How long can a dog survive with a paralysis tick?

In most infestations (except I holocyclus), removal of all ticks usually results in improvement within 24 hr and complete recovery within 72 hr. If ticks are not removed, death may occur from respiratory paralysis in 1–5 days. Removal of I holocyclus ticks does not immediately halt progression of disease. Clinical signs can deteriorate for ~24 hr and longer, but most dogs start to improve in 6–12 hr after TAS therapy. In any infestation, removal of all ticks is absolutely necessary. The entire integument should be searched, diligently and repeatedly, especially on long-haired animals or those with thick coats. Most ticks (80%) are located around the head or neck, but they can be found anywhere on the body. Plucking the tick(s) yields the best result (in dogs) and does not induce anaphylaxis.

Therapy for tick toxicity must address primary tick toxemia and paralysis, secondary issues (eg, esophageal reflux, aspiration pneumonia), and potential tertiary factors (eg, chronic weakness, esophageal stricture).

TAS is an immune serum against the toxin (similar to tetanus antitoxin) and is the product of choice. It should be given as early in the disease as possible; subsequent “top up” doses are not effective, because they are too late. For dogs, a minimal dosage of 0.5–1 mL/kg, should be given slowly IV throughout at least 20 min to avoid any shock reaction. Rapid IV use can induce clinical reactions in >80% of dogs. Anaphylaxis can occur unpredictably (as with all products), necessitating the use of high-dose, soluble cortisol and rapid fluid loading, etc. Based on retrospective case studies, cats are believed to be somewhat more susceptible than dogs, presumably with a second dose, a few weeks (not days) after the first dose.

Animals with multiple ticks or in the early stages of paralysis should receive a higher dose, because these cases have the most unbound toxin to neutralize. However, there are no data for the exact dosage rates required, and batch and brand levels of protective immunoglobulin may vary. Severely affected dogs may have less remaining unbound circulating toxin for TAS to neutralize. However, debate persists about the required (possibly less) dose of TAS. It has been suggested that a standard dose should be given, based on the amount needed to neutralize the pulsed toxin flow from one tick rather than on a weight basis; a minimal dose of 10–20 mL is recommended for dogs (and 5–10 mL for cats). However, until the level of remaining unbound toxin in the affected animal and the level of specific protective immunoglobulin can be better assessed, a set dose rate cannot be established (the level of disease is reflective of the level of bound toxin, which is not affected by TAS).

TAS given IP is the best alternative in cats for which the IV route is an issue (eg, respiratory distress, restraint dangers, dyspnea). However, its clinically effective half-life is believed to be short (days not weeks), and it will have no effect if the toxin is already tissue bound and the animal is severely ill or about to become so (with toxin in the perivascular space).

Minimization of stress and anxiety is essential. Acepromazine (0.03 mg/kg) may be given SC before any other medication or handling that may upset the animal. However, high doses should be avoided, especially if the animal is depressed, hypotensive, or hypothermic. (Overdosage may induce hypotension and hypothermia.) Opiates are an alternative (eg, methadone, 0.3–0.5 mg/kg, SC, IM). Oxygen therapy (nonstressful, usually nasal) is implemented (as indicated), but progressive disease requires more intensive therapy.

General anesthesia is indicated in animals that are severely fatigued and dyspneic, to allow for better administration of oxygen, esophageal drainage, and upper respiratory tract suction. Pentobarbitone can be used as a constant-rate infusion or given periodically IV to induce light anesthesia, with repeat doses as needed. Another potential benefit of pentobarbitone may be control of long QT syndrome. The chief benefits of some form of anesthesia (eg, profofol) are to reduce dyspnea, enable muscle rest, and help overcome primary muscle fatigue and general exhaustion. Periods of 6–8 hr of light anesthesia are best, with reassessment of clinical status after each period.

Mechanical or manual ventilation may be required but should be carefully assessed because recovery can be delayed, especially in brachycephalic animals. Longer-term ventilation cases can have a 70% recovery rate. It is essential to assess pulmonary (expired CO2 levels) and alveolar (pulse oximetry) ventilatory capacity and to be aware of profound respiratory muscle fatigue. Alveolar disease (edema and/or pneumonia) has a poor prognosis in such cases.

Atropine (repeated every 6 hr, lowest dose) can be used if GI and respiratory secretions are excessive, but its effect on tear secretion (and the host’s potential for eyelid paralysis, reduced blink reflex, and corneal drying) and cardiac rate and rhythm changes should be considered.

Antiemetic therapy should be used in animals that are vomiting, which is usually a poor prognostic sign. If the animal is regurgitating, the esophagus should be aspirated along with the upper respiratory tract. Correct drainage positioning then becomes a vital factor in helping to avoid aspiration. Care is needed with gastroesophageal reflux cases regarding their chronicity and tissue damage.

Broad-spectrum bactericidal antibiotics are indicated (especially in severe cases) to help avoid development of aspiration pneumonia, but they must be given as soon as possible. Dogs with upper respiratory tract obstruction require either tracheotomy or anesthesia and intubation to overcome the potentially lethal effects of such obstruction.

Diuretics (eg, furosemide) with maximally appropriate oxygen treatment are indicated to treat congestive heart failure. Verapamil (0.1 mg/kg, IV bolus) has been used to help relieve the basic toxic myocardial effect of a failure to relax. The toxin does unbind, so if the animal can be kept free of terminal pulmonary edema (or arrhythmia), the cardiac failure will reverse over a few days, provided routine support is given. Esmolol has been used to treat affected animals that have a long QT interval and the potential for a lethal, unpredictable ventricular arrhythmia.

Fluid therapy should be used with great care, because pulmonary edema can be induced easily. Staying below maintenance levels and ensuring the animal is assessed for edema, both before and during IV fluid therapy, should be routine. Dehydration can occur in tick paralysis but not usually in routine cases until the second day of hospitalization, when increased PCV and protein values may be evident. In small patients, SC or IP fluids can be given if lung status is a concern. Exceptional cases may require extensive rehydration (eg, paralyzed in the sun with high humidity and temperature for a day before presentation), but the extent of the underlying organ dysfunction should be assessed before intensive fluids are given.

The asthma-like disease in cats is hard to reverse, because routine bronchodilators do not seem to be effective.

Muscle fatigue can be reduced (with recovery of some muscle strength) by short periods (6–8 hr) of anesthesia. The animals remain hypercapneic but, with endotracheal intubation and O2 therapy, can establish reasonable hemoglobin saturation levels (>95%), provided there is no significant alveolar disease.

Intoxicated animals lose their ability to regulate body temperature. Animals that have fallen below 32°C (90°F) for a long period may be hard to resuscitate. Various heating mechanisms are used (hot water bottles, blankets, hot air flow blankets), but peripheral heat absorption cannot occur if arteriovenous anastomoses (shunts) are shut due to the effect of the toxin and the host’s vasoconstrictive reaction to hypothermia. Warmth applied at the lower limbs (especially the hindlimbs) will be of maximal benefit; direct application to the groin area may also potentially be useful. Some animals may need warmed fluids, IV or rectally, to reverse a very cold presentation (eg, ≤32°C). Sudden hyperthermia (>42°C) can be seen in hospitalized dogs. They usually show exaggerated head and possibly foreleg movements and signs of anxiousness. With cooling (eg, wet towels, direct fan flow, high rate of air changes), these signs abate.

Because the animal’s condition is expected to deteriorate after ticks are removed and TAS is given, hospitalization with minimally invasive monitoring and good nursing care is necessary. The animal should be kept in a quiet, dark, comfortable area of the hospital where it can be easily seen. It should be placed on the sternum to maximize lung function. Lateral recumbency, left side down with the shoulder (not the pharynx or neck) as the highest point, is the best position for drainage. If possible, slight “head down” is also advised. Animals should never be rotated unless it can be done frequently (every 1–2 hr), day and night.

Because the animal cannot void, catheterization is necessary, with the bladder expressed at least twice daily to avoid infection. As with other localized tick toxicity effects, this may persist beyond the period when the animal has generally recovered. Eye protectants should be used to prevent corneal ulceration or dryness (lid closure, artificial tears, contacts). Suction of the pharynx, larynx, and proximal esophagus minimizes upper respiratory tract distress caused by saliva pooling and regurgitation. An esophageal tube may be slowly inserted to remove any pooled material; in some cases, this is voluminous and the tube may possibly prevent choke (seen mostly in brachycephalic breeds with laryngeal blockage by foreign material). Fluid and oxygen therapy should be monitored to avoid overhydration or under-supply, respectively. Nutritional support should be performed carefully to ensure that GI and respiratory function can cope with any offered food and water.

Repeated tick searches should be performed during hospitalization, especially if the animal deteriorates unexpectedly or is slow to recover. Long or matted hair should be clipped, especially about the head and neck. Application of an acaricide may kill any ticks missed in searching. However, the stress of searching, clipping, or bathing can be detrimental in severely affected or nervous animals, in which sedation is recommended.