing Fleas, Ticks, and Vectorborne Diseases in a Practice Environment. Atlantic Coast Veterinary Conference 2013 Proceedings. Accessed online through VIN (vin.com) on 6/8/2014.
4. Alleman R, Wamsley H, An Update on Anaplasmosis in Dogs, Veterinary Medicine Magazine, 2008, Accessed online through www.veterinarymedicine.dvm360.com on June 8, 2014.
5. Ettinger, S, Feldman E, Textbook of Veterinary Internal Medicine: Expert Consult Online and Print, 7th edition, Goldstein R, Chapter 199 – “Lyme Disease”, Elsevier Saunders, Accessed online through Expert Consult: expertconsultbook.com on 6/8/2014.
6. Barr S, Lyme disease: Vaccinate, treat or do nothing? CVC Baltimore Proceedings, 2009.
7. Hoskins J, Diagnosis, treatment of tick-borne diseases, DVM Magazine 360, May 1, 2009, Accessed online through www.veterinarymedicine.dvm360.com on June 8, 2014.
8. McGavin M, Zachary J, Pathologic Basic of Veterinary Disease: 4th Edition, Chapter 13, “Bone Marrow, Blood Cells and Lymphatic System”, pp. 782-793, Mosby Elsevier, St. Louis, MO, 2007.
9. Strain M, Pugh T, "A challenging case: A dog with intermittent pain and fever", Veterinary Medicine Magazine, Dec 1, 2006, Accessed online through www.veterinarymedicine.dvm360.com on June 16, 2014.
Amy is currently employed at BluePearl Massachusetts in Waltham, MA as the Emergency Head Technician. In 2003 she became boarded as a Veterinary Technician Specialist in Emergency and Critical Care. She currently sits on the Academy of Veterinary Emergency & Critical Care Technicians board as the President-Elect. Amy is well published in over 15 subjects, is an international speaker, has received numerous awards and highly involved in her community. Most recently Amy was awarded the Speaker of the Year at the 2014 NAVC Conference. She lives in Massachusetts with her husband and wonderful furry kids.
This article is based on Ms. Breton’s presentation at the Veterinary Emergency and Critical Care Society Conference in Indianapolis, IN.CVT
